Transmission
Patent Information
- Application Number
- PCT/DE2026/100185
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2025-02-22
- Filing Date
- 2026-02-17
- Publication Date
- 2026-08-27
Smart Images
Figure DE2026100185_27082026_PF_FP_ABST
Abstract
Description
[0001] Attorney file: 525001 -PCT
[0002] Applicant: Framo Morat GmbH & Co KG
[0003] Franz-Morat-Straße 6
[0004] 79871 Eisenbach
[0005] Title: Gearbox
[0006] DESCRIPTION
[0007] The invention is based on a gearbox with axes arranged at angles to each other.
[0008] Examples of such gears include worm gears and bevel gears.
[0009] Worm gears consist of a helical worm and a worm wheel with spur teeth, where at least one thread of the worm engages with the spur teeth of the worm wheel. Worm gears have the disadvantage of a relatively large center distance, which essentially corresponds to the sum of the outer radius of the worm wheel and the outer radius of the worm. This center distance results in a large overall size. In principle, worm gears are geometrically and in terms of load-carrying capacity hardly limited in their gear ratio, so that theoretically ratios of up to 100 or more are possible. However, at high ratios, the efficiency drops considerably due to increasing sliding forces, so that high ratios require a relatively high input power. Bevel gears comprise a frustoconical worm and a similarly beveled gear.Although they have a smaller center distance than worm gears, they require precise positioning of the worm and gear, resulting in complex assembly of bevel gear drives. They are susceptible to positional deviations of the worm and gear, leading to reduced load-bearing capacity, increased noise, jamming, or increased backlash.
[0010] The invention is based on the objective of providing a gearbox that, compared to the prior art, has a small size while simultaneously offering high efficiency, low weight, low noise generation and low susceptibility to positional deviations, and where assembly is simplified.
[0011] This problem is solved by a transmission with the features of claim 1. The drive is characterized by being equipped with a cylindrical worm and a worm gear. The worm has at least one thread on its circumferential surface. It is driven to rotate about a geometric worm axis. The worm gear has helical teeth on its face. The worm engages with the worm gear such that its at least one thread meshes with the teeth of the worm gear, and the worm thereby drives the worm gear to rotate about a geometric worm gear axis. The worm and the worm gear are aligned with each other such that the geometric worm axis and the geometric worm gear axis are skew geometric lines whose distance d is less than an outer radius of the worm gear.The distance here is meant in a mathematical sense: the distance d is the shortest connection between these geometric lines. Each tooth of the helical gear of the worm gear has a convex tooth flank and a concave tooth flank. The worm's at least one thread has an asymmetrical profile with a first thread flank and a second thread flank, the first and second being different. The worm meshes in the worm gear such that the first thread flank engages with the convex tooth flank of one or more teeth of the worm gear, and the second thread flank engages with the concave tooth flank of one or more teeth of the worm gear.The first pressure angle, which affects the engagement of the convex tooth flank and the first thread flank, is smaller than the second pressure angle, which affects the engagement of the concave tooth flank and the second thread flank. This improves the engagement of the worm gear with the cross worm wheel and results in better force distribution during engagement. Furthermore, the load-bearing capacity and efficiency are improved.
[0012] The worm gear can be equipped with one or more left-handed or right-handed threads. The spiral tooth profile of the worm gear is adapted to the thread profile.
[0013] The worm gear can be coupled directly or indirectly to a drive, such as a motor, so that the drive's torque is transmitted to the worm gear. In the case of an indirect coupling, additional gear stages are provided between the worm gear and the drive. The drive's torque is then transmitted from the worm gear to the cross-worm wheel.
[0014] Since the worm gear does not engage the gear circumferentially, but rather on its flat side, the distance between the geometric axis of the worm gear and the geometric axis of the cross worm gear is smaller than the outer radius of the cross worm gear and therefore also smaller than in worm gears known from the prior art. This results in a smaller overall size. It also allows for space-saving integration of the gearbox at its point of use.
[0015] Due to the cylindrical worm and the cross worm gear, there is one degree of freedom in the direction of the geometric worm axis during gearbox assembly. Compared to bevel gears, the robustness against deviations in the worm's orientation relative to the cross worm gear is increased in the direction of the geometric worm axis. This simplifies gearbox assembly. Furthermore, the gearbox is less susceptible to positional deviations than a bevel gear.
[0016] The cylindrical worm and the cross-worm gear have a high contact ratio. Several turns of the worm are always engaged with the helical teeth of the cross-worm gear. This results in a high power density during torque transmission. Furthermore, the combination of a cylindrical worm and a cross-worm gear with helical teeth offers improved torque transmission and kinematically favorable sliding characteristics.
[0017] Efficiency losses due to friction and wear are minimized. Furthermore, the transmission according to the invention is quiet.
[0018] According to an advantageous embodiment of the invention, the first flight flank of the worm gear faces a geometric median plane, and the second flight flank of the worm gear faces away from this geometric median plane. The geometric median plane is defined such that it is perpendicular to the geometric axis of the worm gear, and the geometric axis of the worm gear runs in this geometric median plane.
[0019] According to a further advantageous embodiment of the invention, the thread in a worm shaft extends from a first thread end to a second thread end, forming a profiled groove with a helical path within the worm shaft. This profiled groove is defined by the tooth profile of the worm. The first and second thread ends are offset axially with respect to the geometric axis of the worm. The worm shaft can also be referred to as the worm shaft. The worm shaft comprises a threaded section in which the at least one thread runs, and at least one unthreaded section that is free of the thread. At least at the first thread end, the thread has a radial extension into this unthreaded section of the worm shaft.The runout is radial with respect to the geometric worm axis and aligned with the helix angle. Preferably, the worm also has a radial runout at the second thread end into a further unthreaded section of the worm shaft. In the unthreaded section, the diameter of the worm shaft is preferably substantially the same as the outer diameter of the threaded section of the worm shaft. A connection of the two flanks, formed by the circumferential thread and extending radially outward with respect to the geometric worm axis, defines a tip circle of the worm, while the radially inward-directed limitation of the thread defines a root circle. The diameter of the worm shaft in the unthreaded section is larger than the diameter of this root circle and smaller than, equal to, or larger than the diameter of the tip circle.Due to the engagement angle of the worm and the cross worm gear, and the helix angle, a radial force component arises alongside the axial force component when a torque is applied to the gearbox, relative to the geometric axis of the worm. The radial force component acts in the opposite direction to the cross worm gear and tends to force the worm thread out of the cross worm gear's teeth. If the thread ends abruptly at its first or second thread end and the worm shank transitions into a threadless section with a reduced diameter compared to the threaded section, a sudden change in stiffness occurs, which can lead to high stresses in the worm shank, particularly bending stress. With a radial run-out of the thread, the stiffness does not change abruptly but rather smoothly.As a result, the stresses that occur are reduced and the screw is significantly more resistant to radial forces.
[0020] According to a further advantageous embodiment of the invention, the at least one thread of the worm engages with the teeth of the cross worm gear at at least three contact points. If the worm has several threads, these threads engage with the teeth of the cross worm gear at a total of at least three contact points.
[0021] According to a further advantageous embodiment of the invention, the gearbox is equipped with a gearbox base on which the worm and the cross worm gear are rotatably mounted, at least indirectly. The gearbox base can form a housing or housing part, or be connected to a housing. The gearbox base serves as a structural element that securely and precisely positions the worm and the cross worm gear, as well as any other mechanical components. The rotatable mounting of the worm and the cross worm gear on the gearbox base ensures low-friction and efficient transmission of the rotational motion. The gearbox base can be made of various materials, selected according to the application to meet specific requirements for load-bearing capacity, stiffness, weight, and temperature and humidity resistance.Integrating the worm gear and the cross worm wheel into a common gearbox base simplifies gearbox assembly, as the gearbox can be mounted as a pre-assembled unit at the point of use. The installation of individual parts on the final product is avoided or at least reduced. The positioning of the components relative to each other is predetermined by the gearbox base. This leads to a reduction in manufacturing costs and an increase in production speed. The gearbox base can also be equipped with additional mounting points, enabling easy and secure integration of the gearbox into various applications.
[0022] According to a further advantageous embodiment of the invention, the worm gear can be connected directly or indirectly to a drive at a first end. The drive can be, for example, a motor or a manual drive. The first end of the worm gear is designed to couple to a motor shaft or a manually driven shaft, thereby transmitting the drive torque to the worm gear. One or more gear stages can be provided between the drive and the worm gear. These gear stages can be referred to as upstream gear stages. The worm gear is supported on a threadless section of the worm shaft or on a worm shaft. The worm shaft can be identical to the worm shaft. Alternatively, the worm shaft can be connected to the worm shaft. The worm gear can also be rotatably mounted in a motor or in the motor housing of a motor.
[0023] According to a further advantageous embodiment of the invention, a second end of the screw, opposite the first end, is a free end. The single-sided bearing ensures that the screw is held stably and precisely in its position, guaranteeing reliable transmission of the rotational motion to the cross worm gear. The single-sided bearing of the screw simplifies the gearbox, as fewer bearing components are required, leading to a reduction in manufacturing costs and a simplification of the assembly process. Furthermore, the single-sided bearing of the screw can reduce the space requirement, which is particularly important in applications where available space is limited. Finally, the single-sided bearing of the screw can improve ease of maintenance, as access to the screw and its bearing components is facilitated.
[0024] According to a further advantageous embodiment of the invention, a second end of the worm, opposite the first end, is rotatably mounted, for example, at the gearbox base. The worm's mounting refers to the worm shaft or the worm shank. Mounting at both ends of the worm ensures that resulting gear forces, particularly radial forces, are absorbed, reducing worm deflection under the influence of these forces and thus preventing bending fracture. Furthermore, the two-sided mounting of the worm enables more stable and uniform rotation around the geometric axis of the worm, leading to a reduction in vibration and noise during operation. This additional mounting also contributes to the longevity of the components by reducing wear on the worm and the bearings.This is particularly important in applications where the gearbox is operated frequently and under varying loads. The even distribution of forces across the bearings prevents uneven loading, which extends the service life of the bearings and the worm gear.
[0025] According to a further advantageous embodiment of the invention, the gearing of the worm gear has an elliptically rounded tooth root. This means that the base of the teeth of the worm gear has an elliptical shape, resulting in a rounding. This reduces stresses in the tooth root. This, in turn, increases the load-bearing capacity and reduces the risk of tooth breakage.
[0026] According to a further advantageous embodiment of the invention, the teeth of the cross worm gear feature a chamfered tip. This means that the edges of the teeth are chamfered in the tip region. This reduces the risk of edge bearing and thus the risk of local stress peaks, which increases the service life and reliability of the cross worm gear. By avoiding local stress peaks, the probability of a reduction in load-carrying capacity is reduced, which is particularly important in applications with high loads and torques. In addition, the chamfered tip contributes to improved running characteristics and smooth operation of the cross worm gear, leading to a reduction in vibration and noise during operation. Furthermore, the chamfered tip can facilitate the assembly and installation of the cross worm gear, as the chamfered edges are less susceptible to damage during handling.
[0027] According to a further advantageous embodiment of the invention, the toothing of the worm gear has a continuous run-out on one or both sides without tooth edges. The absence of tooth edges means that the teeth do not extend to the outer or inner circumferential side of the worm gear. With a continuous run-out on both sides, the teeth do not extend to either the outer or inner circumferential side of the worm gear. With a continuous run-out on one side, the teeth extend to the inner circumferential side but not to the outer circumferential side, or vice versa. Due to the lateral connection of the tooth, it is more stable with respect to the forces acting upon it. Local stress concentrations at the tooth edges are avoided, thus increasing the load-bearing capacity against tooth edge breakage on the gear.Furthermore, the load-bearing capacity of the worm is increased in the area of the avoided tooth face edges. The lubricating film is also improved by avoiding a lubricating wedge formed by the tooth face edge. In this case, the worm must be designed and positioned relative to the worm gear such that the engagement of the worm with at least one turn in the gear teeth is located within the area of the fully formed tooth profiles of the gear teeth. Preferably, the worm's thread(s) engage with the gear teeth at at least three contact points. Outside of the fully formed tooth profiles, a collision between the worm and the gear teeth must be avoided.
[0028] According to a further advantageous embodiment of the invention, the width of each tooth of the worm gear decreases from an inner tooth end, which faces the geometric axis of the worm gear, to an outer tooth end facing away from the inner tooth end. This tooth shape is also referred to as a comma-shaped tooth head. It improves the engagement of the worm with the worm gear and ensures better force distribution during engagement.
[0029] According to a further advantageous embodiment of the invention, the transmission has at least one further transmission stage connected to the worm gear, which is coupled to the worm gear. For example, the combination of the worm and the worm gear according to the invention forms a first transmission stage that is directly connected to a drive, wherein the worm is coupled to a drive shaft. In this case, the transmission stage connected to the worm gear forms a second transmission stage that is driven by the worm gear. The second transmission stage can also comprise a combination of a worm and a worm gear according to the invention or other types of transmission, for example, a spur gear set, a planetary gear set, or a spindle drive.The additional gear stage can, for example, change the transmission ratio, convert a rotational movement into a linear movement, or redirect the torque.
[0030] According to a further advantageous embodiment of the invention, the worm gear is at least indirectly coupled to an output shaft in such a way that it transmits a torque to this output shaft. According to a further advantageous embodiment of the invention, the worm gear has at least one bearing raceway or bearing seat.
[0031] According to a further advantageous embodiment of the invention, the worm and / or the cross worm gear are made of plastic. This material has the advantage of being lightweight. Furthermore, the components can be manufactured cost-effectively in large quantities. Plastic also exhibits high corrosion resistance, which increases the durability and reliability of the components, particularly in humid or corrosive environments. Another advantage of plastic is its noise-dampening property. By using plastic for the worm and / or the cross worm gear, the operating noise of the drive is reduced. In addition, plastic offers a good balance between strength and flexibility. Shocks and vibrations can be absorbed.
[0032] According to a further advantageous embodiment of the invention, the worm and / or the cross worm gear are made of a thermoplastic or thermoset. Besides the advantages in manufacturing, the material of the worm and the cross worm gear influences the friction properties between the worm and the cross worm gear. These, in turn, affect the efficiency and service life of the gearbox.
[0033] According to a further advantageous embodiment of the invention, the worm and / or the cross worm gear are manufactured by plastic injection molding. This represents a cost-effective manufacturing process, particularly for large production runs, with which complex geometries can be produced with high precision and repeatability.
[0034] According to a further advantageous embodiment of the invention, the worm gear is manufactured by hot stamping. In this manufacturing process, the material of the worm gear is brought into the desired shape under the influence of heat and pressure. This method enables a precise and uniform shaping of the helical teeth on the face of the gear.
[0035] In a further advantageous embodiment, the worm gear is manufactured by injection molding and comprises a metallic or ceramic insert, or a plastic insert. Metallic inserts offer high strength and wear resistance, while ceramic inserts exhibit high temperature resistance and hardness. A plastic insert can be designed with or without reinforcement, for example, fiber reinforcement. A fiber-reinforced plastic insert combines the advantages of lightweight construction and increased strength through the embedding of fibers, such as glass or carbon fibers, in the plastic matrix. These inserts improve the structural integrity of the worm gear and contribute to the reduction of deformation and material fatigue. The integration of such inserts into the worm gear leads to improved performance and durability of the gearbox, especially under demanding operating conditions.
[0036] According to a further advantageous embodiment of the invention, the worm gear comprises an outer gear part, which is equipped with the helical teeth, an inner gear part, and a gear connecting part. The gear connecting part connects the outer gear part to the inner gear part.
[0037] According to a further advantageous embodiment of the invention, the wheel connecting part is made of plastic. It is injection-molded together with the outer and inner wheel parts, which are designed as inserts. During manufacturing, the outer and inner wheel parts are placed as inserts into an injection mold. The plastic from which the connecting part is made is injected into this injection mold. According to a further advantageous embodiment of the invention, the worm gear is made of a metallic or ceramic material and is sintered, at least in the area of the teeth. Metallic materials offer high strength and durability, which is particularly important for withstanding high mechanical loads. Ceramic materials, on the other hand, are characterized by their high wear resistance and temperature resistance, which is particularly advantageous in applications where high temperatures and friction occur.Sintering in the gear teeth area further improves the material properties by creating a denser and more homogeneous structure, which increases the service life and reliability of the worm gear. Sintering also increases the surface hardness in the gear teeth area, improving wear resistance and the ability to withstand high loads. This results in a longer service life for the worm gear and reduces the need for maintenance and replacement.
[0038] According to a further advantageous embodiment of the invention, the worm gear is made of sintered metal powder, at least in the area of the toothing.
[0039] According to a further advantageous embodiment of the invention, the worm gear, made of sintered metal powder, is impregnated with a lubricant, a plastic, or a metallic impregnating agent. Impregnating the worm gear with a lubricant such as oil provides the following properties: (emergency) lubrication, as the lubricant-filled pores act as a lubricant reservoir. This also increases wear resistance and provides a degree of corrosion protection. Impregnation with plastics such as resins or wax closes the pores in the material, thus achieving a seal or a degree of corrosion protection. Furthermore, impregnation with plastics is a fundamental requirement as a pretreatment for further coating processes such as electroplating.Impregnation with metallic impregnating agents, usually with low-melting alloys, can be used to compact the worm gear or to increase the mechanical strength of the worm gear.
[0040] According to a further advantageous embodiment of the invention, the worm gear is made of metal and is manufactured by investment casting.
[0041] According to a further advantageous embodiment of the invention, the worm gear is made of a metallic material and is manufactured by means of cold extrusion.
[0042] According to a further advantageous embodiment of the invention, the worm gear is made of a metallic material and is manufactured by forging.
[0043] According to a further advantageous embodiment of the invention, the worm gear is manufactured by an additive manufacturing process. Examples include powder bed fusion (SLS, SLM) and binder jetting processes, which involve plastics and metals, as well as stereolithography (SLA, MSLA), which involves plastics, and fused deposition modeling (FDM).
[0044] According to a further advantageous embodiment of the invention, the worm gear is at least partially manufactured by machining.
[0045] Further advantages and advantageous embodiments of the invention can be found in the following description, the drawing, and the claims.
[0046] The drawing shows exemplary embodiments of the invention. It shows:
[0047] Figure 1 shows the first embodiment of a gearbox in a top view.
[0048] Figure 2 Gearbox according to Figure 1 in sectional view with section along the plane marked A - A in Figure 1,
[0049] Figure 3 is a section of Figure 2 concerning the area marked B in Figure 2.
[0050] Figure 4 Worm and section of the cross worm gear of the transmission according to Figure 1 ,
[0051] Figure 5 Gearbox according to Figure 1 with motor in perspective view,
[0052] Figure 6 Gearbox according to Figure 1 with additional gear stage in front of the worm gear,
[0053] Figure 7 Gearbox according to Figure 6 in perspective view,
[0054] Figure 8 shows a second embodiment of a worm gear.
[0055] Figure 9 Drive with a second embodiment of a gearbox in a top view,
[0056] Figure 10 Drive according to Figure 9 in sectional view with section along the plane marked D - D, Figure 11 Drive according to Figure 9 in perspective view,
[0057] Figure 12 Drive according to Figure 9 in perspective view, rotated relative to the representation in Figure 11,
[0058] Figure 13 Drive according to Figure 9 in sectional view with section along the plane marked E - E,
[0059] Figure 14 shows a third embodiment of a worm gear in a perspective view from above.
[0060] Figure 15: Planing worm gear according to Figure 14 in a top view.
[0061] Figure 16 Excerpt from the illustration according to Figure 15,
[0062] Figure 17 Section through the worm gear according to Figure 14 along the plane A - A,
[0063] Figure 18 shows a fourth embodiment of a worm gear in a perspective view from above.
[0064] Figure 19 shows the fifth embodiment of a worm gear in a perspective view from above.
[0065] Figure 20 shows the sixth embodiment of a cross-worm gear in a top view.
[0066] Figure 21 shows a cross-cutting worm gear according to Figure 20 in a sectional view with a section along the plane marked A - A in Figure 20.
[0067] Figure 22 Cross-winding worm gear according to Figure 20 in a perspective view from above, Figure 23 further drive with the second embodiment of a gearbox and a downstream further gearbox stage in a view from above
[0068] Figure 24 Drive according to Figure 23 in sectional view with section along the plane marked C - C,
[0069] Figure 25 Drive according to Figure 23 in perspective view,
[0070] Figure 26 Gearbox according to Figure 1 with left-hand rising worm gear,
[0071] Figure 27 shows a third embodiment of a gearbox with a right-hand rising worm gear.
[0072] Figure 28 Example of a screw with radial outlet of the thread.
[0073] Description of the exemplary implementations
[0074] Figures 1 to 7 show a first embodiment of a gearbox 1. The gearbox 1 comprises a cylindrical worm 2, which can be rotated about a geometric worm axis 3. For this purpose, a motor shaft of the motor 12 shown in Figure 5 (not shown in the drawing) can be connected to a worm shaft 9 of the worm 2. Alternatively, as shown in Figure 6, a further gear stage 14 can be provided upstream of the worm 2. The worm 2 has a thread 4 with a constant pitch on its circumferential surface. The gearbox 1 also includes a cross worm gear 5, which has a helical toothing 7 on one face 6. This toothing 7 is located on the outer edge of the cross worm gear 5. The worm 2 is in operative engagement with the cross worm gear 5, with the thread 4 of the worm 2 engaging in the toothing 7 of the cross worm gear 5.This causes the worm gear 5 to rotate around a geometric worm gear axis 8.
[0075] The geometric worm axis 3 and the geometric worm gear axis 8 are skew geometric lines whose distance d is smaller than the outer radius R of the worm gear 5. The distance d and the radius R are shown in Figure 1. The illustration clearly shows that the distance d is smaller than the radius R.
[0076] Figure 2 shows a section along the plane labeled AA in Figure 1. Figure 3 shows a detail from Figure 2. In these views according to Figures 2 and 3, it can be seen that the thread 4 of the worm 2 engages in the helical teeth 7 of the cross-worm gear 5, thereby rotating the cross-worm gear 5 about the cross-worm gear axis 8. The face 6 of the cross-worm gear 5 with the helical teeth 7, which meshes with the thread 4 of the worm 2, is also visible.
[0077] Figures 3 and 4 show the engagement of the worm with the crossworm gear. Each tooth of the helical gear 7 of the crossworm gear has a convex tooth flank 10 and a concave tooth flank 11. The thread of the worm 2 has an asymmetrical profile with a first thread flank 4a and a second thread flank 4b. The first thread flank 4a of the worm thread engages with the convex tooth flank 10 of the teeth of the helical gear of the crossworm gear 5. The second thread flank 4a of the worm thread 4 engages with the concave tooth flank 11 of the teeth of the helical gear of the crossworm gear 5. The first engagement angle is α. a The pressure angle of the first tooth flank 4a with the convex tooth flank 10 is smaller than the pressure angle of the second tooth flank 4b with the concave tooth flank 11. The first pressure angle a aand the second engagement angle defines the contact geometry between the worm 2 and the cross worm wheel 5.
[0078] Figures 3 and 4 further show that the toothing 7 of the cross-worm gear 5 has an elliptically rounded tooth root shape. Furthermore, it can be seen in Figure 3 that the toothing 7 of the cross-worm gear 5 has a tip chamfer, which reduces the mechanical stress on the tooth tips.
[0079] Figure 5 shows the gearbox 1 with a motor 12 and a shaft 13 on which the cross worm gear 5 is mounted. The worm shaft 9 shown in Figure 1 is non-rotatably connected to a motor shaft of the motor 12 (not shown). The second end of the worm 2, opposite the motor 12, is free. It is not additionally supported. The motor 12 drives the worm 2 to rotate. The torque of the motor is transmitted to the worm and from the worm to the cross worm gear 5. The shaft 13 serves as an output shaft, via which the torque from the cross worm gear 5 can be transmitted to a component not shown in the drawing.
[0080] Figures 6 and 7 show a threaded stage 14 upstream of the gearbox 1. This stage comprises an input gear 15, a shaft 16, which may be coupled to a motor (not shown) or to another upstream gearbox stage (not shown), and an output gear 17. The input gear 15 meshes with the output gear 17. The output gear 17 is in turn non-rotatably connected to the worm 2.
[0081] For this purpose, the output gear 17 is coupled to the worm shaft 9. The upstream gear stage 14 serves to adjust a gear ratio between a drive and the worm 2.
[0082] Figure 8 shows a second embodiment of a cross-worm gear 18. This embodiment differs from the first embodiment of a cross-worm gear 5 according to Figures 1 to 5 in that, in the second embodiment, the teeth 19 have a shape that is referred to as a comma head. The width of each tooth 19 is greater at its inner end 19a, which faces the geometric axis 8 of the cross-worm gear, than at its outer end 19b, which faces away from the inner end 19a and the geometric axis 8 of the cross-worm gear. The width of each tooth 19 thus decreases from the inside out.
[0083] Figures 9 to 13 show a further drive 20 with a second embodiment of a gearbox. The cross-worm gear 5 with geometric cross-worm gear axis 8 corresponds to the first embodiment of the gearbox 1 in Figures 1 to 5. The motor 12 is identical to the motor shown in Figure 5. Therefore, the same reference numerals are given for these corresponding components in Figures 9 to 13. However, the worm 22 differs from the worm 2 of the gearbox 1 according to the first embodiment. Unlike the worm 2, the worm 22 is rotatably mounted at its end facing away from the motor 12 in a bearing 28. This bearing 28 is arranged in a bearing receptacle 27, which is part of a gearbox base 24. The bearing 28 is shown in Figure 13. The motor housing 12 and the cross-worm gear 5 are mounted on the gearbox base 24.The worm 22 is driven by the motor 12 to rotate around the geometric worm axis 23. Figure 12 shows that the gearbox base 24 is closed by a cover 25. Figure 12 also shows an output shaft 26 protruding from the gearbox base 24. It is connected to the cross-worm gear 5. A component, not shown in the drawing, can be coupled to the output shaft and moved by the drive 20.
[0084] Figures 10 to 18 show various embodiments of a cross-worm gear. The third embodiment of a cross-worm gear 35, shown in Figures 14 to 17, has a helical toothing 37 on its face 36 with continuous runout on both sides and no tooth edges. The cross-worm gear 35 has the outer shape of a cylindrical disk with a central through-hole 41. The central through-hole 41 serves to accommodate a shaft (not shown in Figures 14 to 17) or other connecting element that supports the rotary motion of the cross-worm gear 35 and may optionally serve as an output shaft. The helical toothing 37 is located on the face 36, which, with respect to the geometric shape of the cross-worm gear, forms a lid of the cylinder. The toothing 37 is formed by recesses on the face 36. These recesses extend radially in a helical pattern.However, they do not extend to the central through-opening, nor to an outer circumferential side of the worm gear 35. Therefore, there are no tooth edges at either the through-opening or the circumferential side. Instead, each of the recesses is equipped with an inner outlet 38 near the central through-opening 41 and an outer outlet 39 near the circumferential side of the worm gear 35. The depth of the recesses decreases continuously at the inner outlet 38 and the outer outlet 39. This is particularly evident in the sectional view according to Figure 17.
[0085] Figure 16 shows the engagement area 40 of a worm gear (not shown). The illustration shows that the engagement area is located within the fully formed tooth profile between the inner outlet 38 and the outer outlet 39.
[0086] Figure 18 shows a fourth embodiment of a cross-worm gear 45. This differs from the cross-worm gear 35 shown in Figure 14 in that the cross-worm gear 45 has a toothing with an outer outlet 49, while the recesses extend to the central through-opening, so that tooth face edges are formed there.
[0087] Figure 19 shows a fifth embodiment of a cross-worm gear 55. This differs from the cross-worm gear 35 shown in Figure 10 in that the cross-worm gear 55 has a toothing with an inner outlet 58, while the recesses extend outwards to the circumferential side, so that tooth face edges are formed there.
[0088] Figures 20 to 22 show a sixth embodiment of a cross worm gear 65. Like the preceding embodiments, the cross worm gear 65 has a through-opening 71 centrally located with respect to the geometric axis 68 of the cross worm gear. The cross worm gear 65 comprises an insert 69, which is placed into an injection mold (not shown in the drawing) during manufacturing by plastic injection molding. The insert 69 consists of a first material, for example, metal or ceramic. In the region 70 of the helical teeth 67 on the face 66, the insert 69 is overmolded with a plastic. The cross worm gear 65 can also be manufactured by multi-component injection molding. In this case, the insert 69 consists of a first component and the region 70 of a second component.
[0089] Figures 23 to 25 show another drive 100, which is equipped with a gearbox according to Figures 9 to 13. The drive comprises a gearbox base 114 on which a motor 12, a cylindrical worm 22, and a cross-worm gear 105 are mounted. The motor 12, the worm 22, and the bearing 27 correspond essentially to the drive 20 and gearbox shown in Figures 9 to 13, and are therefore designated with the same reference numerals. The worm is driven by the motor 12 to rotate about a geometric worm axis 23. At the end facing away from the motor 12, the worm 22 is rotatably mounted on the bearing 27. The bearing receptacle 27 is arranged on the gearbox base 114.The cross-worm gear 105 is provided with a spiral toothing on one face and is in effective engagement with the worm 22, so that the worm 22 meshes with its thread in the toothing of the cross-worm gear 105 and drives it to rotation about a geometric cross-worm gear axis 108.
[0090] In contrast to the drive and transmission in Figures 9 to 13, the transmission in Figures 23 to 25 is equipped with a second transmission stage in addition to the first transmission stage, which comprises the worm 22 and the cross worm gear 105. This second transmission stage has a first gear 109 with spur teeth and a second gear 110 with spur teeth. The first gear 109 with spur teeth is either rotationally fixed to the cross worm gear 105 or is formed from a single piece with the cross worm gear 105. This is particularly evident in Figure 24. The torque of the cross worm gear 105 is thus transmitted to the first gear 109, which rotates together with the cross worm gear 105 about the geometric axis 108 of the cross worm gear. The second gear 110 meshes with its face teeth in the face teeth of the first gear 109.The torque is transmitted to the second gear 110, which is driven to rotate about a geometric gear axis 111. The geometric axis 108 of the cross worm gear 105 and the first gear 109, and the geometric gear axis, are parallel to each other. They are spaced apart, a distance which is denoted by M in Figures 23 and 24. The second gear 110 is connected to an output shaft 116, which projects from the gearbox base 114. The gearbox base 114 is fitted with a cover 115. The gearbox base and the cover form a closed housing, which protects the gearbox from external influences. Figures 26 and 27 show a left-hand worm 2 and a right-hand worm 202, each with its associated cross worm gear 5, 205, for comparison. The worms 2, 202 are each rotatably mounted at only one end.Figures 26 and 27 further show the orientation of the first thread flank 4a, 204a and the second thread flank 4b, 204b of the worm thread 2, 202 relative to a geometric median plane 200, 210. This geometric median plane 200, 210 is perpendicular to the geometric worm axis 3, 203. The geometric axis of the cross worm gear 8, 208 runs in this geometric median plane 200, 210. The left-hand worm 2 according to Figure 26 is arranged relative to the cross worm gear 5 such that the first tooth flank 4a, which engages with the convex tooth flank of the cross worm gear 5, faces the geometric median plane 200.The same applies to the right-handed worm 202 according to Figure 27: The right-handed worm 202 is arranged relative to the cross-worm gear 205 such that the first tooth flank 204a, which engages with the concave tooth flank of the gear teeth of the cross-worm gear 205, faces the geometric median plane 210. The helical teeth of the cross-worm gear 5, 205 are adapted to the worm 2, 202.
[0091] Figure 28 shows a worm gear with a worm shaft 217 and a thread 214. The thread 214 forms a profiled groove in the worm shaft 217. It runs helically or in the manner of a helix along the circumferential side of the cylindrical worm shaft 217 and extends from a first thread end 215 to a second thread end 216. The worm shaft 217 has a threaded section in which the thread 214 is located. In addition, the worm shaft has an unthreaded section. At the first thread end 215, the thread 214 extends radially into the unthreaded section of the worm shaft. The diameter of the unthreaded section corresponds to the outer diameter of the threaded section of the worm shaft 217. A burr 218 formed by the thread 214 projects radially outwards with respect to the geometric axis of the worm and forms a tip circle.The root 219 of the thread 214 forms a root circle. The diameter of the tip circle corresponds to the diameter of the unthreaded section of the worm shaft.
[0092] All features of the invention can be essential to the invention, both individually and in any combination. Reference numerals
[0093] 1 gearbox
[0094] 2 snails
[0095] 3 Geometric worm axis
[0096] 4 threads
[0097] 4a first thread flank
[0098] 4b second thread flank
[0099] 5 paddling worm gear
[0100] 6 Plan page
[0101] 7 Spiral toothing
[0102] 8 Geometric worm gear axle
[0103] 9 worm shaft
[0104] 10 Convex flank of the face gear teeth
[0105] 11 Concave flank of the face gear teeth
[0106] 12 engine
[0107] 13th wave
[0108] 14 Upstream gear stage
[0109] 15 Drive-side gear of the upstream gear stage 16 Shaft
[0110] 17 Output-side gear of the upstream gear stage 18 Crossworm gear
[0111] 19 teeth
[0112] 19a inner tooth end
[0113] 19b outer end of tooth
[0114] 20 Drive
[0115] 22 snail
[0116] 23 Geometric worm axis
[0117] 24 gearbox base
[0118] 25 lids
[0119] 26 Output shaft
[0120] 27 Bearing mount 28 Bearing for screw
[0121] 35 Splash worm gear
[0122] 36 Plan page
[0123] 37 Spiral toothing
[0124] 38 outlet inside
[0125] 39 outlet outside
[0126] 40 Intervention area of the snail
[0127] 41 Passage opening
[0128] 45 Splash worm wheel
[0129] 49 outlet outside
[0130] 55 Splash worm gear
[0131] 58 outlet inside
[0132] 65 Splash worm wheel
[0133] 66 Plan page
[0134] 67 spiral teeth
[0135] 68 geometric worm gear axle
[0136] 69 inserts made from a first material
[0137] 70 Overmolded area made of a second material 71 Through-hole
[0138] 100 drive
[0139] 105 Splash worm gear
[0140] 108 geometric worm gear axle
[0141] 109 Gear with face teeth
[0142] 110 Gear with face teeth
[0143] 111 geometric gear axis
[0144] 114 Gearbox base
[0145] 115 lids
[0146] 116 Output shaft
[0147] 200 geometric midplane
[0148] 202 Snail
[0149] 203 geometric worm axis
[0150] 204a first thread flank 204b second thread flank
[0151] 205 Splash worm wheel
[0152] 208 geometric worm gear axis 210 geometric midplane
[0153] 214 threads
[0154] 215 first end of aisle
[0155] 216 second course end
[0156] 217 snail shaft
[0157] 218 Head Circle
[0158] 219 foot circle
Claims
Attorney file: 525001 -PCT Applicant: Framo Morat GmbH & Co KG Franz-Morat-Straße 6 79871 Eisenbach Title: Gearbox REQUIREMENTS 1. Gearbox with a cylindrical worm (2, 22, 202) which is driven to rotation about a geometric worm axis (3, 23, 203) and which has at least one thread (4) on its circumferential surface, with a cross-cutting worm gear (5, 35, 45, 55, 65, 105, 205) which has a helical toothing (7, 37) on one face (6, 36), wherein the worm (2, 22, 202) is in effective engagement with the cross-cutting worm gear (5, 35, 45, 55, 65, 105, 205) such that the worm (2, 22, 202) meshes with its at least one thread in the toothing of the cross-cutting worm gear (5, 35, 45, 55, 65, 105, 205) and the worm (2, 22, 202) thereby rotates the cross-cutting worm gear (5, 35, 45, 55, 65, 105, 205) by a geometric drives the worm gear axle (8, 68, 108, 208) to rotation, wherein the geometric worm axis (3, 23, 203) and the geometric worm gear axis (8, 68, 108, 208) are skew geometric straight lines whose distance d is less than an outer radius R of the worm gear (5, 35, 45, 55, 65, 105, 205) wherein each tooth of the helical toothing (7) of the worm gear (5, 35, 45, 55, 65, 105, 205) has a convex tooth flank (10) and a concave tooth flank (11), wherein the thread (4) of the worm (2, 22, 202) has an asymmetrical profile with a first thread flank (4a, 204a) that engages with the convex tooth flank (10) of the cross worm gear (5, 35, 45, 44, 65, 105, 205) and with a second thread flank (4b, 204b) that engages with the concave tooth flank (11) of the cross worm gear (5, 35, 45, 55, 65, 105, 205), wherein a first pressure angle a athe convex tooth flank (10) and the first thread flank (4a, 204a) is smaller than a second pressure angle from the concave tooth flank (11) and the second thread flank (4b, 204b).
2. Gearbox according to claim 1, characterized in that the first gear flank (4a, 204a) of the worm (2, 22, 202) faces a geometric median plane (200, 210) and the second gear flank (4b, 204b) of the worm (2, 22, 202) faces away from this geometric median plane (200, 210), wherein the geometric median plane (200, 210) is perpendicular to the geometric worm axis (3, 23, 203) and the geometric cross worm gear axis (8, 68, 108, 208) runs in this geometric median plane (200, 210).
3. Gearbox according to claim 1 or 2, characterized in that the worm (2, 22, 202) is equipped with at least one left-hand or right-hand thread.
4. Gearbox according to one of the preceding claims, characterized in that the thread (4) in a worm shaft (217) of the worm (2, 22, 202) forms a profiled indentation with a helical profile and extends from a first thread end (215) to a second thread end (216) with respect to the geometric worm axis (3, 23, 203), and that the thread (4) has at least at the first thread end (215) a radial run-out with respect to the geometric worm axis (3, 23, 203) into a thread-free section of the worm shaft (217).
5. Gearbox according to one of the preceding claims, characterized in that the at least one thread (4) of the worm (2, 22, 202) is in effective engagement with the toothing (7, 37) of the cross worm gear (5, 35, 45, 55, 65, 105, 205) at at least three contact points.
6. Gearbox according to one of the preceding claims, characterized in that it is equipped with a gearbox base (24, 114) on which the worm (2, 22, 202) and the cross worm wheel (5, 35, 45, 55, 65, 105, 205) are at least indirectly rotatably mounted.
7. Gearbox according to one of the preceding claims, characterized in that the worm (2, 22) can be connected indirectly or directly to a drive at a first end.
8. Gearbox according to claim 7, characterized in that a second end of the worm (2, 202) opposite the first end is a free end.
9. Gearbox according to claim 7, characterized in that a second end of the worm (22) opposite the first end is rotatably mounted.
10. Gearbox according to one of the preceding claims, characterized in that the toothing (7, 37, 67) of the cross worm gear (5, 35, 45, 55, 65, 105, 205) has an elliptically rounded tooth root.
11. Gearbox according to one of the preceding claims, characterized in that the toothing (7, 37, 67) of the cross worm gear (5, 35, 105, 205) has a chamfered end.
12. Gearbox according to one of the preceding claims, characterized in that the toothing (37) of the cross worm gear (35, 45, 55) has a continuous run-out on one or both sides without tooth end edges.
13. Gearbox according to one of the preceding claims, characterized in that, in each tooth (19) of the worm gear (18), its width at the tooth head decreases from an inner tooth end (19a) which faces the geometric worm gear axis (8) to an outer tooth end (19b) facing away from the inner tooth end (19a).
14. Gearbox according to one of the preceding claims, characterized in that it has at least one further gear stage adjoining the worm gear, which is coupled to the worm gear (5, 35, 105, 205) on the output side.
15. Gearbox according to one of the preceding claims, characterized in that the worm gear (5, 105) is coupled at least indirectly to an output shaft (26, 116) in such a way that it transmits a torque to this output shaft (26, 116).
16. Gearbox according to one of the preceding claims, characterized in that the worm gear has at least one bearing running surface or bearing seat.
17. Gearbox according to one of the preceding claims, characterized in that the worm (2, 22, 202) and / or the cross worm wheel (5, 35, 45, 55, 65, 105, 205) are made of plastic.
18. Gearbox according to claim 17, characterized in that the worm (2, 22, 202) and / or the cross worm gear (5, 35, 45, 55, 65, 105, 205) are made of a thermoplastic or thermoset.
19. Gearbox according to claim 17 or 18, characterized in that the worm (2, 22, 202) and / or the cross worm gear (5, 35, 45, 55, 65, 105, 205) are manufactured by plastic injection molding.
20. Gearbox according to claim 17 or 18, characterized in that the cross worm gear (5, 35, 45, 55, 65, 105, 205) is manufactured by hot stamping.
21. Gearbox according to one of the preceding claims, characterized in that the worm gear (65) is manufactured by injection molding and comprises a metallic or ceramic insert (69) or a plastic insert.
22. Gearbox according to one of the preceding claims, characterized in that the cross worm gear has an outer gear part which is equipped with the spiral toothing, an inner gear part and a gear connecting part, wherein the gear connecting part connects the outer gear part to the inner gear part.
23. Gearbox according to claim 22, characterized in that the wheel connecting part is made of plastic and is cast together with the outer and inner wheel parts designed as inserts by injection molding.
24. Gearbox according to one of claims 1 to 16, characterized in that the cross worm gear (5, 35, 45, 55, 65, 105, 205) is made of a metallic or ceramic material.
25. Gearbox according to one of the preceding claims, characterized in that the worm gear is made of sintered metal powder, at least in the area of the teeth.
26. Gearbox according to claim 25, characterized in that the worm gear is impregnated with a lubricant, a plastic, or a metallic impregnating agent.
27. Gearbox according to one of claims 1 to 16, characterized in that the cross worm gear (5, 35, 45, 55, 65, 105, 205) is made of a metallic material and is manufactured by investment casting.
28. Gearbox according to one of claims 1 to 16, characterized in that the cross worm gear (5, 35, 45, 55, 65, 105, 205) is made of a metallic material and is manufactured by means of cold extrusion.
29. Gearbox according to one of claims 1 to 16, characterized in that the cross worm gear (5, 35, 45, 55, 65, 105, 205) is made of a metallic material and is produced by forging.
30. Gearbox according to one of the preceding claims, characterized in that the cross worm gear (5, 35, 45, 55, 65, 105, 205) is manufactured by an additive manufacturing process.
31. Gearbox according to one of the preceding claims, characterized in that the cross worm gear (5, 35, 45, 55, 65, 105, 205) is at least partially manufactured by machining.
32. Gearbox according to one of the preceding claims, characterized in that it is equipped with grease or oil lubrication.