Hard gear harmonic reducer

Abstract

According to the hard gear harmonic reducer, the two layers of rolling bodies are clamped between the tooth grooves of the inner hard gear and the tooth grooves of the outer hard gear, the two layers of rolling bodies are used for replacing radial movement of a flexible gear, transmission is achieved, torque is higher, the service life is longer, and contact parts of all parts in a torque transmission route are in rolling contact all the time.

Description

Hardened gear harmonic reducer Technical Field

[0001] This utility model relates to a transmission device for a gearbox and belongs to the field of mechanical technology. Background Technology

[0002] Currently known harmonic reducers use flexible gears that require continuous radial deformation. This design makes the material highly susceptible to fatigue, resulting in lower torque capacity and shorter lifespan. US Patent [US9297442B1] discloses a device that uses a ring chain structure instead of gears in the reducer as the transmission mechanism. However, in this device, torque transmission is achieved through pins 112 or 218 in the chain. Furthermore, the component in contact with the pin is either a pin disc 118 or a roller 219. Due to the rotation of the roller or the pin, sliding friction inevitably exists at the contact point and cannot be eliminated. Furthermore, Chinese patent [CN2022109777833] discloses a swing shaft transmission mechanism in which two layers of annular chains serve as the transmission medium between two gears. In this mechanism, the rolling speeds of the outer and inner rolling elements are different. For example, when the outer rolling element rolls a distance of one tooth on the gear tooth surface, the inner rolling element needs to roll a distance of two teeth on the gear tooth surface. Therefore, an oil wedge is needed between the two rolling elements to eliminate sliding friction. When the oil wedge fails, sliding friction is unavoidable.

[0003] In order to solve the above problems, this utility model is proposed. Summary of the Invention

[0004] A hardened gear harmonic reducer is characterized by comprising at least two gears, A1 and B1, with different numbers of teeth. The two gears have the same axial position. A ring consisting of two layers of rolling elements is installed between the two gears. The first layer of rolling elements meshes with gear A1, and the second layer meshes with gear B1. Thrust can be transmitted between the two layers of rolling elements. A wave generator, driven by an input shaft, pushes the two layers of rolling elements to engage and disengage between gears A1 and B1. Due to the different number of teeth on the two gears, speed reduction is achieved. Compared to known harmonic reducers, this invention uses a combination of two layers of rolling elements and hardened gears to replace the radial deformation of the flexible gear, thus solving the problems of material fatigue and low torque. Furthermore, the friction between the ring consisting of the two layers of rolling elements and gears A1 and B1 during radial movement is rolling friction.

[0005] A further advantage is that, since there is no swing shaft structure, the shafts of gear A1 and gear B1 are the same and fixed, and the rolling of the two layers of rolling elements can be synchronized. Even if the oil wedge between the two layers of rolling elements fails, there will still be no sliding friction. Thus, the main contact parts in the reducer can achieve rolling contact.

[0006] The purpose of this invention is to provide a harmonic reducer with higher torque and longer service life, wherein the contact parts of each component in the torque transmission path are all in rolling contact.

[0007] Furthermore, to maintain rolling contact between the rolling elements and the gear contact surface, the following data was obtained through modeling and experimental testing: the number of teeth on gear A1 is the same as the number of rolling elements in contact with it, and the tooth profile curve of gear A1 is a circular arc curve with a radius of R1. The radius of the rolling element in contact with it is R2, therefore R1 ≥ 1.06 × R2. The purpose is to prevent the rolling elements and gear tooth surfaces from sticking or seizing under heavy loads, thus maintaining rolling contact. The value of 1.06 was obtained experimentally based on commonly used materials and extreme operating conditions. Under extreme conditions, the lubricant will coke and combine with tiny debris generated during operation to form hard lumps, which will accelerate the wear of the reducer and even cause it to seize. However, when the value is greater than 1.06, the situation is significantly improved.

[0008] In this invention, the number of teeth on gears A1 and B1 and the number of rolling elements in each layer can be combined in various ways. These combinations include, but are not limited to, one of the following: when the number of teeth on the inner gear on the outer ring is N, the number of teeth on the central gear is N-2, and the number of rolling elements in each layer is N; or, when the number of teeth on the inner gear on the outer ring is N+2, the number of teeth on the central gear is N, and the number of rolling elements in each layer is N. In both of these combinations, the number of teeth on gears A1 and B1 is not a prime number. The purpose of not having a prime number of teeth is to allow the gears to be processed quickly using a multi-head grinding machine, reducing production costs.

[0009] Furthermore, the design schemes for the tooth profile curves of gears A1 and B1 include, but are not limited to, the following schemes: at least one gear has a tooth profile curve containing a circular arc curve, or at least one gear has a tooth profile curve containing a cycloid, or at least one gear has a tooth profile curve containing an elliptical curve, including one or more of the above schemes.

[0010] According to the reducer disclosed in this utility model, a speed reduction device can be designed, characterized in that: it includes at least three gears, gear A1, gear B1 and gear B2, the three gears have the same shaft center position, wherein gear B1 and gear B2 have the same number of teeth and are located at the two ends of the shaft respectively, a wave generator is located in the middle position between gear B1 and gear B2, the wave generator drives two layers of rolling elements to mesh with the three gears simultaneously, wherein gear B1 and gear B2 are fixed and do not rotate, and gear A1 drives the output shaft to rotate.

[0011] According to the reducer disclosed in this utility model, a speed reduction device can also be designed, characterized in that: two wave generators are located at both ends of the shaft and rotate synchronously, and gears A1 and B1 are located between the two wave generators with their tooth surfaces facing each other. The wave generators drive two layers of rolling elements to mesh with the two gears, one of which is fixed and does not rotate, while the other gear drives the output shaft to rotate.

[0012] The reducer disclosed in this utility model has a further improvement: in the ring composed of two layers of rolling elements, at least one layer of rolling elements is composed of a chain, or both layers of rolling elements are composed of two annular chains, and the rolling elements of different layers are in direct contact. This improvement differs from known chain drives or sprocket drives. In this utility model, two adjacent rolling elements are simultaneously engaged in the tooth grooves of two gears, and the torque is mainly transmitted directly by the two adjacent rolling elements. The connecting piece of the chain is mainly responsible for positioning the rolling elements, and the force it experiences is very small. Therefore, during long-term use, the connecting piece of the chain is not easily stretched, and its service life is longer.

[0013] To prevent the ring chain from moving axially, the present invention provides the following solution: the ring chain includes connecting pieces that connect the various chain links. The edges of the connecting pieces protrude, and the protruding parts are located at both ends of the edge of the gear tooth profile in the axial section of the gear. Their purpose is to act as guards to restrict the ring chain from falling off axially.

[0014] The wave generator described in this invention contacts the ring formed by the two rolling elements through a third rolling element and a flexible annular material. This structure ensures that the wave generator makes rolling contact with the two rolling elements when it rotates.

[0015] This utility model of hard gear harmonic reducer can be used with various engines to form a power output module. The engine may include, but is not limited to, an axial flux motor, an external rotor motor, an internal rotor motor, or a turbine.

[0016] This utility model of hard gear harmonic reducer can be applied to various mechanical transmission systems. Its application scenarios include, but are not limited to, propeller drives, hub drives, or mechanical joints. Among them, mechanical joints include, but are not limited to, rotary joints of industrial machinery, wearable robotic arms, human-machine collaborative mechanical devices, robotic hands, vehicle steering systems, aircraft steering rudder transmission systems, or ship steering rudder transmission systems.

[0017] The technical advantages and scope of protection of this utility model will become clearer with reference to the accompanying drawings. The drawings and their descriptions are for illustrative purposes only and the specific examples therein do not limit the scope of protection of this utility model. Attached Figure Description

[0018] Symbol explanations in the diagram: A1 – Outer ring internal gear No. 1; B1 – Center gear No. 1; B2 – Center gear No. 2; C – Section position; D1 – First rolling element in two layers of rolling elements; D2 – Second rolling element in two layers of rolling elements; D3 – Third rolling element; E – Wave generator; E1 – Flexible ring structure; F1 – First bearing; F2 – Second bearing; F3 – Third bearing; F4 – Fourth bearing; F5 – Fixed shaft; H1 – Rotor of the electric motor; H2 – Stator of the electric motor; O – Shaft center position; J – Chain connecting piece.

[0019] Figure 1 shows a hard gear harmonic reducer based on the structural design disclosed in this utility model, and this reducer and an external rotor motor are combined into a power output module. The figure shows the axial cross-sectional view of the module.

[0020] Figure 2 is a radial cross-sectional view of section C1 in Figure 1.

[0021] Figure 3 is a radial cross-sectional view of section C2 in Figure 1.

[0022] Figure 4 shows two axial views of the two-layer rolling element structure in this utility model. Detailed Implementation

[0023] The advantages and preferred embodiments of this utility model are described with reference to the accompanying drawings. Specific examples are provided to illustrate the advantages of this utility model and should not be construed as limiting the scope of protection of this utility model.

[0024] Figure 1 shows a hard-gear harmonic reducer designed according to the structure disclosed in this utility model. This reducer is combined with an external rotor motor to form a power output module. The figure shows the axial cross-sectional view of this module. The fixed shaft F5 is located in the middle of the figure. The fixed shaft F5 is also the fixed shaft of the external rotor motor. The stator H2 of the motor, the center gear B1, and the center gear B2 are fixedly connected to the fixed shaft F5. The rotor H1 of the motor is mounted on the fixed shaft F5 through bearings F3 and F4. The wave generator E is fixedly mounted on the motor rotor H1. The outer side of the wave generator E is the third layer of rolling elements D3. The outer side of the third layer of rolling elements D3 is a flexible annular structure E1. The flexible annular structure E1 is in direct contact with the second layer of rolling elements D2. The second layer of rolling elements meshes with the center gears B1 and B2, and simultaneously contacts the first layer of rolling elements D1. The first layer of rolling elements D1 meshes with the outer ring gear A1.

[0025] Figure 2 is a radial cross-sectional view of section C1 in Figure 1. The center of Figure 2 is shaft O, which is the shaft of the electric motor and also the shaft of all gears in the hard-gear harmonic reducer. The outer periphery of shaft O is fixed shaft F5. The outer layer of fixed shaft F5 is the motor stator H2. The outer layer of motor stator H2 is the motor rotor H1. The outer layer of motor rotor H1 is fixed wave generator E. The outer layer of the wave generator is a third layer of rolling elements D3. The third layer of rolling elements D3 contacts the second layer of rolling elements D2 through a flexible annular structure E1. The second layer of rolling elements D2 and the first layer of rolling elements D1 together form a ring composed of two layers of rolling elements, as referred to in this invention. The first layer of rolling elements D1 meshes with gear A1 on the outer ring.

[0026] Figure 3 is a radial cross-sectional view of section C2 in Figure 1. The center of Figure 3 is shaft O, which is the shaft of the electric motor and also the shaft of all gears in the hard-gear harmonic reducer. The outer periphery of shaft O is fixed shaft F5. The outer layer of fixed shaft F5 is the motor stator H2, the outer layer of motor stator H2 is the motor rotor H1, and the outer layer of motor rotor H1 is the central gear B1. Referring to Figure 1, it can be seen that there is no contact between central gear B1 and motor rotor H1, and central gear B1 is fixed to fixed shaft F5. Contacting central gear B1 is the second rolling element D2. The second rolling element D2 and the first rolling element D1 together form a ring composed of two rolling elements, as referred to in this invention. The first rolling element D1 meshes with the outer ring gear A1.

[0027] The operation mode and advantages of this utility model will be explained below with reference to Figures 1, 2, and 3. As shown in Figure 2, the radial cross-section of the wave generator E is elliptical or oblong. When the wave generator E rotates with the fixed motor rotor H1, it will drive the two layers of rolling elements to make radial motion. As shown in Figure 3, the ring formed by the two layers of rolling elements meshes with gears A1 and B1 at the same time. Since the two gears have different numbers of teeth, a speed reduction transmission is generated.

[0028] In Figure 1, center gear B2 (center 2) and center gear B1 (center 1) are installed on both sides of wave generator E. The two center gears have the same number of teeth and the teeth are in the same position. This design can effectively balance the circumferential overturning force generated by the rolling element during meshing with the gear.

[0029] As shown in Figures 2 and 3, when the motor rotor H1 in Figure 2 rotates clockwise, the rolling elements D2 and D1, marked in Figure 3, move radially. These two rolling elements are directly engaged between the tooth grooves of gears B1 and A1. When the two layers of rolling elements move radially outward, torque is transmitted between the two gears through the rolling elements. Unlike chain drives or sprocket drives in known technologies, the connecting plate requires almost no force during torque transmission.

[0030] Figure 4 shows two axial views of the two-layer rolling element structure of this utility model. The upper part of Figure 4 shows that only the first rolling element D1 is composed of a chain, and the second rolling element D2 is installed between the chain links and below the connecting piece J. The second rolling element D2 does not have a connecting piece. The lower part of Figure 4 shows the case where the two rolling elements are composed of two chains.

[0031] Other specific cases can be designed based on the reducer structure proposed in this utility model. Application scenarios include, but are not limited to, combining it with a turbine shaft engine to form a power module, or combining it with an electric motor to form a power module. The electric motor can be an axial flux motor, an external rotor motor, or an internal rotor motor.

[0032] This utility model is applied in mechanical transmission devices, and its application scenarios include, but are not limited to, propeller drives, hub drives, or mechanical joints. Among them, mechanical joints include, but are not limited to, rotary joints of industrial machinery, wearable robotic arms, human-machine collaborative mechanical devices, robotic hands, vehicle steering systems, aircraft steering rudder transmission systems, ship steering rudder transmission systems, or many other application scenarios, or other mechanical actuators, which will not be listed further.

Claims

1. A hardened gear harmonic reducer, characterized by: It includes at least two gears, A1 and B1, with different numbers of teeth. The two gears have the same axial position. A ring consisting of two layers of rolling elements is installed between the two gears. The first layer of rolling elements meshes with gear A1, and the second layer meshes with gear B1. Thrust can be transmitted between the two layers of rolling elements. In addition, there is a wave generator, which can drive the two layers of rolling elements to mesh or disengage between gear A1 and gear B1 under the drive of the input shaft. Since the two gears have different numbers of teeth, speed reduction transmission is achieved.

2. The reducer according to claim 1, characterized in that: The number of teeth of gear A1 is the same as the number of rolling elements in contact with it, and the tooth profile curve of gear A1 is a circular arc curve with radius R1 and radius R2 of the rolling element in contact with it, and R1≥1.06×R2.

3. The reducer according to claim 1, characterized in that: There are multiple combinations of the number of teeth on gear A1 and gear B1 and the number of rolling elements in each layer. These combinations include one of the following: when the number of teeth on the inner gear on the outer ring is N, the number of teeth on the central gear is N-2, and the number of rolling elements in each layer of the two rolling elements is N; or, when the number of teeth on the inner gear on the outer ring is N+2, the number of teeth on the central gear is N, and the number of rolling elements in each layer of the two rolling elements is N. In both of these combinations, the number of teeth on gear A1 and gear B1 is not a prime number.

4. The reducer according to claim 1, characterized in that: the gears... The design schemes for the tooth profile curves of A1 and gear B1 include the following schemes: at least one gear tooth profile curve contains a circular arc curve, or at least one gear tooth profile curve contains a cycloid, or at least one gear tooth profile curve contains an elliptical curve, including one or more of the above schemes.

5. The reducer according to claim 1, characterized in that: The wave generator and gears can be designed in one of two ways. The first way is to include at least three gears, gear A1, gear B1, and gear B2, with the three gears having the same axial center position. Gears B1 and B2 have the same number of teeth and are located at opposite ends of the shaft. The wave generator is located in the middle between gears B1 and B2. The wave generator drives two layers of rolling elements to mesh with the three gears simultaneously. Gears B1 and B2 are fixed and do not rotate, while gear A1 drives the output shaft to rotate. The second way is to have two wave generators located at opposite ends of the shaft and rotating synchronously, with gears A1 and B1 located between the two wave generators.

6. The reducer according to claim 1, characterized in that: The ring consisting of two layers of rolling elements, at least one of the rolling elements is composed of a chain, or the two rolling elements are composed of two ring-shaped chains, and the rolling elements of different layers are in direct contact.

7. The reducer according to claim 1, characterized in that: The two rolling elements include an annular chain with connecting pieces that connect the links. The edges of the connecting pieces protrude and extend beyond the edge of the gear tooth profile in the gear axial direction. This protrusion serves as a stop to prevent the annular chain from detaching in the axial direction.

8. The reducer according to claim 1, characterized in that: The wave generator contacts the ring formed by the two rolling elements through a third rolling element and a flexible annular material. This structure ensures that the wave generator makes rolling contact with the two rolling elements when it rotates.

9. The hardened gear harmonic reducer according to claim 1, characterized in that: The hardened gear harmonic reducer works in conjunction with the engine to form a power output module. The engine can be any one of an axial flux motor, an external rotor motor, an internal rotor motor, or a turbine.

10. The reducer according to any one of claims 1, 2, 3, 4, 5, 6, 7, 8, or 9, characterized in that: The reducer is used in transmission systems, and its application scenarios include, but are not limited to, propeller drives, hub drives, or mechanical joints. The mechanical joints include, but are not limited to, rotary joints of industrial machinery, wearable robotic arms, human-machine collaborative mechanical devices, robotic hands, vehicle steering systems, aircraft steering rudder transmission systems, or ship steering rudder transmission systems.

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