Friction transmission speed reducer

Abstract

The friction transmission speed reducer comprises a shell, a containing space formed in the shell and extending in the first direction, a first bearing and a second bearing, the first bearing and the second bearing are sequentially and coaxially arranged in the first direction, each of the first bearing and the second bearing comprises an outer ring, an inner ring, a rolling body and a retainer, the outer ring of the first bearing is fixedly connected with the shell, and the inner ring of the second bearing is fixedly connected with the shell. The inner ring of the second bearing rotates in a controlled mode so as to accurately control the transmission speed of the input end, the inner ring of the second bearing and the inner ring of the first bearing rotate synchronously and share an integrated retainer with the first bearing, and the output shaft and the outer ring of the second bearing rotate synchronously. According to the friction transmission speed reducer, the technical means such as coaxial arrangement and retainer integrated design are adopted, so that the problems that an existing micro friction transmission speed reducer is complex in structure, high in machining difficulty, small in selectable range of the reduction ratio and the like are successfully solved; and the technical effects of more stable large torque output and higher transmission precision can still be achieved.

Description

Technical Field

[0001] The invention relates to a reducer, in particular to a friction transmission reducer. Background Art

[0002] With the continuous improvement of industrial automation and intelligence, high-precision manipulators (or high-precision robots) are increasingly used in modern industrial production. High-precision manipulators usually need to have high positioning accuracy and operational flexibility to simulate the movements of human hands and arms and accurately perform various complex tasks. In practical applications, in order to ensure the motion stability and accuracy of high-precision manipulators, their output ends usually need to have large torque and low speed to improve load capacity and control accuracy. Therefore, a deceleration mechanism is usually required between the drive source and the output component to reduce the output speed, increase the torque, and reduce motion errors, so that the manipulator can complete the given task more accurately.

[0003] At present, the reduction mechanism of high-precision manipulator mainly includes harmonic reducer, cycloid pinwheel reducer and traditional gear set reducer. Among them, the core structure of the harmonic reducer includes a wave generator, a flexible wheel and a rigid wheel. In the harmonic reducer, the wave generator drives the flexible wheel to rotate, so that the teeth of the flexible wheel and the teeth of the rigid wheel are meshed at two symmetrical positions, while other positions are disengaged. Moreover, since the number of teeth of the flexible wheel is less than that of the rigid wheel, when the wave generator rotates, the flexible wheel rotates slowly relative to the rigid wheel, thereby achieving a higher reduction ratio. The core structure of the cycloid pinwheel reducer includes an eccentric shaft, a cycloid wheel, a pinion housing and an output mechanism. Its working principle is to drive the cycloid wheel through the eccentric shaft, so that the cycloid wheel rotates around the eccentric axis, and at the same time, it is non-conjugatedly meshed with the pinion teeth in the pinion housing, thereby realizing a reduction transmission. The core structure of the traditional gear set reducer mainly includes involute gears, planetary gears (such as in the planetary reducer structure), central gears and gear racks. The gear reducer transmits power and achieves deceleration through the meshing relationship between gears. Its transmission accuracy depends on the processing accuracy and assembly accuracy of the gears.

[0004] However, with the increasing requirements of high-precision manipulators for miniaturization and high precision of the reduction mechanism, existing harmonic reducers, cycloid pinwheel reducers and traditional gear set reducers all have some problems in the miniaturization process.

[0005] First, after miniaturization, the harmonic reducer mainly relies on the meshing transmission between the flexible wheel and the rigid wheel. As a thin-walled component with elastic deformation ability, the flexible wheel needs to further reduce its wall thickness after miniaturization to ensure precise meshing with the rigid wheel. However, an over-thinned flexible wheel is prone to fatigue damage due to repeated deformation, resulting in a shortened service life. In addition, since the number of teeth on the flexible wheel is usually two less than that on the rigid wheel, its meshing accuracy is crucial to the overall performance of the reducer. After miniaturization, the manufacturing precision of the gears is required to be higher, and the processing difficulty increases significantly. At the same time, since the reduction ratio of the flexible wheel is limited by the tooth number ratio, under miniaturization conditions, the range of optional reduction ratios is narrow, which makes it difficult to meet the diverse needs of different application scenarios.

[0006] Secondly, after the cycloidal pinwheel reducer is miniaturized, the meshing accuracy of its core components, the cycloidal wheel and the pinion housing, is required to be extremely high. Especially for the eccentric structure of the cycloidal wheel, after miniaturization, the processing tolerance of its eccentricity becomes more stringent, and a slight error may lead to unstable transmission. In addition, the number of needle teeth in the pinion housing is large and densely distributed. During the miniaturization process, the reduction in the size of the needle teeth increases the difficulty of processing and reduces the load-bearing capacity, making it difficult for the cycloidal pinwheel reducer to maintain a high load capacity and reliability under miniaturization conditions. Furthermore, the reduction ratio of a miniature cycloidal pinwheel reducer usually depends on the difference in the number of teeth between the cycloidal wheel and the pinion teeth. After miniaturization, the range of optional reduction ratios becomes smaller, making it difficult to meet the needs of high-precision manipulators for multiple speed ratio configurations.

[0007] Finally, in the process of miniaturization of traditional gear reducers, due to the small module of the gears, the contact stress on the tooth surface increases after the size of the gears is reduced, which easily leads to increased wear on the tooth surface and affects the service life of the reducer. At the same time, the gear meshing transmission requires high processing accuracy. Under miniaturization conditions, the impact of gear processing errors on transmission efficiency and accuracy is more significant, resulting in a significant increase in manufacturing difficulty and cost. In addition, the reduction ratio of traditional gear reducers usually depends on the combined transmission of multiple gear stages. After miniaturization, due to space constraints, the number of gears that can be arranged is reduced, which limits the range of optional reduction ratios and makes it difficult to flexibly adapt to different working conditions.

[0008] In general, the existing harmonic reducers, cycloid reducers and traditional gear reducers all have certain technical bottlenecks in the process of miniaturization, which are mainly manifested in the increase of structural complexity, the increase of processing and manufacturing difficulty, the increase of manufacturing cost and the limited range of optional reduction ratios. Therefore, it is urgent to propose an optimized miniature reducer to solve the above problems. Summary of the invention

[0009] The object of the present invention is to provide a friction transmission reducer with compact structure, low manufacturing cost and flexible reduction ratio.

[0010] The technical solution adopted by the present invention to solve the above-mentioned problem is: a friction transmission reducer, including a shell, the shell including a accommodating space extending along a first direction, the accommodating space is provided with a first bearing and a second bearing coaxially arranged along the first direction, the first bearing and the second bearing both include an outer ring, an inner ring, a rolling element and a retaining frame.

[0011] The outer ring of the first bearing is fixedly connected to the housing, and the inner ring of the first bearing rotates in a controlled manner.

[0012] The inner ring of the second bearing rotates synchronously with the inner ring of the first bearing, and the retainer of the second bearing and the retainer of the first bearing are an integrated structure, so that the retainer of the second bearing rotates synchronously with the retainer of the first bearing when the reducer is running.

[0013] The friction transmission reducer also includes an output shaft, which is drivingly connected to the outer ring of the second bearing in a synchronously rotating manner.

[0014] Preferably, the first bearing is a deep groove ball bearing or a cylindrical roller bearing.

[0015] Preferably, the second bearing is a cylindrical roller bearing or a deep groove ball bearing.

[0016] Preferably, a friction transmission reducer also includes a third bearing for supporting the output shaft in the accommodating space, the third bearing is arranged on the side of the second bearing away from the first bearing in a coaxial arrangement with the second bearing, the third bearing also includes an inner ring, an outer ring, rolling elements and a retaining frame, the outer ring of the third bearing is fixedly connected to the outer housing, and the inner ring of the third bearing and the outer ring of the second bearing are an integrated structure.

[0017] Preferably, the third bearing is a four-point angular contact bearing.

[0018] Preferably, the housing further comprises a first opening and a second opening communicating with the accommodating space, the first opening and the second opening are arranged opposite to each other, and a line connecting the center of the first opening and the center of the second opening is parallel to the first direction.

[0019] The friction transmission reducer also includes: A first end cover, which is disposed at the first opening of the housing and abuts against the first end cover, wherein the first end cover further comprises a first communicating groove, and the first communicating groove is coaxially disposed with the inner ring of the first bearing; The second end cover is disposed at the second opening of the housing and abuts against the second end cover. The second end cover also includes a second communicating groove. The second communicating groove is coaxially disposed with the inner ring of the third bearing.

[0020] Preferably, a friction transmission reducer also includes a connecting bushing, which rotates in a controlled manner, is coaxially arranged with the first bearing, and is simultaneously transmission-connected to the inner ring of the first bearing and the inner ring of the second bearing, so that the inner ring of the first bearing and the inner ring of the second bearing rotate synchronously with the connecting bushing.

[0021] Preferably, the retaining frame of the second bearing is integrated with the retaining frame of the first bearing.

[0022] Preferably, the retainer of the second bearing is integrated with the retainer of the first bearing, and the inner ring of the third bearing is integrated with the outer ring of the second bearing.

[0023] Preferably, the first bearing is a deep groove ball bearing, the second bearing is a cylindrical roller bearing, and the retaining frame of the second bearing is integrated with the retaining frame of the first bearing.

[0024] The housing further includes a first opening and a second opening communicating with the accommodating space, the first opening and the second opening are arranged opposite to each other, and a line connecting the center of the first opening and the center of the second opening is parallel to the first direction.

[0025] The friction transmission reducer also includes: a third bearing, wherein the third bearing is a four-point angular contact bearing, and the third bearing is arranged coaxially with the second bearing on a side of the second bearing away from the first bearing, the outer ring of the third bearing is fixedly connected to the housing, and the inner ring of the third bearing is integrated with the outer ring of the second bearing; A first end cover, disposed at the first opening of the housing and abutting against the first end cover, the first end cover further comprising a first communicating groove, the first communicating groove being coaxially disposed with the inner ring of the first bearing; A second end cover is arranged at the second opening of the housing and abuts against a side of the second end cover, the second end cover further comprising a second communicating groove, and the second communicating groove is coaxially arranged with an inner ring of the third bearing; The connecting sleeve rotates in a controlled manner. The connecting sleeve is coaxially arranged with the first bearing and is simultaneously transmission-connected with the inner ring of the first bearing and the inner ring of the second bearing, so that the inner ring of the first bearing and the inner ring of the second bearing rotate synchronously with the connecting sleeve.

[0026] Beneficial effects of the embodiments of the present invention: 1. Since the present application adopts the method of cooperating the first bearing and the second bearing to achieve deceleration, it effectively solves the problems of complex structure, high processing difficulty and rising manufacturing cost of the micro reducer in the prior art. Moreover, because the structure of the bearing is relatively simple and the manufacturing process is mature, compared with the harmonic reducer, cycloid pinwheel reducer and traditional gear set reducer, its processing accuracy requirement is lower, thereby reducing the manufacturing difficulty and effectively reducing the production cost. In addition, the first bearing and the second bearing are transmitted through friction force to achieve the deceleration function, so that the friction transmission reducer of the present application does not need to rely on gear meshing or complex eccentric mechanism, making the adjustment of the reduction ratio more flexible. Different reduction ratios can be easily adjusted by replacing bearings of different models and different friction parameters without making major changes to the overall structure, thereby effectively solving the problem of limited optional range of reduction ratios of existing micro reducers and greatly expanding the applicable scenarios. Therefore, the present application provides a friction transmission reducer with a simple structure, low processing cost, a large adjustable range of reduction ratio and stable transmission by rationally utilizing the friction transmission characteristics of the bearing. It can effectively overcome the problems of high processing difficulty, high cost and limited reduction ratio range encountered by existing miniature reducers in the miniaturization process, making it more suitable for miniaturized and high-precision transmission application scenarios such as high-precision manipulators.

[0027] 2. Since the present application adopts a combination design in which the first bearing is a deep groove ball bearing, the second bearing is a cylindrical roller bearing, and the third bearing is a four-point angular contact bearing, the problems of bearing support stability, torque transmission capacity, and axial and radial force imbalance in the prior art micro reducer are effectively solved. First, the outer ring of the first bearing is fixedly connected to the outer shell, so that the running track of the rolling element of the first bearing is limited to the raceway of the deep groove ball bearing, thereby playing a precise positioning role for its own retainer and the second bearing retainer set in an integrated manner, effectively avoiding the axial deviation of the retainer beyond the limit, and improving the stability of the system operation. In addition, the second bearing adopts a cylindrical roller bearing, in which the rolling element is a short cylinder, and compared with the ball structure, its contact area is larger, so that the friction transmission capacity between the rolling element and the outer ring of the second bearing is enhanced, thereby improving the transmittable torque, so that the output torque of the output shaft is enhanced, and then the load capacity and overall transmission efficiency of the reducer are improved. Further, the third bearing adopts a four-point angular contact bearing, which can withstand axial force and radial force at the same time, thereby providing more stable support under miniaturization conditions. When the inner ring of the four-point angular contact bearing is connected to the outer ring of the cylindrical roller bearing as a whole, the outer ring of the second bearing is more stable during rotation, effectively reducing radial and axial shaking, and improving the overall operation stability of the reducer. Therefore, this application achieves precise positioning of the bearing, enhanced torque transmission capacity, and improved rotation stability by reasonably optimizing the bearing combination design, so that the reducer can maintain high-performance operation under miniaturized conditions and is suitable for high-precision transmission application scenarios such as high-precision manipulators. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic front cross-sectional view of a friction transmission reducer proposed in one embodiment of the present invention.

[0029] Figure 2 The schematic structure of the friction transmission reducer proposed in one embodiment of the present invention is Figure 1 .

[0030] Figure 3 The schematic structure of the friction transmission reducer proposed in one embodiment of the present invention is Figure 2 .

[0031] Figure 4 It is an exploded view of a friction transmission reducer proposed in one embodiment of the present invention.

[0032] Wherein: 10, friction transmission reducer; 110, housing; 111, accommodating space; 112, first opening; 113, second opening; 120, first bearing; 121, first inner ring; 122, first outer ring; 123, first retaining frame; 124, first rolling element; 130, second bearing; 131, second inner ring; 132, second outer ring; 133, second retaining frame; 134, second rolling element; 140, third bearing; 141, third inner ring; 142, third outer ring; 143, third retaining frame; 144, third rolling element; 150, output shaft; 160, first end cover; 161, first connecting groove; 170, second end cover; 171, second connecting groove; 180, connecting bushing. DETAILED DESCRIPTION

[0033] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0034] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the scope of protection of the present application. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description created by the present application, unless otherwise specified, "multiple" means two or more.

[0035] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood by specific circumstances.

[0036] Please refer to 1 to Figure 4 In a preferred embodiment of the present application, a friction transmission reducer 10 is proposed. The friction transmission reducer 10 is a miniature reducer suitable for installation in equipment or devices with limited installation space and requiring a compact layout. Such equipment or devices can be high-precision robotic arms, which are not specifically limited here and depend on the usage.

[0037] The friction transmission reducer 10 includes a housing 110, a first bearing 120, a second bearing 130 and an output shaft 150. The housing 110 includes a housing space 111 extending in a first direction, the first bearing 120 and the second bearing 130 are both installed in the housing space 111, and the first bearing 120 and the second bearing 130 are coaxially arranged in the first direction, and the first bearing 120 and the second bearing 130 each include an outer ring, an inner ring, a rolling element and a retainer. The outer ring of the first bearing 120 is fixedly connected to the housing 110, and the inner ring of the first bearing 120 rotates in a controlled manner. The inner ring of the second bearing 130 rotates synchronously with the inner ring of the first bearing 120, and the retainer of the second bearing 130 is an integrated structure with the retainer of the first bearing 120. When the reducer is running, the retainer of the second bearing 130 rotates synchronously with the retainer of the first bearing 120. The output shaft 150 is drivingly connected to the outer ring of the second bearing 130 in a synchronously rotating manner.

[0038] It should be noted that, in order to facilitate the distinction between the various parts in the first bearing 120 and the second bearing 130, the inner ring of the first bearing 120 is defined as the first inner ring 121, the inner ring of the second bearing 130 is defined as the second inner ring 131, the outer ring of the first bearing 120 is defined as the first outer ring 122, the outer ring of the second bearing 130 is defined as the second outer ring 132, the retaining frame of the first bearing 120 is defined as the first retaining frame 123, the retaining frame of the second bearing 130 is defined as the second retaining frame 133, the rolling element of the first bearing 120 is defined as the first rolling element 124, and the rolling element of the second bearing 130 is defined as the second rolling element 134.

[0039] Specifically, the friction transmission device forms a compact and efficient micro-reduction structure by coaxially arranging the first bearing 120 and the second bearing 130 in the accommodating space 111 of the housing 110, meeting the use requirements of limited installation space and compact layout.

[0040] The size and shape of the housing 110 can be designed according to the installation environment, and can be embodied in a cylinder, a cuboid, etc., with a cylinder as an example, as shown in Figure 1 to Figure 2. The housing 110 has a housing space 111 inside it to provide installation space for the first bearing 120 and the second bearing 130, and the housing 110 provides effective protection for the first bearing 120 and the second bearing 130. The housing 111 is formed in the housing along a first direction, wherein the first direction is usually axial, and the shape of the housing 111 can be selected as a cylindrical structure that matches the shape of the outer ring of the bearing in order to meet the requirements of limited installation space and compact layout, so that when the first bearing 120 and the second bearing 130 are installed in the housing space 111, the outer side of the first outer ring 122 fits the inner wall of the housing space 111, making the friction transmission reducer 10 more compact. The connection between the first bearing 120 and the housing 110 is specifically embodied as interference fit or connection through fasteners. Taking interference fit as an example, the first outer ring 122 is expanded with the inner wall of the accommodating space 111, so that the first bearing 120 is fixedly installed inside the housing 110. The housing 110 is preferably made of high-strength materials, such as metal alloys, composite materials, etc., to ensure good durability and rigidity in applications such as high-precision robotic arms. It should be noted that the housing 110 is usually in a stationary state when the friction transmission reducer 10 is running.

[0041] The first bearing 120 and the second bearing 130 are the main components of the friction transmission reducer 10. The two cooperate to control the rotation speed of the output shaft 150. In order to meet the requirements of compact layout and limited installation space, the first bearing 120 and the second bearing 130 can be miniature bearings to adapt to the limited installation space. The type of the first bearing 120 and the second bearing 130 is a deep groove ball bearing or a cylindrical roller bearing. For example, the first bearing 120 is a deep groove ball bearing and the second bearing 130 is a cylindrical roller bearing. Figure 1 and Figure 4 As shown, the outer ring of the deep groove ball bearing is interference fit with the inner wall of the housing 110, and the inner ring of the deep groove ball bearing and the inner ring of the cylindrical roller bearing are both drivingly connected to the rotating shaft of the motor, so that when the motor is running, the inner ring of the deep groove ball bearing and the inner ring of the cylindrical roller bearing can rotate in a controlled manner along with the rotating shaft of the motor.

[0042] When the first bearing 120 is a deep groove ball bearing and the second bearing 130 is a cylindrical roller bearing, the rolling element of the deep groove ball bearing is confined in the annular rolling groove formed by the inner ring raceway and the outer ring raceway, thereby limiting the position of the retainer of the deep groove ball bearing, so that when the rolling element of the cylindrical roller bearing moves around, the axial movement is limited by the retainer of the deep groove ball bearing integrated with the retainer, so that the distance of the retainer of the cylindrical roller bearing moving axially is within the allowable range. The rolling element of the cylindrical roller bearing is a plurality of short cylinders, and the contact area between the short cylinders and the inner ring and the outer ring is much larger than that of the ball, which can increase the friction between the rolling element and the outer ring, thereby improving the torque of the output shaft 150. Furthermore, because the movement of the rolling elements in the deep groove ball bearing can be regarded as pure rolling operation, in this case, the rolling elements of the deep groove ball bearing can push its retaining frame to rotate in the same direction, and because the first retaining frame 123 and the second retaining frame 133 are an integrated structure, when the retaining frame of the deep groove ball bearing rotates, the retaining frame of the cylindrical roller bearing will also rotate synchronously, so that the rolling elements of the cylindrical roller bearing will also move under the action of its own retaining frame and inner ring. At this time, the outer ring of the cylindrical roller bearing will rotate accordingly relative to the inner ring due to the friction contact of its own rolling elements, and the rotation speed of the cylindrical roller bearing will be lower than the rotation speed of its inner ring and the rotation speed of the deep groove ball bearing.

[0043] The integrated structure can be specifically embodied as integrated forming or connecting two parts into one through a connector. Taking integrated forming as an example, Figure 1 and Figure 4 As shown, the first retaining frame 123 and the second retaining frame 133 are integrally formed during the manufacturing process by stamping, precision casting, powder metallurgy, 3D printing, CNC machining, or cold heading.

[0044] The reason why the first bearing 120 and the second bearing 130 can form a reduction ratio is that the bearings have a certain contact angle and friction characteristics, and the speed of the second outer ring 132 relative to the first inner ring 121 and the second inner ring 131 will be reduced, thereby forming the required reduction ratio. When the friction transmission reducer 10 is in operation, the torque is transmitted through the rolling or friction of the rolling elements, and the high speed input is converted into a low speed output. The output shaft 150 is connected to the second outer ring 132, so the reduced rotation of the outer ring of the second bearing 130 is directly transmitted to the output shaft 150, so that the external load obtains the required torque and speed.

[0045] The relationship between the speed of the inner ring of the bearing, the speed of the outer ring and the speed of the cage can be determined by the following formula: .

[0046] Among them, the coefficient The expression is: .

[0047] The meaning of each symbol is: : Cage speed (unit: r / min).

[0048] : Inner ring speed (unit: r / min).

[0049] : Outer ring speed (unit: r / min).

[0050] : The diameter of the rolling element.

[0051] : Contact angle between rolling element and raceway.

[0052] : The center diameter of the cage is also called the "pitch circle diameter" (that is, the diameter of the trajectory circle formed by the center of the rolling element in the axial section, which can generally be understood as the rolling element distribution circle diameter of the bearing).

[0053] “ ": Determined by whether the inner and outer rings rotate in the same or opposite directions. When the inner and outer rings rotate in opposite directions, " ", when the inner and outer rings rotate in the same direction, select " ”.

[0054] During the operation of the rolling bearing, the rolling elements roll in contact with both the inner ring and the outer ring. When both the inner ring and the outer ring are in a rotating state (for example, the inner ring rotates with the shaft, and the outer ring also rotates due to load or transmission requirements), the rolling elements will produce compound rolling and self-rotation due to the different linear speed differences at both ends. The main function of the cage is to evenly distribute the rolling elements around the raceway and avoid collisions between the rolling elements. Therefore, the speed of the cage is often between the speed of the inner ring and the speed of the outer ring, which depends on the speed of the inner ring and the outer ring and their rotation direction.

[0055] Because the linear velocity of the rolling element at the contact point between the inner and outer rings is equal (no sliding or micro-slip assumption), the angular velocity of the rolling element can be related to the angular velocity of the inner and outer rings. , contact angle and the pitch circle diameter at the center It will affect the kinematic geometric relationship between the rolling element and the cage, so the Considering the constraints between the cage and the rolling element in the circumferential direction, it can be obtained that the speed of the cage is often a linear combination of the inner ring speed and the outer ring speed, and the coefficient appears .

[0056] When the inner ring and outer ring rotate in the same direction or in opposite directions, the direction of the resultant force on the corresponding cage and the motion state of the rolling elements will be slightly different, so there is a " " symbol to distinguish different combinations of rotation directions.

[0057] The meaning of each part in the above formula is as follows: 1 / 2 is a "compromise value" for the cage speed, usually between the speeds of the inner and outer rings. From the technical documentation, we know that if only the inner ring rotates and the outer ring is fixed (i.e. ), the cage speed is about half of the inner ring speed (specifically, it depends on to perform the calculation).

[0058] and These two items correspond to the speed effects of the rolling elements on the inner and outer rings. If we consider the large rolling element diameter, large contact angle or small cage center diameter (resulting in The larger the value), the more "active" the rolling elements will be between the inner and outer rings, making the cage's speed change more significant. The closer it is to 0, the weaker the influence between rolling element size, contact angle and pitch circle diameter. At this time, the cage speed is close to the pure geometric mean state.

[0059] The above formula is applied in this embodiment as follows: During the operation of the motor of the device, the rotating shaft of the motor is the input end, and its rotation speed can be regarded as a known quantity, and the first inner ring 121 and the second outer ring 132 are fixedly sleeved on the rotating shaft of the motor, so the rotation speed of the first inner ring 121 and the second inner ring 131 are equal to the rotation speed of the rotating shaft of the motor and have the same rotation direction. The first outer ring 122 is fixedly connected to the housing 110, and the housing 110 is stationary when the friction transmission reducer 10 is in operation, so the rotation speed of the outer ring of the bearing is 0. At this time, by consulting the parameter information of the first bearing 120 (rolling element diameter, contact angle and cage center diameter), the rotation speed of the cage of the first bearing 120 can be calculated by the above formula. Furthermore, because the first inner ring 121 and the second outer ring 132 are both fixedly sleeved on the rotating shaft of the motor, and the first retaining frame 123 and the second retaining frame 133 are integrated structures, the two inner rings can be regarded as a whole. Similarly, the two retaining frames can also be regarded as a whole. At this time, the rotation speed of the motor rotating shaft is the rotation speed of the integral inner ring, and the rotation speed of the first bearing 120 retaining frame is the rotation speed of the integral retaining frame. On the basis that the rotation speed of the integral inner ring and the rotation speed of the integral retaining frame are known, the rotation speed of the second outer ring 132 can be obtained by substituting them into the above formula.

[0060] The output shaft 150 is connected to the second outer ring 132 in a transmission manner to achieve a rotational speed output. When working, the output shaft 150 is coupled or matched with an external device (such as a mechanical arm joint, a motor transmission mechanism, etc.). The size, length and cross-sectional shape of the output shaft 150 can be flexibly designed according to application requirements to adapt to precise installation and fixation in a compact space.

[0061] The friction transmission reducer 10 in this embodiment has the characteristics of small size and compact structure. By integrating the first bearing 120 and the second bearing 130 in the same axial space and adopting an integrated cage design, a high degree of integration of the reduction structure is achieved, which saves assembly space and is suitable for micro-devices or devices with strict requirements on the external dimensions and installation position. Secondly, relying on the rolling contact or controlled friction between the outer ring and the inner ring of the rolling body, a smooth and efficient reduction is achieved. Compared with the traditional gear reducer, the number of parts is relatively reduced, the meshing clearance is smaller, and the operation accuracy is higher. Furthermore, the first bearing 120 and the second bearing 130 are independent of the housing 110, the output shaft 150 and other components and are modularly designed. When a problem occurs, only the faulty components need to be repaired or replaced separately. The overall structure is simple, no complicated gear meshing adjustment is required, and daily maintenance and lubrication are relatively easy. Therefore, compared with the reducer traditionally used in the mechanical arm, the friction transmission reducer 10 has the advantages of small size, simple structure, convenient processing and a wide range of reduction ratio options.

[0062] It should be noted that the friction transmission reducer 10 proposed in this embodiment can also adjust the reduction ratio to a large extent according to the usage scenario based on the above formula. In traditional micro reducers, gears or worm gears are usually used for transmission. Although they can provide a certain reduction ratio, their adjustment range is limited by the meshing angle, number of teeth, transmission method, etc. of the gears, and usually produce greater friction and vibration. In the friction transmission reducer 10 using the first bearing 120 and the second bearing 130, the introduction of parameters (rolling element diameter, contact angle and cage center diameter) provides greater flexibility and range for adjusting the reduction ratio. The following is a specific analysis: coefficient This coefficient determines the relationship between the relative speed between the inner ring and the outer ring and the cage speed. , contact angle and the center diameter of the cage , this coefficient can be adjusted flexibly. A larger coefficient Corresponding to the larger rolling element diameter , Larger contact angle or smaller cage center diameter , thus affecting the adjustment range of the reduction ratio. At this time, the speed change of the cage is more significant, and a larger reduction ratio adjustment can be achieved. Involving multiple adjustable parameters, the reduction ratio can also be precisely adjusted as needed.

[0063] The geometric relationship between the rolling element and the cage (such as rolling element diameter, contact angle, etc.). Since the geometric structure of the rolling element and the cage has an important influence on the reduction ratio, reasonable design of the rolling element diameter and contact angle can effectively change coefficient, thus affecting the wide range of the reduction ratio. For example, increasing the diameter or contact angle of the rolling element can increase the speed range of the cage, thereby increasing the flexibility of the reduction ratio adjustment.

[0064] Cage center diameter Affects the matching relationship between rolling elements and cages, while smaller The value can make the speed of the cage vary more, thus providing a larger reduction ratio adjustment space.

[0065] In summary, compared with the traditional micro reducer, the design using the first bearing 120 and the second bearing 130 has a wider range of speed reduction ratio adjustment, and the speed reduction ratio can be flexibly adjusted by adjusting parameters such as the rolling element diameter, contact angle and cage center diameter. In addition, the geometric parameters such as the rolling element diameter and contact angle can be optimized to make the cage speed change range wider, thereby expanding the adjustment space of the speed reduction ratio. Therefore, the friction transmission reducer 10 proposed in this embodiment has stronger adaptability and adjustability in application than the traditional reducer, and can meet the requirements for speed reduction ratio in a variety of different application scenarios.

[0066] In some embodiments, Figure 1 As shown, in order to keep the output shaft 150 in stable rotation during the rotation process, the friction transmission reducer 10 also includes a third bearing 140 for supporting the output shaft 150 in the accommodating space 111, and the third bearing 140 is arranged in a coaxial manner on the side of the second bearing 130 away from the first bearing 120, and the third bearing 140 also includes an inner ring, an outer ring, a rolling element and a retaining frame, and the third outer ring 142 is fixedly connected to the housing 110, and the third inner ring 141 and the second outer ring 132 are an integrated structure. Further, in some embodiments, the third bearing 140 is a four-point angular contact bearing.

[0067] Specific: The friction transmission reducer 10 is designed with multiple important bearing components, among which the addition of the third bearing 140 plays a key role in improving the stability of the system.

[0068] The output shaft 150 must keep rotating smoothly during the rotation process to avoid vibration or transmission error caused by the deviation or instability of the shaft. In order to achieve this, the friction transmission reducer 10 introduces a third bearing 140 to support the output shaft 150 and ensure that it remains stable in the accommodating space 111. The third bearing 140 is coaxially arranged with the second bearing 130 and is arranged on the side of the second bearing 130 away from the first bearing 120. In this way, the third bearing 140 can further stabilize the position of the output shaft 150 and prevent the output shaft 150 from swinging due to changes in axial force or radial force. The structure of the third bearing 140 is similar to that of the first bearing 120 and the second bearing 130, and is also composed of an inner ring, an outer ring, rolling elements and a retainer. The third outer ring 142 is fixedly connected to the housing 110, and the third inner ring 141 is integrally connected to the outer ring of the second bearing 130.

[0069] In order to facilitate the distinction between the components of the third bearing 140 and the first bearing 120 and the second bearing 130, the third inner ring 141 is defined as a third inner ring 141, the third outer ring 142 is defined as a third outer ring 142, the third retaining frame 143 is defined as a third retaining frame 143, and the third rolling element 144 is defined as a third rolling element 144.

[0070] The third bearing 140 adopts a four-point angular contact bearing, which can bear loads from multiple directions at the same time, including axial and radial loads. This design improves the load-bearing capacity and stability of the system under high load conditions, especially under high-speed operation, and can effectively reduce unnecessary vibration and improve transmission accuracy. Due to the characteristics of its contact angle, the four-point angular contact bearing can work under multi-directional loads, so it can reduce offset and wear while ensuring the high-efficiency operation of the friction transmission reducer 10.

[0071] The working principle of the friction transmission reducer 10 is that the first bearing 120, the second bearing 130 and the third bearing 140 work together to optimize the rotation and bearing capacity between the inner ring, the outer ring and the output shaft 150, and the output shaft 150 always maintains stable rotation. In the specific friction transmission deceleration process, the third bearing 140 supports the output shaft 150 on the side of the second bearing 130 away from the first bearing 120 through an integrated design with the outer ring of the second bearing 130, further enhancing the stability of the output shaft 150. Moreover, since the third bearing 140 adopts a four-point angular contact bearing design, it can effectively withstand multi-directional loads, so that the output shaft 150 can still maintain stable rotation under high load and high-speed operation.

[0072] In this embodiment, by introducing the third bearing 140 to support the output shaft 150 and adopting the design of the four-point angular contact bearing, it is possible to bear loads in multiple directions at the same time, so that the reducer can maintain good performance under high loads and adapt to complex and heavy-load working environments. In addition, the four-point angular contact bearing can also significantly improve the stability of the output shaft 150, reduce the vibration and offset of the shaft, and ensure the long-term stable operation of the system. Moreover, due to the structural design of the friction transmission reducer 10, a flexible reduction ratio adjustment range can be provided under different load and speed conditions. The addition of the third bearing 140 helps to maintain a stable output under different working conditions and avoid output instability caused by load changes. Therefore, the introduction of the third bearing 140 significantly improves the stability and load-bearing capacity of the friction transmission reducer 10, and at the same time increases the adaptability and adjustment ability of the reducer under different loads and speeds. This enables the reducer to maintain excellent performance under complex and high-load environments. The design of the friction transmission reducer 10 is suitable for a variety of equipment with limited space but high requirements for stability and high precision, and can be used in a wide range of industries, including robots, automated production lines, precision instruments, etc.

[0073] It should be noted that when the third inner ring 141 and the second outer ring 132 adopt an integrated design, the second outer ring 132 and the third inner ring 141 are actually integrated into the same component, which in the present application has the effects of reducing the number of components to simplify the assembly structure, reducing the coaxiality error to improve the transmission accuracy, reducing the assembly clearance to improve the rigidity and stability, shortening the axial dimension to achieve a more compact layout and reducing the friction loss caused by assembly and matching errors.

[0074] Traditional multi-bearing layouts often require a separate second bearing 130 outer ring and a third bearing 140 inner ring, and fit, position or fasten them. The integrated design combines two independent parts into one whole, with fewer parts, simpler part fit and axial positioning during assembly, and more reliable assembly process.

[0075] It is easy for multiple independent parts to have coaxial deviations due to manufacturing or assembly errors, which in turn causes vibration, runout, eccentricity, etc. When the second outer ring 132 and the third inner ring 141 are directly made into one piece, the contact surface that originally needs to be matched is eliminated, the structure is more compact, and the coaxiality of the two bearings in the axial and radial directions is naturally guaranteed, thereby improving the overall transmission accuracy.

[0076] Usually, two independent parts need to have assembly tolerance or matching transition zone, which may cause a small gap or play. The integrated design eliminates such tolerance matching, and can further reduce the gap and improve the system rigidity under the premise of the same material and processing accuracy, so that the output shaft 150 can still maintain stable rotation under high speed and high load conditions.

[0077] In mechanical systems, axial space is often very valuable. By combining the outer ring of the second bearing 130 and the inner ring of the third bearing 140 into one piece, the overall axial length can be shortened and a compact design can be achieved. This is particularly important for applications with limited space or sensitive to volume and weight (such as micro-robotic arms, precision instruments, etc.).

[0078] In some embodiments, Figure 4 As shown, in order to facilitate the assembly of the friction transmission reducer 10 in the present application, the housing 110 further includes a first opening 112 and a second opening 113 that are connected to the accommodating space 111, the first opening 112 and the second opening 113 are arranged opposite to each other, and the line connecting the center of the first opening 112 and the center of the second opening 113 is parallel to the first direction. Furthermore, in order to prevent the first bearing 120 or the third bearing 140 from falling out of the housing 110 during the operation of the friction transmission reducer 10, the friction transmission reducer 10 further includes a first end cover 160 and a second end cover 170. The first end cover 160 is arranged at the first opening 112 of the housing 110 and abuts against the side of the first end cover 160 facing the housing 110, and the first end cover 160 further includes a first connecting groove 161, and the first connecting groove 161 is arranged coaxially with the first inner ring 121. The second end cover 170 is disposed at the second opening 113 of the housing 110 and abuts against a side of the second end cover 170 facing the housing 110 . The second end cover 170 further includes a second communicating groove 171 , which is coaxially disposed with the third inner ring 141 .

[0079] Specifically, in order to facilitate the assembly of the friction transmission reducer 10, the first opening 112 and the second opening 113 are introduced into the design of the housing 110. The first opening 112 and the second opening 113 are arranged opposite to each other, and the design that their center line is parallel to the first direction makes it possible to easily install the first bearing 120, the second bearing 130 and the third bearing 140 in the housing 110 through the two openings during the assembly of the reducer. Specifically, during assembly, each bearing can be installed into the housing 110 through the two openings, and the correct docking of the bearings can be ensured. Moreover, due to the relative design of the first opening 112 and the second opening 113, the assembly efficiency of the bearings can be improved, multiple adjustments and inspections can be avoided, and the convenience of assembly is improved.

[0080] In some embodiments, Figure 4As shown, in order to prevent the first bearing 120 or the third bearing 140 from falling out of the housing 110 during the operation of the friction transmission reducer 10, the first end cover 160 and the second end cover 170 are introduced into the design. The first end cover 160 and the second end cover 170 are respectively arranged at the first opening 112 and the second opening 113 of the housing 110, and the sides respectively in contact with the housing 110 face the housing 110. The two end covers not only fix the bearings in the housing 110, but also ensure that the bearings will not fall out of the housing 110 due to excessive speed or axial force when the reducer is running. Specifically, through the arrangement of the first end cover 160 and the second end cover 170, the first inner ring 121 and the third inner ring 141 are respectively fixed to the housing 110 by the first end cover 160 and the second end cover 170 through the connecting groove. The connection between the first end cover 160 and the inner ring of the first bearing 120 and the second end cover 170 and the inner ring of the second bearing 130 ensures that the first bearing 120 and the second bearing 130 can maintain stable positioning even during high load or high speed operation.

[0081] Furthermore, in order to ensure the convenience of power input and output, the first end cover 160 and the second end cover 170 are also provided with a first connecting groove 161 and a second connecting groove 171 respectively. In addition, the first connecting groove 161 and the second connecting groove 171 are coaxially arranged with the inner ring of the first bearing 120 and the inner ring of the third bearing 140, thereby ensuring the precise docking of the bearings, so that the bearings can stably transfer the load without displacement during operation. This design can effectively reduce the problem of the bearings falling off due to the axial force, radial force or other forces during the rotation process.

[0082] In this embodiment, firstly, the assembly process is simplified by setting the first opening 112 and the second opening 113, making the assembly more intuitive and efficient. Secondly, by introducing the first end cover 160 and the second end cover 170, and the design of the first connecting groove 161 and the second connecting groove 171, the problem of each bearing coming out of the housing 110 is successfully avoided. Through this design, each bearing is fixed more firmly, and the reliability of the friction transmission reducer 10 during operation is improved. Then, the first bearing 120 and the third bearing 140 and the housing 110 are stably assembled through the clamping effect of the first end cover 160 and the second end cover 170, so that the friction transmission reducer 10 can maintain a good operating state under high load and high-speed operation conditions. Therefore, by designing the first opening 112, the second opening 113, the first end cover 160, the second end cover 170, the first connecting groove 161 and the second connecting groove 171 structure for the friction transmission reducer 10, not only the assembly process is optimized and the assembly efficiency is improved, but also the problems of bearing coming out and system stability are effectively solved. The overall friction transmission reducer 10 further improves the operating efficiency and reliability of the reducer by reducing the number of parts, improving the stability of bearings, and reducing assembly clearances. It is particularly suitable for application scenarios with high requirements for stability and precision.

[0083] In some embodiments, Figure 1 As shown, sometimes there is a difference between the size of the rotating shaft of the motor in the device and the inner diameter of the first inner ring 121 and the second inner ring 131 in the friction transmission reducer 10. Therefore, in order to enable the first inner ring 121 and the second inner ring 131 to rotate synchronously with the rotating shaft of the external motor, the friction transmission reducer 10 also includes a connecting bushing 180, and the connecting bushing 180 rotates in a controlled manner. The connecting bushing 180 is coaxially arranged with the first bearing 120, and the connecting bushing 180 is connected to the first inner ring 121 and the second inner ring 131 at the same time, so that the first inner ring 121 and the second inner ring 131 both rotate synchronously with the connecting bushing 180.

[0084] Specifically, in the design of the friction transmission reducer 10, the size of the rotating shaft of the external motor may not completely match the inner diameter of the first bearing 120 and the second inner ring 131 in the friction transmission reducer 10, resulting in direct connection and other problems such as poor assembly, unstable transmission or reduced efficiency. Therefore, the design of the connecting bushing 180 is introduced to enable the first inner ring 121 and the second inner ring 131 to rotate synchronously with the rotating shaft of the external motor, thereby solving this problem. The shape structure of the connecting bushing 180 is embodied in a specific manner as a ring member, which can be sleeved on the rotating shaft of the motor by an interference fit, and the outer surface of the ring member is divided into two parts, one part is interference fit with the first inner ring 121, and the other part is interference fit with the second inner ring 131.

[0085] The size of the rotating shaft of the external motor may be slightly larger or smaller than the inner diameter of the inner ring of the first bearing 120 and the second bearing 130 in the friction transmission reducer 10. The connecting bushing 180 ensures that the rotating shaft of the external motor and the inner ring of the bearing can be effectively connected by designing appropriate inner and outer diameter sizes, thereby achieving synchronous rotation. In addition, the connecting bushing 180, as a transition part, can provide precise matching between different parts, so that the parts that originally do not match in size can be stably connected and work together. Moreover, by using the connecting bushing 180, the friction resistance or transmission error caused by size mismatch is avoided. The connecting bushing 180 is coaxially arranged with the first bearing 120 and the second inner ring 131, and is connected to them at the same time, thereby ensuring that the first bearing 120 and the second inner ring 131 can rotate synchronously. This means that the rotating shaft of the external motor and the inner ring of the bearing inside the reducer can rotate together without sliding, thereby achieving smooth power transmission. Further, through the stable connection of the connecting bushing 180, the first bearing 120 and the second inner ring 131 will not slide relative to each other, thereby avoiding the possible problems of reduced transmission efficiency and increased wear. Furthermore, by using the connecting bushing 180, the assembly process can be simplified, and there is no need to make complicated adjustments to the motor shaft or the inner ring of the bearing, making the assembly process more efficient and reliable.

[0086] Since the size of the rotating shaft of the external motor and the inner diameter of the inner ring of the bearing may not completely match, the connecting bushing 180 fills the size difference by designing a reasonable size and shape, so that the two parts can be smoothly connected together. The material and precision of the connecting bushing 180 usually need to be specially designed to ensure that it can work stably under different working conditions.

[0087] In this example, by introducing the design of the connecting bushing 180, the friction transmission reducer 10 can effectively solve the matching problem between the size of the external motor rotating shaft and the inner ring of the bearing, and achieve accurate power transmission and stable rotation effect. In addition, the design of the connecting bushing 180 ensures the synchronous rotation of the inner ring of the bearing and the rotating shaft, improves the stability, efficiency and durability of the transmission system, simplifies the assembly process, and avoids technical problems caused by size differences. Therefore, the design of the connecting bushing 180 is of great significance to improving the overall performance of the friction transmission reducer 10.

[0088] The above contents described in this specification are merely examples of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, as long as they do not deviate from the contents of the present specification or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.

Claims

1. A friction transmission reducer, characterized in that: The housing comprises a housing, wherein the housing comprises a housing space extending along a first direction, wherein a first bearing and a second bearing coaxially arranged along the first direction are arranged in the housing space, wherein the first bearing and the second bearing each comprise an outer ring, an inner ring, a rolling element and a retaining frame; The outer ring of the first bearing is fixedly connected to the housing, and the inner ring of the first bearing rotates in a controlled manner; The inner ring of the second bearing rotates synchronously with the inner ring of the first bearing, and the retainer of the second bearing and the retainer of the first bearing are an integrated structure, so that the retainer of the second bearing rotates synchronously with the retainer of the first bearing when the reducer is running; The friction transmission reducer also includes an output shaft, which is drivingly connected to the outer ring of the second bearing in a synchronously rotating manner.

2. A friction transmission reducer according to claim 1, characterized in that: The first bearing is a deep groove ball bearing or a cylindrical roller bearing.

3. A friction transmission reducer according to claim 1, characterized in that: The second bearing is a cylindrical roller bearing or a deep groove ball bearing.

4. A friction transmission reducer according to claim 1, 2 or 3, characterized in that: It also includes a third bearing for supporting the output shaft in the accommodating space. The third bearing is arranged on a side of the second bearing away from the first bearing in a coaxial arrangement with the second bearing. The third bearing also includes an inner ring, an outer ring, rolling elements and a retaining frame. The outer ring of the third bearing is fixedly connected to the outer housing, and the inner ring of the third bearing and the outer ring of the second bearing are an integrated structure.

5. A friction transmission reducer according to claim 4, characterized in that: The third bearing is a four-point angular contact bearing.

6. A friction transmission reducer according to claim 5, characterized in that: The housing further includes a first opening and a second opening communicating with the accommodating space, the first opening and the second opening are arranged opposite to each other, and a line connecting the center of the first opening and the center of the second opening is parallel to the first direction; The friction transmission reducer also includes: A first end cover, which is disposed at the first opening of the housing and abuts against the first end cover, wherein the first end cover further comprises a first communicating groove, and the first communicating groove is coaxially disposed with the inner ring of the first bearing; The second end cover is disposed at the second opening of the housing and abuts against the second end cover. The second end cover also includes a second communicating groove. The second communicating groove is coaxially disposed with the inner ring of the third bearing.

7. A friction transmission reducer according to claim 1, 5 or 6, characterized in that: It also includes a connecting sleeve, which rotates in a controlled manner, is coaxially arranged with the first bearing, and is simultaneously transmission-connected to the inner ring of the first bearing and the inner ring of the second bearing, so that the inner ring of the first bearing and the inner ring of the second bearing rotate synchronously with the connecting sleeve.

8. The friction transmission reducer according to claim 1, characterized in that: The retainer of the second bearing is integrated with the retainer of the first bearing.

9. A friction transmission reducer according to claim 4, characterized in that: The retainer of the second bearing is integrated with the retainer of the first bearing, and the inner ring of the third bearing is integrated with the outer ring of the second bearing.

10. A friction transmission reducer according to claim 1, characterized in that: The first bearing is a deep groove ball bearing, the second bearing is a cylindrical roller bearing, and the retainer of the second bearing is integrated with the retainer of the first bearing; The housing further includes a first opening and a second opening communicating with the accommodating space, the first opening and the second opening are arranged opposite to each other, and a line connecting the center of the first opening and the center of the second opening is parallel to the first direction; The friction transmission reducer also includes: a third bearing, wherein the third bearing is a four-point angular contact bearing, and the third bearing is arranged coaxially with the second bearing on a side of the second bearing away from the first bearing, the outer ring of the third bearing is fixedly connected to the housing, and the inner ring of the third bearing is integrated with the outer ring of the second bearing; A first end cover, disposed at the first opening of the housing and abutting against the first end cover, the first end cover further comprising a first communicating groove, the first communicating groove being coaxially disposed with the inner ring of the first bearing; A second end cover is arranged at the second opening of the housing and abuts against a side of the second end cover, the second end cover further comprising a second communicating groove, and the second communicating groove is coaxially arranged with an inner ring of the third bearing; The connecting sleeve rotates in a controlled manner. The connecting sleeve is coaxially arranged with the first bearing and is simultaneously transmission-connected with the inner ring of the first bearing and the inner ring of the second bearing, so that the inner ring of the first bearing and the inner ring of the second bearing rotate synchronously with the connecting sleeve.

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