Robot joint radial pre-tightening cycloid speed reducer

Abstract

The invention discloses a radial pre-tightening cycloidal speed reducer for a robot joint. The radial pre-tightening cycloidal speed reducer comprises a shell, a flange assembly, an input shaft with double eccentric sleeves, cycloidal gears, pin gears, radially deformable pin gears and a radial pre-tightening assembly, wherein the flange assembly, the input shaft, the cycloidal gears, the pin gears and the radial pre-tightening assembly are mounted in the shell; the radial pre-tightening assembly is tightly arranged on the outer contour face of the radially-deformable pin wheel in a sleeving mode and continuously applies radial pre-tightening force to the radial-deformable pin wheel, and when a wear gap exists between the pin teeth and the cycloidal gear, the radial pre-tightening assembly drives the inner contour face of the radial pre-tightening assembly to press the radially-deformable pin wheel; the outer contour surface, close to the cycloidal gear, of the radially-deformable pin gear elastically shrinks inwards in the radial direction, the pin teeth are driven to move in the radial direction in the cycloidal gear direction, and therefore the abrasion clearance is eliminated. The two ends of the pin teeth are installed between the pin wheels capable of being deformed in the radial direction, the outer contour faces of the pin wheels are sleeved with the radial pre-tightening assemblies for continuously applying pre-tightening force, self-adaptive dynamic compensation of abrasion gaps is achieved, and the transmission precision maintaining capacity of the speed reducer in the whole life cycle is improved.

Description

Technical Field

[0001] This invention relates to a radial preloaded cycloidal reducer for robot joints, belonging to the field of reducer technology. Background Technology

[0002] Cycloidal reducers utilize the eccentric motion between the cycloidal wheel and the pin gear to achieve differential gear transmission, featuring a large reduction ratio and high transmission accuracy. With the development of humanoid robot technology, cycloidal reducers are increasingly widely used in key components such as the lower limb joints, hip joints, and shoulder joints of humanoid robots, placing higher demands on the reducer's initial accuracy and its ability to maintain accuracy during long-term service. However, during prolonged operation, external factors such as load and impact, coupled with the inherent eccentric motion characteristics between the cycloidal wheel and the pin gear, inevitably cause wear between the cycloidal wheel and the pin gear. As service time increases, the clearance between the cycloidal wheel and the pin gear gradually increases, leading to a continuous decline in the transmission accuracy of the cycloidal reducer, ultimately making it difficult to meet the requirements of high-precision applications. Summary of the Invention

[0003] Purpose of the invention: To address the shortcomings of existing technologies, this invention provides a radially preloaded cycloidal reducer for robot joints. This invention uses a radially preloaded component to drive a radially deformable pinwheel to elastically contract, dynamically compensating for wear gaps and maintaining long-term transmission accuracy.

[0004] Technical solution: A cycloidal reducer with radial preload for robot joints, comprising a housing and a flange assembly installed within the housing, an input shaft with a double eccentric sleeve, a cycloidal wheel, pin teeth, a radially deformable pin wheel, and a radial preload assembly;

[0005] Two sets of radially deformable needle wheels are arranged opposite each other along the axial direction. The two ends of the needle teeth are respectively connected to the opposite surfaces of the two radially deformable needle wheels. The outer contour surface of the radially deformable needle wheel away from the cycloidal wheel along the axial direction is detachably connected to the inner surface of the housing.

[0006] Two roller bearings are fitted on the double eccentric sleeve of the input shaft. The cycloidal wheel is fitted on the roller bearings and is positioned between the two radially deformable pinwheels. The tooth profile of the cycloidal wheel meshes with the pin teeth on the radially deformable pinwheels. The flange assembly is fitted on the input shaft and is detachably connected to the cycloidal wheel.

[0007] The radial preload assembly is tightly fitted onto the outer contour surface of the radially deformable needle wheel and continuously applies radial preload force to it. When a wear gap appears between the needle teeth and the cycloidal wheel, the radial preload assembly drives its inner contour surface to press against the radially deformable needle wheel, causing the radially deformable needle wheel to elastically contract radially inward from the outer contour surface near the cycloidal wheel, thereby driving the needle teeth to move radially toward the cycloidal wheel to eliminate the wear gap.

[0008] This invention installs the two ends of the needle teeth between radially deformable needle wheels and fits a radial preload assembly on its outer contour surface. When a gap appears between the needle teeth and the cycloidal wheel due to wear from long-term service, the radial preload assembly continuously applies a preload force, compressing the radially deformable needle wheel to maintain a radially inward elastic compression state. This drives the needle teeth to move radially toward the tooth profile of the cycloidal wheel, achieving dynamic backlash-free meshing between the needle teeth and the cycloidal wheel. This solves the technical problem that existing cycloidal reducers experience a continuous decline in transmission accuracy due to wear after long-term use, failing to meet the requirements of high-precision applications, and improves the reducer's accuracy retention capability throughout its entire life cycle.

[0009] In a preferred embodiment, to ensure that the radially deformable needle wheel can produce stable and uniform radial contraction under the continuous pressure of the radial preload assembly, and to avoid uneven deformation caused by local stress concentration, the embodiment further includes deformation grooves distributed along the circumferential direction on the radially deformable needle wheel. The deformation grooves are opened from the end face of the radially deformable needle wheel in a direction away from the cycloidal wheel, and the number of deformation grooves is the same as the number of needle teeth.

[0010] By creating deformation grooves that are the same number as the needle teeth and evenly distributed along the circumference, the outer contour of the deformation grooves is uniformly compressed under continuous radial pressure. This guides the radially deformable needle wheel as a whole to generate synchronous elastic contraction in the radial direction, ensuring the meshing consistency between each needle tooth and the cycloidal wheel, and achieving uniform compensation for wear gaps.

[0011] In a preferred embodiment, in order to apply a continuous and symmetrical radial preload to the two sets of radially deformable pinwheels simultaneously and avoid uneven loading and stress caused by unilateral preload, the radial preload assembly includes a preload part and two sets of opposing preload sleeves that are tightly fitted onto the outer contour surfaces of the two sets of radially deformable pinwheels, with the two ends of the preload part being movably connected to the opposing surfaces of the two preload sleeves respectively.

[0012] By movably connecting the two ends of the preload to the opposite surfaces of the two preload sleeves, the continuous preload force generated by the preload can be synchronously and balancedly transmitted to the two preload sleeves, thereby driving the two sets of radially deformable pinwheels to always maintain a synchronous radial contraction state, achieving coordinated dynamic compensation for the wear gap of the pin teeth on both sides, and maintaining the force balance of the cycloidal wheel.

[0013] In a preferred embodiment, in order to achieve automatic and continuous dynamic clearance compensation after wear gaps occur between the needle teeth and the cycloidal wheel, the preload part includes a preload pin and a compression spring sleeved on the preload pin. The two ends of the preload pin are movably connected to the opposite surfaces of the two preload sleeves, and the two ends of the compression spring abut against the opposite surfaces of the two preload sleeves.

[0014] By setting the compression spring to remain in a pre-compressed energy storage state in the initial assembly state, it always applies a continuous axial thrust to the two pre-tightening sleeves. When wear gaps gradually appear, the compression of the compression spring is partially released but still remains compressed, pushing the two pre-tightening sleeves to move towards each other along the axial direction. This continuously converts the axial pre-tightening force into radial contraction force, achieving adaptive dynamic following compensation for wear gaps without manual intervention or external adjustment.

[0015] In a preferred embodiment, to ensure the smoothness and guiding accuracy of the preload sleeve during axial movement under the continuous thrust of the compression spring, and to avoid failure of preload transmission due to misalignment or jamming, corresponding preload pin holes are respectively provided on the opposite surfaces of the two preload sleeves. The two ends of the preload pin are respectively inserted into the preload pin holes of the two preload sleeves, and the compression spring drives the two preload sleeves to move towards each other along the axial direction of the preload pin holes.

[0016] By inserting both ends of the preload pin into the corresponding preload pin holes, a sliding guide structure is formed, which allows the preload sleeve to precisely displace along the axial direction of the preload pin hole under the continuous thrust of the compression spring, ensuring the uniformity of contact of the conical surface fit and the symmetry of radial contraction, thus achieving long-term stable preload.

[0017] In a preferred embodiment, in order to efficiently and controllably convert the continuous axial preload of the preload sleeve into the radial contraction force of the radially deformable needle wheel, the inner contour surface of the preload sleeve is a conical inner contour surface, and the outer contour surface of the radially deformable needle wheel that approaches the cycloidal wheel along the axial direction is a conical outer contour surface. The conical inner contour surface and the conical outer contour surface are closely fitted together, and their small ends are both facing the cycloidal wheel.

[0018] By setting the inner and outer conical contour surfaces of the small end facing the cycloidal wheel to fit together, and utilizing the wedge principle of the conical surface fit, when the preload sleeve moves away from the cycloidal wheel under the continuous axial thrust, it can accurately compress the radially deformable pin wheel through the radial component force between the conical surfaces to always maintain a radially inward contraction state, thereby achieving a linear conversion between axial displacement and radial contraction, and improving the accuracy and long-term stability of preload control.

[0019] In a preferred embodiment, in order to optimize the radial force characteristics and displacement sensitivity at different wear stages during continuous pre-tightening, the conical outer contour surface of the radially deformable pinwheel includes continuous contour lines in the axial section: a first outer conical segment AB, a first outer transition segment BC, a second outer transition segment CD, and a second outer conical segment DE; the inclination angle θ2 of the second outer conical segment DE is greater than the inclination angle θ1 of the first outer conical segment AB.

[0020] By setting two outer conical sections with different inclination angles, the first outer conical section AB with a smaller inclination angle provides a more sensitive radial displacement response in the early stage of pre-tightening, quickly compensating for small wear gaps; as wear accumulates, the pre-tightening sleeve gradually advances to the second outer conical section DE with a larger inclination angle, providing greater radial clamping force under continuous compression, ensuring that sufficient meshing stiffness can still be maintained under large clearance wear conditions, and realizing graded pre-tightening and force-position adaptation throughout the entire life cycle.

[0021] Preferably, to ensure that the pre-tightening sleeve and the radially deformable pinwheel maintain an ideal contact state during each stage of continuous pre-tightening, and to avoid stress concentration caused by point or line contact due to mismatched slopes, the tapered inner contour surface of the pre-tightening sleeve includes continuous contour lines in the axial section: a first inner tapered segment A'B', a first inner transition segment B'C', a second inner transition segment C'D', and a second inner tapered segment D'E'; the first inner tapered segment A'B' has the same slope as the first outer tapered segment AB, and the second inner tapered segment D'E has the same slope as the second outer tapered segment DE.

[0022] By setting the first inner cone segment A'B' and the first outer cone segment AB, and the second inner cone segment D'E' and the second outer cone segment DE to the same slope, the inner and outer cone surfaces form surface contact in each corresponding contact area, ensuring a uniform distribution of continuous radial pressure, improving pre-tightening stability and contact stiffness, and avoiding local wear or excessive stress.

[0023] In a preferred embodiment, in order to precisely control the limit working position of radial preload and prevent excessive continuous preload from causing structural damage or jamming, the first outer transition section BC and the second outer transition section CD are perpendicular to each other in the axial section, and the first inner transition section B'C' and the second inner transition section C'D' are perpendicular to each other.

[0024] By setting the transition surfaces to be perpendicular to each other, the second inner cone segment D'E' and the second outer cone segment DE are in continuous contact until the second outer transition segment CD and the first inner transition segment B'C' are collinear, reaching the limit position of radial preload. This achieves reliable control and protection of the preload stroke, ensuring that the reducer can still operate safely under extreme wear conditions.

[0025] In a preferred embodiment, to facilitate the assembly process of the reducer and the reliability of power transmission, the flange assembly includes an input end flange, a connecting end flange, and an output end flange sleeved on the input shaft. The input end flange and the connecting end flange are respectively disposed on both sides of the cycloidal wheel and are detachably connected to the cycloidal wheel. The output end flange is connected to the connecting end flange.

[0026] By setting the flange assembly as a multi-segment modular structure, the input flange and the connecting flange are detachably connected to both sides of the cycloidal wheel, which facilitates the installation, positioning, replacement and maintenance of the cycloidal wheel. At the same time, the output flange is connected to the connecting flange to form a complete power output path, achieving the beneficial effects of compact structure, convenient disassembly and assembly, and stable transmission.

[0027] Beneficial effects: This invention installs the two ends of the pin teeth between radially deformable pin wheels and fits a radial preload assembly that continuously applies preload on its outer contour surface. When gaps appear between the pin teeth and the cycloidal wheel due to long-term service wear, the radial preload assembly automatically drives the radially deformable pin wheels to produce elastic radial contraction, causing the pin teeth to move radially towards the cycloidal wheel, achieving adaptive dynamic compensation for wear gaps and improving the transmission accuracy maintenance capability of the reducer throughout its entire life cycle. By opening deformation grooves with the same number as the pin teeth, the radially deformable pin wheels are guided to produce uniform and synchronous radial contraction, improving the meshing consistency between each pin tooth and the cycloidal wheel. By adopting a conical surface mating structure, the axial preload is efficiently converted into radial contraction force, and a multi-segment tapered surface is set to achieve graded preload. At the same time, the sliding guide structure of the preload pin and the preload pin hole ensures the smoothness of the axial movement of the preload sleeve. The vertical design of the transition surface achieves precise control of the preload limit position. This effectively solves the technical problem of transmission accuracy decline due to wear after long-term use of existing cycloidal reducers, and can meet the requirements of high-precision applications such as humanoid robots for long-term stable operation of reducers. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0029] Figure 1 This is a cross-sectional view of the speed reducer of the present invention;

[0030] Figure 2 This is an exploded view of the speed reducer of the present invention;

[0031] Figure 3 This is an assembly diagram of the radial preload assembly and the radially deformable pinwheel of the present invention;

[0032] Figure 4 This is a structural diagram of the radially deformable pinwheel of the present invention;

[0033] Figure 5 This is a structural diagram of the pre-tightening sleeve of the present invention;

[0034] Figure 6This is a structural diagram of the input shaft with double eccentric sleeves according to the present invention;

[0035] Figure 7 This is a structural diagram of the cycloidal wheel of the present invention;

[0036] Figure 8 This is a structural diagram of the inner and outer contours of the present invention;

[0037] Figure 9 This is a diagram showing the working state of the inner and outer contours of the present invention. Detailed Implementation

[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0040] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0041] like Figures 1-7 As shown, a robot joint radial preload cycloidal reducer includes a housing 1 and a flange assembly 2 installed in the housing 1, an input shaft 3 with a double eccentric sleeve, a cycloidal wheel 4, a pin tooth 5, a radially deformable pin wheel 6, and a radial preload assembly 7.

[0042] Two sets of radially deformable needle wheels 6 are arranged opposite each other along the axial direction. The two ends of the needle teeth 5 are respectively connected to the opposite surfaces of the two radially deformable needle wheels 6. The outer contour surface of the radially deformable needle wheels 6 away from the cycloidal wheel 4 along the axial direction is detachably connected to the inner surface of the housing 1.

[0043] Two roller bearings 8 are fitted on the double eccentric sleeve of the input shaft 3. The cycloidal wheel 4 is fitted on the roller bearings 8 and is located between the two radially deformable pinwheels 6. The tooth profile of the cycloidal wheel 4 meshes with the pin teeth 5 on the radially deformable pinwheel 6. The flange assembly 2 is fitted on the input shaft 3 and is detachably connected to the cycloidal wheel 4.

[0044] The radial preload assembly 7 is tightly fitted onto the outer contour surface of the radially deformable needle wheel 6 and continuously applies radial preload force to it. When a wear gap appears between the needle tooth 5 and the cycloidal wheel 4, the radial preload assembly 7 drives its inner contour surface to press the radially deformable needle wheel 6, causing the radially deformable needle wheel 6 to elastically contract radially inward from the outer contour surface of the cycloidal wheel 4, thereby driving the needle tooth 5 to move radially toward the cycloidal wheel 4 to eliminate the wear gap.

[0045] By mounting the two ends of the needle tooth 5 between the radially deformable needle wheel 6 and fitting the radial preload assembly 7 on its outer contour surface, when the needle tooth 5 and the cycloidal wheel 4 develop a gap due to long-term service wear, the radial preload assembly 7 continuously applies a preload force, compressing the radially deformable needle wheel 6 to always maintain a radially inward contraction elastic compression state, thereby driving the needle tooth 5 to move radially towards the tooth profile direction of the cycloidal wheel 4, realizing dynamic backlash-free meshing between the needle tooth 5 and the cycloidal wheel 4. This solves the technical problem that the transmission accuracy of existing cycloidal reducers continuously decreases due to wear after long-term use, and cannot meet the requirements of high-precision applications, thus improving the accuracy retention capability of the reducer throughout its entire life cycle.

[0046] In this embodiment, the radially deformable pinwheel 6 refers to a pinwheel structure made of elastic materials such as alloy steel, which can produce elastic radial contraction under the continuous action of the radial preload assembly 7. Its deformation is within the elastic range and can restore its initial shape after unloading.

[0047] To ensure that the radially deformable pinwheel 6 can produce stable and uniform radial contraction under the continuous pressure of the radial preload assembly 7, and to avoid uneven deformation caused by local stress concentration, deformation grooves 61 are distributed along the circumference on the radially deformable pinwheel 6. The deformation grooves 61 are opened from the end face of the radially deformable pinwheel 6 in a direction away from the cycloidal wheel 4. The number of deformation grooves 61 is the same as that of the pin teeth 5.

[0048] By opening deformation grooves 61 with the same number as the needle teeth 5 and evenly distributed along the circumference, the outer contour of the deformation grooves 61 is uniformly compressed under continuous radial pressure, thereby guiding the radially deformable needle wheel 6 to generate synchronous elastic contraction in the radial direction, ensuring the meshing consistency between each needle tooth 5 and the cycloidal wheel 4, and achieving uniform compensation of wear gap.

[0049] In order to apply a continuous and symmetrical radial preload to the two sets of radially deformable pinwheels 6 at the same time, and to avoid uneven load and force caused by unilateral preload, the radial preload assembly 7 includes a preload part 71 and two sets of opposing preload sleeves 72 that are tightly fitted on the outer contour surfaces of the two sets of radially deformable pinwheels 6 respectively. The two ends of the preload part 71 are movably connected to the opposing surfaces of the two preload sleeves 72 respectively.

[0050] By movably connecting the two ends of the preload 71 to the opposite surfaces of the two preload sleeves 72, the continuous preload force generated by the preload 71 can be synchronously and balancedly transmitted to the two preload sleeves 72, thereby driving the two sets of radially deformable pin wheels 6 to always maintain a synchronous radial contraction state, realizing coordinated dynamic compensation for the wear gap of the pin teeth 5 on both sides, and maintaining the force balance of the cycloidal wheel 4.

[0051] In order to achieve automatic and continuous dynamic gap compensation after wear gaps occur between the needle tooth 5 and the cycloidal wheel 4, the preload part 71 includes a preload pin 711 and a compression spring 712 sleeved on the preload pin 711. The two ends of the preload pin 711 are movably connected to the opposite surfaces of the two preload sleeves 72, and the two ends of the compression spring 712 abut against the opposite surfaces of the two preload sleeves 72.

[0052] By setting the compression spring 712 to remain in a pre-compressed energy storage state in the initial assembly state, it always applies a continuous axial thrust to the two pre-tightening sleeves 72. When wear gaps gradually appear, the compression of the compression spring 712 is partially released but still remains compressed, pushing the two pre-tightening sleeves 72 to move towards each other axially, thereby continuously converting the axial pre-tightening force into radial contraction force, realizing adaptive dynamic following compensation for wear gaps without manual intervention or external adjustment.

[0053] To ensure the smoothness and guiding accuracy of the preload sleeve 72 when it moves axially under the continuous thrust of the compression spring 712, and to avoid failure of preload transmission due to misalignment or jamming, corresponding preload pin holes 721 are respectively opened on the opposite surfaces of the two preload sleeves 72. The two ends of the preload pin 711 are respectively inserted into the preload pin holes 721 of the two preload sleeves 72, and the compression spring 712 drives the two preload sleeves 72 to move towards each other along the axial direction of the preload pin holes 721.

[0054] By inserting both ends of the preload pin 711 into the corresponding preload pin holes 721, a sliding guide structure is formed, so that under the continuous thrust of the compression spring 712, the preload sleeve 72 can be precisely displaced along the axial direction of the preload pin hole 721, ensuring the uniformity of contact of the conical surface fit and the symmetry of radial contraction, and achieving long-term stable preload.

[0055] In order to efficiently and controllably convert the continuous axial preload of the preload sleeve 72 into the radial contraction force of the radially deformable pinwheel 6, the inner contour surface of the preload sleeve 72 is a conical inner contour surface, and the outer contour surface of the radially deformable pinwheel 6 that approaches the cycloidal wheel 4 along the axial direction is a conical outer contour surface. The conical inner contour surface and the conical outer contour surface are closely fitted, and their small ends are both facing the cycloidal wheel 4.

[0056] By setting the conical inner and outer contour surfaces of the small end facing the cycloidal wheel 4 to fit together, and utilizing the wedge principle of the conical surface fit, when the preload sleeve 72 moves away from the cycloidal wheel 4 under continuous axial thrust, it can accurately compress the radially deformable pin wheel 6 to always maintain a radially inward contraction state through the radial component force between the conical surfaces, thereby realizing the linear conversion between axial displacement and radial contraction and improving the accuracy and long-term stability of preload control.

[0057] In order to optimize the radial force characteristics and displacement sensitivity at different wear stages during continuous pre-tightening, the conical outer contour surface of the radially deformable pinwheel 6 includes continuous contour lines in the axial section: first outer conical segment AB, first outer transition segment BC, second outer transition segment CD, and second outer conical segment DE; the tilt angle θ2 of the second outer conical segment DE is greater than the tilt angle θ1 of the first outer conical segment AB.

[0058] By setting two outer cone sections with different inclination angles, the first outer cone section AB with a smaller inclination angle provides a more sensitive radial displacement response in the early stage of pre-tightening, quickly compensating for small wear gaps; as wear accumulates, the pre-tightening sleeve 72 gradually advances to the second outer cone section DE with a larger inclination angle, providing greater radial clamping force under continuous compression, ensuring that sufficient meshing stiffness can still be maintained under large clearance wear conditions, and realizing graded pre-tightening and force-position adaptation throughout the entire life cycle.

[0059] To ensure that the pre-tightening sleeve 72 and the radially deformable pinwheel 6 maintain an ideal contact state during each stage of continuous pre-tightening, and to avoid stress concentration caused by point or line contact due to mismatched slopes, the tapered inner contour surface of the pre-tightening sleeve 72 includes continuous contour lines in the axial section: a first inner tapered segment A'B', a first inner transition segment B'C', a second inner transition segment C'D', and a second inner tapered segment D'E'; the first inner tapered segment A'B' has the same slope as the first outer tapered segment AB, and the second inner tapered segment D'E has the same slope as the second outer tapered segment DE.

[0060] By setting the first inner cone segment A'B' and the first outer cone segment AB, and the second inner cone segment D'E' and the second outer cone segment DE to the same slope, the inner and outer cone surfaces form surface contact in each corresponding contact area, ensuring a uniform distribution of continuous radial pressure, improving pre-tightening stability and contact stiffness, and avoiding local wear or excessive stress.

[0061] In order to precisely control the limit working position of radial preload and prevent excessive and continuous preload from causing structural damage or jamming, in the axial section, the first outer transition section BC and the second outer transition section CD are perpendicular to each other, and the first inner transition section B'C' and the second inner transition section C'D' are perpendicular to each other.

[0062] By setting the transition sections to be perpendicular to each other, the second inner cone section D'E' and the second outer cone section DE continue to contact each other until the second outer transition section CD and the first inner transition section B'C' are collinear, reaching the limit position of radial preload. This achieves reliable control and protection of the preload stroke, ensuring that the reducer can still operate safely under extreme wear conditions.

[0063] like Figure 8 As shown, to ensure the effectiveness of radial preload under different wear conditions, in the axial section, both the inner contour surface of the preload sleeve 72 and the outer contour surface of the radially deformable pinwheel 6 are represented by continuous piecewise functions, establishing a rectangular coordinate system XOY:

[0064] (1) The first outer cone segment AB of the outer contour has the following function expression:

[0065]

[0066] In the formula, , For any point on the first outer cone segment AB of the outer contour, The horizontal and vertical coordinates in the coordinate system are: θ1 is the inclination angle of the first outer cone segment AB of the outer contour, f is the small end radius of the first outer cone segment AB of the outer contour, and g is the width of the first outer cone segment AB of the outer contour.

[0067] (2) The first outer transition segment BC of the outer contour has the following function expression:

[0068]

[0069] In the formula, , For any point on the first outer transition segment BC of the outer contour, The horizontal and vertical coordinates in the coordinate system, where h is the width of the first outer transition segment BC of the outer contour.

[0070] (3) The function expression of the second outer transition segment CD of the outer contour is:

[0071]

[0072] In the formula, , For any point on the first outer cone segment CD, The horizontal and vertical coordinates in the coordinate system, where m is the height of the second outer transition segment CD of the outer contour.

[0073] (4) The function expression for the second outer cone segment DE of the outer contour is:

[0074]

[0075] In the formula, , For any point on the second outer cone segment DE of the outer contour, The x and y coordinates in the coordinate system, k is the width of the second outer cone segment DE of the outer contour. θ2 is the inclination angle of the second outer cone segment DE of the outer contour.

[0076] (5) The first inner cone segment A'B' of the inner contour has the following function expression:

[0077]

[0078] In the formula, , For any point on the first inner cone segment A'B' of the inner contour, The horizontal and vertical coordinates in the coordinate system.

[0079] (6) The first inner transition segment B'C' of the inner contour has the following function expression:

[0080]

[0081] In the formula, , For any point on the first inner transition segment B'C' of the inner contour, The horizontal and vertical coordinates in the coordinate system.

[0082] (7) The function expression of the second inner transition segment C'D' of the inner contour is:

[0083]

[0084] In the formula, , For any point on the second inner transition segment C'D' of the inner contour, The horizontal and vertical coordinates in the coordinate system.

[0085] (8) The function expression for the second inner cone segment D'E' of the inner contour is:

[0086]

[0087] In the formula, , , where are the x and y coordinates of any point on the second inner cone segment D'E' of the inner contour in the XOY coordinate system, and n is the width of the second inner cone segment D'E' of the inner contour.

[0088] like Figure 9 As shown, the motion process of the inner and outer contours under working conditions, represented by a continuous piecewise function, consists of the following five stages.

[0089] The initial stage is as shown in Figure 9(a). The first outer cone segment AB of the outer contour and the first inner cone segment A'B' of the inner contour completely coincide, and at this time, the radially deformable pinwheel 6 has no radial displacement.

[0090] The second stage is shown in Figure 9(b). When a wear gap appears between the cycloidal wheel 4 and the needle tooth 5, the preload sleeve 72 moves axially, and the radially deformable needle wheel 6 undergoes radial displacement.

[0091] The third stage is shown in Figure 9(c). When the wear gap increases, point Aʹ of the first inner cone segment A'B' of the inner contour coincides with point B of the first outer cone segment AB of the outer contour, and point D coincides with point Dʹ.

[0092] The fourth stage is shown in Figure 9(d). As the wear gap continues to increase, the second inner cone segment D'E' of the inner contour and the second outer cone segment DE of the outer contour come into collinear contact, pushing the radially deformable pin wheel 6 to move radially, and the amount of displacement continues to increase.

[0093] The fifth stage is shown in Figure 9(e). When the first inner transition segment B'C' of the inner contour is collinear with the second outer transition segment CD of the outer contour, the radial pre-tightening limit position is reached, forming a physical limit.

[0094] In this invention, θ2 is greater than θ1. When the preload sleeve 72 moves axially by the same distance, the radial displacement of the second outer cone segment DE of the outer contour is greater than that of the first outer cone segment AB of the outer contour. This ensures that radial preload can be performed more effectively after the wear of the cycloidal wheel 4 and the needle tooth 5 develops from the stable wear period to the severe wear period. At the same time, by characterizing the inner and outer contours through continuous piecewise functions, the continuity and accuracy of the five stages during the motion process can be guaranteed.

[0095] To facilitate the assembly process of the reducer and ensure the reliability of power transmission, the flange assembly 2 includes an input end flange 21, a connecting end flange 22, and an output end flange 23 sleeved on the input shaft 3. The input end flange 21 and the connecting end flange 22 are respectively disposed on both sides of the cycloidal wheel 4 and are detachably connected to the cycloidal wheel 4. The output end flange 23 is connected to the connecting end flange 22.

[0096] By setting the flange assembly 2 as a multi-segment modular structure, the input flange 21 and the connecting flange 22 are detachably connected to both sides of the cycloidal wheel 4, which facilitates the installation, positioning, replacement and maintenance of the cycloidal wheel 4. At the same time, the output flange 23 is connected to the connecting flange 22 to form a complete power output path, achieving the beneficial effects of compact structure, convenient disassembly and assembly, and stable transmission.

[0097] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0098] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A cycloidal reducer with radial preload on a robot joint, characterized in that: Includes housing (1) and flange assembly (2) installed in housing (1), input shaft (3) with double eccentric sleeve, cycloidal wheel (4), pin tooth (5), radially deformable pin wheel (6), and radial preload assembly (7). Two sets of radially deformable pinwheels (6) are arranged opposite each other along the axial direction. The two ends of the pin teeth (5) are respectively connected to the opposite surfaces of the two radially deformable pinwheels (6). The outer contour surface of the radially deformable pinwheels (6) away from the cycloidal wheel (4) along the axial direction is detachably connected to the inner side of the housing (1). Two roller bearings (8) are fitted on the double eccentric sleeve of the input shaft (3). The cycloidal wheel (4) is fitted on the roller bearings (8) and is located between the two radially deformable pinwheels (6). The tooth profile of the cycloidal wheel (4) meshes with the pin teeth (5) on the radially deformable pinwheels (6). The flange assembly (2) is fitted on the input shaft (3) and is detachably connected to the cycloidal wheel (4). The radial preload assembly (7) is tightly fitted onto the outer contour surface of the radially deformable pinwheel (6) and continuously applies radial preload force to it. When a wear gap appears between the pin tooth (5) and the cycloidal wheel (4), the radial preload assembly (7) drives its inner contour surface to press the radially deformable pinwheel (6), causing the radially deformable pinwheel (6) to elastically contract radially inward along the outer contour surface of the cycloidal wheel (4), thereby driving the pin tooth (5) to move radially toward the cycloidal wheel (4) to eliminate the wear gap.

2. The robot joint radial preload cycloidal reducer according to claim 1, characterized in that: It also includes deformation grooves (61) distributed along the circumference on the radially deformable pinwheel (6), the deformation grooves (61) being opened from the end face of the radially deformable pinwheel (6) in a direction away from the cycloidal wheel (4), and the number of deformation grooves (61) being the same as the number of pin teeth (5).

3. The robot joint radial preload cycloidal reducer according to claim 1 or 2, characterized in that: The radial preload assembly (7) includes a preload part (71) and two sets of opposing preload sleeves (72) that are tightly fitted onto the outer contour surfaces of two sets of radially deformable pinwheels (6). The two ends of the preload part (71) are movably connected to the opposing surfaces of the two preload sleeves (72).

4. The robot joint radial preload cycloidal reducer according to claim 3, characterized in that: The pre-tightening part (71) includes a pre-tightening pin (711) and a compression spring (712) sleeved on the pre-tightening pin (711). The two ends of the pre-tightening pin (711) are movably connected to the opposite surfaces of the two pre-tightening sleeves (72), and the two ends of the compression spring (712) abut against the opposite surfaces of the two pre-tightening sleeves (72).

5. The robot joint radial preload cycloidal reducer according to claim 4, characterized in that: The two pre-tightening sleeves (72) have corresponding pre-tightening pin holes (721) on their opposite surfaces. The two ends of the pre-tightening pin (711) are inserted into the pre-tightening pin holes (721) of the two pre-tightening sleeves (72). The compression spring (712) drives the two pre-tightening sleeves (72) to move towards each other along the axial direction of the pre-tightening pin holes (721).

6. The robot joint radial preload cycloidal reducer according to claim 3, characterized in that: The inner contour surface of the pre-tightening sleeve (72) is a conical inner contour surface, and the outer contour surface of the radially deformable pinwheel (6) that approaches the cycloidal wheel (4) along the axial direction is a conical outer contour surface. The conical inner contour surface and the conical outer contour surface are closely fitted, and their small ends are both facing the cycloidal wheel (4).

7. The robot joint radial preload cycloidal reducer according to claim 6, characterized in that: The radially deformable pinwheel (6) has a tapered outer profile surface that includes a continuous profile line in the axial section: a first outer cone segment AB, a first outer transition segment BC, a second outer transition segment CD, and a second outer cone segment DE; the tilt angle θ2 of the second outer cone segment DE is greater than the tilt angle θ1 of the first outer cone segment AB.

8. The robot joint radial preload cycloidal reducer according to claim 7, characterized in that: The tapered inner profile of the pre-tightening sleeve (72) includes a continuous profile in the axial section: a first inner tapered segment A'B', a first inner transition segment B'C', a second inner transition segment C'D', and a second inner tapered segment D'E'; the first inner tapered segment A'B' has the same slope as the first outer tapered segment AB, and the second inner tapered segment D'E has the same slope as the second outer tapered segment DE.

9. The robot joint radial preload cycloidal reducer according to claim 8, characterized in that: In the axial section, the first outer transition segment BC and the second outer transition segment CD are perpendicular to each other, and the first inner transition segment B'C' and the second inner transition segment C'D' are perpendicular to each other.

10. The robot joint radial preload cycloidal reducer according to claim 1, characterized in that: The flange assembly (2) includes an input end flange (21), a connecting end flange (22), and an output end flange (23) sleeved on the input shaft (3). The input end flange (21) and the connecting end flange (22) are respectively disposed on both sides of the cycloidal wheel (4) and are detachably connected to the cycloidal wheel (4). The output end flange (23) is connected to the connecting end flange (22).

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