Flexspline and harmonic reducer

Abstract

The present invention provides a flexible wheel and a harmonic reducer. The flexible wheel comprises a gear ring (301), a cylinder (302) and a cylinder bottom (304). The gear ring (301) is arranged on the outer peripheral wall of the cylinder (302), and the cylinder bottom (304) is connected to the bottom of the cylinder (302). The flexible wheel satisfies: wherein T is the load capacity parameter of the flexible wheel, δ is the wall thickness of the gear ring, H is the hardness of the flexible wheel material, and d m is the neutral circle diameter of the flexspline, w0 is the radial deformation of the flexspline, K R is the flexspline strength coefficient, k H is the material hardness coefficient, and s is the thickness of the cylinder at the flexspline gear ring. According to the flexspline of the present invention, the tensile strength of the flexspline can be enhanced, and the load-bearing capacity and transmission performance of the flexspline can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of speed reducers, and in particular to a flexible spline speed reducer. Background Art

[0002] Harmonic reducers are precision transmission devices widely used in the joint modules of industrial robots. Developed based on the principle of wave deformation, they typically consist of three main components: a flexspline, a rigid spline, and a wave generator. The flexspline is an elastic component that undergoes periodic elastic deformation under the action of the wave generator. This deformation causes the flexspline teeth to mesh with the rigid spline teeth, thereby achieving motion and torque transmission. In harmonic drive, the meshing of the rigid spline teeth with the flexspline teeth reduces speed and increases torque.

[0003] The flexspline is one of the three core components of a harmonic reducer. Its structure directly impacts the transmission's load capacity, lifespan, meshing performance, and processability. During design, axial tooth deflection caused by radial deformation must be minimized or eliminated to ensure good tooth contact and reduce cylinder wall stress.

[0004] The wall thickness and hardness of the flexspline affect the force and concentrated stress generated by the axial deflection of the flexspline during operation, as well as the stress deformation caused by the meshing of the flexspline teeth and the rigid wheel teeth, affecting the tensile strength of the flexspline, thereby affecting the transmission performance and service life of the harmonic reducer.

[0005] Regarding the structural design of the flexible wheel, the related art proposes a cup-type flexible wheel with a gradually changing wall thickness and a harmonic gear transmission device. The gradually changing flexible wheel wall thickness is adopted. This structure cannot change the stress deformation and concentrated stress distribution, and therefore cannot fundamentally improve the flexible wheel's load-bearing capacity and transmission performance. Summary of the Invention

[0006] The main purpose of the present invention is to provide a flexible pulley that can enhance the tensile strength of the flexible pulley and improve the load-bearing capacity and transmission performance of the flexible pulley.

[0007] To achieve the above object, according to one aspect of the present invention, a flexible spline is provided, comprising a gear ring, a cylinder and a cylinder bottom, wherein the gear ring is arranged on the outer peripheral wall of the cylinder, and the cylinder bottom is connected to the bottom of the cylinder, and the flexible spline meets the following requirements:

[0008]

[0009] Where T is the load capacity parameter of the flexspline, δ is the wall thickness of the gear ring, H is the hardness of the flexspline material, d m is the neutral circle diameter of the flexspline, w0 is the radial deformation of the flexspline, K R is the flexspline strength coefficient, k H is the material hardness coefficient, and s is the cylinder thickness at the flexspline gear ring.

[0010] Furthermore, K R Satisfies: 1.24≤K R ≤1.37.

[0011] Furthermore, k H Satisfies: 0.28≤k H ≤0.87.

[0012] Furthermore, Where σ is the tensile strength of the flexspline.

[0013] Furthermore, the cylinder body includes a cylinder wall and a bottom corner, the cylinder bottom includes a flange and a diaphragm, the diaphragm is located on the inner circumference side of the flange and connected to the inner wall of the flange, and the bottom corner is connected between the cylinder wall and the diaphragm.

[0014] Furthermore, the cylinder is a smooth cylinder.

[0015] Furthermore, the gear ring is arranged at the outer edge end of the cylinder.

[0016] Furthermore, a transition connection section is provided on one side of the gear ring close to the bottom of the cylinder, the thickness of the transition connection section decreases gradually in the direction away from the gear ring, and the end of the gear ring is connected to the outer wall of the cylinder through the transition connection section.

[0017] According to another aspect of the present invention, a harmonic reducer is provided, comprising a flexspline and a rigid spline, wherein the flexspline and the rigid spline are meshed for transmission, and the flexspline is the above-mentioned flexspline.

[0018] Furthermore, the harmonic reducer also includes a bearing and a wave generator. The rigid wheel cooperates with the first end of the bearing, the flexible wheel cooperates with the second end of the bearing, and the wave generator is sleeved on the inner hole of the flexible wheel.

[0019] Applying the technical solution of the present invention, the flexible spline includes a gear ring, a cylinder and a cylinder bottom. The gear ring is arranged on the outer peripheral wall of the cylinder, and the cylinder bottom is connected to the bottom of the cylinder. The flexible spline meets the following requirements:

[0020]

[0021] Where T is the load capacity parameter of the flexspline, δ is the wall thickness of the gear ring, H is the hardness of the flexspline material, d m is the neutral circle diameter of the flexspline, w0 is the radial deformation of the flexspline, K R is the flexspline strength coefficient, k H is the material hardness coefficient, and s is the cylinder thickness at the flexspline gear ring. The above formula can be used to correlate the design wall thickness of the flexspline with the material hardness. When designing the tensile strength of the flexspline, the design wall thickness and material hardness can be comprehensively considered, resulting in a better overall performance of the flexspline's wall thickness and material hardness, thereby enhancing the flexspline's tensile strength, carrying capacity, and transmission performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0023] Figure 1 A schematic structural diagram of a flexible pulley according to an embodiment of the present invention is shown;

[0024] Figure 2 A diagram showing the dimensions and structure of a flexible pulley according to an embodiment of the present invention; and

[0025] Figure 3 The figure shows a schematic structural diagram of a harmonic reducer according to an embodiment of the present invention.

[0026] The above drawings include the following reference numerals:

[0027] 1. Rigid wheel; 2. Bearing; 3. Flexspline; 4. Wave generator; 5. Fastening screw; 301. Ring gear; 302. Cylinder; 303. Transition connecting section; 304. Cylinder bottom; 3021. Cylinder wall; 3022. Bottom corner; 3041. Flange; 3042. Diaphragm. DETAILED DESCRIPTION

[0028] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0029] See also Figures 1 to 3 As shown, according to an embodiment of the present invention, the flexible spline includes a gear ring 301, a cylinder 302 and a cylinder bottom 304. The gear ring 301 is arranged on the outer peripheral wall of the cylinder 302, and the cylinder bottom 304 is connected to the bottom of the cylinder 302. The flexible spline meets the following requirements:

[0030]

[0031] Where T is the load capacity parameter of the flexspline, δ is the wall thickness of the gear ring, H is the hardness of the flexspline material, d m is the neutral circle diameter of the flexspline, w0 is the radial deformation of the flexspline, K R is the flexspline strength coefficient, k H is the material hardness coefficient, and s is the cylinder thickness at the flexspline gear ring.

[0032] During the operation of the harmonic reducer, the tensile strength of the flexspline decreases due to the stress deformation caused by axial deflection and gear pair meshing, resulting in a decrease in the flexspline's load-bearing capacity and transmission performance.

[0033] In this embodiment, when designing the flexspline, the design wall thickness of the flexspline can be correlated with the material hardness of the flexspline through the above formula. In this way, when designing the tensile strength of the flexspline, the design wall thickness and material hardness can be comprehensively considered, so that the comprehensive performance of the wall thickness and material hardness of the flexspline is better, thereby enhancing the tensile strength of the flexspline and improving the load-bearing capacity and transmission performance of the flexspline.

[0034] By optimizing the design of wall thickness and material hardness, the flexible wheel structure can be optimized, the tooth transmission efficiency can be improved, the meshing process of the rigid-flex wheel gear can be ensured, the meshing between the teeth is more sufficient, the gear transmission accuracy can be maintained for a longer period of time, and thus the overall performance of the harmonic reducer can be improved.

[0035] In addition, it can also increase the tensile strength of the flexible wheel, greatly reduce the stress deformation of the flexible wheel, enhance the impact resistance and wear resistance of the flexible wheel teeth, ensure that the flexible wheel has good movement performance, extend its service life, and ultimately increase the service life of the harmonic reducer as a whole.

[0036] In one embodiment, K R Satisfies: 1.24≤K R ≤1.37.

[0037] In one embodiment, k H Satisfies: 0.28≤k H ≤0.87.

[0038] Under the constraint K R 、k H The greater the load capacity parameter T, the greater the tensile strength of the flexspline, and the stress deformation of the flexspline will be greatly reduced. Therefore, this type of structure has a high tensile strength of the flexspline and a small stress deformation. During the movement, the rigid-flex spline teeth are fully engaged, reducing the impact and wear between the teeth, thereby improving the flexspline movement performance and service life, and ultimately achieving the improvement of the performance and life of the harmonic reducer.

[0039] In one embodiment, Where σ is the tensile strength of the flexspline.

[0040] Based on the theoretical calculation and analysis of cylindrical shell, the load-bearing capacity of the flexspline depends on the tensile strength, that is, the circumferential stress; the structural dimensions of the flexspline, such as the radial deformation w0 and the neutral circle diameter d m Affects the circumferential stress of the flexible pulley, in which the circumferential stress of the flexible pulley is proportional to the radial deformation w0, and the circumferential stress of the flexible pulley is proportional to (d m / 2) 2 Inversely proportional; the tensile strength of the material satisfies the strength-hardness conversion formula: In determining the radial deformation w0 of the flexible wheel and the neutral circle diameter d mIn this case, the wall thickness and hardness can be linked to express a load capacity parameter T, and the load capacity parameter T is used to characterize the strength value of the flexible wheel.

[0041] In the formula, T is used to represent the strength value of the flexible wheel. According to the above formula, the relationship between the strength value T and the wall thickness and hardness value can be obtained. When any one of them is determined, the curve form of the strength value T associated with the other parameter is close to an arch and has a maximum value.

[0042] In the related art, the wall thickness value and the hardness value are designed separately. In the embodiment of the present invention, one of the wall thickness or hardness value (for example, the wall thickness) is substituted into the formula together with other parameters to find the other parameter (for example, the hardness) that makes T reach the maximum value, so that the design of the flexible wheel can obtain the maximum load-bearing capacity, improve the load-bearing capacity and transmission performance of the flexible wheel, and extend the service life of the flexible wheel.

[0043] In one embodiment, the cylinder body 302 includes a cylinder wall 3021 and a bottom corner 3022, and the cylinder bottom 304 includes a flange 3041 and a diaphragm 3042, the diaphragm 3042 is located on the inner circumference side of the flange 3041 and is connected to the inner wall of the flange 3041, and the bottom corner 3022 is connected between the cylinder wall 3021 and the diaphragm 3042.

[0044] In this embodiment, the bottom corner 3022 is an arc structure, which can form an arc transition connection at the connection position between the cylinder 302 and the cylinder bottom 304, which has better connection performance, can reduce connection stress, and can reduce molding difficulty.

[0045] In one embodiment, the cylinder 302 is a smooth cylinder.

[0046] In one embodiment, the ring gear 301 is arranged at the outer edge of the cylinder 302, that is, the ring gear 301 is arranged at the end of the cylinder 302 away from the cylinder bottom 304. This structural arrangement can prevent the engagement of the ring gear 301 and the rigid wheel 1 from being excessively affected by the structure of the cylinder bottom 304, thereby improving the meshing transmission performance of the flexible wheel and the rigid wheel 1 and making it easier to ensure the design performance.

[0047] In one embodiment, a transition section 303 is provided on the side of the gear ring 301 close to the cylinder bottom 304. The thickness of the transition section 303 decreases in the direction away from the gear ring 301. The end of the gear ring 301 is connected to the outer wall of the cylinder 302 through the transition section 303.

[0048] In this embodiment, the end of the ring gear 301 near the cylinder bottom 304 is connected to the cylinder body 302 via a transition section 303. Since the meshing of the flexspline and the rigid pulley 1 is mainly achieved through the ring gear 301, the ring gear 301 is the main load-bearing component in the meshing of the flexspline and the rigid pulley 1 and needs to withstand a large force. To ensure the service life of the flexspline, it is necessary to ensure the connection strength between the ring gear 301 and the cylinder body 302. By adding the transition section 303 to the end of the ring gear 301, the inner wall of the ring gear 301 is fixedly connected to the outer wall of the cylinder body 302. The end face of the ring gear 301 is connected to the cylinder body 302 via the transition section 303. This can improve the connection strength between the ring gear 301 and the cylinder body 302, improve the overall structural strength of the flexspline structure, and increase the force that the ring gear 301 can withstand when meshing with the rigid pulley 1, thereby enhancing the overall structural performance of the flexspline.

[0049] The thickness of the transition section 303 decreases as it moves away from the ring gear 301. This allows the transition section 303 to become thinner as it approaches the cylinder bottom 304. This reduces the impact of the connection structure between the cylinder bottom 304 and the cylinder body 302, and reduces the impact on the deformation of the cylinder body 302 at the location of the ring gear 301 during meshing with the rigid wheel 1. This improves the meshing between the flexspline and the rigid wheel 1 and enhances the matching performance between the flexspline and the rigid wheel 1. The thickness of the transition section 303 refers to the thickness along the radial direction of the cylinder body 302.

[0050] The transition connecting section 303 may adopt a concave arc structure.

[0051] The cylinder 302 may be designed with a constant wall thickness or a variable wall thickness.

[0052] The flexible pulley 3 can be a top-hat type flexible pulley, a cup type flexible pulley or a short cylinder type flexible pulley.

[0053] See also Figure 1 As shown, according to an embodiment of the present invention, the harmonic reducer includes a flexspline 3 and a rigid wheel 1, the flexspline 3 and the rigid wheel 1 are meshed for transmission, and the flexspline 3 is the above-mentioned flexspline.

[0054] In one embodiment, the harmonic reducer further includes a bearing 2 and a wave generator 4 , the rigid wheel 1 cooperates with the first end of the bearing 2 , the flex spline 3 cooperates with the second end of the bearing 2 , and the wave generator 4 is sleeved on the inner hole of the flex spline 3 .

[0055] The rigid wheel 1 cooperates with the left end of the bearing 2, and the flexible wheel 3 cooperates with the right end of the bearing 2; there are four evenly distributed through holes on the end face of the rigid wheel 1, and the fastening screws 5 pass through the four evenly distributed through holes to the threaded holes of the bearing 2 to fasten the rigid wheel 1 and the bearing 2; there are four evenly distributed through holes on the bottom end face of the flexible wheel 3, and the fastening screws 5 pass through the four through holes to the threaded holes of the bearing 2 to fasten the flexible wheel 3 and the bearing 2; the wave generator 4 consists of a boss with an elliptical profile and a flexible bearing, and then the wave generator 4 is assembled into the inner hole of the flexible wheel 3 to form a complete harmonic reducer.

[0056] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0057] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A flexible pulley, characterized in that: The invention comprises a gear ring (301), a cylinder (302) and a cylinder bottom (304), wherein the gear ring (301) is arranged on the outer peripheral wall of the cylinder (302), and the cylinder bottom (304) is connected to the bottom of the cylinder (302), and the flexible wheel meets the following requirements: Where T is the load capacity parameter of the flexspline, δ is the wall thickness of the gear ring, H is the hardness of the flexspline material, d m is the neutral circle diameter of the flexspline, w0 is the radial deformation of the flexspline, K R is the flexspline strength coefficient, k H is the material hardness coefficient, and s is the cylinder thickness at the flexspline gear ring.

2. The flexible spline according to claim 1, characterized in that: K R Satisfies: 1.24≤K R ≤1.

37.

3. The flexible spline according to claim 1, wherein: k H Satisfies: 0.28≤k H ≤0.

87.

4. The flexible spline according to claim 1, characterized in that: Wherein σ is the tensile strength of the flexspline.

5. The flexible spline according to any one of claims 1 to 4, characterized in that: The cylinder (302) includes a cylinder wall (3021) and a bottom corner (3022); the cylinder bottom (304) includes a flange (3041) and a diaphragm (3042); the diaphragm (3042) is located on the inner circumference of the flange (3041) and is connected to the inner wall of the flange (3041); the bottom corner (3022) is connected between the cylinder wall (3021) and the diaphragm (3042).

6. The flexible spline according to any one of claims 1 to 4, characterized in that: The cylinder (302) is a smooth cylinder.

7. The flexible spline according to any one of claims 1 to 4, characterized in that: The gear ring (301) is arranged at the outer edge end of the cylinder (302).

8. The flexible spline according to claim 7, characterized in that: A transition connecting section (303) is provided on one side of the gear ring (301) close to the cylinder bottom (304), and the thickness of the transition connecting section (303) decreases in a direction away from the gear ring (301). The end of the gear ring (301) is connected to the outer wall of the cylinder (302) through the transition connecting section (303).

9. A harmonic reducer, comprising a flexible wheel (3) and a rigid wheel (1), wherein the flexible wheel (3) and the rigid wheel (1) are meshed for transmission, and characterized in that: The flexible spline (3) is the flexible spline according to any one of claims 1 to 8.

10. The harmonic reducer according to claim 9, characterized in that: The harmonic reducer further comprises a bearing (2) and a wave generator (4), the rigid wheel (1) cooperates with the first end of the bearing (2), the flexible wheel (3) cooperates with the second end of the bearing (2), and the wave generator (4) is sleeved on the inner hole of the flexible wheel (3).

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