Pin wheel housing and RV speed reducer

Abstract

The invention discloses a pin wheel housing and an RV speed reducer, and relates to the technical field of speed reducers, the pin wheel housing comprises a base body and a groove, a plurality of tooth grooves are evenly distributed in the peripheral wall of an inner hole of the base body, and the tooth grooves are used for being matched with tooth pins so as to play a role in positioning and guiding, and it is guaranteed that the tooth pins are located at correct positions and motion trails. A connecting part is formed between every two adjacent tooth grooves, a groove is formed in each connecting part, and a first edge part and a second edge part are formed between each groove and the corresponding two adjacent tooth grooves respectively. And the first edge part and the second edge part can enable the connecting part to have certain strength, so that the edge of the groove is prevented from being damaged and cracked, and the reliability of the pin wheel housing is improved. By arranging the groove, the fit clearance between the cycloidal gear and the connecting part can be increased, and the shear stress can be reduced when the fit clearance is increased, so that the power loss caused by grease stirring is reduced, and the transmission efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of reducers, and in particular to a pin gear housing and an RV reducer. Background Art

[0002] In the related art, the RV reducer is composed of a planetary gear reducer and a cycloidal pinwheel reducer, which has the advantages of compact structure, large transmission ratio, low vibration, low noise, low energy consumption, etc. The traditional RV reducer has a pinion housing and a cycloidal wheel, and a plurality of tooth grooves are arranged at intervals on the inner side of the pinion housing. Due to the rotation of the cycloidal wheel, the connecting part between two adjacent tooth grooves is subjected to a large shear stress, which increases the grease stirring loss of the RV reducer and affects the transmission efficiency. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a pinion housing, which can reduce the shear stress on the connection part by providing a groove at the connection part between two adjacent tooth grooves, thereby reducing the power loss caused by grease stirring and improving the transmission efficiency.

[0004] The present invention also provides an RV reducer having the above-mentioned pin gear housing.

[0005] The needle tooth housing according to the first embodiment of the present invention comprises:

[0006] A base body, provided with an inner hole and a plurality of tooth grooves evenly arranged around the peripheral wall of the inner hole, and a connecting portion is formed between two adjacent tooth grooves;

[0007] A groove is provided at the connecting portion, and a first edge portion and a second edge portion are formed between the groove and two adjacent tooth grooves respectively.

[0008] The needle tooth housing according to the embodiment of the present invention has at least the following beneficial effects:

[0009] A plurality of tooth grooves are evenly distributed on the circumferential wall of the inner hole of the base body, and the tooth grooves are used to cooperate with the tooth pins to play a role in positioning and guiding, so as to ensure that the tooth pins are in the correct position and movement trajectory. A connecting portion is formed between two adjacent tooth grooves, and a groove is provided on the connecting portion, and a first edge portion and a second edge portion are respectively formed between the groove and the two adjacent tooth grooves. The first edge portion and the second edge portion can make the connecting portion have a certain strength, ensuring that the edges of the grooves will not be damaged or cracked, thereby improving the reliability of the needle tooth housing. By providing the grooves, the fitting clearance between the cycloid wheel and the connecting portion can be increased. When the fitting clearance is increased, the shear stress can be reduced, thereby reducing the power loss caused by the stirring of the grease, so as to improve the transmission efficiency.

[0010] According to some embodiments of the present invention, the groove is in an arc shape with a radius of r, and the tooth groove is in an arc shape with a radius of R, satisfying: 1 / 8≤r / R≤5 / 8.

[0011] According to some embodiments of the present invention, the length of the first edge portion along the circumference of the inner hole is L1, the length of the second edge portion along the circumference of the inner hole is L2, the tooth groove is arc-shaped with a radius R, satisfying: 3 / 80≤L1 / R≤1 / 16, 3 / 80≤L2 / R≤1 / 16.

[0012] According to some embodiments of the present invention, along the circumference of the inner hole, the length L1 of the first edge portion is equal to the length L2 of the second edge portion.

[0013] According to some embodiments of the present invention, the length of the first edge portion along the circumference of the inner hole is L1, and the length of the second edge portion along the circumference of the inner hole is L2, satisfying: 0.15mm≤L1≤0.25mm, 0.15mm≤L2≤0.25mm.

[0014] According to some embodiments of the present invention, the tooth groove is arc-shaped with a radius of R, and along the radial direction of the tooth groove, the minimum distance between the side wall of the tooth groove and the side wall of the adjacent groove is s, satisfying: s / R≥3 / 80.

[0015] According to some embodiments of the present invention, the depth of the groove is t, satisfying: 0.5 mm≤t≤2.5 mm.

[0016] According to some embodiments of the present invention, the depth of the groove is t, the tooth groove is arc-shaped with a radius of R, and satisfies: t≤R.

[0017] According to some embodiments of the present invention, the grooves are configured to be symmetrical along a radial direction of the inner hole.

[0018] According to some embodiments of the present invention, both the groove and the tooth groove extend along the axial direction of the inner hole, and the axial dimension of the groove is h, and the axial dimension of the tooth groove is H, satisfying: h≤H.

[0019] According to some embodiments of the present invention, the groove is formed by wire cutting.

[0020] The RV reducer according to the second embodiment of the present invention includes the pin gear housing described in the above embodiment.

[0021] The RV reducer according to the embodiment of the present invention has at least the following beneficial effects:

[0022] The needle tooth housing of the first aspect embodiment is adopted, and a plurality of tooth grooves are evenly distributed on the circumferential wall of the inner hole of the base of the needle tooth housing, and the tooth grooves are used to cooperate with the tooth pins to play a role of positioning and guiding, thereby ensuring that the tooth pins are in the correct position and motion trajectory. A connecting portion is formed between two adjacent tooth grooves, and a groove is provided on the connecting portion, and a first edge portion and a second edge portion are respectively formed between the groove and the two adjacent tooth grooves. The first edge portion and the second edge portion can make the connecting portion have a certain strength, ensuring that the edges of the grooves will not be damaged or cracked, thereby improving the reliability of the needle tooth housing. By providing the grooves, the fitting clearance between the cycloid wheel and the connecting portion can be increased. When the fitting clearance is increased, the shear stress can be reduced, thereby reducing the power consumption loss caused by the stirring of the grease, so as to improve the transmission efficiency.

[0023] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0025] Figure 1 This is a schematic structural diagram of an RV reducer according to an embodiment of the present invention;

[0026] Figure 2 for Figure 1 The enlarged schematic diagram of point A in the middle;

[0027] Figure 3 A schematic diagram of the structure of a pin gear housing according to an embodiment of the present invention;

[0028] Figure 4 for Figure 3 The enlarged schematic diagram of point B in the middle;

[0029] Figure 5 It is an enlarged view of the structure of the needle tooth housing part of another embodiment of the present invention;

[0030] Figure 6 It is an enlarged view of the structure of the needle tooth housing part of another embodiment of the present invention;

[0031] Figure 7 It is an enlarged view of the structure of the needle tooth housing part of another embodiment of the present invention;

[0032] Figure 8 It is an enlarged view of the structure of the needle tooth housing part of another embodiment of the present invention;

[0033] Fig. 9 A schematic diagram of the structure of a pin gear housing according to an embodiment of the present invention;

[0034] Fig.10 for Fig. 9Enlarged schematic diagram of point C in the middle.

[0035] Figure Number:

[0036] RV reducer 1000;

[0037] Needle tooth housing 100; base 110; inner hole 111; tooth groove 112; connecting portion 113; groove 114; first edge portion 115; second edge portion 116;

[0038] Cycloid wheel 200;

[0039] Tooth pin 300. DETAILED DESCRIPTION

[0040] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0041] In the description of the present invention, it should be understood that descriptions involving orientation, such as orientation or positional relationship indicated as up, down, etc., are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention 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 should not be understood as a limitation on the present invention.

[0042] In the description of the present invention, "a plurality" means more than two. If there is a description of "first" or "second", it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0043] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0044] The RV reducer is a transmission mechanism developed on the basis of traditional cycloid pinwheel and planetary gear transmission devices. It has become the core component of industrial robot joint drive due to its high transmission stiffness, large transmission ratio (usually 30-260), stable transmission, small inertia, large output torque, small size, and strong impact resistance. The RV reducer has a pin gear housing, and a plurality of tooth grooves are arranged at intervals on the inner side of the pin gear housing. There are tooth pins in the tooth grooves, and the cycloid wheel can cooperate with different tooth pins during the rotation process. Due to the rotation of the cycloid wheel, the shear stress on the connection between the two adjacent tooth grooves is large, resulting in an increase in the grease stirring loss of the RV reducer. Among them, the transmission efficiency of the RV reducer is 80%-85%, 6%-9% of the power consumption comes from the oil stirring loss, and the other part comes from the friction power consumption. When the oil stirring loss is too large, it will affect the transmission efficiency of the RV reducer.

[0045] Based on this, the present invention provides a needle tooth housing, which can reduce the shear stress on the connecting part by setting a groove at the connecting part between two adjacent tooth grooves, thereby reducing the power loss caused by grease stirring and improving the transmission efficiency.

[0046] The following is a description with reference to the accompanying drawings:

[0047] Reference Figure 1 and Figure 2 As shown, a needle tooth housing 100 according to an embodiment of the present invention comprises a base 110, the base 110 is provided with an inner hole 111, a plurality of tooth grooves 112 are provided on the peripheral wall of the inner hole 111, the plurality of tooth grooves 112 are evenly distributed and arranged around the inner hole 111, and a tooth pin 300 is arranged in the tooth groove 112. A connecting portion 113 is formed between two adjacent tooth grooves 112, the connecting portion 113 is provided with a groove 114 whose opening is arranged toward the inner hole 111, and a first edge portion 115 and a second edge portion 116 are formed between the groove 114 and the two adjacent tooth grooves 112, respectively.

[0048] It is understandable that when the cycloid wheel 200 is set in the inner hole 111, the cycloid wheel 200 can cooperate with the tooth pin 300. And when the cycloid wheel 200 rotates, it can engage or disengage with the tooth pin 300 at different positions. In the process of the cycloid wheel 200 and the tooth pin 300 engaging, the tooth portion of the cycloid wheel 200 is arranged toward the connecting portion 113. Since the connecting portion 113 is provided with a groove 114, the distance δ between the tooth portion of the cycloid wheel 200 and the connecting portion 113 can be increased. According to the shear stress formula: T∝(μ, h, D2, A, 1 / δ), T represents shear stress, μ represents grease viscosity; h represents tooth height; D represents outer diameter, A represents the area of ​​the outer peripheral surface of the gear, and 1 / δ represents the gear matching clearance. It can be seen that T and δ are negatively correlated, and the larger δ is, the smaller T is. Therefore, by increasing the distance between the tooth portion of the cycloid wheel 200 and the connecting portion 113, the shear stress on the connecting portion 113 can be reduced, thereby reducing the power loss caused by the agitation of the grease, so as to improve the transmission efficiency. The first edge portion 115 and the second edge portion 116 formed between the groove 114 and the two adjacent tooth grooves 112 can make the connecting portion 113 have a certain strength, ensuring that the edge of the groove 114 will not be damaged or cracked, thereby improving the reliability of the pin gear housing 100.

[0049] It should be noted that there are multiple connecting parts 113, and each connecting part 113 can be provided with a groove 114, so as to ensure that the needle tooth housing 100 has the function of reducing shear stress at each connecting part 113. In another embodiment, only a part of the connecting parts 113 can be provided with a groove 114. Among them, one connecting part 113 can be provided with one groove 114 or multiple grooves 114. For example, when the connecting part 113 is provided with multiple grooves 114, the multiple grooves 114 are arranged along the circumference of the inner hole 111; or the multiple grooves 114 are arranged along the axial direction of the inner hole 111. The appropriate solution is selected according to the actual situation.

[0050] Reference Figure 3 and Figure 4As shown, in the embodiment of the present invention, the groove 114 is arc-shaped and has a radius of r, and the tooth groove 112 is arc-shaped and has a radius of R, satisfying: 1 / 8≤r / R≤5 / 8. For example, r / R can be 1 / 4, 3 / 8, 1 / 2. It can be understood that the groove 114 is arc-shaped, which is easy to process, and is similar to the shape of the tooth portion of the cycloidal wheel 200, which can ensure that the tooth portion of the cycloidal wheel 200 and the groove 114 meet certain clearance requirements. At the same time, the material that needs to be cut from the needle tooth housing 100 is reduced, so that the connecting portion 113 has a certain strength. The tooth groove 112 is arc-shaped, which can adapt to the cylindrical tooth pin 300, and the relevant process is relatively mature and easy to manufacture. When r / R<1 / 8, the groove 114 is small and it is difficult to reduce the shear stress; when r / R>5 / 8, the groove 114 is large, which easily leads to a decrease in the strength of the connecting portion 113. During long-term operation, the needle tooth housing 100 is prone to cracking, deformation and other adverse effects at the connection part 113, which shortens the service life of the needle tooth housing 100. Therefore, the size relationship between the groove 114 and the tooth groove 112 is reasonably designed to reduce the shear stress while ensuring the strength requirement of the connection part 113, which can improve the service life of the needle tooth housing 100.

[0051] In another embodiment, the shape of the groove 114 can also be Figure 5 The rectangle shown in , or refer to Figure 6 As shown, the groove 114 has an edge that is concentrically arranged with the adjacent arc-shaped tooth groove 112, so that the volume of the groove 114 gradually increases along the radial direction of the inner hole 111, thereby storing more lubricating oil and improving the lubrication effect. The groove 114 can be configured to be symmetrically arranged along the radial direction of the inner hole 111 to balance the force. Figure 7 and Figure 8 As shown, the shape of the groove 114 can also be an asymmetrical design, and the volume of the end of the groove 114 away from the center of the inner hole 111 is larger than the opening of the groove 114, which is convenient for storing lubricating oil, improving wear, and increasing the service life of the RV reducer. The appropriate solution is selected according to the actual situation.

[0052] In the embodiment of the present invention, the depth of the groove 114 is t, and the shape of the groove 114 can be Figure 5 The rectangle shown in , or Figure 6 , Figure 7 and Figure 8The shape shown in . The groove 114 can be configured to be symmetrically arranged along the radial direction of the inner hole 111, or it can be an asymmetrical design. The appropriate solution is selected according to the actual situation. The tooth groove 112 is in an arc shape and has a radius R, satisfying t≤R. For example, it satisfies: 0.5mm≤t≤2.5mm. t can be 0.6mm, 0.8mm, 1mm, 1.5mm, etc. It can be understood that if the depth of the groove 114 is too large, it is easy to reduce the overall strength of the connecting part 113 and increase the difficulty of processing. Therefore, a reasonable design of the depth of the groove 114 can reduce the shear stress while ensuring that the connecting part 113 has a suitable strength.

[0053] Reference Figure 4 As shown, in the embodiment of the present invention, the length of the first edge portion 115 along the circumference of the inner hole 111 is L1, and the length of the second edge portion 116 along the axis of the inner hole 111 is L2, which satisfies: 3 / 80≤L1 / R≤1 / 16, 3 / 80≤L2 / R≤1 / 16. For example, L1 / R can be 1 / 20, 9 / 160, etc., L2 / R can be 1 / 20, 9 / 160, etc., and L1 and L2 can be equal or unequal. It can be understood that, assuming that L1 / R<3 / 80, L2 / R<3 / 80, it is easy to cause the strength of the connecting portion 113 to decrease, and the first edge portion 115 and the second edge portion 116 are easy to deform, break, etc. when subjected to pressure, and the strength of the needle tooth housing 100 is reduced, and the service life is reduced. Assuming that L1 / R>1 / 16, L2 / R>1 / 16, the opening of the groove 114 is small, and it is difficult to reduce the shear stress. The power loss caused by the grease stirring is large, and the transmission efficiency is low. Therefore, the size relationship between the first edge portion 115 and the tooth groove 112 is reasonably designed, and the size relationship between the second edge portion 116 and the tooth groove 112 is reasonably designed. While ensuring the strength of the first edge portion 115 and the second edge portion 116, the shear stress on the connecting portion 113 can be reduced, the power loss caused by the grease stirring is reduced, and the transmission efficiency is improved.

[0054] Continue to refer to Figure 4 As shown, in the embodiment of the present invention, the length L1 of the first edge portion 115 along the circumference of the inner hole 111 satisfies: 0.15mm≤L1≤0.25mm, and the length L2 of the second edge portion 116 along the axis of the inner hole 111 satisfies: 0.15mm≤L2≤0.25mm. For example, L1 can be 0.16mm, 0.18mm, 0.2mm, 0.23mm; L2 can be 0.16mm, 0.18mm, 0.2mm, 0.23mm. Therefore, the reasonable design of the dimensional parameters of the first edge portion 115 and the second edge portion 116 can ensure that the connecting portion 113 has a certain strength, effectively improve the deformation and fracture of the connecting portion 113, thereby improving the overall strength of the needle tooth housing 100 and the service life of the needle tooth housing 100.

[0055] In order to ensure the overall strength of the connection part 113, it is also necessary to limit the distance between the side wall of the tooth groove 112 and the adjacent groove 114. For example, the minimum distance between the side wall of the tooth groove 112 and the adjacent groove 114 is s, and the tooth groove 112 is arc-shaped with a radius of R, satisfying: s / R≥3 / 80. Limiting the minimum distance between the side wall of the tooth groove 112 and the adjacent groove 114 can effectively improve the unfavorable conditions such as fracture and deformation of the connection part 113 caused by too thin wall thickness, and the overall strength of the needle tooth housing 100 is high and has a long service life.

[0056] Reference Fig. 9 and Fig.10 As shown, in the embodiment of the present invention, the groove 114 and the tooth groove 112 are both arranged to extend along the axial direction of the inner hole 111, the axial dimension of the groove 114 is h, and the axial dimension of the tooth groove 112 is H, satisfying: h≤H, for example, h and H are equal. The two ends of the tooth groove 112 extend to the two end walls of the base 110 along its axial direction, that is, the two ends of the tooth groove 112 penetrate the two end walls of the base 110. The two ends of the groove 114 can also extend to the two end walls of the base 110 and penetrate the two end walls of the base 110. Therefore, in the production and manufacturing of the needle tooth housing 100, the groove 114 can be processed by slow wire cutting to simplify the production process, improve manufacturing accuracy, and reduce production costs. In another embodiment, the groove 114 can also be a groove that only has one end that penetrates one end wall of the base 110, and the other end of the groove 114 does not penetrate the other end wall of the base 110. Alternatively, the groove 114 can also be a groove that does not penetrate the end wall of the base 110 at both ends. In another embodiment, the groove 114 may have only one groove section, or may include multiple groove sections, and the multiple groove sections are arranged along the axial direction of the inner hole 111, or the multiple groove sections are arranged along the circumferential direction of the inner hole 111. The multiple groove sections may be connected or not connected, and a suitable solution is selected according to the actual situation.

[0057] In an embodiment of the present invention, the needle tooth housing 100 can be made of ductile iron, for example, QT500. Ductile iron has higher strength and toughness, and has better tensile, bending and impact resistance than gray cast iron. This makes ductile iron more reliable and safer in applications that need to withstand larger loads and impact loads. Ductile iron also has good fatigue strength and can maintain a longer service life under repeated cyclic loads. This makes ductile iron widely used in environments subject to cyclic loads and vibrations, such as automotive engine parts, wind power generation machinery parts, etc. Compared with other materials, such as steel and aluminum alloys, ductile iron has lower raw material costs and production costs. Therefore, the needle tooth housing 100 made of ductile iron is easy to process, has high strength and toughness, and is low in cost.

[0058] Reference Figure 1 As shown, an RV reducer 1000 of an embodiment of the present invention comprises a pin gear housing 100 of the above embodiment, at least one cycloidal wheel 200 and a plurality of tooth pins 300, and the plurality of tooth pins 300 are correspondingly arranged in a plurality of tooth grooves 112. By adopting the pin gear housing 100 of the above embodiment, a plurality of tooth grooves 112 are evenly arranged on the peripheral wall of the inner hole 111 of the base 110 of the pin gear housing 100, and the tooth grooves 112 cooperate with the tooth pins 300 to play a role in positioning and guiding, so as to ensure that the tooth pins 300 are in the correct position and motion trajectory. A connecting portion 113 is formed between two adjacent tooth grooves 112, and a groove 114 is provided on the connecting portion 113, and a first edge portion 115 and a second edge portion 116 are respectively formed between the groove 114 and the two adjacent tooth grooves 112. The first edge portion 115 and the second edge portion 116 can make the connecting portion 113 have a certain strength, ensure that the edge of the groove 114 will not be damaged or cracked, thereby improving the reliability of the pin gear housing 100. By providing the groove 114, the fitting clearance between the cycloid wheel 200 and the connecting portion 113 can be increased. When the fitting clearance is increased, the shear stress can be reduced, thereby reducing the power loss caused by grease stirring, so as to improve the transmission efficiency.

[0059] The RV reducer 1000 also includes an input gear, a planetary gear, a crankshaft and a support flange. Three planetary gears are provided and mesh with the input gear. Three crankshafts are provided and fixedly connected to the corresponding planetary gears. The crankshaft is passed through the support flange, and the support flange is connected to the pinion housing 100 through a bearing. Two cycloid wheels 200 are provided and are both sleeved on the crankshaft. The phase difference between the two cycloid wheels 200 is 180° to balance the load, reduce the tooth force, reduce the reverse clearance and improve the motion accuracy. Therefore, the RV reducer 1000 has a two-stage reduction, the first stage reduction is a spur gear reduction mechanism, and the second stage reduction is a differential gear reduction mechanism. When the RV reducer 1000 is working, the motor drives the input gear to rotate, and the input gear drives the three planetary gears to rotate to complete the first stage reduction; the planetary gear drives the crankshaft to rotate, and the crankshaft drives the cycloid wheel 200 to rotate and deflect. Since the number of teeth of the cycloid wheel 200 is one or two less than the number of the tooth pins 300, when the pin gear housing 100 is fixed, the cycloid wheel 200 will revolve while rotating. That is, when the crankshaft rotates one circle, the cycloid wheel 200 rotates one tooth in the opposite direction of the crankshaft, and the cycloid wheel 200 is the output end, thereby completing the second stage of reduction. Therefore, the RV reducer 1000 has the characteristics of large transmission ratio and small size.

[0060] Since the RV reducer 1000 adopts all the technical solutions of the pin gear housing 100 of the above embodiment, it has at least all the beneficial effects brought by the technical solutions of the above embodiment, which will not be repeated here.

[0061] Among them, the RV reducer 1000 can be applied to industrial robots, which can be handling robots, welding robots, assembly robots, processing robots, spraying robots, cleaning robots, collaborative robots, etc. The RV reducer 1000 adopts the cycloid pinwheel transmission principle, and the meshing process is in a continuous rolling state, thereby achieving smooth operation and reducing the generation of vibration and noise. The RV reducer 1000 also has high-precision transmission characteristics and can provide accurate position control and positioning capabilities. By reducing the tooth clearance, return error and reverse clearance of the cycloid pinwheel and cycloid gear, the RV reducer 1000 can achieve high-precision rotation output, allowing industrial robots to accurately position and perform complex trajectory movements, improving work efficiency and operating accuracy.

[0062] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. Needle gear housing, characterized in that: include: A base body is provided with an inner hole and a plurality of tooth grooves evenly arranged around the peripheral wall of the inner hole, and a connecting portion is formed between two adjacent tooth grooves; A groove is provided at the connecting portion, and a first edge portion and a second edge portion are formed between the groove and two adjacent tooth grooves respectively.

2. The needle tooth housing according to claim 1, characterized in that: The groove is in an arc shape with a radius of r, and the tooth groove is in an arc shape with a radius of R, satisfying: 1 / 8≤r / R≤5 / 8.

3. The needle tooth housing according to claim 1 or 2, characterized in that: The length of the first edge portion along the circumference of the inner hole is L1, and the length of the second edge portion along the circumference of the inner hole is L2, satisfying: 0.15mm≤L1≤0.25mm, 0.15mm≤L2≤0.25mm.

4. The needle tooth housing according to claim 1, characterized in that: The length of the first edge portion along the circumference of the inner hole is L1, the length of the second edge portion along the circumference of the inner hole is L2, the tooth groove is arc-shaped with a radius of R, satisfying: 3 / 80≤L1 / R≤1 / 16, 3 / 80≤L2 / R≤1 / 16.

5. The needle tooth housing according to claim 4, characterized in that: Along the circumference of the inner hole, the length L1 of the first edge portion is equal to the length L2 of the second edge portion.

6. The needle tooth housing according to claim 1, characterized in that: The tooth groove is arc-shaped and has a radius of R. Along the radial direction of the tooth groove, the minimum distance between the side wall of the tooth groove and the side wall of the adjacent groove is s, satisfying: s / R≥3 / 80.

7. The needle tooth housing according to claim 1, characterized in that: The depth of the groove is t, which satisfies: 0.5mm≤t≤2.5mm.

8. The needle tooth housing according to claim 1 or 7, characterized in that: The depth of the groove is t, and the tooth groove is arc-shaped with a radius of R, satisfying: t≤R.

9. The needle tooth housing according to claim 1, characterized in that: The grooves are configured to be symmetrical along a radial direction of the inner hole.

10. The needle tooth housing according to claim 1, characterized in that: The groove and the tooth groove both extend along the axial direction of the inner hole, and the axial dimension of the groove is h, and the axial dimension of the tooth groove is H, satisfying: h≤H.

11. The needle tooth housing according to claim 1, characterized in that: The groove is formed by wire cutting. 12.RV reducer, characterized in that: include: The needle tooth housing according to any one of claims 1 to 11; A plurality of tooth pins are respectively arranged in the tooth grooves; At least one cycloidal wheel is installed in the inner hole, and the cycloidal wheel includes an outer tooth portion meshing with the tooth pin.

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