Cycloidal gear lubricating structure and speed reducer

Abstract

The cycloidal gear lubricating structure comprises a pin tooth seat, pin teeth and cycloidal gears, a plurality of pin tooth grooves are formed in the inner circumferential surface of the pin tooth seat, the pin teeth are distributed on the pin tooth grooves, the cycloidal gears are arranged on the inner side of the pin tooth seat, and the tooth surfaces of the cycloidal gears are meshed with the pin teeth; an oil injection hole is formed in the pin tooth seat between the adjacent pin teeth, the oil injection hole is communicated with the pin tooth grooves in the two adjacent sides, a circle of first groove is formed in the tooth surface of the cycloidal gear, and second grooves communicated with the first groove are formed in the tooth grooves in the tooth surface of the cycloidal gear in the axial direction of the cycloidal gear. The cycloidal gear has the advantages that the machining difficulty is lower, the machine does not need to be disassembled when lubricating grease is injected, low-speed operation can be met, the transmission process of the lubricating grease depends on the arrangement of the first groove in the cycloidal gear instead of the centrifugal force effect, and the cycloidal gear is suitable for cycloidal speed reducers with various reduction ratios and rotating speeds; and meanwhile, the friction loss of the cycloid speed reducer is reduced through the arrangement of the second groove, and the transmission efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of speed reducers, and specifically to a cycloid gear lubrication structure and a speed reducer. Background Art

[0002] As a core component in the field of precision transmission, cycloid speed reducers have been widely used in high-precision scenarios such as industrial robots, numerically controlled machine tools, and aerospace since the mid-20th century. Its core principle is based on the meshing transmission between cycloid tooth profiles and pin teeth, achieving the effects of high reduction ratio and compact volume through a planetary differential structure. With the acceleration of the localization process of industrial robots, the motion form of the cycloid gear is similar to that of the flexspline of a harmonic speed reducer to achieve the effects of speed reduction and force amplification. Currently, the core pain points of cycloid speed reducers are as follows: the sliding friction when the cycloid gear meshes with the pin gear is relatively large and difficult to improve. Cycloid speed reducers already have high requirements for machining accuracy. If the smoothness of the meshing surface between the cycloid gear and the pin gear is blindly improved, not only the effect is minimal, but the machining difficulty is greatly increased, and the cost is also significantly increased. Therefore, there is an urgent need to design a lubrication structure for cycloid speed reducers.

[0003] For example, the Chinese invention patent document with the publication number CN117366176A discloses an RV speed reducer. By setting an oil injection hole in the planet carrier, a through oil hole vertically in the needle roller, and a centrifugal hole horizontally in the needle roller that communicates with the through oil hole, a lubrication channel is formed. Lubricating grease can slide out from the oil injection hole, then fall into the through oil hole, and finally flow to the outside of the needle roller from the centrifugal hole under the action of centrifugal force, thereby lubricating the meshing part of the needle roller and the cycloid gear. Another example is the Chinese utility model patent document with the publication number CN218971757U, which discloses a high transmission efficiency cycloid pinwheel speed reducer. Similarly based on the centrifugal principle, the centrifugal force of the rotating speed reducer is used to throw the lubricating grease to the meshing part.

[0004] The above-mentioned technologies all adopt a centrifugal lubrication structure. The output stud and the cycloid gear are specially processed and designed to form a lubricating grease flow channel. By injecting lubricating grease into the output stud, the lubricating grease can be "thrown" to the meshing surface of the cycloid gear and the pin gear during the operation of the cycloid gear under the action of centrifugal force. However, this structural principle is limited by the need for a relatively large rotational speed for the centrifugal effect, so it is not suitable for cycloid speed reducers with a high reduction ratio, low rotational speed, and high torque. In addition, in order to ensure the constant spacing of the cycloid gears in the axial direction, spacer rings are placed on the end faces of adjacent cycloid gears in a cycloid speed reducer. However, during the operation of the cycloid speed reducer, the spacer rings will rotate relative to components such as the cycloid gear, the rotor, and the external output disk, resulting in friction and affecting the transmission efficiency of the speed reducer. Summary of the Invention

[0005] The technical problem to be solved by the present invention is how to improve the applicability and transmission efficiency of cycloid speed reducers.

[0006] To solve the above technical problems, the present invention provides the following technical solutions:

[0007] A cycloid gear lubrication structure includes a pin gear housing, pin gears, and a cycloid gear. A plurality of pin gear grooves are evenly spaced on the inner circumferential surface of the pin gear housing. The pin gears are correspondingly distributed on the pin gear grooves. Multiple sets of cycloid gears are arranged inside the pin gear housing, and the tooth surfaces of the cycloid gears mesh with the pin gears;

[0008] An oil injection hole is formed in the pin gear housing between adjacent pin gears. The oil injection hole communicates with the adjacent pin gear grooves on both sides. A first groove is formed in a circumferential direction along the tooth surface of the cycloid gear. Second grooves communicating with the first groove are arranged in the tooth grooves of the tooth surface of the cycloid gear along the axial direction of the cycloid gear.

[0009] The present invention directly opens an oil injection hole on the pin gear housing, and only processes the cycloid gear and the pin gear housing, which has lower processing difficulty, convenient assembly and high reliability. When injecting lubricating grease, there is no need to disassemble the machine, which increases the lubrication work efficiency and can also meet low-speed operation; and the process of transmitting the lubricating grease to the meshing surface depends on the setting of the first groove on the cycloid gear rather than the centrifugal force. Therefore, it can be applied to cycloid speed reducers with various reduction ratios and rotational speeds. At the same time, through the setting of the second groove, the lubricating grease in the first groove can flow from both ends of the second groove to the end face of the cycloid gear, thereby lubricating the spacer ring at the end face of the cycloid gear, reducing the friction of the spacer ring, and further reducing the friction loss of the cycloid speed reducer and improving the transmission efficiency.

[0010] Preferably, the number of oil injection holes is three groups, which are evenly distributed along the circumferential direction of the pin gear housing.

[0011] Preferably, the first groove is arranged at the center position of the tooth surface of the cycloid gear.

[0012] Preferably, the first groove and the second groove have the same depth.

[0013] Preferably, multiple groups of bearing holes are arranged on the cycloid gear.

[0014] Preferably, a shaft hole is arranged at the center of the cycloid gear, and the bearing holes are located between the shaft hole and the tooth surface of the cycloid gear.

[0015] Preferably, weight-reducing holes are also arranged on the cycloid gear.

[0016] Preferably, mounting holes for mounting the pin gears are arranged on the pin gear housing on the circumferential surface of the pin gear groove.

[0017] Preferably, a plurality of fixing holes are also arranged on the pin gear housing.

[0018] Preferably, the present invention also provides a speed reducer, including the above cycloid gear lubrication structure.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] In the present invention, an oil injection hole is directly opened on the pin tooth seat, and only the cycloid gear and the pin tooth seat are processed, which has lower processing difficulty, convenient assembly and high reliability. When injecting grease, there is no need to disassemble the machine, which increases the lubrication work efficiency and can also meet low-speed operation. And the process of transferring the lubricating grease to the meshing surface depends on the setting of the first groove on the cycloid gear rather than the centrifugal force. Therefore, it can be applied to cycloid speed reducers with various reduction ratios and rotational speeds. At the same time, through the setting of the second groove, the lubricating grease in the first groove can flow from both ends of the second groove to the end face of the cycloid gear, thereby lubricating the spacer ring at the end face of the cycloid gear, reducing the friction of the spacer ring, and further reducing the friction loss of the cycloid speed reducer and improving the transmission efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a schematic structural diagram of an embodiment of the present invention;

[0022] Figure 2 is a schematic structural diagram of the pin tooth seat of an embodiment of the present invention;

[0023] Figure 3 is a schematic structural diagram of the cycloid gear of an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] To facilitate the understanding of the technical solution of the present invention by those skilled in the art, the technical solution of the present invention will be further described below with reference to the accompanying drawings of the specification.

[0025] In this application, unless otherwise clearly defined and limited, terms such as "installation", "connection", "connection", "fixation" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection, an electrical connection, or a communication connection; it can be directly connected, or indirectly connected through an intermediate medium, and can be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific situations.

[0026] In this application, unless otherwise clearly defined and limited, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of this application, "a plurality" means two or more, unless otherwise clearly specifically defined.

[0027] Refer to Figure 1 and Figure 2, this embodiment discloses a cycloid gear lubrication structure, including a pin gear housing 1, pin gears 2, and cycloid gears 3. A plurality of pin gear grooves 101 are evenly spaced on the inner circumferential surface of the pin gear housing 1. The pin gears 2 are correspondingly distributed on the pin gear grooves 101. A plurality of groups of cycloid gears 3 are arranged inside the pin gear housing 1, and the tooth surfaces of the cycloid gears 3 are engaged with the pin gears 2. In this embodiment, two groups of cycloid gears 3 are provided, but not limited to two groups, and can be set according to actual needs.

[0028] Specifically, the pin gear housing 1 is further provided with a plurality of fixing holes 102 for fixing the lubrication structure on the outer rotor motor; on the pin gear housing 1 on the circumferential surface of the pin gear groove 101, there is an installation hole 103, and the pin gear 2 can be rotatably arranged on the pin gear housing 1 through a fixing bolt passing through the installation hole 103.

[0029] On the pin gear housing 1 between adjacent pin gears 2, there are oil injection holes 104. In this embodiment, the number of oil injection holes 104 is three groups, and they are evenly distributed along the circumferential direction of the pin gear housing 1. However, the number of oil injection holes 104 is not limited to three groups and can be set according to actual needs. The oil injection holes 104 are communicated with the adjacent pin gear grooves 101 on both sides, so that lubricating grease can enter the pin gear grooves 101 from the oil injection holes to provide lubrication for the pin gears 2. At the same time, the lubricating grease can also be transmitted to the cycloid gears 3 through the pin gears 2 for lubrication, and the lubricating grease on the cycloid gears 3 is then transmitted to other pin gears to ensure the lubrication effect of the lubrication structure.

[0030] Furthermore, the side of the oil injection hole 104 facing the cycloid gear 3 is in an open shape, so that the lubricating grease in the oil injection hole 104 can directly lubricate the cycloid gear 3.

[0031] Refer to Figure 3 , a first groove 301 is provided along the circumferential direction of the tooth surface of the cycloid gear 3, and the first groove 301 is arranged at the center position of the tooth surface of the cycloid gear 3. In the tooth groove of the tooth surface of the cycloid gear 3, a second groove 302 communicated with the first groove 301 is arranged along the axial direction of the cycloid gear 3. In this embodiment, the depths of the first groove 301 and the second groove 302 are the same. The first groove 301 stores lubricating grease, so that the tooth surface of the cycloid gear 3 always stores lubricating grease, which can provide lubricating grease between the pin gears 2 and the cycloid gears 3, ensuring that lubricating grease can be injected without disassembling the machine, and enabling the lubrication structure to obtain better lubrication conditions. In this embodiment, the number of the second grooves 302 is three, and they are evenly distributed along the circumferential direction of the cycloid gear 3.

[0032] In addition, in this embodiment, during the machining process of the cycloid gear 3, by selecting a thinner tool, a first groove 301 similar to the tooth surface shape of the cycloid gear 3 is machined on the cycloid gear 3, ensuring that there is sufficient meshing area on each tooth surface of the cycloid gear 3 (a groove is opened in the middle, and the meshing surfaces on both sides remain unchanged), and the influence on the transmission performance and durability is small. In addition, through the setting of the second groove 302, part of the lubricating grease in the first groove 301 can be introduced to the end face of the cycloid gear 3, thereby lubricating the spacer ring, the rotor, the cycloid gear, and the external support disk, reducing the frictional loss, and improving the transmission efficiency.

[0033] Furthermore, multiple groups of bearing holes 303 are provided on the cycloid gear 3, and a shaft hole 304 is provided at the center of the cycloid gear 3. The bearing holes 303 are located between the shaft hole 304 and the tooth surface of the cycloid gear 3.

[0034] Still further, a weight reduction hole 305 is also provided on the cycloid gear 3.

[0035] In this embodiment, a speed reducer is also disclosed, including the above cycloid gear lubrication structure. By combining this speed reducer with an outer rotor motor, a larger torque can be obtained.

[0036] In summary, in this embodiment, an oil injection hole 104 is directly opened on the pin tooth holder 1, and only the cycloid gear 3 and the pin tooth holder 1 are specially designed and machined. The machining difficulty is lower, and only the distance between the tool and the blank needs to be simply adjusted, and the assembly is convenient and the reliability is high. And the process of transferring the lubricating grease to the meshing surface depends on the setting of the first groove 301 on the cycloid gear 3 rather than the centrifugal force. Therefore, it can be applied to cycloid speed reducers with various reduction ratios and speeds. It should be noted that although the existing centrifugal lubrication mechanism in the prior art can also be disassembled without disassembly, the effect is not good at low speeds. Low speed and heavy torque are one of the characteristics of cycloid speed reducers. Theoretically, it is unreasonable to maintain a high speed for lubrication. And this lubrication structure can ensure that it can be disassembled without disassembly and has a good effect at low speeds, increasing the lubrication work efficiency.

[0037] At the same time, through the setting of the second groove 302, the lubricating grease in the first groove 301 can flow from both ends of the second groove 302 to the end face of the cycloid gear, thereby lubricating the spacer ring at the end face of the cycloid gear, reducing the friction of the spacer ring, and further reducing the frictional loss of the cycloid speed reducer, improving the transmission efficiency, and better exerting the advantage of the relatively high single-stage transmission ratio of the cycloid speed reducer. This speed reducer is applicable to an outer rotor motor. Based on the characteristic of the larger inner diameter of the outer rotor motor, the pin tooth holder 1 is placed, improving the space utilization rate and obtaining the advantage of the high torque of the outer rotor motor.

[0038] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above-described exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, in any regard, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be encompassed within the present invention, and any reference signs in the claims should not be regarded as limiting the claims involved.

[0039] The above-described embodiments merely represent the implementation manners of the invention. The protection scope of the present invention is not limited to the above embodiments only. For those skilled in the art, without departing from the concept of the present invention, several variations and improvements can be made, and these all belong to the protection scope of the present invention.

Claims

1. A cycloid gear lubrication structure, characterized in that: It includes a pin tooth base, pin teeth, and a cycloid gear. Multiple pin tooth grooves are evenly spaced on the inner circumferential surface of the pin tooth base. The pin teeth are correspondingly distributed on the pin tooth grooves. Multiple sets of cycloid gears are arranged inside the pin tooth base, and the tooth surfaces of the cycloid gears mesh with the pin teeth; An oil injection hole is provided on the pin tooth base between adjacent pin teeth. The oil injection hole communicates with the pin tooth grooves on both adjacent sides. A first groove is provided in a circumferential direction along the tooth surface of the cycloid gear, and a second groove communicating with the first groove is provided in an axial direction along the tooth groove of the tooth surface of the cycloid gear.

2. The cycloid gear lubrication structure according to claim 1, characterized in that: The number of oil injection holes is three groups, which are evenly distributed along the circumferential direction of the pin tooth base.

3. A cycloid gear lubrication structure according to claim 1, characterized in that: The first groove is provided at the center position of the tooth surface of the cycloid gear.

4. A cycloid gear lubrication structure according to claim 1, characterized in that: The first groove and the second groove have the same depth.

5. The cycloid gear lubrication structure according to claim 1, characterized in that: Multiple sets of bearing holes are provided on the cycloid gear.

6. The cycloid gear lubrication structure according to claim 5, wherein: A shaft hole is provided at the center of the cycloid gear, and the bearing holes are located between the shaft hole and the tooth surface of the cycloid gear.

7. A cycloid gear lubrication structure according to claim 1, characterized in that: Weight reduction holes are also provided on the cycloid gear.

8. A cycloid gear lubrication structure according to claim 1, characterized in that: Installation holes for installing the pin teeth are provided on the pin tooth base on the circumferential surface of the pin tooth groove.

9. The cycloid gear lubrication structure according to claim 1, characterized in that: Multiple fixing holes are also provided on the pin tooth base.

10. A speed reducer, characterized in that: It includes the cycloid gear lubrication structure according to any one of claims 1-9.

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