Internally Engaged Transmission Mechanism

Abstract

An internal engagement transmission mechanism is disclosed that includes an outer wheel and an inner wheel. The outer wheel has outer wheel internal teeth and includes an outer wheel internal tooth tip and an outer wheel internal tooth waist. The inner wheel has inner wheel external teeth and includes an inner wheel external tooth tip and an inner wheel external tooth waist. The inner wheel and outer wheel form an internal engagement transmission through the inner wheel external tooth waist and the outer wheel internal tooth waist. The outer wheel internal tooth waist and the inner wheel external tooth waist have the same shape and matching curved surfaces. The inner wheel external tooth waist and the outer wheel internal tooth waist form a surface contact engagement, and as the inner wheel rotates, the contact area between the inner wheel external tooth waist and the outer wheel internal tooth waist gradually increases to a maximum value and then gradually decreases. The internal engagement transmission mechanism reduces stress concentration during engagement between the inner wheel and outer wheel, improving the service life of the teeth.

Description

[Technical field]

[0001] This application relates to transmission mechanisms, and more particularly to internally engaging transmission mechanisms. [Background technology]

[0002] Existing internal engagement transmission mechanisms mainly have planetary gear transmission, harmonic transmission, cycloid pinwheel transmission and so on. Planetary gear transmission devices mainly use involute gear engagement. When the difference in the number of teeth between the outer wheel internal teeth and the inner wheel external teeth is large, interference can be avoided, and the single-stage speed ratio is low. Harmonic transmission also uses involute gear engagement. This can achieve engagement with one tooth difference or two teeth difference, but it is necessary to use soft gears as the outer teeth of the inner wheel. The above interference problem can only be solved through the deformation of the inner wheel external teeth. The soft gear has a small load carrying capacity and low impact resistance, so harmonic transmission is difficult to be widely used. Cycloid transmission mainly uses cycloid gears on the inner wheel. Through the engagement of the cycloid profile on the cycloid gear with the roller pin on the outer wheel, internal engagement for a difference of one tooth can be achieved, but the friction between the cycloid gear and the roller pin can only be reduced by means of providing a sliding sleeve bearing on each of the roller pins. The tooth engagement in all of the above transmissions is a line contact engagement, which results in high tooth flank contact stress, which makes the tooth flank susceptible to wear and separation, and also results in a tooth flank with low load-bearing capacity. Summary of the Invention

[0003] The present application provides an internally engaged transmission mechanism including an outer wheel and an inner wheel. A first number of outer wheel internal teeth are provided on an inner edge of the outer wheel. Each of the outer wheel internal teeth includes an outer wheel internal tooth crest and an outer wheel internal tooth waist symmetrical to the outer wheel internal tooth crest. Each of the outer wheel internal tooth waists includes an engagement portion. A second number of inner wheel external teeth are provided on an outer edge of the inner wheel. Each of the inner wheel external teeth includes an inner wheel external tooth crest and an inner wheel external tooth waist symmetrical to the inner wheel external tooth crest. Each of the inner wheel external tooth waists includes an engagement portion, and the first number is greater than the second number. The inner wheel is disposed inside the outer wheel and rotates eccentrically relative to the outer wheel. The inner wheel and the outer wheel form an internally engaged transmission through engagement between the engagement portion of the inner wheel external tooth waist and the engagement portion of the outer wheel internal tooth waist. The engagement portions of the outer wheel internal tooth waist portions and the engagement portions of the inner wheel external tooth waist portions have the same shape and are overlapping curved surfaces, and the outer wheel internal tooth waist portions and the inner wheel external tooth waist portions are designed such that when the outer wheel and the inner wheel are in an engaged transmission state, at least one of the inner wheel external teeth of the inner wheel external teeth can engage with the outer wheel internal tooth, and for each of the inner wheel external teeth that engages with the outer wheel internal tooth, at least one of the inner wheel external tooth waist portions can form a surface contact engagement with the outer wheel internal tooth waist portion when the inner wheel rotates eccentrically.

[0004] This application provides a novel tooth engagement, namely, surface contact engagement between the inner wheel external teeth and the outer wheel internal teeth. Surface contact engagement is completely different from traditional involute engagement, which can achieve one tooth difference transmission, and the single-stage transmission speed ratio is high. Since the engagement between the inner wheel external teeth and the outer wheel internal teeth is surface contact engagement, the internal engagement transmission mechanism can achieve smooth transmission, low noise, small tooth surface stress, long service life and good impact resistance.

[0005] Other features, advantages, and embodiments of the present application may be described in detail or may become apparent by considering the following specific embodiments, the accompanying drawings, and the claims. Furthermore, it should be understood that the summary and the following specific embodiments are all illustrative and are intended to provide further explanation, but are not intended to limit the scope of protection of the present application. However, the specific embodiments and specific examples merely show preferred embodiments of the present application. Various variations and modifications within the spirit and scope of the present application will be apparent to those skilled in the art through the specific embodiments. [Brief description of the drawings]

[0006] The features and advantages of the present application may be better understood by reading the following detailed description with reference to the accompanying drawings, in which like reference numerals represent like parts throughout the drawings, in which: FIG. 1A is a schematic diagram of a partial cross section of an internal engagement transmission mechanism according to an embodiment of the present application. FIG. 1B is a schematic diagram of an axial cross section of the internal engagement transmission mechanism shown in FIG. 1A. FIG. 2 is a schematic diagram of the engagement between the outer wheel and the inner wheel shown in FIG. 1A. FIG. 3 is a structural schematic diagram of the outer wheel shown in FIG. 2. FIG. 4 is a structural schematic diagram of the inner wheel shown in FIG. 2. FIG. 5A is a schematic diagram of the outer wheel internal teeth and the inner wheel external teeth in a non-meshing state. FIG. 5B-5D show schematic diagrams of the outer wheel internal teeth and the inner wheel external teeth in a partially engaged state during engagement. FIG. 5E shows a schematic diagram of the inner wheel external teeth and the outer wheel internal teeth in a fully meshed state. FIG. 5F-5H show schematic diagrams of the inner wheel external teeth and the outer wheel internal teeth in a partially engaged state during disengagement. FIG. 5I shows a schematic diagram of the outer wheel internal teeth and the inner wheel external teeth in a non-engaged state. FIG. 6A is an enlarged view of a first specific product example of the outer wheel and the inner wheel shown in FIG. 2. Figure 6B is an enlarged view of a second specific product example of the outer wheel and the inner wheel shown in Figure 2. Figure 6C is an enlarged view of a third specific product example of the outer wheel and the inner wheel shown in Figure 2, and Figure 6D is an enlarged view of a fourth specific product example of the outer wheel and the inner wheel shown in Figure 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] Particular embodiments of the present application are described below with reference to the accompanying drawings, which form a part of this description. Although orientation terms such as "left", "right", "inner" and "outer" are used in this application to describe various exemplary structural parts and elements in this application, it should be understood that these terms are used herein merely for ease of description and are determined based on the exemplary orientations shown in the accompanying drawings. Because the embodiments disclosed in this application can be arranged in different orientations, these orientation terms are merely exemplary and should not be considered limiting. In the following accompanying drawings, the same reference numbers are used for the same components and similar reference numbers are used for similar components.

[0008] Ordinal numbers such as "first" and "second" as used in this application are used only for distinction and identification and have no other meaning. Unless otherwise specified, the ordinal numbers do not indicate a particular order or have any particular relevance. For example, the term "first flange" does not, in itself, imply the existence of a "second flange," and the term "second flange" does not, in itself, imply the existence of a "first flange."

[0009] FIG 1A is a schematic partial cross-sectional view of an internal engagement transmission mechanism 100 according to an embodiment of the present application, and FIG 1B is a schematic axial cross-sectional view of the internal engagement transmission mechanism 100 shown in FIG 1A, showing the specific structure of the components in the internal engagement transmission mechanism 100. As shown in FIG 1A-1B, the internal engagement transmission mechanism 100 includes an outer wheel 102, a planetary carrier 101, four inner wheels 121, 122, 123, 124 arranged side by side, and an eccentric shaft 112. The planetary carrier 101 has four inner wheels 121, 122, 123, 124 arranged side by side, and the eccentric shafts 112 are all arranged inside the outer wheel 102.

[0010] Specifically, the eccentric shaft 112 is a hollow shaft having a central axis X. Four eccentric parts 132, 134, 136, 138 are provided on the outer circumference of the eccentric shaft 112. The eccentric part 132 and the eccentric part 138 are a group of eccentric parts having the same eccentric direction, and the eccentric part 134 and the eccentric part 136 are another group of eccentric parts having the same eccentric direction, and the difference between the eccentric directions of the two groups of eccentric parts is 180°. The four inner wheels 121, 122, 123, 124 are respectively sheathed in the four eccentric parts 132, 134, 136, 138 of the eccentric shaft 112 to form four inner wheels arranged in parallel, and the four inner wheels 121, 122, 123, 124 can move parallel to the central axis X.

[0011] The four inner wheels 121, 122, 123, 124 are provided at their outer edges with inner wheel external teeth that engage with the outer wheel internal teeth provided on the inner edge of the outer wheel 102. When the eccentric shaft 112 drives the four inner wheels 121, 122, 123, 124 to move in a translational motion and the outer wheel 102 is fixed, the inner wheel external teeth engage with the outer wheel internal teeth of the outer wheel 102 so that the inner wheels 121, 122, 123, 124 rotate in a translational motion. In this way, the inner wheels 121, 122, 123, 124 can rotate eccentrically (i.e. rotate in a translational motion). In other words, when the inner wheels 121, 122, 123, 124 rotate eccentrically, the central axis (not shown) of the inner wheels 121, 122, 123, 124 can rotate about the central axis X.

[0012] The planetary carrier 101 includes a first flange 104, a second flange 106, a coupling part 109, and a transmission part 108. The four inner wheels 121, 122, 123, 124 are supported by and clamped within the planetary carrier 101. The first flange 104 and the second flange 106 are disposed on two sides of the inner wheels 121, 122, 123, 124, respectively. The first flange 104 and the second flange 106 are rigidly coupled to each other via the coupling part 109, and hold the four inner wheels 121, 122, 123, 124 between the first flange 104 and the second flange 106. The transmission part 108 passes through holes in the four inner wheels 121, 122, 123, 124 to connect the first flange 104 with the second flange 106. The transmission part 108 can transmit the motion of the inner wheels 121, 122, 123, 124 to the first flange 104 and the second flange 106 to rotate the first flange 104 and the second flange 106. It should be noted that since the first flange 104 and the second flange 106 are attached to the outer wheel 102 via bearings, the transmission part 108 drives the first flange 104 and the second flange 106 to rotate about the central axis X, rather than to translate the first flange 104 and the second flange 106.

[0013] The internal engagement transmission mechanism 100 of the present application can achieve the purpose of acceleration or deceleration (i.e., speed reduction or speed increase). When deceleration needs to be achieved, the four inner wheels 121, 122, 123, 124 move at a high speed, and the outer wheel 102 or the planet carrier 101 moves at a low speed. When the outer wheel 102 serves as a torque output component (i.e., connected to a driven component), the planet carrier 101 must be fixed. When the planet carrier 101 serves as a torque output component, the outer wheel 102 must be fixed. When speed increase needs to be achieved, the outer wheel 102 or the planet carrier 101 moves at a low speed, and the four inner wheels 121, 122, 123, 124 move at a high speed as the torque output component. For ease of explanation, an example in which the four inner wheels 121, 122, 123, 124 move at a high speed, the outer wheel 102 is fixed, and the planet carrier 101 moves at a low speed as the torque output component is described below. The power transmission relationship can be essentially described as follows:

[0014] The eccentric shaft 112 of the transmission mechanism 100 is connected to a driving mechanism (not shown). The driving mechanism rotates and drives the eccentric shaft 112. The outer wheel 102 is fixed, and the inner wheels 121, 122, 123, 124 sheathed thereon can be driven to translate and rotate by the rotation of the eccentric shaft 112 due to the engagement relationship between the outer wheel inner teeth of the outer wheel 102 and the inner wheel outer teeth of the inner wheels 121, 122, 123, 124. The transmission part 108 transmits the rotation and torque of the inner wheels 121, 122, 123, 124 to the first flange 104 and the second flange 106, and drives and rotates the first flange 104 and the second flange 106. The first flange 104 and the second flange 106 are connected to a driven device (not shown) to implement speed change and torque output.

[0015] Since the four inner wheels 121, 122, 123, 124 have similar structures, the inner wheel 121 is taken as an example to describe the structural relationship between the inner wheel outer teeth of the inner wheel 121 and the outer wheel inner teeth of the outer wheel 102 as follows.

[0016] FIG. 2 is a schematic diagram of the engagement between the outer wheel 102 and the inner wheel 121 shown in FIG. 1A. As shown in FIG. 2, the outer wheel 102 has a central axis O, which is arranged coaxially with the central axis X of the eccentric shaft 112. The inner wheel 121 is arranged eccentrically in the outer wheel 102. Specifically, the inner wheel 121 has a central axis N1. The central axis N1 is arranged parallel to the central axis O of the outer wheel 102, with a distance e between them. The eccentricity e is greater than zero (see the enlarged view of the dashed box A). The inner edge of the outer wheel 102 is provided with a first number of outer wheel internal teeth 300. The outer edge of the inner wheel 121 is provided with a second number of inner wheel external teeth 400. The first number is greater than the second number.

[0017] Figure 3 is a structural schematic diagram of the outer wheel 102 shown in Figure 2. As shown in Figure 3, the outer wheel 102 is a spur gear. A first number of inner outer wheel teeth 300 are arranged around the inner edge of the outer wheel 102.

[0018] Each outer wheel internal toothing 300 has a similar structure. Two adjacent outer wheel internal toothings 300 are connected to each other via an outer wheel internal toothing base 322. Each of the outer wheel internal teeth 300 includes an outer wheel internal tooth crest 302 and two outer wheel internal tooth waists 314, 316. In a radial cross section of the outer wheel 102, the outer wheel internal tooth crest 302 is a smooth curve or straight line. The two outer wheel internal tooth waists 314, 316 are disposed on two sides of the outer wheel internal tooth crest 302, respectively. The two outer wheel internal tooth waists 314, 316 are disposed symmetrically with respect to the outer wheel internal tooth crest 302, and are completely symmetrical and identical. Specifically, the outer wheel internal tooth waist 314 is located on the left side of the outer wheel internal tooth crest 302, and the outer wheel internal tooth waist 316 is located on the right side of the outer wheel internal tooth crest 302.

[0019] For the left outer wheel internal tooth waist 314, the outer wheel internal tooth waist 314 includes an engagement portion 336 (i.e., the engagement portion 336), a transition portion 332, and a transition portion 334. The engagement portion 336 can form a surface contact with the inner wheel external tooth 400 during engagement. The transition portion 332 is configured so that the engagement portion 336 is connected to the outer wheel internal tooth base 322. The transition portion 334 is configured so that the engagement portion 336 is connected to the outer wheel internal tooth crest 302. In the radial cross section of the outer wheel 102, the transition portion 332 and the transition portion 334 are smooth curves or straight lines, and the engagement portion 336 is a smooth curve, and the curve direction of the engagement portion 336 protrudes toward the outside of the teeth. In other words, the curve direction of the engagement portion 336 protrudes toward the center axis O of the outer wheel 102. The outer wheel inner tooth waist portion 314 is configured such that when the outer wheel 102 engages the inner wheel 121 , the transition portion 332 and the transition portion 334 do not contact the inner wheel 121 .

[0020] Similarly, for the right outer wheel internal tooth waist 316, the outer wheel internal tooth waist 316 includes an engagement portion 346 (i.e., the engagement portion 346), a transition portion 342, and a transition portion 344. The engagement portion 346 can form a surface contact with the inner wheel external tooth 400 during engagement. The transition portion 342 is configured so that the engagement portion 346 is connected to the outer wheel internal tooth base 322. The transition portion 344 is configured so that the engagement portion 346 is connected to the outer wheel internal tooth crest 302. In the radial cross section of the outer wheel 102, the transition portion 342 and the transition portion 344 are smooth curves or straight lines, and the engagement portion 346 is a smooth curve, and the curve direction of the engagement portion 346 protrudes toward the outside of the teeth. In other words, the curve direction of the engagement portion 346 protrudes toward the center axis O of the outer wheel 102. The outer wheel inner tooth waist portion 316 is configured such that when the outer wheel 102 engages the inner wheel 121 , the transition portion 342 and the transition portion 344 do not contact the inner wheel 121 .

[0021] A recess 355 is formed between the adjacent outer wheel internal tooth 300 and the outer wheel internal tooth 300 that receives the inner wheel external tooth 400. More specifically, the recess 355 is formed by the outer wheel internal tooth waist portion 316, the outer wheel internal tooth root portion 322 of the outer wheel internal tooth 300, and the outer wheel internal tooth waist portion 314 of the adjacent outer wheel internal tooth 300. The outer wheel internal tooth waist portion 316 and the outer wheel internal tooth waist portion 314 on two sides of the recess 355 are symmetrical with respect to the center line X of the outer wheel internal tooth. The center line X of the outer wheel internal tooth of each recess 355 passes through the central axis O of the outer wheel 102 and the midpoint of the outer wheel internal tooth base 322 that forms the recess 355. The engagement relationship between the outer wheel internal tooth 300 and the inner wheel external tooth 400 is specifically shown below.

[0022] Figure 4 is a structural schematic diagram of the inner wheel 121 shown in Figure 2. As shown in Figure 4, the inner wheel 121 is also a spur gear. A second number of inner wheel external teeth 400 are provided around the outer edge of the inner wheel 121.

[0023] Each inner wheel external tooth 400 has the same structure. Two adjacent inner wheel external teeth 400 are connected to each other via an inner wheel external tooth base 422. Each of the inner wheel external teeth 400 includes an inner wheel external tooth crest 402 and two inner wheel external tooth waists 414, 416. In a radial cross section of the inner wheel 121, the inner wheel external tooth crest 402 is a smooth curved surface or a straight line. The two inner wheel external tooth waists 414, 416 are respectively disposed on two side surfaces of the inner wheel external tooth crest 402. The two inner wheel external tooth waists 414, 416 are disposed symmetrically with respect to the inner wheel external tooth crest 402 and are completely symmetrical and identical. Specifically, the inner wheel external tooth waist 414 is located on the left side of the inner wheel external tooth crest 402, and the inner wheel external tooth waist 416 is located on the right side of the inner wheel external tooth crest 402.

[0024] For the left inner wheel external tooth waist 414, the inner wheel external tooth waist 414 comprises an engagement portion 436 (i.e., the engagement portion 436), a transition portion 432, and a transition portion 434. The engagement portion 436 can form a surface contact with the outer wheel internal tooth 300 during engagement. The transition portion 432 is configured so that the engagement portion 436 is connected to the inner wheel external tooth base 422. The transition portion 434 is configured so that the engagement portion 436 is connected to the inner wheel external tooth crest 402. In the radial cross section of the outer wheel 102, the transition portion 432 and the transition portion 434 are smooth curves or straight lines, and the engagement portion 436 is a smooth curve, and the direction of the curve of the engagement portion 436 is concave toward the inside of the tooth. In other words, the direction of the curve of the engagement portion 436 is concave toward the center axis N1 of the inner wheel 121. Also, the shape of the curved surface of the engagement portion 436 is the same as and coincides with the shape of the curved surface of the engagement portion 346. In other words, the shape of the curved surface of the engagement portion 436 can be complementary to the shape of the curved surface of the engagement portion 346. The inner wheel outer tooth waist portion 414 is configured such that the transition portion 432 and the transition portion 434 do not contact the outer wheel 102 when the outer wheel 102 engages with the inner wheel 121.

[0025] Similarly, for the right inner wheel external tooth waist 416, the inner wheel external tooth waist 416 includes an engagement portion 446 (i.e., the engagement portion 446), a transition portion 442, and a transition portion 444. The engagement portion 446 can form a surface contact with the outer wheel internal tooth 300 during engagement. The transition portion 442 is configured so that the engagement portion 446 is connected to the inner wheel external tooth base 422. The transition portion 444 is configured so that the engagement portion 446 is connected to the inner wheel external tooth crest 402. In the radial cross section of the outer wheel 102, the transition portion 442 and the transition portion 444 are smooth curves or straight lines, and the engagement portion 446 is a smooth curve, and the direction of the curve of the engagement portion 446 is concave toward the inside of the tooth. In other words, the direction of the curve of the engagement portion 446 is concave toward the center axis N1 of the inner wheel 121. Also, the shape of the curved surface of the engagement portion 446 is the same as and coincides with the shape of the curved surface of the engagement portion 336. In other words, the shape of the curved surface of the engagement portion 446 may be complementary to the shape of the curved surface of the engagement portion 336. The inner wheel external tooth waist portion 416 is configured such that the transition portion 442 and the transition portion 444 do not contact the outer wheel 102 when the outer wheel 102 is engaged with the inner wheel 121. Each inner wheel external tooth 414 and the inner wheel external tooth waist portion 416 of the inner wheel external toothing 400 are symmetrical about the inner wheel external tooth centerline Y. The inner wheel external tooth centerline Y passes through the center axis N1 of the inner wheel 121 and the midpoint of the inner wheel external tooth crest 402.

[0026] In addition, in the radial cross section of the outer wheel 102, the engagement portion 336, the engagement portion 346, the engagement portion 436, and the engagement portion 446 in the present application are not involutes.

[0027] The engagement state between the outer wheel 102 and the inner wheel 121 will be described below with reference to Figures 2 to 4. Specifically, when the inner wheel 121 moves relative to the outer wheel 102, i.e., when the inner wheel 121 rotates (translates and rotates) eccentrically on the outer wheel 102, the engagement state between the inner wheel external toothing 400 of the inner wheel 121 and the outer wheel internal toothing 300 of the outer wheel 102 includes a partial engagement state and a full engagement state. For any inner wheel external toothing 400 of the inner wheel 121, the inner wheel external toothing 400 is in a fully meshed state when the center line X of the outer wheel internal toothing coincides with the center line Y of the inner wheel external toothing, and before and after the fully meshed state, the inner wheel external toothing 400 is in a partially meshed state. The change of any inner wheel external toothing 400 of the inner wheel 121 from a non-engaged state (or released state) to a partially engaged state, a fully engaged state, then a partially engaged state, and a non-engaged state (i.e. released state) will be specifically described with reference to Figures 5A-5I.

[0028] It should also be noted that for the outer wheels 102 and inner wheels 121 in this application, at least one inner wheel external toothing 400 and one outer wheel internal toothing 300 are engaged at any one time. As an example, the outer wheels 102 and inner wheels 121 are designed such that only one inner wheel external toothing 400 engages the outer wheel internal toothing 300 at any one time, and none of the other inner wheel external toothing 400 engages the outer wheel internal toothing 300. As another example, the outer wheels 102 and inner wheels 121 are designed such that three adjacent inner wheel external toothing 400 engage the outer wheel internal toothing 300 at any one time, and none of the other inner wheel external toothing 400 engage the outer wheel internal toothing 300.

[0029] The engagement and disengagement process of the inner wheel 121 and the outer wheel internal toothing 300 changing from a non-engaged state (or non-engaged state) of the inner wheel external toothing 400 to a partially engaged state, a fully engaged state, then a partially engaged state, and then to a non-engaged state (or non-engaged state) is described below with reference to Figures 5A-5I. During the engagement shown in Figures 5A-5I, the inner wheel external toothing 400 and the outer wheel internal toothing 300 form a relative motion. In this embodiment, the outer wheel internal toothing 300 remains fixed, and the inner wheel eccentrically rotates clockwise (as indicated by the arrow in Figure 5A) within the outer wheel 102 (i.e., rotates counterclockwise while moving translationally clockwise). Those skilled in the art will understand that in the process described in Figures 5A-5I, the inner wheel external toothing 400 of the inner wheel 121 gradually contacts the outer wheel internal toothing 300, the contact area gradually increases until it is fully engaged, and then the contact area gradually decreases until the separation can be observed by high-speed photography techniques during the relatively high-speed rotation of the inner wheel external toothing 400 and the outer wheel internal toothing 300. It should be noted that this process is a continuous process. In this application, for ease of explanation, the contact parts in this dynamic continuous process are specifically described at different time periods. Those skilled in the art can understand that Figures 5A-5I are radial cross-sectional views of the inner wheel external toothing 400 and the outer wheel internal toothing 300. In the radial cross-sectional views, the line contact between the inner wheel external toothing 400 and the outer wheel internal toothing 300 is represented by a schematic point contact, and in the radial cross-sectional views, the surface contact between the inner wheel external toothing 400 and the outer wheel internal toothing 300 is represented by a schematic line contact.

[0030] Fig. 5A is a schematic diagram of the outer wheel internal tooth 300 and the inner wheel external tooth 400 in a non-meshing state (disengaged state). From Fig. 5A, it can be seen that the outer wheel internal tooth 300 is not in contact with the inner wheel external tooth 400. More specifically, the engagement portion 436 of the inner wheel external tooth waist portion 414 does not contact the engagement portion 346 of the outer wheel internal tooth waist portion 316, and the engagement portion 446 of the inner wheel external tooth waist portion 416 does not contact the engagement portion 336 of the outer wheel internal tooth waist portion 314.

[0031] 5B-5D show schematic diagrams of the outer wheel internal toothing 300 and the inner wheel external toothing 400 in a partially engaged state during engagement. For the inner wheel external tooth waist 414 on the left side of the inner wheel external toothing 400 and the outer wheel internal tooth waist 316 on the left side of the outer wheel internal toothing 300, in the process from the state shown in FIG. 5A to the state shown in FIG. 5B, as the inner wheel continues to rotate eccentrically clockwise within the outer wheel 102, the distance between the engagement portion 436 and the engagement portion 346 gradually decreases compared to the state shown in FIG. 5A, but the inner wheel external tooth waist 414 has not yet contacted the outer wheel internal tooth waist 316 on the left side of the outer wheel internal toothing 300.

[0032] For the right inner wheel external tooth waist portion 416 of the inner wheel external tooth 400 and the right outer wheel internal tooth waist portion 314 of the outer wheel internal tooth 300, in the process from the state shown in FIG. 5A to the state shown in FIG. 5B, the engagement portion 446 gradually approaches the engagement portion 336, and as shown in FIG. 5B, the engagement portion 446 and the engagement portion 336 begin to form a contact portion. The contact portion may be a line contact or a surface contact. More specifically, the contact portion is located or substantially located at the top of the engagement portion 446 and the top of the engagement portion 336. The protrusion in the radial cross section of the contact portion is shown as a contact region (or contact point) A.

[0033] For the left inner wheel external tooth waist portion 414 of the inner wheel external tooth 400 and the left outer wheel internal tooth waist portion 316 of the outer wheel internal tooth 300, in the process from the state shown in Fig. 5B to the state shown in Fig. 5C, the distance between the engagement portion 436 and the engagement portion 346 continues to gradually decrease, but the engagement portion 436 has not yet contacted the engagement portion 346. Compared with the state shown in Fig. 5B, the engagement portion 436 is closer to the engagement portion 346 in the state shown in Fig. 5C.

[0034] For the inner wheel external tooth waist portion 416 on the right side of the inner wheel external tooth 400 and the outer wheel internal tooth waist portion 314 on the right side of the outer wheel internal tooth 300, the contact area of ​​the contact portion between the engagement portion 446 and the engagement portion 336 gradually increases in the process from the state shown in FIG. 5B to the state shown in FIG. 5C. In the state shown in FIG. 5C, the protrusion of the contact portion between the engagement portion 446 and the engagement portion 336 in the radial cross section is the line segment BC. More specifically, in the process from the state shown in FIG. 5B to the state shown in FIG. 5C, the contact portion between the engagement portion 446 and the engagement portion 336 gradually increases, the contact surface increases, and the line contact changes to surface contact. In addition, such surface contact is not caused by deformation due to the force between the gears, but is achieved by configuring the engagement portion 446 and the engagement portion 336 to have the same shape and be overlapping curved surfaces. During the process of gradually increasing the contact portion (or area) between the engagement portion 446 and the engagement portion 336, the inboard wheel external toothing 400 moves upward relative to the outboard wheel internal toothing 300 such that the engagement portion 446 moves upward relative to the engagement portion 336. At this time, the contact site (or contact point) B is substantially located at the top of the engagement portion 446 and the top of the engagement portion 336, but its position on the engagement portion 336 is closer to the outboard wheel internal toothing base 322 than the previous contact site (or contact point) A shown in FIG.

[0035] For the left inner wheel external tooth waist portion 414 of the inner wheel external tooth 400 and the left outer wheel internal tooth waist portion 316 of the outer wheel internal tooth 300, from the state shown in Fig. 5C to the state shown in Fig. 5D, the engagement portion 436 gradually approaches the engagement portion 346 so that the engagement portions 436 and 346 form a contact portion in the state shown in Fig. 5D. More specifically, the contact portion is located or substantially located at the top of the engagement portion 436 and the top of the engagement portion 346. The protrusions in the radial cross section of the contact portion are shown as contact sites (or contact points) a.

[0036] For the inner wheel external tooth waist 416 on the right side of the inner wheel external tooth 400 and the outer wheel internal tooth waist 314 on the right side of the outer wheel internal tooth 300, the contact area of ​​the contact part between the engagement part 446 and the engagement part 336 continues to gradually increase in the process from the state shown in FIG. 5C to the state shown in FIG. 5D. In the state shown in FIG. 5D, the protrusion of the contact surface of the contact part between the engagement part 446 and the engagement part 336 in its radial cross section is the line segment DE. More specifically, during the process from the state shown in FIG. 5C to the state shown in FIG. 5D, the contact area of ​​the contact part between the engagement part 446 and the engagement part 336 continues to gradually increase, and the inner wheel external tooth 400 continues to move upward relative to the outer wheel internal tooth 300 so that the engagement part 446 moves upward relative to the engagement part 336. At this time, contact site (or contact point) D is substantially located at the top of engagement portion 446 and the top of engagement portion 336, but its location on engagement portion 336 is closer to the outer wheel internal tooth base 322 than the previous contact site (or contact point) B shown in FIG. 5C.

[0037] FIG. 5E shows a schematic diagram of the inner wheel external toothing 400 and the outer wheel internal toothing 300 in a fully engaged state. For the inner wheel external tooth waist 414 on the left side of the inner wheel external toothing 400 and the outer wheel internal tooth waist 316 on the left side of the outer wheel internal toothing 300, from the state shown in FIG. 5D to the state shown in FIG. 5E, as the inner wheel continues to rotate eccentrically clockwise in the outer wheel 102, the contact area of ​​the contact portion between the engagement portion 436 and the engagement portion 346 gradually increases. In the state shown in FIG. 5E, the protrusion of the contact portion between the engagement portion 436 and the engagement portion 346 in its radial cross section is the line segment bc. At this time, the engagement portion 436 coincides with the engagement portion 346. More specifically, during the process from the state shown in FIG. 5D to the state shown in FIG. 5E, the contact portion between the engagement portion 436 and the engagement portion 346 gradually increases, which may be an increase in the contact surface, or may change from line contact to surface contact. Furthermore, such surface contact is not caused by deformation due to forces between the gears, but is achieved by the fact that the engaging portion 436 and the engaging portion 346 have the same shape and are configured to be overlapping curved surfaces. During eccentric rotation of the inner wheel external teeth 400 relative to the outer wheel internal teeth 300, the engaging portion 436 moves upward relative to the engaging portion 346 until the contact area (or contact point) b is located on the top surface of the engaging portion 436 and the engaging portion 346, and the contact area (or contact point) c is located on the bottom of the engaging portion 436 and the engaging portion 346. At this time, the engaging portion 436 and the engaging portion 346 overlap (engage).

[0038] For the inner wheel external tooth waist 416 on the right side of the inner wheel external tooth 400 and the outer wheel internal tooth waist 314 on the right side of the outer wheel internal tooth 300, the contact area of ​​the contact portion between the engagement portion 446 and the engagement portion 336 also continues to gradually increase from the state shown in FIG. 5D to the state shown in FIG. 5E. In the state shown in FIG. 5E, the protrusion of the contact portion between the engagement portion 446 and the engagement portion 336 in the radial cross section is the line segment FG. At this time, the engagement portion 446 coincides with the engagement portion 336. More specifically, in the process from the state shown in FIG. 5D to the state shown in FIG. 5e, the inner wheel external tooth 400 continues to move upward relative to the outer wheel internal tooth 300 until the contact portion (or contact point) F is located at the top of the engagement portion 446 and the engagement portion 336, and the contact portion (or contact point) G is located at the bottom of the engagement portion 446 and the engagement portion 336. At this time, the engagement portion 446 and the engagement portion 336 overlap (engage).

[0039] In this way, in the state shown in FIG. 5E, when the engagement portion 436 and the engagement portion 346 overlap (engage) with each other, and the engagement portion 446 and the engagement portion 336 overlap (engage) with each other, the center line X of the outer wheel internal tooth coincides with the center line Y of the inner wheel external tooth, and the inner wheel external tooth 400 and the outer wheel internal tooth 300 are completely engaged with each other.

[0040] 5F-5H show schematic diagrams of the inner wheel external toothing 400 and the outer wheel internal toothing 300 in a partially engaged state during disengagement. As the inner wheel continues to rotate eccentrically clockwise within the outer wheel 102 between the state shown in FIG. 5E and the state shown in FIG. 5F, the lower portions of the engagement portion 436 and the engagement portion 346 begin to disengage with respect to the inner wheel external tooth waist portion 414 on the left side of the inner wheel external toothing 400 and the outer wheel internal tooth waist portion 316 on the left side of the outer wheel internal toothing 300, thereby gradually reducing the contact area of ​​the contact portion between the inner wheel external tooth waist portion 414 and the outer wheel internal tooth waist portion 316. In the state shown in FIG. 5F, the projection in the radial cross section of the contact portion between the engagement portion 436 and the engagement portion 346 is the line segment de. More specifically, during the process from the state shown in Fig. 5E to the state shown in Fig. 5F, the inner wheel external tooth 400 moves downward relative to the outer wheel internal tooth 300 such that the engagement portion 436 moves downward relative to the engagement portion 346. At this time, the contact site (or contact point) d is located approximately at the top of the engagement portion 436 and the engagement portion 346, but its position on the engagement portion 346 is farther from the outer wheel internal tooth base 322 than the previous contact site (or contact point) b shown in Fig. 5E. The contact site (or contact point) e is located substantially in the middle part of the engagement portion 436 and the engagement portion 346, and is closer to the outer wheel internal tooth base 322 than the previous contact site (or contact point) c shown in Fig. 5E.

[0041] For the inner wheel external tooth waist 416 on the right side of the inner wheel external tooth 400 and the outer wheel internal tooth waist 314 on the right side of the outer wheel internal tooth 300, as the inner wheel continues to rotate eccentrically clockwise in the outer wheel 102 from the state shown in FIG. 5E to the state shown in FIG. 5F, the lower parts of the engagement portion 336 and the engagement portion 446 begin to separate, and the contact area of ​​the contact portion between the engagement portion 336 and the engagement portion 446 gradually decreases. In the state shown in FIG. 5F, the protrusion of the contact portion between the engagement portion 336 and the engagement portion 446 in the radial cross section is the line segment HI. More specifically, during the process from the state shown in FIG. 5E to the state shown in FIG. 5F, the inner wheel external tooth 400 moves downward relative to the outer wheel internal tooth 300 so that the engagement portion 446 moves downward relative to the engagement portion 336. At this time, contact site (or contact point) H is approximately located on the top of engagement portion 336 and engagement portion 446, but its location on engagement portion 446 is farther from the outer wheel internal toothing base 322 than the previous contact site (or contact point) G shown in Figure 5E. Contact site (or contact point) I is substantially located on the bottom of engagement portion 336 and engagement portion 446, and is closer to the outer wheel internal toothing base 322 than the previous contact site (or contact point) G shown in Figure 5E.

[0042] It should also be noted that as the inner wheel continues to rotate eccentrically clockwise within the outer wheel 102, the disengagement between the engagement portion 436 and the engagement portion 346 is greater than the disengagement between the engagement portion 336 and the engagement portion 446. That is, the contact area between the engagement portion 436 and the engagement portion 346 is less than the contact area between the engagement portion 336 and the engagement portion 446. That is, the contact site (or contact point) e is closer to the outer wheel internal toothing base 322 than the contact site (or contact point) I.

[0043] For the inner wheel external tooth waist 414 on the left side of the inner wheel external toothing 400 and the outer wheel internal tooth waist 316 on the left side of the outer wheel internal toothing 300, in the process from the state shown in Fig. 5F to the state shown in Fig. 5G, as the inner wheel continues to rotate eccentrically clockwise in the outer wheel 102, the lower part of the engagement part 436 and the engagement part 346 continue to disengage so that the contact area of ​​the contact part between the engagement part 436 and the engagement part 346 gradually decreases until the abutment part is substantially located on the upper surface of the engagement part 436 and the upper surface of the engagement part 346, as shown in Fig. 5G. The protrusion of the contact part (or contact line) in the radial cross section is shown as the contact site (or contact point) f.

[0044] For the inner wheel external tooth waist 416 on the right side of the inner wheel external tooth 400 and the outer wheel internal tooth waist 314 on the right side of the outer wheel internal tooth 300, in the process from the state shown in FIG. 5F to the state shown in FIG. 5G, when the inner wheel continues to rotate eccentrically clockwise on the outer wheel 102, the lower parts of the engagement portion 336 and the engagement portion 446 continue to separate so that the contact area of ​​the contact portion between the engagement portion 336 and the engagement portion 446 continues to gradually decrease. In the state shown in FIG. 5G, the protrusion of the contact portion between the engagement portion 336 and the engagement portion 446 in its radial cross section is the line segment JK. More specifically, during the process from the state shown in FIG. 5F to the state shown in FIG. 5G, the inner wheel external tooth 400 moves downward relative to the outer wheel internal tooth 300 so that the engagement portion 446 moves downward relative to the engagement portion 336. At this time, contact site (or contact point) J is located substantially at the top of engagement portion 336 and engagement portion 446, but its location on engagement portion 336 is farther from the outer wheel internal toothing base 322 than previous contact site (or contact point) H shown in Figure 5F. Contact site (or contact point) K is located substantially at the bottom of engagement portion 336 and engagement portion 446, but its location on engagement portion 336 is closer to the outer wheel internal toothing base 322 than previous contact site (or contact point) I shown in Figure 5F.

[0045] For the left inner wheel external tooth waist portion 414 of the inner wheel external toothing 400 and the left outer wheel internal tooth waist portion 316 of the outer wheel internal toothing 300, as the inner wheel continues to rotate eccentrically clockwise on the outer wheel 102 from the state shown in Figure 5G to the state shown in Figure 5H, the lower parts of the engagement portion 436 and the engagement portion 346 continue to disengage until the engagement portion 436 and the engagement portion 346 no longer contact each other, as shown in Figure 5H.

[0046] For the right inner wheel external tooth waist 416 of the inner wheel external toothing 400 and the right outer wheel internal tooth waist 314 of the outer wheel internal toothing 300, as the inner wheel continues to rotate eccentrically clockwise on the outer wheel 102 in the process shown in Figure 5G to the state shown in Figure 5H, the lower parts of the engagement portion 336 and the engagement portion 446 continue to disengage. More specifically, the contact portion is located substantially at the upper part of the engagement portion 336 and the engagement portion 446. The protrusion of the contact point in the radial cross section is shown as contact point (or contact point) L.

[0047] FIG. 5I shows a schematic diagram of the outer wheel internal toothing 300 and the inner wheel external toothing 400 in a non-engaged state (i.e., disengaged from each other). For the inner wheel external tooth waist 414 on the left side of the inner wheel external toothing 400 and the outer wheel internal tooth waist 316 on the left side of the outer wheel internal toothing 300, the engagement portion 436 is no longer in contact with the engagement portion 346 as the inner wheel continues to rotate eccentrically clockwise in the outer wheel 102 from the state shown in FIG. 5H to the state shown in FIG. 5I, the engagement portion 336 and the engagement portion 446 are completely disengaged (not in contact) as the inner wheel continues to rotate eccentrically clockwise in the outer wheel 102 for the inner wheel external tooth waist 416 on the right side of the inner wheel external toothing 400 and the outer wheel internal tooth waist 314 on the right side of the outer wheel internal toothing 300.

[0048] In this way, as can be seen from the above engagement process, in the process from the start of engagement to the fully engaged state, in the radial cross section, the contact area of ​​both the protrusions of the contact portion between the left inner wheel external tooth waist portion 414 of the inner wheel external tooth 400 and the left outer wheel internal tooth waist portion 316 of the outer wheel internal tooth waist portion 300, and the contact portion between the right inner wheel external tooth waist portion 416 of the inner wheel external tooth 400 and the right outer wheel internal tooth waist portion 314 of the outer wheel internal tooth 300 gradually increases until it reaches a maximum value at the fully engaged state (see Figures 5A-5E). During the process from the fully engaged state to disengagement, in the radial cross section, the contact area of ​​both protruding portions, the contact portion between the inner wheel external tooth waist portion 414 on the left side of the inner wheel external tooth 400 and the outer wheel internal tooth waist portion 316 on the left side of the outer wheel internal tooth 300, and the contact portion between the inner wheel external tooth waist portion 416 on the right side of the inner wheel external tooth 400 and the outer wheel internal tooth waist portion 314 on the right side of the outer wheel internal tooth 300, gradually decreases from the maximum value (see Figures 5E-5I).

[0049] Furthermore, during the process from the start of engagement to the fully engaged state and then to the fully disengaged state, the contact areas of the inner wheel external tooth waist portion 414 on the left side of the inner wheel external tooth 400, the outer wheel internal tooth waist portion 316 on the left side of the outer wheel internal tooth 300, the inner wheel external tooth waist portion 416 on the right side of the inner wheel external tooth 400, and the outer wheel internal tooth waist portion 314 on the right side of the outer wheel internal tooth 300 are all configured so that they gradually increase and then gradually decrease.

[0050] In the present application, surface contact means that when the inner wheel external toothing 400 and the outer wheel internal toothing 300 are fully engaged, in the radial cross section of the inner wheel external toothing 400 and the outer wheel internal toothing 300, the length of the contact line between the inner wheel external tooth waist portion 414 and the outer wheel internal tooth waist portion 316 is greater than at least 1% of the length of the inner wheel external tooth waist portion 414, and the length of the contact line between the inner wheel external tooth waist portion 416 and the outer wheel internal tooth waist portion 314 is greater than at least 1% of the length of the inner wheel external tooth waist portion 416. In other words, the length of the engagement portion 436 and the engagement portion 446 of the inner wheel 121 is greater than at least 1% of the length of the inner wheel external tooth waist portion 414 and the inner wheel external tooth waist portion 416, respectively.

[0051] 5A-5I only show a particular positional relationship between one inner wheel external toothing 400 and one outer wheel internal toothing 300 from disengaged to fully engaged to disengaged. However, one skilled in the art will understand that as the inner wheel 121 eccentrically rotates 360° within the outer wheel 102, the inner wheel external toothing 400 in the inner wheel 121 can sequentially engage with the outer wheel internal toothing 300 in the outer wheel 102, and when any of the inner wheel external toothing 400 in the inner wheel 121 engages with the outer wheel internal toothing 300, the above-mentioned process of engagement occurs.

[0052] In the conventional internal engagement transmission mechanism, the inner wheel external teeth and the outer wheel internal teeth usually use the engagement between the cycloid and the roller pin or between the involute, so that a line contact engagement is formed between the inner wheel external teeth and the outer wheel internal teeth. The contact area of ​​the line contact engagement is very small and almost zero. When the inner wheel external teeth and the outer wheel internal teeth are in the transmission state, the area of ​​the line engagement is almost zero, so the tooth surface stress generated when the inner wheel external teeth engage with the outer wheel internal teeth is very large. The extremely large stress causes the gear surface to peel off, so that the service life of the inner wheel external teeth and the outer wheel internal teeth is short, and the transmission of the internal meshing transmission mechanism is not stable enough.

[0053] Surface engagement can be formed between the inner wheel external teeth and the outer wheel internal teeth in the internal engagement transmission mechanism 100 in the present application. The contact area of ​​the surface engagement is significantly greater than that of the line engagement in the conventional internal engagement transmission mechanism. As an example, in the radial cross section of the inner wheel external teeth and the outer wheel internal teeth, the length of the contact line of the surface engagement of the internal engagement transmission mechanism 100 in the present application is 0.1 mm. If the contact line of the line engagement in the conventional internal engagement transmission mechanism has a certain length, which is set to, for example, 0.001 mm in stress calculation (in stress calculation, the contact area of ​​the tooth surface cannot be set to zero, otherwise the tooth surface stress will be infinitely large), the line contact length in the present application will be 100 times the contact length of the line engagement. In this way, the stress between the inner wheel external teeth and the outer wheel internal teeth of the surface engagement in the present application is 0.01 times the stress between the inner wheel external teeth and the outer wheel internal teeth of the conventional line engagement. This can greatly reduce the stress between the inner wheel external teeth and the outer wheel internal teeth, and prevent the wear, damage, etc. of the gears. This can also reduce the heat generated by the stress of the inner wheel external teeth and the outer wheel internal teeth, so that the internal engagement transmission mechanism 100 has better stability and longer service life. As an example, even after the reducer manufactured by the internal engagement transmission mechanism in this application operates at a speed of 1500 rpm at rated load for 1000 hours, the lubricating oil in the reducer maintains its original color, while the lubricating oil in the reducer turns black after the reducer of the conventional internal engagement transmission mechanism operates under the same operating conditions. This shows that compared with the engagement transmission between the cycloid and the roller pin or between the involute in the prior art, the surface contact engagement between the inner wheel external teeth and the outer wheel internal teeth in this application has small tooth surface stress, and the generated heat and wear are reduced.

[0054] In addition, the feature of "overlapping" in the description of "the engaging portion of the outer wheel internal tooth waist portion and the engaging portion of the inner wheel external tooth waist portion are overlapping curved surfaces of the same shape" in this application includes both complete overlap (i.e., the engaging portions overlap 100%) and general (general) overlap. The difference between general overlap and complete overlap is that general overlap occurs due to precision errors caused by manufacturing, processing, assembly, etc. Those skilled in the art will understand that such precision errors caused by manufacturing, processing, assembly, etc. do not affect the surface contact formed between the engaging portions, and such precision errors do not affect the technical effect of the internal engagement transmission mechanism in the above application.

[0055] Figure 6A is an enlarged view of a first specific product example of the outer wheel 102 and the inner wheel 121 shown in Figure 2, Figure 6B is an enlarged view of a second specific product example of the outer wheel 102 and the inner wheel 121 shown in Figure 2, Figure 6C is an enlarged view of a third specific product example of the outer wheel 102 and the inner wheel 121 shown in Figure 2, and Figure 6D is an enlarged view of a fourth specific product example of the outer wheel 102 and the inner wheel 121 shown in Figure 2. In the figures, (a) shows the fitting state of the outer wheel 102 and the inner wheel 121, (b) shows the outer wheel 102, (c) shows the inner wheel 121, and (d) shows an enlarged radial cross-sectional view of the engagement portion 336 of the outer wheel 102.

[0056] In Fig. 6A, (a)-(c) show a first embodiment of the outer wheel 102 and the inner wheel 121 shown in Fig. 2, enlarged at a scale of 1:30. In the first embodiment, the number of teeth of the outer wheel 102 is 36, the number of teeth of the inner wheel 121 is 35, and the difference in the number of teeth of the outer wheel 102 and the inner wheel 121 is 1 (1 tooth difference). The eccentricity e between the outer wheel 102 and the inner wheel 121 is 2 mm. The elastic modulus of the teeth is 2.4 mm. The tooth tip height of the inner wheel external toothing 400 and the outer wheel internal toothing 300 is 2.4 mm. (d) of the figure shows a particular curve of the engagement part 336 of the outer wheel 102 in a radial section drawn at a scale of 1:1500.

[0057] In Fig. 6B (a)-(c) a second embodiment of the outer wheel 102 and the inner wheel 121 shown in Fig. 2 is shown enlarged at a scale of 1:30. In the second embodiment, the number of teeth of the outer wheel 102 is 60, the number of teeth of the inner wheel 121 is 59, and the difference in the number of teeth of the outer wheel 102 and the inner wheel 121 is 1 (1 tooth difference). The eccentricity e between the outer wheel 102 and the inner wheel 121 is 1.2 mm. The elastic modulus of the teeth is 1.4 mm. The tooth tip height of the inner wheel external toothing 400 and the outer wheel internal toothing 300 is 1.5 mm. Fig. 6(d) shows a particular curve of the engagement part 336 of the outer wheel 102 in a radial section drawn at a scale of 1:2400.

[0058] In Fig. 6C, (a)-(c) show a third embodiment of the outer wheel 102 and the inner wheel 121 shown in Fig. 2, enlarged at a scale of 1:30. In the third embodiment, the number of teeth of the outer wheel 102 is 100, the number of teeth of the inner wheel 121 is 98, and the difference in the number of teeth between the outer wheel 102 and the inner wheel 121 is 2 (2 teeth difference). The eccentricity e between the outer wheel 102 and the inner wheel 121 is 2.0 mm. The elastic modulus of the teeth is 2.0 mm. The tooth tip height of the inner wheel external toothing 400 and the outer wheel internal toothing 300 is 2.0 mm. (d) of the figure shows a particular curve of the engagement portion 336 of the outer wheel 102 in a radial section drawn at a scale of 1:3000.

[0059] In Fig. 6D (a)-(c) a fourth embodiment of the outer wheel 102 and the inner wheel 121 shown in Fig. 2 is shown enlarged at a scale of 1:50. In the fourth embodiment, the number of teeth of the outer wheel 102 is 72, the number of teeth of the inner wheel 121 is 69, and the difference in the number of teeth of the outer wheel 102 and the inner wheel 121 is 3 (3 teeth difference). The eccentricity e between the outer wheel 102 and the inner wheel 121 is 2.3 mm. The elastic modulus of the teeth is 1.0 mm. The tooth tip height of the inner wheel external toothing 400 and the outer wheel internal toothing 300 is 0.6 mm. Fig. (d) shows a particular curve of the engagement part 336 of the outer wheel 102 in a radial section drawn at a scale of 1:4000.

[0060] Although only certain features of the present application have been illustrated and described herein, various improvements and changes can be made by those skilled in the art. It is therefore to be understood that the appended claims are intended to cover all such improvements and changes that fall within the true spirit and scope of the present application.

Claims

1. A transmission mechanism (100), An outer wheel (102) and an inner wheel, a first number of inner outer wheel teeth (300) are provided on an inner edge of the outer wheel (102); Each of the outer wheel internal teeth (300) comprises an outer wheel internal tooth crest (302) and an outer wheel internal tooth waist portion (302) symmetrical with respect to the outer wheel internal tooth crest (302), Each of the outer wheel tooth waist portions includes an engagement portion; a second number of inner wheel external teeth (400) are provided on an outer edge of said inner wheel; Each of said inner wheel external teeth (400) comprises an inner wheel external tooth crest (402) and an inner wheel external tooth waist portion symmetrical about said inner wheel external tooth crest (402), each of the inner wheel external tooth waist portions includes an engagement portion; the first number is greater than the second number; The inner wheel is disposed inside the outer wheel (102) and rotates eccentrically relative to the outer wheel (102), and the inner wheel and the outer wheel (102) engage with each other via an engagement portion of the inner wheel outer tooth waist portion and an engagement portion of the outer wheel inner tooth waist portion, the engaging portion of the outer wheel internal tooth waist portion and the engaging portion of the inner wheel external tooth waist portion are overlapping curved surfaces, the outer wheel internal tooth waist portion and the inner wheel external tooth waist portion are designed such that when the outer wheel (102) and the inner wheel are in an engaged state for transmitting power, at least one inner wheel external tooth (400) in the inner wheel external toothing (400) can engage with the outer wheel internal toothing (300), and for each of the inner wheel external teeth (400) that engage with the outer wheel internal toothing (300), at least one of the inner wheel external tooth waist portions can form a surface contact engagement with the outer wheel internal tooth waist portion when the inner wheel rotates eccentrically, The outer wheel internal tooth waist portion and the inner wheel external tooth waist portion are designed such that, for each of the inner wheel external teeth (400) engaged with the outer wheel internal tooth (300), both of the two inner wheel external tooth waist portions of the inner wheel external tooth (400) are engaged with the outer wheel internal tooth waist portion of the outer wheel internal tooth (300), and the engagement is surface contact engagement, in a transmission mechanism (100).

2. 2. The transmission mechanism (100) of claim 1, wherein the contact area formed by the inner wheel external tooth waist and the outer wheel internal tooth waist when the inner wheel rotates eccentrically is variable.

3. 3. The transmission mechanism (100) of claim 2, wherein as the inner wheel rotates eccentrically, a contact area formed by the inner wheel external tooth waist portion contacting the outer wheel internal tooth waist portion gradually increases and then gradually decreases to an extent that the inner wheel external tooth waist portion and the outer wheel internal tooth waist portion separate from each other.

4. the outer wheel internal tooth waist portion and the inner wheel external tooth waist portion are designed such that the engagement portion of the inner wheel external tooth waist portion and the engagement portion of the outer wheel internal tooth waist portion are in a partial engagement state and a full engagement state with respect to each of the inner wheel external teeth (400) that engage with the outer wheel internal teeth (300); When the engagement portion of the inner wheel external tooth waist portion and the engagement portion of the outer wheel internal tooth waist portion are in a partially engaged state, a part of the engagement portion of the inner wheel external tooth waist portion can form a surface contact engagement with a part of the engagement portion of the outer wheel internal tooth waist portion, When the engagement portion of the inner wheel external tooth waist portion and the engagement portion of the outer wheel internal tooth waist portion are in a fully engaged state, the engagement portion of the outer wheel internal tooth waist portion can have a maximum contact area with the engagement portion of the inner wheel external tooth waist portion; 2. The transmission mechanism (100) of claim 1, wherein the inner wheel external tooth waist and the outer wheel internal tooth waist are in a partially engaged state when the engaging portion of the inner wheel external tooth waist and the engaging portion of the outer wheel internal tooth waist begin to engage or disengage.

5. 5. The transmission mechanism (100) of claim 4, wherein as the engagement portion of the inner wheel external tooth waist portion and the engagement portion of the outer wheel internal tooth waist portion approach a fully engaged state, the contact area between the engagement portion of the inner wheel external tooth waist portion and the engagement portion of the outer wheel internal tooth waist portion gradually increases, and when the engagement portion of the inner wheel external tooth waist portion and the engagement portion of the outer wheel internal tooth waist portion disengage from the fully engaged state, the contact area between the engagement portion of the inner wheel external tooth waist portion and the engagement portion of the outer wheel internal tooth waist portion gradually decreases.

6. the engaging portions of the inner wheel external tooth waist portion on the two sides of the apex (402) of the inner wheel external tooth are arranged symmetrically with respect to the center line (Y) of the inner wheel external tooth, 6. The transmission mechanism (100) according to claim 5, wherein the engaging portion of the outer wheel internal tooth waist of the outer wheel internal tooth (300) and the engaging portion of the outer wheel internal tooth waist of the adjacent outer wheel internal tooth (300) are arranged symmetrically with respect to a center line (X) of the outer wheel internal tooth, and when the inner wheel engages with the outer wheel (102) and the center line (Y) of the inner wheel external tooth coincides with the center line (X) of the outer wheel internal tooth, the inner wheel external tooth (400) and the outer wheel internal tooth (300) are in a fully engaged state.

7. 6. The transmission mechanism (100) of claim 5, wherein the outer wheel internal toothing (300) and the inner wheel external toothing (400) are all spur gears, and in a radial cross section of the inner wheel and the outer wheel (102), the outer wheel internal tooth waist portion and the inner wheel external tooth waist portion are continuous and smooth curves, the direction of the curve of the engagement portion of the outer wheel internal tooth waist portion protrudes toward the outside of the outer wheel internal toothing (300), and the direction of the curve of the engagement portion of the inner wheel external tooth waist recess protrudes toward the inside of the inner wheel external toothing (400).

8. The transmission mechanism (100) of claim 1, wherein the difference between said first number and said second number is one.

9. 7. The transmission mechanism (100) of claim 6, wherein, when the engagement portion of the inner wheel external tooth waist portion and the engagement portion of the outer wheel internal tooth waist portion are in a fully engaged state, in a cross section of the outer wheel internal tooth (300) and the inner wheel external tooth (400), the length of a contact line between the engagement portion of the inner wheel external tooth waist portion and the engagement portion of the outer wheel internal tooth waist portion is greater than 1% of the length of the inner wheel external tooth waist portion.

10. 8. The transmission mechanism (100) of claim 7, wherein in a radial cross section of the inner wheel and the outer wheel (102), a curve of an engagement portion between an inner wheel external tooth waist portion and an outer wheel internal tooth waist portion is not an involute.

Images