Differential type small-tooth-difference speed reducer

Abstract

The utility model discloses a differential type small-tooth-difference speed reducer, and belongs to the field of machinery. The structure comprises a gear ring or a sun gear, a cam and a planetary gear, firstly, a gear ring A and a planetary gear C as well as a gear ring B and a planetary gear D are two pairs of independent planetary motion combinations; when the constraint gear ring A is static, the planetary gear C is arranged in the gear ring, so that the number of teeth is smaller than that of the gear ring A to cause a speed difference value, and the rotating speed relation between a high-speed shaft and a low-speed shaft is that the directions of two rotating speeds are opposite, so that the superposed rotating speed is the difference value of omega1-omega2; the value can be a positive value, a negative value or even zero; as a result, the reduction ratio of forward transmission, reverse transmission and infinity is larger, and the relation between the reduction ratio and the tooth height is not large. The device can be widely used in the machinery industry.

Description

Technical Field

[0001] The present invention belongs to the field of mechanical technology. Specifically speaking, it is an improved harmonic gear reducer with a small tooth difference, which is a gear reduction structure that realizes a high reduction ratio under a large tooth type through differential motion. Background Art

[0002] Brief Introduction to Harmonic Reducer Technology:

[0003] The harmonic reducer originated abroad in the 1950s and began to be developed in China in the 1960s and 1970s. There are already many manufacturers specializing in production and forming a series. It is widely used in industries such as electronics, aerospace, and robotics. Due to its unique advantages, its application in the chemical industry is also gradually increasing. In fact, this technology is an evolution based on the original technology of small tooth difference in the 1920s. English: harmonic gear drive. Definition: It mainly consists of four basic components: a wave generator, a flexible gear, a flexible bearing, and a rigid gear. The harmonic drive reducer is a gear drive that relies on the wave generator assembled with a flexible bearing to cause the flexible gear to generate controllable elastic deformation and mesh with the rigid gear to transmit motion and power. Applied disciplines: Mechanical Engineering (first-level discipline); Transmission (second-level discipline); Gear Transmission (third-level discipline). The harmonic gear drive reducer is a new type of reducer developed based on the principle of planetary gear drive. Harmonic gear drive (abbreviation: harmonic drive).

[0004] The wave generator H is a rod-shaped component with rolling bearings installed at both ends to form rollers, which are tightly pressed against the inner wall of the flexible gear 1. The flexible gear is a thin-walled gear that can generate large elastic deformation, and the inner hole diameter is slightly smaller than the major axis of the wave generator. The wave generator is the component that causes the flexible gear to generate controllable elastic deformation. When the wave generator is installed in the flexible gear, it forces the cross-section of the flexible gear to change from the original circular shape to an elliptical shape. The teeth near both ends of the major axis are fully meshed with the teeth of the rigid gear, while the teeth near both ends of the minor axis are completely disengaged from the rigid gear. The teeth in other sections of the circumference are in a transitional state of meshing and disengagement. When the wave generator rotates continuously in the direction shown in the figure, the deformation of the flexible gear continuously changes, causing the meshing state between the flexible gear and the rigid gear to also continuously change, from meshing in, meshing, meshing out, disengaging, and then meshing in again... repeating in a cycle, thereby realizing the slow rotation of the flexible gear relative to the rigid gear in the opposite direction of the wave generator H. During operation, the rigid gear is fixed, the wave generator is driven by the motor to rotate, and the flexible gear serves as the driven wheel to output rotation and drive the load to move. During the transmission process, the number of cycles of deformation of a certain point on the flexible gear when the wave generator rotates one week is called the wave number, denoted by n. Commonly used are two types: double-wave and triple-wave. The stress of the flexible gear in double-wave transmission is smaller, the structure is relatively simple, and it is easy to obtain a large transmission ratio. Therefore, it is the most widely used type.

[0005] Basic Characteristics:

[0006] * High load-carrying capacity In harmonic drives, the tooth-to-tooth meshing is a surface contact. Coupled with a relatively large number of simultaneously meshing teeth (contact ratio), the load per unit area is small, and the load-carrying capacity is higher than that of other drive forms.

[0007] * Large transmission ratio The transmission ratio of a single-stage harmonic gear drive can reach i = 70 - 500.

[0008] * Small size and light weight.

[0009] * High transmission efficiency and long service life.

[0010] * Smooth transmission, no impact, no noise, and high motion accuracy.

[0011] * Since the flexspline bears relatively large alternating loads, higher requirements are imposed on the fatigue strength, machining, and heat treatment of the flexspline material, and the process is complex.

[0012] Brief introduction to the origin technology of small tooth difference:

[0013] In a small tooth difference planetary gear drive, the tooth difference is usually 1 - 4. The external gear is mounted on the input shaft of the reducer through bearings and an eccentric sleeve. To balance part of the inertial force and improve the load-carrying capacity, usually two external gears are used, and there are two eccentrics on the eccentric sleeve that are 180° apart. The internal gear mostly remains stationary. The output mechanism transmits the rotation of the external gear to the output shaft through pin shafts and keeps its angular velocity unchanged. Commonly used output mechanisms include pin shaft type and floating disk type, etc.

[0014] Structure and principle:

[0015] The small tooth difference planetary drive is an evolved form of the ordinary planetary drive. Its structure is simpler than that of the ordinary planetary drive and includes an internal gear ring, a planetary carrier, planetary gears, and a disk-shaped output shaft. In this structure, the planetary carrier is the driving part, and the planetary gears are the driven parts, which is the opposite of the ordinary planetary drive.

[0016] The structure of the double universal coupling not only has a large axial dimension but also cannot be used in the case of multiple planetary gears and is now basically not used. The most widely used is the pin hole type disk-shaped output mechanism. A number of pin holes are evenly distributed along the circumference on the web of the planetary gear, and the same number of cylindrical pins are evenly distributed at the corresponding positions on the disk of the output shaft. The pins are inserted into the pin holes of the planetary gear. The center distance between the internal gear ring and the planetary gear (i.e., the eccentricity of the planetary carrier) must be equal to the difference between the radius of the pin hole and the radius of the pin shaft, so as to ensure that the pin hole and the pin shaft always remain tangent, and the planetary gear can push the disk-shaped output shaft to rotate at the same speed and in the same direction. At this time, the centers of the internal gear ring, the planetary gear, the pin hole, and the pin shaft just form a parallelogram.

[0017] Applications of small tooth difference planetary drives:

[0018] Planetary transmissions are widely used in planetary speed reducers for power transmission, and they have the advantages of compact size design, light weight, and large transmission power. The few teeth difference planetary transmission is a special type of planetary transmission. The motion of the planetary gear is a compound motion of self-rotation and revolution, and the calculation of its transmission ratio is relatively complex. It is divided into single-stage transmission and multi-stage transmission: The transmission ratio generally adopted for the involute few teeth difference single-stage transmission is above 20 to 100, and the efficiency is 0.8 to 0.9. Its gears can be machined by general gear machine tools. If the number of teeth of the external gear is Z0 and the number of teeth of the internal gear is Zb, then when the internal gear is fixed, the transmission ratio ib of the input shaft and the output shaft is -Z0 / (Zb - Z0); when the output shaft (F) is stationary, the transmission ratio iF of the input shaft and the internal gear is Zb / (Zb - Z0). The smaller the tooth difference between the internal and external gears, the larger the transmission ratio obtained for each stage of transmission. However, when the tooth difference is reduced to a certain extent, for example, when using standard involute gears with a pressure angle of 20°, when the number of teeth of the internal gear is less than 180 and the tooth difference is less than 5 to 7, tooth profile overlapping interference will occur in the internal meshing gears. The solution is to adopt stub teeth and perform appropriate modification.

[0019] Main disadvantages of harmonic reducer technology:

[0020] * The flexspline deforms periodically, thus generating alternating stress, making it prone to fatigue failure.

[0021] * The moment of inertia and starting torque are large, and it is not suitable for low-power tracking transmissions.

[0022] * It cannot be used in occasions where the transmission speed ratio is less than 35.

[0023] * For harmonic transmissions using a roller wave generator (free deformation wave), its instantaneous transmission ratio is not a constant.

[0024] * The heat dissipation condition is poor.

[0025] Main disadvantages of few teeth difference reducer technology:

[0026] * The torque it can bear decreases sharply with the reduction of tooth height, making it prone to fatigue failure.

[0027] * The speed ratio change is not as large as that of harmonic speed reducers.

[0028] * The mechanical structure is relatively complex and the cost is relatively high. [Summary of the Invention]

[0029] The object of the present invention: To simplify the structure of a few teeth difference reducer with a large reduction ratio and create a reducer that has advantages in terms of strength, volume, and reduction ratio.

[0030] The characteristics of the present invention: Compact structure, high transmission efficiency and transmission frequency, and long service life.

[0031] The key technology of the present invention: An eccentric circular cam is adopted to generate the first harmonic wave, and to drive a double-sided planetary gear to perform associated planetary motion, thereby obtaining the deceleration of the mechanism.

[0032] Specific invention content: The structure of a differential planetary gear reducer with few teeth difference includes: a ring gear or a sun gear, a cam, and a planetary gear; Assembly relationship: When the internal ring gear is used in cooperation with the planetary gear, the ring gear A and the ring gear B are coaxial (the same ring gear axis center and ring gear axis), and are respectively connected to the high-speed shaft and the low-speed shaft of the reducer; The planetary gear C and the planetary gear D are coaxial (the same planetary axis center and planetary axis), are installed on the same rotating disk, and are respectively tangent to the ring gear A and the ring gear B as planetary gears. See the joint between the ring gear A and the planetary gear C and the joint between the ring gear B and the planetary gear D; The ring gear axis is parallel to the planetary axis and has a spacing; The cam part of the cam is a disk perpendicular to the above-mentioned axis, and the axis passes through the center of the circle. The disk restricts the free rotation of the two fixedly installed planetary gears C and D processed on the same axis through bearings; After the disk cam part of the cam is eccentrically (rigidly) installed on the high-speed shaft, rotating the high-speed shaft can drive the revolution of the cam; So that the planetary axis revolves parallel to the ring gear axis and the spacing remains unchanged; Multiple housing parts play a role in supporting and guiding the rotating shaft.

[0033] Working principle: First, the combination of the ring gear A and the planetary gear C, and the ring gear B and the planetary gear D is a combination of two pairs of independent planetary motions; When the ring gear A is restricted to be stationary, since the planetary gear C is inside the ring gear, the number of teeth is less than that of the ring gear A; Therefore, the revolution speed of the cam driven by rotating the high-speed shaft is greater than the rotation speed of the planetary gear C, manifested as: the angular displacement of the planetary gear C is less than the angular displacement of the cam; Similarly, the angular displacement of the planetary gear D is also less than the angular displacement of the cam, that is, the angular displacement of the cam is greater than the angular displacement of the planetary gear D; Since the difference in the number of teeth between the planetary gear and the ring gear is small (the difference in the number of teeth is not large), the difference in speed is not large either. Therefore, the rotational speed relationship between the high-speed shaft and the low-speed shaft: the rotational speed ω1 between the ring gear A and the planetary gear C, plus the rotational speed ω2 between the ring gear B and the planetary gear D; Since the directions of the two rotational speeds are opposite, the superimposed rotational speed is their difference (ω1 - ω2).

[0034] Independent adjustment parameters: The relationship between the pitch circles, the number of teeth, etc. between the ring gear A and the planetary gear C, and the ring gear B and the planetary gear D, and the difference in angular velocity (ω1 - ω2) can be positive, negative, or even zero; This means that forward transmission, reverse transmission, a larger reduction ratio, or even infinity (the relative rotational angular velocity ω of the few teeth difference = (number of teeth difference / number of teeth) x rotational speed x 2π), and the reduction ratio is equal to ω1 / ω2.

[0035] When the sun gear is used in combination with the planetary gear, the planetary gear at this time is an internal gear (ring gear shape), and it is still the superposition of the independent transmissions of two sets of sun gears and planetary gears; it is also to concentrically fix two planetary gears on a turntable and drive its revolution with a cam; it is also to connect the high-speed shaft and the low-speed shaft to their respective sun gears; the speed relationship and characteristics are exactly the same as above.

[0036] Furthermore: This speed reducer can use the planetary gear as the high-speed shaft and the low-speed shaft of the output, and coaxially install the ring gear or the sun gear on the same rotating disk; in this way, the relative meshing and motion relationship between the two sets of planetary gears and sun gears are the same; the superposition relationship of their angular velocities is the same as above.

[0037] The technical progress of the present invention: Compared with traditional planetary gear speed reducers with few teeth difference or harmonic planetary gear speed reducers with few teeth difference, it has the advantages of high precision, high reduction ratio and high service life without any flexible components. [Description of the Drawings]

[0038] The following further describes the present invention with reference to the preferred embodiments of the present invention:

[0039] Figure 1 , Figure 2 Explosion and overall schematic diagram of the harmonic differential planetary gear speed reducer with few teeth difference.

[0040] Figure 3}Schematic cross-sectional view of the harmonic differential planetary gear speed reducer with few teeth difference through the axis

[0041] Figure 4}Schematic cross-sectional view of the harmonic differential planetary gear speed reducer with few teeth difference perpendicular to the axis

[0042] Explanation of the reference numerals in the figures:

[0043] 1 Ring gear A

[0044] 2 Ring gear B

[0045] 3 Planetary gear C

[0046] 4 Planetary gear D

[0047] 5 Ring gear axis

[0048] 6 Planetary axis

[0049] 7 Housing part

[0050] 8 Cam

[0051] 9 Engagement part of ring gear 1 and planetary gear 1

[0052] 10 Engagement part of ring gear 2 and planetary gear 2

[0053] 11 Low-speed shaft​​​

[0054] 12 High-speed shaft

[0055] 13 Tooth ring axis center

[0056] 14 Planet axis center [Specific implementation manner]

[0057] As Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 shown:

[0058] Figure 1 , Figure 2 are the external views and exploded views seen from two oblique directions.

[0059] The tooth ring A (1) and the tooth ring B (2) are coaxial (the same tooth ring axis center (13) and tooth ring axis (5)), and are respectively connected to the high-speed shaft (12) and the low-speed shaft (11) of the speed reducer; the planetary gear C (3) and the planetary gear D (4) are coaxial (the same planet axis center (14) and planet axis (6)), and are installed on the same rotating disk (the disk cam part of the cam (8)), and as planetary gears are respectively tangent to the tooth ring A (1) and the tooth ring B (2), see the joint part (9) of the tooth ring A and the planetary gear C and the joint part (10) of the tooth ring B and the planetary gear D; the tooth ring axis (5) is parallel to the planet axis (6) and has a spacing; the cam part of the cam (8) is a disk perpendicular to the above-mentioned axis, and the axis passes through the center of the circle. The disk restricts the free rotation of the two fixedly installed planetary gears C (3) and D (4) processed on the same axis center through bearings; after the disk cam part of the cam (8) is eccentrically (rigidly) installed on the high-speed shaft (12), rotating the high-speed shaft (12) can drive the revolution of the cam (8); making the planet axis (6) revolve parallel around the tooth ring axis (5) with an unchanged spacing; multiple housing parts (7) play a role in supporting and guiding the rotating shaft.

[0060] ​Working principle: First, the combination of the two pairs of independent planetary motions is between the ring gear A (1) and the planetary gear C (3), and between the ring gear B (2) and the planetary gear D (4); when the ring gear A (1) is constrained to be stationary, since the planetary gear C (3) is inside the ring gear, the number of teeth is less than that of the ring gear A (1); therefore, the revolution speed of the cam (8) driven by rotating the high-speed shaft (12) is greater than the rotation speed of the planetary gear C (3), manifested as: the angular displacement of the planetary gear C (3) is less than the angular displacement of the cam (8); similarly, the angular displacement of the planetary gear D (4) is also less than the angular displacement of the cam (8), that is, the angular displacement of the cam (8) is greater than the angular displacement of the planetary gear D (4); since the difference in the number of teeth between the planetary gear and the ring gear is small (the difference in the number of teeth is not large), the difference in speed is not large either. Thus, the rotational speed relationship between the high-speed shaft (12) and the low-speed shaft (11): the rotational speed ω1 between the ring gear A (1) and the planetary gear C (3) is superimposed on the rotational speed ω2 between the ring gear B (2) and the planetary gear D (4); since the directions of the two rotational speeds are opposite, the superimposed rotational speed is their difference (ω1 - ω2).

[0061] Independent adjustment parameters: The relationship between the pitch circles, the number of teeth, etc. between the ring gear A (1) and the planetary gear C (3), and between the ring gear B (2) and the planetary gear D (4), and the difference (ω1 - ω2) can be positive, negative, or even zero; this means forward transmission, reverse transmission, a larger reduction ratio, or even infinity.

Claims

1. A differential planetary reducer with few teeth difference, its structure includes: Ring gear or sun gear, cam, planetary gear; Working principle: First, the combination of two pairs of independent planetary motions exists between ring gear A and planetary gear C, and between ring gear B and planetary gear D; when ring gear A is constrained to be stationary, since planetary gear C is inside the ring gear, its number of teeth is less than that of ring gear A; thus, the revolution speed of the cam driven by rotating the high-speed shaft is greater than the rotation speed of planetary gear C, manifested as: the angular displacement of planetary gear C is less than that of the cam; similarly, the angular displacement of planetary gear D is also less than that of the cam, that is, the angular displacement of the cam is greater than that of planetary gear D; due to the small tooth difference between the planetary gear and the ring gear, the speed difference is not large either. Therefore, the rotational speed relationship between the high-speed shaft and the low-speed shaft: the rotational speed ω1 between ring gear A and planetary gear C, plus the rotational speed ω2 between ring gear B and planetary gear D; since the directions of the two rotational speeds are opposite, their superimposed rotational speed is their difference: ω1 - ω2; Independent adjustment parameters: the relationship between the pitch circles and the number of teeth between ring gear A and planetary gear C, and between ring gear B and planetary gear D, and the angular velocity difference: ω1 - ω2, which can be positive, negative, or even zero; this means forward transmission, reverse transmission, a larger reduction ratio, even infinity, and the reduction ratio is equal to ω1 / ω2; Its characteristics lie in: When using the combination of an internal ring gear and a planetary gear, ring gear A and ring gear B are coaxial and are respectively connected to the high-speed shaft and the low-speed shaft of the speed reducer; planetary gear C and planetary gear D are coaxial and are installed on the same turntable and are tangent to ring gear A and ring gear B respectively as planetary gears; the ring gear axis is parallel to the planetary axis and has a spacing; the cam part of the cam is a disc perpendicular to the above axis, and the axis passes through the center of the circle. This disc is used to constrain the free rotation of the two fixedly installed planetary gears C and D processed on the same axis through bearings; after the disc cam part of the cam is eccentrically and rigidly installed on the high-speed shaft, rotating the high-speed shaft can drive the revolution of the cam; enabling the planetary axis to revolve parallel to the ring gear axis with an unchanged spacing; When using the combination of a sun gear and a planetary gear, at this time the planetary gear is in the shape of an internal gear ring. It is still the superposition of the independent transmissions of two sets of sun gears and planetary gears; also, the two planetary gears are concentrically fixed on a turntable and then driven to revolve by a cam; also, the high-speed shaft and the low-speed shaft are respectively connected to their respective sun gears; the rotational speed relationship and characteristics are exactly the same as the above.

2. A differential type planetary reducer with few teeth difference according to claim 1, characterized in that: For the high-speed shaft and the low-speed shaft mentioned above, the high-speed shaft and the low-speed shaft can be the high-speed shaft and the low-speed shaft with the planetary gear as the output, and the ring gear or the sun gear is coaxially installed on the same turntable.

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