CN100353087C - Transmission device of having nutation oscillating tooth - Google Patents

Abstract

The present invention discloses a transmission device with nutation movable teeth, which comprises an input shaft and an output shaft, wherein an offset shaft section position of the input shaft is connected with a nutation disk by bearing connection; one end surface of the nutation disk facing the input shaft is engaged with a fixed disk via movable teeth of a first steel ball group, the movable teeth are distributed on circumferential direction with intervals, and the fixed disk is fixedly connected with a machine base; one end surface of the nutation disk facing the output shaft is engaged with a rotating disk via movable teeth of a second steel ball group, the movable teeth are distributed on circumferential direction with intervals, and a bearing is arranged between the rotating disk and the machine base. A rolling pair steel ball is used as an intermediate body, the nutation disk is respectively in rolling engagement with the movable teeth between the fixed disk and the planetary rotating disk on the output shaft, and the nutation disk can realize the engagement transmission of a permanent velocity ratio. The device is suitable for accurate transmission mechanisms and has the characteristics of high transmission accuracy, high transmission rigidity, high transmission efficiency, little part number, small volume, light weight, large transmission ratio, long service life, high bearing capability and no output mechanism.

Description

Nutation oscillating tooth transmission device

Technical Field

The present invention relates to a transmission, and more particularly to a planetary transmission with movable teeth meshing.

Background

In the field of machinery, a traditional transmission mode adopts gear transmission; the meshing teeth are usually in the form of fixed teeth, which must be kept free of play for meshing. Due to the existence of the gap, the requirements of high bearing capacity, high precision, high reliability, large speed ratio and small volume mechanical transmission in the prior art cannot be met. In order to eliminate the clearance and make up the defects of the conventional gear transmission, a movable meshing gear transmission mode is adopted at the present stage, and the mode can realize zero-clearance transmission. In recent years, the application of oscillating tooth transmission mainly focuses on plane and cylindrical surface oscillating tooth transmission modes.

For example, chinese patent No. CN97123214.8 discloses a cycloidal steel ball planetary reducer, which includes an eccentric shaft mounted on an input shaft and balance blocks on both sides of the eccentric shaft, a cycloidal planetary gear mounted outside the eccentric shaft, a steel ball wheel integrated with the output shaft, and external gears having short cycloidal circular tooth surfaces at both ends of the cycloidal planetary gear, and forming inner gearing transmission with an end cover and a steel ball internal gear on the steel ball wheel respectively. The cycloidal steel ball planetary reducer of the patent uses a steel ball as a transmission intermediate member, and adopts an eccentric structure and a set of equiangular speed ratio mechanism to realize transmission, and the structure is complex.

Chinese patent No. CN96241067.5 discloses a high-efficiency oscillating-tooth speed reducer, which includes an input shaft, a rocker bearing is mounted outside an eccentric circular cam fixedly connected to the input shaft, and a shock wave ring is mounted outside the rocker bearing. The outer side of the shock ring is contacted with a group of swing movable teeth. Each swing movable tooth and the movable tooth pin shaft are hinged on the movable tooth frame. The outer side of the swing movable teeth is contacted with the central wheel. During transmission, the swinging movable teeth are driven by the shock wave device to be meshed with the central wheel, and the output shaft is driven to rotate at a low speed while swinging around the movable teeth pin shaft. The patent also adopts an eccentric structure, so that an output mechanism is omitted, but the defects of the patent are that the movable teeth are in line contact in the meshing process, are in a sliding and rolling meshing state and are not suitable for precise transmission.

Chinese patent No. CN01108707.2 discloses a space cam movable tooth transmission device, which relates to a small tooth difference movable tooth planetary transmission device, and the space cam movable tooth meshing pair is composed of end teeth, a movable tooth frame, ball movable teeth, a space cam and an adjusting shim. The meshing pair is accurate space meshing, is provided with an adjusting gasket to adjust the meshing gap, and realizes precise transmission by utilizing the error homogenization of movable tooth transmission multi-tooth meshing. However, the transmission device of the patent belongs to space cylindrical surface oscillating tooth transmission, the tooth profile derivation is more complex, and only two-tooth difference planetary transmission can be realized.

In the book "planetary transmission design and calculation" published by 1997 in 12 months and edited by Hulai Lopa, pages 306-317 elaborated the principle and structure of the deflection cone-difference planetary transmission, which uses the nutation mathematical physics concept to explain the transmission mode and realizes the multi-tooth meshing transmission in the low-speed and large-torque occasions by adopting the deflection bevel gear with inner bevel gear. However, the transmission theory and the technology are relatively immature, are not widely applied and are not suitable for precise transmission.

Disclosure of Invention

The invention provides a nutation oscillating tooth transmission device aiming at the problems, and is a novel planetary transmission device. The problems of complex structure, large volume, low transmission efficiency and low bearing capacity of the similar devices are solved, and the device is suitable for precision transmission of precision servomechanisms such as robots, precision machine tools, aerospace and precision testing instruments.

In order to solve the problems, the invention constructs a nutation oscillating tooth transmission device, which comprises an input shaft 1 inserted in an end cover 2 and a base 5 and supported by a support bearing 25, and an output shaft 16 inserted in a bearing end cover 17, wherein the offset shaft section position of the input shaft 1 is connected with a nutation disc 21 through a bearing; the end face of the nutation disc 21 facing the input shaft 1 is meshed with a fixed disc 7 through spherical movable teeth of first steel ball groups 11 arranged at intervals in the circumferential direction, and the fixed disc 7 is fixedly connected to a machine base 5; the end face of the nutation disk 21 facing the output shaft 16 is meshed with a rotating disk 19 through spherical movable teeth of second steel ball groups 14 arranged at intervals in the circumferential direction, a bearing 12 is arranged between the rotating disk 19 and the machine base 5, and the rotating disk 19 is connected to the output shaft 16.

The invention further improves the nutation oscillating tooth transmission device, two end surfaces of the nutation disc 21 are provided with pre-tightening covers 8, and meshing surfaces are arranged between the pre-tightening covers 8 and the steel ball groups 11 and 14.

The invention further improves the nutation oscillating tooth transmission device, and the nutation disc 21 is connected with the pre-tightening cover 8 through a pre-tightening gasket and a pre-tightening screw 9; the section forms of the nutation disc 21, the pre-tightening cover 8 and the steel ball meshing groove are linear, single circular arc or double circular arc.

The invention further improves the nutation oscillating tooth transmission device, wherein the input shaft 1 and the offset shaft section are integrally connected, or the input shaft 1 is provided with an offset shaft section sleeve 30 through key connection.

Through the technical scheme, the nutation oscillating tooth transmission device is a novel planetary transmission device which is innovatively designed on the basis of a deflection cone difference planetary transmission speed reducer by utilizing the nutation mathematical physical concept. The steel ball of the rolling pair is used as an intermediate body, and the rolling engagement of the movable teeth between the nutation disk arranged on the input shaft and the fixed disk and between the planetary disks on the output shaft is realized to realize the engagement transmission of constant speed ratio. The device of the invention has the advantages that: compared with the planetary speed reducer with small tooth difference, the planetary speed reducer saves a set of equiangular speed ratio mechanism, also reduces the number of parts and reduces the volume of the mechanism. The position of the pre-tightening cover on the nutation disc is adjusted, so that the meshing gap can be eliminated, and the transmission device obtains high transmission precision by utilizing the error homogenization of multi-tooth meshing in movable tooth transmission; the shock wave device forms accurate space meshing transmission with the fixed disc and the rotating disc respectively in the meshing process, and the tooth profile curve is continuous, so that meshing impact caused by discontinuous tooth profile is eliminated; the number of the meshing teeth is equal to the number of all the steel balls, the bearing capacity is high, and motion and power can be transmitted. The transmission device is suitable for being applied to the transmission devices of precision servo mechanisms of robots, precision machine tools, aerospace, precision testing instruments and the like; the transmission mechanism has the characteristics of high transmission precision, high transmission rigidity, high transmission efficiency, small part number, small volume, light weight, large transmission ratio, long service life, large bearing capacity and no need of an output mechanism.

Drawings

FIG. 1 is a schematic view of a nutating oscillating tooth drive of the present invention;

FIG. 2 is a schematic view of the tooth slot configuration of the stationary plate of the nutating oscillating tooth drive of the present invention;

FIG. 3 is a schematic view of the tooth space configuration of the rotating disk of the nutating oscillating tooth drive of the present invention;

FIG. 4 is a schematic view of the spline structure rotating in the opposite direction relative to the rotating disk of FIG. 3;

FIG. 5 is a schematic representation of a tooth form derived mathematical model of the nutating oscillating tooth drive of the present invention;

FIG. 6 is a schematic cross-sectional view of a linear groove of a nutating disk and steel ball engagement pair of the nutating oscillating tooth transmission of the present invention;

FIG. 7 is a schematic cross-sectional view of a single circular groove of a nutating disk and a steel ball meshing pair of the nutating oscillating tooth transmission device of the present invention;

FIG. 8 is a schematic cross-sectional view of a double circular arc groove of a nutating disk and a steel ball meshing pair of the nutating oscillating tooth transmission device of the present invention;

FIG. 9 is a schematic view of a nutating oscillating tooth transmission input shaft with an offset shaft segment sleeve according to the present invention.

In fig. 1: 1 input shaft, 2 bearing end covers, 5 engine bases, 7 fixed disks, 8 pre-tightening covers, 9 pre-tightening cover screws, 10 pre-tightening cover gaskets, 11 first steel ball groups, 12 bearings, 13 sleeves, 14 second steel ball groups, 15 gaskets, 16 output shafts, 17 bearing end covers, 19 rotating disks, 20 rotating disk tooth grooves, 21 nutation disks, 22 fixed disk tooth grooves, 23 sleeves, 24 bearings, 25 supporting bearings and 26 sealing rings

Detailed Description

The nutation oscillating tooth transmission device structure of the invention is shown in figure 1, wherein, the nutation oscillating tooth transmission device comprises an input shaft 1 which is inserted in an end cover 2 and a machine base 5 and is supported by a support bearing 25, and an output shaft 16 which is inserted in a bearing end cover 17; the end cover 2 and the bearing end cover 17 are fixed on the base 5 through screws, a gasket 15 is arranged at the connecting part of the end cover and the base, and the connecting position of the end cover 2 and the input shaft 1 is sealed by a sealing ring 26. An offset shaft section of the input shaft 1 is connected via bearings to a nutating disk 21. The input shaft is offset from the shaft section, and can be integrally manufactured with the input shaft in order to reduce cost and ensure processing efficiency during mass production; the arrangement of the offset shaft section sleeve 30 on the input shaft can also be adopted, as shown in fig. 9, the sleeve 30 is connected with the nutating disc through a bearing, and in this way, the flexible replacement of the device can be ensured, and the service life of parts can be prolonged. In addition, the end surface of the nutation disk 21 facing the input shaft 1 is meshed with the fixed disk 7 through spherical movable teeth of the first steel ball group 11 arranged at intervals in the circumferential direction, and the fixed disk 7 is fixedly connected to the machine base 5; the end face of the nutation disc 21 facing the output shaft 16 is meshed with a rotating disc 19 through spherical movable teeth of second steel ball groups 14 arranged at intervals in the circumferential direction, a bearing 12 is arranged between the rotating disc 19 and the machine base 5, and the rotating disc 19 is connected with the output shaft 16.

The end face of the nutation disc 21 is provided with a pre-tightening cover 8 through a pre-tightening gasket 10 and a pre-tightening screw 9, and meshing surfaces are arranged between the pre-tightening cover 8 and the steel ball groups 11 and 14. As shown in fig. 6, the cross-sectional form of the nutating disc 21 and the preload cap 8 and the ball engaging groove is linear, and a single circular arc as shown in fig. 7 or a double circular arc as shown in fig. 8 may be employed.

The working principle of the nutation oscillating tooth transmission speed reducer is as follows: firstly, an input shaft, a nutation disk, a steel ball, a fixed disk, a rotating disk and a space spherical movable tooth meshing pair formed by the input shaft, the nutation disk, the steel ball, the fixed disk and the rotating disk are arranged in a main body; the steel ball of the rolling pair is used as an intermediate body, and the rolling engagement of the movable teeth between the nutation disk arranged on the input shaft and the fixed disk and between the planetary disks on the output shaft is realized to realize the engagement transmission of constant speed ratio. The steel ball of the rolling pair is an intermediate body, and the meshing state of the steel ball can be adjusted by adjusting the pre-tightening cover on the nutation disc, so that the backlash-free meshing in the transmission process is realized. The space spherical surface movable tooth meshing pair comprises a fixed disc tooth profile which is a space curved surface formed by the steel ball which generates deflection motion along the spherical surface. The transmission ratio of the speed reducer is determined by an included angle alpha between the axis of the nutating disc and the axis of the input shaft and an included angle beta between the spherical center of the steel ball loaded on the nutating disc and the axis of the nutating disc. The performance of the speed reducing device is comprehensively considered, and the value range of the alpha angle is optimally 8-20 degrees. Different transmission ratios can be obtained by varying the angle; of course, according to the principle of nutation motion, the size of an included angle beta between the center of a steel ball pre-tightened on the nutation disc through the pre-tightening cover and the axis of the nutation disc is changed, and different transmission ratios can also be obtained; the tooth profile of the rotating disc is a space curved surface formed by the steel ball which generates deflection motion along the spherical surface and generates relative motion with the rotating disc. The input shaft and the nutation disk form a shock wave device with space spherical oscillating tooth transmission, and the difference between the wave number generated by the tooth profile of the fixed disk and the wave number generated by the tooth profile of the rotating disk by the shock wave device is 1, namely, the planetary transmission with tooth difference is generated.

A mathematical model is derived by establishing the tooth form of the nutating oscillating tooth drive of the present invention as shown in fig. 5; the tooth profile structures of the fixed disc and the rotating disc can be solved. In the prior art, the transformation matrix rotating around the coordinate axes is as follows:

$E^{\mathrm{k\θ}}=\left[\begin{array}{ccc}\cos \mathrm{\θ}& -\sin \mathrm{\θ}& 0\\ \sin \mathrm{\θ}& \cos \mathrm{\θ}& 0\\ 0& 0& 1\end{array}\right]$ $E^{\mathrm{j\θ}}=\left[\begin{array}{ccc}\cos \mathrm{\θ}& 0& \sin \mathrm{\θ}\\ 0& 1& 0\\ -\sin \mathrm{\θ}& 0& \cos \mathrm{\θ}\end{array}\right]$ $E^{\mathrm{i\θ}}=\left[\begin{array}{ccc}1& 0& 0\\ 0& \cos \mathrm{\θ}& -\sin \mathrm{\θ}\\ 0& \sin \mathrm{\θ}& \cos \mathrm{\θ}\end{array}\right]$

wherein E^kθ、E^jθ、E^iθIs a transformation matrix rotated by theta angle around the k, j and i axes in the figure

Deriving the following formula according to the transformation matrix of the spatial mechanism rotating around the coordinate axis:

is provided with

For fixing the spherical center of the steel ball on the side of the plateA position vector of

As shown in figure 4 of the drawings,

r₀from the center of the steel ball to the origin O of the coordinate system in the space sphere₀The radius value of (d);

beta is the included angle between the connecting line of the ball centers of the steel balls at the diagonal of the half section of the nutating disc and the axis of the nutating disc,

beta is as shown in FIG. 1, is taken ${\mathrm{\β}}_1={\mathrm{\β}}_2=\frac{\mathrm{\π}}{2}-\mathrm{\β}$

E^ω(2mπ/Zb1)Transformation matrix of revolution about an arbitrary axis omega, m being (0, … …, Z)_b1-1)，

Z_b1The number of the steel balls in the first steel ball group

E^j(α+β1)Transformation matrix rotating around arbitrary axis j, angle of rotation (alpha + beta)₁)

E^ω*Conversion matrix of nutating disc rotating * degrees around omega axis

E^kθTransformation matrix for nutating disc rotating by theta angle around k axis

Wherein * is the angle the nutating disc rotates, * is-theta, theta is the angle of the input shaft

Z_b1＝Z_b2(when designing)

When the input shaft is rotated by an angle theta,

the position of the vector

Then: r₀＝(r₀，0，0)^T

$P_0=E^{w(2\mathrm{m\π}/z_{b1})}{E}^{j(\mathrm{\α}+{\mathrm{\β}}_1)}{R}_0$

P₁＝E^w*E^kθP₀ *＝-θ

Wherein,

${(\mathrm{\λ},\mathrm{\μ},v)}^T={(\cos \mathrm{\θ}\sin \mathrm{\α},\sin \mathrm{\θ}\sin \mathrm{\α},\cos \mathrm{\α})}^T$

in the same way, set

Is the position vector of the center of the second steel ball group

Z_b2Number of steel balls of second steel ball group

When the input shaft is rotated through an angle theta,

the position of the vector

Is the position vector of the output shaft when rotating through an angle gamma relative to the input shaft

Then

$Q_0=E^{w(2\mathrm{n\π}/Z_{b2})}{E}^{j(\mathrm{\α}+{\mathrm{\β}}_2)}{R}_0$ Q₁＝E^-wθE^kθQ₀

R₁＝E^-kγQ₁ $\mathrm{\γ}=\±\frac{1}{I_n}\mathrm{\θ}$ I_n＝Z_b1-1＝Z_b2-1

Note: if the input shaft rotates by an angle theta, the output shaft relatively rotates

Transmission ratio $i=\frac{\mathrm{\θ}}{\±\frac{1}{I_n}\mathrm{\θ}}=\±I_n,$ I.e. I_nIs a transmission ratio value

Therefore, according to the above mathematical model, a specific γ is input₀After the parameters of alpha, beta and the like, the central position of the steel ball on the side opposite to the fixed plate can be obtained

When rotated by an angle theta

Vector quantity; can also obtain the rotation of the output shaft $\mathrm{\γ}=\±\frac{1}{I_n}\mathrm{\θ}$ Position vector at angle. Therefore, theoretical tooth profile curves of the fixed disc tooth grooves and the rotating disc tooth grooves can be established according to the mathematical model. In numerical control machiningIn the above-described model, the coordinate values of the spatial rectangular coordinate system X, Y, Z are obtained, and then the tooth profile is machined.

Fig. 2 and 3 are tooth profile graphs of a nutating oscillating tooth transmission of the invention at a transmission ratio of 18, and fig. 2 is a tooth profile curve shape structure of a fixed-disk tooth slot 22; FIG. 3 is a tooth profile curve shape configuration of the rotary disk spline 20; FIG. 4 is a graph showing a spline structure rotated in the reverse direction with respect to the rotary disk of FIG. 3.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.

Claims (5)

1. A nutation oscillating tooth transmission device comprises an input shaft (1) inserted in an end cover (2) and a machine base (5) and supported by a support bearing (25), and an output shaft (16) inserted in a bearing end cover (17), and is characterized in that the offset shaft section of the input shaft (1) is connected with a nutation disc (21) through a bearing; the end face, facing the input shaft (1), of the nutation disc (21) is meshed with a fixed disc (7) through first steel ball groups (11) arranged at intervals in the circumferential direction through spherical movable teeth, and the fixed disc (7) is fixedly connected to a machine base (5); the end face, facing the output shaft (16), of the nutation disc (21) is meshed with a rotating disc (19) through second steel ball groups (14) in the circumferential direction through spherical movable teeth arranged at intervals, a bearing (12) is arranged between the rotating disc (19) and the machine base (5), and the rotating disc (19) is connected to the output shaft (16);

two end faces of the nutation disc (21) are provided with pre-tightening covers (8), and meshing surfaces are arranged between the pre-tightening covers (8) and the steel ball groups (11, 14).

2. A nutating oscillating tooth drive according to claim 1, characterized in that the connection between the nutating disk (21) and the preload cap (8) is realized by means of a preload washer and a preload screw (9).

3. A nutating oscillating tooth transmission according to claim 1 or 2, characterized in that the cross-sectional form of the nutating disc (21) and of the preload cap (8) and of the ball-engaging grooves is rectilinear or single or double circular.

4. A nutating oscillating tooth transmission according to claim 1 or 2, characterized in that the input shaft (1) is integrally connected with the offset shaft section.

5. A nutating oscillating tooth transmission according to claim 1 or 2, characterized in that the input shaft (1) is provided with an offset shaft segment sleeve (30) by means of a keyed connection.

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