CN100385146C - Link lever-gear little gear difference planetary driving mechanism - Google Patents

Abstract

The present invention relates to a connecting rod-gear low-tooth-difference planetary transmission mechanism. Input power is transmitted to an inner gear engaged with the outer gear through the outer gear fixed on the middle part of the connecting rod of a four-rod mechanism; the outer gear does translational motion in the inner gear for driving the inner gear to do fixing shaft rotation for outputting torque. The connecting rod-gear low-tooth-difference planetary transmission mechanism of the present invention has the advantages of above 90 percent of transmission efficiency, larger load bearing capacity, large transmission ratio, small volume, light weight, still equilibrium and dynamic balance realization in the transmission process, convenient maintenance, lower price and wide adaptability. The present invention can be widely used for the fields of various engineering of spaceflight, biomedical engineering, minute mechanical systems, etc.

Description

Connecting rod-gear little gear difference planetary driving mechanism

Technical field

The invention belongs to connecting rod-gear little gear difference planetary driving mechanism field.

Background technique

Gear transmission be most important in the mechanical transmission, also be most widely used a kind of mechanical transmission pattern.The quality of gear and gearing directly affects quality, life-span and the performance of engineering goods.Gear transmission can realize the multiple space kinds of drive such as transmission between parallel axes, concurrent aces and the alternating axis.Gear technique indicates the level of mechanical engineering technology to a certain extent, is acknowledged as industry and industrialized symbol.

The planetary pinion transmission is compared with common fixed axis gear transmission, because effectively utilized the alignment of power dividing and input, output and rationally adopted interior engagement, have that quality is little, volume is little, velocity ratio is big, bearing capacity is big and stable drive and transmission efficiency advantages of higher, be widely used.But its complex structure is made difficulty, the cost height, and be subjected to that structural limitations can only be used for, little load transmission.

Planetary drive with small teeth difference is a kind of of planetary pinion transmission, is representing a developing direction of planetary pinion transmission.External gear teeth was counted the Modified Gear Transmission of difference interior engagement seldom in planetary drive with small teeth difference was meant, its transmission type is a lot, pressed planetary gear and distinguished, the few tooth difference transmission of cycloid is arranged, involute less tooth difference transmission, the few tooth difference transmission of circular arc, mobile tooth and small tooth difference transmission and few tooth difference transmission five classes of awl tooth.It is tooth curve that the German at first proposes with the epicycloid, and one of them gear adopts the cycloid planetary drive with small teeth difference principle of pinwheel, and in the later stage thirties 20th century in Japanese development and production.China drops into industrialized production the sixties in 20th century from the cycloidal planetary gear speed reducer that begins one's study in 1958, has now formed series, is widely used in all kinds of machinery.The part of cycloidal-pin wheel planetary drive with small teeth difference mainly adopts Bearing Steel and forms through grinding, is multiple tooth engagement during transmission, thereby has the bearing capacity height, and running is steady, efficient height, characteristics such as life-span length.But its requirement on machining accuracy height, complex structure, corresponding manufacture cost is also high.

The principle of the few tooth difference transmission of the principle of involute less tooth difference transmission and cycloidal-pin wheel is basic identical, and its difference is: the tooth curve of the former interior external gear adopts involute, and the latter's is epicycloid.1949, The former Russian scholar SkvolZova solved the geometry computational problem that realizes a tooth difference transmission theoretically.1956, the famous mechanical scholar Zhu Jing sample professor of China proposed the transmission principle and the design method of " double-crank input type few tooth difference transmission mechanism ", had instructed the research and extension of the few tooth difference transmission of China to use.The characteristics of involute less tooth difference transmission are that the gear teeth are simple in structure, just can process with common involute gear cutter and gear machine, do not need special tool and special device, also can adopt the soft flank of tooth, avoid complicated heat treatment and fine-processing technique, manufacture cost is lower.But its transmission efficiency is not as the few tooth difference transmission height of cycloidal-pin wheel.

It is the new type speed reducer of principle with the planetary drive with small teeth difference that the later stage seventies 20th century has occurred a kind of, and promptly three-ring speed reducer is characterized in that velocity ratio is big, and bearing capacity is big, the transmission efficiency height, and compact structure, volume is little, light weight.But further dwindling physical dimension has any problem with the shunting input power.

Summary of the invention

The technical problem to be solved in the present invention provides that a kind of bearing capacity and transmission efficiency height, balance are good, compact structure, volume are little, make simple connecting rod-gear little gear difference planetary driving mechanism.

The present invention solves the problems of the technologies described above with following technological scheme: the external gear by being fixed on fourbar linkage connecting rod middle part, will import transmission of power to the internal gear of its engagement, external gear is done translation in internal gear inside, drives the internal gear output torque that rotates in fixed axis.

Connecting rod-gear little gear difference planetary driving mechanism of the present invention, transmission efficiency is up to more than 90%, bearing capacity and velocity ratio are big, compact structure, small and light, and transmission process can reach the static balancing and the dynamic balancing of system, easy to maintenance, price is not high, wide adaptability, can be widely used in various engineerings, for example field such as space flight and biomedical engineering, milli machine system.

Description of drawings

Fig. 1 is the transmission principle figure of connecting rod-gear little gear difference planetary driving mechanism of the present invention.

Fig. 2 is a structural representation of using a kind of speed reducer of principle of the invention design.

Embodiment

As shown in Figure 1, external gear 4 is fixedly mounted on the connecting rod 2 of the fourbar linkage ABCD that is made up of crank 1 and 3, connecting rod 2, its center of circle O ₁Be positioned at the mid point of connecting rod 2; With the internal gear 5 of external gear engagement, its center of circle O ₂Be positioned at the gyration center A of crank 1 and 3, the mid point of D line, the centre distance O of external gear 4 and internal gear 5 ₁O ₂Length equal the length L of crank.When motor drives crank 1,3 or one of them crank up, be fixed on external gear 4 on the connecting rod BC and do each locus of point with connecting rod and be round translation, this moment the external gear center O ₁Track be with O ₂For the center of circle, with L is the circle of radius.Because the gear teeth of external gear 4 and the gear teeth of internal gear 5 are meshed, external gear 4 drives internal gear 5 around dead axle line O ₂Rotate, and the torque that deceleration increases behind the square is exported by output shaft.

Fig. 2 is a kind of speed reducer structural representation that utilizes principle design shown in Figure 1. Crank 6 and 11 is an input shaft, two driver plates 10,12 of transmitting movement and power that is the connecting rod in the quadratic crank mechanism, external gear 8 is fixed on the driver plate 10, and external gear 13 is fixed on the driver plate 12, two external gears mesh with internal gear 9 and 14 respectively, and axle 7 is the torque output shaft; The instantaneous mesh phase difference of balance plate 15 and two driver plates 10,12 is 180 degree angles, and its quality is equal to the summation of two driver plates; Owing in speed reducer, be provided with balance plate, guaranteed the static balancing and the dynamic balancing of transmission, also overcome the problem of eccentric dead point and vibration simultaneously.

The computational process of the velocity ratio of connecting rod-gear little gear difference planetary driving mechanism of the present invention, meshing parameter, efficiency analysis is as follows:

1. velocity ratio í:

In Fig. 1, the AB=CD among the parallelogram lindage ABCD, BC=AD.Motion is by crank AB or crank CD input.External gear 4 and connecting rod 2 are rigidly connected.If the number of teeth of external gear is Z ₄, Pitch radius is r ₄, the center is O ₁The number of teeth of internal gear 5 is Z ₅, Pitch radius is r ₅, the center is O ₂The P point is the instantaneous working pitch point of external gear in the Gear Planet Transmission.

AB＝DC＝r ₅-r ₄＝O ₁O ₂＝a；

${\mathrm{<figure-callout\; id="4"\; label="r"\; filenames="C20051001914800091.png"\; state="\{\{state\}\}">r</figure-callout>}}_4=\frac{1}{2}\mathrm{<figure-callout\; id="4"\; label="m\; Z"\; filenames="C20051001914800091.png"\; state="\{\{state\}\}">m</figure-callout>}{Z}_{}{}_4,{\mathrm{<figure-callout\; id="5"\; label="r"\; filenames="C20051001914800091.png"\; state="\{\{state\}\}">r</figure-callout>}}_5=\frac{1}{2}\mathrm{<figure-callout\; id="5"\; label="m\; Z"\; filenames="C20051001914800091.png"\; state="\{\{state\}\}">m</figure-callout>}{Z}_{}{}_5,O_1{\mathrm{<figure-callout\; id="2"\; label="O"\; filenames="C20051001914800091.png"\; state="\{\{state\}\}">O</figure-callout>}}_2=r_5-{\mathrm{<figure-callout\; id="4"\; label="r"\; filenames="C20051001914800091.png"\; state="\{\{state\}\}">r</figure-callout>}}_4=\frac{1}{2}m(Z_5-Z_4).$

If the rotational angular velocity of crank AB is ω, V _B=V _C=a ω.Because connecting rod BC and external gear are rigidly connected, do translation, the each point linear velocity on this member is all identical.So speed V of inside and outside point of mesh P _P=V _B, promptly

$V_P=\mathrm{a\&omega;}=\frac{1}{2}m(Z_5-Z_4)\mathrm{\&omega;}---\left(1\right)$

If the angular velocity of internal gear (that is angular velocity of output shaft) is ω ', then

${\mathrm{\&omega;}}^{\&prime;}=\frac{V_{\mathrm{<figure-callout\; id="5"\; label="P\; r"\; filenames="C20051001914800091.png"\; state="\{\{state\}\}">P</figure-callout>}}}{r_{}}=\frac{(Z_5-Z_4)}{Z_5}\mathrm{\&omega;}---\left(2\right)$

So,

$i=\frac{\mathrm{\&omega;}}{{\mathrm{\&omega;}}^{\&prime;}}=\frac{Z_5}{Z_5-{\mathrm{<figure-callout\; id="4"\; label="Z"\; filenames="C20051001914800091.png"\; state="\{\{state\}\}">Z</figure-callout>}}_4}=\frac{Z_5}{Z_P}---\left(3\right)$

In the formula, Z _P=Z ₅-Z ₄For the number of teeth of inside and outside gear poor.Know that by formula (3) input shaft of this transmission is identical with the sense of rotation of output shaft, and the size of velocity ratio í is subjected to the number of teeth and the number of teeth difference Z thereof of inside and outside gear _PDirectly influence is as difference Z _P=1 o'clock velocity ratio í equals the tooth number Z of internal gear ₅And has maximum value.

Increase internal gear number of teeth Z ₅And minimizing number of teeth difference Z _PCan increase velocity ratio.But the increase of the number of teeth can make the size of transmission increase, and reduces number of teeth difference Z _PThe diameter that makes outer gear planetary wheel and internal gear is differed very little, collide so the tooth top of meshing zone will occur, or the flank interference phenomenon, transmission can't be worked.For fear of this interference phenomenon, the main way that adopts short tooth and angle correcting in planetary drive with small teeth difference.

2, meshing parameter

The gear engagement parameter of Gear Planet Transmission and engagement physical dimension must be calculated with modification coefficient.Therefore, when the transmission of tooth difference internal-gearing planet gear is lacked in design, determine that its displacement system is very important.

The design of engagement Gear Planet Transmission is subjected to the restriction of many restrictive conditions in few tooth difference, gets final product but need only satisfy two major limitation conditions in actual use:

During (1) by meshed center distance a ' assembling, guarantee that gear transmission does not produce profile overlap interference, should satisfy overlapping interference coefficient

Gs＞Gs′(4)

(2) obtain enough contact ratios for guaranteeing, should make gear-driven contact ratio

ε _a＞ε _a′(5)

In the formula, Gs ' and ε _a' be respectively the profile overlap interference coefficient and the contact ratio of interior engagement Gear Planet Transmission of few tooth difference of designing requirement.

The profile overlap interference coefficient is

Gs＝Z ₄(δ ₄+invα _a4)+(Z ₅-Z ₄)invα′-Z ₅(δ ₅+invα _a5)(6)

The formula of contact ratio is

${\mathrm{\&epsiv;}}_a=\frac{1}{2\mathrm{\&pi;}}[Z_4({\tan \mathrm{\&alpha;}}_{a4}-\tan {\mathrm{\&alpha;}}^{\&prime;})-Z_5(\tan {\mathrm{\&alpha;}}_{a5}-\tan {\mathrm{\&alpha;}}^{\&prime;})]---\left(7\right)$

Generally speaking, ε _aShould be greater than 1.

Now get Gs ' and ε _a' be respectively Gs and ε _aDesired value, then can be write as

Gs＝Gs′(8)

ε _a＝ε _a′(9)

So, obtain set of equation

$\left\{\begin{array}{c}\mathrm{Gs}={\mathrm{Gs}}^{\&prime;}\\ {\mathrm{\&epsiv;}}_a={{\mathrm{\&epsiv;}}_a}^{\&prime;}\end{array}\right.---\left(10\right)$

Modification coefficient x ₄, x ₅Be taken as inependent mode,, find the solution this set of equation and just can obtain modification coefficient x meshingangle ' get and make intermediate variable ₄And x ₅Numerical value.Adopt the numerical solution method in the Practical Calculation, carry out iteration, in iterative computation, select for use powerful mathematical software MATHCAD to calculate with Newton method.

When require to determine Gs '=0.05, ε according to reality _a'=1.05, the parameter of input inside engaged gear transmission: Z ₄=42, Z ₅=44, m=3.5, h ^* _a=0.8, α=20 °, initial value x ⁽⁰⁾ ₄=1.0, α '=35 ° can obtain following result of calculation through the 4th iterative computation:

x ₄＝1.433mm，x ₅＝1.722mm，α′＝38.197°，ε _a＝1.05，Gs＝0.05。

3. efficiency analysis

The merit that mechanical efficiency η reflection driving force is done is utilized degree in machinery, it is expressed as the ratio of output work and input work.Definition according to mechanical efficiency η:

$\mathrm{\&eta;}=\frac{W_r}{W_d}=\frac{W_d-W_f}{W_d}=1-\frac{W_f}{W_d}---\left(11\right)$

In the formula, W _rBe output work, W _dBe input work, W _fBe the loss merit.

Efficient is an important performance indexes of Gear Planet Transmission, and can the height of efficient determine this kind transmission be applied.The mechanical efficiency of Gear Planet Transmission mainly is made up of four parts:

η＝η _e?η _b?η _w?η _M (12)

In the formula, η _eMeshing efficiency for Gear Planet Transmission; η _bEfficient for bearing; η _wEfficient for output mechanism; η _MEfficient for churning loss.

The planetary drive with small teeth difference of this paper research does not have output mechanism, and its transmission efficiency can draw with reference to formula (12):

η＝η _e?η _b?η _M (13)

3.1 the meshing efficiency of Gear Planet Transmission

Calculation Method mainly contains meshing power method, power deflection method and graphical solution, and more general with the application of meshing power method.Obtain by the meshing power method

${\mathrm{\&eta;}}_e=1+\frac{{\mathrm{\&eta;}}^H}{\frac{Z_4}{Z_5-Z_4}(1-{\mathrm{\&eta;}}^H)}---\left(14\right)$

In the formula, η ^HMeshing efficiency for transformation mechanism.For the few tooth difference internal gear transmission of dead axle, because of α '＞α _A1, node P is at line of contact B ₁B ₂Outward, so the efficiency calculation formula of transformation mechanism is as follows:

${\mathrm{\&eta;}}^e=1-\mathrm{\&pi;}*\mathrm{fg}(\frac{1}{Z_4}-\frac{1}{Z_5})[\frac{{\mathrm{<figure-callout\; id="4"\; label="Z"\; filenames="C20051001914800091.png"\; state="\{\{state\}\}">Z</figure-callout>}}_4}{2\mathrm{\&pi;}}(\tan {\mathrm{\&alpha;}}^{\&prime;}-\tan \mathrm{\&alpha;}{a}_4)+\frac{{\mathrm{<figure-callout\; id="5"\; label="Z"\; filenames="C20051001914800091.png"\; state="\{\{state\}\}">Z</figure-callout>}}_5}{2\mathrm{\&pi;}}(\tan {\mathrm{\&alpha;}}^{\&prime;}-\tan \mathrm{\&alpha;}{a}_5)]---\left(15\right)$

In the formula, f _gBe the friction factor of the flank of tooth in the engagement process, generally get f _g=0.06～0.10.

Every numerical value substitution formula (14), can obtain the meshing efficiency η of the planetary drive with small teeth difference of this paper research _e=0.968.

3.2 the efficient of bearing

The efficient of rotary arm bearing is calculated as follows:

${\mathrm{\&eta;}}_b=1-\frac{T_B}{T_H}(1+\frac{Z_5-Z_4}{Z_4})---\left(16\right)$

In the formula, T _BBe friction torque, T _HBe the pivoted arm torque.

Summary can be similar to when calculating and get η _b=0.98～0.995, η is got in the transmission of this paper research _b=0.99.

3.3 the efficient of churning loss

The efficient of churning loss is calculated as follows:

${\mathrm{\&eta;}}_M=1-\frac{0.0136V^{H}b\sqrt{E^{*}\frac{{20}^{*}}{Z_{\mathrm{\&epsiv;}}}}}{P}---\left(17\right)$

In the formula, the power of P for transmitting, KW; V ^HBe peripheral velocity, m/s; B is for immersing the width of the gear in the oil, mm; E ° is oil viscosity under the operating temperature, the condition degree; Z _εThe number of teeth for the engaging tooth wheel set.

Related parameter substitution formula (17) will be arranged, calculate η _M=0.95.

In sum, the total efficiency of the novel planetary drive with small teeth difference of this paper is

η＝η _e?η _b?η _M＝0.968×0.99×0.95＝91.04％

Claims (1)

1. connecting rod one gear little gear difference planetary driving mechanism, it is characterized in that structure is: two cranks (6,11) of parallelogram lindage are power input shaft, two driver plates (10,12) of transmitting movement and power are connecting rod, and two pairs of crank throws on described two cranks (6,11) same phase connect with corresponding described two driver plates (10,12) respectively; Two external gears (8,13) are separately fixed on described two driver plates (10,12), and mesh with two internal gears (9,14) respectively; Torque output shaft (7) is that the circle center line connecting with described two internal gears (9,14) is the axle of axis; Balance plate (15) is 180 degree angles with the instantaneous mesh phase difference of described two driver plates (10,12), and its quality is equal to the summation of described two driver plates (10,12).

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