CN1021360C - Drive ratio-changing differential mechanism - Google Patents

Abstract

The present invention relates to a high-performance transmission ratio-changing differential mechanism composed of a driving wheel, a transmission shaft, a differential mechanism, a new half-shaft gear and a planet gear. The part number of the differential mechanism is completely identical to that of an ordinary bevel gear differential mechanism, and the structure is simpler than that of a high-friction differential mechanism. The present invention has the advantages of long service life, low cost, etc. The tyre wear rate of wheel-type engineering machinery can be greatly reduced; the present invention is particularly suitable for engineering machinery of mechanical loaders, etc., and vehicles of cross-country vehicles, dump trucks, etc., and the present invention can widely replace differential locks and the high-friction differential mechanisms.

Description

Drive ratio-changing differential mechanism

The invention belongs to mechanical manufacturing field.

Differential mechanism is a vitals in the engineering machinery such as various types of automobiles, loader, and its effect is that two driving wheels of vehicle can be rotated with friction speed, thereby vehicle can be turned.Visible Fig. 1 of differential mechanism principle commonly used, the moment of torsion that distributes on its two driving wheels are basic equating.If one of them driving wheel is trapped in when skidding in the mud, the driving wheel of opposite side does not transmit too big moment of torsion yet, and vehicle also just is difficult to deviate from automatically predicament, and this is the problem that the vehicle regular meeting of travelling on the road surface that is difficult to walk runs into.

In order to overcome this shortcoming, need take some measures, make that the torque distribution on two driving wheels might change as required.The way of using has three at present, and (1) adopts differential lock, and (2) adopt control slip differential limited, and (3) adopt the variable ratio differential mechanism.The benefit that adopts differential lock is that the locking coefficient maximum value of the ratio of fast runner transmitting torque (the slow-speed wheel with) is for infinitely great, shortcoming is that differential lock has only when vehicle sticks and could engage, use very inconveniently, and vehicle lost inertia after sticking, will extract mud ground again and be not easy.In addition, just turn, overturn accident then takes place easily if the driver has forgotten to open differential lock.Structurally also need an additional cover operation equipment in addition.

The locking coefficient of control slip differential limited also can be done greatlyyer, but their complex structure, and working life is short, neither a kind of desirable structure.

The main feature of variable ratio differential mechanism is to have adopted the differential gear profile of tooth of particular design, when trend appears skidding in a side drive wheel, it can change slightly soon than opposite side wheel, this moment, above-mentioned special tooth profile impelled the planet wheel in the differential mechanism to depart from the equilibrium position, and make the moment of torsion that is assigned on fast runner and the slow-speed wheel not wait (little on the fast runner, on the slow-speed wheel greatly) thus played the effect that prevents skidding.Because this differential mechanism only need change tooth-formation of gear and not increase other part, so simple in structure, easy to use.

But the performance of the variable ratio differential mechanism of external at present development and use is not high, locking coefficient can only reach 1.5, the differential mechanism of using on the car of the big Dodge of the U.S. for example, can not satisfy the needs of most of vehicles that on abominable road surface, travel, this in addition tooth-formation of gear processing difficulties, general factory can't make, thereby application is not extensive, can't replace differential lock or control slip differential limited.

The present invention is exactly at above-mentioned deficiency, and it is bigger to develop a kind of locking coefficient, the better variable ratio differential mechanism of performance.

Drive ratio-changing differential mechanism provided by the present invention is made up of driving, transmission shaft, differential mechanism, differential gear, planetary pinion etc., its main points be differential gear and planetary pinion pitch cone with the top flank profil for its couple gear pitch cone with the bottom flank profil by

$\frac{{\mathrm{d\; \Phi }}^{\mathrm{(1\; )}}}{{\mathrm{d\; \Phi }}^{\mathrm{(\; 2\; )}}}=\frac{Z_2}{Z_1}{\mathrm{〔\; 1-CratSin\; (\; Z}}_2\Phi {}^{\mathrm{(2)}}{\mathrm{)\; +\; C\; (1\; -\; rat)\; Sin\; (3Z}}_2\Phi {}^{\mathrm{(2)}}\mathrm{)\; 〕}$

The conjugate tooth profiles that the characteristics of motion that provides obtains, Z ₁-half shaft wheel the number of teeth, Z ₂-planet wheel the number of teeth, Φ ⁽¹⁾-half shaft wheel corner, Φ ⁽²⁾-planet wheel corner, C-velocity ratio variation coefficient, its optimum valuing range can be 0.12-0.20, the rat-partition coefficient, its optimum valuing range is 0.90-1, differential gear and planetary pinion pitch cone are respectively the part that the vertex of a cone is positioned at two tangent conical surfaces on pitch cone summit with the bottom tooth surface shape, and vertex of a cone half-angle is used Γ respectively ⁽¹⁾And Γ ⁽²⁾Represent Γ ⁽²⁾Optimum valuing range can be 30 °～60 °, Γ ⁽¹⁾Then by Γ ⁽¹⁾=tg ^-11/ (kp-ctg Γ ⁽²⁾) determine that Kp represents the induced normal curvature at pitch cone place in the formula.

$\mathrm{Kp\; =}\frac{1}{{\mathrm{Sina}}_o{\mathrm{Sin\; \theta }}_o{}^{\mathrm{(2)}}{\mathrm{Cos\; \theta }}_o{}^{\mathrm{(2)}}{\mathrm{-\; \epsilon }}_1{\mathrm{Cosa}}_o{\mathrm{Cos}}^2{\theta }_o{}^{\mathrm{(2)}}}$

${\epsilon }_1=\frac{Z^2{}_{2}C}{Z_1}\mathrm{(3\; -\; 4rat\; )}$

${\theta }_o{}^{\mathrm{(2)}}\mathrm{=\; tg}{}^{\mathrm{-1}}\frac{Z_2}{Z_1}$

α _oThe pressure angle at-pitch cone place, 20 °-27 ° of spans.

Planetary pinion in the circular thickness at pitch cone place by fp(2)=(π L _o)/(Z ₂) determine.And do not allow attenuate, L in the formula _oThe Outer cone distance of-gear pair.Differential gear in the circular thickness at pitch cone place by fp ⁽¹⁾=(3 π-2C (4rat-1))/(3Z ₁) LoCos θ _o ⁽²⁾Determine that spt-reserves circumferential sideshake in the formula.

Part number of the present invention and common bevel differential are identical, and structure is simple more than control slip differential limited, and locking coefficient can reach 2.9～3.1, and sideshake is even.It is long that the present invention has the life-span, low cost and other advantages.Also can alleviate the labor intensity of driver simultaneously and improve the passing capacity of vehicle on the road surface that is difficult to walk, improve operating efficiency, and reduce the tire wear rate of industrial wheeled equipment greatly.Gear in this differential mechanism adds and can the bilateral flank profil be shaped simultaneously man-hour on the gear generator through repacking, and manufacturing efficiency is not less than the bevel gear in the open differential.Engineering machinery such as the present invention is specially adapted to loader, bulldozer and offroad vehicle, vehicles such as dump truck, but and large size eliminate differential lock and high friction differential mechanism, make the updating and upgrading of a product.

Embodiment: the variable ratio differential mechanism that is used for 40 type rope Ma Qiao.This ransaxle can be contained on ZL40 type loader or the wheeled vibratory roller.This variable ratio differential mechanism is to convert on the bevel gear differential of former rope Ma Qiao, two changes have only been done, one is with the requirement redesign by variable ratio of the differential gear in the differential mechanism and planetary pinion, another is in order to adapt to the bigger characteristics of newly-designed differential gear thickness, the back supporting end face of differential gear on the differential casing 6 millimeters have been dug deeply, the remaining parts of differential mechanism is not all changed, and its working principle as shown in Figure 1.When redesign differential gear and planetary pinion behind multi-parameters optimization determined gear parameter as follows: the half shaft wheel number of teeth-Z ₁=12, the planet wheel number of teeth-Z ₂=7, α=24 °, velocity ratio variation coefficient-C=0.16, partition coefficient-rat=0.98, vertex of a cone half-angle-Γ ⁽²⁾=45.4 °, reference cone bus length=74.79mm.The characteristics of motion according to above-mentioned design parameter gear pair is:

(dΦ ⁽¹⁾)/(dΦ ⁽²⁾) ＝ 7/12 〔1-0.16×0.98Sin（7Φ ^（2））+0.16（1-0.98）Sin（3×7Φ ^（2））〕

The following partly flank profil of differential gear and planetary pitch cone all is a conical surface, and the following partly flank profil of pitch cone is tried to achieve according to above-mentioned characteristics of motion pointwise.The differential gear and the planetary pinion of redesign are shown in accompanying drawing 2 and accompanying drawing 3 respectively.Above-mentioned flank profil is shown in accompanying drawing 4 and accompanying drawing 5 respectively with the unfolded drawing of the intersection of differential gear and planetary pinion back cone respectively.The measured value that these two back cones launch profile of tooth is listed in table 1.H in the table ₁Represent the height of each measuring point, s to the differential gear calibration conical surface ₁On the expression gear teeth corresponding to the chordal thickness of above-mentioned each measuring height; H in the table ₂Represent the height of each measuring point, s to the planetary pinion calibration conical surface ₂On the expression planet wheel corresponding to the chordal thickness of above-mentioned each measuring height.

S in the table 1 ₁=15.227 and s ₂=16.807 represent differential gear respectively at the chordal thickness at pitch cone place and the planetary pinion chordal thickness at the pitch cone place, and they are bases:

Fp ⁽¹⁾=(3 π-2C (4rat-1))/(3Z ₁) LoCos θ ^{O (2)}-spt and fp ⁽²⁾=(π L _o)/(Z ₂)

Obtaining circular thickness and the planetary pinion of differential gear at the pitch cone place changes after adjust gained in the circular thickness at pitch cone place.

Through test, the locking coefficient of above-mentioned differential mechanism is 3.0.The vibratory roller that above-mentioned differential mechanism is housed has used in the Chengdu-Chongqing expressway road construction work and surpassed 1500 hours, and is functional.

The measured value that two back cones of table 1 launch profile of tooth

h ₁s ₁h ₂s ₂

8.762 6.903 10.968 7.006

7.213 8.718 8.896 10.444

3.981 11.800 6.922 12.232

-0.226 15.227 3.516 14.537

-4.335 18.073 -0.817 16.807

-7.342 19.860 -3.041 17.755

-9.037 20.716 -7.015 19.109

-9.370 19.710

Accompanying drawing 1 is a variable ratio differential mechanism sketch.(1) is driving wheel among the figure, and (2) are transmission shafts, and (3) are differential mechanisms, and (4) are differential gears, and (5) are planetary pinions.

Accompanying drawing 2 is differential gear schematic representation.(6) are pitch cones among the figure, and (7) pitch cone is with the top flank profil, (8) be pitch cone with the bottom flank profil, (9) are the pitch cone summits.

Accompanying drawing 3 is planetary pinion schematic representation, and (6) are pitch cones among the figure, (7) be pitch cone with the bottom flank profil, (8) be pitch cone with the bottom flank profil, (9) are the pitch cone summits.

Accompanying drawing 4 is that the back cone of differential gear launches profile of tooth, h among the figure ₁The height of the expression calibration conical surface, s ₁Correspondence and h on the expression gear teeth ₁Chordal thickness.

Accompanying drawing 5 is back cone spread profiles of tooth of row gear, h among the figure ₂The height of the expression calibration conical surface, s ₂Correspondence and h on the expression gear teeth ₂Chordal thickness.

Claims (5)

1, a kind of drive ratio-changing differential mechanism, it is made up of driving wheel (1), transmission shaft (2), differential mechanism (3), differential gear (4), planetary pinion (5), it is characterized in that differential gear and planetary pinion pitch cone (6) are that its couple gear pitch cone is pressed (d Φ with bottom flank profil (8) with top flank profil (7) ⁽¹⁾)/(d Φ ⁽²⁾)=(Z ₂)/(Z ₁) [1-Cratsin (Z ₂Φ ⁽²⁾)+C (1-rat) sin (3Z ₂Φ ⁽²⁾)] conjugate tooth profiles that the characteristics of motion that provides obtains, differential gear and planetary pinion pitch cone are respectively the part that the vertex of a cone is positioned at two tangent circular cones on pitch cone summit (9) with the bottom tooth surface shape.

2,, it is characterized in that the vertex of a cone half-angle Γ of differential gear reference cone with the bottom flank of tooth according to the described variable ratio differential mechanism of claim 1 ⁽¹⁾With the vertex of a cone half-angle Γ of planetary pinion reference cone with the bottom flank of tooth ⁽²⁾Obey Γ ⁽¹⁾=tg ^-11/ (k _p-ctgr ⁽²⁾) relation, k _pThe induced normal curvature at expression pitch cone place, Γ ⁽²⁾Optimum valuing range can be 30 °～60 °.

3, according to claim 1,2 described variable ratio differential mechanisms, it is characterized in that differential gear in the circular thickness at pitch cone place by fp ⁽¹⁾=(3 π-2c (4rat-1))/(3Z ₁) L _oCos θ _o ⁽²⁾Determine, planetary pinion in the circular thickness at pitch cone place by fp ⁽²⁾=(π L ₃)/(Z ₂) determine, and do not allow attenuate.

4,, it is characterized in that the optimum valuing range of c in the formula can be 0.12～0.20, the optimum valuing range of rat can be 0.90～1 according to claim 1,2 described variable ratio differential mechanisms.

5,, it is characterized in that the optimum valuing range of c in the formula can be 0.12～0.20, the optimum valuing range of rat can be 0.90～1 according to the described variable ratio differential mechanism of claim 3.

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