# Automatic limited slip differential of planetary gear train

## A technology of limited slip differential and planetary gear train, applied in differential transmission, transmission, belt/chain/gear, etc. question

Active Publication Date: 2022-04-08

HUBEI UNIV OF AUTOMOTIVE TECH

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## AI-Extracted Technical Summary

### Problems solved by technology

[0003] Although the self-locking differentials that have appeared so far have good automatic anti-skid ability, whether it is mechanical or electronic differential anti-skid technology, they generally adopt a high friction torque control method, which has a frictional heating effect and torque control force. Limited, for all-terrain work, poor adaptability to all-we...

## Abstract

The invention provides a planetary gear train automatic limited slip differential which is composed of a main differential, a planetary gear train differential controller, a left driving half shaft, a right driving half shaft and a clutch, and the planetary gear train differential controller is composed of a first planetary gear train differential controller unit and a second planetary gear train differential controller unit. The first planetary gear train differential controller unit is composed of a first planetary gear train and a first overrun clutch connected with the first planetary gear train, the second planetary gear train differential controller unit is composed of a second planetary gear train and a second overrun clutch connected with the second planetary gear train, and the planetary gear train differential controller automatically limits the maximum rotating speed difference of left and right wheels. By means of the structure, a vehicle can run on a smooth road surface without slip loss, power of an engine can still be automatically transmitted to wheels with adhesive force on muddy and icy and snowy road surfaces and even under the condition that the vehicle idles on one side and has no adhesive force, slipping of the wheels is prevented, and normal running and passing of the vehicle are guaranteed.

Application Domain

Differential gearingsControl devices

Technology Topic

Limited-slip differentialControl theory +2

## Image

## Examples

- Experimental program(1)

### Example Embodiment

[0051] The embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0052] combine Figure 1-Figure 37 shown, where, Figure 4 to Figure 10 It is a reference drawing of the entity model of the main components involved in the present invention. An automatic limited-slip differential for a planetary gear train of the present invention consists of a main differential 1, a differential controller 2 of the planetary gear train, a left drive half shaft 3, The right drive half shaft 4 and the clutch 5 are composed of five parts, which are suitable for all wheeled vehicles of various sizes equipped with differentials;

[0053] The main differential 1 has the same principle as the symmetrical bevel gear differential in the prior art, but differs in structure. Shaft 1-2, planetary gear 1-3, left side gear 1-4, right side gear 1-5 and other parts. The differential housing 1-1 and the pin shaft 1-2 are connected together by bolts, the planetary gear 1-3 is installed on the pin shaft 1-2, the planetary gear 1-3 is connected with the left side gear 1-4 and the right half shaft The shaft gears 1-5 are symmetrical and constantly meshed. The left side gears 1-4 and the right side gears 1-5 are provided with internal splines in the inner holes, which are respectively connected with the external splines of the left driving half shaft 3 and the right driving half shaft 4. connected;

[0054] The planetary gear train differential controller 2 is arranged on the right side of the main differential and on the right drive half shaft. They are composed of two planetary gear train differential control units, which are defined as the first planetary gear train differential controller. unit, the second planetary gear train differential controller unit; the first planetary gear train differential controller unit is composed of the first planetary gear train and the first overrunning clutch connected with it, the second planetary gear train differential controller The unit consists of a second planetary gear train and a second overrunning clutch connected to it;

[0055] The first planetary gear train includes a first carrier 2-1, a first large sun gear 2-2, a first planetary gear 2-3, a first small sun gear 2-4, a first planet carrier 2-5, a second planetary gear The gear train includes a second support 2-13, a second large sun gear 2-9, a second planetary gear 2-10, a second small sun gear 2-11, and a second planet carrier 2-12;

[0056] The first bracket 2-1 and the main differential housing 1-1 are connected together by bolts, the first large sun gear 2-2 is fixed on the first bracket 2-1 by bolts, and the first small sun gear 2- 4 Fixed on the axle housing by bolts 2-7; the first planetary carrier 2-5 and the second planetary carrier 2-12 are connected as a whole by the spline hollow shaft 2-6, and the second planetary carrier 2-12 and the first overrun The outer rings of clutches 2-14 are connected together by bolts, and the speed is n min; The inner ring of the first overrunning clutch 2-14 and the left clutch 5-1 are connected together by splines, and the right clutch 5-2 and the right drive half shaft 4 are connected together by splines. When the clutch 5 is in the connected state, The rotational speed of the inner ring of the first overrunning clutch 2-14 and the rotational speed of the right drive axle shaft 4 and the wheels are all n 2 , at this time, when the speed n of the inner ring of the first overrunning clutch 2-14 2 Greater than the speed n of the outer ring min , the first overrunning clutch 2-14 is in an overrunning state and does not affect each other; and when the speed n of the inner ring of an overrunning clutch is 2 Less than or equal to the speed n of the outer ring min When the first overrunning clutch 2-14 is in a fit state, the inner and outer rings of the first overrunning clutch rotate together, and the rotational speed is n min , thus reaching the limit speed n 2 cannot be lower than the speed n min purpose; the second small sun gear 2-11 is fixed on the axle housing through bolts 2-8, the second large sun gear 2-9 is connected with the second bracket 2-13 through bolts, and the second bracket 2-13 It is connected with the outer ring of the second overrunning clutch 2-15 through bolts, and the speed is n max , the inner ring of the second overrunning clutch 2-15 and the left clutch 5-1 are connected together by splines, and the right clutch 5-2 and the right drive half shaft 4 are connected together by splines. When the clutch is in the connected state, the first 2. The rotational speed of the inner ring of the overrunning clutch 2-15 and the rotational speed of the right drive axle shaft 4 and the wheels are n 2 , at this time, when the speed n of the inner ring of the second overrunning clutch 2-15 2 less than the speed n of the outer ring max , the second clutch 2-15 is in an overrunning state and does not affect each other; and when the speed n of the inner ring of the second overrunning clutch 2-15 2 Greater than or equal to the speed n of the outer ring max When the second overrunning clutch is in a fit state, the inner and outer rings of the second overrunning clutch rotate together, and the rotational speed is n max , thus reaching the limit speed n 2 cannot be greater than the speed n max the goal of.

[0057] In the present invention, the rotational speed of the left and right wheels is controlled by two planetary gear train differential controller units, and the speed is limited to the allowable differential speed range n of the design. min -n max In between, so as to achieve the purpose of automatic limited slip.

[0058] In the present invention, when the rotational speed of the outer ring of the first overrunning clutch 2-14 is smaller than the rotational speed of the inner ring, it is in an overrunning state, otherwise, it is in a fit state; when the rotational speed of the outer ring of the second overrunning clutch 2-15 is greater than the rotational speed of the inner ring, In a state of transcendence, conversely, in a state of fit.

[0059] The input end 5-1 of the clutch 5 and the output end 5-2 of the clutch according to the present invention are connected together by a tooth claw. The inner side of the output end 5-2 of the clutch is provided with a spline, which is slidably sleeved on the right half drive on the axis. When reversing, turn the fork ring to make the output end 5-2 of the clutch slide along the right half drive shaft 4, and the claw connecting the input end 5-1 of the clutch and the output end 5-2 of the clutch are separated, so that the first overrun The clutch 2-14 and the second overrunning clutch 2-15 are disengaged from the right axle shaft to realize the normal reverse running of the vehicle.

[0060] In the present invention, Figure 11-Figure 37 It is a schematic structural diagram (two-dimensional line drawing) of the main components involved in the present invention to further express the present invention intuitively.

[0061] The working principle of the present invention is described below.

[0062] The working principle of a planetary gear train automatic limited-slip differential of the present invention is as follows: figure 2 As shown, the working principle of the main differential 1 in the present invention is the same as that of the conventional differential. The power of the engine is input to the main differential through the gearbox, and the power of the main differential is divided into two paths. The power is distributed to the left and right axle shafts to drive the vehicle to drive normally; the other way is input to the differential control unit of the planetary gear train through the differential case. Under normal differential conditions, this part of the idling does not consume power, and only when the wheels slip The controller only plays the role of controlling the speed when it exceeds the normal differential range.

[0063] Combine below figure 2 , image 3 The detailed description of its working principle is as follows:

[0064] The main differential speed satisfies the formula: n 1 +n 2 =2n 0

[0065] The relationship between the speed ratio of the differential control unit of the first planetary gear train is as follows:

[0066] Assume

[0067] Because gear 3 is fixed on the axle housing, and gear 5 is connected to the differential carrier, so n 3 =0, n 5 =n 0 , then there are:

[0068]

[0069] The relationship between the speed ratio of the second planetary gear system differential device control unit is as follows:

[0070] Assume

[0071] Because the planetary carriers of the two differential controller planetary gear trains are fixedly connected together, the rotational speed is the same, the gear 8 is fixed on the axle housing, n 8 =0, then there are:

[0072]

[0073] Let n 1 , n 2 At the minimum turning radius, relative to n 0 The maximum limit differential ratio is k, then:

[0074] n min =n H =(1-k)·n 0 , this speed is consistent with the speed of the outer ring of the first overrunning clutch;

[0075] n max =n 6 =(1+k)·n 0 , this speed is consistent with the speed of the outer ring of the second overrunning clutch;

[0076] β=2α; or

[0077]When the vehicle is at the minimum turning radius, the left and right differential speed is the largest. min =0.7n 0 , n max =1.3n 0.

[0078] When the car is driving in a straight line, n 1 =n 2 =n 0 , n H =0.7n 0 , n 6 =1.3n 0 , because the planet carrier H of the differential control unit of the first and second planetary gear trains is connected with the outer ring of the first overrunning clutch as a whole, the speed n H Less than the inner ring speed n connected with the right drive half shaft 2 , so the first overrunning clutch is in an overrunning disengagement state; the inner sun gear 6 of the differential control unit of the second planetary gear train is connected with the outer ring of the second overrunning clutch, and the speed of the outer ring is n 6 Greater than the inner ring speed n connected with the right drive half shaft 2 , so the second overrunning clutch is also in the overrunning disengagement state, and the car runs normally.

[0079] When the car turns left with a radius greater than or equal to the minimum turning radius, n 1 ≥0.7n 0 , n 2 ≤1.3n 0 , at this time, the rotational speed n of the outer ring of the first overrunning clutch of the differential control unit of the first planetary gear train H =0.7n 0 Less than or equal to the speed n of the inner ring 2 , the first overrunning clutch is in the overrunning disengagement state or the inner and outer rings rotate at the same speed, which does not affect the right drive half shaft n 2 at the same time, the outer ring speed n of the second overrunning clutch of the second planetary gear differential control unit 6 =1.3n 0 Greater than or equal to the speed n of the inner ring 2 , the second overrunning clutch is also in the overrunning disengagement state or the inner and outer rings rotate at the same speed, which does not affect the right drive half shaft n 2 rpm, the car makes a left turn at normal differential speed.

[0080] When the car turns right with greater than or equal to the minimum turning radius, n 1 ≤1.3n 0 , n 2 ≥0.7n 0 , at this time, the rotational speed n of the outer ring of the first overrunning clutch of the differential control unit of the first planetary gear train H =0.7n 0 Less than or equal to the speed n of the inner ring 2 , the first overrunning clutch is in the overrunning disengagement state or the inner and outer rings rotate at the same speed, which does not affect the right drive half shaft n 2 at the same time, the outer ring speed n of the second overrunning clutch of the second planetary gear differential control unit 6 =1.3n 0 Greater than or equal to the speed n of the inner ring 2 , the second overrunning clutch is in the overrunning disengagement state or the inner and outer rings rotate at the same speed, which does not affect the right drive half shaft n 2 rpm, the car turns right at the normal differential speed.

[0081] Assuming that the left wheel of the car slips and exceeds the normal differential range, that is, when n 11.3n 0 , because n 1 +n 2 =2n 0 , then there must be n 2 <0.7n 0 , the speed n of the outer ring of the first overrunning clutch of the differential control unit of the first planetary gear train H =0.7n 0 Greater than the speed n of the inner ring 2 , the first overrunning clutch is in engagement, so that the right half shaft n 2 The speed cannot be lower than n H =0.7n 0 RPM, limited n 1 The speed of the second planetary gear train continues to increase, so as to achieve the purpose of limiting slip and ensure the normal driving of the vehicle; at the same time, the speed n of the outer ring of the second overrunning clutch of the second planetary gear system differential control unit 6 =1.3n 0 Greater than the speed n of the inner ring 2 , the second overrunning clutch is in the overrunning disengagement state and does not affect the right half shaft n 2 speed.

[0082] Suppose the right wheel of the car slips, when n 21.3n 0 , the rotational speed n of the outer ring of the first overrunning clutch of the differential control unit of the first planetary gear train H =0.7n 0 less than the speed n of the inner ring 2 , the first overrunning clutch is in the state of overrunning and disengagement, which does not affect the speed of the right half shaft; at the same time, the outer ring speed n of the second overrunning clutch of the second planetary gear system differential control unit 6 =1.3n 0 less than the speed n of the inner ring 2 , the second overrunning clutch is engaged, thereby limiting the right drive axle n 2 The rotational speed of the motor continues to increase, which achieves the purpose of limiting slip and ensures the normal driving of the vehicle.

[0083] To sum up, no matter the left and right wheels are driving straight, the minimum turning radius of the left and right or the slipping state, the differential controller of the planetary gear train can not only meet the maximum differential requirement of the minimum turning radius of the left and right wheels, but also can meet the requirements of the maximum differential speed when the vehicle is about to exceed the minimum turning radius of the left and right wheels. The normal differential speed will automatically limit the slip in time when slippage occurs, so as to ensure the normal driving of the vehicle.

[0084] Further, the change curve of the left and right wheel speed is as follows: image 3 shown; from image 3 It can be seen that when the wheel speed is within the set upper and lower threshold range (1-k)n 0 ———(1+k)n 0 When the differential speed of the wheel is normal, the minimum turning radius requirement is met; when the wheel slip exceeds the upper and lower threshold range, the first overrunning clutch and the second overrunning clutch limit the right wheel speed n H ≤n 2 ≤n 6 , or (1-k)n 0 ≤n 2 ≤(1+k)n 0 , so as to achieve the purpose of limiting slip, so that the vehicle can automatically skid, get out of trouble in time, and pass normally.

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