JPH06137386A - Differential limiting type differential gear - Google Patents

Abstract

PURPOSE:To provide a differential limiting type differential gear capable of distributing torque unequally with simple structure while being provided with differential limiting function. CONSTITUTION:A differential limiting type differential gear 1 has a case 2 rotated integrally with an input gear 4, and a pair of side gears 10, 11 and plural pinion gears 18..., 19... rotatably supported with the outer peripheral parts thereof supported at the case 2. The side gears 10, 11 are fitted to the mutually opposed end parts of a pair of transmission shafts 6, 7. The pinion gears 18..., 19... are meshed with the side gears 10, 11, and the pinion gears 18, 19 are meshed with each other. The side gears 10, 11 are formed of helical gears different in diameter and the number of teeth. The torque transmitted to the transmission shafts 6, 7 is distributed unequally in proportion to the diameters of the side gears 10, 11. The efficiency of this differential gear 1 is suppressed low, and as a result, the differential gear 1 displays its differential limiting function.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a differential limited type differential device.

[0002]

2. Description of the Related Art In a general differential device used for a wheel drive system of a vehicle such as an automobile, for example, torque distribution is always equal to the left and right drive wheels. When the differential device is used as a center differential of a four-wheel drive vehicle (hereinafter referred to as a 4WD vehicle), torque from the engine is equally distributed to the front wheels and the rear wheels.

However, in a special vehicle that turns in a certain direction in agricultural work or the like, even torque distribution to the left and right wheels is not always rational. Even in a 4WD vehicle, even torque distribution to the front and rear wheels is not rational, and the torque distribution should be made uneven according to the weight distribution in the front-rear direction of the vehicle body.

Therefore, a method using electronic control or a method in which the diameters (differential ratios) of a pair of differential gears are made different (Japanese Patent Laid-Open No. HEI 2)
-220929), an attempt has been made to make the torque distribution uneven.

On the other hand, the total driving force of the vehicle is twice the driving force of the driving wheel having the smaller frictional force (when the efficiency of the differential device is 100%), and one driving wheel (left wheel, right wheel or If the driving force decreases due to slippage or idling of either the front or rear wheel), the driving force of the other driving wheel also decreases, and the vehicle may become stuck.

A differential limiting device (differential lock) has been proposed in order to solve the above problem, but as such a device, a method of generating a friction torque (Japanese Patent Publication No. 46-3407).
(See Japanese Patent Laid-Open Publication No. 2001), a system using a mechanical clutch mechanism is known.

[0007]

However, among the above-mentioned methods for making the torque distribution uneven, the electronically controlled method has a drawback that the structure becomes plural and the cost is increased, and the diameters of the pair of differential gears ( The method of making the differential ratios different from each other has a problem that the pinion gear is not assembled or its rigidity is problematic and that it does not have a differential limiting function.

Further, particularly in the differential limited type (spin limited type) differential device disclosed in Japanese Patent Publication No. 46-3407, since the pair of side gear diameters (differential ratios) are equal, the torque is uneven. It has a drawback that it cannot be applied to a center differential of a vehicle that needs to be distributed (particularly a 4WD vehicle).

The present invention has been made in view of the above problems, and an object of the present invention is to provide a differential limiting type differential which is capable of uneven torque distribution with a simple structure and also has a differential limiting function. To provide a moving device.

[0010]

In order to achieve the above object, the present invention provides a case that rotates integrally with an input gear, a pair of side gears whose outer peripheral portions are supported by the case and is rotatably supported. A pinion gear is provided, and the side gears are fitted to opposite ends of a pair of transmission shafts, the side gears are meshed with the pinion gears, and pinion gears meshed with the side gears are meshed with each other. The motion limiting type differential device is characterized in that the pair of side gears are helical gears having large and small diameters and different numbers of teeth.

[0011]

According to the present invention, the rotational power input to the input gear is transmitted to the pair of transmission shafts via the case, the pinion gear and the side gear, respectively. However, since the pair of side gears have different diameters (number of teeth), Torque distribution is unevenly distributed on both transmission shafts. Specifically, since a large torque is transmitted to the transmission shaft on the side gear side having a large diameter, for example, in a 4WD vehicle using the differential device as a center differential, transmitting a large torque to the rear wheel side having a large weight. Is possible.

Further, in the differential limited type differential device according to the present invention, the side gear and the pinion gear are supported at their outer peripheral portions by the case, and the side gear is composed of the helical gears. A large frictional force is generated between the case and the case, and the efficiency (power transmission efficiency) of the differential device is suppressed to be low. However, the total driving force when one of the driving wheels slips depends on the torque applied to the driving wheel that is slipping and the efficiency of the differential device. The force becomes large (for example, when the efficiency is 100%, the total driving force is twice the driving force of the drive wheels in which the slip occurs, whereas when the efficiency becomes 50%, the total driving force causes the slip. It is three times the driving force of the driving wheel).

Therefore, as described above, the differential device according to the present invention whose efficiency is kept low can perform the differential limiting function with a simple structure.

[0014]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a sectional view of a differential limited type differential device 1 according to a first embodiment of the present invention, and FIG. 2 is a sectional view taken along line AA of FIG.

The differential limited type differential device 1 according to this embodiment has four
It is used as a center differential of a WD vehicle, and has a case 2 which is divided into two parts in the front and rear (the left side in FIG. 1 is the vehicle front side and the right side is the vehicle rear side).

That is, in the case 2, the front half 2A and the rear half 2B are joined and integrated by a plurality of bolts 3 (see FIG. 2), and the flange 2B-1 of the rear half 2B has a ring shape. The input gear 4 is bound by a plurality of bolts 5 ... The input gear 4 receives rotational power from an engine (not shown).

Further, in the front half 2A and the rear half 2B of the case 2, the respective ends of transmission shafts (propeller shafts) 6, 7 coaxially arranged in the longitudinal direction of the vehicle body are freely rotatable by metal bearings 8, 9. A small-diameter side gear 10 and a large-diameter side gear 11 are connected to each end of the transmission shafts 6 and 7 facing the case 2 by spline fitting. The side gears 10 and 11 are fitted in the recessed grooves 12 and 13 formed in the front half 2A and the rear half 2B of the case 2, respectively, and the outer peripheral portions of the side gears 10 and 11 are recessed.
Each is rotatably supported by. The side gears 10 and 11 are composed of helical gears whose modules have the same number of teeth, and their helical teeth have the same twist angle.
The twist directions are set opposite to each other.

Further, the both side gears 1 in the case 2 are
A substantially ring-shaped spacer 14 is interposed between 0 and 11, and pressing members 15 and 16 divided into two parts in the front and rear are spline-fitted in the inner peripheral portion of the spacer 14 so as to be movable in the front-rear direction. Has been done. The pressing members 15 and 16 are urged in opposite directions by a plurality of disc springs 17 incorporated therein to press the side gears 10 and 11 toward the case 2.

On the other hand, each of the four pinion gears 18 ..., 19 ... which are in mesh with the side gears 10, 11 and are long in the front-rear direction are rotatably housed in the case 2 at an equal angular pitch, as shown in FIG. Thus, the pinion gears 18 and 19 are in mesh with each other. Note that the pinion gears 18, ..., 19 are composed of helical gears, and these are formed in the case 2 with concave grooves 20 ..., 2 having a notched circular cross section.
1, ..., 22 ...
It is rotatably supported by 0, 21, 22.

Next, the differential limited type differential device 1 according to the present invention.
The action of will be explained.

As described above, when the rotational power from the engine (not shown) is input to the input gear 4 of the differential device 1, the case 2 rotates around the shaft centers of both transmission shafts 6 and 7, and this case By the rotation of 2, the two pinion gears 18 ..., 19 ... Revolve about their own shaft centers while revolving about their respective shaft centers of the transmission shafts 6, 7, and transmit rotational power to the side gears 10, 11, respectively. Then, the side gears 10 and 11 and the transmission shafts 6 and 7 are rotationally driven, and the torque T input from the engine to the input gear 4 is divided into T1 and T2, which are transmitted through the transmission shafts 6 and 7, respectively, to the front wheel side and the rear wheel. The front and rear wheels (not shown) are simultaneously driven to drive the 4WD vehicle.

Here, the distribution T1 / T2 of the torque T to the front wheel side and the rear wheel side will be considered.

The pitch circle radii of the side gears 10 and 11 are r1 and r2 (r1 <r2), respectively, as shown in the figure, and the tangential components of the transmission force generated at the meshing points of the side gears 10 and 11 and the pinion gears 18 and 19, respectively. Assuming F1 and F2, the transmission torques T1 and T2 to the front wheel side and the rear wheel side are respectively expressed by the following equations.

[0025]

## EQU1 ## T1 = F1 × r1 (1) T2 = F2 × r2 (2) However, when the differential limiting function does not work,

[0026]

Since F1 = F2 (3), the following equation is obtained from the equations (1) and (2).

[0027]

[Formula 3] T1 / T2 = r1 / r2 (4) From the above formula (4), the transmission torques T1 and T2 are the side gear 1
It can be seen that the pitch circle radii of 0 and 11 are proportional to r1 and r2.

Thus, in the present embodiment, the diameter r2 of the side gear 11 contributing to the power transmission to the rear wheel side, which has a large weight, is larger than the diameter r1 of the side gear 10 contributing to the power transmission to the front wheel side (r2. > R1) Since it is set, the following equation holds,

[0029]

[Equation 4] T2 = T1 × r2 / r1> T1 (5) (∵r2 / r1> 1) The transmission torque T2 to the rear wheel side becomes larger than the transmission torque T1 to the front wheel side, and the vehicle body Reasonable torque distribution according to the weight distribution in the front-rear direction becomes possible.

Next, considering the case where, for example, a front wheel enters a muddy ground or the like and slips occur in this, the transmission torque T1 to the front wheel side is given by the following equation, where e is the efficiency of the differential 1 It is represented by.

[0031]

## EQU00005 ## T1 = e.times.T2.times.r1 / r2 (6) Here, assuming that the radii of the front and rear wheels are R, the total driving force F of the front and rear wheels is expressed by the following equation.

[0032]

## EQU6 ## F = (T1 + T2) / R (7) Then, from the equation (6), T2 is expressed as follows.

[0033]

## EQU00007 ## T2 = T1.times. (1 / e) .times. (R2 / r1) (8) Substituting equation (7) into equation (8) above gives total driving force F
Can be rewritten as

[0034]

[Equation 8] F = T1 × (1+ (1 / e) × (r2 / r1)) / R (9) In the above equation (9), the total driving force F is applied to the front wheel side where slip occurs. It shows that it depends on the applied torque T1 and the efficiency e of the differential 1. When the rear wheels are slipping, the total driving force F depends on the torque T2 applied to the rear wheels and the efficiency e of the differential device 1.

Therefore, the efficiency e of the differential 1 is 100%.
When (1.0), 90% (0.9), and 50% (0.5), the total driving force F is the result expressed by the following equation from the equation (9).

[0036]

F = (1 + r2 / r1) × T1 / R (e = 100%) (10) F = (1 + 1.1r2 / r1) × T1 / R (e = 90%) (11) F = (1 + 2r2 / r1) × T1 / R (e = 50%) (12) From the above equations (10) to (12), the lower the efficiency e of the differential gear 1, the larger the total driving force F. I see.

In the limited slip differential type differential device 1 according to this embodiment, the side gears 10, 11 and the pinion gears 18, ..., 19 ...
Moreover, since the side gears 10, 11 are helical gears, a large frictional force is generated between the side gears 10, 11 and the pinion gears 18, ...
The efficiency e of the differential device 1 can be kept low.

Therefore, according to the differential device 1 of this embodiment, even if the front wheels (or the rear wheels) slip,
A large total driving force F can be generated, and the differential device 1 can exhibit the differential limiting function with a simple configuration.

Next, a second embodiment of the present invention is shown in FIG.
Note that FIG. 3 is a view similar to FIG. 2 according to the second embodiment, and in this figure, the same elements as those shown in FIG.

The basic structure of the differential limited type differential device 1 according to the present embodiment is the same as that of the first embodiment, but in this embodiment, the number of pinion gears 18 ...
12 in total, and adjacent pinion gears 18 and 19
Engage each other.

Thus, in this embodiment, the same effect as that of the first embodiment can be obtained, but the efficiency of the differential 1 can be further lowered by increasing the number of pinion gears as described above. Even if the front wheel or the rear wheel slips, a larger total driving force can be generated.

[0042]

As is apparent from the above description, according to the present invention, a case which rotates integrally with an input gear, a pair of side gears whose outer peripheral portion is supported by the case and which is rotatably supported, and a plurality of side gears. A pinion gear is provided, and the side gears are fitted to opposite ends of a pair of transmission shafts, the side gears are meshed with the pinion gears, and pinion gears meshed with the side gears are meshed with each other. In the motion limiting type differential device, since the pair of side gears are composed of helical gears having large and small diameters and different numbers of teeth, the differential device enables uneven torque distribution with a simple structure, The effect that the differential limiting function can also be exerted is obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a differential limited type differential device according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a view similar to FIG. 2 of a differential limited type differential device according to a second embodiment of the present invention.

[Explanation of symbols]

 1 Differential limited differential device 2 Case 4 Input gear 6,7 Transmission shaft (propeller shaft) 10,11 Side gear 18,19 Pinion gear

Claims (1)

[Claims] 1. A case which rotates integrally with an input gear, a pair of side gears whose outer peripheral portion is supported by the case and which is rotatably supported, and a plurality of pinion gears, wherein the side gears are arranged relative to a pair of transmission shafts. Fit to each facing end,
In the differential limiting type differential device configured to mesh the pinion gear with the side gear, and to mesh the pinion gears meshing with each side gear with each other,
A differential limited type differential device, characterized in that the pair of side gears are helical gears having large and small diameters and different numbers of teeth.