JPH09280338A - Differential device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a differential device having a differential limit function and facilitating miniaturization and lightening of weight. SOLUTION: A plurality of pinion gears 13 engaged with a sun gear 14 and a ring gear 15 are arranged between the sun gear 14 and the ring gear 15. A planetary carrier 11 having a plurality of pinion gears 13 connected thereto is arranged and then the planetary carrier 11 is provided with an arcuate pinion gear holding surface 11D to which a tooth end surface of the pinion gear 13 is abutted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a differential device used in a torque transmission mechanism of a vehicle, more specifically,
The present invention relates to a torque sensitive differential device having a differential limiting function.

[0002]

2. Description of the Related Art A four-wheel drive vehicle is widely used in which torque output from an engine via a transmission is distributed to front and rear four wheels to improve running performance on rough terrain. In view of the fact that the torque distribution ratio to the wheels has a great influence on the turning performance and the steering stability, the torque distribution ratio to the front and rear wheels is gradually changed according to the running state of the vehicle. The change of the torque distribution ratio is executed by limiting the differential in the center differential (central differential device) that performs the differential between the front and rear wheels, for example, by transmitting a part of the torque on the rear wheel side to the front wheel side. Has been done.

An example of a device therefor is disclosed in Japanese Patent Laid-Open No. 7-18.
No. 6768. The differential device described in this publication is configured such that a gear is a helical gear and a friction torque is generated by a thrust force generated at a meshing surface thereof. Specifically, the sun gear of the planetary gear mechanism that forms the center differential is integrated with an output gear that is arranged adjacent to the planetary gear mechanism, and the output gear and the planetary carrier are provided between the output gear and the output gear. A thrust washer is arranged between the casing and the casing of the adjacent viscous coupling, and the thrust washer is slidably rotated by the thrust force generated by torque transmission by the planetary gear mechanism. It is designed to enforce restrictions. Further, the viscous coupling is provided between the output gear and a member to which torque is transmitted from the planetary carrier, and when differential rotation occurs in the planetary gear mechanism, a torque due to shearing of a viscous fluid is generated. Occurs, which limits the differential.

[0004]

As described above, the differential device has one input member and two output members, and operates so that the average value of the rotation speed of the output member becomes the input rotation speed. Is configured to allow differential rotation between the output members, and in the past, in general, the planetary gear mechanism described above and a pair of side gears arranged on the same axis line between them are provided between them. A differential gear or the like that transmits torque by the arranged pinion is used. Since the differential action is performed by relative rotation between the constituent elements, the differential limitation is achieved by providing the friction member such as the thrust washer or the viscous coupling described above between any two elements. Has been done.

Since the friction member generates a frictional force by rotation, it is arranged on the same axis as the differential gear such as the planetary gear mechanism. Therefore, in the conventional device, the means for limiting the differential is additionally arranged in line in the axial direction, so that at least the dimension in the axial direction must be increased, and in the end, the size of the device is large. There was an inconvenience that caused the change.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a differential device having a differential limiting function, which is easy to reduce in size and weight.

[0007]

To achieve the above object, the invention of claim 1 is a sun gear which is an external gear, and an internal gear which is arranged concentrically with the sun gear. A planetary carrier comprising: a ring gear; a pinion gear arranged between the sun gear and the ring gear for transmitting torque between the sun gear and the ring gear; and a planetary carrier that holds the pinion gear so that it can revolve and rotate about the planetary carrier. A tubular accommodating portion oriented in the axial direction is formed in the accommodating portion, the pinion gear is rotatably accommodated in the accommodating portion, and the tooth tip surface of the pinion gear is slidably contacted with the inner peripheral surface of the accommodating portion. It is characterized by being held.

According to a second aspect of the present invention, in addition to the structure of the first aspect, the planetary carrier is moved in the radial direction by a circumferential load and slidably contacts the tooth crests of the sun gear or ring gear. It is characterized by having.

Therefore, in the structure of claim 1, when the differential rotation does not occur, the entire body rotates integrally, so that there is no relative operation between the pinion gear and the planetary carrier, and there is friction sliding. The differential limiting force due to does not occur. On the other hand, when a differential rotation occurs between any two elements, that is, when a differential action is performed, the pinion gear rotates on its axis, so that the tooth crests of the pinion slide against the inner surface of the accommodation portion of the planetary carrier. The friction torque generated therewith acts as the differential limiting torque. That is, according to the first aspect of the invention, the pinion gear is rotatably housed in the housing part of the planetary carrier, so that the sliding generated between the pinion gear and the planetary carrier acts as a differential limiting action, and the members constituting the differential device are provided. The differential limitation can be performed without requiring an additional member, and the differential device having the differential limitation function can be downsized.

According to the second aspect of the present invention, the differential action causes the planetary carrier to rotate relative to the sun gear or the ring gear, causing the sun gear or the planetary carrier to slide, and the frictional force thereof serves as the differential limiting torque. To work.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the present invention will be described based on specific examples. The differential device shown in FIG. 1 includes a ring gear 15 which is an internal gear, a sun gear 14 which is an external gear arranged concentrically inside the ring gear 15, and a plurality of gears which are meshed with the ring gear 15 and the sun gear 14. 1 is a planetary gear type having a pinion gear 13 and a planetary carrier 11 that supports these pinion gears 13.

The planetary carrier 11 is set to have an outer diameter substantially the same as the outer diameter of the ring gear 15, and the shaft hole 1
It is composed of a pair of annular end plates 12 having 2A and three blocks 11A provided between the pair of end plates 12. These three blocks 11A are arranged on the same circumference of the end plate 12 at intervals of approximately 120 degrees and project from the side surface of the end plate 12 in the axial direction. In this embodiment,
The one end plate 12 and the three blocks 11A are integrally formed, and the other end plate 12 and the three blocks 11A are fixed by screws (not shown) or the like.

The three blocks 11A are formed in the same shape, and arcuate surfaces 11B having substantially the same curvature are separately formed on their outer circumferences. The diameter of the circle formed by connecting the circular arc surfaces 11B is equal to the ring gear 1
It is set smaller than the inner diameter of 5. In addition, inside the three blocks 11A, curved toward the outside,
Also, the sun gear holding surface 11C set to have substantially the same curvature
Are formed respectively. And the sun gear holding surface 1
The diameter of the circle formed by connecting the 1Cs is 1
It is set larger than the outer diameter of No. 4.

Further, the portions of the three blocks 11A facing each other in the circumferential direction are curved in a concave shape (concave shape),
Moreover, the pinion gear holding surface 1 having substantially the same curvature is set.
1D is formed separately. The diameter of the circle formed by connecting the opposing pinion gear holding surfaces 11D is set to be substantially equal to the outer diameter of the pinion gear 13. That is, the pinion gear holding surfaces 11D facing each other
Form a cylindrical pinion gear accommodating portion that is cut open at the inner peripheral side and the outer peripheral side of the end plate 12 in the radial direction.

In the differential device configured as described above, the planetary carrier 11 is rotatably arranged inside the ring gear 15, the sun gear 14 is arranged in the space between the sun gear holding surfaces 11C, and the opposed pinion gears are arranged. Holding surface 1
The pinion gears 13 are arranged in the spaces between the 1Ds.

FIG. 2 shows an assembled state of the sun gear 14, the ring gear 15, the pinion gear 13 and the planetary carrier 11, which are the rotating elements of the above-mentioned differential device, in which the sun gear 14 and the ring gear 15 are arranged concentrically. The block 11A of the planetary carrier 11 is inserted between the gears 14 and 15 from one end side in the axial direction. Then, the pinion gear 13 is inserted into each of the housing portions formed in the block 11A, that is, the cylindrical portion formed by the pinion gear holding surface 11D. In this state, each pinion gear 13 projects outward from the cutout portion of the accommodation portion, and meshes with the sun gear 14 and the ring gear 15 at the projecting portion. Further, each pinion gear 13 is in contact with the pinion gear holding surface 11D holding it.

FIG. 3 is a skeleton diagram of a four-wheel drive system in which the above-mentioned differential device is formed as a center differential, in which an input shaft (an output shaft of a transmission (not shown)) 1 is connected to a planetary carrier 11. On the other hand, the sun gear 14 is connected to the front wheel output shaft 12 via the pair of sprockets 3B and the silent chain 3A,
Further, a ring gear 15 is connected to the rear wheel output shaft 4. Therefore, the torque of the input shaft 1 is
Is transmitted to the sun gear 14 and the ring gear 15 via the gears, but torque is generated based on the difference in the radius (pitch circle radius) from the rotation center of the meshing position of the pinion gear 13, the sun gear 14, and the ring gear 15. 15 and unequal distribution.

When there is no differential rotation between the front and rear wheels,
Since the entire differential device rotates as a unit, relative rotation does not occur between the rotating elements described above. On the other hand, when one of the front wheels or the rear wheels runs idle due to slippage or the like, differential rotation occurs between the front wheels and the rear wheels. The difference in rotation speed between the front and rear wheels is absorbed by the rotation of the pinion gear 13, but since the pinion gear 13 is in contact with the holding surface 11A of the pinion gear 13, a friction force is generated by the rotation of the pinion gear 13, and the frictional force is generated. The force acts as a differential limiting force. For example, as shown in FIG. 4, when the sun gear 14 rotates at a higher speed than the ring gear 15 in a differential state, the pinion gear 13 rotates in the direction indicated by the single-line arrow in FIG. 4, but the planetary carrier 11 rotates the pinion gear 13. A frictional force is generated according to the contact load due to the pressing, and the rotation of the pinion gear 13 is suppressed. That is, a differential torque is generated in a direction that suppresses the differential rotation between the sun gear 14 and the ring gear 15, and the torque distribution ratio based on the pitch circle radius between the sun gear 14 and the ring gear 15 becomes a distribution ratio changed according to the friction torque. .

If the gears 13, 14, 15 are helical gears, a thrust force is generated based on the torque transmission, and the gears 13, 14, 15 are pressed against the end plate 12. , A friction torque is generated at the contact surface. This friction torque is also generated in the direction in which the relative rotation of each element of the differential device is suppressed, so that the differential limitation of the front and rear wheels is performed.

Therefore, in the above-described differential device having the configuration shown in FIGS. 1 to 4, a friction torque based on the differential rotation is generated between the pinion gear 13 and the planetary carrier 11, which are the original components, and the friction torque is generated. Since the differential limitation is performed by the above, no special mechanism for differential limitation is required. Therefore, since there is no additional mechanism, the configuration is simplified,
It is advantageous for downsizing and weight reduction. In addition, the setting for the torque distribution ratio is
Since it can be freely set by the gear ratio (the ratio of the number of teeth of the sun gear to the number of teeth of the ring gear), it can be used as a differential device for the left and right wheels in addition to the center differential. Further, since the support rigidity of the pinion gear 13 is increased, it is possible to maintain good gear engagement accuracy and prevent noise generation. When used as a center differential, the pinion gear 13 is in contact with the holding surface 11A and functions to suppress the rotation of the pinion gear 13, so that the response delay of the differential limitation does not occur and the straight running stability is improved. Can be made.
Further, even when it is used as a differential device for the left and right wheels, a response delay due to differential limitation does not occur.

The present invention can also be configured as a double pinion type planetary gear mechanism. An example thereof is shown in FIG. 5, and between the sun gear 14 and the ring gear 15, pinion gears 13a and 13b meshing with each other are arranged. The pinion gear 13b on the outer peripheral side meshes with the ring gear 15, and the pinion gear 13b on the inner peripheral side meshes with the sun gear 14. Further, the planetary carrier 11 is provided with a plurality of blocks 11D divided in the circumferential direction, and the sun gear holding surface 11E curved in an arc shape is separately formed on the inner circumference of each block 11D, and The pinion gear holding surface 11 curved in an arc shape is provided on the circumferentially opposite surfaces of the block 11D.
F is formed. That is, the pinion gear holding surface 11F forms a housing portion for the pinion gears 13a and 13b.

Then, the planetary carrier 11 having the above structure
In the assembled state of, the pinion gear holding surface 11F
The tooth crests of the pinion gears 13a and 13b are in contact with. The differential limiting force of this differential device is the difference between the tooth tip surfaces of the pinion gears 13a and 13b and the pinion gear holding surface 11F.
The magnitude of the differential limiting force can be appropriately adjusted by changing the number and size of the pinion gears, the helical angle of the gears, etc. In this way, the same effect as that of the embodiment of FIGS. 1 to 4 can be obtained in the embodiment of FIG.

Another example of the present invention will be described with reference to FIG. In the example shown in FIG. 6, a cam mechanism is provided so as to generate a friction torque also on the sun gear 14 and the ring gear 15. That is, the planetary carrier 11 includes an inner piece 11G and an outer piece 11H that are divided into two in the radial direction and function as a cam follower.
A wedge-shaped center piece 11J that functions as a cam is fitted between 1G and the outer piece 11H.

An inner peripheral surface of the inner piece 11G is provided with a sun gear contact surface 11C curved in an arc shape, and arcuate shapes are formed at both circumferential ends of the inner piece 11G and the outer piece 11H. A pinion gear holding surface 11D that is curved to the left is formed. The tooth tip surface of the pinion gear 13 is brought into contact with the pinion gear holding surface 11D. Further, an inclined surface 11M is provided on the outer peripheral surface of the inner piece 11G, and an inclined surface 11N is provided on the inner peripheral surface of the outer piece 11H, the inclined surface 11M and the inclined surface 11N. A wedge shape is formed by. Further, a ring gear contact surface 11Z that contacts the tooth crest surface of the ring gear 15 is formed on the outer peripheral surface of the outer piece 11H.

The center piece 11J is fixedly integrated with the end plate shown in the above-mentioned example, while the inner piece 11G and the outer piece 11H are opposed to each other.
And are arranged between the ring gear 15 and the sun gear 14 so as to be movable in the radial direction. The inner piece 11G and the outer piece 11H may be movably attached to the end plate by appropriate means in order to avoid rattling noises and the like. Centerpiece 11J
Is formed into a substantially isosceles triangle, and the base 11
K is arranged so as to extend substantially in the radial direction. Also,
By the other inclined surface 11L of the center piece 11J, FIG.
It is formed in a wedge shape that tapers in the direction of rotation which is the arrow direction.

Therefore, the inclined surface 11L of the center piece 11J, which is the input side portion and acts as a cam, is the inclined surface 11M of the inner piece 11G, which is the output side portion and acts as a cam follower, and the outer piece 11.
It separately abuts the inclined surface 11N of H. Therefore, when torque in the arrow direction is applied to the center piece 11J from the input shaft, the center piece 11J presses the inner piece 11G and the outer piece 11H in the tangential direction which is the arrow direction in FIG. It presses against the pinion gear 13. At the same time, the inner piece 1 is divided by the radial component force due to the slope effect (that is, the wedge effect).
1G and the outer piece 11H are pressed in the radial direction,
The inner piece 11G is pressed against the outer peripheral surface of the sun gear 14, while the outer piece 11H is pressed against the inner peripheral surface of the ring gear 15. Therefore, a sliding frictional resistance force is generated on these contact surfaces, which acts so as to regulate the relative rotation of each rotary element, and the differential limitation is performed. in this way,
Also in the embodiment of FIG. 6, the same effect as that of the embodiment shown in FIGS. 1 to 4 can be obtained.

Further, when the direction of the torque acting on the center piece 11J is reversed, the wedge effect by the inclined surface 11L, that is, the effect of pressing the inner piece 11G against the sun gear 14 and the outer piece 11H.
Is not pressed against the ring gear 15, it is possible to make the differential limiting force different between forward movement and backward movement. Further, since the torque input directions are opposite during acceleration and during deceleration, the differential limiting force during deceleration can be made smaller than during acceleration, and compatibility with the antilock brake system can be improved.

FIG. 7 shows a modification of the configuration shown in FIG. 6, in which the planetary carrier 11 is provided with a piece 11P and a piece 11Q which are divided into two in the circumferential direction.
These pieces 11P and 11Q are inclined surfaces 11R and 11S inclined by a predetermined angle with respect to the radial direction of the ring gear 15.
Are separately provided, and the piece 11P is fixed to the end plate in the above-described example. On the other hand, the other piece 11Q is arranged between the ring gear 15 and the sun gear 14 so as to be movable at least in the radial direction. In order to prevent the rattling noise of the movable piece 11Q, it may be held appropriately on the end plate.

On the outer peripheral surface of the movable piece 11Q, the ring gear contact surface 11 that contacts the tooth crest surface of the ring gear 15 is formed.
Z is formed, and a pinion gear holding surface 11D that comes into contact with the tooth crest surface of the pinion gear 13 is formed on the circumferential end surface of the movable piece 11Q.

When a torque in the direction of the arrow (clockwise in the figure) is applied to the piece 11P from the input shaft, the differential device of the above construction pushes the piece 11Q clockwise so that its pinion gear holding surface is the pinion gear 13. While being pressed against the tooth tip surface of the ring gear 15, the piece 11Q is moved to the outer peripheral side by the repulsive force between the inclined surface 11R and the inclined surface 11S, and the outer peripheral surface of the piece 11Q is brought into contact with the tooth tip surface of the ring gear 15. Differential limiting force is generated by the resistance. Thus, also in the embodiment shown in FIG. 7, the same effect as that of the embodiment shown in FIGS. 1 to 4 can be obtained.

Further, in the example shown in FIG. 7, when the torque in the opposite direction is applied to the piece 11P, the differential restriction is performed by the frictional resistance due to the contact between the tooth top surface of the pinion gear 13 and the pinion gear holding surface 11D. Since a force is generated and a frictional resistance with the ring gear 15 is not generated, the differential limiting force generated is different from the above case. That is, the compatibility with the anti-lock brake system is good as in the example shown in FIG.

The present invention is not limited to the above-described embodiments, and the number of pinion gears may be two or four or more, and when the differential rotation occurs, the sun gear or the ring gear may be used. As the cam mechanism for generating or increasing the sliding frictional force with the planetary carrier, other than the one utilizing the inclined surface effect or the wedge effect described above, an appropriate structure can be adopted as necessary. The point is that the torque may be converted into a radial force to increase the contact pressure between the rotating elements.

[0033]

As described above, according to the invention described in claim 1, the differential limitation is performed by the frictional resistance between the pinion gear holding surface of the planetary carrier and the tooth top surface of the pinion gear, and the planetary carrier is Since it is an original component provided in advance in the planetary gear mechanism type differential device, no special component for limiting the differential is required, the number of components and the number of assembly steps can be suppressed, and the device can be downsized. Manufacturing cost can be suppressed.

According to the second aspect of the present invention,
In addition to the same effect as in claim 1, the contact pressure between the sun gear or the ring gear is increased by the cam mechanism, and sliding resistance due to the differential rotation is generated between these gears, which is more effective. Differential limitation can be performed.

[Brief description of drawings]

FIG. 1 is a perspective view showing a differential device of an example of the present invention in an exploded state.

FIG. 2 is a schematic sectional view showing a part of the differential device in an assembled state.

FIG. 3 is a skeleton diagram of an example in which the differential device is incorporated as a differential device in a four-wheel drive system.

FIG. 4 is a schematic diagram for explaining a differential limited state by the planetary carrier and a pinion gear.

FIG. 5 is a partial schematic sectional view showing an example in which the present invention is applied to a double pinion type planetary gear mechanism.

FIG. 6 is a schematic cross-sectional view showing the main parts of another example of the present invention.

FIG. 7 is a schematic cross-sectional view of the main parts showing a further modified example of the example shown in FIG.

[Explanation of symbols]

 14 Sun gear 15 Ring gear 13, 13a, 13b Pinion gear 11 Planetary carrier 1 Input shaft 4 Axle shaft 11D, 11F Pinion gear holding surface 11J Center piece 11P piece 11G Inner piece 11H Outer piece 11Q piece 11L, 11M, 11N, 11R, 11S Inclined surface

Claims (2)

[Claims] 1. A sun gear which is an external gear, and a ring gear which is an internal gear arranged concentrically with the sun gear,
In a differential device including a pinion gear that is arranged between these sun gear and ring gear and transmits torque between the sun gear and ring gear, and a planetary carrier that holds the pinion gear so that it can revolve and rotate, A tubular accommodating portion oriented in the axial direction is formed, the pinion gear is rotatably accommodated in the accommodating portion, and the pinion gear is held in a state of slidingly contacting the tooth crest surface with the inner peripheral surface of the accommodating portion. A differential device characterized in that 2. The planetary carrier is provided with a cam mechanism that moves in a radial direction by a load in a circumferential direction and is brought into sliding contact with a tooth tip surface of the sun gear or the ring gear. Differential.