JP2002031210A - Differential gear - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent seizure and galling by drastically reducing traveling resistance and drag torque on the disconnection side when driving force is shut off. SOLUTION: This differential gear is provided with a clutch device 13 for connecting and disconnecting a ring gear 5 meshed with a speed reduction gear 21 of a speed reduction mechanism 3 and a differential case 7 arranged coaxially with it, and a differential mechanism 11 for distributing driving force input from the clutch device 13 to the differential case 7 to the wheel side. Bearings 9, 9 are arranged between the ring gear 5 and the differential case 7, and the ring gear 5, the bearings 9, 9 and the differential case 7 are axially and coaxially overlapped and arranged.

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 for a four-wheel drive vehicle or the like, and more particularly to a differential device arranged on a drive wheel side where a driving force is cut off during two-wheel drive.

[0002]

2. Description of the Related Art A power transmission device 201 as shown in FIG. 2 is described in Japanese Patent Application Laid-Open No. 3-118233.

[0003] This power transmission device 201 is a differential device arranged on the front wheel side of a four-wheel drive vehicle that separates the front wheels to make a two-wheel drive state.
3. Inner case 205, multiple disc clutch 207 for intermittent driving force, hydraulic actuator 20 for fastening this
9, differential mechanism 211 of bevel gear type, multi-plate clutch 213 for limiting differential, hydraulic actuator 2 for fastening this
15 and the like.

[0004] The power transmission device 201 is a differential carrier 217.
The outer case 203 includes left and right boss portions 219 and 221 with thrust bearings 223 and 223.
By the differential carrier 217.

The drive pinion shaft 225 is connected to a transfer via a propeller shaft (not shown) on the front wheel side. A drive pinion gear 227 formed at the front end of the drive pinion shaft 225 is connected to a ring gear 229 fixed to the outer case 203. The outer case 203 is rotated by the driving force of the engine.

The inner case 205 is the outer case 2
03 is slidably supported on the inner periphery.

[0007] The multiple disc clutch 207 for intermittent driving force is connected to the outer case 2 of the left boss portion 219 of the outer case 203.
The inner case 205 is disposed between the inner boss 219 a protruding inside the inner case 205 and the inner case 205.
Is transmitted to the inner case 205.

The left side gear 231 of the differential mechanism 211 is connected to the drive shaft 233 on the left front wheel side, and the right side gear 235 is connected to the drive shaft 237 on the right front wheel side.
It is connected to. Each drive shaft 233, 237
Are supported while sliding on the inner periphery of the bosses 219 and 221 of the outer case 203.

The multi-plate clutch 213 for limiting the differential is arranged between the right front wheel side drive shaft 237 and the inner case 205, and when pressed by the hydraulic actuator 215, limits the differential of the differential mechanism 211. I do.

As described above, when the multi-plate clutch 207 is engaged, the inner case 205 is rotated by the driving force of the engine, and this rotation is distributed from the differential mechanism 211 to the left and right front wheels via the drive shafts 233 and 237. Thus, the vehicle enters the four-wheel drive state. At this time, when the multi-plate clutch 213 is engaged, the differential of the front wheels is limited.

On the other hand, when the connection of the multi-plate clutch 207 is released, the parts from the inner case 205 to the left and right front wheels are disconnected from the engine, and the vehicle is brought into a two-wheel drive state.

During the two-wheel drive travel, the front wheels rotate together, so that sliding occurs between the inner case 205 and the outer case 203, and the drive shaft 233,
Sliding occurs between the boss 237 and the bosses 219 and 221.

Oil is sealed inside the outer case 203 to lubricate these sliding parts, the differential mechanism 211, the multi-plate clutches 207 and 213, and the like.

[0014]

However, in the power transmitting device 201, the inner case 205 and the outer case 203, the drive shafts 233 and 237, and the boss portions 219 and 221 that slide during the two-wheel drive running of the vehicle are supported by bearings. Therefore, there is a possibility that sliding resistance is generated because each slides directly without intervening.

In addition, a four-wheel drive vehicle travels in a two-wheel drive state such as when traveling on a pavement road, so that it takes much longer to travel in a two-wheel drive state than to travel in a four-wheel drive state. These sliding surfaces are heavy,
Seizure and galling may occur, and the lubrication of the sliding surface must be considered.

Outer case 203 and inner case 2
If seizure or galling occurs during the period of 05, these are locked and the function of separating the front wheels is lost, and the drive system on the front wheel side is rotated, resulting in running resistance and reduced fuel consumption of the engine.

If seizure or galling occurs between the drive shafts 233 and 237 and the bosses 219 and 221, both the rotation of the front wheels and the differential rotation between the left and right wheels are locked. The dynamic function is lost, which affects the turning performance and the steering performance.

In order to solve such a problem, in order to sufficiently lubricate the sliding surfaces of the drive shafts 233 and 237 and the bosses 219 and 221, it is necessary to increase the oil level accordingly. If the amount of oil is large, oil leaks out when the seal is broken, which is disadvantageous in terms of failure mode.

The sliding resistance of the inner case 205, the outer case 203, the drive shafts 233, 237 and the bosses 219, 221 is a drag torque (drag torque).

The oil sealed in the outer case 203 is agitated by rotating members such as the gears of the inner case 205 and the differential mechanism 211 and becomes rotational resistance. The rotational resistance increases as the amount of oil increases. There was also a problem that would.

Further, the rotational resistance becomes a drag torque, and is added to the drag torque due to the above-described sliding resistance, and becomes a large drag torque.

When such a drag torque is generated, a driving force of a magnitude corresponding to the drag torque is transmitted to the drive system on the front wheel side, and a complete two-wheel drive state is not attained. In addition to the decrease, there is a possibility that the turning performance and turning performance of the vehicle may be affected.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a differential device which greatly reduces the rotational resistance and drag torque when the driving force is cut off, and prevents image sticking and galling.

[0024]

According to a first aspect of the present invention, there is provided a differential device comprising a plurality of pairs of reduction gears whose rotation axes are arranged in parallel or perpendicular to each other, and which reduces the rotation of a driving force source. A differential gear having a mechanism, a ring gear meshing with a reduction gear of the reduction mechanism, a differential case coaxially arranged with the ring gear, a clutch device for intermittently connecting between the ring gear and the differential case, and A differential mechanism that distributes the rotation of the driving force source input to the differential case to the wheel side, and a bearing that supports each other is arranged between the ring gear and the differential case, and the ring gear, the bearing, and the differential case are coaxially arranged. And are arranged so as to be wrapped in the axial direction.

As described above, the differential device having the clutch device for inputting the driving force decelerated by the speed reduction mechanism and intermitting the driving force is provided in the drive device in which the driving force is cut off during the two-wheel drive of the four-wheel drive vehicle. Used on the wheel side.

The clutch device intermittently connects the ring gear and the differential case. When the clutch device is connected, the driving force decelerated by the speed reduction mechanism rotates the differential case from the ring gear via the clutch device, and is transmitted to the wheel side by the differential mechanism. And the vehicle is in a four-wheel drive state.

When the coupling of the clutch device is released, the wheels from the differential case are separated from each other, and the vehicle enters a two-wheel drive state, and the ring gear and the differential case rotate relative to each other via a bearing.

Further, in the differential device of the first aspect, since the bearing is disposed between the ring gear and the differential case, the ring gear and the differential case do not slide directly in the two-wheel drive state in which the coupling of the clutch device is released. ,
Rotational resistance (running resistance) is extremely small.

Since the ring gear, the bearing and the differential case are arranged on the same axis and wrapped in the axial direction, the meshing reaction force of the ring gear can be supported by the bearing. No sliding resistance occurs between the bearings, and seizure and galling can be prevented by the bearing.

As described above, since sliding does not occur between the ring gear and the differential case and in the drive portion of the drive shaft in the two-wheel drive state, the occurrence of large sliding resistance, seizure, and galling is prevented. can do.

Therefore, the ring gear and the differential case are not locked by seizure or galling, and the function of separating the wheels during two-wheel drive is maintained. Therefore, running resistance does not occur, and a decrease in engine fuel efficiency is prevented. In addition, since the drive shaft is free from seizure and galling, the differential function of the differential mechanism and the turning and steering characteristics of the vehicle are maintained.

Further, since no seizure or galling occurs around the drive shaft in this way, unlike the conventional example,
The oil level does not need to be particularly high, and the amount of filled oil is minimal.

Therefore, even if the seal is broken, the oil does not leak to the outside, and can be advantageously obtained in the failure mode.

Further, since the amount of oil is reduced, the speed reduction mechanism and the differential gear are lighter and the cost can be reduced.

Also, drag torque (dragging torque) is reduced due to the fact that the rotational resistance between the ring gear and the differential case is small, that there is no sliding resistance around the drive shaft, and that the amount of oil used as stirring resistance is small. It becomes extremely small, suppressing the generation of running resistance due to drag torque, improving fuel economy, and improving the turning performance and turning performance of the vehicle.

According to a second aspect of the present invention, in the differential device according to the first aspect, the clutch device is provided on an outer periphery of a differential case, and the clutch device and the bearing are arranged in parallel in the axial direction. Thus, the same operation and effect as those of the first aspect can be obtained.

Since the clutch device is arranged on the outer periphery of the differential case, the outer case 203 (the boss 21
Unlike the conventional example in which the multi-plate clutch 207 is disposed between the outer periphery of 9) and the inner periphery of the inner case 205, the diameter of the clutch device can be increased, and the torque capacity of the clutch device is increased. It can transmit torque.

Further, in this configuration in which the clutch device and the bearing are arranged in parallel in the axial direction, the differential device is made compact in the radial direction, so that interference with peripheral members is prevented and the vehicle mountability is improved. Road clearance can be increased.

In addition, since a dimensional margin can be obtained in the radial direction by reducing the diameter, the diameter of the clutch device can be further increased by the margin and the torque capacity can be increased. When the diameter of the clutch device is increased, the load applied to the friction surface is reduced as the diameter is increased for the same capacity, and the durability is improved accordingly.

According to a third aspect of the present invention, there is provided the differential device according to the first or second aspect, wherein the clutch device is connected and disconnected by a main clutch disposed between a ring gear and a differential case by operating means. And a conversion means for, when the pilot clutch is connected, converting the transmission torque between the ring gear and the differential case into a pressing force while amplifying the transmission torque, and pressing and connecting the main clutch. As a feature, the same operation and effect as the configuration of claim 1 or 2 can be obtained.

When the pilot clutch is engaged, the converting means which operates by receiving the transmission torque between the ring gear and the differential case converts the transmission torque into a pressing force while amplifying the transmission torque, and presses the main clutch by the pressing force. To conclude.

At this time, when the slippage of the pilot clutch is adjusted by the operation means, the transmission torque applied to the conversion means (for example, a cam mechanism) changes, and the pressing force (cam thrust force) of the main clutch changes, and is transmitted to the differential case. The driving force of the engine can be controlled.

When the connection of the pilot clutch is released,
The pressing force of the conversion means (thrust force of the cam mechanism) disappears, the connection of the main clutch is released, and the wheels from the differential case are disconnected.

In this configuration, since the pressing force of the main clutch is amplified by the conversion means, a sufficient clutch capacity can be obtained even if a small and lightweight main clutch is used.
Sufficient driving force can be transmitted to the wheels.

Further, the differential device configured to press the main clutch with the pressing force amplified by the conversion means is more compact than a configuration having a clutch device having the same capacity without an amplification function. The on-board performance is improved.

[0046]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A rear differential 1 (differential device for distributing driving force to left and right rear wheels) mounted on a four-wheel drive vehicle according to an embodiment of the present invention will be described with reference to FIG.

The rear differential 1 has the features of claims 1 to 3. The left and right directions are the vehicle using the rear differential 1 and the left and right directions in FIG. 1, and members without reference numerals and the like are not shown.

The rear differential 1 is arranged on the rear wheel side where the driving force is cut off during the two-wheel drive traveling of the four-wheel drive vehicle.

In particular, the vehicle of this embodiment is a four-wheel drive vehicle in which the front wheels are driven by an engine and the rear wheels are driven by an electric motor using auxiliary power.

This vehicle has a front wheel power system including an engine, a transmission, a front differential (a differential device for distributing the driving force of the engine to the left and right front wheels), a front wheel drive shaft, left and right front wheels, and the like.
A rear wheel side power including an electric motor, a controller for the electric motor, a controller for controlling the electric motor based on information from the sensor, a speed reduction mechanism 3, a rear differential 1, a rear wheel drive shaft, left and right rear wheels, and the like. During normal driving, the front wheels are driven by the engine, and the rear wheels are driven by the electric motor when necessary, for example, when starting, accelerating, or when the front wheels idle. It is driven auxiliary.

FIG. 1 shows the rear differential 1 and a part of the speed reduction mechanism 3.

The rear differential 1 comprises a ring gear 5, a differential case 7, ball bearings 9, 9 (bearings), a bevel gear type differential mechanism 11, a clutch device 13, and the like.

The rear differential 1 and the speed reduction mechanism 3 are housed in a casing. The casing is constituted by a differential carrier 15 having a gear casing for housing the speed reduction mechanism 3 and a differential carrier for housing the rear differential 1. The casing is filled with oil, and an oil reservoir is provided inside the casing.

The reduction mechanism 3 is composed of a three-stage reduction gear set arranged outside the figure, and each reduction gear set is composed of a small-diameter input-side reduction gear and a large-diameter output-side reduction gear.

The input side reduction gear of the first stage reduction gear set is the first reduction gear.
The output side reduction gear is formed on the shaft, and is fixed to the second shaft.

The input side reduction gear of the second stage reduction gear set is formed on the second shaft, and the output side reduction gear 17 is fixed to the third shaft 19.

The input-side reduction gear 21 of the third-stage reduction gear set
Is formed on the third shaft 19. The output side reduction gear is the ring gear 5, which is fixed to the clutch housing 23 by welding or the like.

The third shaft 19 has a ball bearing 25 at the left end.
As a result, the right end is supported by the differential carrier portion 15 by a roller bearing 27. An opening 29 is provided in the differential carrier section 15 on the left end side of the third shaft 19, and a cover 30 is attached to the opening 29 to prevent foreign matter from entering and oil leakage.

The first shaft, the second shaft, and the third shaft 17 are arranged in parallel with each other, and each transmission gear set is constituted by a spur gear in this embodiment.

The first shaft is connected to the output shaft of an electric motor, which is an auxiliary driving force for driving the rear wheels, and the reduction mechanism 3 reduces the rotation of the electric motor to three stages, amplifies the torque, and amplifies the torque. To rotate.

The ring gear 5 is supported on a differential case 7 by ball bearings 9,9.

The ring gear 5 and the ball bearings 9 and 9 are provided on the same axis, and in the present embodiment, are almost completely wrapped in the axial direction. The differential case 7 is also on the same axis and in the axial direction. Is wrapped around.

The differential mechanism 11 between the left and right wheels includes a pinion shaft 31, a pinion gear 33, left and right side gears 35,
37.

A plurality of pinion shafts 31 are arranged radially from the center of the differential case 7, and the tip of each pinion shaft 31 is connected to the differential case 7 and is prevented from falling off by a spring pin 39.

The pinion gear 33 is a pinion shaft 31
The differential case 7 and the pinion gear 33
A spherical washer 41 that receives the centrifugal force of the pinion gear 33 and the reaction force of meshing with the side gears 35 and 37 is disposed between them.

The side gears 35 and 37 are in mesh with the pinion gear 33, respectively. Between the side gears 35 and 37 and the differential case 7, there is disposed a thrust washer 43 for receiving the meshing reaction force of the side gears 35 and 37.

The side gears 35 and 37 are spline-connected to the left and right drive shafts, respectively. Each drive shaft penetrates the outside from the differential carrier portion 15 and is connected to the left and right rear wheels via a joint.

Further, oil seals 45 for preventing oil from leaking to the outside are arranged between the drive shafts and the couplings and the differential carrier portion 15.

The driving force of the electric motor for rotating the ring gear 5 is transmitted to the differential case 7 by the clutch device 13 as described later. The rotation of the differential case 7 is distributed from the pinion shaft 31 to each of the side gears 35 and 37 via the pinion gear 33, and further transmitted from the drive shaft to the left and right rear wheels, and the vehicle enters a four-wheel drive state.
The ability to escape on rough roads, to drive, to start, to accelerate, and to stabilize the vehicle body is greatly improved.

When a difference in driving resistance occurs between the left and right wheels on a bad road or the like, the driving force of the electric motor is differentially distributed to the left and right rear wheels by the rotation of the pinion gear 33.

The clutch device 13 comprises an electromagnet 47 (operating means), a multi-plate type main clutch 49 and a pilot clutch 51, a ball cam 53 (converting means), a return spring 55, a controller and the like.

The core 57 of the electromagnet 47 is the differential carrier 1
5, and its lead wire is drawn out and connected to a vehicle-mounted battery and a controller.

The left end of the differential case 7 is supported by the differential carrier 15 by a ball bearing 59, and the right end is supported by a core 57 (the differential carrier 15) by the ball bearing 59.

A rotor 61 made of a magnetic material as a side wall member is spline-connected to the right end side of the differential case 7, and is positioned rightward by a snap ring 63.

The main clutch 49 is located on the right side of the ball bearings 9, 9, in the clutch housing 3 and the differential case 7.
, And the pilot clutch 51 is disposed between the clutch housing 23 and the cam ring 65.

The ball cam 53 is disposed between the cam ring 65 and the pressure plate 67. The pressure plate 67 is spline-connected to the differential case 7, and presses the main clutch 49 by receiving the cam thrust force of the ball cam 53 as described below.

[0077] Between the rotor 61 and the cam ring 65,
A thrust bearing 69 receiving a cam reaction force of the ball cam 53 is arranged.

The return spring 55 is disposed between the pressure plate 67 and the differential case 7, and urges the pressure plate 67 in a direction opposite to the pressing force of the main clutch 49.

The rotor 61 constitutes a part of a magnetic circuit of the electromagnet 47, and an air gap having a predetermined width which becomes a part of the magnetic circuit is provided between the rotor 61 and the core 57. Further, the rotor 61 is magnetically separated by a stainless steel (non-magnetic) ring 71 on the outside and inside in the radial direction, thereby preventing a short circuit of magnetic force.

An armature 73 is arranged between the pressure plate 67 and the pilot clutch 51 so as to be movable in the axial direction, and is positioned by a snap ring so as not to contact the pressure plate 15.

As shown in FIG. 1, the electromagnet 47, the main clutch 49, the pilot clutch 51, the ball cam 53 and the return spring 55 constituting the clutch device 13 are arranged coaxially with the differential case 7, and the main clutch 49 and the ball The bearings 9 and 9 are arranged axially with respect to each other.

The controller excites the electromagnet 47, controls the excitation current, and stops the excitation. Further, the controller rotates the rear wheel driving electric motors in conjunction with the excitation and the excitation stop to stop the rotation.

As described above, when the electric motor is rotated, the electromagnet 47 is excited, and when the electromagnet 47 is excited,
The armature 73 is sucked and presses the pilot clutch 51 to fasten it.

When the pilot clutch 51 is engaged,
Clutch housing 2 by pilot clutch 51
3 (ring gear 5 side), a cam ring 65 connected to
The driving force of the electric motor is applied to the ball cam 53 via the pressure plate 67 on the differential case 7 side. The ball cam 53 amplifies this driving force and converts it into a cam thrust force, and presses the main clutch 49 via the pressure plate 67. , To be concluded.

When the clutch device 13 is connected in this manner, the rotation of the ring gear 5 is controlled by the differential case 7 as described above.
The rotation is distributed to the left and right rear wheels by the differential mechanism 11, and the vehicle enters a four-wheel drive state.

At this time, when the exciting current of the electromagnet 47 is controlled, the slip of the pilot clutch 51 changes, the cam thrust force of the ball cam 53 changes, and the driving force transmitted to the rear wheels is controlled.

When such driving force control is performed, for example, during turning, the turning performance and the stability of the vehicle body can be greatly improved.

When the excitation of the electromagnet 47 is stopped, the pilot clutch 51 is released, the cam thrust force of the ball cam 53 disappears, the pressure plate 67 returns to the right by the urging force of the return spring 55, and the main clutch 49 is released. Then, the connection of the clutch device 13 is released, and the vehicle is brought into a two-wheel drive state by the front wheel drive of the engine.

At this time, the controller, as described above,
Stop the rotation of the electric motor.

When the controller starts the vehicle, the controller rotates the electric motor and sets the clutch device 1
3 is connected to form a four-wheel drive state, the driving force of the vehicle is enhanced by the driving force of the engine and the electric motor, and the startability and acceleration are improved.

When the vehicle speed is a predetermined value (for example, 20 km /
When h) is reached and the driving force of the electric motor becomes unnecessary, the controller stops the rotation of the electric motor, and in conjunction with this, releases the connection of the clutch device 13 to bring the vehicle into the two-wheel drive state.

[0092] Further, the controller can put the vehicle in the above-described four-wheel drive state even when climbing a hill, and can enhance the driving force of the vehicle.

If a rollback phenomenon occurs in which the front wheels idle and the vehicle moves backward during the climb, the controller stops the rotation of the electric motor and releases the connection of the clutch device 13.

When the connection of the clutch device 13 is released,
The rear wheel is brought into the entrained state, and the electric motor is separated from the rear wheel, and is released from being forcedly rotated by the rotation of the rear wheel (forward rotation during forward running, reverse rotation during rollback).

Further, when it is desired to increase the driving torque during traveling irrespective of the predetermined vehicle speed after the start,
If the clutch device 13 is connected by rotating the electric motor, it is possible to further improve the ability to ride over a step or a depression and the acceleration of the vehicle.

Helical oil grooves 79, 81 are provided on the inner periphery of the boss portions 75, 77 of the differential case 7 through which the left and right drive shafts respectively penetrate. The differential case 7 has an arrow 8 at a portion corresponding to the main clutch 49.
The clutch housing 2 is provided with an opening indicated by 3.
3 is provided with an opening 85 at a portion corresponding to the pilot clutch 51.

The oil in the oil sump flows into the inside from the oil grooves 79 and 81 with the rotation of the differential case 7 to lubricate and cool the meshing portions of the gears of the differential mechanism 11 and the spherical washer 41, and further centrifugal force. As a result, it flows out from the opening of the arrow 83 to the main clutch 49 side, and
9, the ball bearings 9, 9, the ball cam 53, the pilot clutch 51, the thrust bearing 69, etc. are lubricated and cooled, and flow out of the opening 85 to return to the oil reservoir.

The ball bearings 9, 9 are also lubricated and cooled by the oil splashed by the rotation of the ring gear 5.

The coil 87 of the electromagnet 47 is cooled by oil to stabilize its characteristics, and the heat of the coil 87 heats the oil in the oil pool and the surrounding pilot clutch 51 and ball cam 53 to warm the oil. Circulates to warm each of the above components.

Thus, the rear differential 1 is configured.

The rear differential 1 has the ring gear 5 in the two-wheel drive state in which the coupling of the clutch device 13 is released by disposing the ball bearings 9, 9 between the ring gear 5 and the differential case 7 as described above. And the differential case 7 do not slide directly, so that the rotational resistance is extremely small.

Further, in this embodiment, the clutch device 13 is disposed between the inner periphery of the ring gear 5 and the outer periphery of the differential case 7, and the left and right drive shafts are supported only on the differential case 7 side. Unlike
There is no need to support the left and right drive shafts on the side of the ring gear 5, and there is no sliding between them in the two-wheel drive state.

Further, since the ring gear 5, the ball bearings 9, 9 and the differential case 7 are wrapped in the axial direction, the meshing reaction force of the ring gear 5 can be supported by the ball bearings 9, 9. Seizure and galling between the case 5 and the differential case 7 can be prevented.

As described above, the ring gear 5 and the differential case 7
In addition, in the two-wheel drive state, no sliding occurs at the support portion of the drive shaft, and seizure and galling can be prevented.

Accordingly, the ring gear 5 and the differential case 7 are not locked by seizure or galling, and the function of separating the rear wheels during two-wheel drive is maintained. As a result, it is possible to prevent a reduction in fuel consumption and to prevent seizure and galling around the drive shaft.
The differential function of the differential mechanism 11 and the turning performance and steering performance of the vehicle can be improved.

Further, since no seizure or galling occurs around the drive shaft in this way, unlike the conventional example,
It is not necessary to particularly increase the oil level of the casing (differential carrier section 15), and the amount of oil to be filled is minimized.

Therefore, even if the oil seal 45 is broken, the oil does not leak to the outside, and the failure mode can be obtained more advantageously.

Further, by reducing the amount of oil,
The speed reduction mechanism 3 and the rear differential 1 become lighter and lower in cost.

Further, the rotational resistance between the ring gear 5 and the differential case 7 is small, there is no sliding resistance around the drive shaft, and the amount of oil that becomes the rotational resistance (stirring resistance) of each rotating member is small. As a result, the drag torque becomes extremely small, so that the fuel efficiency is further improved and the turning performance of the vehicle due to the drag torque,
Turning performance can be improved.

In the case of a four-wheel drive vehicle using an electric motor as the auxiliary driving force as in the present embodiment, as described above, there is no lock due to image sticking or galling, so
When a rollback phenomenon occurs at the time of wheel drive traveling or at the time of climbing a slope, the electric motor can be reliably separated from the rear wheel by the clutch device 13, and the electromotive force of the electric motor causes the battery, the alternator, and the control circuit to operate. A large load is prevented from being applied to the constituent elements and the like.

Accordingly, these functions are maintained normally, and the durability is greatly improved.

Further, since the lock does not occur, the electric motor is not forcibly rotated by the rotation of the rear wheel, and the load on the winding on the magnetic field side or the rotor side, the temperature rise, the load on the bearing, and the like are reduced. As a result, the durability of the electric motor is greatly improved.

Further, in the brush-type electric motor, the durability of the brush is improved, so that the number of times of replacement of the brush can be reduced accordingly, and the maintenance cost can be greatly reduced.

Further, since the electric motor is not mechanically turned by the drag torque, the protection function of the battery, the alternator, the circuit elements, etc., and the durability of the electric motor are further improved.

Further, in the present embodiment, since the rear differential 1 has the clutch device 13 arranged on the outer periphery of the differential case 7, the rear differential 1 has a multi-plate structure between the outer periphery of the outer case 203 (boss portion 219) and the inner periphery of the inner case 205. Unlike the conventional example in which the clutch 207 is arranged, the diameter of the clutch device 13 can be increased, the torque capacity of the clutch device 13 can be increased, and a large torque can be transmitted.

Since the ball bearings 9 and 9 and the clutch device 13 are arranged in parallel in the axial direction, the diameter is reduced, so that interference with the differential carrier 15 and the third shaft 19 of the speed reduction mechanism 3 is prevented. As a result, the vehicle-mounted performance is improved, and the road clearance of the vehicle body can be increased.

Further, due to the dimensional allowance obtained by reducing the diameter, the diameter of the clutch device 13 can be further increased, and the torque capacity can be increased.

If the diameter of the clutch device 13 is increased,
With the same capacity, the load on the friction surface is reduced as the torque is increased, so that the durability is improved accordingly.

Further, since the pressing force of the main clutch 49 is amplified by the ball cam 53, the main clutch 4
Even if 9 is small and lightweight, a sufficient clutch capacity can be obtained, and a sufficient driving force can be transmitted to the rear wheels.

Further, since the ball cam 53 for amplifying the pressing force of the main clutch 49 is provided as described above, the clutch device can be reduced in size as compared with a configuration having a clutch device of the same capacity without an amplifying function. Can be made more compact, and the on-board performance can be improved.

Further, since the oil and the main clutch 49 are heated by the heat of the electromagnet 47 (coil 87), especially when the clutch device 13 is disconnected,
When the temperature of the oil is low, the drag torque on the rear wheel side generated by the viscosity of the oil is reduced, the loss of the engine driving force is reduced, and the fuel efficiency is improved.

Further, by using the multi-plate type main clutch 49 and the pilot clutch 51 for the clutch device 13, the ratchet noise unlike the meshing clutch is not generated, so that the quietness is high, and at the time of connection and disconnection. Freed from shock and shock noise.

Further, the clutch device 13 using the multi-plate type main clutch 49 and the pilot clutch 51 does not need to synchronize the rotation at the time of connection and disconnection, so that
Since no synchronization mechanism is required, the rear differential 1 can be configured to be lighter, more compact, and lower in cost.

In the above-described embodiment, an example is shown in which the present invention is applied to a differential device of a four-wheel drive vehicle in which the engine is used as the main driving force source and the electric motor is used as the auxiliary driving force source. Instead, the differential device of the present invention can be used on the drive wheel side that is cut off during the two-wheel drive of a four-wheel drive vehicle using the engine as a driving force source.

In this case, it is needless to say that the same effect can be obtained except for the effect relating to the electric motor.

In the present invention, the ring gear 5, the differential case 7, and the bearing 9 are arranged almost completely wrapped in the axial direction. However, they are arranged such that a part thereof is wrapped in the axial direction. It goes without saying that the same operation and effect can be obtained even if they are arranged.

Further, the bearing 9 disposed between the ring gear 5 and the differential case 7 is an example using a rolling bearing such as a ball bearing. However, the present invention is not limited to this.
A sliding bearing may be used.

The operating means of the pilot clutch is as follows:
Not limited to the electromagnet, a fluid pressure actuator such as a hydraulic actuator, an electric motor, or the like may be used.

The main clutch and the pilot clutch according to the third aspect of the invention may use any type of clutch other than the multi-plate clutch as long as it is a friction clutch such as a single-plate clutch or a cone clutch. These may be wet or dry.

Further, the clutch plates of the multi-plate clutch and the single-plate clutch are not particularly specified in the embodiments, but any one of steel, carbon, paper and the like may be used as the clutch plate.

Further, the differential mechanism is not limited to a bevel gear type differential mechanism. For example, a planetary gear type differential mechanism,
Any of a differential mechanism in which an output side gear is connected to a pinion gear slidably accommodated in an accommodation hole of a differential case, a differential mechanism using a worm gear, or the like may be used.

Further, the differential device of the present invention
It goes without saying that the present invention can also be used for a front differential when the front wheels are separated from the driving force during two-wheel drive of a four-wheel drive vehicle.

[0133]

According to the differential device of the first aspect, the ring gear and the differential case do not slide directly, and do not slide around the drive shaft in a two-wheel drive state in which the coupling of the clutch device is released. Therefore, it is possible to suppress the occurrence of image sticking and galling at these locations.

Since the meshing reaction force of the ring gear can be supported by the bearing that supports the ring gear on the differential case, no sliding resistance is generated between the ring gear and the differential case, and seizure and galling are prevented. be able to.

In addition, since the ring gear and the differential case are not locked as described above, the function of separating the wheels is maintained, and there is no running resistance due to the separated side. Since no seizure or galling occurs on the shaft, the differential function of the differential mechanism and the turning and steering characteristics of the vehicle are maintained.

In addition, the amount of oil to be filled is minimized, and even if the seal is broken, the oil does not leak to the outside, and the failure mode is improved.

Further, the differential device and the speed reduction mechanism are reduced in weight as the amount of oil is reduced, so that the cost is reduced.

Further, since no sliding resistance is generated and the amount of oil that becomes stirring resistance is small, drag torque is extremely reduced, fuel efficiency is improved accordingly, and deterioration of turning performance and turning performance of the vehicle is prevented. Is done.

According to the differential device of the second aspect, the same effect as the configuration of the first aspect can be obtained.

Further, since the clutch device is arranged on the outer periphery of the differential case, the diameter of the clutch device can be increased, and the torque capacity of the clutch device can be increased to transmit a large torque.

Further, by arranging the clutch device and the bearing in parallel in the axial direction, the diameter can be reduced in the radial direction, and interference with peripheral members is prevented, so that the vehicle mountability is improved and the road clearance of the vehicle body is increased.

Further, the diameter of the clutch device can be increased due to the dimensional allowance due to the reduction in diameter in the radial direction, so that the torque capacity can be further increased. And the durability can be improved.

The differential device according to the third aspect can provide the same effect as the configuration according to the first or second aspect.

Further, the conversion means for amplifying the pressing force of the main clutch can provide a sufficient clutch capacity, and can be more compact and can be mounted on a vehicle as compared with a configuration having no amplifying function.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of one embodiment.

FIG. 2 is a sectional view of a conventional example.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 Rear differential (differential device) 3 Reduction mechanism 5 Ring gear 7 Differential case 9 Ball bearing (bearing) 11 Differential mechanism 13 Clutch device 21 Reduction gear of reduction mechanism 3 47 Electromagnet (operating means) 49 Main clutch 51 Pilot clutch 53 Ball cam (conversion) means)

Claims (3)

[Claims] 1. A differential device comprising a plurality of pairs of reduction gears, whose rotation axes are arranged parallel or orthogonal to each other, and provided with a reduction mechanism for reducing the rotation of a driving force source, A ring gear meshing with the reduction gear of the mechanism, a differential case coaxially arranged with the ring gear, a clutch device for intermittently connecting between the ring gear and the differential case, and a rotation of a driving force source input to the differential case via the clutch device on a wheel side. And a differential mechanism for distributing the gears to the ring gear and the differential case, and the bearings that support each other are arranged between the ring gear and the differential case.
A differential device characterized by being arranged so as to be wrapped in the axial direction. 2. The differential device according to claim 1, wherein the clutch device is provided on an outer periphery of the differential case, and the clutch device and the bearing are arranged in parallel with each other in the axial direction. 3. The invention according to claim 1, wherein the clutch device includes a main clutch disposed between a ring gear and a differential case, a pilot clutch intermittently operated by operating means, When the pilot clutch is connected, the differential device includes a conversion means for converting the transmission torque between the ring gear and the differential case into a pressing force while amplifying the torque, and pressing and connecting the main clutch.