JP4715507B2 - Left / right driving force distribution device - Google Patents

Description

  The present invention relates to a left / right driving force distribution device suitable for adjusting driving force distribution (torque movement) to left and right wheels in an automobile.

2. Description of the Related Art Conventionally, there has been known a technique capable of changing a driving force distribution state of left and right wheels of a vehicle (see, for example, Patent Document 1). In such a technique, a driving force distribution mechanism is provided between the left and right driving wheels together with a differential gear, and the driving force distribution state is controlled by controlling the operation of the driving force distribution mechanism.
The driving force distribution mechanism includes an acceleration / deceleration mechanism that accelerates and decelerates one of the left and right wheels relative to the other wheel, a first clutch mechanism that transmits rotation on the acceleration side to the other wheel, and a deceleration side A second clutch mechanism for transmitting the rotation to the other wheel.

  However, in such a configuration, there are different control objects (clutch mechanisms) for the case of torque movement to the right wheel and the case of torque movement to the left wheel, which causes an increase in weight and cost. In particular, when a hydraulic clutch mechanism is applied as an object to be controlled, a hydraulic source for supplying hydraulic pressure, a hydraulic circuit, and the like are required, which further increases weight and costs. Further, since the clutch mechanism is used, there is a problem that torque loss occurs during torque movement.

On the other hand, for example, Patent Document 2 discloses a technique in which a motor is used instead of a clutch mechanism to distribute torque between left and right wheels. By using the motor in this way, only one motor can be controlled, and the control logic and the like can be simplified.
Japanese Patent No. 2738225 Japanese Patent No. 2687052

However, in the technique disclosed in Patent Document 2, although it is possible to control only one motor, there is a problem that the entire unit including the differential gear becomes large. In particular, the technique disclosed in Patent Document 2 has a problem of increasing the size in the radial direction of the drive shafts of the left and right wheels.
In an automobile with an engine mounted in the front of the vehicle and driving the rear wheels, the differential gear for the rear wheels is provided in a narrow space between the ground and the floor panel. When a force distribution mechanism is provided, there is almost no space in the radial direction. For this reason, in the technique disclosed in the cited document 2, it is difficult to provide the driving force distribution mechanism on the rear wheel side.

  The present invention has been devised in view of such problems, and in particular, it is possible to reduce the size and weight of the axle in the radial direction, and to easily mount it on various vehicles. The purpose is to provide.

  The left and right driving force distribution device of the present invention includes a first planetary gear mechanism, a second planetary gear mechanism, and an electric motor that are arranged in parallel and coaxially, and the first planetary gear mechanism is one of the left and right wheels. A first sun gear connected to the wheels, a first carrier fixed to a casing that houses the two sets of planetary gear mechanisms, a first carrier that is pivotally supported by the first carrier and meshes with the first sun gear. A planetary gear and a first ring gear meshing with the first planetary gear are provided, and the second planetary gear mechanism is connected to a second sun gear connected to the other wheel of the left and right wheels, and to a rotating shaft of the electric motor The second planetary gear, the second planetary gear pivotally supported by the second carrier and meshing with the second sun gear, and meshing with the second planetary gear and integrally formed with the first ring gear. Second ring It is characterized in that it comprises the A (claim 1).

In addition, it is preferable that a differential device is provided between the first sun gear and the second sun gear to receive a driving force from a driving source and absorb a difference in rotational speed between the left and right wheels ( Claim 2).
Preferably, a drive source is provided at the front of the vehicle, and the first and second sun gears are connected to the left and right wheels on the rear side of the vehicle.

The electric motor is preferably housed in the casing.
Further, the first sun gear and the second sun gear are formed with the same number of teeth and the same diameter, the first planetary gear and the second planetary gear are formed with the same number of teeth and the same diameter, and The first ring gear and the second ring gear are preferably formed to have the same number of teeth and the same diameter.

  According to the left and right driving force distribution device of the present invention, the entire device can be reduced in size. Particularly, since the first planetary gear mechanism, the second planetary gear mechanism, and the electric motor are arranged side by side on the same axis, it is possible to reduce the size of the device in the radial direction and to greatly improve the vehicle mountability. Accordingly, the driving force distribution device can be easily provided on the rear wheel side of a vehicle having a small space, particularly an automobile equipped with an engine at the front of the vehicle.

Hereinafter, the left and right driving force distribution device according to the first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing the configuration of the main part, and FIG. FIG. 3 and FIG. 3 are schematic views showing a modification of the first embodiment.
In FIG. 2, reference numeral 1 denotes a vehicle to which the present invention is applied, 2 is an engine, and 3 is a transmission. The driving force of the engine 2 is transmitted to a center differential (hereinafter referred to as center differential) 5 via a transmission 3, and the driving force is distributed and transmitted from the center differential 5 to the front wheels 8 and the rear wheels 14.

  That is, one of the driving forces input to the center differential 5 is output to the front differential (hereinafter referred to as front differential) 6 and transmitted to the front left and right wheels 8L and 8R via the drive shafts 7L and 7R. The other one is connected to the rear left and right wheels 14R, 14L via the hypoid gear mechanism 9, the propeller shaft 10, the hypoid gear mechanism 11, the rear differential (hereinafter referred to as rear differential) 12, and the drive shafts 13L, 13R. It is to be transmitted.

  Further, the center differential 5 of the vehicle 1 is provided with a front and rear wheel driving force distribution mechanism 19 that distributes the driving force by limiting the differential between the front wheels 8 and the rear wheels 14. In this embodiment, the front and rear wheel driving force distribution mechanism 19 is configured as a clutch mechanism provided adjacent to the front differential 6, and the front wheel 8 and the rear wheel 14 are changed by changing the degree of engagement of the clutch mechanism. And the torque output from the engine 2 can be variably distributed to the front and rear wheels 8 and 14.

  By the way, the rear differential (differential device) 12 is provided with a left and right wheel driving force distribution mechanism (driving force adjusting means) 15 that can adjust the driving force distribution transmitted to the left rear wheel 14L and the right rear wheel 14R. Yes. Hereinafter, the configuration of the rear differential 12 and the left and right wheel driving force distribution mechanism 15 will be described with reference to FIG. 1. The rear differential 12 is configured using a planetary gear mechanism so that driving torque is input to the ring gear 12a. It has become. In addition to the ring gear 12a, the planetary gear mechanism includes a planetary gear 12b that meshes with the inside of the ring gear 12a, and a planetary carrier that supports the planetary gear 12b so that the planetary gear 12b can rotate (spin) (hereinafter simply referred to as a carrier). 12c, and a sun gear 12d that meshes with the planetary gear 12b. The carrier 12c is connected to the left drive shaft 13L, and the rotation shaft of the sun gear 12d is connected to the right drive shaft 13R.

The ring gear 12a, the planetary gear 12b, the carrier 12c, and the sun gear 12d rotate together without rotating relative to each other when traveling straight, and the carrier 12c rotates relative to the sun gear 12d during turning to move left and right. The difference in rotational speed between the drive shafts 13L and 13R is absorbed.
The left and right wheel driving force distribution mechanism 15 includes two planetary gear mechanisms 16 and 17 and a motor (electric motor) 18 arranged in parallel. The planetary gear mechanisms 16 and 17 and the motor 18 are All are arranged coaxially with the rotation shaft of the rear differential 12 (that is, the rotation center shaft of the ring gear 12a, the planetary carrier 12c, and the sun gear 12d).

Of these, the sun gear (first sun gear) 16d of one planetary gear mechanism (first planetary gear mechanism) 16 disposed on the left wheel side is connected to the carrier 12c of the rear differential 12 via a hollow shaft 16d '. Thus, the sun gear 16d of the first planetary gear mechanism 16 and the carrier 12c of the rear differential 12 are integrated.
Further, a right drive shaft 13R connected to the sun gear 12d of the rear differential 12 is disposed coaxially with the sun gear 16d and the hollow shaft 16d ′ inside the hollow shaft 16d ′.

  A planetary gear (first planetary gear) 16b is disposed on the outer periphery of the sun gear 16d, and a ring gear 16a is disposed on the outer periphery of the planetary gear 16b. The planetary gear 16b is rotatably supported by a carrier (first carrier) 16c. The carrier 16c is fixed to a casing 4 that integrally houses the rear differential 12 and the left and right wheel driving force distribution mechanism 15. Therefore, the planetary gear 16b is allowed to rotate only with respect to the sun gear 16d, and revolving is restricted.

  As shown in FIG. 1, the other planetary gear mechanism (second planetary gear mechanism) 17 disposed on the right wheel side shares the ring gear with the first planetary gear mechanism 16. That is, the ring gear (second ring gear) 17a of the second planetary gear mechanism 17 and the ring gear 16a of the first planetary gear mechanism are integrally formed, and these two ring gears 16a and 17a have the same diameter and It is formed as the same number of teeth. The ring gear 17 is supported rotatably with respect to the casing 4 via a bearing (not shown).

  The ring gear 17a meshes with a planetary gear (second planetary gear) 17b rotatably supported by a carrier (second carrier) 17c. The carrier 17c is a rotor (rotor) of the motor 18. It is formed integrally with a hollow shaft (motor rotation shaft) 18c connected to 18b. A right drive shaft 13R is coaxially arranged inside the hollow shaft 18c.

  The planetary gear 17b is engaged with a sun gear (second sun gear) 17d. Here, the sun gear 17d is disposed coaxially with the right drive shaft 13R and is integrated with the drive shaft 13R. Therefore, when the right wheel 14R rotates, the sun gear 12d of the rear differential 12 and the sun gear 17d of the second planetary gear mechanism 17 always rotate.

Further, in the first planetary gear mechanism 16 and the second planetary gear mechanism 17, the sun gears 16d and 17d are also set to have the same diameter and the same number of teeth, and the planetary gears 16b and 17b have the same diameter and the same number of teeth. Is set.
Further, the motor 18 is disposed in the axle direction (in the vehicle width direction) of the two planetary gear mechanisms 16 and 17, and in the present embodiment, a stator (stator) 18a is disposed on the outer peripheral side, and the stator A rotor (rotor) 18b is disposed inside 18a. The rotor 18b may be disposed on the outer peripheral side and the stator 18a may be disposed on the inner side.

Then, by controlling the operation of the motor 18 in accordance with the traveling state of the vehicle and the like, the state of driving force distribution (torque distribution) is appropriately changed between the left and right wheels 14L and 14R, and the driving torque of one wheel is increased. Or it can be reduced.
As shown in FIG. 2, the vehicle 1 is provided with driving force distribution control means (ECU) 20 for controlling the operating states of the left and right wheel driving force distribution mechanism 15 and the front and rear wheel driving force distribution mechanism 19. The ECU 20 is provided with a CPU, a ROM, a RAM, an interface, etc., all not shown. The ECU 20 includes a vehicle speed sensor that detects the traveling speed of the vehicle 1, a yaw rate sensor that detects the yaw rate (yaw momentum) of the vehicle, a handle angle sensor that detects the handle angle (steering angle) of the vehicle, and the left and right sides of the rear wheels 14. A wheel speed sensor (not shown) for detecting the wheel speed of each wheel is connected. In addition to these sensors, various sensors such as an engine speed sensor, a front / rear G sensor, a lateral G sensor, and a throttle position sensor are connected.

Based on the information detected by these various sensors, the ECU 20 sets control signals for the left and right wheel driving force distribution mechanism 15, particularly the motor 18, according to the traveling state of the vehicle.
For example, the ECU 20 calculates a target value (target wheel speed difference) of the left and right wheel speeds according to the traveling state of the vehicle 1 based on the vehicle speed and the steering wheel angle, and also calculates the actual left and right wheel speed difference (actual wheel speed difference). ) Is set and output so that the control signal for the motor 18 is set to be the target wheel speed difference.

Since the left / right driving force distribution device according to the first embodiment of the present invention is configured as described above, the following operations and effects are achieved.
When the vehicle travels straight, the motor 18 does not rotate but remains stationary, and when the vehicle turns, the motor 18 rotates according to the difference in rotational speed between the left and right wheels. That is, when the vehicle travels straight, the rotational speeds of the left and right drive shafts 13L, 13R match, so the rotational speeds of the sun gears 16d, 17d of the first and second planetary gear mechanisms 16, 17 match. Therefore, the planetary gears 16b and 17b also rotate at the same speed, and the ring gear 17a rotates with the carrier 17c and the motor rotating shaft 18c stationary.

  Further, by locking the motor 18, the drive shafts 13L and 13R are directly connected, and function as a limited slip differential (LSD). That is, by restricting the rotation of the rotor 18b, the motor 18 is locked (fixed), thereby restricting the rotation of the carrier 17c of the second planetary gear mechanism 17. In this case, the two sun gears 16d and 17d are only allowed to rotate at a constant speed, and are directly connected to improve the traction performance. Further, by limiting the rotation of the motor 18, the differential limit state can be changed linearly.

  On the other hand, when turning, the rear differential 12 absorbs the difference in rotational speed between the left and right wheels. At this time, a rotational speed difference occurs between the two sun gears 16d and 17d in accordance with the rotational speed difference between the left and right wheels, and the carrier 17c and the motor rotating shaft 18c rotate by this difference. When turning left, the motor 18 rotates in the same rotational direction as that of the right drive shaft 13R. When turning right, the motor 18 rotates in the opposite direction to the right drive shaft 13R.

  During such a turn, for example, the torque can be moved to the outer ring side by controlling the operation of the motor 18 so that the sun gear (one of the sun gears 16d and 17d) on the turning outer ring side increases. Specifically, by increasing the rotation speed of the motor rotating shaft 18c, the sun gear on the outer ring side (that is, the drive shaft on the outer ring side) is increased regardless of the turning direction of the vehicle. For example, when turning leftward in FIG. 1, the speed of the motor 18 is increased to increase the speed of the right wheel side drive shaft 13R and the right wheel 14R as the outer wheel side, and torque from the left wheel 14L to the right wheel 14R is increased. Move. When the vehicle is turning rightward, the motor 18 is accelerated to increase the speed of the left wheel side drive shaft 13L and the left wheel 14L as outer wheels, and the torque moves from the right wheel 14R to the left wheel 14L.

And by increasing the rotation speed of the motor 18 in this way, a yaw moment that promotes turning is generated in the vehicle 1, understeer is reduced, and turning performance can be improved.
On the contrary, the torque can be moved to the inner ring side by controlling the operation of the motor 18 so that the sun gears 16d, 17d on the turning inner ring side increase in speed. In this case, by reducing the number of rotations of the motor 18, the sun gears 16d and 17d on the inner ring side are increased regardless of the turning direction of the vehicle. As a result, a yaw moment that suppresses turning is generated, oversteer is reduced, and turning stability can be improved.

When the motor 18 is stopped by decelerating the rotation speed of the motor 18, the above-described locked state is established, and the difference in the rotation speed between the inner ring and the outer ring is eliminated.
As described above in detail, according to the left / right driving force distribution device of the present invention, by controlling the operation of the motor 18 and moving the torque to the turning outer wheel, the turning acceleration moment is applied and the turning performance is improved. Can do. Further, by moving the torque to the inner turning wheel, a turning suppression moment can be applied to improve turning stability. Further, by locking the operation of the motor 18, it functions as an LSD, and stability and traction performance can be improved.

  Further, even if the motor 18 cannot be used, the function of the rear differential 12 is not impaired, so that fail safe can be achieved. The conventional driving force distribution device using the hydraulic clutch mechanism requires a fail-safe system in which the two clutches for the left and right wheels do not engage simultaneously when a failure occurs in the hydraulic system. Fail-safety can be ensured without providing such a system.

In addition, torque can be moved to both the left and right wheels by controlling only one control target (motor), and the size and weight can be greatly reduced compared to the one provided with the hydraulic clutch mechanism, and the cost can be reduced. be able to. Further, since torque is applied by the motor, no torque loss occurs during torque movement.
Further, by providing the motor 18 coaxially adjacent to the two planetary gear mechanisms 16 and 17, it is possible to further reduce the size, and particularly to reduce the size in the radial direction compared to the conventional technology. it can. When this apparatus is applied to the driving force distribution on the rear wheel side of the vehicle 1 on which the engine 1 is mounted in the front as in this embodiment, there is a relatively large space in the vehicle width direction (axle direction). Since there is almost no margin in the radial direction, it was difficult to mount with a device that is enlarged in the radial direction as in the prior art, but according to the present invention, it is possible to reduce the size in the radial direction. There is a unique advantage that the mountability is greatly improved.

Next, a modification of the first embodiment will be described with reference to FIG. 3. FIG. 3 is a diagram showing a configuration when the present invention is applied to the driven wheel side where the driving force is not transmitted. The differential gear is omitted from the form, and other configurations are the same as those in the above-described embodiment.
That is, in this modified example, no differential gear is interposed between the first sun gear 16d and the second sun gear 17d, the first sun gear 16d is directly connected to the axle 23L of the left rear wheel 14L, and the second sun gear. 17d is directly connected to the axle 23R of the right rear wheel 14R.

In this case, the driving force from the engine 1 is not input to the left and right wheels 14L and 14R, but by controlling the operation of the motor 18, the driving force (torque) input from the road surface to the left and right wheels 14L and 14R is changed to the left and right wheels. The driving force distribution state of the left and right wheels can be changed.
In this modification, the driving power distribution mechanism 15 is applied to the rear wheel side of a so-called FF vehicle in which a driving source (engine) is mounted on the front portion of the vehicle to drive the front wheels. The driving force distribution mechanism 15 is applied to the front wheel side of a so-called FR vehicle that drives a rear wheel by mounting a power source, or the front wheel side of a so-called RR vehicle that drives a rear wheel by mounting a drive source at the rear of the vehicle. Also good.

Even when the left and right driving force distribution mechanism 15 is provided on the driven wheel side as described above, the steering characteristic can be changed by controlling the operation of the motor 18. Also in this modified example, the right and left driving force distribution mechanism 15 can be reduced in size, particularly in the radial direction, so that it can be easily mounted on various vehicles.
Next, the left and right driving force distribution device according to the second embodiment of the present invention will be described. FIG. 4 is a schematic diagram showing the configuration of the main part, and the type of differential gear applied to the first embodiment. Is different. In addition, since it is comprised similarly to 1st Embodiment except this, the same code | symbol is attached | subjected about the overlapping member, and description is abbreviate | omitted as much as possible.

  As shown in the figure, in the second embodiment, a bevel gear type rear differential 22 is provided as a differential device. Here, the bevel gear type rear differential 22 is a mechanism widely known from the prior art, and is composed of left and right side gears 22a and 22b, differential pinions 22c and 22d, and an input gear 22e. The left and right side gears 22a and 22b face each other and are coaxial with the input gear 22e. Further, differential pinions 22c and 22d are provided between the two side gears 22a and 22b, and these differential pinions 22c and 22d are supported by the input gear 22e so as to be able to rotate.

The left drive shaft 13L is connected to the left side gear 22a, and the right drive shaft 13R is connected to the right side gear 22b.
Further, the hollow rotary shaft 16d 'connected to the sun gear 16d of the first planetary gear mechanism 16 is connected to the input gear 22e of the rear differential 22, whereby the sun gear 16d is connected to the left wheel 14L via the rear differential 22. .

  And by comprising in this way, the effect similar to 1st Embodiment can be acquired. That is, by increasing the rotation of the motor 18, the torque can be moved to the turning outer wheel, and a turning acceleration moment can be applied. Therefore, in this case, the turning performance can be improved. Moreover, torque can be moved to the turning inner wheel by decelerating the rotation of the motor 18, and a turning restraining moment can be applied. Therefore, in this case, the turning stability can be improved. Furthermore, by locking the operation of the motor 18, traction can be improved.

Further, even in the case of such a configuration, it is possible to reduce the size in the radial direction as compared with the conventional technique, and the mounting property to the vehicle is improved.
Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, in FIGS. 1 and 3, the motor 18 is provided between the planetary gear mechanism 16 and the rear differential 12, 22, the carrier 16 c of the planetary gear mechanism 16 is connected to the motor rotation shaft 18 c, and the other planetary gear mechanism 17 is connected. The carrier 17c may be fixed to the casing 4. In this case, the planetary gear mechanism 16 serves as the second planetary gear mechanism described in the claims, and the planetary gear mechanism 17 includes the first planetary gear mechanism described in the claims. Become.

It is a schematic diagram which shows the principal part structure of the left-right driving force distribution apparatus which concerns on 1st Embodiment of this invention. 1 is a schematic diagram illustrating a configuration of a vehicle to which a left / right driving force distribution device according to a first embodiment of the present invention is applied. It is a schematic diagram shown about the modification of the left-right driving force distribution apparatus which concerns on 1st Embodiment of this invention. It is a schematic diagram which shows the principal part structure of the left-right driving force distribution apparatus which concerns on 2nd Embodiment of this invention.

Explanation of symbols

1 vehicle 2 engine (drive source)
3 Transmission 4 Casing 5 Center differential (center differential)
6 Front differential (front differential)
7L, 7R Drive shaft 8 Front wheel 9 Bevel gear mechanism 10 Propeller shaft 11 Bevel gear mechanism 12, 22 Rear differential (differential device)
13L, 13R Drive shaft 14 Rear wheel 15 Left and right wheel driving force distribution mechanism (driving force adjusting means)
16 first planetary gear mechanism 16a first ring gear 16b first planetary gear 16c first carrier 16d first sun gear 17 second planetary gear mechanism 17a second ring gear 17b second planetary gear 17c second carrier 17d second sun gear 18 motor (Electric motor)
18a Stator (stator)
18b Rotor (rotor)
18c Hollow shaft (motor rotation shaft)
19 Front and rear wheel driving force distribution mechanism 20 Driving force distribution control means (ECU)

Claims (5)

A first planetary gear mechanism, a second planetary gear mechanism, and an electric motor, which are arranged in parallel and coaxially, respectively;
The first planetary gear mechanism is
A first sun gear connected to one of the left and right wheels;
A first carrier fixed to a casing that houses the two sets of planetary gear mechanisms;
A first planetary gear supported by the first carrier and meshing with the first sun gear;
A first ring gear meshing with the first planetary gear;
The second planetary gear mechanism is
A second sun gear connected to the other wheel of the left and right wheels;
A second carrier connected to the rotating shaft of the electric motor;
A second planetary gear pivotally supported by the second carrier and meshing with the second sun gear;
A left and right driving force distribution device that meshes with the second planetary gear and includes a second ring gear configured integrally with the first ring gear. A differential device is provided between the first sun gear and the second sun gear to receive a driving force from a driving source and absorb a difference in rotational speed between the left and right wheels. The left / right driving force distribution device according to claim 1. The left and right driving force according to claim 1 or 2, wherein a driving source is provided at a front portion of the vehicle, and the first and second sun gears are connected to left and right wheels on the rear side of the vehicle. Distribution device. The left / right driving force distribution device according to claim 1, wherein the electric motor is housed in the casing. The first sun gear and the second sun gear are formed with the same number of teeth and the same diameter,
The first planetary gear and the second planetary gear are formed with the same number of teeth and the same diameter,
The left and right driving force distribution device according to any one of claims 1 to 4, wherein the first ring gear and the second ring gear are formed to have the same number of teeth and the same diameter.

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