JP2894399B2 - Vehicle with rear-wheel steering system linked to driving force distribution - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle with a driving force distribution interlocking type rear wheel steering device having a rear wheel left / right driving force distribution device and a rear wheel steering device.

[0002]

2. Description of the Related Art Conventionally, an automobile is steered by steering a front wheel. In recent years, in order to improve turning performance of a vehicle, a rear wheel is steered in addition to a front wheel. A four-wheel steering system has also been developed. In this four-wheel steering device, the rear wheel steering angle is adjusted in accordance with the steering angle (that is, the front wheel steering angle). Perform reverse phase steering,
At high speeds, in-phase steering is performed in which the rear wheels are turned to the same phase as the front wheels, with emphasis placed on the stability of the attitude of the vehicle when turning.

On the other hand, a means has been proposed in which a turning moment is generated in a vehicle by making the driving forces of left and right driving wheels non-uniform rather than turning the wheels, and the turning performance is improved by the turning moment. .

[0004]

In order to improve the turning performance of the vehicle, it is conceivable to use the rear wheel steering and the uneven distribution of the right and left driving forces in combination. The problem is how to control the driving force control. SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and has a driving force distribution interlocking rear wheel steering device capable of greatly improving the turning performance of a vehicle by using rear wheel steering together with driving force control. It is an object to provide a vehicle device.

[0005]

SUMMARY OF THE INVENTION Therefore, a vehicle with a driving force distribution interlocking type rear wheel steering device according to the present invention is provided with a driving force distribution device for distributing and adjusting the driving force from an engine to left and right wheels , and a vehicle.
In a vehicle provided with a rear wheel steering device for steering rear wheels by a predetermined steering amount corresponding to the steering amount of the vehicle, the driving force distribution device
Position is one of the left wheel side rotation shaft and the right wheel side rotation shaft.
The rotation speed is changed and the left wheel side rotation shaft and the right wheel side rotation shaft are changed.
Driving force transmitting means for transmitting driving force to one of the other
And the amount of driving force transmitted by the driving force transmitting means.
Driving force transmission amount control means, the rear wheel steering device
Corresponds to the driving force transmission amount of the driving force distribution device.
Rear wheel steering amount control means for controlling the steering amount of the rear wheel steering device;
It is characterized in that it is configured accordingly .

[0006] Preferably, the rear wheel steering device includes:
Turn the rear wheels at a specified front-rear steering angle ratio with respect to the steering amount of the vehicle.
The main steering mechanism to be steered, and additionally to the main steering mechanism
With the auxiliary steering mechanism capable of steering correction, the above-mentioned driving force transmission
The device and the auxiliary steering mechanism are controlled by a common hydraulic pressure
The configuration is as follows.

[0007]

In the vehicle with the driving force distribution interlocking type rear wheel steering device according to the first aspect of the present invention, the driving force distribution device has a structure.
The driving force transmission means that forms the left wheel side rotation shaft and the right wheel side rotation
The rotation speed of either of the rotation shaft and the
The driving force is applied to one of the side rotation shaft and the right wheel side rotation shaft.
Is transmitted. In addition, the driving force of the power transmission
The transmission amount is controlled by the driving force transmission amount control means. Ma
In addition, the rear wheel steering device controls the vehicle
The rear wheels are steered by the amount of steering.

[0008] After being provided in the rear wheel steering device,
The driving force transmission of the driving force distribution device is performed by the wheel steering amount control means.
The steering amount of the rear wheel steering device is controlled according to the amount. In the vehicle with a driving force distribution interlocking rear wheel steering device according to the present invention, both the driving force distribution device and the auxiliary steering mechanism are driven by hydraulic pressure, and the driving force distribution device And the auxiliary steering mechanism are controlled by the same hydraulic pressure.

[0009]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of a vehicle equipped with a driving force distribution interlocking type rear wheel steering device according to an embodiment of the present invention; FIG. FIG. 3 is a schematic diagram showing a configuration of a main part of the distribution-linked rear wheel steering device, FIG. 3 is a flowchart showing an operation of the main part, FIG.
7 are graphs showing control characteristics of the apparatus.

The vehicle with the driving force distribution interlocking type rear wheel steering device is provided with a driving force distribution device 60 and a rear wheel steering device 20. First, the driving force transmission system 1 in this vehicle
As shown in FIG. 1, the driving force transmission system 1 receives a driving force from an engine 2 via a transmission or the like by a center differential 3 formed of planetary gears, and transmits the driving force from the center differential 3 to the front wheel side. It transmits to the rear wheel side.

In particular, the center differential 3 is provided with a center differential limiting mechanism 24 that can appropriately limit the differential between the front and rear wheels. Here, the differential limiting mechanism 24 is constituted by a hydraulic multi-plate clutch, and is capable of controlling the distribution of driving force to the front and rear wheels while limiting the differential between the front and rear wheels according to the supplied oil pressure. , Which controls the distribution of driving force between the front and rear wheels.

In this way, one of the driving forces distributed from the center differential 3 is transmitted from the drive shafts 12 and 13 to the left and right front wheels 4 and 5 through the front differential 10. On the other hand, the other of the driving force distributed from the center differential 3 is transmitted to the rear differential 11 via the propeller shaft 62, and through the rear differential 11, the left and right rear wheels 6, 7
It is transmitted to.

The rear differential 11 is provided with a driving force transmitting means including a transmission mechanism 26 and a multi-plate clutch mechanism 27. The multi-plate clutch mechanism 27 is of a hydraulic type, and the distribution of the driving force to the left and right wheels can be adjusted by adjusting the hydraulic pressure. The hydraulic system of the multi-plate clutch mechanism 27 of this, together with the hydraulic system of the multi-plate clutch mechanism 24 of the front and rear driving force control apparatus described above, the driving force transmission amount
Adapted to be controlled by a controller 16 as control means, the driving force transmitting this controller 16
The driving force distribution device 60 is constituted by the means.

That is, the hydraulic system of the multi-plate clutch mechanism 27 and the hydraulic system of the multi-plate clutch mechanism 24 include a hydraulic chamber (not shown) attached to each clutch mechanism, an electric pump 28 and an accumulator 29 constituting a hydraulic source. And a clutch hydraulic control valve 61 for supplying this hydraulic pressure to the hydraulic chamber by a required amount. The opening of the clutch hydraulic pressure control valve 61 is controlled by the controller 16.

The controller 16 controls the opening of the clutch hydraulic control valve 61 based on information from the wheel speed sensor 17 and the steering angle sensor 18. Here, the main parts of the driving force distribution device 60 will be described. As shown in FIG. 2, an input shaft 62A provided at the rear end of the propeller shaft 62 to receive the rotational driving force, and an input shaft 62A from the input shaft 62A. A left wheel rotation shaft (drive shaft of the left rear wheel 6) 14 and a right wheel rotation shaft (drive shaft of the right rear wheel 7) 15 for outputting the generated driving force are provided, and the left wheel rotation shaft 14 and the right wheel rotation are provided. A driving force distribution device 60 is interposed between the shaft 15 and the input shaft 62A.

The driving force distribution device 60 has the following configuration, and allows the left wheel rotating shaft 14 and the right wheel rotating shaft 15 to be differential while allowing the left wheel rotating shaft 14 and the right wheel rotating shaft 1 to have the following configuration.
5 can be distributed to a required ratio. That is, the left wheel rotation shaft 14 and the input shaft 62
A, and between the right wheel rotation shaft 15 and the input shaft 62A,
A transmission mechanism 26 and a multi-plate clutch mechanism 27 are interposed, and the rotation speed of the left wheel rotation shaft 14 or the right wheel rotation shaft 15 is increased by the transmission mechanism 26 so that a hollow shaft as a driving force transmission auxiliary member is provided. It is conveyed to 63.

The multi-plate clutch mechanism 27 is interposed between the hollow shaft 63 and a differential case (hereinafter abbreviated as a differential case) 11A on the input shaft 62A side. By combining
A driving force is sent from the high-speed differential case 11A to the low-speed hollow shaft 63. This is because, as a general characteristic of the clutch plates disposed opposite to each other, the torque is transmitted from a higher speed to a lower speed.

Therefore, for example, when the multi-plate clutch mechanism 27 between the right wheel rotation shaft 15 and the input shaft 62A is engaged, the driving force distributed to the right wheel rotation shaft 15 is reduced to the input shaft 62A.
The driving force distributed to the left-wheel rotating shaft 14 decreases or increases by the amount of the increase or decrease in the route from the side.
The above-mentioned transmission mechanism 26 is constituted by a so-called double planetary gear mechanism in which two planetary gear mechanisms are connected in series, and the transmission mechanism 26 provided on the right wheel rotating shaft 15 will be described as an example as follows. Become.

That is, a first sun gear 26A is fixed to the right wheel rotating shaft 15, and the first sun gear 26A
A meshes with a first planetary gear (planetary pinion) 26B on its outer periphery. The first planetary gear 26B is integrally fixed to the second planetary gear 26D, and is pivotally supported by a non-rotating carrier 26F fixed to a casing (fixed portion) through a pinion shaft 26C provided on the carrier. . As a result, the first planetary gear 26B and the second planetary gear 26D perform the same rotation about the pinion shaft 26C.

Further, the second planetary gear 26D includes:
The second sun gear 26E is meshed with a second sun gear 26E pivotally supported by the right wheel rotation shaft 15, and is connected to a clutch plate 27A of the multi-plate clutch mechanism 27 via a hollow shaft 63. The other clutch plate 27B of the multi-plate clutch mechanism 27 is connected to the differential case 11A driven by the input shaft 62A.

In the structure of this embodiment, since the second sun gear 26E is formed to have a smaller diameter than the first sun gear 26A, the rotation speed of the second sun gear 26E is reduced through the planetary gears 26B and 26D. The transmission mechanism 26 is larger than the first sun gear 26A, and the transmission mechanism 26 functions as a speed increasing mechanism. Accordingly, when the rotation speed of the clutch plate 27A is higher than that of the clutch plate 27B and the multi-plate clutch mechanism 27 is engaged, a torque corresponding to the engaged state is input from the right wheel rotation shaft 15 side. The paper is fed to the shaft 62A side. For this reason, the driving torque from the input shaft 62A is
Will be more distributed.

On the other hand, the speed change mechanism 26 and the multi-plate clutch mechanism 27 provided on the left wheel rotating shaft 14 are similarly configured. Therefore, when it is desired to distribute the drive torque from the input shaft 62A to the right wheel rotating shaft 15, the multiple disc clutch mechanism 27 on the left wheel rotating shaft 14 is appropriately engaged in accordance with the degree of the distribution (distribution ratio). If it is desired to distribute more to the left wheel rotating shaft 14, the multiple disc clutch mechanism 27 on the right wheel rotating shaft 15 side is appropriately engaged in accordance with the distribution ratio.

At this time, since the multi-plate clutch mechanism 27 is of a hydraulic drive type, the state of engagement of the multi-plate clutch mechanism 27 can be controlled by adjusting the magnitude of the hydraulic pressure, and the input shaft 62A to the left wheel rotating shaft 14 or The amount of the driving force supplied to the right wheel rotating shaft 15 (that is, the ratio of the driving force to the right and left distribution) can be adjusted with appropriate accuracy. The left and right multi-plate clutch mechanisms 27 are set so as not to be completely engaged with each other. When one of the left and right multi-plate clutch mechanisms 27 is completely engaged, the other multi-plate clutch mechanism 27 slips. Is to occur.

Next, the rear wheel steering device 20 of the present device will be described.
Co as A and the secondary steering mechanism 20B and the rear-wheel steering amount control means
Controller 16 . The main steering mechanism 20A is configured to provide a steering angle δ at a predetermined front-rear steering angle ratio to the rear wheels in accordance with the front wheel-side steering angle δf input by the steering wheel 8.
m. And in this embodiment,
When the handle 8 is rotated, the rotation is transmitted to the front wheel side steering gear box 21, and the front wheels are steered via left and right tie rods 21A and 21B provided in the front wheel side steering gear box 21. ing. The outer ends of the tie rods 21A and 21B are attached to a knuckle arm (not shown) of the front wheel by using, for example, a ball joint or the like. It is designed to steer.

On the other hand, a steering shaft 8A for rear wheel steering is provided from the front wheel side steering gear gear box 21 toward the rear wheel side, and the rotation of the steering wheel 8 is also transmitted to the steering shaft 8A. It has become. A steering gear box 23 for rear wheel steering is provided at the rear end of the steering shaft 8A, and the steering angle of the steering wheel 8 input from the steering shaft 8A is reduced at a predetermined reduction ratio to rear left and right. The wheels 6 and 7 are steered.

The rear-wheel steering steering gear box 23 comprises a pinion gear 23A and a rack 23B. Both ends of the rack 23B are provided with rear wheels for transmitting the steering angle to the rear left and right wheels. Wheel side tie rod 2
3C and 23D are provided. The rotation angle input from the steering shaft 8A rotates the pinion gear 23A provided in the rear-wheel steering steering gear box 23 to transmit the steering angle to the rack 23B. Further, by appropriately adjusting the number of teeth of the rack 23B and the pinion gear 23A, the rotation angle input from the steering shaft 8A is reduced.

The rear wheel tie rods 23C, 23D
End of the vehicle outside of the rear left and right wheels 6, 6 like the front wheel side
7 is attached to the knuckle arm 7 (not shown) using, for example, a ball joint or the like, so that the rear left and right wheels are steered at a steering angle δm. Here, the control characteristics of the main turning mechanism 20A are of a vehicle speed sensitive type as shown in the map of FIG. 7, and the front wheel side left / right wheel turning angle δf and the rear wheel side left / right wheel turning angle δm are determined according to the vehicle speed. The steering angle ratio changes.

The main steering mechanism 20A of the rear wheel steering device 20 includes:
With the above configuration, the rear wheels are steered at a predetermined turning angle δm with respect to the turning angles δf of the front wheels. At this time, the rear left and right wheels 6, 7 are steered with respect to the front left and right wheels 4, 5 in accordance with the map shown in FIG. Next, the sub-steering mechanism 20B of the rear wheel steering device 20 will be described.
For the rear left and right wheels 6, 7 mechanically steered by 0A, the turning angle δm is corrected in accordance with the running state of the vehicle in conjunction with the driving force distribution device 60 described above. .
In particular, here, when the main steering mechanism 20A is steering in phase, the auxiliary steering mechanism 20B can slightly correct the phase to the opposite phase side.

Here, the configuration of the auxiliary turning mechanism 20B will be described. A power cylinder 23E integrated with a rack 23B is provided in a steering gear box 23 for rear wheel steering. And this cylinder 23
In E, oil chambers 30, 31 partitioned by a spool 23F to the left and right are provided. When hydraulic oil is not supplied to the oil chambers 30, 31, the spool 23F is always positioned at the center in the cylinder 23E. The left and right oil chambers are provided with return springs 23G and 23H, respectively.

In this manner, the position of the rack 23B is adjusted according to the magnitude of the hydraulic pressure supplied to the left and right oil chambers 30, 31 in the cylinder 23E. In other words, when this hydraulic oil is driven, the left and right oil chambers 30, 31
The spool 23F moves in accordance with the magnitude of the hydraulic pressure of the hydraulic oil against the urging forces of the return springs 23G and 23H in which the forces are balanced, and the tie rods 23C and 23D move in the cylinder 23E. It has become.

For example, the main steering mechanism 20A controls the rear wheels 6,
7 is given a steering angle δm to the right, the pinion gear 2
By 3A, the rack 23B and the power cylinder 23E move to the left as a unit. Then, the auxiliary steering mechanism 20
B, the rear wheels 6, 7 are corrected to the opposite phase by the steering angle δρ with respect to the steering angle δm in accordance with the running state of the vehicle.
A predetermined amount of hydraulic oil is supplied to the left oil chamber.

When hydraulic oil is supplied to the left oil chamber, the spool 23F moves to the right by this oil pressure,
The tie rods 23C and 23D steer the left and right rear wheels 6 and 7 to the left so that the steering angle δm is corrected to the opposite phase. Thus, the actual rear wheel turning angle δr
Are the turning angle δm of the main turning mechanism 20A and the sub turning mechanism 2
The steering angle is obtained from the difference from the steering angle δρ due to 0B, and the steering is turned to the same phase by this steering angle δr (= δm-δρ).

The control characteristic of the auxiliary turning mechanism 20B is as follows.
This is shown in the map of FIG. That is, the sub steering mechanism 20B can correct the range shown in FIG. 6 for the steering angle δm mechanically given by the main steering mechanism 20A. By the way, the auxiliary steering mechanism 20B
Is controlled by the hydraulic pressure of the hydraulic oil, and this hydraulic system is arranged in the vehicle integrally with the hydraulic system of the multi-plate clutch mechanism 27 of the driving force distribution device 60.

The hydraulic system of the auxiliary steering mechanism 20B is the same as the multi-plate clutch mechanism 2 of the driving force control device 60 described above.
The controller 16 is controlled together with the hydraulic systems 4 and 27. That is, this controller
16 also functions as a rear wheel steering amount control means.
-ing That is, the hydraulic system of the sub-steering mechanism 20B includes the oil chambers 30 and 31 and the electric pump 2 that constitutes a hydraulic source.
8 and the accumulator 29 and the oil pressure
And a clutch oil pressure control valve 61 for supplying a required amount to 0 and 31. The opening of the clutch hydraulic control valve 61 is controlled by the controller 16. The controller 16 opens the clutch hydraulic control valve 61 based on information from the wheel speed sensor 17 and the steering angle sensor 18. The degree is controlled.

In this rear-wheel steering system linked to driving force distribution,
A control signal for controlling the opening of the clutch hydraulic control valve 61 is set by the controller 16 based on information from the wheel speed sensor 17 and the steering angle sensor 18. Here, the configuration of the controller 16 will be described. A part of the controller 16 includes a target yaw rate calculating means 22 for calculating a target yaw rate based on steering angle information and a processing device 25 for setting a control amount. Outputs a control signal for controlling the distribution of the driving force between the left and right wheels and a control signal for controlling the auxiliary turning mechanism 20B.

As shown in FIG. 1, the vehicle has a vehicle speed sensor 17 as vehicle speed detecting means for detecting the vehicle speed of the vehicle.
And a steering angle sensor 18 as steering angle detecting means for detecting a steering angle of the steering wheel, and a yaw rate sensor 19 as actual yaw rate detecting means for detecting an actual yaw rate of the vehicle. After the information is input to the controller 16, the controller 16 performs necessary calculations based on the respective detection signals to control the control amounts of the adjusting units 24 and 27 and the auxiliary steering mechanism 20 </ b> B.
Is obtained, and the set control signal is sent to the clutch hydraulic control valve 61. Then, a predetermined amount of operating oil pressure is supplied to the center differential limiting mechanism 24 and the multi-plate clutch mechanism 27 according to the map of FIG.

The vehicle speed sensor 17 is connected to each drive shaft 12,
13, 14, and 15, respectively, so that the rotation state of the drive shafts 12, 13, 14, and 15, that is, the wheel speeds of the wheels 4, 5, 6, and 7 can be detected. ing. And in this controller 16,
Based on the information from each sensor, a control signal for controlling the distribution of the driving force of the left and right wheels and a control signal for controlling the auxiliary steering mechanism 20B are output with reference to the actual yaw rate.

That is, in the processing device 25, each control command value E to the driving force distribution device 60 and the sub-steering mechanism 20B according to the yaw rate deviation and the differential value of the yaw rate deviation.
L and ER are output. Here, the means for setting the control command values EL and ER in the processing device 25 will be described. First, the front wheel side turning angle (actual steering angle) δf detected by the steering angle sensor 18 and the main turning mechanism 20A
, The four wheel speeds V4, V5, V6, V7 detected by the vehicle speed sensor 17 and the actual yaw rate Y detected by the yaw rate sensor 19 are input to the controller 16. Has become.

Next, the target yaw rate Y ^* is calculated by the target yaw rate calculating means 22 according to the following equation (1). Y ^* = V · (δf−δm) / [L (1 + A · V ² )] (1) where V is an average value of wheel speeds V4, V5, V6, and V7,
L is the wheelbase of the vehicle, and A is the stability factor. The stability factor A is one of the vehicle speed sensitive elements, similarly to the feedback gains G1 and G2 described later, and its value is determined according to, for example, a graph shown in Map 1 of FIG.

Then, the yaw rate deviation ΔY, which is the deviation between the target yaw rate Y ^* and the actual yaw rate Y, is given by equation (2).
And the yaw rate deviation differential value Δ
Y 'is calculated according to equation (3). ΔY = Y ^* −Y (2) ΔY ′ = dΔY / dt (3) and Using the yaw rate deviation .DELTA.Y and the yaw rate deviation differential value .DELTA.Y ', the processor 25 issues command values EL and ER.
Is calculated according to, for example, the following equations (3) and (4). EL = G1 × ΔY + G2 × ΔY ′ (3) ER = −G1 × ΔY−G2 × ΔY ′ (4) Here, G1 and G2 are: This is a vehicle speed sensitive element called feedback gain.
The values of 1 and G2 are determined according to, for example, a graph as shown in Map 2 of FIG.

The command value EL is determined by the driving force distribution device 60.
Is a signal indicating the magnitude of the hydraulic pressure supplied to the left-wheel-side multi-plate clutch mechanism 27. In the sub-steering mechanism 20B, the magnitude of the hydraulic pressure supplied to the left oil chamber 30 in the cylinder 23E is FIG. Similarly, the command value ER is a signal indicating the magnitude of the hydraulic pressure supplied to the right-wheel-side multi-plate clutch mechanism 27 in the driving force distribution device 60, and the cylinder 2 in the sub-steering mechanism 20B.
It is a control signal indicating the magnitude of the hydraulic pressure supplied to the right oil chamber 31 in 3E.

Then, the above command value E from the processing unit 25 is obtained.
The control signals for L and ER are sent to the clutch hydraulic control valve 61, and a predetermined amount of operating hydraulic pressure is supplied to the multiple disc clutch mechanism 27 and the auxiliary turning mechanism 20B according to the map shown in FIG. Then, such a control operation is repeated at a predetermined cycle. As a result, control signals for the command values EL and ER are sent from the controller 16 to the clutch oil pressure control valve 61, and a predetermined operating oil pressure is applied to the driving force distribution device 6
0 and output to the auxiliary steering mechanism 20B, the driving force transmitted to the left and right wheels is adjusted to a required state, and the steering angle on the rear wheel side is also controlled to correspond to the driving state of the vehicle. The driving force distribution is performed.

Here, in the multi-plate clutch mechanism 27,
The driving force corresponding to the control signals of the command values EL and ER is determined by, for example, a map shown in FIG. In this map, a neutral dead zone width α is provided, and command values EL, E
When R is a small value in the dead zone, the driving force distribution between the left and right wheels is set not to change. This neutral dead zone is provided in a region where EL and ER are close to 0, and when noise is mixed into a signal input to each of the sensors 17, 18, and 19 during traveling of the vehicle due to disturbance from a road surface or the like. In addition, it is provided to stabilize control by suppressing excessive control for a minute control signal output by the noise.

Therefore, when EL and ER are small values near 0, the driving torque corresponding to the control signal command values EL and ER is set to 0, and the driving force distribution between the left and right wheels is not changed. It has become. A vehicle with a driving force distribution interlocking rear wheel steering device as one embodiment of the present invention,
Since the operation is performed as described above, for example, the command values EL and ER of the control signal are set according to the flowchart shown in FIG.

Referring to the flowchart of FIG. 3, first, in step S1, the front wheel turning angle (actual steering angle) δf, the rear wheel turning angle δm, and the wheel speeds V of the four wheels are set.
4, V5, V6, V7 and the actual yaw rate Y are input to the controller 16. Next, step S
At 2, the target yaw rate Y ^* is calculated according to equation (1) above.

Then, in step S3, the yaw rate deviation ΔY and the yaw rate deviation differential value ΔY 'are calculated according to the equations (2) and (3). Then, in step S4, the command values EL and ER are calculated according to the above equations (3) and (4) using the yaw rate deviation ΔY and the yaw rate deviation differential value ΔY '.

In step S5, the control signals of the above command values EL and ER are sent from the processing unit 25 to the clutch hydraulic control valve 61, and a predetermined operating oil pressure is applied to the multi-plate clutch mechanism 27 and the auxiliary turning mechanism 20B. It is supplied to. Then, such a control operation is repeated at a predetermined cycle. With such a function, at middle and high speeds, the rear wheels are steered to the same phase by the main steering mechanism of the rear wheel steering device, so that the responsiveness in the lateral acceleration (lateral G) direction is improved, and the center-of-gravity slip angle is improved. And the vehicle attitude during turning is stabilized.

Further, when the vehicle turns by the driving force distribution device 60, a torque difference is generated between the left and right wheels to generate a yaw moment, and the yaw rate of the vehicle is fed back so as to approach the target yaw rate, according to the steering state of the vehicle. Since the distribution of the driving force between the inner wheel and the outer wheel is adjusted, a turning moment in the direction in which the vehicle is going to turn is appropriately given.

The auxiliary turning mechanism 20B of the rear wheel steering device
As a result, the turning of the vehicle is promoted, the turning characteristics of the vehicle are improved, and the responsiveness in the yaw direction and the responsiveness in the lateral G direction are improved. By neutralizing the steering characteristics of the vehicle, the limit value of the turning performance of the vehicle is improved, and the vehicle controllability near the limit at the time of turning can be improved.

Further, the turning characteristics of the vehicle, for example, understeer and oversteer can be made closer to ideal steer characteristics such as neutral steer. Further, since the yaw rate feedback control and the rear wheel steering angle control are controlled using the same hydraulic system, the hydraulic system of the present apparatus can be operated in a small, simple, and reliable manner.

In this embodiment, the driving force distribution device 6
Although a hydraulic multi-plate clutch mechanism 27 is provided as 0, the driving force distribution device 60 includes a friction clutch, a VCU (Viscous Coupling Unit), and an HCU (hydro Other couplings such as a rick coupling unit) can also be used.

In the case of a friction clutch, it is conceivable that the engagement force is adjusted by hydraulic pressure or the like in the same manner as in the multi-plate clutch mechanism. It is conceivable to install it in the direction of torque transmission. Also, this VCU and HCU
Although a conventional type having a constant power transmission characteristic can be considered, a type in which the engagement force can be adjusted and the power transmission characteristic can be adjusted by hydraulic pressure, electromagnetic force, or the like is suitable.

Further, the main steering mechanism 20A does not need to have the control characteristics as shown in the map of FIG. 7, and for example, there is no problem even if the main steering mechanism 20A has the control characteristics so as not to turn to the opposite phase. . It should be noted that a driving force distribution device 60 is added to the front differential 10, and the two driving force distribution devices 60 on the front side and the rear side are simultaneously controlled to adjust the driving force distribution between the left and right wheels. It is also conceivable to configure it.

With such a structure, the turning performance of the vehicle can be further improved by controlling the distribution of the driving force to the left wheel side and the right wheel side.

[0055]

As described in detail above, according to the vehicle with the driving force distribution interlocking type rear wheel steering device according to the first aspect of the present invention, the driving force distribution for distributing and adjusting the driving force from the engine to the left and right wheels . Device and a predetermined amount of steering corresponding to the amount of steering of the vehicle.
In a vehicle provided with a rear wheel steering device for steering a rear wheel, the driving force distribution device includes a left wheel side rotation shaft and a right wheel side rotation shaft.
The rotation speed of one of the shaft and the left wheel side
Drive force is transmitted to either the shaft or the right wheel side rotation shaft
Driving force transmitting means, and driving by the driving force transmitting means
Driving force transmission amount control means for controlling the amount of force transmission,
The rear wheel steering device transmits the driving force of the driving force distribution device.
Rear wheel that controls the amount of steering of the rear wheel steering device according to the amount of steering
The configuration of being provided with a steering amount control means, turning
At the time, the driving force distribution control between the left and right wheels is performed, for example, by distributing a larger driving force to the outer wheel side of the vehicle than the inner wheel side, the steering angle corresponding to the steering wheel steering angle on the rear wheel side is set as described above. While turning with the steering angle corrected according to the driving force distribution,
The turning performance can be improved.

Specifically, for example, by a rear wheel steering device,
By turning the rear wheels to the same phase, the response in the lateral G direction is improved, the center of gravity slip angle is reduced, and the stability of the vehicle at the time of turning is improved. Further, the control and the rear wheel steering equipment of reverse phase correction control of the drive force distribution device, yaw moment is generated caused a torque difference between the left and right wheels and the vehicle is turning, yaw
Improved the responsiveness of the rectangular direction, it is improved turning characteristics of the vehicle
You.

[0057] Further, as the steering characteristic of the vehicle by the drive force distribution device by neutral steer by being improved limit value of turning performance of the vehicle, it is possible to improve the vehicle control of near the limit in cornering Has advantages
You. In particular, like the vehicle with the driving force distribution interlocking rear wheel steering device according to the second aspect of the present invention, both the driving force distribution device and the auxiliary turning mechanism are configured to be driven by hydraulic pressure, With the configuration in which the driving force distribution device and the auxiliary turning mechanism are set to be controlled by the same hydraulic pressure, the hydraulic system of the device can be made small and simple, and the driving force distribution device and the auxiliary Interlocking with the rudder mechanism can be ensured.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a vehicle with a driving force distribution interlocking rear wheel steering device as one embodiment of the present invention.

FIG. 2 is a schematic diagram showing a main configuration of a driving force transmission system in a vehicle with a driving force distribution interlocking type rear wheel steering device as one embodiment of the present invention.

FIG. 3 is a flowchart showing an operation of a main part in a vehicle with a driving force distribution interlocking type rear wheel steering device as one embodiment of the present invention.

FIG. 4 is a map related to control amount setting in a vehicle with a driving force distribution interlocking type rear wheel steering device as one embodiment of the present invention.

FIG. 5 is a map relating to a control amount setting in a vehicle with a driving force distribution interlocking type rear wheel steering device as one embodiment of the present invention.

FIG. 6 is a map related to control amount setting in a vehicle with a driving force distribution interlocking type rear wheel steering device as one embodiment of the present invention.

FIG. 7 is a map related to control amount setting in a vehicle with a driving force distribution interlocking type rear wheel steering device as one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Driving force transmission system 2 Engine 3 Center differential 4, 5 Front wheel 6, 7 Rear wheel 8 Handle 8A Steering shaft 10 Front differential 11 Rear differential 11A Differential case 12, 13, 14, 15 Drive shaft 16 Controller as control means 17 Wheel speed sensor Reference Signs List 18 steering angle sensor 19 yaw rate sensor 20 rear wheel steering device 20A main steering mechanism 20B auxiliary steering mechanism 21 front wheel side steering gear gear box 21A, 21B front wheel side tie rod 22 target yaw rate calculation means 23 rear wheel side steering gear gear box 23A Pinion gear 23B Rack 23C, 23D Rear wheel side tie rod 23E Power cylinder 24 Center differential limiting mechanism 25 Processing unit 26 Transmission mechanism 26A First sun gear 26B First planetary gear 26C Pini Shaft 26D second planetary gear 26E second sun gear 26F carrier 27 multi-plate clutch mechanism 27A clutch plate 27B clutch plate 28 electric pump 29 accumulator 30, 31 oil chamber 60 driving force distribution device 61 clutch hydraulic pressure control valve 62 propeller shaft 62A input shaft 63 hollow shaft

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI B62D 13:00

Claims (2)

(57) [Claims] 1. A vehicle comprising: a driving force distribution device for distributing and adjusting a driving force from an engine to left and right wheels; and a rear wheel steering device for steering rear wheels by a predetermined steering amount corresponding to a steering amount of the vehicle. In the above, the driving force distribution device is configured to control the rotation speed of one of the left wheel side rotation shaft and the right wheel side rotation shaft.
And change the position between the left wheel side rotation shaft and the right wheel side rotation shaft.
Drive force transmission means for transmitting the driving force to shift or other, drive controls the transmission of driving force by the driving force transmitting means
Power transmission amount control means, wherein the rear wheel steering device corresponds to the rear wheel corresponding to the driving force transmission amount of the driving force distribution device.
A rear wheel steering amount control means for controlling the steering amount of the steering device is provided.
Characterized in that it is configured Ete, driving force distribution interlocked rear wheel steering device with the vehicle. 2. The vehicle according to claim 1, wherein the rear wheel steering device controls a steering amount of the vehicle.
Main steering mechanism that steers rear wheels at a specified front-rear steering angle ratio
And an auxiliary that can additionally correct the turning of the main turning mechanism.
With a steering mechanism, the driving force transmission device and the sub-steering mechanism share a common hydraulic pressure.
The vehicle with a driving force distribution interlocking rear wheel steering device according to claim 1, wherein the vehicle is configured to be controlled more .