JPH08324272A - Driving force distributing device of four-wheel drive car - Google Patents

Abstract

PURPOSE: To secure traveling stability when an ABS and torque distribution control are performed. CONSTITUTION: In a four-wheel drive car mounted with an antilock brake system to control so as to become stable braking force by avoiding a lock of wheels l and 2, the four-wheel drive car is provided with a clutch mechanism 9 to transmit driving force from an engine 3 to front and rear wheels l and 2 in the ratio distribution determined according to its fastening force and a controller 45 which actuates the clutch mechanism 9 so as to become optimal fastening force on the basis of a speed difference between the front and rear wheels l and 2 at ordinary traveling time and fixes it to prescribed fastening force when the antilock brake system is actuated or puts a control width of the fastening force in a limited range.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving force distribution device for a four-wheel drive vehicle that appropriately distributes driving force from an engine to front and rear wheels.

[0002]

2. Description of the Related Art An anti-lock brake system (hereinafter referred to as ABS) which is recently installed in many vehicles.
Is to control a stable braking force by following the friction coefficient between the tire and the road surface while avoiding wheel lock during braking on a slippery road surface or the like.

On the other hand, four-wheel drive vehicles include a part-time system in which four-wheel drive and two-wheel drive are appropriately switched, and a full-time system in which four-wheel drive is always available. In general, the part-time method mechanically directly connects the front and rear wheels by manual operation as needed, and when the four wheels are on the road surface with the same friction coefficient,
The driving force (torque) distribution is proportional to the dynamic load distribution of the front and rear wheels, and even if one of the front and rear wheels slips, the driving force distribution will be in accordance with the grip force of the tire. In addition, the full-time system constantly transmits the driving force to the front and rear wheels while absorbing the difference in rotation between the front and rear wheels, and the fixed distribution type in which the driving force distribution between the front and rear wheels is always a constant ratio, and the road surface condition. There is a variable distribution system in which the distribution of driving force can be changed according to the driving conditions and the like.

In the variable distribution system for controlling the driving force distribution, the front and rear wheel speeds are detected by a vehicle speed sensor and the hydraulic multi-plate clutch is controlled based on the vehicle speed difference, or the amount of hydraulic load generated from the vehicle speed difference. The driving stability is ensured by changing the distribution of the driving force to the front wheels or the rear wheels depending on the difference between the two.

[0005]

By the way, in a four-wheel drive vehicle of a variable distribution system equipped with an ABS, when torque distribution control is performed during ABS operation, each performs control based on a separate detection value. However, there has been a problem that the drive system controls of the two may interfere with each other, resulting in a large change in the behavior of the vehicle.

Therefore, the present invention was devised to provide a driving force distribution device for a four-wheel drive vehicle capable of ensuring running stability when performing ABS and torque distribution control.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a four-wheel drive vehicle equipped with an anti-lock brake system for avoiding wheel lock and controlling a stable braking force, and a driving force from an engine is used as the fastening force. The clutch mechanism that transmits to the front and rear wheels with a ratio distribution determined according to
During normal driving, it is operated so that the optimum fastening force is obtained based on the speed difference between the front and rear wheels, and when the anti-lock brake system is operating, it is fixed to a predetermined fastening force or the control range of the fastening force is limited. And a controller to operate.

[0008]

With the above construction, the controller operates the clutch mechanism on the basis of the speed difference between the front and rear wheels during the normal running in which the ABS is not operating, and optimally distributes the driving force to the front and rear wheels. At the time of ABS operation, the clutch mechanism is fixed so as to have a preset predetermined engaging force, or the clutch mechanism is controlled so that the control range of the engaging force is limited to avoid mutual control interference. .

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

1 and 2 show an embodiment of a driving force distribution device for a four-wheel drive vehicle according to the present invention. The four-wheel drive vehicle 4 is provided with a part-time drive system that is manually switched to two-wheel drive (2H) and four-wheel drive high speed (4H) and low speed (4L).
The driving force from the engine 3 is transmitted to the rear propeller shaft 16 via the transfer portion 6 so that the rear wheels 2 are constantly driven, and the front wheels 1 are transferred from the transfer portion 6 to the front propeller shaft 33 when the shift lever 7 is operated. The driving force is transmitted to. A driving force distribution device that appropriately distributes the driving force includes a multi-plate clutch 9 that is a clutch mechanism provided in the transfer unit 6, and wheel speed sensors 43 and 44 for detecting the speeds of the front and rear wheels 1 and 2, respectively. , A controller 4 for appropriately operating the multi-plate clutch 9 based on the detection values of the wheel speed sensors 43, 44.
And 5 mainly.

The transfer section 6 includes a switching mechanism 8 for performing speed switching (4H-4L) in four-wheel drive by operating a shift lever 7, and a multi-plate clutch 9 for substantially distributing the driving force via the switching mechanism 8. It has and. The switching mechanism 8 appropriately connects an input shaft 10 connected to the engine 3 via the transmission 5 and a first intermediate shaft 52 connected to the rear propeller shaft 16 via a universal joint 51 via a planetary gear mechanism 53. They are connected, and the configuration will be described later. A small gear 18 forming a part of the final reduction gear unit 17 is attached to the output end of the rear propeller shaft 16, and the small gear 18 includes a differential case 19
Is meshed with a large gear 20 attached to. The large gear 20 transmits the rotational force to the rear wheel axle 22 and the rear wheel 2 via the left and right small differential gears 21.

The multi-plate clutch 9 comprises a plurality of inner plates 23 attached to the first intermediate shaft 52 and an outer plate 24 arranged between the inner plates 23.
The outer plate 24 is attached to the inner wall of the clutch housing 25 that covers the plates 23 and 24.
An outer cylinder portion 54 that extends coaxially with the first intermediate shaft 52 is attached to the front end of the clutch housing 25, and is rotatably formed with respect to the first intermediate shaft 52. The inner plate 23 and the outer plate 24 are pressed against each other in the clutch connecting direction by the magnetic force of the electromagnetic coil 26 fixed in the vicinity thereof. That is, the contact state between the inner plate 23 and the outer plate 24 changes according to the value of the current supplied to excite the electromagnetic coil 26, and the clutch engaging force (pressing force) is increased or decreased. Further, a sprocket 55 is attached to the front end of the outer tubular portion 54, and is connected to a sprocket 57 attached to the second intermediate shaft 56 via a chain 58. The second intermediate shaft 56 is provided in parallel with the first intermediate shaft 52, and is attached to the front propeller shaft 33 by the universal joint 5.
They are connected via 1. Front propeller shaft 3
A small gear 35 that constitutes the final reduction gear 34 is attached to the front end of 3, and the driving force from the small gear 35 is the large gear 36,
The front wheel axle 39 and the front wheel 1 are rotated by being sequentially transmitted to the differential case 37 and the small differential gear 38. That is, the engagement force of the multi-plate clutch 9 is changed by controlling the power supply to the electromagnetic coil 26, and the torque is transmitted to the front and rear wheels 1 and 2 at a ratio distribution (0: 100 to 50:50) determined according to the engagement force. It can be done.

Then, the controller 45 mainly operates the electromagnetic coil 2 based on the detection values of the wheel speed sensors 43 and 44.
The power supply to 6 is controlled. The wheel speed sensors 43 and 44 face the front wheel speed sensor 43 facing the disc (gear) 41 with a protrusion attached to the second intermediate shaft 56 and the disc 42 with a protrusion attached to the first intermediate shaft 52. And the rear wheel speed sensor 44. Each of the disks with protrusions 41, 42 has a plurality of protrusions formed at equal intervals on the periphery thereof. Wheel speed sensor 43,44
The sensor senses the protrusion and outputs a pulse signal each time the protrusion passes, which is input to the input unit 46 of the controller 45. The input information is arithmetically processed by the arithmetic processing unit 47 to determine the optimum amount of current (voltage duty ratio) to be supplied to the electromagnetic coil 26. For example, when there is a speed difference between the front and rear wheels 1 and 2, it is considered that slip has occurred during traveling, and the voltage duty ratio that is the engagement force of the multi-plate clutch 9 for canceling this is determined and the output unit Four
Output from 8.

The wheel speed sensor 4 is connected to the input section 46.
In addition to the pulse signals from 3,44, the brake signal and A
The BS operation signal is input. That is, a brake sensor 72 for detecting the depression of the brake pedal 71 and an ABS control unit 73 are connected to the controller 45. The ABS control unit 73 appropriately adjusts the braking force of each of the front and rear wheels 1 and 2 to prevent locking based on a vehicle G sensor (acceleration sensor), an engine rotation sensor (not shown), and the like. At the same time when the control is started, an ABS operation signal is output to the controller 45. The brake signal is input to the controller 45 in order to confirm that the ABS operation signal is due to the driver's intention (brake operation).

When the brake signal and the ABS actuating signal are input, the arithmetic processing section 47 controls the engagement force of the multi-plate clutch 9 so that the change in the torque distribution is reduced without performing the normal torque distribution control. The fastening force of the multi-plate clutch 9 is fixed so that the width is narrowed or the preset torque distribution is achieved. The value of the change width of the torque distribution or the value of the fixed torque distribution is determined by tuning with the vehicle to be mounted so that the torsional vibration does not occur during ABS operation and the most stable running is obtained. And The output signal 48 of the controller 45 outputs a mode signal indicating the driving state (2H, 4H) of the vehicle to the ABS control unit 73.
Information from position sensors 61 and 62 that detect the position of the shift lever 7 is input to the input unit 46 of the controller 45.
Is operated to the four-wheel drive side, the multi-plate clutch 9 is operated to switch to the four-wheel drive mode (4H), and
The torque distribution control is started.

Next, the structure of the switching mechanism 8 of the transfer section 6 will be described. The switching mechanism 8 includes an input spline 11 and an input gear 12 provided on the input shaft 10, a planetary gear 14 that meshes between the input gear 12 and a fixed gear 13, which are sun gears, and a rotation of the planetary gear 14. And a cylindrical gear 15 that rotates around the input shaft 10. Then, by operating the shift lever 7, the input spline 11 or the cylindrical gear 15 is attached to the input end of the first intermediate shaft 52, and the drive spline 6 is attached.
3 is selectively connected via a slidable shift sleeve 64. FIG. 1 shows a state in which the high mode (4H) is selected, and the shift sleeve 64 connects the input spline 11 and the drive spline 63 so that the input shaft 10 becomes the first intermediate shaft 5
Directly connect to 2. When the low mode (4L) is selected, the shift sleeve 64 connects the cylindrical gear 15 and the drive spline 63 to rotate the first intermediate shaft 52 at a reduced speed. The high mode (4H) is selected when the road surface is relatively slippery such as snowy roads and muddy roads in addition to normal driving. Selected in situations that require

Further, the clutch housing 25 and the first intermediate shaft 52 are provided with splines 27 and 28 for direct connection which are mechanical locks. These direct connection splines 27, 28 are connected to each other by a slidable connection shift sleeve 29 when the low mode (4L) is selected. Due to this connection, the clutch housing 25 becomes the first intermediate shaft 52 (rear propeller shaft 1
6), the torque distribution control by the multi-disc clutch 9 is not performed. Two-wheel drive mode (2
When H) is selected, the positions of the shift sleeve 64 and the connecting shift sleeve 29 are the same as those in the high mode (4H), but the multi-plate clutch 9 is in a disengaged state, so that the front propeller shaft 33 does not move. There is no drive transmission. The front wheel drive system (front propeller shaft 33) in the clutch disengaged state is connected to the axle connecting / disconnecting mechanism 6.
It is held stationary by 5.

The axle connecting / disconnecting mechanism 65 is provided at a split position of the front wheel axle 39 which is split between the front wheel 1 and the final reduction gear 34, and splines attached to the opposite ends of the split axles 39a and 39b, respectively. 66 and 67, a connection shift sleeve 68 that connects and disconnects these splines 66 and 67 by sliding, and a connection shift sleeve 6
It is mainly configured by an actuator 69 for operating 8 appropriately. By disconnecting the connection between the splines 66 and 67 in the two-wheel drive (2H) by the operation signal of the controller 45, the rotation from the front wheels 1 due to traveling becomes idle in the final reduction gear 34, and the rear propeller shaft 33. It will not be transmitted to. With this configuration, it is possible to avoid wasteful energy consumption associated with traveling. The actuator 69 may be configured by an air cylinder, a dashpot that operates by negative pressure, or the like.

Next, the operation of this embodiment will be described.

When the shift lever 7 is switched from the two-wheel drive (2H) to the four-wheel drive (4H), the controller 45 detects this by the signals from the position sensors 61 and 62, and first, a predetermined voltage duty ratio. Then, the electromagnetic coil 26 is excited. Due to this excitation, the multi-plate clutch 25 exerts an appropriate fastening force, and the first intermediate shaft 52
Transmits torque to the second intermediate shaft 56 to rotate the stationary front propeller shaft 33. When the rotation of the front propeller shaft 33 is sufficiently increased, the axle connecting / disconnecting mechanism 65 is operated to connect the front wheel 1 (front wheel axle 39) and the front propeller shaft 33 via the final reduction gear 34, and the front wheel speed sensor 43 and the rear wheel speed sensor 43 Torque distribution control (main control) is started based on the front and rear wheel speed detection values detected by the wheel speed sensor 44. That is, when there is a speed difference between the front and rear wheels 1 and 2, it is considered that slip has occurred during traveling, and the voltage duty ratio that is the engagement force of the multi-plate clutch 9 that cancels this is determined and the current The electromagnetic coil 26 is excited with a value to adjust the fastening force of the multi-plate clutch 25.

In this torque distribution control, first, AB
It is determined whether S is operating. That is, as shown in FIG. 3, the controller 45 includes the brake sensor 72.
When the brake ON signal is input from the ABS control unit 73 and the ABS operation signal is input from the ABS control unit 73, the control width of the torque distribution by the torque distribution control based on the front / rear wheel speed difference is suppressed to a limited range or the torque is controlled. The distribution control is not performed, and the engagement force of the multi-plate clutch 9 is controlled or fixed with a preset most preferable torque distribution during ABS operation.

As described above, the torque distribution control is performed by operating the multi-plate clutch 9 so that the optimum engaging force is obtained based on the speed difference between the front and rear wheels 1 and 2, and the control width of the torque distribution is controlled during the ABS operation. Since the front and rear wheels 1 and 2 are driven within a limited range or at a preset fixed ratio distribution, it is possible to prevent the torque distribution control and the braking force control of the ABS from interfering with each other, and the behavior of the vehicle. Change can be minimized. That is, further improvement in running stability is achieved. Further, the present invention is basically realized by only partially improving the controller, and is extremely versatile.

In this embodiment, the case where the present invention is applied to the switching type four-wheel drive vehicle is shown, but it is also widely applied to the full-time type four-wheel drive vehicle which controls the torque distribution between the front and rear wheels. It is what is done.

[0024]

In summary, according to the present invention, it is possible to prevent an excessive behavior change of the vehicle due to the mutual interference of the ABS and the torque distribution control, and it is possible to further improve the running stability. To do.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of a driving force distribution device for a four-wheel drive vehicle according to the present invention.

FIG. 2 is a plan view showing a specific configuration of a main part of FIG.

FIG. 3 is a flowchart for explaining the operation of FIG.

[Explanation of symbols]

 1 front wheel (wheel) 2 rear wheel (wheel) 3 engine 9 multi-plate clutch (clutch mechanism) 43 front wheel speed sensor (wheel speed sensor) 44 rear wheel speed sensor (wheel speed sensor) 45 controller 73 ABS control unit

 ─────────────────────────────────────────────────── ———————————————————————————————————————————————————————————— Inventor Will Watson Sterling Heights, Michigan, USA 18 1/2 Mile Road 6690 Borg Warner Automotive Inc. Powertrain Systems Corporation (72) Inventor Dan Showarter, Sterling Heights, Michigan, USA 18 1/2 Mile Road 6690 Borg Warner Automotive Inc. Powertrain Systems Corporation

Claims (1)

[Claims] 1. In a four-wheel drive vehicle equipped with an anti-lock brake system for avoiding wheel lock and controlling a stable braking force, front and rear wheels are distributed in proportion to the driving force from an engine depending on the fastening force. And the clutch mechanism that is transmitted to the clutch mechanism so as to obtain an optimum engaging force based on the speed difference between the front and rear wheels during normal traveling, and a predetermined engaging force when the antilock brake system is operating. A driving force distribution device for a four-wheel drive vehicle, comprising: a controller that limits a control width of a fixing or fastening force.