JPH0220432A - Torque distribution controller of four-wheel drive vehicle - Google Patents

Abstract

PURPOSE:To enable the torque distribution taking consideration of the steering characteristics and the straight drive stability of a vehicle when it runs at a high speed by compensating the torque distribution determined by the acceleration according to the running speed. CONSTITUTION:A torque distribution changing means D varies the torque distribution between the front wheels B, B and rear wheels C, C by applying a braking force to either front or rear wheels. A torque distribution control means F operates the torque distribution changing means D to change the torque distribution rate for the front and the rear wheels according to the acceleration speed detected by an acceleration detecting means E. A torque distribution compensating means H compensates the torque distribution according to the accelerated speed detected by a speed detecting means G.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an I-luke distribution control device that controls the torque distribution ratio between front and rear wheels in a four-wheel drive vehicle.

(Prior Art) In a four-wheel drive vehicle in which front wheels and rear wheels are driven by engine output, it is desirable to variably control the ratio of torque distribution to each wheel to an optimal ratio depending on the driving condition. According to Japanese Patent Application Laid-Open No. 60-248440,
The vehicle is equipped with a torque distribution changing means that changes the torque distribution of these wheels by controlling the braking force to each wheel, and when any wheel slips, the slip is eliminated by reducing the torque distribution to that wheel. , a vehicle is shown in which the running power of the vehicle as a whole is increased by -1.

In addition, in this type of four-wheel drive vehicle, it is considered to be equipped with a torque distribution changing means as described in "-" to control the torque distribution between the front and rear wheels to be changed according to the acceleration during acceleration. It is being This is because the torque distribution on the f&wheel side is increased in response to the load shift to the rear wheels with acceleration, so the driving force of the front wheels, whose load is reduced during acceleration, is reduced. As the driving force of the rear wheels increases as the load increases, the loads of the front and rear wheels always correspond to the driving force, and the driving force is transferred to the vehicle without causing slippage between the front and rear wheels. As a result, the acceleration performance of the vehicle will be improved.

(Problem to be solved by the invention) By the way, the above-mentioned system in which the torque distribution to the rear wheels is increased according to the acceleration is an improvement in improving the stability of the vehicle at high speeds. In other words, in general, when the torque distribution to the rear wheels is increased, the steering characteristics tend to oversteer, reducing driving stability. This is because the slip limit with respect to the traction force acting on the wheel, especially the lateral force, decreases, and this decrease in the slip limit becomes more pronounced as the driving force of the wheel increases.

Therefore, as described above, the present invention aims to improve the propulsion efficiency or acceleration performance of the vehicle by variably controlling the torque distribution between the front and rear wheels according to the acceleration. The objective is to also improve stability I11:.

(Problems and Means for Solving the Problems) In order to solve the above problems, the present invention uses the following means.

That is, the I/Lux distribution control device for a four-wheel drive vehicle according to the present invention is configured to drive front wheels B, B and rear wheels C, C by the output of engine A, as shown in FIG. In addition, in a four-wheel drive vehicle equipped with l-lux distribution changing means that changes the torque distribution between the front and rear wheels by applying braking force to either the front wheels B, B or the rear wheels C1C, for example, acceleration detection means E for detecting the acceleration of the vehicle;
and an I-lux distribution control stage F which operates the l-lux distribution changing means to change the torque distribution of the rear wheels in accordance with the acceleration detected by the detection means E, and Furthermore, vehicle speed detection means G for detecting the speed of the vehicle
and 1-herk distribution correction means H for correcting the torque distribution according to the acceleration according to the vehicle speed detected by the detection means G.

(Function) According to the above configuration, during acceleration, the torque distribution control means F changes the torque distribution between the front and rear wheels according to the acceleration. By operating the torque distribution changing means to increase the distribution, the driving force of both wheels will be increased or decreased in response to changes in the loads on the front wheels B, B and rear wheels C1C due to load transfer due to acceleration. . Therefore, the load and driving force of both the front and rear wheels correspond to each other, and the driving force is effectively used as propulsive force without causing slippage, and the acceleration performance of the vehicle is improved.

In addition to the f:1-luke distribution control according to the acceleration as described in ``-'', the torque distribution correction means H performs correction control of the torque distribution according to the vehicle speed, specifically, when the vehicle speed is high, the front wheels B, 130! ! Since correction control is performed in the direction of increasing the +1-lux distribution, stability at high vehicle speeds is improved while ensuring good acceleration performance.

(Example) Examples of the present invention will be described below.

First, the overall configuration of this embodiment will be explained with reference to FIG.
The vehicle according to the present embodiment is a four-wheel drive vehicle in which the left and right front wheels 2.3 and the left and right rear wheels 4.5 are both drive wheels, and the output of the engine 6 is transmitted through the transmission 7. The vehicle is inputted to the front wheel/sphere device 8 and is divided into the front wheels 2 and 3 side and the rear wheel 4.5 side. And front wheels 2 and 3
f! The output to the first propeller shaft 9 extending forward from the side of the transfer device 8, the front wheel differential device 10, and the left and right front wheel drive shafts 1.1. ．． 12 to the left and right front wheels 2.3, and the output to the rear wheels 4.5 is transmitted to the 21st transfer device 8 extending rearward from the transfer device 8.
The power is transmitted to the left and right rear wheels 4 and 5 via the zero-bell shaft 13, the rear wheel differential 14, and the left and right rear wheel drive shafts 15 and 16.

The left and right front wheel drive shafts 11, ]2 and the left and right rear drive shafts), 5.16 include a disc rotor that rotates integrally with these, and a disc rotor that rotates when braking pressure is supplied. Brake devices 17, 18 and 19, 20 made of galipers or the like are respectively provided to brake the rotation of the disc rotor. These brake devices 17 to 20 are actuated by the braking pressure generated in the mask cylinder when the brake pedal is depressed. On the other hand, the separately provided brake controller 2
], the braking operation is also controlled by l- via a braking pressure control valve to be described later.

Furthermore, in this heavy vehicle 1, an intake passage 2 of the engine 6 indicated by L is provided.
An actuator 24 that opens and opens a throttle valve 23 provided in the engine 2, and an engine controller 25 that controls the operation of this actuator 24 are provided. Based on the signal, the opening degree of the throttle valve 23 is controlled according to the accelerator opening degree.

By performing pre-play control and engine control via the brake controller 21 and the engine controller 1-roller 25, the front wheel 2.3 and the rear wheel 4.5
A torque distribution controller 27 is provided to control torque distribution to the torque control I/roller 27, and receives a signal from the accelerator opening sensor 26 and a signal from the steering angle sensor 28 for torque distribution control during cornering. , a signal from a vehicle speed sensor 29 that detects the speed of the vehicle 1, and signals from various sensors (not shown) are input. Then, this torque distribution controller 27 operates the front wheel brake device 17.18 or the rear wheel brake device 19.20 to reduce the driving torque of the front wheels 2, 3 or the rear wheels 4, 5 by the amount of braking torque. By controlling the engine output to compensate for this reduction in drive torque, the front wheels 2
The torque distribution is variably controlled while maintaining the total driving force of the rear wheels 4.5 and 4.5 degrees.

Next, referring to FIG. 3, the configuration of the braking pressure control valve and its actuator for operating each of the brake devices 17 to 20 by the brake controller 21 will be explained.
Brake device for front wheels from mask cylinder 30 1.7.1
First and second brake pressure control valves 33.34 are installed on the first and second brake pressure passages 31.32, respectively, which supply brake pressure to the brake system 8 and the rear wheel brake device 1f19, 20, respectively. Also provided are actuators 35, 36 that actuate these control valves 33, 34, respectively.

Both of the brake pressure control valves 33 and 34 are connected to the cylinder 3.
Insert pistons 33b and 34b into 3a and 34a,
The inside of these cylinders 33a, 34a is a variable volume chamber 33e.
, 34e and control room 33d.

34d, and the pistons 33b, 34b.
A variable volume chamber 33c by springs 33e and 34e,
The structure is such that it is biased in a direction in which the volume of 34c increases. Then, the first brake pressure passage 31 from the mask cylinder 30 described in -1 to the front wheel brake device 17.18 and the second brake pressure passage 32 to the rear wheel brake device 1-9.20 have the above-mentioned volume. The braking pressure normally generated by the mask cylinder 30 is supplied to the brake devices 17 to 20 through the variable volume chambers 33e and 34e, respectively. There is.

In addition, the control chamber 33 has screws 1 to 33b and 34b.
By the control pressure introduced into d and 34d, the
Check valves 33f, 34f that close the braking pressure inlets to the variable volume chambers 33c, 34c when the variable volume chambers 33c, 34c move in a direction in which the volumes of the variable volume chambers 33c, 34c decrease against the springs 33e, 34C. is provided.

Then, control pressure is introduced into the control chambers 33d and 34d, and the check valves 33f and 34f operate the first and second check valves.
When the braking pressure passages 31, 32 are blocked, the variable volume chambers 33c, 3 are moved by the movement of the pistons 331], 34b.
Braking pressure is generated within 4e, and this braking pressure is applied to the front wheel brake device 17.18 or the rear wheel brake device 19.20.
Supplied to J: sea urchin.

On the other hand, actuators 35 and 36 that operate these braking pressure control valves 33 and 34 are actuated by pressure increasing solenoid valves 3 and 36, respectively.
5a, 36a, and pressure reducing solenoid valves 35b, 36b. and the pressure increasing solenoid valves 35a, 36;
i is from the oil pump 37 via the relief valve 38 -
1-Control chamber 33d, 34d of fertilizer dynamic pressure control valve 33.34
The pressure reducing solenoid valves 35b and 36b are arranged in the control pressure supply lines 39 and 401 leading to the control chamber 3, respectively.
They are placed on drain lines 41 and 42 led from 3d and 34d, respectively. These solenoid valves 35a, 36a, 35b, 36b are controlled to open and close by the brake 17-key control signal from the brake controller 21, so that the pressure increasing solenoid valves 35a, 36a are opened and the pressure reducing solenoid valves 35b, 36b are not connected. When the brake pressure control valve 33
．． By introducing control pressure into the control chambers 33d and 34d of 34, braking pressure is supplied to the front wheel brake device 17, 18 or the rear wheel brake device [19, 20, and the pressure increasing solenoid valve 35a , 36a are closed and the pressure reducing solenoid valve 35
1) When the control rooms 33d and 34b are opened, the control rooms 33d and 34
By discharging the control pressure from d, the braking pressure supplied to the brake devices 1, 7, 18 or 20 is reduced, and in this way, each brake device 17 to
By adjusting the braking pressure supplied to the wheel 20, the braking torque applied to the front wheels 2, 3 or the rear wheels 4.5 is controlled.

Next, the operation of this embodiment will be explained with reference to the flowchart of FIG. 4 showing the torque distribution control operation by the torque distribution controller 27.

First, step S8. According to S2, each sensor 26, 28 shown in FIG.
．． Based on the signals from 29, each momentum such as accelerator opening, steering angle, and vehicle speed is measured, and then in step S, depending on whether the steering angle is greater than a set value, the vehicle is in a straight-ahead state or in a turning state. Determine if there is. If the vehicle is traveling straight ahead, in step S4, the acceleration a (= V
After determining NVN-1>, the basic torque distribution ratio Rr of the rear wheels 4 and 5 is determined in accordance with this acceleration G in step S5. The fifth
It is preset/determined based on the map as shown in the figure. This map shows that the basic torque distribution ratio Rr is
g is set to increase.

Next, in step S6, the acceleration G is set to a second set value G2.
Determine whether it is -L or not. Then, when GAG2,
That is, during relatively slow acceleration, which seems to be during non-acceleration, the above basic l/rque distribution ratio R, rg is set as the 11 standard torque distribution ratio Flr on the rear wheel side in step S7, and G≧
02, that is, at a relatively rapid acceleration, step S8
Then, the correction amount ΔRr of the rear wheel torque distribution ratio is set based on the map in FIG. 6, and the basic torque distribution ratio F? ,
The target torque distribution ratio Rr for the rear wheels is set by subtracting this correction amount ΔR,r from 1-r. Here, in the Mazda shown in FIG. 6, the subtraction correction plate ΔRr of the rear wheel side torque distribution ratio is set to a larger value as the vehicle speed (2) increases in a high vehicle speed region of the set vehicle speed 71 or higher.

Then, the torque distribution ratio on the rear wheel side is the same as the target torque distribution ratio R1 set in step S9).
In step S, 1-herk distribution control of 0 or less is performed so that -.

In other words, in step Sho, the output torque according to the accelerator opening degree, that is, the front wheel 2°3 and rear wheel 4 requested by the driver.
．． 5.1・-Tal required torque T. In addition, in step S++, this request I and rkT are calculated.

Torque Ti < = 2 Rr-T required to achieve the above target 1-luke distribution ratio R, r while satisfying
.

), and in step S12, it is determined whether this required torque T1 is smaller than the maximum torque MAX that can be output in the current state. And T I<
At T MAX, step SI3. In S1.4, the braking of l-tal for the left and right front wheels 2.3 is 1-luk Bf.
and output torque T are set as follows.

Bf = (2Rr 1)・T.

T='l''+ (=2 ・Rr ・To) Then, in order to obtain this braking 1 herk Bf, a 1 no-gi control signal is output to the γ actuator 35 shown in FIG. The pressure control valve 33 supplies υJ dynamic pressure to the front wheel brake equipment Fi7, 18, and the above output '
The actuator 24 shown in FIG.
An engine control signal is output to the engine 6 to control the opening degree of the throat valve 23 in the engine 6.

As a result, the driving j~lux Tf and Tr of the front wheels 2.3 and rear wheels 4 and 5 are respectively '1''f=T/2-Bf (1-Rr) ・TgTr=T'/2Rl-・T.

i7. The torque distribution ratio of the rear wheels (Tf:Tr) is set to the target distribution ratio [(1-Rr): Rr], and the total drive torque of the front and rear wheels (Tf-1-Tr
) is the required torque T. 9 In that case, the rear wheel 4.5 ([tll's 1 - basic torque distribution ratio Rr+ which is the base of the torque distribution ratio Rr] has a large acceleration G as shown in FIG. 2Basically, it is set to a larger value as the acceleration increases.4,5
In response to the load shift to the side, the rear wheel 4 degrees 5 side is greatly 1-I
・You will be able to get a good share of your income. Therefore, front wheels 2 and 3
and the drive torque of rear wheels 4 and 5 corresponds to each load1
The driving force of these wheels can be effectively used as the propulsion force of the vehicle without causing slippage.

- On the other hand, when the acceleration G is relatively rapid acceleration equal to or higher than the second set value G2 -L, and when the vehicle speed V is at a high vehicle speed equal to or higher than the set vehicle speed 74, the target 1-lux distribution ratio Rr of the rear wheels is set. However, as shown in FIG. 6, it is a value corrected by subtracting the correction amount ΔRr, which increases as the vehicle speed V increases, from the basic I/Lux distribution ratio Rro, which corresponds to the acceleration of two feet. As the vehicle speed increases, the l/lux distribution is corrected from a large distribution on the rear wheel side to a direction that equalizes the distribution on the front and rear wheels, to a direction that increases the distribution on the front wheel side. Become. As a result, at high vehicle speeds, the steering characteristics are corrected from an oversteer tendency to neutral steer and understeer, and the driving force of the rear wheels 4 and 5 is suppressed. This will prevent the slip limit from decreasing with respect to lateral forces, and therefore the stability of the vehicle at high vehicle speeds will be improved.

Note that if it is determined in step S12 in FIG. 4 that T, ≧T MAX , that is, by applying braking torque to the front wheels 2.3, the target torque distribution ratio [ ( 1-R r ):Rr], if the 1-ruk T required to obtain =i exceeds the maximum torque TMAX that can be output, step S +s. S
16, the throttle valve 23 of the engine 6 is controlled so that the output torque becomes the maximum output torque of 1~rMAX, and the front wheel 2 is also controlled.

The braking torque Bf applied to 3 is B f = ( TMAX To )
Outputs the B1/K control signal so that the signal becomes /2. In other words, a distribution ratio close to the target distribution ratio is obtained in the range of torque capable of output Ef.

Furthermore, if it is determined in step S3 that the steering angle is greater than or equal to the set value, torque distribution control during turning is performed in step S17.
, the torque distribution ratio on the 5 side is increased to improve turning performance,
At the end of a turn, the 1-lux distribution ratio to the front wheels is increased to improve stability.

(Effects of the Invention) As described above, according to the 1-luke distribution control device for a four-wheel drive vehicle according to the present invention, when accelerating, the
By changing the torque distribution ratio of the wheels, the driving force of the front and rear wheels is adjusted to correspond to the respective loads, and the driving force is matched with the propulsion force of the vehicle without causing any slip on either the front or rear wheels. 1
In addition to correcting the torque distribution according to the above-mentioned acceleration according to the vehicle speed, it is possible to achieve a torque distribution that takes into consideration steering characteristics and straight-line stability of the vehicle at high vehicle speeds. It happens every time I get it. This improves vehicle stability at high speeds while ensuring good acceleration performance.

[Brief explanation of the drawing]

FIG. 1 is an overall schematic configuration diagram of the present invention, and FIG.
The figures show an embodiment of the present invention; Fig. 2 is a control system diagram, Fig. 3 is a circuit diagram showing the configuration and arrangement of the brake pressure control valve and its actuator, and Fig. 4 shows one-herc distribution control. Flowchart IA, FIGS. 5 and 6 are explanatory diagrams of each map used in this control. 2.3...Front wheel, 4,5...Rear wheel, 21.25...
- Torque distribution changing means (brake controller L-roller, engine controller L-roller), 27...) - Luk distribution control means, l-Lux distribution correcting means (torque distribution controller 1-roller), 29... Vehicle speed Detection means (vehicle speed sensor). Figure Figure

Claims (1)

[Claims] (1) A torque distribution control device for a four-wheel drive vehicle, which is configured to drive front wheels and rear wheels by engine output, and is provided with a torque distribution changing means for changing torque distribution between the front and rear wheels, an acceleration detection means for detecting the acceleration of the vehicle; a torque distribution control means for operating the torque distribution changing means to change the torque distribution between the front and rear wheels according to the acceleration detected by the detection means; A four-wheel drive vehicle comprising: a vehicle speed detection means for detecting speed; and a torque distribution correction means for correcting torque distribution according to the acceleration according to the vehicle speed detected by the detection means. Torque distribution control device.