JP2001277883A - Power distribution control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power distribution control device excellent both in quick response performance and convergence performance. SOLUTION: This graph shows a throttle valve opening (m), a torque distribution ratio (r) to a driven wheel, and time-based change of a differential rotation number ΔN between a main drive wheel and the driven wheel when controlled so that a residual time T (correcting time for a slipping state or the like) is long in the condition of dΔN/dt<=0. Degree of need for stable traction by four- wheel drive is quantitatively determined based on the throttle valve opening (m) etc. When the differential rotation number ΔN is being converged to 0 (at the time of dΔN<=0), time constant τ (∝T) is determined based on a monotone increasing function f1 (m) in accordance with this degree of need. For example, in PID control to a coil current I of an electromagnetic clutch, a coefficient (gain G) of a current deviation ΔI is set to be roughly in inverse proportion to the time constant τ, so the torque distribution ratio (r) once reaching a preferable value r0 is stably converged, and at this time, the torque distribution ratio (r) is maintained within a proper range (in a width of δ) for a necessary time (residual time T).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power distribution control device for distributing the power of a vehicle to a plurality of drivable wheels, and more particularly, to a torque distribution ratio to driven wheels in a four-wheel drive vehicle having an on-demand 4WD mechanism. Regarding the means for determining. However, the "driven wheels" referred to here are drivable wheels that can temporarily set the torque distribution ratio of the vehicle power (driving force) supplied from the engine or the motor to 0 or a relatively small value. The "main driving wheel" here is a drivable wheel to which relatively large power (driving force) is constantly transmitted during traveling or acceleration.

[0002]

2. Description of the Related Art As an apparatus for controlling a torque distribution ratio for each drivable wheel by electronic control, for example, Japanese Patent Laid-Open Publication No. Hei 7-40753: "Comprehensive control system for driving force distribution between left and right wheels and front and rear wheels" , "Prior art 1".)
Described in Japanese Patent Laid-Open Publication No. Hei 7-2
5258: Differential limit control device ”(hereinafter,“ prior art 2 ”)
Say And the like are generally known.

In these prior arts, in a four-wheel drive vehicle of a so-called on-demand 4WD mechanism in which the torque distribution ratio between the front wheels and the rear wheels is variable, for example, the torque distribution ratio r to the driven wheels is "0≤r ≦ r _max <1 (r _max is a predetermined constant) ”, the differential rotation speed ΔN between the front wheels and the rear wheels is monitored, and as the differential rotation speed ΔN increases, It is a general control theory to increase the torque distribution ratio r to the driving wheels. That is, the torque distribution ratio r to the driven wheels is controlled so as to be substantially proportional to the differential rotation speed ΔN between the front wheels and the rear wheels until reaching a certain saturation point (upper limit: r _max ). This is a general control method.

[0004] As a clutch mechanism of a coupling device, a large number of clutch mechanisms utilizing an electromagnetic clutch having higher responsiveness than a hydraulic clutch are currently being used. FIG.
((a), (b)) is a block diagram illustrating a logical configuration of a conventional power distribution control device. For example, the calculation of the torque distribution ratio r as described above is specifically executed by the “torque distribution ratio calculation unit 202” in FIG. However, FIG.
The definition of each variable in is as follows.

(Definition of Variables) n: Generic term of rotational speeds (n1, n2,...) Of each drivable wheel ΔN: Differential rotational speed between front wheel and rear wheel r: Torque distribution ratio to driven wheel I _n: coil current command value V _n: the coil voltage command value V _cc: supply voltage lambda: the duty ratio in chopper control (PWM control)

Further, some of these prior art, for example as shown in FIG. 13 (b), actually measuring the coil current of the electromagnetic clutch, the command value I _n of the measured values I _a and the coil current
Some control the coil current I more accurately by PID control based on the current deviation ΔI (≡I _n −I _a ) (proportional-integral-derivative control performed by “PID 210” in the figure).

In the proportional-integral-differential control executed by "PID 210" in FIG. 13B, for example, the following equation (1) is used.
A method such as determining the value of the coil voltage command value V _n have been taken on the basis of.

V _n = λ′V _CC + g ₁ ΔI + g ₂ ∫ΔIdt + g ₃ dΔI / dt (1)

Λ = V _n / V _CC (2)

Here, λ ′ is a duty ratio (or a tentative initial value of the duty ratio λ) obtained in the previous control cycle and used in the previous PWM control, and the gains g ₁ , g ₂ , g ₃ is an appropriate constant. Also,
Equation (2) is expressed by “duty ratio calculation unit 20” in FIG.
5] is a calculation formula of the duty ratio λ, which is executed by “5”.

[0009]

FIG. 14 is a graph showing a problem of the prior art.
Time-varying changes in the state variables of the torque distribution ratio r to the driven wheels and the differential rotation speed ΔN between the main drive wheels and the driven wheels are illustrated. More specifically, this graph shows the result of simulating the driving state (slip stop state) of a four-wheel drive vehicle at the time of “sudden start on a low friction road”, for example, on a frozen road surface in snowy days. From this graph, it can be seen that the clutch mechanism is chattering.

When the clutch mechanism of the coupling device is constituted by an electromagnetic clutch, the responsiveness (quick response) of the clutch mechanism becomes extremely high. For this reason, in the on-demand 4WD system using the electromagnetic clutch, for example, in the case of starting or accelerating on a low friction road as described above, for example, chattering and a slip stop phenomenon as shown in FIG. is there. If the responsiveness of the clutch mechanism is high, the coupling device may cause chattering even when suddenly starting on a road surface having a relatively high friction coefficient, for example. That is, in these cases, there is a possibility that stable and reliable traction (driving force) cannot be sufficiently obtained, or that the riding comfort is lowered due to abnormal noise or vibration of chattering.

However, if the response of the clutch mechanism (mainly an electromagnetic clutch) is reduced uniformly (overall) as a countermeasure, reliable and stable traction (acceleration performance) by four-wheel drive can be obtained. In an emergency that is immediately required, there is a possibility that sufficiently high responsiveness (rapid response) for traction may not be obtained.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a high response to a required acceleration performance (traction), and a chattering or slip stop phenomenon. It is an object of the present invention to provide a power distribution control device that does not generate the power, that is, a power distribution control device excellent in both quick response and damping (convergence).

[0013]

In order to solve the above-mentioned problems, the following means are effective. That is, the first means is a power distribution control device that controls a “power distribution ratio to driven wheels or a related value” r when distributing the power of the vehicle supplied from the engine or the motor to the plurality of drivable wheels. In the above, there is provided a residual time control means for controlling a residual time T in which r once reaches the preferred value r0 remains within its proper range or in the vicinity of the preferred value r0. If the amount of change dΔN within a predetermined short time dΔN is “dΔN ≦ 0” in accordance with the increase / decrease state of the differential rotation speed ΔN, which is the difference between the number of rotations and the rotation speed of the driven wheel, the remaining time T The value of the proportional time constant τ is a function f1 in which the acceleration operation related value A related to the driver's acceleration operation is an independent variable.
(A).

Here, the acceleration operation-related value A may be a set of parameters composed of a plurality of parameters. The acceleration operation-related value A may be anything as long as it reflects the driver's intention to operate the vehicle regarding acceleration, and may be, for example, an accelerator pedal depression amount, an engine speed, or the like. Acceleration operation related value A of the present invention
Can be composed of variables (acceleration operation parameters) that can take at least two values.

Incidentally, for example, the above f1 used in the present invention
Each function such as is generally performed by a known information processing technique, for example, by a predetermined data map (table), a polynomial, or an arbitrary means such as a predetermined algorithm.
It can be specifically configured. That is, all functions used in the present invention are one-to-one from real numbers to real numbers (more specifically, rational numbers to rational numbers), or
Any structure may be used as long as it is configured by a mapping that has many-to-one correspondence, and the specific realization method is not limited.

The second means is a gain G in the proportional control, the proportional integral control, or the proportional integral derivative control of the “hydraulic pressure, coil current, or related value thereof” I of the coupling device that realizes the power distribution ratio. In the residual time control means of the first means, the coefficient of at least one of the deviation of I, the integral of the deviation, and the differentiation of the deviation (the gain G) Is substantially monotonically decreased or substantially inversely proportional to the time constant τ, so that the above-mentioned residual time T is substantially proportional to the time constant τ.

In the third means, as the compensation processing of r, the residual time control means of the first or second means may set a lower limit value of a fluctuation amount Δr per unit time of r as a time constant. By controlling based on τ, the remaining time T is made substantially proportional to the time constant τ.

Further, the fourth means includes the first to third means.
In any one of the means, the accelerator operation depression value θ, the engine speed p, the throttle valve opening m, or these related values are adopted as the acceleration operation related value A, and “A1” is used as the function f1. <A2⇒f1
(A1) ≦ f1 (A2) ”.

Further, the fifth means is characterized in that the above-mentioned first to fourth means
If the change amount dΔN is “dΔN> 0” in any one of the remaining time control means, a monotonous decreasing function in which the value of the time constant τ is the change amount dΔN or its related value as an independent variable B f2 (B).

Here, B may be a set of parameters composed of a plurality of parameters. Further, the function f2 is expressed as “B1 <B2⇒f2 (B1) ≧ f2 (B
2) "is a monotonically decreasing function in a broad sense, and therefore may be a constant function whose function value is particularly constant. With the above means, the above-mentioned problem can be solved.

[0021]

Function and Effect of the Invention "Residual time T" in the present invention
Is the time required to reestablish the state of the vehicle when the vehicle enters the slip stop state. During this period, it is desirable that as much driving performance as possible is provided by all the drivable wheels as much as possible. Conversely, at least until these slip states are reestablished (for example, from a slip stop state to a transition to a stable start state with a certain driving force), the torque distribution to the driven wheels is It is desirable that the torque distribution ratio r be maintained at a value near the suitable value r0.

FIG. 1 is an enlarged graph of a part of FIG. 14, and shows the change in the torque distribution ratio r to the driven wheels and the differential rotation speed ΔN between the main drive wheels and the driven wheels with respect to time t. . As can be seen from FIG. 1, in the driving state of the four-wheel drive vehicle at the time of the “rapid start on low friction road”, “r0−δ <
It is considered that the range of “r ≦ r0” is an appropriate range of the torque distribution ratio r. If the torque distribution ratio r is larger than necessary, the fuel consumption is not suppressed accordingly, and if the torque distribution ratio r is smaller than the required amount, the differential rotation speed ΔN increases and a slip phenomenon occurs.

Therefore, for example, under the conditions shown in FIGS. 1 and 14, "r0-δ <r" or "r0-δ <r≤r
If the time “0” is sufficiently ensured, that is, if the above “residual time T” is sufficiently ensured, the chattering and the slip stop phenomenon can be avoided. The residual time control means of the present invention controls the “remaining time T” using one parameter (time constant τ).
The remaining time T is controlled so as to be substantially proportional to one time constant τ.

When the differential rotation speed ΔN is converging to 0 (when dΔN ≦ 0), the remaining time T is maintained in order to maintain the convergence (attenuation) and avoid the occurrence of chattering or the like. The longer the time when stable traction by four-wheel drive is required, the better. The necessity (degree of necessity) of this stable traction can be quantitatively read from the acceleration operation related value A described above. For example, the differential rotation speed ΔN
Is larger and the accelerator pedal depression amount θ (or the throttle valve opening m or the like) is larger, it is determined that the slip state is more severe and stable traction by four-wheel drive is required. Good.

FIG. 2 shows that “dΔN ≦
0, the throttle valve opening m, the torque distribution ratio r to the driven wheels, and the differential rotational speed ΔN between the main drive wheels and the driven wheels when the “remaining time T” is increased. It is a graph which shows the time-dependent change of each state variable. According to the above-described means of the present invention, the “necessity of stable traction” is quantitatively measured from the acceleration operation-related value A such as the throttle valve opening m, and the differential rotation speed ΔN converges to zero. In some cases (dΔN ≦ 0), the value of the time constant τ is determined by the function f1 according to the necessity of the traction. By such optimization control of the residual time T using the time constant τ as an adjustment parameter, the above-described residual time T required for each state is appropriately secured. Accordingly, until the slip state is reestablished, the torque distribution ratio r is maintained within the appropriate range (“r0−δ <r” or “r0−δ”).
<R ≦ r0 ”).

The second means of the present invention determines the time constant τ to a suitable value as described above after securing the responsiveness when controlling the torque distribution ratio r, and then determines the τ. By adjusting a coefficient (gain G) such as a current deviation of a coil current of a PID-controlled electromagnetic clutch in accordance with the value of, the stability (convergence) of the torque distribution ratio r once reaching a suitable value is secured. Is what you do.

The above-mentioned third means of the present invention is characterized in that, when controlling the torque distribution ratio r, the quick response is ensured.
After the time constant τ is determined to be a suitable value as described above, the amount of fluctuation of the torque distribution ratio r is then limited according to the value of τ, thereby stabilizing the torque distribution ratio r that has once reached the suitable value. (Convergence).

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on specific embodiments. However, the present invention is not limited to the embodiments described below. (First Embodiment) FIG. 3 is a schematic system configuration diagram of a power distribution control device 100 according to the present embodiment, which is mounted on a four-wheel drive vehicle. The four-wheel drive vehicle has an FF-based so-called on-demand 4WD mechanism, which suitably controls the torque distribution ratio between the front wheels and the rear wheels.

The transaxle 40 is provided with a transmission and a transfer integrally, and the driving force (torque) supplied from the engine 30 has a gear ratio selected by the transaxle 40.
It is output to a differential gear (differential device) 25. Thereafter, the torque transmitted to the front differential gear (differential device) 25 is applied to the front wheel axles 27, 2
7 and the propeller shaft 20, and the main drive wheels (front wheels) 1 and 2 are driven. A coupling (clutch mechanism) 5 is provided at one end on the rear side of the propeller shaft 20.
0 is connected.

The torque transmitted to the coupling 50 via the propeller shaft 20 is sequentially transmitted to the rear wheel drive shaft 24, the rear differential gear 26, and the rear wheel axle 28, and the driven wheel (rear wheel) Drive 3 and 4. However, when the torque distribution ratio r to the driven wheels (3, 4) is 0, the clutch mechanism of the coupling 50 is controlled to the disengaged state (non-coupled state). , 4 are not driven. Generally, the clutch mechanism of the coupling 50 may be a mechanism by electromagnetic operation (electromagnetic clutch) or a mechanism by hydraulic pressure (hydraulic clutch) as in the related art.

However, in the first embodiment, the clutch mechanism of the coupling 50 is constituted by an electromagnetic clutch. With this clutch mechanism, the torque distribution ratio r to the driven wheels (3, 4) is within a predetermined range (0 ≦ r
≦ r _max <1). The maximum value r _max of the torque distribution ratio r may be about 1/2. For example, “0 ≦ r ≦ 1 /
If "2", the clutch mechanism is directly connected when "r = 1/2 (= r _max )", and at this time substantially the same torque is distributed to the front wheels and the rear wheels. The operation of the electromagnetic clutch is based on the current I flowing through the coil C in FIG.
(Or, it is controlled by the current I _{n in} FIG. 5). That is, according to the target value of the torque distribution ratio r, the current I
The target value (command current) I _n are determined.

The wheel speed signals n1, n2, n3, and n4 respectively output from the rotation sensors 5 to 8 (hereinafter, may be collectively referred to as "driving wheel rotational speed n" or simply "n"). Is the rotational speed of each of the drivable wheels 1, 2, 3, and 4 [rp
m]. The throttle valve opening sensor 10 outputs a value of the throttle valve opening m. These output data are shown in FIG.
Is input to the power distribution control device 100.

FIG. 4 is a hardware configuration diagram of the power distribution control device 100 according to the first embodiment. Coil C for operating electromagnetic clutch constituting coupling 50
Receive power from a DC drive power supply (power supply voltage V _CC ). The magnitude I of this DC current is determined by the power MOS F
An electronic control switch SW constituted by ET and a PMO
It is controlled by chopper control using the S drive circuit 108 and the PWM converter 105. CPU 101 is a ROM
By using a program described later stored in the RAM 102 and the RAM 103 and the above numerical values (m, n, V _CC , i), etc.,
A duty ratio λ to be output to the PWM converter 105 is calculated.

On the lower voltage side (0 ground side) of the electronic control switch SW, a resistor 110 having a resistance value r [Ω] is connected in series with the coil current path (that is, on the coil current path).
It is connected. The negative terminal of the current detector 109 is connected to the lower voltage side of the resistor 110, and the current detector 1 is connected to the upper voltage side.
09 are connected to each other. The current detector 109 detects a current i flowing through the resistor 110 by inputting a potential difference v [V] between both ends of the resistor 110, and
Output to the / D converter 106. The CPU 101 calculates the value of the coil current I [A] (measured coil current value I _a ) from the current i input from the A / D converter 106. As a calculation method, for example, there is a method of averaging several values measured within a predetermined cycle of the current i.

FIG. 5 is a block diagram showing a logical configuration of the power distribution control device 100 according to the first embodiment.
This configuration is different from the conventional configuration shown in FIG.
The remaining time control unit 300 is added. The remaining time controller 300 includes a time constant calculator 301 for calculating the time constant τ, and a gain compensator 302 for calculating a gain G in the PID control based on the time constant τ.

The operation of each block in FIG. 5 will be described below with reference to FIG. FIG. 6 is a flowchart of a program executed by the CPU 101 (FIG. 4) of the power distribution control device 100 according to the first embodiment. In this program, first, at step 605, the current i, the throttle valve opening m, and the rotation speed n (n1,
n2, n3, n4) and the power supply voltage _Vcc . However, since the power supply voltage _Vcc is a physical quantity whose change with time is relatively small, it is not always necessary to input the power supply voltage _Vcc every control cycle.

Next, in step 610 (differential rotational speed calculation unit 201), the differential rotational speed ΔN between the front wheels and the rear wheels is obtained by the following equation (3).

ΔN = c1 (n1 + n2-n3-n4) / 2 (3) where c1 is an appropriate proportional constant. However, when the inputs n1, n2, n3, and n4 from the rotation sensors (5 to 8) match the rotation speeds of the respective drivable wheels, c
1 = 1 may be set.

Next, at step 615 (torque distribution ratio calculation section 202), a torque distribution ratio r (0 ≦ r ≦ r _max ) to the driven wheels is determined from the above-mentioned differential rotation speed ΔN. Here, the value of the upper limit value r _max of r is set to, for example, 意味, which means the direct connection state of the coupling device 50. Further, the value of r is determined so as to be substantially proportional to ΔN as in the known prior art.

The following steps 620 to 6
The remaining time control unit 300
Is specifically realized. That is, in step 620, an increment dΔN of the differential rotation speed ΔN obtained in step 615 from the previous control cycle is obtained. If this value is 0 or less, the process proceeds to step 625, and if this value is positive, the process proceeds to step 630. Move.

In step 625, the value of the time constant τ is determined by the monotone increasing function f1 shown in FIG. Thus, even if the differential rotation speed ΔN tends to decrease (or not change), the larger the value of the throttle valve opening m, that is, the stronger the driver's intention to accelerate, the more the four-wheel drive , The time during which stable traction is maintained, that is, the "remaining time T" becomes longer.

In step 630, the value of the time constant τ is determined by the monotone decreasing function f2 shown in FIG. Accordingly, the time constant τ is set to be smaller when the increment dΔN is large, that is, when the slip state is rapidly deteriorating or intensifying, such as in an emergency where stable traction is required by four-wheel drive. In addition, high responsiveness in driving performance can be obtained. Steps 620 to 630 described above
Constitutes the time constant calculation unit 301.

Step 650 (gain compensator 30)
In 2), the function g shown in FIG.
Obtains the gain G by (equation (4)), thereby compensating for the coefficients g ₁ of the proportional term ΔI of the formula (1). That is, in the first embodiment, in the processing described later, P is calculated using the following equation (5) based on the gain compensation instead of the equation (1).
Perform ID control.

[0043]

G = g (τ) (4)

V _n = λ′V _CC + GΔI + g ₂ ∫ΔIdt + g ₃ dΔI / dt (5)

Step 660 (Coil current calculator 20)
In 3), step 615 (the torque distribution ratio calculating section 20)
From the torque distribution ratio r obtained in 2), the coil current command value I
Determine _n . In step 670, the coil current measurement value _Ia is calculated from the average value of the current i of FIG. 4 measured a predetermined number of times in the current control cycle.

In step 680 (PID control section 210), using the current deviation ΔI (≡I _n −I _a ) and the gain G of equation (4), the coil voltage command value V is calculated as shown in equation (5).
_{Find n} . However, by substantially the same means, and the gain g ₂ of the integral term, or compensation for the gain g ₃ of the differential term simultaneously, or may be performed alone. Instead of the function g, the dependent variable (function value G) decreases exponentially with respect to the independent variable (time constant τ), for example, as in a function h shown in FIG. It is also possible to use a monotonically decreasing function that is inversely proportional.

Further, in step 690 (duty ratio calculation unit 205), the duty ratio λ is calculated by the equation (2), and in step 695, this duty ratio λ is output to the PWM control unit 206 in FIGS. .

The monotonically decreasing functions such as the functions g and h described above may be empirically selected according to the characteristics of the coil C and the coupling device 50 shown in FIG. For example, such a gain compensation unit 302 (step 650)
By virtue of the action (1), a sharp decrease in the torque distribution ratio r can be suppressed. That is, these gain compensation controls allow the above-mentioned residual time T to be maintained appropriately, for example, as shown in FIG.

(Second Embodiment) FIG. 10 is a hardware configuration diagram of a power distribution control device 400 according to the second embodiment. The power distribution control device 400 can be mounted on the 4WD system of FIG. 3 instead of the power distribution control device 100 (FIG. 4) of the first embodiment. Main power distribution control device 4
00 and the power distribution control device 100 described above,
The only difference is the presence or absence of the D converter 106 and the current detector 109. That is, the power distribution control device 400 does not have a feedback loop of the coil current I.

FIG. 11 is a block diagram showing a logical configuration of a power distribution control device 400 according to the second embodiment. This configuration is an improvement of the conventional logical configuration of FIG. 13A, and a residual time control unit based on the means of the present invention is provided between a torque distribution ratio calculation unit 202 and a coil current calculation unit 203. The point where 500 is provided is the most significant feature.

The remaining time control unit 500 includes a time constant calculating unit 501 for calculating a time constant τ, and a lower limit of a variation Δr per unit time s of the torque distribution ratio r to the driven wheels based on the time constant τ. And a torque fluctuation limiter 502 for controlling the value kD (k = ± 1).

The operation of each block in FIG. 11 will be described below with reference to FIG. FIG. 12 is a flowchart of a program executed by CPU 101 (FIG. 10) of power distribution control device 400 in the second embodiment. In this program, first, at step 805, the throttle valve opening m and the rotation speed n (n
1, n2, n3, n4) and the power supply voltage _Vcc . However, since the power supply voltage _Vcc is a physical quantity whose change with time is relatively small, it is not always necessary to input the power supply voltage _Vcc every control cycle.

Steps 610 to 625 operate in the same manner as in the first embodiment. That is, for example, in step 620, the increment dΔN of the differential rotation speed ΔN obtained in step 615 from the previous control cycle
If this value is 0 or less, the process proceeds to step 625, and if this value is positive, the process proceeds to step 830. The second
The remaining time control unit 500 according to the embodiment performs step 62.
0, step 625, and steps 826 to 8
It consists of up to 55 steps.

In step 826, -1 is substituted for a variable k representing a sign. On the other hand, in step 830, as shown by the broken line in FIG. 8, the value of the time constant τ is determined to be a predetermined appropriate constant τ ₀ irrespective of the fluctuation amount of the differential rotation speed ΔN. In step 835, +1 is substituted for a variable k representing a sign. Steps 620, 625, and 8 described above
Through the processing from 26 to 835, the processing of the time constant calculation unit 501 is executed.

The operation of the torque fluctuation limiter 502 for controlling the lower limit value kD of the fluctuation amount Δr will be described below. The torque variation limiting unit 502 determines in step 840 to step 8
It consists of up to 55 steps. Step 8
At 40, the torque distribution ratio r to the driven wheels is given by the following equation (6).
Is determined. Here, r is the value obtained in step 615 (torque distribution ratio calculation unit 202) this time, and r ′ is the value output from the last remaining time control unit 500 to the coil current calculation unit 203 (in the previous control cycle). This is the command value of the determined torque distribution ratio.

Δr = r−r ′ (6)

Next, at step 845, the absolute value D of the lower limit value of the variation Δr of the torque distribution ratio r is obtained by the following equation (7). Here, δ (> 0) is the width of the appropriate range of the torque distribution ratio r under the present situation as shown in FIGS. 1 and 2, for example, and s (> 0) is the length of each control cycle described above. , Τ
(> 0) is the time constant obtained by the current time constant calculation unit 501 (step 625 or step 830). However,
Appropriate constants may be used for δ and s.

D = δs / τ (7)

In step 850, a substitution calculation process for resetting the value of the variation Δr of the torque distribution ratio r is performed by the following equation (8).

Δr = MAX (Δr, kD) (8) where MAX (a, b) is a function for selecting the smaller one from a and b.

In step 855, a substitution calculation process for resetting the command value r 'of the torque distribution ratio output to the coil current calculation unit 203 this time is executed according to the following equation (9).

R ′ = r ′ + Δr (9) where r ′ on the left side is the current command value to be updated, and r ′ on the right side is the command value used in the previous control cycle. .

Step 860 (Coil current calculator 20)
In 3), the coil current I (FIG. 1) to be passed through the coil C is obtained from the torque distribution ratio command value r 'obtained in step 855.
Determining the command value I _n of 0). In step 880 (coil voltage calculation unit 204), than the command value I _n of the coil current determined in step 860, it determines a command value V _n of the coil voltage.

Further, in step 690 (duty ratio calculation unit 205), the duty ratio λ is calculated by the equation (2), and in step 695, this duty ratio λ is calculated as shown in FIG.
0, output to the PWM control unit 206 in FIG.

According to such a method, it is possible to realize a torque distribution ratio in which a high speed response and a stable damping property (convergence) are guaranteed. And an excellent power distribution control device which is high in cost and free from chattering and slip stop phenomenon can be obtained.

The acceleration operation-related value (A) of the present invention relating to the driver's acceleration operation may be any value as long as it reflects the driver's intention to operate the vehicle for acceleration. For example, the accelerator pedal is depressed. It may be an amount or an engine speed. The acceleration operation related value (A) of the present invention is at least 2
It can be composed of variables that can take values greater than or equal to the value.

Further, for example, the related value such as the throttle valve opening m may be the number of rotations of a gear or a shaft of a transmission system for transmitting the engine output to the drivable wheels. It is also possible to detect the driver's intention to accelerate the vehicle from these numerical values or the amount of change thereof.

In each of the above embodiments, the resistance 1
10 or a switch SW (power MOS).
Since it is assumed that the resistance value γ when the FET (FET) is conducting is sufficiently small, the duty ratio λ is obtained by equation (2). If the magnitudes of r and γ cannot be ignored, It is assumed that the duty ratio λ is obtained from Expression (10).

Λ = V _n / {V _cc −I (r + γ)} (10) where I is the coil current described in FIG. 4 or FIG. 10, and this value is the command value of the coil current. shall be used to measure I _a of I _n or the coil current.

The above functions such as f1, f2 and g are as follows:
By a generally known information processing technique, a specific configuration can be made using an arbitrary method such as a predetermined data map (table), a polynomial, or an algorithm.

[Brief description of the drawings]

FIG. 1 is a graph illustrating a change in a torque distribution ratio r to a driven wheel and a differential rotation speed ΔN between a main driving wheel and a driven wheel with respect to time t, for explaining an operation of the present invention.

FIG. 2 is a graph for explaining the effect of the present invention, showing changes with respect to time t of a throttle valve opening m, a torque distribution ratio r to a driven wheel, and a differential rotation speed ΔN between a main driving wheel and a driven wheel.

FIG. 3 is a system configuration diagram of a vehicle equipped with a power distribution control device 100 according to the present invention.

FIG. 4 is a hardware configuration diagram of a power distribution control device 100 according to the first embodiment.

FIG. 5 is a block diagram showing a logical configuration of a power distribution control device 100 according to the first embodiment.

FIG. 6 is a flowchart of a program executed by a CPU 101 of the power distribution control device 100 according to the first embodiment.

FIG. 7 is a graph showing the relationship between the time constant τ and the throttle valve opening m (monotonically increasing function f1).

FIG. 8 is a graph showing the relationship between the time constant τ and the increment dΔN of the differential rotation speed ΔN (monotonically decreasing function f2).

FIG. 9 shows a relationship between a gain G and a time constant τ (monotonic decrease).
A graph showing.

FIG. 10 shows a power distribution control device 400 according to the second embodiment.
FIG.

FIG. 11 shows a power distribution control device 400 according to the second embodiment.
FIG. 2 is a block diagram showing a logical configuration of FIG.

FIG. 12 is a power distribution control device 400 according to the second embodiment.
9 is a flowchart of a program executed by the CPU 101 of FIG.

FIG. 13 is a block diagram showing a logical configuration of a conventional power distribution control device.

FIG. 14 shows a problem (chattering) of the related art.
Throttle valve opening m, torque distribution ratio r to driven wheels r,
6 is a graph showing a change in a differential rotation speed ΔN between a main drive wheel and a driven wheel with respect to time t.

[Explanation of symbols]

 100, 400 ... power distribution control device 300, 500 ... residual time control unit 301, 501 ... time constant calculation unit 302 ... gain compensation unit 502 ... torque fluctuation limit unit 101 ... CPU (central processing unit) 50 ... coupling (clutch) Mechanism) 10 Throttle valve opening sensor C Coil SW Switch (power MOS-FET) r ... Torque distribution ratio to driven wheels r0 ... Suitable value of r ΔN ... Differential rotation speed between main drive wheel and driven wheel δ: width of the appropriate range of r T: residual time τ: time constant for residual time control I: coil current of electromagnetic clutch G: gain of a control term (proportional term, etc.) for proportionally controlling I A: acceleration operation related value (Θ, p, or m etc.) θ… accelerator pedal depression amount p… engine speed m… throttle valve opening f1… A with A as an independent variable Increasing function f2 ... monotonically decreasing function

Claims (5)

[Claims] 1. A power distribution control device for controlling a “power distribution ratio to driven wheels or its related value” r when distributing power of a vehicle supplied from an engine or a motor to a plurality of drivable wheels. A residual time control means for controlling a residual time T in which the r which has reached the preferred value r0 remains within its proper range or in the vicinity of the preferred value r0, and wherein the residual time control means rotates the main drive wheel. If the variation dΔN of the ΔN within a predetermined short time is “dΔN ≦ 0” depending on the increase / decrease state of the differential rotation speed ΔN which is a difference between the rotation speed of the driven wheel and the rotation speed of the driven wheel, the remaining time A power distribution control device wherein a value of a time constant τ substantially proportional to T is determined by a function f1 (A) having an acceleration operation-related value A related to a driver's acceleration operation as an independent variable. 2. A process of compensating for a gain G in proportional control, proportional integral control, or proportional integral derivative control of “oil pressure, coil current, or their related values” I of a coupling device that implements the power distribution ratio, The residual time control means substantially monotonically decreases or substantially decreases the coefficient (the gain G) of at least one of the deviation of the I, the integral of the deviation, and the derivative of the deviation with respect to the time constant τ. The power distribution control device according to claim 1, wherein the remaining time T is made substantially proportional to the time constant τ by making the time constant τ inversely proportional. 3. As the compensation processing of the r, the remaining time control means controls the lower limit value of the variation Δr per unit time of the r based on the time constant τ, so that the remaining time T The power distribution control device according to claim 1, wherein the power distribution control device is approximately proportional to the time constant τ. 4. The acceleration operation-related value A is an accelerator pedal depression amount θ, an engine speed p, a throttle valve opening m, or a value related thereto. The function f1 is represented by “A1 <A2⇒f1”. (A1) ≦ f1
The power distribution control device according to any one of claims 1 to 3, wherein the power distribution control device is a monotonically increasing function (A2). 5. The method according to claim 1, wherein the remaining time control means is configured to control the change amount d.
When ΔN satisfies “dΔN> 0”, the value of the time constant τ is determined by a monotonically decreasing function f2 (B) using the change amount dΔN or its related value as an independent variable B. The power distribution control device according to any one of claims 1 to 4.