JP3314540B2 - Throttle control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a throttle control device, and more particularly to a device for controlling a throttle (throttle valve) by an accelerator pedal via an actuator (motor).

[0002]

2. Description of the Related Art A conventionally known throttle control device senses an operation amount (operation speed) of an accelerator pedal with a potentiometer or the like, and drives the actuator according to the operation amount to open and close the throttle. This is a so-called throttle-by-wire system that adjusts the engine output.

In such a throttle control device, the relationship between the operation amount of the accelerator pedal and the throttle opening is fixed regardless of the friction coefficient of the road surface. Must use.

A specific conventional example for eliminating such a problem is disclosed in Japanese Patent Application Laid-Open No. 63-109254. In this example, the acceleration of an accelerator pedal operation amount is detected and the acceleration is detected. Is greater than or equal to a predetermined value, the throttle control characteristic is set to the power mode instead of the economy mode.

[0005] With this, even when the economy mode is selected, the throttle opening is set in the power mode at the time of rapid acceleration when the accelerator is suddenly operated, so that the vehicle can sufficiently exhibit acceleration.

Another conventional example is disclosed in Japanese Patent Laid-Open No. 5-113139.
Here, a sub-throttle control constant specified in accordance with the gear position is selected, and a sub-throttle target constant of the sub-throttle is determined based on the sub-throttle control constant, the driven wheel speed and the acceleration thereof. The opening is calculated, and the sub-throttle is controlled by driving the step motor according to the target opening.

As a result, the control is performed at an appropriate throttle opening in accordance with each gear position without being limited to a specific gear position.

[0008]

However, in such a throttle control device, since the traction control that controls the vehicle after slipping is used, the control can be performed only by the driving force acting by the dynamic friction coefficient, and only by the static friction coefficient. There is a problem that it cannot be applied to slopes such as slippery snowy roads that cannot run.

There is also a problem that a special sensor for detecting the wheel speed of the driven wheel is required.

Accordingly, it is an object of the present invention to realize a throttle control device which can reduce the burden on a driver without requiring a special sensor on a slippery snowy road or the like, particularly on a slope.

[0011]

In order to achieve the above object, a throttle control device according to the present invention comprises an accelerator sensor, a driving wheel speed sensor, a shift position sensor, an actuator for driving a throttle, and a throttle. The opening degree sensor and the relationship between the accelerator pedal operation amount and the threshold value of the drive wheel rotational speed acceleration are stored in a look-up table for each shift position, and the current accelerator pedal detected by the accelerator sensor and the shift position sensor, respectively. The threshold value is determined from the look-up table based on the manipulated variable and the shift position, and when the current driving wheel rotational speed acceleration is greater than the threshold value, the actuator is controlled in accordance with the difference, thereby controlling the throttle opening gain. And a nonlinear mapping is obtained based on the accelerator pedal operation amount and the difference. And a, and a controller gradually undo the throttle opening gain the return time when the smaller current drive wheel rotation speed acceleration than the threshold value set the throttle recovery time.

As a method for obtaining the above-mentioned non-linear mapping, fuzzy inference or neural network can be used.

Further, the controller can hold the throttle opening gain and freeze the control when the brake pedal is depressed or the accelerator pedal is not depressed in the process of returning the throttle to the original position.

[0014]

In order to achieve the above object, in the throttle control device according to the present invention, a look-up table built in the controller uses a look-up table as shown in FIG. Is stored for each shift position (gear position).

Then, the controller determines the threshold value of the drive wheel rotational speed acceleration from the look-up table based on the current accelerator pedal operation amount detected by the accelerator sensor and the shift position detected by the shift position sensor.

By comparing this threshold value with the current drive wheel rotational speed acceleration detected by the drive wheel rotational speed sensor, it was found that the drive wheel rotational speed acceleration was larger, that is, the drive wheel was slipping. Sometimes, the difference between the two is obtained. This difference is a value corresponding to the friction coefficient μ of the road surface. By controlling the throttle actuator in accordance with the difference, the throttle opening gain can be changed from the characteristic T1 of the gain 1 to T2 as shown by an arrow A in FIG. And change it to smaller.

However, the above threshold value is exceeded for a moment (about several loops in a control cycle of 16 msec unless the road surface is slippery). Therefore, it is necessary to maintain this effect and control the vehicle until the vehicle speed (ground speed) becomes stable. No.

Based on the accelerator pedal operation amount and the difference, the controller uses the fuzzy inference method (see FIG. 3 (1)) or the neural network method to obtain a non-linear mapping of the throttle based on the accelerator pedal operation amount and the difference. Release time ''
Set as

Here, a method of controlling the throttle opening by the fuzzy inference method will be described with reference to FIG.

First, when the slip of the drive wheel is detected from the rotational speed of the drive wheel detected as described above, the gain is reduced in the direction of arrow A in FIG. 2 to reduce the throttle opening. That is, it is assumed that the controller has returned the accelerator.

Then, the throttle return time t is obtained from the accelerator pedal operation amount s and the difference x between the threshold value and the driving wheel rotational speed acceleration based on the rules of the fuzzy inference method.

Now, considering all combinations of the accelerator pedal operation amount s and the difference x in the fuzzy inference method, the following Table 1 is obtained.

[0023]

[Table 1]

Since there is no negative polarity in both s and x, there are 16 combinations as described above. Here, there are four combinations meaningful when there is an input of s and x as shown in FIG. 4 and enclosed by a thick frame in Table 1, and these are shown by a fuzzy inference method in FIG. (a) to (d), which are expressed as follows. (a) IF (accelerator pedal operation amount s = ZO) and (difference x = PM) THEN (t = PM); (b) IF (accelerator pedal operation amount s = ZO) and (difference x = PB) THEN (t) = PB); (c) IF (accelerator pedal operation amount s = PS) and (difference x = PM) THEN (t = PM); (d) IF (accelerator pedal operation amount s = PS) and (difference x = PB) ) THEN (t = PM).

When these are combined, as shown in FIG. 4, the center of gravity of all overlapping portions becomes the return time t to be obtained.

In this way, the return time t is set to, for example, t3
After that, when the current driving wheel rotational speed acceleration is smaller than the threshold value, as shown by the return time t3, the characteristic is returned (from the characteristic T2 shown in FIG. 2 to the original characteristic T1). However, when a control amount that exceeds the control amount when the throttle opening returns to the original value within the above-mentioned return time t3 occurs, the return time t is newly obtained therefrom.

However, on a frozen uphill road or the like, it is impossible to climb up no matter how well the control is performed once the vehicle runs idle and acts with the dynamic friction coefficient. When the tires spin and the controller recognizes that the road surface is slippery, the state is already observable but not controllable.

Up to this point, the so-called traction control without brake control (no need for a following wheel speed sensor) has been used. However, in the above-described case, the brake pedal is depressed in the process of returning the throttle to the original position, or When the accelerator pedal is not operated, the control value is held and the control is frozen.

When the driver releases the brake pedal and operates the accelerator, and tries to climb the slope again by using the coefficient of static friction, the control is restored to the value at the time of the previous slide to assist the driver in operating the accelerator pedal. It will be.

[0030]

FIG. 5 shows an embodiment of a throttle control device according to the present invention. In this embodiment, reference numeral 1 denotes an accelerator sensor for detecting an accelerator pedal operation amount;
Is a drive wheel rotational speed sensor attached to a drive wheel (output shaft) of the vehicle for detecting the rotational speed thereof, and 3 is a shift position for detecting a shift position (gear position) of a shift lever (not shown). It is a sensor.

Reference numeral 4 denotes a controller (CPU) which receives the output signals of the sensors 1 to 3 and appropriately performs A / D conversion internally and takes in the digital signals as a digital signal. The opening of a throttle (valve) 7 installed in the pipe 6 is controlled. The opening of the throttle 7 is constantly monitored by a throttle opening sensor 8 and fed back to the controller 4 so that a desired throttle opening can be obtained.

FIG. 6 shows a flowchart of a control program stored and executed in the controller 4 in the throttle control device according to the present invention shown in FIG. 5, and the above-mentioned embodiment will be described with reference to this flowchart. Will be described.

[Step S1] The driving wheel rotational speed ω is acquired from the driving wheel rotational speed sensor 2. When capturing the wheel speed, the one with the higher rotation speed is captured. Actually, the output shaft speed is taken in.

[Step S2] Drive wheel rotational acceleration a = d
ω / dt is calculated. This is obtained by time-differentiating the rotation speed ω taken in step S1.

[Step S 3] The accelerator pedal operation amount s is obtained from the accelerator sensor 1. At this time, the operation amount of the accelerator pedal is digitized and captured.

[Step S 4] The current shift position u is fetched from the shift position sensor 3.

[Step S5] A threshold value h of the driving wheel rotational acceleration defined by the accelerator pedal operation amount s and the shift position u is read from a look-up table (see FIG. 1). The threshold value h indicates the maximum permissible driving wheel rotational speed at which the driving wheels do not run idle in accordance with the accelerator pedal operation amount, and is obtained in advance through experiments and stored.

[Step S 6] x = a−h is calculated to calculate the degree of idling of the drive wheels. The larger the value, the more severe the slip.

[Step S7] It is determined whether or not x> 0, that is, whether or not the driving wheels are idling. As a result, if x is positive, it indicates that idling has occurred, and if x is negative, it indicates that idling has not occurred.

[Step S8] If the determination result in step S7 is “yes”, the throttle gain g = 1−
px (0 <g <1) is calculated. The normal non-control gain is set to 1 (characteristic T1 in FIG. 2), and the degree of throttle opening with respect to it is calculated.

[0041] [Step S9] g _r> determines whether or not g. g is a variable used only when the throttle gain is first calculated, and the gain during the return operation is g based on the gain return time determined by the fuzzy inference method.
Stored in _r .

[Step S10] If the determination result of comparing the gain g _r gradually changing in step S9 with the currently calculated gain g is “yes”, the smaller one (the one farther from 1) is determined. selected, it sets the g to g _r as the gain actually drops. . g _r has been calculated now smaller g is to be discarded.

[Step S11] The gain return time t is calculated by the fuzzy inference method (see FIG. 4) using the above s and x as inputs. Since g _r has been updated also the gain recovery time t there is a need to re-newly calculated. t is represented by a positive integer where one control cycle is 1.

[Step S12] This is a throttle driving routine, in which the throttle 7 is controlled via the actuator 5 in order to realize a throttle opening corresponding to the throttle gain calculated above. For example g _r = 0.8 would normally open only 80% of the throttle opening amount for operating the driver is depressing the accelerator pedal.

The result of the determination in step S9 is "no".
In this case, the process also proceeds to step S12.

[Step S13] If the decision result in the step S7 is "no", it is decided whether or not the gain return time t = 0 obtained in the step S11, that is, whether or not the gain return time is set.

[0047] When [Step S14] the determination result of step S13 is "yes" (t = 0), the gain recovery time will not have been set, and g _r = 1, normal proceeds to step S12 Operate with gain (= 1).

Note that the gain is set to 1 for the purpose of initialization because the flow goes through this flow in normal traveling.

[Step S15] If the determination result in step S13 is “no”, it means that the gain return time has been set, so it is determined whether or not a brake pedal (not shown) is depressed. If the brake pedal is depressed ("yes"), the control is frozen. In this case, g _r ,
t is held.

[Step S16] If the determination result in step S15 is “no”, the accelerator pedal operation amount is “0”
Is determined. Consequently, freeze control unless the accelerator pedal is depressed by an accelerator pedal operation amount is "0", holds g _r, a t.

[Step S17] If the result of the determination in step S16 is “no”, the throttle gain g _r = g _r +
To calculate the _{(1-g r) / t} .

[Step S18] The gain return time t is decremented, and the process proceeds to step S12. In this case, t does not become 0 or less.

[0053]

As described above, according to the throttle control device of the present invention, the threshold value is determined from the look-up table based on the current accelerator pedal operation amount and the shift position, and the current drive wheel rotational speed is determined based on the threshold value. When the acceleration is larger, the throttle opening gain is reduced in accordance with the difference, and the return time of the throttle is set by a method of obtaining a non-linear mapping based on the accelerator pedal operation amount and the difference. When the wheel rotation speed acceleration is smaller, the throttle opening gain is gradually returned to the original value during the return time, so that the burden on the driver to operate the accelerator on a slippery road surface is reduced, and a smooth start is achieved. It becomes possible and a traction control effect can be obtained.

If a throttle-by-wire system is installed, a sensor for detecting the rotation speed of the driven wheel and the like becomes unnecessary.

[Brief description of the drawings]

FIG. 1 is a graph showing a lookup table prepared for a throttle control device according to the present invention and storing a relationship between an accelerator pedal operation amount and a threshold value of a driving wheel rotational speed acceleration for each shift position.

FIG. 2 is a characteristic diagram showing a change in a throttle opening controlled by a throttle control device according to the present invention in relation to an accelerator pedal operation amount.

FIG. 3 is a graph illustrating a fuzzy inference method and a gain return time used in the throttle control device according to the present invention.

FIG. 4 is a graph for explaining the application principle of the fuzzy inference method used in the throttle control device according to the present invention.

FIG. 5 is a block diagram showing an embodiment of a throttle control device according to the present invention.

FIG. 6 is a flowchart of a control program stored and executed in a controller used in the throttle control device according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Accelerator sensor 2 Drive wheel rotational speed sensor 3 Shift position sensor 4 Controller 5 Throttle actuator 7 Throttle (valve) 8 Throttle opening sensor In the drawings, the same reference numerals indicate the same or corresponding parts.

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) F02D 9/00-11/10 F02D 29/00 F02D 41/00-45/00

Claims (3)

(57) [Claims] 1. A relationship between an accelerator sensor, a driving wheel speed sensor, a shift position sensor, an actuator for driving a throttle, a throttle opening sensor, an accelerator pedal operation amount, and a threshold value of a driving wheel speed acceleration. The threshold value is stored in a look-up table for each shift position, and the threshold value is determined from the look-up table based on the current accelerator pedal operation amount and the shift position detected by the accelerator sensor and the shift position sensor, respectively. When the driving wheel rotational speed acceleration is larger, the throttle opening gain is reduced by controlling the actuator in accordance with the difference, and a nonlinear mapping is obtained based on the accelerator pedal operation amount and the difference. The return time of the throttle is set, and the current drive wheel speed acceleration is smaller than the threshold value. And a controller for gradually returning the throttle opening gain to the original value during the return time. 2. The throttle control device according to claim 1, wherein the method is a fuzzy inference method or a neural network method. 3. The controller according to claim 2, wherein the controller holds the throttle opening gain and freezes the control when the brake pedal is depressed or the accelerator pedal is not depressed in the process of returning the throttle to the original position. Item 3. The throttle control device according to item 1 or 2.