JPH08121210A - Driving force control device for vehicle - Google Patents

Abstract

PURPOSE: To prevent thermal deterioration of a catalyst and realize satisfactory driving force control in an all temperature ranges by performing FCT (fuel cut) control so as not to increase catalyst temperature without prohibiting FCT at the high temperature of the catalyst. CONSTITUTION: When a judgment value τS exceeds an allowance degree τ1, namely, YES is answered in a step 350, a little time is reserved from the present time until it reach a limit value of prohibition of control. All cylinder injection is performed in this case toward the control prohibition (step 440). When the judgment value τS exceeds an allowance degree τ2, that is, YES is answered in a step 360, a little time is reserved from the present time until it reaches a judgment value for regulating control. Control regulation is aimed at in this case. Injection with small number of cylinders which may be performed when a number of of target FCT cylinder is one or two is suspended but all cylinder injection is performed (step 430). When the number of the target FCT cylinder is three or more, FCT executed with the present number of target FCT cylinders.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle driving force control device for controlling driving force by controlling fuel supply stop to an internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, an acceleration slip is detected from the difference between the rotational speed of a drive wheel and the rotational speed of a driven wheel, and when an acceleration slip occurs, fuel cut (hereinafter referred to as FCT) is performed. A driving force control device that controls the output torque of an internal combustion engine by control is known. If the protection of the catalyst is taken into consideration, for example, Japanese Patent Laid-Open No.
The device proposed in Japanese Patent No. 246335 discloses that the FCT control is prohibited to protect the catalyst when the catalyst temperature exceeds a predetermined value.

Further, in the device proposed in, for example, Japanese Unexamined Patent Publication No. 5-1613, when the floor temperature of the exhaust gas purifying device exceeds a predetermined value, the ignition retard and the air-fuel ratio of all cylinders are likely to rise. The lean engine is not used, but the engine output is reduced by using FCT for only one cylinder and leaning the air-fuel ratio for the rest.

At the time of low temperature of the internal combustion engine, if the same control as at normal temperature is attempted, that is, if the air-fuel ratio is made lean to reduce the catalyst temperature increase gradient, engine stall due to output reduction (higher possibility of misfire) occurs. It becomes a problem. Therefore, in order to prevent engine stalling, it is generally executed to correct the fuel injection amount to an increase amount side than usual. If acceleration slip occurs in this state and FCT control is executed, unburned HC components may be discharged from the injection cylinder, and FC
Since the fresh air sufficiently containing oxygen O ₂ is discharged from the cylinder executing T, the unburned HC component and O ₂ react with each other in the catalyst part of the exhaust system having a high temperature to burn. By doing so, there is a problem that the catalyst is overheated and deteriorates. Since such contradictory problems cannot be solved, conventionally, the FCT control itself was prohibited at low temperatures to cope with the problem.

However, for example, it is not preferable to prohibit the control itself even though it has a structure capable of executing the FCT control from the viewpoint of diluting the meaning of having the structure. There was room for improvement in devising ways to continue for a long time. Also, regarding the relationship between FCT and catalyst temperature, it was found that when the number of cylinders performing FCT is large, the amount of unburned gas is small and the catalyst temperature rise decreases as a whole.

Therefore, in the present invention, for example, when FCT control is performed as engine output control, FCT control is not uniformly prohibited when the catalyst temperature rises, but FCT control such that the catalyst temperature does not rise. By carrying out the above, it is intended to prevent thermal deterioration of the catalyst and realize good driving force control in the entire temperature range.

[0007]

In order to achieve the above object, the invention according to claim 1 controls the engine output by the fuel cut control for the internal combustion engine as illustrated in the basic configuration diagram of FIG. Engine output control means,
Catalyst state estimation means for estimating the influence of the engine output control on the catalyst temperature of the exhaust purification system, and engine output control amount change for changing the engine output control amount by the engine output control means based on the catalyst state estimated value And a driving force control device for a vehicle.

According to the second aspect of the present invention, the engine output control amount changing means is such that the catalyst state estimated value is a predetermined control suppression state by the engine output control means, as shown by a broken line in FIG. The engine output control amount is controlled according to the margin detected by the margin detecting means, which includes a margin detecting means for detecting a margin to be a control value or a time until the control reaches a predetermined value. The driving force control device for a vehicle according to claim 1, wherein the driving force control device is changed.

According to a third aspect of the present invention, the engine output control amount changing means is operable when the estimated catalyst state value reaches a first predetermined value or the margin becomes less than or equal to a first predetermined value. Is a drive force control device for a vehicle according to claim 1 or 2, wherein the engine output control amount is changed.

According to a fourth aspect of the present invention, the engine output control amount changing means is operable when the estimated catalyst state value reaches a first predetermined value or the margin becomes less than or equal to a first predetermined value. Changes the engine output control amount,
4. The vehicle driving force control device according to claim 3, wherein the engine output control means is caused to execute fuel cut control in a predetermined pattern.

According to a fifth aspect of the present invention, the predetermined pattern of the fuel cut control executed by the engine output control amount changing means by the engine output control amount changing means is a multi-cylinder fuel cut so that the catalyst temperature can be lowered as a whole. 5. The vehicle driving force control device according to claim 4, wherein the state is included in the pattern.

According to a sixth aspect of the present invention, the engine output control amount changing means is operable when the estimated catalyst state value reaches a second predetermined value or the margin becomes equal to or less than the second predetermined value. The vehicle drive force control device according to any one of claims 1 to 5, wherein control by the engine output control means is prohibited.

Further, the invention according to claim 7 is provided with an acceleration slip detecting means for detecting an acceleration slip as exemplified in the basic configuration diagram of FIG. 11, and the engine output control means suppresses the acceleration slip. The engine driving force control device according to any one of claims 1 to 6, characterized in that the engine output is controlled for this purpose.

Further, according to an eighth aspect of the present invention, as exemplified in the basic configuration diagram of FIG. 12, based on the braking force control means for applying the braking force to the drive wheels and the catalyst state estimated value, The driving force control device for a vehicle according to any one of claims 1 to 7, further comprising: a braking force control amount changing unit that changes a braking force control amount by the braking force control unit.

According to a ninth aspect of the present invention, the braking force control amount changing means includes the normal engine output control amount in the engine output control means and the engine output after being changed by the engine output control amount changing means. 9. The driving force control device for a vehicle according to claim 8, wherein the braking force control amount by the braking force control means is changed so as to compensate the influence on the vehicle motion characteristic due to the difference from the control amount.

[0016]

According to the invention described in claim 1,
The engine output control means controls the engine output by the fuel cut control for the internal combustion engine, and the catalyst state estimation means estimates the influence of the engine output control on the catalyst temperature of the exhaust purification system to change the engine output control amount. The means changes the engine output control amount by the engine output control means based on the catalyst state estimated value.

In other words, in the present invention, depending on the content of the engine output control, for example, a state may occur in which the catalyst temperature excessively rises and causes thermal deterioration.
For example, when such an estimated catalyst state value that the catalyst temperature rises excessively is obtained, the engine output control amount changing means changes the engine output control amount (that is, the control amount related to fuel cut) to change the catalyst temperature. It is possible to make it face down.

In order to clarify the operation of the engine output control amount changing means, the description will be continued by taking the cases of claims 2 to 5 as an example. For example, in the case of claim 2, the margin detection means provided in the engine output control amount changing means allows the estimated catalyst state value to reach a predetermined value at which the engine output control means is in a predetermined control suppression state or a control inhibition state. The margin, which is time or control amount, is detected. Then, the engine output control amount is changed according to the detected margin. Further, according to the third aspect, the engine output control amount is changed when the catalyst state estimated value reaches the first predetermined value or the margin becomes equal to or less than the first predetermined value.

As a modified example in that case, it is conceivable that the engine output control means is made to execute the fuel cut control in a predetermined pattern as shown in claim 4.
Furthermore, it is conceivable that the predetermined pattern of the fuel cut control includes, as shown in claim 5, a multi-cylinder fuel cut state in which the catalyst temperature can be lowered as a whole.

Thus, for example, the catalyst state estimated value is the first
The case where the predetermined value is reached or the margin is equal to or smaller than the first predetermined value reflects a state in which the catalyst temperature excessively increases due to the above-described engine output control and causes thermal deterioration. Therefore, from the viewpoint of protecting the catalyst, it is expected that the catalyst temperature is controlled to be lowered.

Conventionally, as described above, for example, when the internal combustion engine is at a low temperature, if the fuel injection amount is corrected to an increase amount side than usual to prevent engine stalling, and FCT control is executed to suppress slippage, the catalyst will overheat. In this case, the FCT control itself is prohibited in order to cope with the problem that it is deteriorated. That is, for example, in FCT control, FC
Despite the fact that T-control should be executed or is preferable to be executed, it is incompatible with the catalyst protection.
I was trying to ban the control. However, originally FCT
It is preferable to continue control.

On the other hand, regarding the FCT control, when the number of FCT cylinders is small, the catalyst temperature rise degree is high, and therefore it is problematic to continue the FCT control as it is, but when the number of FCT cylinders is large. It was found that since the amount of unburned gas was small, the degree of catalyst temperature rise decreased. Therefore, in the present invention, for example, when FCT control is performed as an example of engine output control, FCT control is not uniformly prohibited when the catalyst temperature rises, but a predetermined pattern with a low degree of increase in catalyst temperature is used. FCT
It controls.

As the fuel cut control of this predetermined pattern, for example, in the case where the control content includes a state in which the fuel cut is performed only in one cylinder or in only two cylinders in the normal fuel cut control, the fuel cut control of such a small number of cylinders is performed. It is conceivable that the fuel cut portion is stopped and, for example, injection is performed in all cylinders and the control content is limited to the fuel cut state of three or more cylinders. Further, as a completely fixed pattern, in the case of a 6-cylinder internal combustion engine, all cylinder cuts → 5 cylinder cuts → 4 cylinder cuts → 3
The control may be performed in a pattern such as cylinder cut → all cylinder injection → all cylinder cut → five cylinder cut.

Furthermore, as described in claim 5, since the multi-cylinder fuel cut state that can lower the catalyst temperature as a whole may be included in the pattern, for example, all cylinder cut → 5 cylinder cut → 4 Cylinder cut → 3 cylinder cut → 2
Control may be performed in a pattern such as cylinder cut → 1 cylinder cut → all cylinder injection → all cylinder cut → 5 cylinder cut. In this case, when viewed locally, the 1st and 2nd cylinder cuts in which the catalyst temperature is likely to rise are included. However, if the degree of decrease in the catalyst temperature due to the 3rd to 6th cylinder cuts before that is larger, then as a whole. Causes the catalyst temperature to decrease, so there is no problem. And, like this,
The merit of including the cylinder cut is, for example, 3
It is possible to avoid such a situation because the engine output may suddenly increase and the vehicle behavior may suddenly change when the cylinder cut suddenly returns to full-cylinder injection.

Therefore, according to each of these inventions, thermal deterioration of the catalyst can be prevented, and good FCT control can be realized in the entire temperature range, which is also preferable from the viewpoint of improving controllability. Particularly, when the engine output control amount is changed according to the margin, when the margin decreases, for example, when the margin decreases and becomes equal to or less than the first predetermined value as described in claim 3. Is capable of extending the controllable time of the engine output control by changing the control amount so as to reduce the degree of reduction of the margin, and improvement in controllability can be expected.

According to the sixth aspect of the present invention, the engine output control amount changing means, when the catalyst state estimated value reaches the second predetermined value or the margin becomes equal to or less than the second predetermined value. The control by the engine output control means is prohibited. When the catalyst state estimated value reaches the second predetermined value, the control must be immediately ended, for example, due to a high temperature state that causes catalyst damage. However, before that, the catalyst temperature rising gradient lowering control is executed to extend the control time longer than usual, and at this time, the "abnormality" can be transmitted to the driver.

According to the present invention, the acceleration slip detecting means detects the acceleration slip, and the engine output control means controls the engine output in order to suppress the acceleration slip. That is, in the present invention, in the acceleration slip control, the engine output is controlled according to the catalyst state estimated value or the margin, so that the acceleration slip control itself can be continued while realizing the catalyst protection, and the stable vehicle motion characteristics can be achieved. Various controls can also be realized.

In the eighth aspect of the present invention, the braking force control means can apply the braking force to the drive wheels, but the braking force control amount changing means is based on the catalyst state estimated value. The braking force control amount by the braking force control means is changed. Further, as described in claim 9, the braking force control amount changing means depends on the difference between the normal engine output control amount in the engine output control means and the engine output control amount after being changed by the engine output control amount changing means. It is desirable to change the braking force control amount by the braking force control means so as to compensate the influence on the vehicle motion characteristics.

This point will be supplemented. For example, if the portion that was executing the small cylinder FCT that raises the catalyst temperature is set to have no FCT (that is, all-cylinder injection) as an example of engine output control, in terms of slip suppression, the slip ratio is increased. Therefore, in such a case, by changing the braking force control amount by the braking force control means to a direction in which the braking force becomes larger, the decrease in the slip suppression effect by the engine output control is compensated.

As the braking force control means, braking force control is applied to all drive wheels independently, only some drive wheels independently (others are simultaneously), or all drive wheels are applied with brake hydraulic pressure at the same time. Can be adopted. Further, in each of the above inventions, the driver can be warned as a result before the engine output control means reaches the control prohibited state, so the safety in the driving force control is improved. In other words, by increasing / decreasing the number of fuel cut (FCT) cylinders and vibrating the engine, a gentle vibration of the vehicle (however, different from the vibration under normal control) is generated. Changes (within safety limits) can alert the driver.

This point will be supplemented. As in the device proposed in Japanese Patent Laid-Open No. Hei 5-1613 shown as the above-mentioned prior art, even if an attempt is made to achieve the same control performance as usual until the catalyst temperature rises, after all, the catalyst temperature rise cannot be prevented. The control is suddenly prohibited to make the vehicle behavior unstable, or the catalyst device is damaged. Further, also on the driver side, if there is no change in the control performance, the accelerator is often kept depressed (especially on a slope road, such a situation is likely to occur), and the above-mentioned adverse effects cannot be avoided.

On the other hand, in each of the above-mentioned inventions, a slight deterioration in performance is unavoidable compared with the normal control performance, but the deterioration is not so great as to make the vehicle behavior unstable, and the driver is provided with periodic vehicle vibrations. The limit of TRC control can be transmitted to. Further, since this FCT pattern can prevent (or decrease) the catalyst temperature rise, there is no need to suddenly stop the control or the catalyst is damaged as in the above-mentioned conventional technique.

Further, as in the inventions of claims 8 and 9,
When a braking force control function is provided, it is possible to prevent the deterioration of performance by correcting the above-mentioned performance-decreasing portion by braking force control. Further, since the vehicle vibration (vibration of the engine system) remains, the warning function for the driver can be secured.

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a vehicle driving force control device of the present invention will be described below with reference to the drawings. FIG. 1 shows a front engine / rear drive (FR) driven by an internal combustion engine 2.
FIG. 1 is an overall configuration diagram in which a vehicle driving force control device of the present embodiment is mounted on a vehicle of a type.

As shown in FIG. 1, an internal combustion engine (engine)
A sub-throttle valve 8 opened / closed by a drive motor 6 and a main throttle valve 12 opened / closed in conjunction with an accelerator pedal 10 from the upstream side of the intake passage 4 of FIG.
A surge tank 14 that suppresses the pulsation of intake air and a fuel injection valve 18 that injects fuel into the intake port 16 are provided, and an ignition coil 22 that supplies a high voltage in the cylinder 20.
A spark plug 24 connected to the is provided. In addition,
The engine 2 of this embodiment has 6 cylinders.

On the other hand, the exhaust pipe 51 is provided with an oxygen sensor for detecting the oxygen concentration in the exhaust gas, and a three-way catalyst 5 for purifying the exhaust gas.
2. Catalyst temperature sensor 54 for detecting the temperature of the catalyst 52
Is arranged. Also, for all wheels 26FL-RR,
A wheel cylinder 30 that applies a braking force to each of the wheels 26FL to RR by a hydraulic circuit 28 having a hydraulic pump and a solenoid valve (not shown) is provided.

Further, as sensors for detecting the operating state of the vehicle, an intake pressure sensor 32 for detecting the pressure of the surge tank 14, a main throttle opening sensor 34 for detecting the opening of the main throttle valve 12, and a sub throttle valve. 8, a sub-throttle opening sensor 36 for detecting the opening, a rotation speed sensor 38 for detecting the rotation speed of the crankshaft 2a of the engine 2 (engine rotation speed), and a gear shift for detecting the gear ratio of the transmission 40. A ratio sensor 42 is arranged.

Left and right rolling wheels (left and right front wheels) 26FL, 2
Rolling wheel speed sensors 44FL and 44FR for detecting the rotational speeds of the left and right rolling wheels 26FL and 26FR are arranged on the 6FR, and the left and right driving wheels 26RL and 26RR are rotated on the left and right driving wheels (left and right rear wheels) 26RL and 26RR. Drive wheel speed sensors 44RL and 44RR for detecting speeds (drive wheel speeds) are arranged.

The signals from the above sensors are input to the acceleration slip control circuit 50, and the acceleration slip control circuit 50 outputs a control signal to the actuator in order to perform the acceleration slip control described later. This acceleration slip control circuit 50, as shown in the block diagram of FIG.
It is configured as a microcomputer including a known CPU 50a, ROM 50b, RAM 50c, backup RAM 50d, input / output port 50e, and bus 50f connecting them.

The intake pressure sensor 32, which serves as a sensor, is connected to the input / output port 50e of the acceleration slip control circuit 50.
The main throttle opening sensor 34, the sub-throttle opening sensor 36, the rotation speed sensor 38, and the gear ratio sensor 42.
, A catalyst temperature sensor 54, a rolling wheel speed sensor 44FL,
The drive wheel speed sensors 44RL and 44RR are connected to 44FR. Further, as an actuator, a drive motor 6, a fuel injection valve 18, and a drive circuit (not shown),
The ignition coil 22 and the hydraulic circuit 28 are connected.

In the acceleration slip control circuit 50, the acceleration slip generated in the left and right drive wheels 26RL and 26RR is detected based on, for example, the acceleration slip ratio, and the sub throttle is adjusted so that the acceleration slip ratio falls within a predetermined range. By adjusting the opening degree of the valve 8 and the fuel injection amount by fuel cut, the output torque of the engine 2 is controlled to suppress acceleration slip (hereinafter referred to as engine output control). Also, the braking force is controlled by adjusting the hydraulic pressure of the wheel cylinders 30RL, 30RR of the left and right drive wheels 26RL, 26RR (hereinafter referred to as braking force control).

When an acceleration slip occurs on the drive wheels 26RL and 26RR due to a sudden accelerator operation of the driver on a low μ road, for example, the acceleration slip control circuit 50 outputs a fuel cut control (FCT control) command. , Engine output control for suppressing the output torque of the engine 2 is started. Then, thereafter, by outputting a control signal to the hydraulic circuit 28, the wheel cylinders 30RL, 3
The hydraulic pressure of 0RR is adjusted to start the braking force control for controlling the braking force on the drive wheels 26RL and 26RR.

Next, the operation of the vehicle driving force control system of the present embodiment having the above-mentioned structure will be described with reference to FIGS.
The flowchart will be mainly described. As shown in FIG. 3, when an ignition switch (not shown) is turned on, first, initialization processing such as memory clear and flag reset is performed (step 100). Next, each speed sensor 44FL,
The detection signals from 44FR, 44RL, and 44RR, that is, the rolling wheel speed VWF and the driving wheel speed VWD are input (step 11).
0). In order to distinguish between the left and right wheels, the left driving wheel speed VWDL and the right driving wheel speed VWDR are used.

Then, the acceleration slip control target speed VTS is calculated (step 120). The acceleration slip control target speed VTS is obtained, for example, by adding a predetermined offset value to the rolling wheel speed VWF. This offset value may be a fixed value or may be calculated from the target slip ratio. Further, the target slip ratio itself may be used. The acceleration slip control target speed VTS may be set as a common value for the left and right driving wheels, or may be set for each wheel independently.

Subsequently, in step 130, the acceleration slip amount S is calculated. The acceleration slip amount S may be set as a common value for the left and right driving wheels, or may be set for each wheel independently. The acceleration slip amount S is calculated as the difference between the smaller one of the left and right drive wheel speeds VWDR and VWDL and the acceleration slip control target speed VTS as in the following equation.

S = min (VWDR, VWDL) -VTS Then, S → 0 is the control target. In the above formula, in order to obtain the acceleration slip amount S, the smaller one of the left and right driving wheel speeds VWDR and VWDL is used to obtain the difference from the acceleration slip control target speed VTS. The average wheel speed [VDM = (VWDR + VWDL) / 2] may be used. In that case, the acceleration slip amount S is expressed by the following equation.

S = VDM-VTS The acceleration slip amount S calculated in step 130 is utilized to perform so-called TRC control for suppressing the acceleration slip. In step 140, the margin of engine output control (this margin Will be described later),
In step 150, engine (E / G) control processing is performed, and in step 160, braking force control processing is performed.

The processing contents of steps 140 to 160 will be described below in order. First, the calculation process of the margin of the engine output control in step 140 will be described with reference to FIGS. 4 and 5.

In step 210 of FIG. 4, as shown in FIG. 5, an evaluation value χE / G at the present time t0 as a margin factor in engine output control is detected. In this embodiment, since the margin is related to the catalyst temperature, the present catalyst temperature is calculated. This can be obtained from the detection value of the catalyst temperature sensor 54.

In the following step 220, the evaluation value χE / G
Calculate the change rate of. That is, the rate of change of the catalyst temperature indicated by the slope of the graph of FIG. 5 is obtained. Continued Step 230
Then, from the evaluation value χE / G and the rate of change thereof at the present time t0, the time point tA at which the judgment value χE / GA for limiting the control is reached and the limit value χE / GLM for inhibiting the control.
The time tLMT to reach T is calculated respectively, the required times τ1 and τ2 from the present time t0 are calculated, and this processing is once terminated. That is, from the current catalyst temperature and the rate of change thereof, the time to reach the predetermined determination temperature for limiting the control and the time to reach the limit temperature for inhibiting the control are obtained, and the margin τ1, at the present time t0, respectively. Let τ2.

Although the arrival times are given as examples of the margins τ1 and τ2 here, other than that, for example, FCT
Since the control is performed, it is possible to adopt the control allowable amount up to the limit state and the limit state, such as ΣFCT cylinder number × time t. Next, details of the E / G control processing in step 150 will be described with reference to the flowchart of FIG.

First, in step 310, it is determined whether or not the E / G control is currently being performed. If not, then it is determined in step 320 whether or not the control start condition is satisfied. To supplement the determination as to whether or not the control start condition is satisfied, it is determined whether or not the acceleration slip amount S calculated in step 120 exceeds a predetermined control start determination value SS.

When the control start condition is satisfied (step 3)
20: YES), the process proceeds to step 340, and the target FCT cylinder number FCTref is calculated. On the other hand, when the control start condition is not satisfied (step 320: NO), the process returns to step 110 in FIG.

Further, in step 310, a positive determination is made, that is, if the engine control is being performed, it is determined whether or not the control end condition is satisfied (step 330), and if the control end condition is satisfied, the following processing is performed. The process returns to step 110 of FIG. 3 without performing the above, but if the control termination condition is not satisfied, the process proceeds to step 340. To supplement the determination as to whether or not this control end condition is satisfied, the acceleration slip amount S calculated in step 120 falls below a predetermined control end judgment value SE, and the target FCT cylinder number FCTref = 0, and the target hydraulic pressure in the braking force control described later is obtained. When PBref = 0, it is determined that the control end condition is satisfied.

At step 340, as described above, the target F
The number of CT cylinders FCTref is calculated, and then step 350
Then, in step 360, the margins τ2 and τ1 calculated in step 230 of FIG.
Or less than. The determination value τS may be different or the same for the margin τ2 and the margin τ1.

The implications of the affirmative judgments in steps 350 and 360 will be described. Step 3
If the determination is affirmative at 50, it means that the time from the current time t0 to the limit value χE / GLMT for prohibiting the control is short, and in this case, the control is prohibited. . If the determination in step 360 is affirmative, there is still sufficient time to reach the limit value χE / GLMT for prohibiting control from the present time t0 (step 350: NO), but control is restricted. This is a state in which the time required to reach the determination value χE / GA for performing is shortened, and in this case, the control limit is approached.

If a negative determination is made in steps 350 and 360, the time from the present time t0 to the limit value χE / GLMT for inhibiting the control and the determination value χE / GA for limiting the control. There is a sufficient margin in the time to reach, and in this case, normal FCT control is executed. That is, in step 370,
The target FCT cylinder number FCTref calculated in step 340 is set as the actually executed FCT cylinder number FCTout. Then, after setting the brake mode to 0 in step 380, FCT output is performed in step 390, the actuator is driven, and this routine ends.

Next, the processing when the affirmative judgment is made in Step 360 will be explained. In this case, as described above, the direction of control limitation is headed, and specifically, the limit FCT cylinder number FCTris is set in step 400. This is for prohibiting the FCT of a small number of cylinders. For example, when prohibiting the FCT of one cylinder or two cylinders, FCT
Set CTris = 2. Then, in step 410, it is determined whether the target FCT cylinder number FCTref is less than or equal to the limit FCT cylinder number FCTris.

In step 410, a negative judgment is made, that is, FC
In the case of Tref> FCTris, there is substantially no need for limitation, so the routine proceeds to step 370, where FCTref is set as FCTout and the brake mode is set to "0" in the same manner as in normal control. FCT output is performed (steps 370-390).

On the other hand, if the affirmative determination is made in step 410, that is, if FCTref ≤ FCTris, the target number of FCT cylinders is 1 or 2. Therefore, the process proceeds to step 420, and "0" is set as the target number of FCT cylinders FCTout. Then, after setting the brake mode to "1", the process proceeds to step 390 and FCT output is performed. That is, when the target number of FCT cylinders is 1 or 2, FCTout
= 0, all cylinders are injected.

If an affirmative determination is made in step 350, the control is prohibited as described above. Specifically, in step 440, the target FCT cylinder number FC
After setting "0" as Tout and setting the brake mode to "2", the process proceeds to step 390 and FC
T output is performed. In other words, regardless of the target number of FCT cylinders,
With FCTout = 0, all cylinder injection is always performed.

Next, details of the braking force control processing in step 160 will be described with reference to the flowchart of FIG. First, in step 510, the current braking mode is determined. This brake mode is set to "0" by steps 380, 430, and 450 of FIG.
It is set to either "1" or "2".

First, when the brake mode is "0", the routine proceeds to step 520, where a normal constant (gain) is selected to calculate the target hydraulic pressure PBref. On the other hand, if the brake mode is "1", the process proceeds to step 530, the pressure increase side correction constant is selected to calculate the target hydraulic pressure PBref, and if the brake mode is "2", the process proceeds to step 540. After that, the correction constant on the sudden pressure increase side is selected in order to calculate the target hydraulic pressure PBref. Then, in step 550, the target hydraulic pressure PBref is calculated using the constant selected in any of steps 520 to 540, and brake output is performed in step 560, and this routine ends.

The above is the contents of the control processing of the present embodiment, but in order to clarify the action and effect of this processing, the description will be further continued with reference to FIGS. FIG.
6A is a time chart showing the number of FCT cylinders in an example of normal control executed by steps 370 to 390 of FIG. 6, and FIG. 6B is also a time chart of steps 400 to 43 of FIG.
8 is a time chart showing the number of FCT cylinders when the 1- and 2-cylinder FCT is prohibited as an example of the limit control executed by 0 and 370 to 390. In FIG. 8B, the case where the limit control is executed is shown by a solid line, and the case of the normal control is shown by a broken line for comparison.

In the normal control shown in FIG. 8A, the FCT
Since there is no limitation on the number of cylinders, FCT for only one cylinder or FCT for only two cylinders is also executed. On the other hand,
In the limit control shown in FIG. 8B, the timing at which the FCT of one cylinder or two cylinders should be set in FIG.
(B), the injection is performed in all cylinders at the timing shown by the diagonal lines.

In FIG. 8C, the change in the catalyst temperature in the case of the normal control of FIG. 8A is shown by the broken line, and the change in the catalyst temperature in the case of the limit control in FIG. 8B is shown by the solid line. As can be seen from the above, the degree of increase in the catalyst temperature is reduced by performing the all-cylinder injection instead of performing the FCT of only one cylinder or two cylinders, and the catalyst temperature does not increase much as a whole. Therefore, in the normal control shown by the broken line, a situation in which the catalyst temperature excessively rises and the control itself is prohibited comes relatively early, but by executing the limit control as in the present embodiment, the catalyst temperature is Situations that are too high to inhibit the control itself may be relatively slow, or such situations may be avoided.

The effect of this will be further described in comparison with the prior art. Conventionally, even though the FCT control should be executed or it is preferable to execute the FCT control, it is not compatible with preventing thermal deterioration of the catalyst due to excessive temperature rise. More importantly, the FCT control was prohibited. But,
Originally, it is preferable to continue the FCT control.

When the number of FCT cylinders is small, the catalyst temperature rise is high. Therefore, it is problematic to continue the FCT control as it is, but when the number of FCT cylinders is large, the amount of unburned gas is large. It was found that the degree of catalyst temperature rise decreased because the amount was small. Therefore, in this embodiment, when the FCT control is performed, if the catalyst temperature becomes high, the FCT will be uniform.
Instead of prohibiting the control, the FCT control is performed in a predetermined pattern so that the degree of increase in the catalyst temperature becomes low.

Therefore, thermal deterioration of the catalyst can be prevented, and good FCT control can be realized in the entire temperature range, which is also preferable from the viewpoint of improving controllability. In particular, when the margin τ1 decreases and falls below a predetermined judgment value τS, the control amount is changed so as to reduce the degree of decrease of the margin τ1 to extend the controllable time of the FCT control. It is possible to improve the controllability.

When the margin τ2 is below the predetermined judgment value τS, the FCT control itself is prohibited. When the margin τ2 falls below the predetermined determination value τS in this way, it is very likely that a high temperature condition that causes catalyst damage occurs or is likely to occur, and the control must be immediately terminated. Absent. However, before that, control was performed to decrease the temperature rise gradient of the catalyst, the control time was made longer than usual, and at this time the driver was "abnormal".
Can be transmitted.

Further, in the above-mentioned embodiment, as shown in FIG. 7, in the case of normal control, in the case of going in the direction of control limitation,
A (correction) constant used when calculating the target oil pressure PBref is selected according to the brake mode (0 to 2) set when the vehicle goes in the direction of control inhibition, and the target oil pressure is selected using the selected constant. PBref is calculated.

This is because, for example, as shown in FIG. 8 (B), the portion where the small cylinder FCT was executed in the normal FCT control (the portion indicated by diagonal lines) is regarded as having no FCT (that is, all cylinder injection). Then, in terms of slip suppression, the slip ratio increases. Therefore, in such a case, the target hydraulic pressure P, which is the control amount by the brake control,
By increasing Bref, the decrease in the slip suppression effect due to the engine output control is compensated.

Next, another embodiment of the FCT control of a predetermined pattern in the process for limiting the control executed when the affirmative judgment is made in step 360 of FIG. 6 will be described. In the above-described embodiment, when the control content includes a state in which only one cylinder or two cylinders are FCT, the fuel cut portion of such a small number of cylinders is stopped and all cylinder injection is performed instead. The control content was limited to the FCT state. Other than that, for example, as a completely fixed pattern, as shown in FIG. 9A, all cylinder cut → 5 cylinder cut → 4 cylinder cut → 3 cylinder cut → all cylinder injection → all cylinder cut → 5 cylinder cut The control may be performed in such a pattern.

As can be seen from FIG. 9B showing the change in the catalyst temperature due to this control, the catalyst temperature is lowered by the multi-cylinder FCT, so that the controllable time of the FCT control is extended as in the above embodiment. It is possible to improve the controllability. In the case of a fixed pattern, FCT
It can be expected to control the catalyst temperature rise due to "almost completely". That is, it is only necessary to set a fixed pattern such that the catalyst temperature does not rise according to the engine speed.

Further, as described above, even when the decrease in the slip suppressing effect by the engine output control is compensated by increasing the target hydraulic pressure PBref which is the control amount by the brake control, the FCT control with the fixed pattern is performed. In that case, cooperation with brake control can be easily realized,
It is also preferable in that more preferable control can be performed. It should be noted that, especially for the fixed pattern, another embodiment can be considered.
In the case of FIG. 9 (A) described above, the fixed pattern in which the 1- and 2-cylinder FCT is not performed, but since the multi-cylinder fuel cut state in which the catalyst temperature can be lowered as a whole may be included in the pattern. Alternatively, a fixed pattern as shown in FIG. 9C may be used. That is, all cylinder cut → 5 cylinder cut → 4 cylinder cut → 3 cylinder cut → 2 cylinder cut → 1 cylinder cut →
The control may be performed in a pattern such as all cylinder injection → all cylinder cut → 5 cylinder cut ....

In this case, when viewed locally, the 1st and 2nd cylinder cuts, in which the catalyst temperature is likely to rise, are included. However, if the degree of decrease in the catalyst temperature due to the 3rd to 6th cylinder cuts before that is larger, However, there is no problem because the temperature of the catalyst as a whole is lowered. And like this 1,
The merit of including the two-cylinder cut is to avoid such a situation, for example, when the all-cylinder injection is suddenly returned from the three-cylinder cut, the engine output may suddenly increase and the vehicle behavior may suddenly change. It can be mentioned.

In each of the above embodiments, the engine output control means is in the control prohibited state (in this case, FCT control prohibited).
As a result, the driver can be warned before the. In other words, by increasing / decreasing the number of FCT cylinders and vibrating the engine, a gentle (but different from conventional vibration) vibration of the vehicle is generated.
This change in the behavior of the vehicle (within the safe range) can alert the driver.

JP-A-5-16 shown as the above-mentioned prior art.
Like the device proposed in No. 13, even if an attempt is made to achieve a control performance equivalent to usual even when the catalyst temperature rises, if the catalyst temperature rise cannot be prevented after all, the control is suddenly prohibited to prevent the vehicle behavior. It will either stabilize or damage the catalytic device. Also for the driver side, if the control performance does not change, continue to step on the accelerator (especially on slopes, this situation tends to occur).
In many cases, the above adverse effects cannot be avoided.

On the other hand, in each of the above-mentioned embodiments, although a slight deterioration in performance is unavoidable as compared with the normal control performance, the deterioration is not so great as to make the vehicle behavior unstable, and the periodic vehicle vibration is applied. The limit of TRC control can be transmitted to the driver. Further, since this FCT pattern can prevent (or decrease) the catalyst temperature rise, there is no need to suddenly stop the control or the catalyst is damaged as in the above-mentioned conventional technique.

When a brake control function is provided, it is possible to prevent the deterioration of performance by correcting the above-mentioned performance-decreasing portion by brake control. Since the vehicle vibration remains, a warning function for the driver can be secured. It is needless to say that the present invention is not limited to the above-mentioned embodiments and can be carried out in various modes without departing from the gist of the present invention. For example, in the above embodiment, as the acceleration slip control, an example in which the driving wheel speed is adjusted so as to reduce the acceleration slip ratio has been described, but separately from that, the LSD control for reducing the left and right driving wheel speed difference is performed. Good. In this case, there are advantages such as improved running performance on a low μ road.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a configuration of an entire vehicle control system of an embodiment.

FIG. 2 is a block diagram showing an electrical configuration of the embodiment.

FIG. 3 is a main flowchart showing the overall processing of the embodiment.

FIG. 4 is a flowchart showing an engine control margin calculation process.

FIG. 5 is an explanatory diagram showing a margin.

FIG. 6 is a flowchart showing an engine (E / G) control process.

FIG. 7 is a flowchart showing a braking force control process.

FIG. 8 is a time chart showing the action and effect of the control processing of the embodiment.

FIG. 9 is a time chart showing the action and effect of the control processing of another embodiment.

FIG. 10 is a block diagram illustrating the configuration of the invention of claim 1;

FIG. 11 is a block diagram illustrating the configuration of the invention of claim 7;

FIG. 12 is a block diagram illustrating the configuration of the invention of claim 9;

[Explanation of symbols]

2 ... Internal combustion engine (engine) 4 ... Intake passage 18 ... Fuel injection valve 20 ... Cylinder 26RL, 26RR ... Drive wheel 26FL, 26FR ... Rolling wheel 28 ... Hydraulic circuit 44RL, 44RR ... Drive wheel speed sensor 44FL, 44FR ... Rolling wheel speed Sensor 50 ... Acceleration slip control circuit 52 ... Three-way catalyst 54 ... Catalyst temperature sensor

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location F02D 45/00 310 R 345 G

Claims (9)

[Claims] 1. An engine output control means for controlling an engine output by fuel cut control for an internal combustion engine, a catalyst state estimating means for estimating an influence of the engine output control on a catalyst temperature of an exhaust purification system, and the catalyst state estimation. An engine output control amount changing means for changing the engine output control amount by the engine output control means based on the value, and a driving force control device for a vehicle. 2. The engine output control amount changing means has a margin as a time or a control amount until the estimated catalyst state value reaches a predetermined value in which the engine output control means is in a predetermined control suppression state or a control inhibition state. 2. The vehicle driving force control device according to claim 1, further comprising: a margin detecting means for detecting the degree of margin, and changing the engine output control amount according to the margin detected by the margin detecting means. 3. The engine output control amount changing means, when the catalyst state estimated value reaches a first predetermined value, or the margin is equal to or less than a first predetermined value, the engine output control The amount is changed, and the amount is changed.
Alternatively, the vehicle driving force control device according to item 2. 4. The engine output control amount changing means, when the catalyst state estimated value reaches a first predetermined value, or when the margin becomes less than or equal to a first predetermined value, the engine output control amount is changed. 4. The vehicle driving force control device according to claim 3, wherein the engine output control means is caused to execute fuel cut control in a predetermined pattern as a change of the amount. 5. The predetermined pattern of the fuel cut control executed by the engine output control amount changing means by the engine output control amount changing means includes a multi-cylinder fuel cut state in which the catalyst temperature can be lowered as a whole. The driving force control device for a vehicle according to claim 4, comprising: 6. The engine output control amount changing means, when the catalyst state estimated value reaches a second predetermined value, or when the margin is equal to or less than a second predetermined value, the engine output control value is changed. 6. The vehicle driving force control device according to claim 1, wherein control by means is prohibited. 7. An acceleration slip detection means for detecting an acceleration slip is provided, and the engine output control means controls an engine output to suppress the acceleration slip. The vehicle driving force control device described. 8. A braking force control means for applying a braking force to the drive wheels, and a braking force control amount changing means for changing the braking force control amount by the braking force control means based on the catalyst state estimated value. The driving force control device for a vehicle according to any one of claims 1 to 7, further comprising: 9. The vehicle motion based on the difference between the normal engine output control amount in the engine output control unit and the engine output control amount after being changed by the engine output control amount changing unit in the braking force control amount changing unit. 9. The driving force control device for a vehicle according to claim 8, wherein the braking force control amount by the braking force control means is changed so as to compensate the influence on the characteristics.