JPH11141366A - Torque drop control device vehicle engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform cut of fuel, coping with a torque drop demand by a traction control, while the excessive increase of a catalyst is prevented from occurring. SOLUTION: In a region A being a most low rotation low load region, fuel cut is effected at S4 with the demand number of cylinder left as it is. In a region B being the higher rotation higher load side than that of the region A, fuel cut at the demand number of cylinders is allowed in a time t1 but after a laps of the time t1, fuel cut at the less number of cylinders (1-2 cylinders) is prohibited at S7. Further, in a region C being the higher rotation higher load side than that of the region B, fuel cut at the demand number of cylinders in a time t2 (<t1) fuel cut at the demand number of cylinders is allowed but after lapse of a time t2, only fuel cut of the whole number of cylinders is allowed at S10. Further, in a region D being the higher rotation higher load side than that of the region C, only fuel cut of whole cylinders is allowed from the beginning at S12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a torque reduction control device for a vehicle engine, and more particularly to a torque reduction control device for stopping a fuel supply to an engine to reduce a driving torque to meet a torque reduction request in traction control or the like. It relates to a down control device.

[0002]

2. Description of the Related Art Conventionally, driving wheels and non-driving wheels (driven wheels)
By detecting the rotational speed of the traction control device, the slip ratio of the drive wheels to the road surface is detected, and when the slip ratio is large, the drive torque is reduced by the fuel cut (F / C) to suppress the slip. Are known.

For example, in Japanese Patent Application Laid-Open No. Hei 7-217467, in order to prevent the catalyst performance from being adversely affected by the catalyst temperature rise due to the fuel cut in a high load and high revolution range, the number of required cut cylinders is reduced. An area on the high rotation / high load side where the execution of fuel cut is prohibited is set, and even if there is a cut request, the fuel cut is not performed when the area corresponds to the prohibited area.

Japanese Patent Application Laid-Open No. 6-26380 discloses that
A configuration is disclosed in which hunting of the engine speed is prevented by increasing the fuel return speed during fuel cut during traction control.

[0005]

By the way, in the case of the configuration in which the required fuel cut is prohibited in a specific operation region corresponding to the number of cut cylinders as described above, the fuel cut is performed for a relatively long time. It is necessary to widen the cut prohibition area with a margin so as not to affect the catalyst, so that the area where the fuel cut can be executed is limited, and the torque reduction for slip prevention cannot be sufficiently realized. There was a problem.

Also, in the case of a configuration in which the fuel return rotational speed is increased during traction control, the fuel cut for slip prevention is limited based on a uniform rotational speed. There was a problem that torque reduction could not be sufficiently realized. The present invention has been made in view of the above problems, and an area where torque reduction by fuel cut can be performed is expanded as much as possible without affecting an excessive temperature rise or stalling resistance of the catalyst. An object of the present invention is to improve traction control performance.

[0007]

Therefore, according to the present invention, there is provided a vehicle for a vehicle configured to selectively stop fuel supply to each cylinder based on the number of required fuel cut cylinders in response to a torque reduction request. In the torque reduction control device for the engine, the fuel cut by the required number of fuel cut cylinders is allowed for a shorter duration as the rotation speed and the load become higher, and after the allowable duration has elapsed, the number of fuel cut cylinders is limited. The configuration was added.

According to this configuration, even if the number of required fuel cut cylinders (for example, 1-2 cylinder cut out of 6 cylinders) causes a rise in the catalyst temperature when the fuel cut is continuously performed at high rotation speed and high load. If it is acceptable within a predetermined continuation time from the start of cutting, the fuel cut is executed with the same number of cylinders, but after the lapse of the continuation time, the fuel cut cylinder is operated so as to avoid a rise in the temperature of the catalyst. Limit the number. Here, the influence on the catalyst due to the fuel cut of a part of the cylinder becomes larger on the high rotation speed / high load side, and thus the duration is set to be shorter on the high rotation speed / high load side. However, the duration may include 0, and the duration may be set to 0 in some areas to limit the number of fuel cut cylinders from the beginning.

According to a second aspect of the present invention, there is provided a torque reduction control device for a vehicle engine configured to selectively stop fuel supply to each cylinder based on the number of fuel cut request cylinders corresponding to a torque reduction request. In the above structure, the number of required fuel cut cylinders is limited to the allowable maximum number of cylinders which is set to a smaller value as the rotation speed and the load become lower.

With this configuration, in the fuel cut at low rotation speed and low load, the engine stall resistance is reduced as the number of fuel cut cylinders increases. The value is set smaller as the load becomes lower, and the actual number of fuel cut cylinders is limited to the allowable maximum number or less. FIG.
It is configured as shown in FIG.

In FIG. 1, a required fuel cut cylinder number setting means sets the required number of fuel cut cylinders in response to a torque reduction request. The fuel cut means selectively stops the fuel supply by the fuel supply means provided for each cylinder according to the required fuel cut cylinder number set by the required fuel cut cylinder number setting means.

On the other hand, the engine operating region detecting means detects the operating region of the engine, and the allowable continuation time setting means determines the continuation time for allowing the fuel cut by the fuel cut request cylinder number as it is by the engine operating region detecting means. The setting is made based on the detected operating region of the engine. Then, the fuel cut limiting means, within the allowable duration,
While the fuel cut by the fuel cut means in accordance with the required number of fuel cut cylinders is permitted as it is, after the permissible continuation time has elapsed, the number of fuel cut cylinders is limited.

With this configuration, when the number of required fuel cut cylinders is set according to the torque reduction request, the engine operation range (for example, engine load,
Until the predetermined permissible continuation time according to (engine speed) elapses, the fuel cut is performed with the required number of cylinders, but after the permissible continuation time elapses, the number of fuel cut cylinders is limited, If necessary, forcibly cut the fuel other than the required number of cylinders, or completely prohibit the fuel cut in response to the fuel cut request.

According to a fourth aspect of the present invention, the allowable continuation time setting means sets the allowable continuation time to be shorter as the rotation speed and the load become higher. According to this configuration, the time during which fuel cut is performed with the required number of cylinders is shorter on the higher rotation speed and higher load side, and the number of fuel cut cylinders is immediately limited. This is because the higher the load and the higher the load side, the greater the effect of the fuel cut by a part of the cylinder on the catalyst, so that the time during which the fuel cut can be performed as required is short.

[0015] In the invention described in claim 5, the fuel cut restricting means sets the fuel cut cylinder number restriction pattern as:
A configuration is provided that has a restriction pattern that prohibits a partial cylinder fuel cut below a predetermined number of cylinders, and a restriction pattern that allows only all cylinder fuel cuts on the higher rotation speed and higher load side. According to such a configuration, the higher the rotation speed and the higher the load side, the greater the effect of the fuel cut on some cylinders on the catalyst, and the more the fuel cut on a small number of cylinders has a greater effect on the catalyst. In this example, only the fuel cut of all cylinders is permitted, and the fuel cut by a small number of cylinders is prohibited in a region where the influence is relatively small.

According to a sixth aspect of the present invention, the allowable duration setting means sets the duration based on the operating range of the engine and the required number of fuel cut cylinders. According to this configuration, even in the same engine operation range, the time that can be continued varies depending on the number of required fuel cut cylinders. Therefore, the allowable continuation time is set to a different value according to the engine operation range and the number of required fuel cut cylinders. Set.

On the other hand, the invention according to claim 7 is configured as shown in FIG. In FIG. 2, a fuel cut request cylinder number setting means sets the fuel cut request cylinder number in response to the torque reduction request. The fuel cut means selectively stops the fuel supply by the fuel supply means provided for each cylinder according to the required fuel cut cylinder number set by the required fuel cut cylinder number setting means.

On the other hand, the engine operating area detecting means detects the operating area of the engine, and the allowable maximum cylinder number setting means sets the allowable maximum number of fuel cut cylinders based on the operating area of the engine. The maximum number of cylinders limiting means limits the number of fuel cut cylinders in the fuel cut means to the allowable maximum number of cylinders or less set by the allowable maximum number of cylinders setting means.

According to such a configuration, the actual number of cylinders required for fuel cut in response to the torque reduction request is limited to the maximum allowable number of cylinders set for each operating region of the engine, and the actual fuel cut is performed. In the invention described in claim 8, the allowable maximum cylinder number setting means sets a smaller value as the allowable maximum cylinder number toward a lower rotation speed and lower load side.

According to this configuration, the allowable maximum number of cylinders decreases as the rotation speed and load decrease, and the region where the actual fuel cut cylinder number decreases as the rotation speed and load decreases, in other words, as the engine stall resistance decreases. Limited to small. According to a ninth aspect of the present invention, the allowable maximum cylinder number setting means sets the allowable maximum cylinder number to a smaller value as the engine temperature is lower.

According to this configuration, the allowable maximum number of cylinders is set to a smaller value as the engine temperature represented by the cooling water temperature or the like decreases and the engine stall resistance decreases.
Thus, the number of cylinders for which fuel is actually cut is limited to a small number. In the invention according to claim 10, the allowable maximum number of cylinders setting means sets the allowable maximum number of cylinders to a smaller value as the auxiliary load of the engine increases.

According to this configuration, the allowable maximum number of cylinders is set to a smaller value as the load on auxiliary equipment such as an air conditioner compressor and an electric load is increased and the engine stall resistance is reduced. Limit the number of fuel cut cylinders to a small number. In the invention according to claim 11, the fuel cut request cylinder number setting means is configured to include a slip rate detection means for detecting a wheel slip rate, and a drive is performed based on the slip rate detected by the slip rate detection means. The required number of fuel cut cylinders for reducing the torque to suppress the slip is set.

According to this configuration, if the drive wheels slip due to excessive drive torque, the required number of cylinders for performing fuel cut is set so as to eliminate the slip by reducing the drive torque, so-called traction control. Control is more accurate and precise. According to a twelfth aspect of the present invention, the fuel cut means alternately executes the same number of fuel cuts by a combination of different cylinders at predetermined intervals.

According to this configuration, for example, even in the same one-cylinder fuel cut, the fuel cut is alternately performed in different cylinders, instead of continuously performing the same cylinder. Here, in a V-type engine or the like, a configuration in which fuel cut is alternately performed between banks is preferable.

[0025]

According to the first aspect of the present invention, high rotation speed
There is an effect that the fuel cut can be executed as much as possible with the required number of cylinders of the fuel cut while suppressing the temperature rise of the catalyst at a high load. According to the second aspect of the present invention, low rotation
There is an effect that the fuel cut can be executed to the maximum while reliably preventing the engine stall due to the fuel cut at the time of the low load.

According to the third aspect of the present invention, it is possible to allow the fuel cut at the required number of cylinders to be maximized for each operating region of the engine, and to surely prevent the occurrence of temperature rise of the catalyst due to the fuel cut at the required number of cylinders. There is an effect that it can be prevented. Claim 4
According to the described invention, the fuel cut by the required number of cut cylinders is limited to a shorter time on the high rotation speed / high load side where the catalyst temperature rise due to the fuel cut in a small number of cylinders is large, and the catalyst temperature rise is reliably suppressed. In addition, there is an effect that the fuel cut at the required number of cylinders can be maximized.

According to the fifth aspect of the present invention, the catalyst temperature rise is greatest when fuel cut is performed in a small number of cylinders (1-2 cylinders in 6 cylinders). While fuel cuts in some cylinders are prohibited by permitting only a certain number of cylinders, while under conditions of relatively low engine speed and engine load, fuel cuts in some cylinders below a predetermined number of cylinders corresponding to the minority cylinders are prohibited, This has the effect of forcibly prohibiting the fuel cut or the total cut of the fuel cut over the predetermined number of cylinders or more, so that excessive catalyst temperature rise can be appropriately avoided.

According to the sixth aspect of the present invention, according to the catalyst temperature rising characteristic which differs depending on the number of cylinders in which fuel cut is performed,
There is an effect that the fuel cut at the required number of cut cylinders can be performed as long as possible. According to the seventh aspect of the present invention, there is an effect that the fuel cut at the required number of cut cylinders can be maximally permitted while taking into consideration the influence on the engine stall resistance which differs for each engine operation region.

According to the eighth aspect of the present invention, there is an effect that the number of cylinders for fuel cut can be appropriately limited in response to the lowering of the engine stall resistance at the lower rotation speed and lower load side. According to the ninth aspect of the present invention, the number of fuel cut cylinders can be limited to a small number at a low temperature at which the engine stall resistance is reduced, and generation of engine stall can be reliably prevented. There is an effect that the restriction on the number of cylinders is relaxed to obtain a large torque reduction.

According to the tenth aspect of the present invention, when the load of the auxiliary equipment is large and the engine stall resistance is reduced, the number of fuel cut cylinders can be limited to a small number to reliably prevent the occurrence of engine stall, and the load of the auxiliary equipment is relatively small. When it is small, there is an effect that the restriction on the number of cylinders for fuel cut is relaxed to obtain a large torque reduction. According to the invention as set forth in claim 11, the fuel cut for suppressing the slip can be performed in a wide range without inducing excessive temperature rise or engine stall of the catalyst, thereby improving the traction control performance by the fuel cut. There is an effect that can be made.

According to the twelfth aspect of the invention, it is possible to prevent the fuel cut from being continuously performed in a specific partial cylinder. For example, in a V-type engine having an exhaust system with a catalyst independent for each bank, Since the effect of the fuel cut can be dispersed to the catalyst of each bank, there is an effect that more fuel cut can be realized with the required number of cut cylinders, especially on the high rotation speed and high load side.

[0032]

Embodiments of the present invention will be described below. FIG. 3 is a system configuration diagram of the rear-wheel drive vehicle according to the embodiment. The engine 1 shown in the figure is a V-type six cylinder, and an injector (not shown) as a fuel supply means is provided for each cylinder. The injector may be configured to inject fuel directly into the combustion chamber of each cylinder, instead of injecting fuel into the intake port.

The exhaust from each cylinder is supplied to the left and right banks 1a,
After merging individually for each 1b and passing through the catalyst 2a for the left bank and the catalyst 2b for the right bank, the exhaust gases of the left and right banks merge and pass through the muffler 3 to be discharged into the atmosphere. The injector provided for each cylinder opens according to an injector drive signal from an ECM (Engine Control Module) 4 containing a microcomputer, and supplies fuel to each cylinder.

Detection signals from various sensors are input to the ECM 4, and the valve opening drive time of the injector, that is, the fuel injection amount is determined based on the detection signals. The various sensors include an air flow meter 5 for detecting an intake air amount QA of the engine 1, a crank angle sensor 6 for detecting a crank angle of the engine 1, a throttle sensor 8 for detecting an opening TVO of a throttle valve 7, and the like. ing.

In this embodiment, a traction control system (hereinafter, referred to as TCS)
The TCS control unit (TC
SC / U) 10 receives detection signals from wheel speed sensors 11a, 11b, 11c, and 11d provided for each of the four wheels, and outputs information on engine speed (rpm) and throttle opening from the ECM 4. Is input by communication via the LAN.

Also, a water temperature signal from the water temperature sensor 121,
An auxiliary load signal (including a battery voltage signal) from an auxiliary load sensor 122 for detecting an auxiliary load such as an air conditioner and a power steering is also input to the ECM 4. Then, the TCS control unit 10
Calculates the slip ratio of the drive wheels based on the various signals, and outputs a torque-down request signal corresponding to the slip ratio to the ECM 4.

ECM receiving the torque down request signal
4, the fuel cut F
By performing / C (temporary stop of fuel supply), the engine output torque is reduced, thereby reducing the drive torque of the drive wheels and suppressing the occurrence of slip. In FIG. 3, reference numeral 12 denotes a control unit (A / TC / U) of the automatic transmission.
In some cases, the T control unit 12 may output a fuel cut request signal to the ECM 4 during gear shifting.

FIG. 4 is a block diagram showing a control function of the ECM 4 and the TCS control unit 10. First, the control function of the TCS control unit 10 will be described.
The rotation speed of each wheel is detected based on signals from 11a to 11d.

The wheel speed comparison and calculation unit 102 compares the rotation speed of the front wheel (driven wheel) with the rotation speed of the rear wheel (drive wheel), and based on the result, the slip ratio calculation unit 103 (slip ratio detection means) Calculate the rate. The required torque-down calculation unit 104 calculates the required torque-down based on the calculated slip ratio.

The torque-down control signal output unit 105
Then, a torque down request signal indicating the torque down request amount is output to the ECM 4. Next, the fuel injection control by the ECM 4 will be described. First, an engine speed detector 111 detects an engine speed (rpm) NE (engine speed) based on a signal from the crank angle sensor 6, and an intake air amount detector 112 detects a signal from the air flow meter 5. , The intake air amount QA is detected.

The basic fuel injection pulse width calculation unit 113 calculates the basic pulse width Tp of the drive signal to be output to the injector,
The detected engine speed NE and intake air amount QA
Calculated based on The fuel injection pulse width calculator 114 corrects the basic pulse width Tp according to the engine coolant temperature, battery voltage, auxiliary equipment load, etc., and calculates the final injection pulse width Ti.

Then, the drive circuit 115 outputs a drive signal of the injection pulse width Ti to the injector 9 of each cylinder at an injection timing synchronized with the engine rotation. On the other hand, the torque down request signal from the torque down control signal output unit 105 of the TCS control unit 10 is E
The number of cylinders for requesting cut-off of torque is inputted to the torque-down request cylinder cut number calculating section 116 of the CM 4 to calculate the number of fuel cut cylinders (the number of required fuel cut cylinders) according to the required amount of torque reduction (fuel cut request cylinder number setting means).

The calculated fuel cut request cylinder number is:
It is output to the fuel cut cylinder number judging section 117 and the fuel cut duration counter section 119. The fuel cut cylinder number determining unit 117 (fuel cut limiting unit) determines the number of required fuel cut cylinders, the operating region of the engine, and the fuel cut duration measured by the fuel cut duration counter unit 119. Then, the number of cylinders at which the fuel cut is actually performed is determined. The operating range of the engine is determined by the throttle opening TVO representing the engine load and the engine speed NE input through the throttle opening detector 110. However, the engine load may be represented by the intake air amount QA, the basic pulse width Tp, or the like.

It should be noted that, in addition to the above parameters, the number of cylinders at which the fuel cut is actually performed may be determined in accordance with the water temperature, auxiliary equipment load, battery voltage, and the like. The number of cylinders that actually perform the fuel cut is determined by the fuel cut cylinder number determination unit 117.
Is determined, the fuel cut cylinder pattern designating section 118 designates a combination (pattern) of cylinders for which fuel cut is to be performed according to the number of fuel cut cylinders.

The fuel cut possibility final determination section 120 determines whether or not to finally execute the fuel cut based on the result of a failure diagnosis or the like which is separately performed. The fuel cut cylinder designated by the fuel cut cylinder pattern designation section 118 is output to the fuel injection pulse width calculation section 114, and the fuel injection amount (fuel injection pulse width) of the cylinder designated as the fuel cut cylinder is output. Is set to 0 (fuel cut means).

In the fuel cut cylinder pattern designating section 118, it is preferable to switch the combination of the cylinders for performing the fuel cut at predetermined time intervals so that the cylinders for performing the fuel cut are substantially uniform in the left and right banks. Specifically, when the required number of fuel cut cylinders is one, the fuel cut of the # 1 cylinder in the right bank is performed for a predetermined time, the fuel cut of the # 2 cylinder in the left bank is performed for a predetermined time, and the # 1 cylinder is again performed. The switching to the fuel cut of the cylinder is repeated, and the fuel cut of the # 1 cylinder in the right bank and the fuel cut of the # 2 cylinder in the left bank are alternately executed.

When the number of required fuel cut cylinders is two, the fuel cut of cylinders # 1 and # 3 in the right bank is performed.
The fuel cut of the # 2 cylinder and the # 4 cylinder of the left bank is alternately executed at predetermined time intervals. Fuel cut required cylinder number is 3
, The three cylinders in the right bank (# 1, # 3, #
5) All fuel cuts and three cylinders in the left bank (# 2, #
4, # 6) All fuel cuts are alternately executed at predetermined time intervals.

When the number of required fuel cut cylinders is four, the fuel cut of all the three cylinders (# 1, # 3, # 5) in the right bank and the # 2 cylinder in the left bank, and the three cylinders (# 2) in the left bank , # 4, # 6), and the fuel cut of the # 1 cylinder in the right bank and the right bank is alternately executed at predetermined time intervals. When the required number of fuel cut cylinders is 5, the fuel cuts of all three cylinders (# 1, # 3, # 5) in the right bank and # 4, # 6 cylinders in the left bank, and the three cylinders (# 2, # 2) in the left bank , # 4, #
6) All and the fuel cut of the # 3 and # 5 cylinders of the right bank are alternately executed at predetermined time intervals.

As described above, the pattern (combination) of the fuel cut cylinders is alternately executed at predetermined time intervals so that the fuel cut between the left and right banks is made substantially uniform. Can be prevented from continuously occurring in only one of the banks and excessively increasing the temperature of only one of the catalysts. Therefore, as compared with the case where the fuel cut is performed with a fixed combination of cylinders, up to a higher rotation speed and a higher load without adversely affecting the catalyst performance, and / or
It is possible to perform the fuel cut at the required number of cylinders for a longer time.

In the case of an in-line engine or a V-type engine provided with a catalyst downstream of the exhaust merging portion of each bank, the combination of the cut cylinders is switched.
Since the effect is not exhibited, the pattern switching need not be performed in such an engine. The flowchart of FIG. 5 shows the details of the control for determining the number of fuel cut cylinders in the fuel cut cylinder number determination section 117.

First, in S1, it is determined whether or not the TCS is operating. The operation of the TCS indicates that the torque-down control signal output unit 105 is outputting a torque-down request signal. In S1, the TCS is being operated, that is, the torque-down control signal output unit 105
When it is determined that the torque-down request signal is output from the CPU, the process proceeds to S2.

For example, as shown in FIG. 6, the entire operation region is divided into four regions A to D in advance according to the throttle opening TVO representing the engine load and the engine speed. It is determined which of the areas corresponds to the engine (engine operation area detecting means). In S3, it is determined whether or not the engine falls within the area A. If the area is the area A, the process proceeds to S4, where the required number of cylinders for fuel cut calculated by the required number of cylinders for cut-down of torque calculated by the torque cut-off required cylinder number calculation section 116 is used as the final number. It is assumed that the number of cuts does not impose any limit on the number of fuel cut cylinders.

This is because the region A is a low-rotation, high-medium, low-load, low-load, high-medium, low-rotation region, and the fuel in the one or two cylinders, which is the number of fuel cut cylinders at which the temperature rise of the catalyst is greatest. This is because even if the cut is continuously performed, the temperature does not become high enough to adversely affect the catalyst performance (for example, 900 ° C.), and the fuel cut is actually performed according to the required number of cylinders.

On the other hand, if it is determined in step S3 that the area is not the area A, the process proceeds to step S5, and it is determined whether or not the area is the area B which is a medium rotation / medium load area. And when it is the B area,
Proceeding to S6, the elapsed time from the start of the operation of the TCS, that is, the time from when the torque-down control signal output unit 105 starts to output the torque-down request signal, is set as the TCS operation time, and the fuel cut duration counter unit 119 measures it. .

In the next S7, the torque-down required cylinder cut number calculating section 116 calculates the TCS operation time until the measured TCS operation time reaches a predetermined time t1 (for example, about 8 seconds) which is an allowable continuation time. The number of required fuel cut cylinders is used as the final number of cuts as is, and there is no restriction on the number of fuel cut cylinders. However, after the predetermined time t1 has elapsed, the number of cylinders at which the temperature rise of the catalyst becomes the largest is the small number of cylinders. A limit processing of the number of cut cylinders in which the fuel cut is prohibited is executed.

In the region B, although the minor cylinder fuel cut cannot be performed indefinitely, even if the minor cylinder fuel cut is performed, the catalyst temperature does not immediately exceed the allowable temperature. If it continues for a long time, it will eventually approach the allowable temperature, so fuel cut according to the required number of cylinders will be continued within the allowable range, and then the number of cut cylinders will affect the catalyst temperature. The number of cylinders is not limited.

The prohibition measures for the fuel cut of the few cylinders are as follows.
Specifically, in the case of the six-cylinder engine of the present embodiment, 1
When the number of required fuel cut cylinders is one or two, three-cylinder fuel cut is forcibly performed or no fuel cut is performed. However, if the fuel cut is completely prohibited, no slip suppression effect will be obtained at all, so it is preferable to force the three-cylinder fuel cut. If the configuration is such that the three-cylinder fuel cut is forcibly performed, three to three cylinders
Since the change is made to the cylinder, an excessive decrease in torque is sufficiently small, and the occurrence of a shock due to a fuel cut can be sufficiently reduced. In addition, a three-cylinder fuel cut state and a state in which no fuel cut is performed are alternately performed.
It is also possible to obtain a torque reduction effect similar to that in the / 2 cylinder fuel cut state.

In the case of four cylinders, the fuel cut of one or two cylinders may be prohibited, and in the case of eight cylinders, the fuel cut of about one to four cylinders may be prohibited. If it is determined in step S5 that the area is not the area B, the process proceeds to step S8, and it is determined whether or not the area C is higher in rotation speed and load than the area B. If it is the C area, the process proceeds to S9, where TC
The S operation time is counted by the fuel cut duration time counter 119.
To measure.

In the next step S10, the torque-down request cylinder cut number calculating section 116 calculates the TCS operation time until the measured TCS operation time reaches a predetermined time t2 (for example, about 1 second) which is an allowable continuation time. The fuel cut request cylinder number is used as the final cut number as it is, and no limit is imposed on the fuel cut cylinder number. However, after the predetermined time t2 has elapsed, the cut cylinder number that allows only all cylinder fuel cuts is limited. Execute the process.

In the area C, unlike in the area A, the fuel cut in the small number of cylinders cannot be performed indefinitely. Further, since the rotation speed and the load are higher than those in the area B, the time in which the fuel cut in the small number of cylinders can be continued. Is shorter, and even if a partial cylinder cut is performed with a relatively large number of cylinders, the catalyst temperature rises. Therefore, the time for performing the fuel cut with the required number of fuel cut cylinders is shortened as compared with the region B, the fuel cut is limited to the fuel cut for all cylinders, and the fuel cut for some cylinders is prohibited. .

The restricting measure for permitting only the all-cylinder fuel cut means that the all-cylinder fuel cut is forcibly performed in response to the fuel cut request or the fuel cut is completely prohibited. However, it is preferable to execute a full-cylinder fuel cut as far as possible without causing a large shock due to the fuel cut. For example, if the required number of fuel cut cylinders is 4 to 5 cylinders, a full-cylinder fuel cut is forcibly performed. In the case of a three-cylinder engine, it is preferable not to perform the fuel cut at all.

If it is determined in step S8 that the area is not the area C, the process proceeds to step S11, and it is determined whether or not the area is the area D which is at the highest rotation speed and load. If it is in the D region, the process proceeds to S12, and a process of limiting the number of cut cylinders that permits only all-cylinder fuel cut is executed from the beginning. D area is C
Since it is on the higher rotation speed and higher load side than the region, there is no margin to allow the minor cylinder fuel cut. Even if the minor cylinder fuel cut is performed for a short time, the allowable temperature (for example, 900 ° C.)
, The process immediately enters the processing mode of permitting only all-cylinder fuel cut.

The steps S3 to S12 correspond to fuel cut limiting means and allowable continuation time setting means. As described above, when the number of fuel cut cylinders is limited based on the operating range of the engine, the required number of fuel cut cylinders, and the TCS operation time, the final number of fuel cut cylinders (required cylinder number) is determined in S13. On the other hand, in S14, the TCS operation time is measured for switching the combination of the cut cylinders described above.
Then, one of the combinations is set to the A mode and the other is set to the B mode, and the mode to be used is switched and set at regular intervals based on the TCS time.

In S16, it is determined whether or not the A mode is selected by the switching setting in S15. If the A mode is in progress, the process proceeds to S17, in which the fuel cut is performed in the A mode cylinder combination. When it is not in the A mode but in the B mode, the process proceeds to S18, and the fuel cut is performed by the cylinder combination in the B mode. Incidentally, the steps S13 to S18 correspond to fuel cut means.

According to the above configuration, even in a region where it is not possible to perform a continuous fuel cut with the required number of fuel cut cylinders as in the regions B, C, and D, the B, C, and D regions are used.
In a case where the fuel cut by the required number of cylinders can be performed for a limited time as in the region C, the fuel cut according to the request is directly executed in the initial stage of the TCS request,
After the permissible time has elapsed, the number of cylinders is limited so as not to cause excessive temperature rise of the catalyst, so that the region where fuel cut can be performed in accordance with the required number of cylinders can be increased. Thus, it is possible to more effectively reduce the torque for suppressing the slip while avoiding the temperature rise.

The times t1, t2 (allowable continuation time)
May be fixed values. However, even within the same B and C regions, the time during which continuation can be allowed may greatly vary depending on the number of required fuel cut cylinders. The configuration may be such that the times t1 and t2 are changed. For example, in the region B, the fuel cut request for three to six cylinders is continuously executed without being restricted by the time t1, and when the required cut number is one or two, the fuel cut request is limited by the time t1. However, even when the same time t1 has elapsed, the catalyst temperature rise level differs depending on whether the number of cuts is one or two, and there is a case where the required fuel cut can be permitted for a longer time. Therefore, a difference is provided in the time t1 depending on whether the required number of cuts is one cylinder or two cylinders.

Further, the conditions of the engine speed may be set more finely, and the times t1 and t2 may be changed depending on the conditions of the engine speed even in the same B and C regions. Further, the times t1 and t2 and the number of allowable cut cylinders are
The control may be variably controlled based on information such as an auxiliary load, a battery voltage, and a water temperature. By the way, in the region A, it is not required to limit the number of cut cylinders in consideration of a rise in the catalyst temperature. However, in the low rotation speed and low load side in the region A, there is a possibility of engine stall when the number of cut cylinders is large. It is required to execute the fuel cut to the maximum for the slip suppression while securing the engine stall performance.

Therefore, the fuel cut control in consideration of the engine stall resistance in the low rotation speed and low load range will be described below with reference to FIG.
This will be described according to the flowchart of FIG. Note that the fuel cut control shown in the flowchart of FIG. 7 is also performed centering on the fuel cut cylinder number judging unit 117 in the system block diagram of FIG. 4, so that the control is performed with reference to FIGS. The contents will be described below.

In the flowchart of FIG. 7, in S21, it is determined whether or not the TCS is operating (the output state of the torque down request signal). Then, when the TCS is in operation, the process proceeds to S22, and as shown in FIG.
It is determined which of the four areas a to d in the low load area corresponds (engine operating area detecting means).

In step S23, it is determined whether or not the region a corresponds to the highest rotation / high load side in the low rotation / low load region. If the region is the region a, the process proceeds to S24. In S24, the final number of fuel cut cylinders is set without any restriction on the number of required fuel cut cylinders. The a region,
Even if the required number of cuts is the highest in the low-rotation / low-load region and the required number of cuts is all cylinders, the engine will normally restart fuel injection based on the engine speed to generate engine stall. Therefore, it is assumed that all required cuts including the all-cylinder fuel cut are allowed as they are.

On the other hand, if it is determined in step S23 that the area is not the area a, the process proceeds to step S25, and it is determined whether or not the area corresponds to the area b having a lower rotation speed and a lower load than the area a. And b
If it is in the region, the process proceeds to S26, in which the fuel cut of 1 to 4 cylinders is allowed with the 6-cylinder engine of the present embodiment, and
Prohibit cylinder fuel cut. For example, when the required number of fuel cut cylinders is one of 1 to 4 cylinders, the required number of cuts is used as the actual number of cuts, but when the required number of fuel cut cylinders is 5 or 6 cylinders, the number of 5 cylinders is used. Alternatively, if the fuel cut is performed in the six cylinders, the rotation drop may be sharp and the engine may stall in the worst case. Therefore, the fuel cut in the five or six cylinders is prohibited. This limits the fuel cut cylinder to four or less corresponding cylinders.

When the required number of cuts is 5 or 6 cylinders and the fuel cut with the same number of cylinders is prohibited, the fuel cut may not be performed on all cylinders. It is preferable that the four-cylinder cut, which is the maximum number of the cylinders, be performed because slip can be suppressed while engine stall is reliably avoided. Also, S25
If it is determined that the region is not the region b, the process proceeds to S27, and it is determined whether or not the region corresponds to the region c which has a lower rotation speed and a lower load than the region b.

If it is the area c, the process proceeds to S28, where
Fuel cut of two cylinders is allowed (allowable maximum number of cylinders = two cylinders), and fuel cut of three to six cylinders is prohibited. The c region has a lower rotation speed and a lower load than the b region, so even with a smaller number of cuts, there is a possibility of the worst engine stalling. It is. Also in this case, the required number of cuts is 1-2.
If the cylinder is a cylinder, the fuel cut is performed as it is, but if the required number of cuts is 3 to 6 cylinders, it is preferable to perform the fuel cut in two cylinders which is smaller than the required but is the maximum allowable number of cuts. .

If it is determined in step S27 that the area does not correspond to the area c, the process proceeds to step S29, and it is determined whether or not the area corresponds to the area d where the rotation and load are lower than in the area c. If the region does not correspond to the region d, it is a medium-high rotation / medium-high load region that does not correspond to any of the regions a to d, and is not a low rotation / low load region to be controlled by the present embodiment. To end.

Here, the medium-high rotation / medium-high load area which does not correspond to any of the areas a to d substantially corresponds to the area where there is no possibility of engine stall similarly to the area a. 7 and the flowchart of FIG. 5 and FIG.
In the low-speed / low-load region, the fuel cut cylinder is limited in consideration of the engine stall resistance, as shown in FIG. Figure 5 to avoid ascent
It is advisable to limit the fuel cut cylinder as shown in FIG.

On the other hand, if it is determined in S29 that the region is the d region, the process proceeds to S30, and a measure for completely inhibiting the fuel cut is executed (allowable maximum number of cylinders = 0). The d region,
Since the rotation is lower and the load is lower than in the region c, there is a possibility that the rotation is greatly reduced even when the fuel is cut in a small number of cylinders.
This is prohibited regardless of the number of fuel cut cylinders from 1 to 6.

The steps S23 to S30 correspond to the maximum cylinder number limiting means and the maximum allowable cylinder number setting means. When the final number of fuel cut cylinders is determined as described above, S31
In S36 to S36, the fuel cut is executed while alternately switching the combination of the fuel cut cylinders in the same manner as in S13 to S18.

According to the above configuration, since the maximum number of cuts that can ensure the engine stall resistance differs for each operating region, the maximum number of cuts is limited to the maximum number of cuts set for each operating region. In addition, the fuel cut can be performed with the maximum number of cuts for each area. In the flowchart of FIG. 7, the maximum allowable number of cylinders is determined only from the operating range divided by the engine load and the engine speed. However, the engine stall resistance is low when the engine temperature represented by the cooling water temperature is low. The load decreases as the load on auxiliary equipment such as an air conditioner compressor and an electrical load increases. Therefore, as the cooling water temperature is lower and the auxiliary equipment load is higher, the region d shown in FIG. 8 is expanded, and the region where the fuel cut is permitted is shifted to higher rotation and higher load. It is better to change to

[Brief description of the drawings]

FIG. 1 is a basic configuration block diagram of a torque down control device according to claim 3.

FIG. 2 is a basic configuration block diagram of a torque down control device according to claim 7;

FIG. 3 is a system configuration diagram of the vehicle in the embodiment.

FIG. 4 is a control block diagram according to the embodiment;

FIG. 5 is a flowchart showing fuel cut control at the time of high rotation and high load in the embodiment.

FIG. 6 is a diagram showing an example of division of a high rotation / high load region.

FIG. 7 is a flowchart showing fuel cut control at the time of low rotation and low load in the embodiment.

FIG. 8 is a diagram showing an example of division of a low rotation / low load region.

[Explanation of symbols]

 Reference Signs List 1 engine 1a left bank 1b right bank 2a, 2b catalyst 4 ECM 5 air flow meter 6 crank angle sensor 7 throttle valve 8 throttle sensor 9 injector 10 TCS control unit 11a to 11d wheel speed sensor 121 water temperature sensor 122 auxiliary load sensor

Claims (12)

[Claims] 1. A vehicle engine torque-down control device configured to selectively stop fuel supply to each cylinder based on the number of cylinders required for fuel cut in response to a torque-down request. Wherein the fuel cut by the engine is allowed for a shorter duration as the engine speed and load become higher, but after the elapse of the allowable duration, the number of fuel cut cylinders is limited. . 2. A torque reduction control device for a vehicle engine configured to selectively stop fuel supply to each cylinder based on the number of cylinders required for fuel cut in response to a request for torque reduction. A torque reduction control device for a vehicle engine, wherein the torque is controlled to be equal to or less than an allowable maximum number of cylinders that is set to a smaller value as the rotation speed and the load become lower. 3. A fuel cut request cylinder number setting means for setting a fuel cut request cylinder number in response to a torque reduction request, and a fuel cut request cylinder number set by the fuel cut request cylinder number setting means. Fuel cut means for selectively stopping fuel supply by fuel supply means provided for each cylinder; engine operating area detecting means for detecting an engine operating area; and allowing fuel cut by the fuel cut request cylinder number as it is An allowable continuation time setting means for setting the continuation time based on the engine operation area detected by the engine operation area detection means; and within the allowable continuation time set by the allowable continuation time setting means, While the fuel cut according to the fuel cut request cylinder number is permitted as it is, after the permissible continuation time elapses, the fuel cut is performed. A fuel cut-off control device for a vehicle engine, comprising: a fuel cut limiter that limits the number of cylinders. 4. The torque reduction control device for a vehicle engine according to claim 3, wherein said permissible duration setting means sets said permissible duration to be shorter as the rotation speed and load become higher. 5. The fuel cut restricting means includes a restricting pattern for prohibiting a partial cylinder fuel cut below a predetermined number of cylinders, as a restricting pattern for the number of fuel cut cylinders.
The torque reduction control device for a vehicle engine according to claim 3, further comprising a restriction pattern that permits only all-cylinder fuel cut on a high load side. 6. The apparatus according to claim 3, wherein said allowable duration setting means sets said duration based on an operation range of said engine and said required number of cylinders of fuel cut.
The torque reduction control device for a vehicle engine according to any one of claims 1 to 5. 7. A fuel cut request cylinder number setting means for setting a fuel cut request cylinder number in response to a torque reduction request, and a fuel cut request cylinder number set by the fuel cut request cylinder number setting means. Fuel cut means for selectively stopping fuel supply by fuel supply means provided for each cylinder; engine operation area detection means for detecting an engine operation area; and operation of the engine detected by the engine operation area detection means An allowable maximum cylinder number setting unit that sets an allowable maximum number of fuel cuts based on the area; and a fuel cut cylinder number in the fuel cut unit, the allowable maximum cylinder number set by the allowable maximum cylinder number setting unit or less A torque reduction control device for a vehicle engine, comprising: means for limiting the maximum number of cylinders. 8. The system according to claim 1, wherein said maximum allowable cylinder number setting means includes:
8. The torque reduction control device for a vehicle engine according to claim 7, wherein a smaller value is set as the allowable maximum number of cylinders on a lower load side. 9. The vehicle engine torque reduction according to claim 7, wherein said allowable maximum cylinder number setting means sets said allowable maximum cylinder number to a smaller value as the engine temperature is lower. Control device. 10. The apparatus according to claim 7, wherein said allowable maximum number of cylinders setting means sets said allowable maximum number of cylinders to a smaller value as an auxiliary load of said engine increases. The torque reduction control device for a vehicle engine according to any one of the preceding claims. 11. The fuel cut request cylinder number setting means includes a slip rate detecting means for detecting a wheel slip rate, and reduces a driving torque based on the slip rate detected by the slip rate detecting means. The torque reduction control device for a vehicle engine according to any one of claims 3 to 10, wherein a required number of fuel cut cylinders is set to suppress slippage. 12. The fuel cut device according to claim 3, wherein the fuel cut means alternately executes a fuel cut of the same number of cylinders by a combination of different cylinders at predetermined intervals. Of the vehicle engine torque down control.