JP2010025071A - Control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a fuel cut by unconscious accelerator operation of a driver. <P>SOLUTION: An ECU 21 detects present accelerator opening, and calculates accelerator opening becoming a constant vehicle speed travel state based on a shift stage of an automatic transmission 11, a road surface gradient and a vehicle speed, and determines whether the vehicle speed is a substantially constant speed travel state of substantially constant or an unconstant speed travel state being not substantially constant in a vehicle speed, by comparing the present accelerator opening with the accelerator opening of becoming the constant vehicle speed travel state. The fuel cut is prohibited by determining as being switched to the unconstant speed travel state by the unconscious accelerator opening of the driver until a predetermined time passes after its determining result is switched to the unconstant speed travel state from the substantially constant speed travel state. Thus, the fuel cut is not performed even when a speed reduction time fuel cut performing condition is realized when switched to a speed reduction travel state from the substantially constant speed travel state by the unconscious accelerator operation of the driver in substantially constant speed travel. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine having an improved function of executing a fuel cut for stopping fuel injection of the internal combustion engine.

  Generally, in a vehicle equipped with an internal combustion engine, when a predetermined fuel cut execution condition during deceleration is satisfied (for example, a region where the accelerator opening is equal to or smaller than a predetermined value and the rotational speed of the internal combustion engine is equal to or higher than the fuel cut return rotational speed) ), A fuel cut for stopping the fuel injection of the internal combustion engine is executed to improve fuel efficiency.

In addition, when the driver keeps the amount of depression of the accelerator pedal constant and the vehicle is traveling at a constant vehicle speed, the driver may unintentionally move the accelerator pedal little by little. In order to prevent deterioration of drivability due to unintentional accelerator operation by a driver, as described in Patent Document 1 (Japanese Patent No. 3115415), the accelerator operation speed is smaller than a predetermined value and the accelerator operation amount Is smaller than the predetermined value, it is determined that the driver is unconsciously operating the accelerator, and the automatic transmission is prohibited, the lockup clutch is released, and the throttle opening degree of change is corrected to reduce the vehicle behavior. There is something that makes the change slow.
Japanese Patent No. 3115415

  However, as in the above-mentioned Patent Document 1, when the driver's unconscious accelerator operation is detected, even if the shift of the automatic transmission is prohibited, the lock-up clutch is released, and the degree of change in the throttle opening is reduced, The fuel cut execution condition during deceleration may be established intermittently due to the driver's unconscious accelerator operation, and as a result, the fuel cut execution and return are repeated by the driver's unconscious accelerator operation, and the internal combustion engine The output torque may fluctuate and drivability may deteriorate.

  The present invention has been made in view of such circumstances, and therefore the object of the present invention is to prevent repeated execution / return of fuel cut due to the driver's unconscious accelerator operation. It is an object of the present invention to provide a control device for an internal combustion engine that can prevent the deterioration of performance.

  In order to achieve the above object, the invention according to claim 1 is a control of an internal combustion engine having a function of executing a fuel cut that stops fuel injection of the internal combustion engine when a predetermined deceleration fuel cut execution condition is satisfied. In the apparatus, the traveling state determination means determines whether or not the traveling state of the vehicle is an approximately constant speed traveling state in which the vehicle speed is approximately constant, and the determination result indicates that the vehicle speed is not approximately constant from the approximately constant speed traveling state. A structure provided with a fuel cut prohibiting means for prohibiting fuel cut by determining that the driver has switched to the non-constant speed driving state by the driver's unconscious accelerator operation until a predetermined period has elapsed since switching to the high speed driving state It is a thing.

  When the non-constant speed driving state is switched from the substantially constant speed driving state (for example, the deceleration driving state or the acceleration driving state) and the non-constant speed driving state continues for a certain period of time, the driver's conscious accelerator operation Although it is highly possible that the vehicle is maintained in a non-constant speed driving state, for a while after switching from the substantially constant speed driving state to the non-constant speed driving state, the driver's unconscious acceleration operation causes the non-constant speed driving state. It may have switched to a state.

  Focusing on this point, the present invention relates to the driver's unconscious accelerator operation until a predetermined period elapses after the determination result of the driving state determination means switches from the substantially constant speed driving state to the non-constant speed driving state. Because it is determined that the vehicle has switched to the non-constant speed driving state, the fuel cut is prohibited.Therefore, during the substantially constant speed driving, the driver switches to the deceleration driving state from the substantially constant speed driving state by an unconscious accelerator operation. Even when the deceleration fuel cut execution condition is satisfied, the fuel cut can be prevented from being executed. This makes it possible to avoid repeated execution of fuel cut and return due to the driver's unintentional accelerator operation while driving at a substantially constant speed, thereby preventing deterioration of drivability due to the driver's unconscious accelerator operation. can do.

  In this case, as in claim 2, the current driving state parameter of the vehicle is detected or estimated by the driving state determination means, and the driving state parameter at which the vehicle is in a constant vehicle speed driving state is determined as the constant vehicle speed driving operation parameter calculation means. It is preferable to determine whether or not the vehicle is in a substantially constant speed driving state by comparing the current driving state parameter and the driving state parameter that is in a constant vehicle speed driving state. In this way, it is possible to accurately determine whether or not the vehicle is running at a substantially constant speed, and it is possible to improve the determination accuracy of the driver's unconscious accelerator operation based on the determination result.

  Specifically, as in claim 3, at least one of the current accelerator opening degree, throttle opening degree, and intake air amount is detected as a parameter of the current operating state, and the driving is performed in a constant vehicle speed state. As the state parameter, at least one of the accelerator opening, the throttle opening, and the intake air amount may be calculated based on the road surface gradient and the transmission gear stage. In this way, even if there is a situation in which the accelerator opening, throttle opening, intake air amount, etc. at which the vehicle travels at a constant vehicle speed changes depending on the road surface gradient or the gear position of the transmission, it is not affected by the situation. It is possible to accurately determine whether or not the vehicle is traveling at a constant speed. This makes it possible to accurately determine whether or not the vehicle is running at a substantially constant speed, not only on the flat ground, but also on the downhill where the driver's unconscious accelerator operation is likely to occur. Can be improved.

  Alternatively, the current axle torque is estimated based on the output torque of the internal combustion engine and the shift speed of the transmission as a parameter of the current operating state, and the operating state in which the vehicle is in a constant vehicle speed running state is provided. As a parameter, the axle torque may be calculated based on the road surface gradient. In this way, even if there is a situation in which the axle torque changes depending on the gear stage of the transmission and the axle torque that causes the vehicle to run at a constant vehicle speed due to the road gradient, the vehicle runs at a substantially constant speed without being affected by it. Whether or not it is in a state can be determined with high accuracy, and substantially the same effect as in the third aspect can be obtained.

  Further, as in claim 5, when the difference between the parameter of the current driving state and the parameter of the driving state that becomes the constant vehicle speed driving state is within a predetermined range for a predetermined time or longer, the substantially constant speed driving state is obtained. It is good to make a judgment. This prevents the hunting phenomenon in which the determination result frequently switches between the substantially constant speed driving state and the non-constant speed driving state when the current driving state is in the vicinity of the driving state where the constant vehicle speed driving state is reached. it can.

  Further, as in claim 6, vehicle speed variation determining means for determining whether or not the current vehicle speed variation (for example, vehicle acceleration) is within a predetermined range, and the current axle torque and the moving average of the axle torque At least one of torque determination means for determining whether or not the difference is within a predetermined range is provided, and the determination result of at least one of the vehicle speed variation determination means and the torque determination means is also taken into consideration in a substantially constant speed traveling state. You may make it determine whether there exists. In this way, it can be determined with higher accuracy whether or not the vehicle is running at a substantially constant speed.

  Further, the fuel cut prohibition is canceled by the fuel cut prohibition canceling means when the state where the accelerator operation is not performed during the fuel cut prohibition continues for a predetermined time or when the brake operation is performed. Anyway. In other words, it is determined that the driver has unconsciously operated the accelerator until the predetermined period has elapsed after switching from the substantially constant speed traveling state to the non-constant speed traveling state, but the fuel cut is prohibited. When the accelerator is not operated for a predetermined time or longer, the driver deliberately determines that the accelerator opening is kept constant and cancels the fuel cut prohibition state. Further, when there is a brake operation, it is determined that the driver has intentionally released the accelerator operation and operated the brake, and the fuel cut prohibition state is released. Thereby, if the fuel cut execution condition at the time of deceleration is satisfied, the fuel cut can be executed as usual to improve the fuel consumption.

  Further, as in claim 8, at least one of the accelerator opening, the output torque of the internal combustion engine, and the axle torque changes from a state of a predetermined value or more, and the determination result of the travel state determination means is from the substantially constant speed travel state. When switching to the non-constant speed running state, the fuel cut may be permitted by the fuel cut permission means. In other words, when the accelerator opening, the output torque of the internal combustion engine, or the axle torque changes from a predetermined value or more and switches from a substantially constant speed running state to a non-constant speed running state, the driver's conscious accelerator It is determined that the operation has switched from the substantially constant speed running state to the non-constant speed running state, and fuel cut is permitted (fuel cut is not prohibited). Thereby, if the fuel cut execution condition at the time of deceleration is satisfied, the fuel cut can be executed as usual to improve the fuel consumption.

  By the way, the influence of the fuel cut by the driver's unintentional accelerator operation on the drivability increases when the vehicle speed is low and the transmission gear is low.

  Therefore, as in claim 9, when the determination result of the traveling state determining means is switched from the substantially constant speed traveling state to the non-constant speed traveling state, the vehicle speed is a low vehicle speed below a predetermined value and / or the transmission gear stage. It is preferable that fuel cut is prohibited when the gear is a low gear position that is less than or equal to a predetermined gear position. In this way, the fuel cut can be prohibited only at low vehicle speeds and low gears, that is, only when the fuel cut by the driver's unintentional accelerator operation has a great influence on drivability. The prohibition of fuel cut can be avoided as described above, and deterioration of fuel consumption due to prohibition of fuel cut can be suppressed.

  Several embodiments embodying the best mode for carrying out the present invention will be described below.

A first embodiment of the present invention will be described with reference to FIGS.
First, a schematic configuration of the entire system will be described with reference to FIG.
The automatic transmission 11 is provided with a torque converter 12 and a hydraulically driven transmission gear mechanism 13. An input shaft 15 of the torque converter 12 is connected to an output shaft of the engine 14 which is an internal combustion engine, and a transmission gear mechanism 13 is connected to the output shaft 16 of the torque converter 12. Further, the torque converter 12 is provided with a hydraulically driven lockup clutch (hereinafter referred to as “L / U clutch”) 17 for engaging or disengaging between the input shaft 15 side and the output shaft 16 side. It has been.

  The output torque of the engine 14 is transmitted to the transmission gear mechanism 13 via the torque converter 12 and is shifted by a plurality of gears (such as planetary gears) of the transmission gear mechanism 13 to drive wheels 18 (front wheels or rear wheels) of the vehicle. Is transmitted to. The transmission gear mechanism 13 is provided with a plurality of clutches and brakes that are friction engagement elements for switching between a plurality of shift speeds, and the engagement / release of each clutch and each brake is switched hydraulically to transmit power. The gear ratio is switched by switching the combination of gears.

  Further, an alternator 19 (generator) and an air conditioner (air conditioner) compressor 20 are connected to the output shaft of the engine 14 via power transmission mechanisms (pulleys, belts, etc.), respectively. The compressor 20 is rotated by the power of the engine 14.

  On the other hand, an electronic control circuit (hereinafter referred to as “ECU”) 21 is composed of one or a plurality of microcomputers that comprehensively control the engine 14 and the automatic transmission 11, and various engine control programs (see FIG. (Not shown) is executed to control the throttle opening, ignition timing, and fuel injection amount in accordance with the operating state, and various shift control programs (not shown) are executed to thereby produce a shift lever (not shown). The transmission gear mechanism 13 and the L / U clutch 17 are controlled according to the operation range and the operating state.

  Specifically, the target axle torque setting unit 22 calculates the target axle torque based on the vehicle speed, the accelerator opening, and the like, and the power train manager unit 23 calculates the target axle torque, the operating state of the engine 14, the automatic transmission 11 ( Based on the operating state of the transmission gear mechanism 13 and the L / U clutch 17), the target engine torque, the target gear stage, the L / U (lockup) execution request, and the like are calculated.

  Thereafter, the engine torque control unit 24 calculates the throttle opening, ignition timing, fuel injection amount, and the like based on the target engine torque. The L / U clutch control unit 25 calculates the control hydraulic pressure of the L / U clutch 17 based on the L / U execution request, and the shift control unit 26 calculates the clutches of the transmission gear mechanism 13 based on the target shift stage. And the control hydraulic pressure of each brake is calculated.

  In addition, when the predetermined deceleration fuel cut execution condition is satisfied (for example, when the accelerator opening is equal to or smaller than a predetermined value and the engine rotational speed is in a region equal to or higher than the fuel cut return rotational speed), the ECU 21 A fuel cut to stop the injection is executed to improve fuel efficiency.

  However, when the driver keeps the amount of depression of the accelerator pedal constant and the vehicle is traveling at a constant vehicle speed, the driver may unintentionally move the accelerator pedal little by little. If the driver's unconscious accelerator operation repeats the establishment and non-establishment of the fuel cut execution condition during deceleration and repeats the fuel cut execution and return, the output torque of the engine 14 fluctuates and the drivability deteriorates. there is a possibility.

Therefore, the ECU 21 executes the routines shown in FIGS. 2 and 3 to be described later, thereby detecting the current accelerator opening, and traveling at a constant vehicle speed based on the gear stage, road gradient, and vehicle speed of the automatic transmission 11. Calculate the accelerator opening that will be in the state, and compare the current accelerator opening and the accelerator opening that will be in the constant vehicle speed running state, the vehicle speed is in a substantially constant speed driving state that is substantially constant or the vehicle speed is not substantially constant It is determined whether the vehicle is traveling at a non-constant speed. It is determined that the driver has switched to the non-constant speed running state by the driver's unconscious accelerator operation until the predetermined time has elapsed after the judgment result is switched from the substantially constant speed running state to the non-constant speed running state. Is prohibited. This prevents the fuel cut from being executed even when the fuel cut execution condition during deceleration is satisfied by switching from the substantially constant speed running state to the decelerating running state by the driver's unconscious accelerator operation during the substantially constant speed running. .
Hereinafter, the processing content of each routine of FIG.2 and FIG.3 which ECU21 performs is demonstrated.

[Running state determination routine]
The running state determination routine shown in FIG. 2 is repeatedly executed at a predetermined cycle while the ECU 21 is turned on, and serves as a running state determination unit in the claims. When this routine is started, first, in step 101, parameters (accelerator opening degree, vehicle speed, gear position of the automatic transmission 11, road surface gradient, etc.) of the current driving state of the vehicle are determined based on the outputs of various sensors. measure. Here, the road surface gradient detection method is, for example, based on an output signal of a sensor whose output changes according to a road surface gradient (an inclination angle of the vehicle) such as an inclination sensor or an acceleration sensor mounted on a vehicle. It may be detected. Alternatively, the road surface gradient may be estimated based on the driving state of the vehicle (for example, the relationship between the required power and the vehicle speed), or the road surface gradient may be acquired from the road information searched by the car navigation system.

  Thereafter, the process proceeds to step 102, and after reading the current accelerator opening Thrnow, the process proceeds to step 103, where the current accelerator opening Thrnow is subjected to a hysteresis process to obtain the current accelerator opening Thrnowhys after the hysteresis process. In this hysteresis processing, for example, when the difference between the current value of the accelerator opening and the previous value is equal to or smaller than a predetermined value, the influence of noise is removed by setting the same value as the previous value as the current value. Alternatively, the detected value of the accelerator opening may be smoothed. The processing in these steps 102 and 103 serves as an operating state determination means in the claims.

  Thereafter, the process proceeds to step 104, and a constant vehicle speed running state corresponding to the current gear position, road gradient and vehicle speed of the automatic transmission 11 is referred to with reference to the map of the accelerator opening Thrrl in which the vehicle is running at a constant vehicle speed in FIG. The accelerator opening Thrrl is calculated. The map shown in FIG. 4 is created in advance based on experimental data, design data, etc., and stored in the ROM of the ECU 21, and is in a constant vehicle speed running state with the road surface gradient and the vehicle speed as parameters for each gear position of the automatic transmission 11. The accelerator opening degree Thrrl is set.

  Thereafter, the process proceeds to step 105, where hysteresis processing is performed on the accelerator opening Thrrl at which the vehicle travels at a constant vehicle speed, and the accelerator opening Thrrlhys at which the vehicle travels at a constant vehicle speed after the hysteresis processing is obtained. The processing of these steps 104 and 105 serves as a constant vehicle speed travel operation parameter calculation means in the claims.

  Thereafter, the routine proceeds to step 106, where it is determined whether or not the difference between the current accelerator opening degree Thrnowhys and the accelerator opening degree Thrrlhys at which the vehicle travels at a constant vehicle speed is within a predetermined range (| Thrnowhys−Thrrlhys | ≦ determination value). .

  If it is determined in step 106 that the difference between the current accelerator opening degree Thrnowhys and the accelerator opening degree Thrrlhys at which the vehicle travels at a constant vehicle speed is within a predetermined range, the process proceeds to step 107 and the current accelerator opening degree Thrnowhys is reached. And the accelerator opening degree Thrlrlhys in which the vehicle travels at a constant vehicle speed is determined whether or not the state within the predetermined range has continued for a predetermined time or more. It is determined that the vehicle is running at a constant speed.

  On the other hand, if it is determined in step 106 that the difference between the current accelerator opening degree Thrnowhys and the accelerator opening degree Thrrlhys in which the vehicle travels at a constant vehicle speed is not within a predetermined range, or in step 107, the current accelerator opening degree Thrnowhys. When it is determined that the state where the difference between the accelerator opening degree Thrrlhys and the constant vehicle speed traveling state is within the predetermined range has not been continued for a predetermined time or longer, the routine proceeds to step 109, where the non-constant speed traveling state (substantially) It is determined that the vehicle is not running at a constant speed.

[Fuel cut prohibition / permission judgment routine]
The fuel cut prohibition / permission determination routine shown in FIG. 3 is repeatedly executed at a predetermined cycle while the ECU 21 is powered on. When this routine is started, first, at step 201, it is determined based on the determination result of the above-described traveling state determination routine of FIG. If it is determined, the routine is terminated without performing the processing from step 202 onward.

  On the other hand, if it is determined in step 201 that the vehicle is in the non-constant speed running state (not the substantially constant speed running state), the process proceeds to step 202 to switch from the substantially constant speed running state to the non-constant speed running state. If it is determined that it is immediately after switching from the substantially constant speed running state to the non-constant speed running state, the process proceeds to step 203 and the non-constant speed running state is reached from the substantially constant speed running state. The count value of the timer that measures the elapsed time after switching to the state is set to a predetermined value.

  After the timer count value is set to a predetermined value in step 203, the process proceeds from step 202 to step 204. After the timer count value is counted down, the process proceeds to step 205, where the timer count value has reached 0. It is determined whether or not a predetermined time has elapsed since switching to the non-constant speed running state.

  If it is determined in step 205 that the predetermined time has not yet elapsed since switching to the non-constant speed running state, the process proceeds to step 206 to determine whether or not there is a brake operation. If it is determined that there is not, the process proceeds to step 207, where it is determined that the vehicle is switched from the substantially constant speed traveling state to the non-constant speed traveling state by the driver's unconscious accelerator operation, and then the process proceeds to step 208 and fuel cut is prohibited. The processing in step 208 serves as fuel cut prohibiting means in the claims.

  This prevents the fuel cut from being executed even when the fuel cut execution condition during deceleration is satisfied by switching from the substantially constant speed running state to the decelerating running state by the driver's unconscious accelerator operation during the substantially constant speed running. .

  Thereafter, when it is determined in step 205 that a predetermined time has elapsed since switching to the non-constant speed running state (that is, when the non-constant speed running state continues for a predetermined time or more), the driver's consciousness If it is determined that there is a high possibility that the vehicle is maintained in the non-constant speed running state by an accelerator operation, the routine proceeds to step 209, where the fuel cut prohibition state is canceled and the fuel cut is permitted. Thereafter, if the deceleration fuel cut execution condition is satisfied, the fuel cut is executed as usual.

  If the state where there is no accelerator operation for a predetermined time or longer while fuel cut is prohibited continues, it is determined that the driver consciously holds the accelerator opening constant, and the routine proceeds to step 209, where fuel cut is performed. It is also possible to cancel the prohibition state and allow fuel cut.

  If it is determined in step 206 that there is a brake operation, it is determined that the driver has intentionally released the accelerator operation and operated the brake, and the process proceeds to step 209 to prohibit the fuel cut. Is released to allow fuel cut. The processing in step 209 serves as fuel cut prohibition canceling means in the claims.

  In the first embodiment described above, it is determined whether the traveling state of the vehicle is a substantially constant speed traveling state or a non-constant speed traveling state, and the determination result is changed from the substantially constant speed traveling state to the non-constant speed traveling state. Until the predetermined time has elapsed since switching, the driver was judged to have switched to the non-constant speed running state by unintentional accelerator operation and the fuel cut was prohibited. The fuel cut can be prevented from being executed even when the fuel cut execution condition at the time of deceleration is satisfied by switching from the substantially constant speed running state to the decelerating running state by the unconscious accelerator operation. This makes it possible to avoid repeated execution of fuel cut and return due to the driver's unintentional accelerator operation while driving at a substantially constant speed, thereby preventing deterioration of drivability due to the driver's unconscious accelerator operation. can do.

  Further, in the first embodiment, the current accelerator opening is detected, and on the basis of the shift stage, the road surface gradient, and the vehicle speed of the automatic transmission 11, the accelerator opening at which the vehicle travels at a constant vehicle speed is calculated using a map. Since the current accelerator opening is compared with the accelerator opening at which the vehicle travels at a constant vehicle speed, it is determined whether or not the vehicle is in a substantially constant speed traveling state. Therefore, the shift stage, road gradient, and vehicle speed of the automatic transmission 11 are determined. Even if there is a situation in which the accelerator opening degree at which the vehicle travels at a constant vehicle speed changes, it is possible to accurately determine whether or not the vehicle is traveling at a substantially constant speed without being affected by this. As a result, it is possible to accurately determine whether or not the vehicle is traveling at a substantially constant speed not only on the flat ground but also on a downhill where the driver's unconscious accelerator operation is likely to occur, and the driver's unconsciousness based on the determination result. The determination accuracy of the accelerator operation can be improved.

  Further, in the first embodiment, when the difference between the current accelerator opening and the accelerator opening at which the vehicle travels at a constant vehicle speed is within a predetermined range, it is determined that the vehicle is in a substantially constant speed traveling state. Therefore, when the current accelerator opening is in the vicinity of the accelerator opening at which the vehicle is traveling at a constant vehicle speed, the determination result of the driving state is frequently switched between a substantially constant speed driving state and a non-constant speed driving state. The hunting phenomenon that changes can be prevented.

  Further, in the first embodiment, it is determined that the driver's unconscious accelerator operation is performed until a predetermined time has elapsed after switching from the substantially constant speed traveling state to the non-constant speed traveling state, but fuel cut is prohibited. If there is no accelerator operation for a predetermined time or longer while fuel cut is prohibited, the driver deliberately determines that the accelerator opening is held constant and cancels the fuel cut prohibition state. In addition, when there is a brake operation, the driver deliberately releases the accelerator operation and determines that the brake has been operated, and the fuel cut prohibition state is released. If the execution condition is satisfied, the fuel cut can be executed as usual to improve the fuel consumption.

  In the first embodiment, the current accelerator opening is compared with the accelerator opening at which the vehicle travels at a constant vehicle speed to determine whether or not the vehicle is in a substantially constant speed traveling state. However, the present invention is not limited to this. First, for example, the current throttle opening is compared with the throttle opening at which the vehicle is running at a constant vehicle speed to determine whether or not the vehicle is running at a substantially constant speed, or the current intake air amount is It may be determined whether or not the vehicle is in a substantially constant speed traveling state by comparing the amount of intake air that is in a constant vehicle speed traveling state.

  Next, Embodiment 2 of the present invention will be described with reference to FIGS. However, description of substantially the same parts as those in the first embodiment will be omitted or simplified, and different parts from the first embodiment will be mainly described.

  In the second embodiment, the ECU 21 executes a running state determination routine shown in FIG. 5 to be described later, so that the current axle torque is based on the current engine torque (the output torque of the engine 14), the gear position of the automatic transmission 11, and the like. (Torque transmitted to the drive wheel 18) is estimated, and the axle torque at which the vehicle travels at a constant vehicle speed is calculated based on the road surface gradient and the vehicle speed, and the current axle torque and the axle torque at which the vehicle travels at a constant vehicle speed are calculated. In comparison, it is determined whether or not the vehicle is running at a substantially constant speed.

  Hereinafter, the processing content of the traveling state determination routine shown in FIG. 5 will be described. In this routine, first, in step 301, parameters of the current operating state of the vehicle (engine speed, fuel injection amount, ignition timing retardation amount, vehicle speed, shift stage of the automatic transmission 11) based on outputs of various sensors and the like. , Road slope, etc.).

  Thereafter, the routine proceeds to step 302, where the current engine torque Tenow is estimated (calculated) based on the current engine speed, fuel injection amount, ignition timing retardation amount (retard amount), etc., and then the routine proceeds to step 303. The current axle torque Tvnow is estimated (calculated) based on the engine torque Tenow, the gear stage (speed ratio) of the automatic transmission 11, the torque transmission efficiency of the torque converter 12, and the like. At this time, if the axle torque Tvnow is set in consideration of the operating state of the auxiliary equipment (for example, the alternator 19, the air conditioner compressor 20, the hydraulic pump for power steering, etc.), the estimation accuracy of the axle torque Tvnow is improved. be able to.

  Thereafter, the process proceeds to step 304, where the current axle torque Tvnow is subjected to hysteresis processing to obtain the current axle torque Tvnowhys after the hysteresis processing. The processing of these steps 302 to 304 serves as operating state determination means in the claims.

  Thereafter, the routine proceeds to step 305, where the axle torque Tvrl for the constant vehicle speed traveling state corresponding to the current road gradient and the vehicle speed is calculated with reference to the map of the axle torque Tvrl for the constant vehicle speed traveling state in FIG. The map shown in FIG. 6 is created in advance based on experimental data, design data, etc., and stored in the ROM of the ECU 21, and axle torque Tvrl for setting a constant vehicle speed traveling state is set using road surface gradient and vehicle speed as parameters.

  Thereafter, the process proceeds to step 306, where the hysteresis torque is applied to the axle torque Tvrl that is in the constant vehicle speed running state to obtain the axle torque Tvrlhys that is in the constant vehicle speed running state after the hysteresis processing. The processing of these steps 305 and 306 plays a role as constant vehicle speed traveling operation parameter calculation means in the claims.

  Thereafter, the process proceeds to step 307, where it is determined whether or not the difference between the current axle torque Tvnowhys and the axle torque Tvrlhys at which the vehicle travels at a constant vehicle speed is within a predetermined range (| Tvnowhys−Tvrlhys | ≦ determination value).

  If it is determined in step 307 that the difference between the current axle torque Tvnowhys and the axle torque Tvrlhys at which the vehicle travels at a constant vehicle speed is within a predetermined range, the process proceeds to step 308, where the current axle torque Tvnowhys and the constant vehicle speed are It is determined whether or not the state where the difference from the axle torque Tvrlhys that is in the traveling state is within a predetermined range continues for a predetermined time or more. It is determined that

  On the other hand, if it is determined in step 307 that the difference between the current axle torque Tvnowhys and the axle torque Tvrlhys in which the vehicle runs at a constant speed is not within a predetermined range, or in step 308, the current axle torque Tvnowhys and the constant vehicle speed are If it is determined that the state in which the difference from the axle torque Tvrlhys in the traveling state is within the predetermined range does not continue for a predetermined time or longer, the process proceeds to step 310, where the non-constant speed traveling state (substantially constant speed traveling state) Is not).

  In the second embodiment described above, the current axle torque is estimated based on the current engine torque, the shift stage of the automatic transmission 11, and the like, and the axle torque that becomes a constant vehicle speed running state based on the road surface gradient and the vehicle speed. And the current axle torque is compared with the axle torque at which the vehicle travels at a constant vehicle speed to determine whether or not the vehicle is in a substantially constant speed travel state. Even when there is a situation where the torque changes and the axle torque that changes to a constant vehicle speed depending on the road surface gradient and vehicle speed, it is possible to accurately determine whether or not the vehicle is in a substantially constant speed driving state without being affected by it. And substantially the same effects as those of the first embodiment can be obtained.

  Next, Embodiment 3 of the present invention will be described with reference to FIGS. However, description of substantially the same parts as those of the second embodiment will be omitted or simplified, and different parts from the second embodiment will be mainly described.

  In the third embodiment, the ECU 21 executes a running state determination routine shown in FIGS. 7 and 8 to be described later, thereby estimating the current axle torque and calculating the axle torque that is in a constant vehicle speed running state. The difference between the vehicle axle torque and the moving average of the axle torque is calculated, and the current vehicle acceleration is calculated as information on the current vehicle speed fluctuation. Then, comprehensively evaluate the difference between the current axle torque and the axle torque that causes the vehicle to travel at a constant speed, the difference between the current axle torque and its moving average, and the current vehicle acceleration (variation in vehicle speed). It is determined whether or not the vehicle is running at a substantially constant speed. Here, the moving average may be an arithmetic average of the most recent predetermined number of data (simple moving average), or may be averaged by assigning different weights to the most recent predetermined number of data (weighted moving average). ).

  Hereinafter, processing contents of the traveling state determination routine of FIGS. 7 and 8 will be described. In this routine, first, in step 401, parameters of the current operating state of the vehicle (engine speed, fuel injection amount, ignition timing retardation amount, vehicle speed, shift stage of the automatic transmission 11) based on outputs of various sensors and the like. , Road slope, etc.).

  Thereafter, the current axle torque Tvnow is estimated (calculated) based on the current engine torque Tenow and the shift speed of the automatic transmission 11, and the current axle torque Tvnow is subjected to hysteresis processing to obtain the current current state after the hysteresis processing. The axle torque Tvnowhys is calculated (steps 402 to 404).

  Thereafter, after calculating the axle torque Tvrl that is in a constant vehicle speed traveling state according to the road surface gradient and the vehicle speed, the axle torque Tvrl that is in the constant vehicle speed traveling state is subjected to hysteresis processing, and the constant vehicle speed traveling state after the hysteresis processing is determined. The following axle torque Tvrlhys is obtained (steps 405 and 406).

  Thereafter, the process proceeds to step 407, and after calculating the moving average Tvave of the axle torque Tvnow (the average value of the data of the axle torque Tvnow from the predetermined number of detection times to the current time), the process proceeds to step 408, where the current axle torque Tvnow and its current torque A difference Dtv from the moving average Tvave is calculated.

  Thereafter, the process proceeds to step 409, where the current vehicle acceleration Gv (the differential value of the vehicle speed or the amount of change in the vehicle speed per unit time) is calculated, and then the process proceeds to step 410, where the current vehicle acceleration Gv is subjected to an annealing process. The current vehicle acceleration Gvave after the annealing process is obtained.

Thereafter, in steps 411 to 414 in FIG. 8, whether or not the vehicle is running at a substantially constant speed is determined, for example, according to the following conditions (1) to (4).
(1) The difference between the current axle torque Tvnowhys and the axle torque Tvrlhys at which the vehicle travels at a constant vehicle speed is within a predetermined range (| Tvnowhys −Tvrlhys | ≦ judgment value) [step 411].
(2) The difference Dtv between the current axle torque Tvnow and the moving average Tvave is within a predetermined range (| Dtv | ≦ determination value) [Step 412]
(3) The current vehicle acceleration Gvave is within a predetermined range (| Gvave | ≦ judgment value) [step 413].
(4) A state where all of the above conditions (1) to (3) are satisfied continues for a predetermined time or more [Step 414].

If it is determined that all of the above conditions (1) to (4) are satisfied, the process proceeds to step 415, where it is determined that the vehicle is running at a substantially constant speed.
On the other hand, if it is determined that any one of the above conditions (1) to (4) is not satisfied, the routine proceeds to step 416, where the vehicle is in a non-constant speed traveling state (substantially constant speed traveling state). Is not).

  In this case, the process of step 412 serves as a torque determination means in the claims, and the process of step 413 serves as a vehicle speed fluctuation determination means in the claims.

  In the third embodiment described above, a comprehensive evaluation is made of the difference between the current axle torque and the axle torque at a constant vehicle speed, the difference between the current axle torque and its moving average, and the current vehicle acceleration. Thus, since it is determined whether or not the vehicle is in a substantially constant speed running state, it is possible to further accurately determine whether or not the vehicle is in a substantially constant speed running state.

  In the third embodiment, the difference between the current axle torque and the axle torque at a constant vehicle speed, the difference between the current axle torque and its moving average, and the current vehicle acceleration are within a predetermined range. However, the present invention is not limited to this. For example, the difference between the current axle torque and the axle torque at which the vehicle runs at a constant speed, the current axle torque, and the When two or one of the difference from the moving average and the current vehicle acceleration are within a predetermined range, it may be determined that the vehicle is running at a substantially constant speed.

  Next, Embodiment 4 of the present invention will be described with reference to FIG. However, description of substantially the same parts as those in the first embodiment will be omitted or simplified, and different parts from the first embodiment will be mainly described.

  In the fourth embodiment, the ECU 21 executes a fuel cut prohibition / permission determination routine shown in FIG. 9 to be described later, whereby the accelerator opening degree and the axle torque are changed from a state of a predetermined value or more, and the vehicle is indeterminate from the substantially constant speed running state. When the vehicle is switched to the high-speed driving state, it is determined that the vehicle is switched from the substantially constant speed driving state to the non-constant speed driving state by the driver's conscious accelerator operation, and the fuel cut is permitted.

  Hereinafter, the processing content of the fuel cut prohibition / permission determination routine of FIG. 9 will be described. The routine of FIG. 9 is obtained by adding the processing of steps 201a and 206a to the routine of FIG. 3 described in the first embodiment, and the processing of each other step is the same as that of FIG.

  In the fuel cut prohibition / permission determination routine of FIG. 9, if it is determined at step 201 that the vehicle is running at a substantially constant speed, the routine proceeds to step 201a, where the accelerator opening Apmem and the axle torque Tvmem are stored during the substantially constant speed running. To do.

  After that, if it is determined in step 201 that the vehicle is traveling at a non-constant speed, the timer count value is set to a predetermined value, the timer count value is counted down, and the timer count value reaches zero. It is determined whether or not a predetermined time has elapsed since switching to the non-constant speed running state depending on whether or not (steps 202 to 205).

  If it is determined in step 205 that the predetermined time has not yet elapsed since switching to the non-constant speed running state, the process proceeds to step 206 to determine whether or not there is a brake operation, and there is no brake operation. If it is determined, the routine proceeds to step 206a, where it is determined whether or not the accelerator opening Apmem and the axle torque Tvmem stored during the substantially constant speed traveling are respectively greater than or equal to a predetermined value.

  In this step 206a, when it is determined that both the accelerator opening Apmem and the axle torque Tvmem stored during the substantially constant speed travel are greater than or equal to a predetermined value, that is, both the accelerator opening and the axle torque are respectively predetermined. When the state changes from the above value to the non-constant speed driving state, the driver switches to the non-constant speed driving state from the substantially constant speed driving state by the driver's conscious accelerator operation. If it is determined that the fuel has been cut, the process proceeds to step 209 to permit fuel cut. The processing in step 209 serves as fuel cut permission means in the claims. Thereafter, if the deceleration fuel cut execution condition is satisfied, the fuel cut is executed as usual.

  On the other hand, if it is determined in step 206a that one or both of the accelerator opening Apmem and the axle torque Tvmem stored during the substantially constant speed travel is smaller than a predetermined value, the routine proceeds to step 207, where the driver is unconscious. After determining that the vehicle is switched from the substantially constant speed traveling state to the non-constant speed traveling state by a simple accelerator operation, the routine proceeds to step 208, and fuel cut is prohibited.

  In the fourth embodiment described above, when both the accelerator opening and the axle torque change from a state of a predetermined value or more and switch from a substantially constant speed running state to a non-constant speed running state, the driver's awareness The fuel cut is permitted because it is determined that the vehicle has been switched from the substantially constant speed running state to the non-constant speed running state by a typical accelerator operation, so if the fuel cut execution condition during deceleration is satisfied, the fuel cut is performed as usual. To improve fuel efficiency.

  In the fourth embodiment, the fuel cut is permitted when both the accelerator opening and the axle torque are changed from a state of a predetermined value or more to switch from the substantially constant speed traveling state to the non-constant speed traveling state. However, when one of the accelerator opening degree and the axle torque changes from a state of a predetermined value or more and changes from the substantially constant speed traveling state to the non-constant speed traveling state, the fuel cut is permitted. good. Further, engine torque may be used instead of axle torque.

  Next, Embodiment 5 of the present invention will be described with reference to FIG. However, description of substantially the same parts as those in the fourth embodiment will be omitted or simplified, and different parts from the fourth embodiment will be mainly described.

  The influence of fuel cut by unintentional accelerator operation by the driver on drivability increases because of the low vehicle speed where the vehicle speed is low and the low gear stage where the speed of the automatic transmission 11 is low (for example, 1st speed, 2nd speed, etc.). Is the case.

  Thus, in the fifth embodiment, the ECU 21 executes a fuel cut prohibition / permission determination routine shown in FIG. 10 described later, so that the vehicle speed is less than or equal to a predetermined value when the substantially constant speed traveling state is switched to the non-constant speed traveling state. The fuel cut is prohibited when the low vehicle speed or the shift stage of the automatic transmission 11 is a low shift stage that is a predetermined speed or less.

  Hereinafter, the processing content of the fuel cut prohibition / permission determination routine of FIG. 10 will be described. The routine of FIG. 10 is obtained by adding the process of step 207a to the routine of FIG. 9 described in the fourth embodiment, and the processes of other steps are the same as those of FIG.

  In the fuel cut prohibition / permission determination routine of FIG. 10, when it is determined in step 201 that the vehicle is in the non-constant speed running state, the timer count value is set to a predetermined value, and then the timer count value is counted down. Depending on whether or not the count value of the timer has reached 0, it is determined whether or not a predetermined time has elapsed since switching to the non-constant speed running state (steps 202 to 205).

  If it is determined in step 205 that the predetermined time has not yet elapsed since switching to the non-constant speed running state, the process proceeds to step 206 to determine whether or not there is a brake operation, and there is no brake operation. If it is determined, the routine proceeds to step 206a, where it is determined whether or not the accelerator opening Apmem and the axle torque Tvmem stored during the substantially constant speed traveling are respectively greater than or equal to a predetermined value.

  If it is determined in step 206a that one or both of the accelerator opening Apmem and the axle torque Tvmem stored during the substantially constant speed travel are smaller than a predetermined value, the process proceeds to step 207, where the driver is unconscious. After determining that the vehicle is switched from the substantially constant speed running state to the non-constant speed running state by the accelerator operation, the process proceeds to step 207a, where the vehicle speed is a low vehicle speed below a predetermined value or the automatic transmission 11 is a low gear speed where the gear stage is below a predetermined speed. It is determined whether it is a stage (for example, 1st speed, 2nd speed, etc.).

  If it is determined in step 207a that the vehicle is at a low vehicle speed or a low gear position, it is determined that the influence on drivability is large when the fuel cut is executed by the driver's unconscious accelerator operation. Proceeding to 208, fuel cut is prohibited.

  On the other hand, if it is determined in step 207a that neither the low vehicle speed nor the low gear is determined, the influence on the drivability is not a problem even if the fuel cut is executed by the driver's unconscious accelerator operation. It proceeds to step 209 and permits fuel cut.

  In the fourth embodiment described above, when the vehicle is switched from the substantially constant speed running state to the non-constant speed running state, the fuel cut is executed in the case of the low vehicle speed or the low gear position, that is, the driver's unconscious accelerator operation. In this case, the fuel cut is prohibited only when it is judged that the influence on drivability is large. Therefore, avoiding prohibiting the fuel cut more than necessary and deteriorating the fuel consumption by prohibiting the fuel cut. Can be suppressed.

  In the fifth embodiment, the fuel cut is prohibited when it is determined that the vehicle speed is low or the gear position is low. However, when it is determined that the vehicle speed is low and the gear speed is low, the fuel cut is performed. May be prohibited.

  In the first to fifth embodiments, the difference between the current driving state (accelerator opening and axle torque) and the driving state (accelerator opening and axle torque) in which the vehicle is running at a constant vehicle speed is within a predetermined range. Although it is determined that the vehicle is running at a substantially constant speed when it continues for a predetermined time or more, the present invention is not limited to this, and the ratio between the current driving state and the driving state in which the vehicle runs at a constant vehicle speed is within a predetermined range. May be determined to be in a substantially constant speed traveling state when is continued for a predetermined time or longer. Alternatively, when the difference or ratio between the current driving state and the driving state in which the vehicle is traveling at a constant vehicle speed falls within a predetermined range, it may be determined that the driving state is substantially constant.

  Further, in each of the first to fifth embodiments, the fuel cut is prohibited until a predetermined time elapses after switching from the substantially constant speed running state to the non-constant speed running state. After switching from the constant speed traveling state to the non-constant speed traveling state, for example, the fuel cut may be prohibited until the number of fuel injections, the number of ignitions, the travel distance, etc. reach a predetermined value.

  Further, in each of the first to fifth embodiments, the fuel cut is prohibited when switching from the substantially constant speed traveling state to the non-constant speed traveling state (decelerated traveling state or accelerated traveling state). The fuel cut may be prohibited only when the traveling state is switched to the decelerating traveling state.

It is a schematic block diagram of the whole system in Example 1 of this invention. 6 is a flowchart illustrating a process flow of a traveling state determination routine according to the first embodiment. 6 is a flowchart illustrating a flow of processing of a fuel cut prohibition / permission determination routine according to the first embodiment. It is a figure which shows notionally an example of the map of the throttle opening Thrrl used as the constant vehicle speed driving state of Example 1. FIG. 6 is a flowchart showing a flow of processing of a traveling state determination routine of Example 2. It is a figure which shows notionally an example of the map of the axle torque Tvrl used as the constant vehicle speed driving state of Example 2. FIG. 12 is a flowchart (No. 1) illustrating a flow of processing of a traveling state determination routine according to the third embodiment. 12 is a flowchart (part 2) illustrating a flow of processing of a traveling state determination routine according to the third embodiment. 12 is a flowchart showing a flow of processing of a fuel cut prohibition / permission determination routine according to a fourth embodiment. 10 is a flowchart showing a flow of processing of a fuel cut prohibition / permission determination routine according to a fifth embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Automatic transmission, 12 ... Torque converter, 13 ... Transmission gear mechanism, 14 ... Engine (internal combustion engine), 21 ... ECU (running state judging means, fuel cut prohibiting means, driving state judging means, constant vehicle speed running operation parameter calculation Means, vehicle speed variation determination means, torque determination means, fuel cut prohibition release means, fuel cut permission means)

Claims (9)

In a control device for an internal combustion engine having a function of executing fuel cut to stop fuel injection of the internal combustion engine when a predetermined deceleration fuel cut execution condition is satisfied,
Traveling state determination means for determining whether the vehicle traveling state is a substantially constant speed traveling state in which the vehicle speed is substantially constant;
Until the predetermined period elapses after the determination result of the driving state determination means is changed from the substantially constant speed driving state to the non-constant speed driving state where the vehicle speed is not substantially constant, the non-deterministic operation is performed by the driver's unconscious accelerator operation. A control device for an internal combustion engine, comprising: a fuel cut prohibiting unit that determines that the vehicle has switched to a high speed running state and prohibits the fuel cut. Driving state determination means for detecting or estimating a parameter of the current driving state of the vehicle;
A constant vehicle speed travel operation parameter calculation means for calculating a parameter of an operation state in which the vehicle is in a constant vehicle speed travel state,
The traveling state determination means determines whether or not the vehicle is in the substantially constant speed traveling state by comparing the parameter of the current driving state with the parameter of the driving state that becomes the constant vehicle speed traveling state. The control apparatus for an internal combustion engine according to claim 1. The operating state determination means detects at least one of a current accelerator opening, a throttle opening, and an intake air amount as a parameter of the current operating state,
The constant vehicle speed driving operation parameter calculating means calculates at least one of an accelerator opening, a throttle opening, and an intake air amount as a parameter of an operation state that becomes the constant vehicle speed driving state, a road surface gradient, a transmission gear stage, The control device for an internal combustion engine according to claim 2, wherein the control device calculates based on the above. The driving state determination means estimates the current axle torque as a parameter of the current driving state based on an output torque of the internal combustion engine and a transmission gear;
3. The control device for an internal combustion engine according to claim 2, wherein the constant vehicle speed travel operation parameter calculation means calculates an axle torque based on a road surface gradient as a parameter of an operation state in which the constant vehicle speed travel state is achieved.   The traveling state determination means is configured to determine whether the current driving state parameter and the driving state parameter that becomes the constant vehicle speed traveling state are in the substantially constant speed traveling state when a state within a predetermined range continues for a predetermined time or longer. The control device for an internal combustion engine according to any one of claims 2 to 4, wherein the control device is determined to be present. Torque for determining whether or not the difference between the current axle torque and the moving average of the axle torque is within the predetermined range, and the vehicle speed fluctuation determining means for determining whether or not the current fluctuation in the vehicle speed is within the predetermined range. Comprising at least one of determination means;
The traveling state determination unit determines whether or not the vehicle is in the substantially constant speed traveling state in consideration of a determination result of at least one of the vehicle speed variation determination unit and the torque determination unit. The control apparatus for an internal combustion engine according to any one of 2 to 5.   Fuel cut prohibition canceling means for canceling the fuel cut prohibition state when the fuel cut prohibition unit prohibits the accelerator operation and the state where there is no accelerator operation continues for a predetermined time or more or when the brake operation is performed. The control device for an internal combustion engine according to claim 1, wherein the control device is an internal combustion engine.   At least one of the accelerator opening, the output torque of the internal combustion engine, and the axle torque changes from a state of a predetermined value or more, and the determination result of the travel state determination means changes from the substantially constant speed travel state to the non-constant speed travel state. The control apparatus for an internal combustion engine according to any one of claims 1 to 7, further comprising fuel cut permission means for permitting the fuel cut when switched.   The fuel cut prohibiting unit is configured to reduce the vehicle speed when the determination result of the traveling state determination unit is switched from the substantially constant speed traveling state to the non-constant speed traveling state and / or a shift of the transmission. The control apparatus for an internal combustion engine according to any one of claims 1 to 8, wherein the fuel cut is prohibited when the speed is a low gear position that is a predetermined speed or less.

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