JP2015117662A - Control method of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control method of an engine which can protect the engine while obtaining a favorable gear change feeling at a down-shift of a vehicle.SOLUTION: A control method which increases an engine output for improving a gear change feeling at a down-shift detects a down-grade and an engine rotation number, calculates an engine rotation number change rate, prohibits control for increasing the engine output when numerical values of the detection and the calculation exceed preset thresholds, and thereby suppresses that the engine exceeds allowable rotation.

Description

  The present invention relates to control of a vehicle including an engine and a transmission, and more particularly to an internal combustion engine control method for increasing engine output during downshifting.

  Conventionally, a manual transmission is connected to an engine via a clutch, and a clutch operation and a shift operation are performed by a driver. In recent years, transmissions have been developed in which an actuator is connected to a conventional manual transmission to automate the clutch operation and the shift operation. In a vehicle equipped with such a transmission, it is possible to drive lightly and with a direct feeling unique to a manual transmission vehicle, while reducing the burden of the shifting operation of the driver.

  In planetary gear type stepped automatic transmissions and belt type continuously variable automatic transmissions that are connected to the engine via a torque converter, gears are changed according to the operation of the driver's shift lever and the like. Some are set to manual mode.

  Japanese Patent Laying-Open No. 2006-258125 (Patent Document 1) discloses a control device for a transmission capable of performing a shift while maintaining the engine speed in a high rotation range. A control device disclosed in JP 2006-258125 A controls a transmission mounted on a vehicle. The control device does not permit the downshift request when the means for detecting the downshift request of the transmission by the operation of the driver and the rotational speed of the internal combustion engine is equal to or higher than a predetermined downshift permission rotational speed. Control means for controlling the transmission as described above, and changing means for changing the downshift permission rotational speed to increase when the degree of deceleration of the vehicle is large.

  According to the control device disclosed in Japanese Patent Application Laid-Open No. 2006-258125, when the degree of deceleration of the vehicle is large, the rotational speed of the internal combustion engine is reduced even during the downshift. For this reason, if the downshift is permitted only after the downshift permission rotational speed has been reduced, the rotational speed of the internal combustion engine has decreased too much during the downshift, and the rotational speed of the internal combustion engine after the downshift has changed. It is too low from the allowable rotational speed of the internal combustion engine. For this reason, when the degree of deceleration of the vehicle is large, the downshift permission rotation speed is increased in consideration of the rotation speed of the internal combustion engine that decreases during the shift time, and the downshift shift is advanced and the downshift speed is reduced. When the shift shift is completed, the allowable rotational speed of the internal combustion engine can be set. As a result, there is provided a transmission control device capable of shifting while maintaining the rotation speed of the internal combustion engine in a high rotation range.

  By the way, a vehicle that automatically performs control for increasing the output of the internal combustion engine so as to increase the engine speed during the downshift (hereinafter also referred to as “blipping control”) has been put into practical use. In a vehicle in which clutch operation and shift operation are automated, this blipping control synchronizes the engine speed with the input shaft speed of the downshifted gear during downshift (during clutch release). By increasing this, it is possible to reduce the shock when the downshift is completed (when the clutch is engaged) and shorten the downshift time. Further, in a vehicle having the above-described torque converter, it is possible to synchronize the input shaft rotational speed and the output shaft rotational speed of the transmission with the speed ratio after the downshift during the downshift by performing blipping control. It is.

  In JP 2010-7491 A (Patent Document 2), regarding the blipping control described above, when the output of the internal combustion engine is increased during the downshift (when the blipping control is executed), the vehicle during the downshift is changed. If the deceleration (second vehicle deceleration) is continuously calculated and the second vehicle deceleration is smaller than the vehicle deceleration (first vehicle deceleration) at the time of the downshift request, the internal combustion engine The increase in output is reduced.

  As a result, even when the vehicle deceleration decreases during the downshift, it is possible to suppress the engine speed from exceeding the allowable speed during the downshift. In order to determine the amount of increase in the output increase of the internal combustion engine during blipping control only by comparing the vehicle deceleration with the vehicle deceleration at the time of downshift request, the change in vehicle deceleration due to the road gradient and the vehicle alternator It is easy to reflect disturbances such as changes in the internal combustion engine speed due to turning on and off, blipping control is frequently prohibited, and the internal combustion engine speed decreases during downshifts, causing shift shocks and down There is a problem that the acceleration after the shift is delayed from the driver's intention.

JP 2006-258125 A JP 2010-7491 A

  In order to cope with such a problem, the present invention enables a downshift that maintains the rotational speed of the internal combustion engine in a high rotation range in a vehicle that is controlled to increase the output of the internal combustion engine during the downshift. Accurately grasp the situation in which control to increase the output of the internal combustion engine should be prohibited during the shift, determine with a judgment element that can be detected directly, and prohibit control to increase the output of the internal combustion engine only in a necessary situation An object of the present invention is to provide a method for controlling an internal combustion engine of a vehicle.

  The control method of the present invention provided to solve the above-described problem is an internal combustion engine of a vehicle including an internal combustion engine and a transmission having an input shaft connected to the internal combustion engine and an output shaft connected to drive wheels. Control the engine. In this control method, in a vehicle that is controlled to increase the output of the internal combustion engine during downshifting, road downgradient detecting means for detecting the road downgradient at the time of the downshift operation instruction, and the rotational speed of the internal combustion engine are detected. And a rotation speed change rate calculating means for calculating a rotation speed change rate of the internal combustion engine. The control method includes a road downward gradient detected by the road downward gradient detection means at a time point when a downshift operation is instructed, and a rotational speed change rate of the internal combustion engine calculated by the rotational speed change rate calculation means. A means for setting a two-dimensional map, a threshold value for the rotational speed of the internal combustion engine determined based on the two-dimensional map, and the rotational speed of the internal combustion engine during the downshift are compared, and the rotational speed of the internal combustion engine is determined. The execution of the output increase control of the internal combustion engine is prohibited or interrupted only when it is larger than the threshold value.

  With the above configuration, the road descending gradient at the time when the downshift operation is instructed, the rotational speed of the internal combustion engine, and the rate of change of the rotational speed of the internal combustion engine are added to the determination elements, and the internal combustion engine is being reduced during the downshift. Control that increases the engine output accurately estimates the situation where the internal combustion engine speed is likely to exceed the allowable engine speed, and only in that case controls to increase the internal combustion engine output during downshift Can be prohibited.

  According to the present invention, when the downshift operation is instructed, the road downward gradient detected by the road downward gradient detecting means, the rotational speed change rate of the internal combustion engine calculated by the rotational speed change rate calculating means, A two-dimensional map is set, and the threshold value of the engine speed determined based on the two-dimensional map is compared with the engine speed during the downshift. The execution of the output increase control of the internal combustion engine is prohibited or interrupted only when the value is larger than. As a result, if the blipping control is performed, it is estimated that there is a high possibility that the rotational speed of the internal combustion engine exceeds the allowable rotational speed of the internal combustion engine (engine), and the blipping control is reliably prohibited only in a necessary situation. it can.

It is a block diagram which shows the structure of the vehicle by which the control method which concerns on one Embodiment of this invention is employ | adopted. 1 is a schematic diagram showing an example of a shift pattern of a vehicle that employs an internal combustion engine control method of the present invention. It is a flowchart of the control method based on one Embodiment of this invention. 4 is a timing chart of a downshift command signal, a maximum allowable engine speed, a reached speed at the next shift stage, an engine speed, and an opening degree of an electronic throttle valve when downshift is started in the present invention.

  With reference to FIG. 1 which is a block diagram showing a structure of a vehicle on which a control device according to an embodiment of the present invention is mounted, a vehicle block including ECU 100 that is a control device according to an embodiment of the present invention will be described. To do. The vehicle includes an engine 220, an automatic transmission 110, and a forward clutch 125 provided in the engine 220 and the automatic transmission 110.

  The input shaft of the automatic transmission 110 is connected to the crankshaft of the engine 220 via the forward clutch 125, and the output shaft of the automatic transmission 110 is connected to drive wheels (not shown) via a differential gear or the like. The vehicle travels as the rotation of the engine 220 is shifted by the automatic transmission 110 and transmitted to the drive wheels.

  The automatic transmission 110 is an automatic transmission such as a planetary gear type automatic transmission or a belt type continuously variable transmission connected to the engine 220 via a torque converter (not shown). There are a manual mode for executing upshift and downshift and an automatic mode for executing upshift and downshift according to a predetermined shift map. Note that the automatic mode may not be provided. The present invention fixes the gear ratio in the manual shift mode of the planetary gear type automatic transmission and in the belt type continuously variable transmission or the like (for example, the belt winding radii as the first speed to the sixth speed, respectively). This can be used for shift control in the manual shift mode of traveling. Furthermore, the transmission to which the present invention is applied is not limited to such an automatic transmission. For example, it may be called a semi-automatic transmission in which a clutch is engaged / released by a clutch actuator.

  In FIG. 1, the forward clutch 125 of the planetary gear type automatic transmission is controlled (engaged / released) by the clutch actuator 120. When forward clutch 125 is engaged (connected), power of engine 220 is transmitted to automatic transmission 110, and when forward clutch 125 is released (disconnected), power transmission from engine 220 to automatic transmission 110 is transmitted. Blocked. At the time of shifting while traveling, the forward clutch 125 and other clutches and brakes (not shown) are engaged and / or released to perform shifting.

  Further, the forward clutch 125 of the belt-type continuously variable transmission is controlled (engaged / released) by the clutch actuator 120. When the forward clutch 125 is engaged (connected), the power of the engine 220 is transmitted to the belt-type continuously variable transmission (automatic transmission) 110, and when the clutch 125 is released (disengaged), the belt is transferred from the engine 220 to the belt. Power transmission to the continuously variable transmission (automatic transmission) 110 of the type is interrupted. However, in a belt type continuously variable transmission, the forward clutch 125 is generally not released (disengaged) during traveling and shifting, and the winding radius of an unillustrated belt around an input pulley and an output pulley is not illustrated. The gears are changed by mutually changing.

  As an example, the clutch actuator 120 includes, as main components, a hydraulic pressure generation pump, an oil path switching valve, and a solenoid valve (not shown), and is incorporated in the automatic transmission. In the clutch actuator 120, the solenoid valve is controlled in accordance with a control signal from the ECU 100, whereby the oil path switching valve moves, and the forward clutch 125 and the clutch and brake (not shown) are released and engaged.

  The output of the engine 220 is controlled by a fuel injection amount or an intake air amount adjusted by an opening (throttle opening) β of an electronic throttle valve (not shown). The throttle opening β of the electronic throttle valve is controlled by the electronic throttle control system 210.

  A gear position sensor 130, an input shaft speed sensor 140, a shift lever position sensor 150, a vehicle speed sensor 160, a G sensor 170, an engine speed sensor 230, and a throttle opening sensor 250 are connected to the ECU 100 by a harness or the like.

  FIG. 2 schematically shows a shift pattern in a vehicle controlled by ECU 100 according to the embodiment of the present invention. The shift pattern shown in FIG. 2 is a right handle shift pattern, and the left handle pattern is a symmetrical pattern. This shift pattern allows the transmission to be parked (P position), reverse drive position (R position), neutral position (N position), automatic shift position (D position), manual shift position (M position), and M position. The driver can select upshift (+) or downshift (−) at.

  The position of the shift lever in the shift pattern shown in FIG. 2 is detected by shift lever position sensor 150 shown in FIG. Even when the driver sets the transmission position to the manual shift position (M position) and moves the shift lever to the downshift (−) side to request a downshift, the ECU 100 The downshift is not permitted until the engine speed NE falls below the downshift permission speed. This is because the engine speed NE after the downshift is kept lower than the maximum allowable engine speed NElim.

  However, when the vehicle is decelerating, the engine rotational speed NE continues to decrease as the rotational speed of drive wheels (not shown) decreases even during downshift. Therefore, the engine speed NE after the downshift is predicted based on the vehicle speed at the time of the downshift request, and the downshift is permitted only when the predicted engine speed is lower than the maximum allowable engine speed NElim. Since the engine speed NE decreases with time, the engine speed NE when the actual downshift is completed may be much lower than the maximum allowable engine speed NElim. In this case, the engine speed NE once decreases too much, causing a decrease in engine torque or the like, and the engine torque is insufficient and acceleration is accelerated even though the vehicle is desired to be accelerated immediately after the downshift is completed. , May be different from the driver's intention.

  Therefore, the ECU 100 reduces the engine speed NE during downshifting (in the case of a planetary gear type automatic transmission or semi-automatic transmission, in particular, from when the forward clutch 125 is released until it is engaged). The blipping control is executed to increase the speed so as to synchronize with the input shaft rotational speed NIN of the automatic transmission 110 when the shift is completed (when the forward clutch 125 is engaged).

  Specifically, ECU 100 determines engine speed NE during downshift based on the state of the vehicle (for example, engine speed NE, input shaft speed NIN, output shaft speed NOUT, gear ratio after downshift, etc.). The amount of increase in throttle (hereinafter also referred to as “the amount of blipping”) is calculated, the amount of increase in throttle opening β corresponding to the calculated amount of blipping is calculated, and the amount of increase in throttle opening β is calculated. The control signal (hereinafter also referred to as “blipping control signal”) is output to the electronic throttle control system 210. As a result, the engine speed NE is automatically synchronized with the input shaft speed NIN after the downshift, and the shock when the downshift is completed (when the forward clutch 125 is engaged) is reduced.

  The output period of the blipping control signal is set in consideration of a response delay until the engine speed NE is actually increased after the output of the blipping control signal. Therefore, for example, in the case of a planetary gear type automatic transmission or a semi-automatic transmission, the output start timing of the blipping control signal may be before the forward clutch 125 is released. In a belt-type continuously variable transmission, the forward clutch may not be released during blipping control. The blipping control is terminated when a predetermined time has elapsed since the start of the control. The blipping control time may be set to a value corresponding to the amount of blipping.

  Also, blipping control is frequently interrupted to reflect disturbances such as changes in vehicle deceleration due to road gradients and changes in engine speed due to turning on / off of a vehicle alternator (power generation device driven by the engine) (not shown). In some cases, the rotational speed of the internal combustion engine decreases during the downshift, causing a decrease in engine torque or the like, which is contrary to the driver's intention.

  As an example, FIG. 4 is a timing chart of a downshift command signal, the maximum allowable engine speed, the reached rotational speed at the next shift stage, the engine speed, and the opening of the electronic throttle valve when downshifting is started. As shown in FIG. 4, when the blipping control is executed at time t1 based on the downshift request, the downhill of the road increases during the subsequent downshift (t5 in FIG. 4), and the engine speed NE (FIG. 4). When the vehicle is decelerated more rapidly than when a downshift is requested (solid line B in FIG. 4), the engine speed NE may become the maximum allowable engine speed during downshift depending on the amount of blipping. There is a concern that NElim (dotted chain line C in FIG. 4) is exceeded (broken line B ′ in FIG. 4).

  Further, when the alternator changes from the on state (power generation is performed) to the off state (power generation is stopped) during the downshift, the engine load decreases, and as a result, the engine speed increases during the downshift. As a result, there is a concern that the engine speed NE may exceed the maximum allowable engine speed NElim during the downshift depending on the amount of blipping, as in the case where the road slope becomes large during the downshift described above. is there.

  In the conventional control method, it is possible to predict a disturbance such as an increase in the engine speed as described above, and prohibit the blipping control so that the engine speed NE does not exceed the maximum allowable engine speed NElim during the downshift. It was difficult.

  Therefore, in the present invention, a two-dimensional map is set from the road descending slope and the engine speed change rate, the engine speed threshold determined based on the map, and the engine speed NE during the downshift. And prohibiting the blipping control more reliably, determining the conditions under which the blipping control is possible, and actively executing the blipping control.

  With reference to FIG. 3, a control structure of a program executed when ECU 100, which is a control device according to the embodiment of the present invention, performs a downshift will be described.

  In step (hereinafter step is abbreviated as S) 100, ECU 100 determines whether or not a downshift request has been detected. This determination is made based on a signal input from shift lever position sensor 150 to ECU 100. If a downshift request is detected (YES in S100), the process proceeds to S110. If not (NO in S100), the process returns to S100 and waits until a downshift request is detected.

  In S110, ECU 100 is in a condition for executing blipping control, for example, that operation of engine speed sensor 230, throttle opening sensor 250, etc. is normal, upshift control is not being performed, etc. It is determined whether or not. If the condition is satisfied (YES in S110), the process proceeds to S120. If the conditions are not met (NO in S110), the process proceeds to S180, and the blipping control is prohibited or interrupted.

  In S120, ECU 100 detects a road descending slope. In addition, as a means for detecting a road descending slope, there is a method of calculating and using a deceleration ΔV (a vehicle speed at the time of downshift request and a value obtained by time differentiation) when requesting a downshift. It is preferable to detect using the G sensor 170 shown in FIG. 1 because it is possible to directly detect the road descending slope and to prohibit or interrupt the blipping control with high accuracy.

  In S130, ECU 100 detects engine speed NE. In step S140, the ECU 100 calculates the engine speed change rate ΔNE.

  In S150, ECU 100 sets a two-dimensional map from the road descending slope detected or calculated above and engine speed change rate ΔNE, and determines a threshold value for engine speed based on the map.

  In S160, ECU 100 determines whether or not engine speed NE detected above and a threshold value of engine speed determined based on the map are equal to or greater. If the engine speed is greater than the threshold value (NO in S160), the process proceeds to S180, and blipping control is prohibited or interrupted. If not (YES in S160), the process proceeds to S170.

In S170, ECU 100 permits the downshift request and executes the downshift.

  The operation of ECU 100, which is the control device according to the embodiment of the present invention based on the structure and flowchart as described above, will be described with reference to the timing chart shown in FIG.

  In FIG. 4, at time t1, the downshift command signal DS from the N-speed gear stage to the Nn-speed gear stage is output from the ECU 100, and the downshift command signal DS and the maximum allowable engine when the downshift is started. FIG. 6 schematically shows changes over time in the rotational speed NElim, the reached rotational speed NE1 at the next shift stage, the engine rotational speed NE, and the opening degree β of the electronic throttle valve.

  Conventionally, when performing blipping control during a downshift, only the deceleration ΔV is continuously calculated even during the downshift, and the deceleration ΔV during the downshift is reduced when the downshift is requested. Judging by only one condition whether or not the speed is smaller than VS, the blipping amount is reduced only when the deceleration △ V during downshift is smaller than the deceleration △ VS at the time of downshift request. I was letting. Therefore, as indicated by a broken line B ′ in FIG. 4, depending on the blipping amount, the engine speed NE may exceed the maximum allowable engine speed NElim (one-dot chain line C in FIG. 4) during the downshift. Even if it is not necessary to prohibit the blipping control, the blipping control may be prohibited or interrupted.

  Therefore, in the present invention, the road descending slope RS is detected by the G sensor 170 shown in FIG. 1 (S120 in FIG. 3), and the engine speed NE is detected by the engine speed sensor 230 shown in FIG. S130), the engine speed change rate NEC is calculated from the engine speed NE by the ECU 100 shown in FIG. 1 (S150 in FIG. 3).

  A two-dimensional map is set from the road downward gradient RS detected or calculated above and the engine speed change rate NEC, the engine speed threshold determined based on the map, and the engine speed during the downshift The number NE is compared to determine whether to prohibit the blipping control.

  As a result of the determination by the above-described means, when the blipping control is executed, a state in which the throttle opening β is increased until the time t3 with the target rotational speed NE1 at the next shift speed indicated by the alternate long and short dash line D in FIG. By continuing to decrease the throttle opening β at time t3, the engine speed NE reaches the next gear stage engine speed NE1 at time t4, and the allowable engine speed NElim indicated by a one-dot chain line C in FIG. Downshift is completed without exceeding. In other words, it is possible to appropriately suppress the engine speed NE from exceeding the maximum allowable engine speed NElim during the downshift and after the downshift.

  On the other hand, when the engine speed change rate NEC changes at time t5 due to disturbance and the engine speed NE changes as shown by the solid line B in FIG. As shown in FIG. 4, the blipping control is interrupted at time t2 to reduce the throttle opening β. With the above control, the engine speed NE can be prevented from exceeding the allowable engine speed NElim indicated by a one-dot chain line C in FIG. 4 at time t6.

As described above, when performing the blipping control during the downshift, the control device according to the present embodiment sets a two-dimensional map from the road descending slope and the engine speed change rate, and adds the two-dimensional map to the map. The threshold value of the engine speed determined based on the engine speed NE during downshift is compared, and if the engine speed NE is greater than the threshold value, the blipping control is more accurately prohibited or interrupted. The condition for enabling the blipping control is determined, and the blipping control is actively executed. This allows the engine speed to be allowed during downshift, even when the road gradient increases during downshift and the alternator changes from ON to OFF and the engine speed increases. Judging the conditions under which blipping control is possible while suppressing the engine speed from exceeding the engine speed, and actively executing the blipping control, the engine speed is maintained in the high engine speed range to achieve shifting. Thus, it is possible to solve the problem that a shift shock occurs or the acceleration after the downshift is delayed from the driver's intention.

  The acceleration of the vehicle may be added to a determination element that prohibits or interrupts the blipping control.

  Further, depending on the magnitude of the difference in engine speed between the engine speed at the gear position and the engine speed at the next gear speed, a preset threshold value for road descent gradient, threshold value for engine speed, and threshold value for engine speed change rate are set. , One or a plurality of them may be changed.

  By adding one or more of the above-mentioned means, the control for increasing the output of the internal combustion engine during the downshift can be prohibited more securely, while the blipping control is not necessarily prohibited. Thus, it is possible to execute blipping control.

  The embodiment of the internal combustion engine control method of the present invention has been described above, but the present invention is not limited to this embodiment, and other embodiments do not depart from the spirit and teaching described in the claims and the description. It will be understood by those skilled in the art that variations and improvements can be obtained.

100 ECU
110 Automatic transmission 120 Clutch actuator 125 Clutch 130 Gear position sensor 140 Input shaft rotation sensor 150 Shift lever position sensor 160 Vehicle speed sensor 170 G sensor 210 Electronic throttle control system 220 Engine 230 Engine speed sensor 240 Accelerator position sensor 250 Throttle opening sensor 260 Engine torque sensor β Electronic throttle valve opening (throttle opening)
NE Engine speed Nelim Maximum allowable engine speed NIN Input shaft speed NOUT Output shaft speed △ V Deceleration △ NE Engine speed change rate DS Downshift command signal NE Speed reached at the first gear stage RS Road downhill speed NEC Engine speed change rate

Claims (1)

An internal combustion engine control method for a vehicle, comprising: an internal combustion engine; and a transmission having an input shaft connected to the internal combustion engine and an output shaft connected to drive wheels,
In a vehicle that is controlled to increase the output of the internal combustion engine during downshifting, road downhill detecting means for detecting the road downhill at the time of the downshift operation instruction;
A rotational speed detecting means for detecting the rotational speed of the internal combustion engine;
A speed change rate calculating means for calculating a speed change rate of the internal combustion engine;
With
The internal combustion engine control method includes:
When a downshift operation is instructed, a two-dimensional map is set from the road downward gradient detected by the road downward gradient detecting means and the internal combustion engine rotational speed change rate calculated by the rotational speed change rate calculating means. And
The internal combustion engine speed threshold determined based on the two-dimensional map is compared with the internal combustion engine speed during the downshift, and the internal combustion engine is used only when the internal combustion engine speed is greater than the threshold. Prohibit or interrupt the execution of engine output increase control,
A method for controlling an internal combustion engine of a vehicle.