JP2008231992A - Drive control device of vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shift with good responsiveness while suppressing the excessive rise of an exhaust gas temperature during the shifting. <P>SOLUTION: When a continuously variable transmission is manually shifted from a second stage to a fourth stage, it is determined whether the shifting is completed or not within a continuable time t set in consideration of the effect of an ignition timing retard angle control on the exhaust gas temperature while performing the ignition timing retard angle control (torque down control). When the shifting is determined to be not completed, an ignition timing retard angle amount is gradually returned to an advance angle side while limiting the ignition timing retard angle amount by an ignition timing limiter Tlim so set as to limit a vehicle acceleration to an allowable acceleration G0. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a control technique for performing torque-down control by retarding an ignition timing of an engine when shifting a transmission in a vehicle drive system.

  Japanese Patent Laid-Open No. 2004-228561 performs control (torque down control) for reducing engine torque to alleviate a shift shock at the time of shifting for an automatic transmission. When ignition timing retardation control is used, torque is reduced with good response. However, if the ignition timing is retarded, the exhaust temperature rises and affects the exhaust purification catalyst. Therefore, the ignition timing retard control is performed only for a predetermined time after the start of the shift operation.

Patent Document 2 discloses a V-belt type or toroidal type continuously variable transmission that can be shifted to a fixed gear position by a manual gear shifting operation, and performs torque down control during upshifting. In this case as well, the ignition timing retarding control can increase the torque down speed and perform a shift with good response. However, particularly when performing an upshift of two or more stages, the time required for the end of the shift is lengthened and the shift ends. It is not preferable to continue the control with the retard amount greater than a predetermined amount until the exhaust purification catalyst is affected.
Japanese Patent Laid-Open No. 10-110639 JP 2006-22913 A

  However, in Patent Document 1, since the ignition timing is retarded for a predetermined time and then returned to the advance side at once, a large torque shock is generated.

  It is not preferable that the ignition timing retarding control is continued for a long time in order to avoid the influence of the exhaust purification catalyst at the time of upshifting by the manual command of the continuously variable transmission shown in Patent Document 2. When the retard control is terminated, a large torque shock is similarly generated.

  The present invention has been made paying attention to such a conventional problem, and in the torque-down control by retarding the ignition timing at the time of shifting, the shifting is terminated as quickly as possible while suppressing an excessive increase in the exhaust gas temperature. The purpose is to be able to.

In order to solve this problem, the present invention provides:
In a vehicle drive control device that performs torque down control by retarding the ignition timing of the engine during shift control of a transmission connected to the engine,
It is determined whether or not the shift control is finished within the continuation limit time of the ignition timing retarding control set according to the exhaust gas temperature rise accompanying the ignition timing retarding control. It is characterized by limiting the amount of retardation in the timing retardation control.

  When the ignition timing retarding control is performed, the exhaust gas temperature rises. Therefore, the continuation limit time of the ignition timing retarding control is set so as not to affect the exhaust purification catalyst.

  Then, when it is determined that the shift is not completed within the continuation limit time during the shift, the retard amount in the ignition timing retard control is limited. As a result, the shift can be finished as quickly as possible by performing the torque-down control while suppressing an excessive increase in the exhaust temperature due to the ignition timing retardation.

  FIG. 1 is a schematic diagram illustrating a vehicle drive system in the embodiment.

  The vehicle drive system shown in FIG. 1 includes an engine 1 and a continuously variable transmission 3 connected to the engine 1 via a lock-up torque converter 2.

  The crankshaft 101 of the engine 1 is coupled to the input side 21 of the torque converter 2, and the input shaft 301 of the continuously variable transmission 3 is coupled to the output side 22 of the torque converter 2.

  The output shaft 302 of the continuously variable transmission 3 is connected to the wheel drive shaft 7 and the drive wheel 8 via the propeller shaft 4, the final gear 5, and the differential gear 6.

  The continuously variable transmission 3 is a continuously variable transmission that uses a pair of variable groove width pulleys and a belt made of metal or the like wound around them, and includes a primary pulley 303 provided on the input shaft 301 side, an output shaft A secondary pulley 304 provided on the 302 side, hydraulic cylinders 305 and 306 for changing groove widths (effective diameters) of the pulleys 303 and 304, and a belt 307 wound around the pulleys 303 and 304, respectively. Consists of including.

  In the continuously variable transmission 3 configured as described above, the pulley ratio changes by controlling the hydraulic pressure of the hydraulic cylinders 305 and 306, and the gear ratio changes steplessly according to the change in the pulley ratio.

  In addition, the continuously variable transmission 3 is configured to perform automatic shift control in the automatic shift (D) range, and to perform shift control to a fixed shift stage by a manual shift operation in the manual shift (M) range. Has been.

  The range sensor 308 attached to the continuously variable transmission 3 includes a shift lever that is parked (P) range, reverse travel (R) range, neutral (N) range, forward automatic shift (D) range, and manual shift (M) range. The shift position is detected.

  The engine 1 is equipped with an air flow meter 102 for detecting an intake air flow rate in an intake passage 100, a butterfly throttle valve 103, and the like. The throttle valve 103 is driven to open and close by a throttle actuator (for example, a motor) 104 to reduce the intake air amount. An electric throttle 105 for adjustment is provided.

  In addition, a fuel injection valve 106 for injecting fuel into the intake port or cylinder of each cylinder, an ignition plug 107 attached to the combustion chamber, and the like are provided.

  Further, an air-fuel ratio sensor 109 that detects an exhaust air-fuel ratio, an exhaust purification catalyst 110, and the like are interposed in the exhaust passage 108 of the engine 1.

  The engine control unit (hereinafter referred to as “ECU”) 10 receives detection signals from the air flow meter 102, the air-fuel ratio sensor 109, a rotation speed sensor 111 that detects the engine rotation speed, a vehicle speed sensor 112 that detects the vehicle speed, and the like. Based on these detection signals, engine control such as intake air amount control, fuel injection control, and ignition timing control in the engine 1 is performed.

  On the other hand, the transmission control unit (hereinafter referred to as “TCU”) 20 inputs detection signals from the range sensor 308, the vehicle speed sensor 112, the throttle sensor 113 for detecting the opening degree of the throttle valve 103, etc. Shift control is performed by controlling the lockup / lockup release switching operation in the rotary torque converter 2 and the operations of the hydraulic cylinders 305 and 306 in the continuously variable transmission 3. Note that the lockup type torque converter 2 is locked up during manual shifting of the continuously variable transmission 3 described later.

  The EUC 10 and the TCU 20 are connected so as to communicate with each other.

  Hereinafter, specific control of the continuously variable transmission 3 will be described.

  When the continuously variable transmission 3 is in the automatic shift (D) range, the target input speed DSRREV is calculated from the throttle opening TVO and the vehicle speed VSP based on the shift map, and this target input speed DSRREV is calculated as the transmission output speed. By dividing by No (obtained from the vehicle speed VSP), the target gear ratio tR is calculated, and the gear ratio is controlled by performing hydraulic control based on the target gear ratio tR.

  On the other hand, when the manual transmission (M) range is selected, a gear position (first speed: GP1) having a preset fixed gear ratio shown in the shift map in the manual transmission (M) range illustrated in FIG. , 2nd speed: GP2, 3rd speed: GP3, 4th speed: GP4, 5th speed: GP5, 6th speed: GP6).

  Specifically, immediately after switching from the automatic shift (D) range to the manual shift (M) range, the gear position that becomes the target input rotational speed DSRREV that is closest to the current input rotational speed under the current vehicle speed VSP is set. After that, every time there is a manual shift command by the driver, if it is an upshift command, the next high-speed gear is set as a new target shift step, an upshift to this is commanded, and the downshift command If there is, the next low speed side shift stage is set as a new target shift stage and a downshift to this is commanded.

  Then, based on the shift line characteristic in FIG. 2 corresponding to the target shift speed determined as described above, the target input rotation speed DSRREV is obtained from the vehicle speed VSP, and divided by the transmission output rotation speed No to obtain the target shift speed. A corresponding target speed ratio tR0 to be finally converged is obtained.

  While continuously calculating and updating the target speed ratio tR0 so as to approach the target speed ratio tR0, the transmission of the continuously variable transmission 3 is controlled, and the torque of the engine 1 is controlled so as to approach the target input speed DSRREV.

  This basic control is the same as in the case of automatic transmission control. However, in the case of automatic transmission control, the target transmission ratio changes gently according to the driving state, so that it can be converged to the target transmission ratio with high response. On the other hand, in the case of manual shift control, there is a demand to shorten the shift completion time as much as possible by increasing the shift speed while increasing the shift speed because the target shift ratio changes stepwise.

  For this reason, when performing control to reduce the engine torque during upshifting, ignition timing retarding control is executed that can reduce the torque with good response.

  However, as described above, if the ignition timing retardation control is prolonged, the exhaust gas temperature rise of the engine 1 will affect the exhaust purification catalyst. Therefore, in the present invention, when the completion of the shift is prolonged, by limiting the retard amount of the ignition timing retard control, the retard amount is gradually decreased to avoid the influence of the exhaust gas temperature rise.

  FIG. 3 shows a control flow at the time of shifting accompanied with torque reduction control of the engine according to the present invention.

  In step S1, various variables used in this control are updated.

  Specifically, the target shift destination ratio tR0, the target shift ratio tR, the difference ΔR from the previous value of the target shift ratio tR, the ignition timing retardable duration t, and the shift control torque down command value T are updated.

  The target shift destination ratio tR0 is a target speed ratio calculated as described above based on the target shift speed that is most recently determined by a manual shift operation.

  The target speed ratio tR is a sequential target speed ratio calculated when the current target speed ratio is changed from the current target speed ratio to the target speed target ratio R0 with a characteristic that converges with a predetermined time constant. This time constant is a value that determines the shift speed. Compared to the time constant at the time of automatic shift, the time constant is set to a small value at the time of manual shift so that the shift speed is maximized.

  The shift control torque down command value T is a command value for torque reduction in torque down control during upshifting, and a retard amount command value in ignition timing retard control is set based on this command value.

  The ignition timing retarding continuation possible time t is an initial value of a limit time set in consideration of the effect on the exhaust purification catalyst due to the exhaust gas temperature rise when the control is continued with the ignition timing retarding amount in the torque down control. And calculated by subtracting the elapsed time from the start of control.

  The initial value of the ignition timing retardable continuation time t may simply be constant, but may be variably set according to the exhaust temperature at the start of the present control using the detected value or estimated value of the exhaust temperature. For example, it can be set short when the exhaust temperature at the start of control is high, and long when the exhaust temperature is low.

  In step S2, it is determined whether or not the shift is completed within the ignition timing retardation continuation possible time t updated in step S1.

  Specifically, since the estimated time from the current time until the end of the shift is calculated as (R0−tR) / ΔR, it is determined whether (R0−tR) / ΔR is greater than t.

  If it is determined in step S2 that (R0−tR) / ΔR is equal to or less than t and the shift can be completed within the ignition timing retardation continuation possible time t, at present, ignition timing retardation control (torque down control) is performed. Since it is not necessary to perform the restriction, the process proceeds to step S3, the final torque-down command value Tnew is maintained at the torque-down command value T updated in step S1, and the process returns to step S1.

  If it is determined in step S3 that (R0−tR) / ΔR is greater than t and the shift is not completed within the ignition timing retardation continuation possible time t, the process proceeds to step S4 and the subsequent steps, and the ignition timing retardation Control for limiting the amount of retardation in the control is executed.

  In step S4, the torque down limiter Tlim, which is the amount of retard amount, is set so that the vehicle acceleration that occurs when the retard amount is limited and returned to the advance side is limited to the allowable acceleration G0 that the occupant can tolerate. Set as follows.

  First, based on the allowable acceleration G0, the allowable torque increase rate ΔTlim is calculated by the following equation. Here, the allowable acceleration G0 is an acceleration with the vehicle deceleration direction being positive, and therefore the value of the allowable acceleration G0 is a negative value.

ΔTlim = G0 × 9.81 × m × r / (if × i)
m: vehicle weight r: tire radius if: gear ratio of final gear i: gear ratio of continuously variable transmission (pulley effective diameter ratio)
Next, the torque down limiter Tlim is calculated by the following equation.

Tlim = ΔTlim × (t−td)
Here, td is a difference in response delay time between the engine 1 and the continuously variable transmission 3, and since the engine 1 has a faster response than the continuously variable transmission 3, the torque down limiter Tlim is subjected to a filtering process described later. The delay control is completed in synchronization with the end of the shift of the continuously variable transmission 3 by providing a delay. Here, since t is a value calculated by subtracting with the elapsed time from the limit time, which is the initial value as described above, the value of the torque down limiter Tlim gradually increases (absolute value) with the elapsed time. Decrease).

  In step S5, the torque down command value T is compared with the torque down limiter Tlim.

  When T ≧ Tlim (the torque down value is set as a negative torque value, if it is determined that | T | ≦ | Tlim | as an absolute value), the torque down command value T is still the torque down limiter Tlim. In step S3, the final torque-down command value Tnew is maintained at the torque-down command value T updated in step S1, and the process returns to step S1.

  If it is determined in step S5 that T <Tlim, the vehicle acceleration is limited to the allowable acceleration G0. Therefore, it is determined that the timing required to start the ignition timing retard control is reached, and the process proceeds to step S6 and subsequent steps. .

  In step S6, control for reducing the shift speed is started. This is performed in order to reduce the speed of the engine 1 in synchronism with the decrease in the deceleration of the engine 1 as the torque reduction amount is limited by limiting the ignition timing retardation amount that is simultaneously performed.

  In step S7, a limit process for limiting the torque down command value T by the torque down limiter Tlim is performed. This is a process of selecting the larger of T and Tlim (smaller absolute value), but the torque-down command value Tnew0 subjected to the limit process becomes Tlim according to the determination result in step S5.

  In step S8, the torque-down command value Tnew0 is subjected to filter processing (first-order lag, weighted average processing, etc.) to obtain a torque-down command value Tnew that is finally output. By performing such filter processing, the end of the torque down control of the engine 1 that is faster in response than the continuously variable transmission 3 is delayed, and the end of the shift of the continuously variable transmission 3 and the end of the torque down control are synchronized. In addition, the occurrence of a torque step (torque shock) at the end of shifting is suppressed.

  In step S9, it is determined whether the ignition timing retardation continuation possible time t is 0 or the shift is completed, and when either is satisfied, the shift control is ended.

  FIG. 4 shows changes in various state quantities when a two-stage upshift operation is performed from the second speed GP2 to the fourth speed GP4 by manual shifting.

  First, from the time when the second speed GP2 is upshifted to the third speed GP3, an increase in the shift speed is permitted (a permission signal rises) from the determination that a manual shift operation has been performed. As a result, the target speed ratio is calculated at a large speed using a small time constant as described above, and the actual speed ratio changes with a delay from the target speed ratio.

  At the same time, the expected time [= (R0−tR) / ΔR] until the end of the shift increases stepwise, but at the time of upshifting to the third speed, it is smaller than the ignition timing delay continuation possible time t. Judgment to limit timing retard control is not made. If it is a one-stage upshift to the third speed, there is no need to limit ignition timing retard control.

  Torque down control is also started, and the torque down command value T is calculated as a negative value from the change rate of the target gear ratio, and the ignition timing retard amount increases in accordance with the torque down command value T.

  Next, when the upshift is performed from the 3rd speed to the 4th speed, the expected time [= (R0−tR) / ΔR] until the end of the shift further increases stepwise and exceeds the ignition timing retardation continuation possible time t. At this point, it is determined that the torque reduction control is limited, that is, the retard amount of the ignition timing retard control is limited.

  Then, when the torque-down command value T becomes smaller than the torque-down limiter Tlim calculated corresponding to the allowable acceleration G0, the limitation by the torque-down limiter Tlim is started, and the filtered torque-down command value Tnew is started. Accordingly, the ignition timing retard amount starts to decrease.

  At the same time, the shift speed increase permission signal is reset, the shift speed increase is prohibited, and the shift speed is reduced to the same shift speed as in the automatic shift, and the target speed ratio tR is calculated according to this shift speed.

  In this way, when the shift time is prolonged, such as during multiple shift-up operations, the retard amount of the ignition timing retard control is limited and gradually returned to the advance side, so that the exhaust due to the exhaust temperature rise can be reduced. While avoiding the influence on the purification catalyst, it is possible to avoid a shock due to a sudden torque increase.

  Further, by performing ignition timing retard control with good responsiveness while limiting the retard amount until the end of the shift, the shift time can be shortened as much as possible.

  Further, when it is determined that the shift is completed within the ignition timing delay continuation possible time t while comparing the estimated shift time with the ignition timing retardation continuation possible time t, the retard amount is not limited. Shifting time can be shortened as much as possible by delaying the start timing as much as possible even when limiting.

  Also, when limiting ignition timing retarding control (torque down control) on the engine 1 side, a change in vehicle acceleration is suppressed by cooperative control that simultaneously performs control to reduce the shifting speed on the continuously variable transmission 3 side. it can.

  Further, by performing the limit control of the ignition timing retarding control (torque down control) while setting the allowable acceleration G0, the shift time can be shortened to the maximum while suppressing the vehicle acceleration within the allowable range.

  In addition, by considering the difference in response delay between the engine 1 and the continuously variable transmission 3, the torque reduction limit value is filtered to synchronize the end of the shift and the end of the torque down control. The occurrence of a torque step (torque shock) can also be reliably suppressed.

  In this embodiment, the present invention is applied to manual shifting of a continuously variable transmission, and the effect of avoiding shift shock by applying the present invention is great. However, the present invention is a stepped automatic transmission (AT). The present invention can also be applied when shifting is performed in the automatic mode or manual mode. In this case, the shift time is a value experimentally obtained in advance for each shift pattern, and when the torque down control is performed by the ignition timing retard control at the time of shift (in addition to the shift up, the accelerator opening suddenly increases during rapid acceleration). In other words, the retard amount may be limited when the ignition timing retard continuation possible time t exceeds the shift time.

It is the schematic which shows the drive system of the vehicle in embodiment of this invention. It is a shift diagram for manual transmission (M) range of the continuously variable transmission used in the embodiment. It is a flowchart which shows the speed change control accompanied with the torque down control of the engine which concerns on embodiment same as the above. It is a time chart which shows the mode of the change of the various state quantities at the time of control same as the above.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Engine, 2 ... Lock-up type torque converter, 3 ... Continuously variable transmission, 10 ... Engine control unit (ECU), 20 ... Transmission control unit (TCU), 107 ... Spark plug, 110 ... Exhaust gas purification catalyst, 111 ... Rotational speed sensor, 112 ... Vehicle speed sensor, 113 ... Throttle sensor, 308 ... Range sensor

Claims (6)

In a vehicle drive control device that performs torque down control by retarding the ignition timing of the engine during shift control of a transmission connected to the engine,
It is determined whether or not the shift control is finished within the continuation limit time of the ignition timing retarding control set according to the exhaust gas temperature rise accompanying the ignition timing retarding control. A drive control device for a vehicle, which limits a retard amount in timing retard control.   2. The shift speed is decreased before the end of the continuation limit time when it is determined that the shift control is not completed within the continuation limit time of the ignition timing retardation control and the retardation amount is limited. The vehicle drive control apparatus described.   3. The vehicle drive control device according to claim 1, wherein the restriction start timing and the restriction amount of the retardation amount are set so that the torque-down control is completed before the end of the shift.   4. The vehicle drive control device according to claim 3, wherein the retard start amount restriction start time and the restriction amount are set such that the vehicle acceleration is maintained below an allowable value.   5. The vehicle drive control device according to claim 4, wherein the restriction start timing and the restriction amount of the retardation amount are set in consideration of a response delay between the engine and the transmission.   6. The transmission according to claim 1, wherein the transmission is a continuously variable transmission having a manual transmission operation function, and the torque reduction control of the engine is performed during a manual transmission operation. Vehicle drive control device.

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