WO2015129701A1

WO2015129701A1 - Drive source control device and drive source control method for vehicle

Info

Publication number: WO2015129701A1
Application number: PCT/JP2015/055268
Authority: WO
Inventors: 博昭片瀬
Original assignee: 日産自動車株式会社
Priority date: 2014-02-26
Filing date: 2015-02-24
Publication date: 2015-09-03

Abstract

　A drive source control device for a vehicle controls a vehicular drive source having a powertrain in which a drive source and an automatic transmission are coupled via a torque converter provided with a lock-up clutch, wherein the drive source control device is provided with: a torque down command means for issuing a torque down command to the drive source to ensure that the drive source torque does not exceed an upper limit torque command value required by the automatic transmission; an upper limit torque command value setting means for calculating the upper limit torque command value so that the drive source speed, which rises when the vehicle starts moving, recedes to a drive source target speed; and a torque down control means for receiving the torque down command and performing torque down control so that the drive source torque does not exceed the upper limit torque command value.

Description

Vehicle drive source control apparatus and drive source control method

The present invention relates to a vehicle drive source control device and a drive source control method.

When a torque converter is attached to the automatic transmission, when the driver depresses the accelerator pedal at the start of the vehicle, the acceleration from the start of the vehicle rises sharply at the beginning of the start, takes a peak, and then decreases sharply Tend to become an acceleration waveform. For this reason, the engine speed rapidly increases when the vehicle starts and overshoots across the target engine speed. Due to the overshoot characteristics of the acceleration waveform and the engine rotational speed, the driver (driver) feels that there is too much acceleration at the beginning of the start. In order to cope with this, there is an engine that corrects the throttle valve opening to be smaller than the basic throttle valve opening in the low accelerator opening region when the vehicle starts, targeting an engine having an electronically controlled throttle valve ( JP 2006-125213A). Here, the basic throttle valve opening is set according to the accelerator opening (the amount of depression of the accelerator pedal).

By the way, in the technique of the above-mentioned document, since the throttle valve opening is made smaller than the basic throttle valve opening, the overshoot of the engine rotation speed and the acceleration peak at the start of the vehicle are suppressed, so the entire acceleration waveform is similar. Will be reduced. For this reason, if the driver feels that there is a lack of acceleration and then depresses the accelerator pedal, the engine speed may be increased or the acceleration peak may not be suppressed as intended.

Therefore, an object of the present invention is to provide a device that can suppress an unnecessary engine speed increase when the vehicle starts and can improve the controllability of acceleration in a low accelerator opening range.

According to an aspect of the present invention, a vehicle drive source control device is premised on a vehicle having a power train in which a drive source and an automatic transmission are connected via a torque converter having a lock-up clutch. Further, a torque down command means, an upper limit torque command value setting means, and a torque down control means are provided. The torque down command means issues a torque down command for preventing the drive source torque from exceeding the upper limit torque command value required by the automatic transmission. The upper limit torque command value setting means calculates the upper limit torque command value so that the drive source rotational speed that rises when the vehicle starts is within the target engine rotational speed. The torque down control means receives the torque down command and performs torque down control so that the drive source torque does not exceed the upper limit torque command value.

According to the above aspect, it is possible to suppress an unnecessary blow-up in which the engine rotational speed at the time of starting the vehicle overshoots across the target rotational speed of the engine, and improves the controllability of acceleration in the low accelerator opening range. be able to.

FIG. 1 is a schematic configuration diagram of a vehicle having a power train according to a first embodiment of the present invention. FIG. 2 is a characteristic diagram showing the relationship between the accelerator opening and the peak value of acceleration. FIG. 3 is a timing chart showing changes in the throttle valve opening, engine torque, and engine speed when the vehicle starts. FIG. 4 is a control block diagram for calculating the upper limit torque command value. FIG. 5 is a flowchart for explaining the setting of the start flag. FIG. 6 is a flowchart for explaining the setting of the torque-down command flag. FIG. 7 is a flowchart for explaining calculation of the engine torque command value and the ignition timing command value. FIG. 8 is a characteristic diagram of basic engine torque. FIG. 9 is a flowchart for explaining calculation of an engine torque command value according to the second embodiment. FIG. 10 is a timing chart showing changes in the accelerator opening, throttle valve opening, engine torque, and vehicle acceleration when the vehicle starts.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

(First embodiment)
FIG. 1 is a schematic configuration diagram of a vehicle 1 having a power train 2 to which the first embodiment of the present invention is applied. The power train 2 includes an engine 3, a torque converter 31 including a lock-up clutch 34, a CVT (belt type automatic transmission) 41, a final drive gear 51, a differential gear 52, and a drive shaft 53.

In FIG. 1, the air introduced from the intake passage 4 is supplied to the combustion chamber 6 of the gasoline engine 3 as a drive source through the intake port 5 of each cylinder. The amount of air supplied to the combustion chamber 6 is adjusted by the opening of an electronically controlled throttle valve 11 provided in the intake passage 4 (hereinafter referred to as “throttle valve opening”). The throttle valve 11 has its throttle valve opening controlled by a throttle motor 12. The actual throttle valve opening is detected by the throttle sensor 13 and input to the engine controller 21 described later.

The engine 3 includes a fuel injection valve 7 in each intake port 5. The fuel injection valve 7 intermittently supplies fuel toward the air flowing through the intake port 5. The engine 3 includes a spark plug 8 facing the combustion chamber 6. The air flowing into the combustion chamber 6 is mixed with fuel and becomes an air-fuel mixture. The engine controller 21 generates a spark in the spark plug 8 by interrupting the primary current of the ignition coil at a predetermined time before the compression top dead center, thereby igniting the air-fuel mixture in the combustion chamber 6. The gas combusted by this ignition is discharged to an exhaust passage (not shown).

The engine controller 21 controls the engine 3 in addition to the ignition control described above. The engine controller 21 receives an accelerator opening signal (depression amount of the accelerator pedal 22) from an accelerator opening sensor 23, a crank angle signal from a crank angle sensor (engine speed sensor) 24, and an intake from an air flow meter 25. An air volume signal is input. From the signal of the crank angle sensor 24, the rotational speed of the engine 2 is calculated. The engine controller 21 calculates the target intake air amount and the target fuel injection amount based on these signals, and applies the throttle motor 12 and the fuel injection valve 7 of each cylinder so as to obtain the target intake air amount and the target fuel injection amount. Issue a command.

The torque converter 31 and the CVT 41 are connected to the output shaft of the engine 3. The torque converter 31 has a pump impeller 32 and a turbine runner 33. The CVT 41 includes a forward / reverse switching mechanism 42, a primary pulley 43, a secondary pulley 44, and a steel belt 45 that is wound around the

pulleys

43 and 44. The rotational driving force of the engine 2 is finally transmitted to the vehicle drive wheels 54 via the torque converter 31, CVT 41, final drive gear 51, differential gear 52, and drive shaft 53.

The vehicle 1 includes a CVT controller 61 for controlling the CVT 41. The CVT controller 61 receives the input rotation speed Nt from the input rotation speed sensor 61 and the output rotation speed No from the output rotation speed sensor 62. Since the input shaft of the CVT 41 is connected to the turbine runner 33, the input rotational speed is also the rotational speed of the turbine runner 33 (turbine rotational speed). The CVT controller 61 calculates the vehicle speed VSP based on the output rotation speed No, the final drive gear 51, and the effective tire radius of the drive wheel 53. The CVT controller 6 controls the transmission ratio of the CVT 41 in a stepless manner in accordance with the traveling conditions of the vehicle 1 determined from the vehicle speed VSP and the throttle valve opening TVO.

The CVT controller 61 and the engine controller 21 are connected by CAN (Controller / Area / Network). The engine speed Ne, the throttle valve opening TVO, the engine torque command value Te, and the basic engine torque Te0 are input from the engine controller 21 to the CVT controller 61 via the CAN communication.

The torque converter 31 includes a mechanical lock-up clutch 34 that fastens and opens the pump impeller 32 and the turbine runner 33. The CVT controller 61 predetermines a traveling region of the vehicle for fastening the lockup clutch 34 as a lockup region (vehicle speed and throttle opening are used as parameters). The CVT controller 61 brings the engine 3 and the CVT 41 into a direct connection state by engaging a lock-up clutch when the vehicle traveling condition is in the lock-up region. On the other hand, when the running condition of the vehicle is not in the lockup region, the CVT controller 61 releases the lockup clutch 34. When the engine 3 and the CVT 41 are in a directly connected state, loss due to differential rotation in the torque converter 31 is eliminated, and fuel consumption is improved accordingly.

Now, when the torque train 31 is included in the powertrain 2, when the driver depresses the accelerator pedal 22 when the vehicle 1 starts, the acceleration suddenly increases at the beginning of the vehicle, takes a peak, and then decreases rapidly. Tend to. For this reason, the engine speed rapidly increases when the vehicle starts and overshoots across the target engine speed. Due to these characteristics of acceleration and engine speed, the driver feels that there is too much acceleration at the beginning of the start.

More specifically, the relationship between the accelerator opening APO and the acceleration peak value Gp in a control state (hereinafter referred to as “normal control”) in which torque down control described later is not executed is shown by a broken line in FIG. The acceleration peak value Gp is proportional to the torque converter output torque Tt, and the torque converter output torque Tt is determined by the following equation.

Tt = t · τ · Ne 2 (1)
Where t: torque ratio [unknown number],
τ: Coefficient of torque capacity [10-6 · Nm / rpm2],
Ne: Engine rotation speed [rpm],
In normal control, as shown by a broken line in FIG. 2, the acceleration peak value Gp rises steeply in a low accelerator opening range near zero. As a result, in the low accelerator opening range, it becomes difficult for the driver to obtain the desired acceleration even if the driver adjusts the accelerator opening in order to obtain the desired acceleration. This is because the decomposition performance of the acceleration peak value with respect to the accelerator opening deteriorates in the low accelerator opening range. For example, the minimum unit (decomposition performance) that the driver can step on the accelerator pedal 22 is, for example, about 1 cm. In this case, even if it is known that how much mm the accelerator pedal 22 is depressed to obtain the desired acceleration, it is impossible for the driver to accurately decrement how many mm.

This will be further described with reference to FIG. FIG. 3 is a timing chart showing how the throttle valve opening TVO, the engine torque, the target engine speed tNe, and the actual engine speed Ne change when the vehicle starts. The torque down command flag shown at the bottom of FIG. 3 will be described later.

When the vehicle stops before the timing t1, the throttle valve opening TVO is set to the initial opening state of zero, and the target engine speed tNe is set to the target engine speed NSET during idling. On the other hand, the actual engine rotational speed Ne should normally coincide with the target rotational speed NSET during idling, but here it is assumed that the rotational speed is lower than the target rotational speed NSET during idling for some reason. Yes.

When the accelerator pedal 22 is depressed by a certain amount at timing t1 and the throttle valve opening TVO changes from 0 to a predetermined value TVO1, the throttle valve opening TVO maintains a constant value (TVO1) from timing t2. In response to the change in the throttle valve opening TVO, the target engine speed tNe of the engine also becomes higher than the target engine speed NSET during idling at timing t1, and the predetermined value tNe1 is held from timing t2. Further, in response to the change in the throttle valve opening TVO, the basic engine torque Te0 changes substantially in accordance with the change in the throttle valve opening TVO as shown by the solid line in the second stage from the top of FIG. In the case of normal control, the actual engine rotational speed Ne is slightly delayed by the basic engine torque Te0 from the timing t1 at which the throttle valve opening TVO increases as shown by the broken line in the third stage from the top of FIG. Rise. Then, at timing t3, it greatly overshoots across the target rotational speed tNe of the engine 3 and then decreases and converges to the target rotational speed tNe.

On the other hand, when the vehicle 1 is stopped, the CVT controller 61 puts the lockup clutch 34 in a non-engaged state in order to prevent engine stall. Then, when the driver's intention to start is detected, the lockup clutch 34 starts to be engaged when the speed ratio is small. Therefore, as shown in the third stage from the top of FIG. 3, the turbine rotational speed Nt rises before the timing t2 and gradually increases, and coincides with the engine rotational speed Ne at the timing t8 (the lock clutch 34). Is fully concluded). The engine rotation speed Ne when the lockup clutch is engaged is settled at a position slightly lower than the target rotation speed tNe (= tNe1). The reason why the CVT controller 61 fastens the lockup clutch 34 at the time of starting the vehicle is that the fuel fastness is better when the lockup clutch 34 is fastened than when the lockup clutch 34 is kept open.

Now, since the actual engine speed overshoots across the target speed tNe at the timing of t3, ideally, the command torque capacity of the lockup clutch 34 should be suddenly increased from the timing t3. This case (ideal case) is shown in the second row from the top in FIG. This is because, by increasing the command torque capacity of the lockup clutch 34 from the timing t3, the transmission torque of the torque converter 31 having a torque increasing action decreases by the increase of the transmission torque of the lockup clutch 34, and as a result, the torque The total value of the transmission torque of converter 31 and lockup clutch 34 is smaller than the transmission torque when only torque converter 31 is transmitted, the peak value of acceleration is suppressed, and engine speed Ne is exceeded from timing t3. This is because the chute can be suppressed. Further, by increasing the command torque capacity of the lockup clutch 34 from the timing t3, the completion of the engagement of the lockup clutch 34 is advanced from the timing t8 to the timing t7.

However, the command torque capacity of the lockup clutch 34 actually rises only from timing t4 that is delayed from timing t3. This is because there is a delay from when the CVT controller 61 issues an engagement command to the lockup clutch engagement means until the lockup clutch 34 actually responds (engagement delay of the lockup clutch 34). That is, the lock-up clutch engagement means includes a piston, hydraulic oil supply means, a control valve that can adjust the supply amount of hydraulic oil to the piston, and the like (not shown). When the control valve is opened in response to a fastening command from the CVT controller 61, hydraulic oil having a constant pressure is supplied from the hydraulic oil supply means to the piston attached to the turbine runner 33. The piston is extended by the supply of the hydraulic oil, and the extended piston is pressed against the converter cover. As a result, the input shaft (converter cover) and the output shaft (turbine runner) are directly engaged (the lock-up clutch 34 is engaged). In this case, the time until the lockup clutch 34 is engaged is determined by the opening of the control valve, and the lockup clutch 34 is quickly engaged as the opening of the control valve is increased. Since the lock-up clutch 34 is driven by the supply of hydraulic oil to the piston, even if the engagement command is issued at t3 when the engine rotation speed Ne crosses the target rotation speed tNe, there is a delay until the command torque capacity rises (from t3 to t4) This occurs.

Thus, if there is a delay in engagement of the lockup clutch 34, the engine rotational speed Ne overshoots across the target rotational speed tNe and increases to a considerably high rotational speed during the engagement delay of the lockup clutch 34. . Then, as indicated by the one-dot chain line in the second stage from the top in FIG. 3, when the command torque capacity of the lockup clutch 34 finally increases suddenly from the timing t4, the one-dot chain line in the third stage from the top in FIG. As shown in FIG. 8, the engine rotational speed Ne drops rapidly from the timing t4 as the command torque capacity increases. If there is a sudden drop in the engine speed Ne from the timing t4, a shock is generated, which causes a problem that a natural driving feeling cannot be provided to the driver.

In the case of normal control, the CVT controller 61 performs control as indicated by a broken line in the second stage from the top of FIG. 3 in order to avoid such a sudden drop in the engine speed Ne from the timing t4. That is, even if the timing for increasing the command torque capacity is the same timing t4, the command torque capacity of the lockup clutch 34 is increased by making the gradient of the initial increase gentle. However, when the slope of the initial increase is moderated and the command torque capacity of the lockup clutch 34 is increased, the engine rotational speed Ne becomes higher than the target rotational speed tNe as indicated by the broken line in the third stage from the top of FIG. It will be quite expensive.

It should be noted that there is a response delay until the command torque capacity of the lockup clutch 34 increases at timing t4 after the driver's intention to start is detected at timing t3 as described above. That is, as an oil pump for supplying hydraulic oil to the CVT 41, an oil pump that does not have a large discharge amount may be used for cost reduction. In this case, an increase in the command torque capacity of the lockup clutch 34 is delayed due to a delay in the pressure of the hydraulic oil supplied to the piston constituting the lockup clutch fastening means. Alternatively, as an oil pump for supplying hydraulic oil to the CVT 41, there is an oil pump that uses an oil pump with a large discharge amount, but in this case, a priority order in which the hydraulic oil is used is determined. For example, hydraulic oil is preferentially supplied to the frictional engagement elements for shifting, and the lockup clutch 34 is only turned in a slow order for fastening. In this case, an increase in the command torque capacity of the lockup clutch is delayed due to a delay in the timing at which the constant pressure hydraulic oil is supplied to the piston constituting the lockup clutch fastening means.

Therefore, in the first embodiment of the present invention, the CVT controller 61 that performs the engagement control of the lockup clutch 34 when the vehicle starts and the engine controller 21 that performs the engine control perform coordinated control. That is, as shown in FIG. 1, the CVT controller 61 (torque down command means) outputs a torque down command to the engine controller 21 so that the engine torque does not exceed the upper limit torque command value Td requested by the CVT 41. Then, the engine controller 21 (torque down control means) that receives the torque down command performs the following torque down control. That is, when the basic engine torque Te0 (engine torque) exceeds the upper limit torque command value Td, the engine controller 21 reduces the engine torque to the upper limit torque command value Td by retarding the ignition timing.

Also, the CVT controller 61 (upper limit torque command value setting means) sets the upper limit torque command value Td so that the maximum value of the engine speed that increases when the vehicle starts is close to the target speed. A method for setting the upper limit torque command value Td will be described with reference to FIG. FIG. 4 is a control block diagram for setting the upper limit torque command value. A target rotational speed calculation unit 71 to which the throttle valve opening TVO detected by the throttle sensor 13 is input calculates a target rotational speed tNe [rpm] of the engine 3 from the throttle valve opening TVO. The target rotational speed tNe takes a positive value (the target rotational speed NSET during idling) when the throttle valve opening TVO is zero, and is a value that increases as the throttle valve opening TVO increases.

The multiplier 72 to which the target rotational speed tNe is input calculates the square of the target rotational speed tNe.

The divider 73 to which the engine rotation speed Ne [rpm] and the turbine rotation speed Nt [rpm] detected by the input rotation speed sensor 62 are input, is obtained by dividing the turbine rotation speed Nt by the engine rotation speed Ne. The ratio e [nameless number] is calculated. The torque capacity coefficient calculation unit 74 (torque capacity coefficient calculation means) to which the speed ratio e is input calculates a torque capacity coefficient τ [10 −6 Nm / rpm 2] by searching a predetermined table from the speed ratio e. Since the characteristic of the torque capacity coefficient τ with respect to the speed ratio e is determined in advance according to the specification of the torque converter 31, the specification may be made into a table.

The multiplier 75 (torque converter transmission torque calculation means) to which the torque capacity coefficient τ and the square of the target rotational speed tNe are input multiplies them, that is, the transmission torque Ttc of the torque converter 31 by the following equation. [Nm] is calculated.

Ttc = τ · Ne2 (2)
The transmission torque Ttc thus obtained is a torque converter transmission torque for realizing the target rotational speed tNe.

The command torque capacity calculation unit 76 (command torque capacity calculation means) calculates a command torque capacity Tlu [Nm] of the lockup clutch 34. Here, the calculation of the command torque capacity Tlu of the lockup clutch 34 may be performed as follows. That is, when the opening degree of the control valve constituting the lock-up clutch fastening means is constant, the piston position (piston extension amount) is determined in proportion to the time after the control valve is opened. The command torque capacity is determined accordingly. For this reason, a table of command torque capacity of the lock-up clutch using the time since opening the control valve as a parameter is obtained in advance. Then, the command torque capacity Tlu of the lockup clutch is calculated by searching the above table from the time after opening the control valve.

The adder 77 (adding means) adds the torque converter transmission torque Ttc for realizing the target rotational speed tNe and the command torque capacity Tlu [Nm] of the lockup clutch, and uses the obtained sum as an upper limit torque command. Set as the value Td [Nm].

By setting the upper limit torque command value Td in this way, it is possible to avoid the engine rotational speed Ne from becoming less than the target rotational speed tNe while obtaining the acceleration feeling desired by the driver even when starting uphill. For example, even when the vehicle starts on an uphill, even when the target rotational speed tNe is the same, the vehicle acceleration decreases due to the slope of the uphill compared to when the vehicle starts on a flat road. For this reason, the degree of increase in the turbine rotational speed Nt is reduced, and the speed ratio e is reduced compared to when the vehicle starts on a flat road. At this time, it is assumed that an upper limit torque command value uniformly set based on the throttle valve opening TVO is given so as to obtain an acceleration desired by the driver when the vehicle starts on a flat road. In this case, there arises a problem that the engine rotational speed Ne becomes less than the target rotational speed tNe when the vehicle starts on the uphill by the difference between the torque capacity coefficient τ between the uphill and the flat road. On the other hand, according to the present embodiment, when going uphill, the speed ratio e becomes smaller than when starting a vehicle on a flat road, so the engine speed Ne is obtained while obtaining the acceleration feeling desired by the driver when starting uphill. Is less than the target rotational speed tNe.

The engine controller 21 to which the upper limit torque instruction value Td is sent from the CVT controller 61 performs torque down control. This will be described again with reference to FIG. In the second row from the top in FIG. 3, the change in the upper limit torque command value Td sent from the CVT controller 61 is shown in a two-dot chain line.

The engine controller 21 starts the torque-down control upon receiving the torque-down command from the CVT controller 61 at the timing t3 when the actual engine speed Ne basically crosses the target speed tNe. Since the command torque capacity Tlu of the lockup clutch 34 does not increase in the section from the timing t3 to the timing t4 (that is, Tlu = 0), only the transmission torque Ttc of the torque converter 31 is calculated. That is, in FIG. 4, since the turbine rotational speed Nt = 0 at the beginning of vehicle start, the speed ratio e becomes zero, and the product of the torque capacity coefficient τ when the speed ratio e is zero and the square of the engine rotational speed Ne at that time. The transmission torque Ttc of the torque converter 31 is calculated with a fixed value. Since the engine speed Ne changes in the section from the timing t3 to the timing t4, the transmission torque Ttc of the torque converter 31 actually changes in the section from the timing t3 to the timing t4. In the second stage, Ttc changes with a constant value in a simplified manner. Since the command torque capacity Tlu of the lockup clutch 34 increases linearly from timing t4, the upper limit torque command value Td, which is a value obtained by adding the command torque capacity Tlu to the transmission torque Ttc of the torque converter 31, is the command torque The capacitance Tlu increases with the same inclination as the inclination of increase (straight line). When the upper limit torque command value Td increases, the upper limit torque command value Td crosses the basic engine torque Te0 at timing t5.

As described above, when the upper limit torque command value Td changes below the basic engine torque Te0 in the section from the timing t3 to the timing t5, the engine controller 21 performs the timing from the timing t3 when the upper limit torque command value Td falls below the basic engine torque Te0. The engine torque is limited during the period up to t5. That is, in a section from timing t3 to timing t4, torque down control is performed in which the upper limit torque command value Td is used as the engine torque command value instead of the basic engine torque Te0. As a result, the hatched area shown in the second row from the top of FIG. 3 surrounded by the solid basic engine torque Te0 and the two-dot chain upper limit torque command value Td is the torque cut of the engine in this embodiment. . Then, since it is no longer necessary to limit the engine torque from timing t5, the CVT controller 61 ends the torque down command. In response to this, the engine controller 21 controls the engine using the basic engine torque Te0 as the engine torque command value (returns to normal control) from the timing of ending the torque down command.

Thereby, according to the present embodiment, the following effects are obtained. That is, in the section from the timing t3 to the timing t5, the increase in the engine rotational speed Ne is suppressed as shown by the two-dot chain line in the second stage from the top in FIG. In the meantime, the command torque capacity Tlu of the lockup clutch starts to increase rapidly from timing t4. In the present embodiment, even if the command torque capacity Tlu is increased steeply from the timing t4 as shown by the one-dot chain line in the second stage from the top in FIG. 3, the solid line in the third stage from the top in FIG. As can be seen, the increase (maximum value) of the engine rotational speed Ne can be suppressed and controlled near the target rotational speed tNe. Further, by increasing the command torque capacity Tlu with a steep slope from the timing t4, the lockup clutch 34 is engaged at the same timing t8 as in the case of the normal control, so that the fuel efficiency is not deteriorated. On the other hand, in the normal control, when the command torque capacity Tlu is increased at a steep slope from the timing t4 as shown by the one-dot chain line in the second stage from the top in FIG. 3, a sudden drop in engine speed Ne or a shock occurs. It was.

Note that the second stage from the top of FIG. 3 is intended to show how the torque down control is performed by the upper limit torque command value Td, so that the torque down control before timing t2 and after timing t5 is performed. In the not-shown section, the movement of the upper limit torque command value Td is roughly described. That is, before the timing t2, the upper limit torque command value Td is in a state of the constant value Td0, and is decreased from the timing t2. Immediately after the timing t5 when the torque-down control ends, the upper limit torque command value Td increases with the same slope as immediately before the timing t5, and after the timing t6, the upper limit torque command value Td returns to the constant value Td0. Therefore, the movement of the upper limit torque command value Td described in the second stage from the top in FIG. 3 does not coincide with the movement of the upper limit torque command value Td calculated by the flowchart described later.

The above-described control executed by the CVT controller 61 and the engine controller 21 will be described with reference to the flowcharts of FIGS.

The flowchart of FIG. 5 is for setting a start flag, and is executed by the CVT controller 61 at regular intervals (for example, every 10 ms). In steps S1 and S2, the CVT controller 61 determines whether or not a start operation has been performed this time, and whether or not a start operation has been performed last time. Whether or not the start operation has been performed may be performed based on changes in the accelerator opening APO and the throttle valve opening TVO sent from the engine controller 21. When the start operation is performed this time and the previous start operation is not performed, that is, when the start operation is performed for the first time this time, it is determined that the vehicle is starting. In this case, the CVT controller 61 sets a start flag (initially set to zero when the engine is started) = 1 in step S3. The state of the start flag = 1 is maintained after that. On the other hand, when the start operation is not performed at this time, or when the start operation is performed together with the previous time, the current process is terminated.

The flowchart in FIG. 6 is for setting a torque down command flag, and the CVT controller 61 executes the routine at a fixed time (for example, every 10 ms) following the flowchart in FIG. When setting the torque down command flag, the CVT controller 61 uses the throttle valve opening TVO and the basic engine torque Te0 transmitted from the engine controller 21.

In step S11, the CVT controller 61 determines whether or not the start flag (set according to the flowchart of FIG. 5) is 1. When the start flag = 0, the current process is terminated as it is.

When the start flag is 1 in step S11, it is determined that the start is in progress, and the CVT controller 61 executes the processing after step S12. In step S12, the CVT controller 61 determines whether or not the torque down end flag (initially set to zero when the engine is started) is 1. Here, the CVT controller 61 executes the process of step S13 on the assumption that the torque down end flag = 0. In step S13, the CVT controller 61 determines whether the torque down command flag (initially set to zero when the engine is started) is 1. Here, assuming that the torque down command flag = 0, the CVT controller 61 executes the process of step S14.

In step S14, the CVT controller 61 calculates a target rotational speed tNe [rpm] corresponding to the throttle valve opening TVO. The operation in step S14 is the same as that performed by the target rotation speed calculation unit 71 in FIG. Here, the throttle valve opening TVO is transmitted from the engine controller 21.

In step S15, the CVT controller 61 starts the torque down command by setting a value lower by the rotational speed corresponding to the delay of the torque down command from the target rotational speed tNe (corresponding to the section from t2 to t3 in FIG. 3). It is calculated as a determination rotational speed sNe [rpm]. In step S16, the CVT controller 61 compares the start determination rotational speed sNe with the actual engine rotational speed Ne. When the engine rotation speed Ne is less than the start determination rotation speed sNe, the CVT controller 61 determines that it is not the start timing of the torque down command and ends the current process as it is.

On the other hand, when the engine rotation speed Ne becomes equal to or higher than the start determination rotation speed sNe in step S16, the CVT controller 61 determines that it is the start timing of the torque down command. In this case, the CVT controller 61 sets a torque down command flag (initially set to zero when the engine is started) = 1 in step S17 in order to start (output) a torque down command.

Here, the reason for starting (outputting) the torque down command from a value (sNe) lower than the target rotational speed tNe by the rotational speed corresponding to the delay of the torque down command (corresponding to the period from t2 to t3). Is as follows. That is, when the driver depresses the accelerator pedal 22 by a certain amount for starting, the throttle valve opening increases at the timing t1 as shown in the uppermost stage of FIG. 3, and the predetermined value TVO1 is maintained from the timing t2. The CVT controller 61 calculates the target rotational speed tNe using the throttle valve opening TVO sent from the engine controller 21. From the timing when the throttle opening TVO becomes TVO1, the CVT controller 61 uses the predetermined value TVO1 to calculate tNe. There is a delay before is calculated. Further, the state of the torque down command flag (torque down command) is transmitted to the engine controller 21, and the torque down control is started at the timing when the torque down command flag is switched from zero to one. However, there is also a delay before the state of the torque down command flag is transmitted to the engine controller 21 and used in the flowchart of FIG. Thus, the torque down command is delayed by the amount of delay associated with the data reciprocating between the two

controllers

21 and 61 and the input / output of data. Therefore, the CVT controller 61 switches the torque down command flag from zero to 1 at an early timing (t2) in anticipation of the delay of the torque down command by calculating a start determination rotational speed sNe that is lower than the target rotational speed tNe. (Torque down command is issued). When the torque down command flag is transmitted to the engine controller 21, the torque down command flag is switched from zero to 1 at timing t3 as shown in the lowermost stage of FIG. Thus, the reason why the start determination rotational speed sNe is introduced on the CVT controller 61 side is to enable the engine controller 21 to start the torque-down control at the timing of t3.

In the present embodiment, the gradient of increase in the engine rotation speed Ne when the vehicle starts (that is, the gradient of increase in the engine rotation speed Ne from the timing t1 to the timing t2 in the third stage in FIG. 3) is substantially constant. Assume that there is. Actually, it is conceivable that the gradient of increase in the engine rotation speed Ne at the start of the vehicle changes. In this case, if the gradient of the increase in Ne of the engine rotation speed is larger (standing) than the gradient shown in the third stage from the top of FIG. 3, tNe−sNe is set to the third stage from the top of FIG. What is necessary is just to set larger than the case shown.

In step S18, the CVT controller 61 calculates the upper limit torque command value Td [Nm]. This content is described above with reference to FIG.

Since the torque down command flag is set to 1 in step S17, the CVT controller 61 proceeds from step S13 to step S19 in the subsequent calculation. In step S19, the CVT controller 61 calculates the upper limit torque command value Td in the same manner as in step S18. In step S20, the CVT controller 61 compares the upper limit torque command value Td with the basic engine torque Te0. Here, the basic engine torque Te0 is obtained from the engine controller 21 via CAN communication. When the upper limit torque command value Td is less than the basic engine torque Te0, the CVT controller 61 sets a torque down command flag = 1 (outputs a torque down command) in step S21. From the next time, as long as the upper limit torque command value Td is less than the basic engine torque Te0, the CVT controller 61 repeats the operation of step S21 (continues to issue a torque down command).

Eventually, when the upper limit torque command value Td becomes equal to or greater than the basic engine torque Te0 in step S20, the CVT controller 61 determines that it is time to end (or cancel) the torque down command. At this time, the CVT controller 61 executes steps S22, S23, and S24 in order to end the torque down command, and sets the torque down end flag = 1, the torque down command flag = 0, and the start flag = 0. Since the torque down end flag is set to 1 in step S22, the CVT controller 61 does not proceed from step S12 to step S13 in the subsequent calculation.

The CVT controller 61 transmits the torque-down command flag and the torque-down end flag set in this way as a torque-down command together with the upper limit torque command value Td calculated from FIG. 4 to the engine controller 21 via CAN communication (FIG. 1).

7 is for calculating the engine torque command value Te and the ignition timing command value ADV, and is executed by the engine controller 21 at regular intervals (for example, every 10 ms). When calculating Te and ADV, the engine controller 21 uses a torque down command flag, a torque down end flag, and an upper limit torque command value Td transmitted from the CVT controller 61 as a torque down command.

In step S31, the engine controller 21 calculates a basic engine torque Te0 [Nm] by searching a map having the contents shown in FIG. 8 from Qa based on the engine speed Ne and the intake air amount detected by the air flow meter 25. . As shown in FIG. 8, the basic engine torque Te0 increases as the intake air amount Qa increases under the condition where the engine rotational speed Ne is constant, and increases as the engine rotational speed Ne increases under the condition where the intake air amount Qa is constant. Value.

In step S32, the engine controller 21 calculates a basic ignition timing ADV0 [° BTDC] by searching a predetermined map from the engine speed Ne and the basic injection pulse width Tp [ms]. The basic ignition timing ADV0 is determined so that, for example, MBT can be obtained even if Ne and Tp are different. The basic injection pulse width Tp is a value determined from the engine speed Ne and the intake air amount Qa. When the fuel injection valve 7 is opened by the basic pulse width Tp, a predetermined amount of fuel is supplied to the intake port 5, and the stoichiometric air-fuel mixture is determined by the amount of fuel at this time and the amount of intake air flowing through the intake port. Will be obtained.

In step S33, the engine controller 21 determines whether the torque down command flag is 1 or not. This torque down command flag is sent from the CVT controller 61. As described above, the timing at which the engine controller 21 switches the torque down command flag from zero to 1 is delayed from the timing at which the CVT controller 61 switches the torque down command flag from zero to one. When the torque down command flag = 0, it is determined that the torque down command has not been issued yet. In this case, the engine controller 21 executes the processing of steps S41 and S42 to put the basic engine torque Te0 into the engine torque command value Te and the basic ignition timing ADV0 [° BTDC] into the ignition timing command value.

On the other hand, when the torque down command flag = 1, the engine controller 21 proceeds to step S34 to start the torque down control, and is constant after the torque down command flag becomes 1 (that is, after the torque down command is issued). Determine whether time has passed. Here, Steps S34, S43, and S44 are processes for dealing with a case where the engagement of the lockup clutch 34 is not started due to some trouble. As long as the engagement of the lock-up clutch 34 is started, the processing after step S35 is executed before the fixed time elapses. As long as the engagement of the lockup clutch 34 is started, the upper limit torque command value Td coincides with the basic engine torque Te0 in the vicinity of the timing t5 in FIG. 3, so the end timing of the fixed time is set at a time slightly exceeding the timing t5. Keep it.

Here, it is assumed that there is no problem, that is, a certain time has not elapsed, the process proceeds to step S35, and the torque down end flag is checked. The torque down end flag is sent from the CVT controller 61. When the torque down end flag = 0, it is determined that the end timing of the torque down command has not come (the torque down command has not ended). At this time, the processing of step S36-38 (torque down control) is executed.

Specifically, first, in step S36, the engine controller 21 enters the upper limit torque command value Td into the engine torque command value Te. The upper limit torque command value Td is sent from the CVT controller 61. It should be noted that the engine torque is not limited to the upper limit torque command value Td just because the upper limit torque command value Td is entered in the engine torque command value Te. In practice, the engine torque is reduced to the upper limit torque command value Td by retarding the ignition timing described later.

In step S37, the engine controller 21 reads the engine torque command value Te into which the upper limit torque down command value Td has been entered. In step S38, the engine controller 21 calculates an ignition timing for reducing the engine torque to the engine torque command value Te, and sets the calculated ignition timing as an ignition timing command value ADV [° BTDC].

From the next time onward, as long as the torque down end flag = 0 in step S35, the engine controller 21 repeats the processing of steps S36-38 in order to continue the torque down control. After a while, when the torque down end flag is set to 1 in step S35, the engine controller 21 determines that the end timing of the torque down command has come (the torque down command has ended). At this time, the engine controller 21 executes the processes of steps S39 and S40 to end the torque reduction control, and sets the basic engine torque Te0 to the engine torque command value Te and the basic ignition timing ADV0 to the ignition timing command value ADV.

On the other hand, when a certain time has elapsed since the torque-down command flag becomes 1 in step S34, the engine controller 21 determines that the engagement of the lock-up clutch 34 has not been started for some reason, and terminates the torque-down control. The process of step S43 is executed. In step S43, the engine controller 21 sets a value obtained by adding the constant value ΔT to the previous engine torque command value Te as the current engine torque command value Te. The constant value ΔT is a value that determines the speed at which the engine torque is returned from the upper limit torque command value Td to the basic engine torque Te0, and is set in advance.

In step S44, the engine controller 21 compares the engine torque command value Te calculated in step S43 with the basic engine torque Te0. When the engine torque command value Te is less than the basic engine torque Te0, the engine controller 21 determines that it is not time to end the torque down control. At this time, the process of step S40 is executed to put the basic ignition timing ADV0 into the ignition timing command value ADV. As long as the engine torque command value Te is the basic engine torque Te0, the engine controller 21 repeats the process of step S40.

Eventually, when the engine torque command value Te becomes equal to or higher than the basic engine torque Te0, the engine controller 21 determines that the end timing of the torque reduction control has come. At this time, the engine controller 21 executes steps S39 and S40 in order to end the torque reduction control, and sets the basic engine torque Te0 to the engine torque command value Te and the basic ignition timing ADV0 to the ignition timing command value ADV.

As described above, the above steps S43 and S44 are based on the case where the lock-up clutch 34 has not been engaged. Therefore, even when a predetermined time has elapsed from the start of the torque-down control, the engine torque is basically set at a preset speed. The engine torque is returned to Te0.

In step S45, the engine controller 21 outputs the engine torque command value Te and the ignition timing command value ADV. In another flowchart (not shown) of the engine controller 21, the target intake air amount is calculated based on the engine torque command value Te. Further, the engine controller 21 generates a spark in the spark plug 8 by cutting off the primary side current of the ignition coil when the crank angle reaches the ignition timing command value ADV, and thereby the air-fuel mixture in the combustion chamber 6 is generated. Ignite.

In the flowchart of FIG. 7 described above, the torque is reduced by retarding the ignition timing, but the torque reduction method is not limited to this. For example, the torque can be reduced by cutting the fuel injection, reducing the intake air amount by reducing the opening of the electronic control throttle, or the like. In addition, when an alternator that extracts driving force from the crank pulley of the engine via a belt is provided, the same purpose as the torque control described above can be achieved by increasing the power generation load of the alternator and reducing the input torque of the transmission. it can.

Next, in the present embodiment, it is possible to facilitate the driver's accelerator pedal operation by suppressing acceleration particularly in the low accelerator opening range, and to easily realize an appropriate accelerator opening corresponding to the acceleration desired by the driver. It also has a different effect of being able to. This effect will be described with reference to FIG. In FIG. 2, the characteristics of the acceleration peak value Gp with respect to the accelerator opening APO in the case of the present embodiment are shown by being overlapped with a solid line. In normal control, as shown by the broken line in FIG. 2, the acceleration peak value Gp rises steeply in the low accelerator opening region near zero, so that the decomposition performance of the acceleration peak value with respect to the accelerator opening APO deteriorates, and the driver As described above, it is difficult to obtain the desired acceleration. On the other hand, in the present embodiment, as shown by the solid line in FIG. 2, the acceleration gradient of the acceleration peak value Gp is gentler in the low accelerator opening range near zero than in the case of normal control. Easy to operate. If the driver's accelerator pedal operation becomes easy, the accelerator pedal can be adjusted to the depression amount corresponding to the acceleration desired by the driver. The resolution performance of the acceleration peak value with respect to the accelerator opening APO is improved as compared with the case of normal control.

Further explanation. In order to obtain the acceleration peak value characteristic with respect to the accelerator opening APO as shown by the solid line in FIG. 2, the throttle valve opening is reduced to be smaller than the accelerator opening APO in the low accelerator opening range. A correction method is conceivable (see Japanese Patent Application Laid-Open No. 2006-125213). The method for negatively correcting the throttle valve opening (hereinafter simply referred to as “in the case of negative correction”) and this embodiment will be compared with reference to FIG. Here, FIG. 10 shows how the accelerator opening APO, the throttle valve opening TVO, the engine torque, and the vehicle acceleration change when the vehicle starts. The same parts as those in FIG. 3 are denoted by the same reference numerals. Note that the time scale on the horizontal axis is not the same as that in FIG. 3, but is larger than that in FIG.

Now, when the accelerator pedal is depressed by a certain amount at the timing t1 and the accelerator opening APO changes to the predetermined value APO1 at the timing t3, that is, when the accelerator opening APO changes almost stepwise, the change in the accelerator opening APO is changed. In response to this, the throttle valve opening TVO changes. That is, in the normal control and the present embodiment, as shown by the solid line in the second stage from the top in FIG. 10, the throttle valve opening TVO becomes larger than the timing t1 and settles to the predetermined value TVO1 at the timing t3.

On the other hand, in the case of negative correction, the throttle valve opening TVO is predetermined at a timing t11 before the timing t3 when the throttle valve opening settles to the predetermined value TVO1, as indicated by a broken line in the second stage from the top in FIG. It is once limited to a predetermined value TVO2 smaller than the value TVO1. The predetermined value TVO2 is maintained until the timing t12 when the acceleration after the timing t3 reaches a peak. After the acceleration reaches a peak at timing t12, the throttle valve opening TVO is gradually returned from the predetermined value TVO2 to the throttle valve opening TVO1 in the case of normal control. In the case of negative correction, such a response of the throttle valve opening TVO can suppress the acceleration peak value Gp as compared with the case of normal control, as indicated by a broken line at the bottom of FIG. is made of.

However, in the case of minus correction, the increase in acceleration in the section from timing t11 to timing t12 is also suppressed to be smaller than in the case of normal control as shown by the broken line in the lowermost stage of FIG. For this reason, the driver feels that the acceleration feeling is insufficient in the first half of the acceleration, and depresses the accelerator pedal 22. As a result, the acceleration desired by the driver may increase as a result, and the engine rotation speed Ne may increase beyond the target rotation speed tNe.

On the other hand, in the present embodiment, the change in the throttle valve opening TVO is the same as in the normal control as shown by the solid line in the second stage from the top of FIG. For this reason, the change (increase speed) of the engine torque is the same as in the case of the normal control until the timing t3 when the torque down command is started (issued) as shown by the solid line in the third stage from the top in FIG. . As a result, as shown by the one-dot chain line at the bottom of FIG. 10, the acceleration peak value Gp can be obtained without suppressing the rise of acceleration in the first half of acceleration from timing t11 to timing t12 as in the case of minus correction. It can be suppressed. In other words, until the timing t3, the throttle valve opening TVO and the ignition timing are not changed from the case of the normal control. As a result, it is possible to control the engine rotational speed Ne to near the target rotational speed tNe while suppressing the rising (maximum value) of the engine rotational speed Ne without slowing the initial rise of the acceleration.

In addition, even in the latter half of the acceleration from the timing t12, when minus correction is performed, the gradient of the engine torque increase is suppressed to the timing t8 as shown by the broken line in the third stage from the top of FIG. On the other hand, in the present embodiment, even in the latter half of the acceleration from the timing t12, the acceleration is larger than that in the case where the acceleration is negatively corrected as shown by the one-dot chain line in the lowermost stage of FIG. This is because the command torque capacity Tlu of the lock-up clutch 34 is rapidly increased after the torque-down command is started, and the torque-down command is terminated at t5 when the upper limit torque command value Td matches the basic engine torque Te0. In other words, in this embodiment, the engine torque is returned to the normal control at the timing t5 much earlier than t8, and from this the torque is output from the engine as much as possible from t5. As a result, it becomes possible to prevent a shortage of torque in the latter half of acceleration from t12, and the vehicle can be run efficiently.

Here, the operational effects of this embodiment will be described together.

In the present embodiment, it is assumed that the vehicle 1 has a power train 2 in which an engine 3 and a CVT 41 (automatic transmission) are connected via a torque converter 31 including a lock-up clutch 34. Then, the CVT controller 61 (torque down command means) issues a torque down command to the engine side so that the engine torque does not exceed the upper limit torque command value Td requested by the CVT 41. In addition, the CVT controller 61 (upper limit torque command value setting means) calculates the upper limit torque command value Td so that the maximum value of the engine speed that rises when the vehicle starts is within the target engine speed tNe. The engine controller 21 (torque down control means) receives the torque down command and performs torque down control so that the engine torque does not exceed the upper limit torque command value Td. According to the present embodiment, it is possible to suppress an unnecessary surging in which the engine rotational speed at the time of starting the vehicle overshoots across the target rotational speed tNe, and to improve the controllability of acceleration in the low accelerator opening range. Can do. As a result, it is possible to obtain a good driving feeling while improving fuel efficiency.

There may be a predetermined delay from when the CVT controller 61 (automatic transmission controller) issues a torque down command to when the engine controller 21 follows the command. In this case, if the torque down command is issued when the actual engine rotational speed reaches the target rotational speed tNe, the timing for issuing the torque down command is delayed by the above delay. As a result, the increase in the engine speed and the acceleration peak at the start of the vehicle cannot be appropriately suppressed by the delay. On the other hand, the present embodiment includes an engine controller 21 and a CVT controller 61 (automatic transmission controller). Further, the CVT controller 61 has a predetermined delay from when the torque down command is issued until the engine controller 21 follows the command. In this case, the CVT controller 61 (automatic transmission controller) as a torque down command means includes a target rotation speed calculation unit 71 (target rotation speed calculation means) that calculates a target rotation speed tNe based on the accelerator opening degree TVO. ing. Then, the start determination rotation speed sNe obtained by subtracting the predetermined delay from the calculated target rotation speed tNe is compared with the actual engine rotation speed Ne, and the actual engine rotation speed Ne is determined based on the comparison result as the start determination rotation speed. When sNe is reached, a torque down command is issued. As a result, even if there is a predetermined delay from when the CVT controller 61 issues a torque down command to when the engine controller 21 follows the command, a good acceleration response is obtained while suppressing the engine speed Ne from rising. be able to.

In the present embodiment, the vehicle 1 includes a lockup clutch fastening means for fastening the lockup clutch 34 when the vehicle starts. Further, there is a predetermined delay (t3-t5 in FIG. 3) from the timing when the driver's intention to start is detected until the command torque capacity of the lockup clutch 34 rises. The CVT controller 61 (automatic transmission control controller) as the upper limit torque command value setting means includes a torque capacity coefficient calculation unit 74, a multiplier 75, a command torque capacity calculation unit 76, and an adder 77. Composed. The torque capacity coefficient calculation unit 74 calculates the torque capacity coefficient τ of the torque converter 31 from the speed ratio e obtained by dividing the input rotation speed Nt of the CVT 41 (automatic transmission) by the engine rotation speed Ne. The multiplier 75 calculates a torque converter transmission torque Ttc for realizing the target rotational speed tNe based on the calculated torque capacity coefficient τ and the target rotational speed tNe. The command torque capacity calculation unit 76 calculates the command torque capacity Tlu of the lockup clutch 34. The adder 77 sets the sum of the calculated torque converter transmission torque Ttc and the calculated command torque capacity Tlu of the lockup clutch 34 as the upper limit torque command value Td. Accordingly, an appropriate torque upper limit value Td for controlling the engine rotation speed to the target rotation speed tNe can be set even if the vehicle weight or the road surface gradient is different.

In the present embodiment, after issuing the torque down command, the CVT controller 61 increases the upper limit torque command value Td in accordance with the increase in the command torque capacity Tlu of the lockup clutch, and the upper limit torque command value Td becomes the basic engine torque Te0. The torque down command is terminated at a timing that coincides with. As a result, the engine torque can be restored to the basic engine torque Te0 while increasing the command torque capacity Tlu of the lockup clutch, so that rapid changes in acceleration and engine speed after the acceleration peak can be prevented. it can.

(Second Embodiment)
This embodiment is different from the first embodiment described above in part of the calculation method of the engine torque command value Te. The flowchart in FIG. 9 is for calculating the engine torque command value Te in the present embodiment, and is executed by the engine controller 21 at regular intervals (for example, every 10 ms). When calculating the engine torque command value Te, the engine controller 21 uses a torque down command flag, a torque down end flag, and an upper limit torque command value Td transmitted as a torque down command from the CVT controller 61.

Hereinafter, the difference from the flowchart in FIG. 7 will be mainly described.

In step S90, the engine controller 21 calculates a basic engine torque Te0. The calculation method is the same as step S31 in FIG.

In step S91, the engine controller 21 determines whether the torque down command flag is 1 as in step S33 of FIG. When the torque down command flag = 0, the engine controller 21 puts the basic engine torque Te0 into the engine torque command value Te in step S100. On the other hand, if the torque down command flag = 1, the engine controller 21 determines in step S92 whether or not a certain time has elapsed since the torque down command flag becomes 1 (that is, after the torque down command is issued). Determine.

If the predetermined time has elapsed, the engine controller 21 executes a process of step S102 described later. On the other hand, if the predetermined time has not elapsed, the engine controller 21 executes the process of step S93. In addition, the processing content of step S91 and step S92 is the same as that of step S33 and step S34 of FIG.

In step S93, the engine controller 21 determines whether the torque down end flag is 1 as in step S35 of FIG. If the torque down end flag is 1, the engine controller 21 executes the process of step S100. On the other hand, when the torque down end flag is not 1, the engine controller 21 executes the process of step S94.

In step S94, the engine controller 21 calculates a transmission strength upper limit torque Tk. The transmission strength upper limit torque Tk is an upper limit value of engine torque that the CVT 41 can withstand by design. Specifically, the calculation is performed by searching a predetermined map (not shown) from the input rotation speed of the CVT 41 and the gear ratio.

In step S95, the engine controller 21 determines whether or not the upper limit torque command value Td is smaller than the transmission strength upper limit torque Tk. If the upper limit torque command value Td is greater than or equal to the transmission strength upper limit torque Tk, the engine controller 21 enters the transmission strength upper limit torque Tk into the engine torque command value Te in step S101. On the other hand, when the upper limit torque command value Td is smaller than the transmission strength upper limit torque Tk, the engine controller 21 executes the process of step S96.

In step S96, the engine controller 21 calculates the expected acceleration lower limit torque Tg. The expected acceleration lower limit torque Tg is a torque necessary for realizing the minimum acceleration that can be expected from the vehicle speed VSP and the accelerator opening APO. The expected acceleration lower limit torque Tg is calculated by searching a predetermined map from the vehicle speed VSP and the accelerator opening APO.

In step S97, the engine controller 21 determines whether or not the upper limit torque command value Td is larger than the expected acceleration lower limit torque Tg. If the upper limit torque command value Td is less than or equal to the expected acceleration lower limit torque Tg, the engine controller 21 puts the expected acceleration lower limit torque Tg into the engine torque command value Te in step S102. On the other hand, when the upper limit torque command value Td is larger than the expected acceleration lower limit torque Tg, the engine controller 21 enters the upper limit torque command value Td into the engine torque command value Te in step S98.

In step S99, the engine controller 21 outputs an engine torque command value Te. In another flowchart (not shown) of the engine controller 21, the target intake air amount and the ignition timing are calculated based on the engine torque command value Te.

On the other hand, when a predetermined time has elapsed since the torque-down command flag became 1 in step S92, the engine controller 21 executes the processes of steps S103 to S105. The processing of steps S103-S105 corresponds to the processing of steps S43-S44-S39 in FIG.

Next, the function and effect of this embodiment will be described.

In this embodiment, in addition to the same effects as those of the first embodiment, the following effects can be obtained.

In the present embodiment, after issuing the torque down command, the CVT controller 61 compares the upper limit torque command value Td with the transmission strength upper limit torque Tk, and sets the smaller one as the upper limit torque command value Td. . Thereby, durability of CVT41 is securable.

In the present embodiment, after the CVT controller 61 issues the torque down command, the expected acceleration lower limit torque (which is necessary for realizing the upper limit torque command value Td and the lower limit acceleration expected from the vehicle speed and the accelerator opening degree). The expected acceleration lower limit torque Tg) is compared with the magnitude of the upper limit torque command value Td. Thereby, since the acceleration according to the driver's accelerator pedal operation is obtained, it is possible to prevent the driver from feeling uncomfortable.

In the above embodiments, the case where the drive source is the gasoline engine 3 has been described. However, the present invention is not limited to this. For example, the drive source may be a diesel engine or a motor / generator, or a combination of an engine and a motor / generator. For example, when the drive source is a diesel engine, the same purpose as the torque down control described above can be achieved by executing a fuel injection cut or a reduction in the intake air amount in accordance with a torque down command. When the drive source is a motor / generator, the same purpose as the torque down control described above can be achieved by increasing the power generation load of the motor / generator according to the torque down command.

The embodiment of the present invention has been described above. However, the above embodiment only shows a part of application examples of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above embodiment. Absent.

This application claims priority based on Japanese Patent Application No. 2014-35780 filed with the Japan Patent Office on February 26, 2014, the entire contents of which are incorporated herein by reference.

Claims

In a vehicle drive source control device for controlling the drive source of a vehicle having a power train in which a drive source and an automatic transmission are connected via a torque converter having a lock-up clutch,
Upper limit torque command value setting means for setting the upper limit torque command value required by the automatic transmission so that the drive source rotational speed that rises as the vehicle starts is less than or equal to the target rotational speed of the drive source;
Torque down command means for issuing a torque down command for preventing the drive source torque from exceeding the upper limit torque command value;
Torque down control means for receiving the torque down command and performing torque down control of the drive source so that the drive source torque does not exceed the upper limit torque command value;
A vehicle drive source control device.
In the vehicle drive source control device according to claim 1,
A drive source controller for controlling the drive source;
An automatic transmission controller for controlling the automatic transmission;
Further comprising
There is a predetermined delay from when the automatic transmission controller issues the torque down command until the drive source controller starts the torque down control,
The automatic transmission controller as the torque down command means includes target rotation speed calculation means for calculating the target rotation speed based on the accelerator opening,
The start determination rotation speed, which is a value obtained by subtracting the predetermined delay from the calculated target rotation speed, is compared with the actual drive source rotation speed. From the comparison result, the actual drive source rotation speed becomes the start determination rotation speed. A vehicle drive source control device that issues the torque down command when it reaches the vehicle.
The vehicle drive source control device according to claim 2,
Lockup clutch fastening means for fastening the lockup clutch when the vehicle starts,
There is a predetermined delay from the timing when the driver's intention to start is detected until the command torque capacity of the lockup clutch rises,
The automatic transmission controller as the upper limit torque command value setting means,
Torque capacity coefficient calculating means for calculating a torque capacity coefficient of the torque converter from a speed ratio obtained by dividing the input rotational speed of the automatic transmission by the drive source rotational speed;
Torque converter transmission torque calculation means for calculating torque converter transmission torque for realizing the target rotation speed based on the calculated torque capacity coefficient and the target rotation speed;
Command torque capacity calculating means for calculating the command torque capacity;
A drive source control device for a vehicle, comprising: an adding means having an upper limit torque command value as a total value of the calculated torque converter transmission torque and the calculated command torque capacity.
In the vehicle drive source control device according to any one of claims 1 to 3,
After issuing the torque down command, the vehicle increases the upper limit torque command value in accordance with the increase in the command torque capacity, and ends the torque down command at a timing when the upper limit torque command value matches the basic drive source torque. Drive source control device.
In the vehicle drive source control device according to any one of claims 1 to 4,
After issuing the torque down command, the upper limit torque command value is compared with the transmission strength upper limit torque determined from the design strength of the automatic transmission, and the smaller one is set as the upper limit torque command value. A vehicle drive source control device.
In the vehicle drive source control device according to any one of claims 1 to 5,
After issuing the torque down command, the smaller one of the upper limit torque command value and the expected acceleration lower limit torque required to realize the lower limit acceleration expected from the vehicle speed and the accelerator opening. A drive source control apparatus for a vehicle that sets the upper limit torque command value.
In the vehicle drive source control device according to any one of claims 1 to 6,
The drive source is a vehicle drive source control device including at least one of an internal combustion engine and an electric motor.
In the vehicle drive source control device according to claim 7,
The drive source is an internal combustion engine;
After the torque down command is issued, the drive source controller reduces the torque of the internal combustion engine by reducing the ignition timing retard, fuel injection cut, or intake air amount of the internal combustion engine. .
In the vehicle drive source control device according to claim 7,
The drive source is an internal combustion engine;
After issuing the torque down command, the drive source controller increases the power generation load of the alternator taking out the driving force from the internal combustion engine or the power generation load of the motor / generator for driving the vehicle to increase the input of the automatic transmission. A drive source control device for a vehicle that reduces torque.
In a vehicle drive source control method for controlling a drive source of a vehicle having a power train in which a drive source and an automatic transmission are connected via a torque converter having a lock-up clutch,
An upper limit torque command value required by the automatic transmission is set so that the drive source rotational speed that rises as the vehicle starts is within the target rotational speed of the drive source,
A torque down command is issued so that the drive source torque does not exceed the upper limit torque command value,
A vehicle drive source control method for performing torque down control so that the drive source torque does not exceed the upper limit torque command value in response to the torque down command.