JP2006125213A - Engine control device for power train - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control throttle opening of an engine to reduce wasteful work consumed by a torque converter at the time of vehicle start in a power train of a vehicle in which an automatic transmission and the engine are drivably connected via the torque converter. <P>SOLUTION: At first, it is confirmed that vehicle is at a stop under a condition where an accelerator pedal 3 is not pressed at the time around t0. Pre-Gp throttle control maintaining throttle valve 4 is executed to make throttle opening smaller than throttle opening corresponding to accelerator opening, if accelerator opening increases after time t1. Post-Gp throttle control gradually opening throttle opening of the throttle valve 4 is executed to be converged to regular throttle control (broken line) corresponding to accelerator opening as indicated with solid line, if acceleration peak value Gp is detected at the subsquent time t2. Throttle opening (solid line) of the throttle valve 4 returns to regular throttle opening (broken line) at the subsquent time t3, and this control is completed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to control of a power train in which an automatic transmission such as a continuously variable transmission such as a V-belt system or a stepped automatic transmission and an engine composed of an internal combustion engine are drive-coupled via a torque converter. is there.

  In a vehicle using an automatic transmission that changes speed according to a driver's accelerator pedal operation and vehicle speed, an engine and an automatic transmission are connected via a torque converter to obtain a torque increasing action and a rotational difference absorbing action when the vehicle starts. It is common to drive-couple. In the torque converter, the larger the rotational difference between the torque converter inlet rotational speed inputted from the engine side and the torque converter outlet rotational speed outputted to the automatic transmission side, the greater the torque increasing action, but the torque increasing action becomes larger. Part of the engine output is converted into heat without being transmitted to the automatic transmission, increasing the amount of wasted work and reducing the transmission efficiency of the torque converter.

In particular, when the vehicle starts, the torque increasing action is most required. As the amount of heat to be converted increases, the amount of waste work increases, the transmission efficiency of the torque converter decreases, and the fuel consumption rate deteriorates. In addition, with the recent increase in engine displacement, improvement in fuel efficiency has become an issue. Perform control to limit the throttle opening of the engine so that it is less than the accelerator pedal operation according to the rotational difference of the torque converter or according to the speed ratio obtained by dividing the torque converter outlet rotational speed by the torque converter inlet rotational speed Conventionally, the inventions described in Patent Document 1 and Patent Document 2 are known as inventions for reducing fuel consumption.
The invention described in Patent Document 1 includes an electronically controlled throttle valve type engine, determines an acceleration state from an accelerator pedal operation, and restricts the throttle opening to a predetermined value if the speed ratio of the torque converter is less than the target speed ratio. Control.
In the invention described in Patent Document 2, the difference between the engine speed and the input shaft speed of the transmission is obtained as a slip amount. When the slip amount, that is, the rotational difference of the torque converter is larger than the determination value, the engine The throttle opening is controlled.
JP-A-5-79371 JP 7-293290 A

However, the conventional control device has the following problems. That is, in the throttle opening control disclosed in Patent Document 1, even if the throttle opening is the same, the speed ratio of the torque converter varies depending on the load on the vehicle such as the load weight and road gradient. Cannot always be optimally controlled.
For example, when starting from a state where the vehicle has stopped on a downhill, the rate of increase in vehicle speed is higher than when starting on a flat road, so the rate of increase in the torque converter speed ratio is also higher than when starting on a flat road. Become. In this case, if the torque converter speed ratio reaches a predetermined value early, the control for restricting the throttle opening is also released early, and the control for restricting the throttle opening cannot be continued.
On the other hand, when the vehicle starts from a state where it has stopped on an uphill, the rate of increase in the torque converter speed ratio is also low because the rate of increase in vehicle speed is lower than that on a flat road. It becomes low compared with. In this case, if the torque converter speed ratio reaches a predetermined value later, the control for limiting the throttle opening degree is continued despite the situation where the driving force is required.

Further, in the engine output control described in Patent Document 2, even if the rotational difference of the torque converter is the same, the transmission efficiency is different if the rotational speed of the torque converter outlet is different. Therefore, the throttle opening is limited according to the rotational difference of the torque converter. Then, the engine output is not always the optimal setting.
For example, the engine speed corresponding to the torque converter inlet rotational speed is 1000 [rpm] and the torque converter outlet rotational speed 0 [rpm], and the engine rotational speed is 2000 [rpm] and the torque converter outlet rotational speed. In the case of 1000 [rpm], the rotation difference is the same 1000 [rpm], but because the wasteful work amount that changes to heat, the work amount that the torque converter transmits, and the engine output that can be limited are different, The engine output cannot be properly controlled by calculating the throttle opening by map search using the rotation difference as a parameter.

  The present invention proposes an engine control device capable of controlling the throttle opening so as to optimally limit the engine output in accordance with the load on the vehicle and the transmission efficiency of the torque converter.

For this purpose, an engine control device for a power train according to the present invention comprises an engine whose output is controlled in accordance with a driver's accelerator operation and an automatic transmission via a torque converter. In the drive train of the vehicle, the torque converter converts the engine speed and engine torque output from the engine and inputs the input speed to the automatic transmission.
A speed ratio, which is a ratio between the engine speed and the input speed, is calculated when the vehicle starts, and the output is controlled based on the speed ratio and the engine speed. It is.

  According to the speed change control device of the present invention, the torque converter outlet torque input from the torque converter outlet (turbine) to the automatic transmission can be calculated based on the speed ratio of the torque converter and the engine speed. The engine output can be controlled based on the outlet torque, and the engine output can be controlled to be appropriately limited according to the load on the vehicle and the transmission efficiency of the torque converter.

Hereinafter, embodiments of the present invention will be described in detail based on examples shown in the drawings.
FIG. 1 shows a power train of a vehicle equipped with an engine control device at the start of the vehicle according to an embodiment of the present invention together with its control system. Reference numeral 1 denotes an engine, 2 denotes a transaxle, and the tandem coupling of the vehicle Configure the power train.
The output of the engine 1 is adjusted by a throttle valve 4 that increases in opening from fully closed to fully open in conjunction with the accelerator pedal 3 operated by the driver, and the engine output passes through the torque converter T / C and transaxle. 2 is input.

The opening degree of the throttle valve 4 of the engine 1 is controlled by the engine controller 6. Normally, the engine controller 6 reads the accelerator opening degree of the accelerator pedal 3, and the throttle valve 4 is adjusted so that the throttle opening degree matches the accelerator opening degree. A throttle opening command value is output to the throttle actuator 5 that opens and closes. However, when the vehicle starts, the engine control described later is executed to limit the throttle opening to be smaller than the accelerator opening.
Further, the engine controller 6 can also limit the engine torque to a predetermined value or less for improving fuel efficiency when starting the vehicle by controlling the ignition timing of the engine 1.

  The engine controller 6 is not dedicated to throttle opening control and ignition timing control at the time of starting the vehicle, but performs normal engine control such as fuel injection amount control. A signal from the throttle opening sensor 7 for detecting the throttle opening TVO of the throttle valve 4 and a signal from the engine rotation sensor 8 for detecting the engine speed Ne of the engine 1 are inputted, and usually these throttle opening A normal target engine torque Teo corresponding to the vehicle operating state such as TVO and engine speed Ne is obtained, and engine output control including fuel injection amount control and ignition timing control is performed so as to achieve this.

As shown in FIG. 1, the transaxle 2 includes a forward / reverse switching mechanism 2a on the engine side, a belt-type continuously variable automatic transmission 2b with a belt spanned between two movable pulleys, and a differential gear on the drive shaft 9 side. The device 2c is arranged and these are drivingly coupled,
The engine output input to the transaxle 2 via the torque converter T / C is transmitted to the drive wheels 10 on the left and right sides via the drive shaft 9.
The belt-type continuously variable automatic transmission 2b does not require a driver's shift operation, and automatically shifts according to the vehicle operating state such as the throttle opening TVO and the engine speed Ne.
In addition to the present embodiment, the transaxle 2 may include a toroidal continuously variable automatic transmission or a stepped automatic transmission combined with a planetary gear mechanism.

  The selected transmission ratio of the transaxle 2 is determined by the transmission controller 15, and the transmission controller 15 is connected to the sensors 7 and 8 via the engine controller 6 in order to calculate the optimum target transmission ratio according to the vehicle operating state. In addition to inputting the throttle opening (TVO) signal and engine speed (Ne) signal from the engine, the engine controller 6 inputs the signal related to the actual engine torque (Te) and the target engine torque (Teo) obtained from the internal information. Furthermore, a signal from the input rotation sensor 16 for detecting the input rotation speed Nt input to the transaxle 2 from the engine side and an output rotation speed No output from the transaxle 2 to the drive shaft 9 side are detected. The signal from the output rotation sensor 17 is input.

  The transmission controller 15 calculates a target gear ratio by executing a well-known control program (not shown) based on the above-described input information, and controls the shift of the transaxle 2 so as to select the target gear ratio. .

  By the way, in this embodiment, when the vehicle starts from the stop state, the engine control that contributes to the improvement of fuel consumption at the time of starting is performed as shown in FIG. 3 by executing the control program shown in FIG.

First, the outline of this control will be described along the control program shown in FIG. 2, and the effect of this control will be described along with FIG.
In the control program of FIG. 2 executed by the engine controller 6 when the vehicle starts, first, in step S1, the accelerator opening degree of the accelerator pedal 3 and the output rotation speed (No) signal from the sensor 17 via the transmission controller 15 are transmitted. Is read, and it is determined whether or not the accelerator opening is 0 and the output speed No is 0, that is, whether or not the vehicle is stopped in a state where the accelerator pedal 3 is not depressed.

If the accelerator opening is not 0 or the vehicle is not stopped (No), steps S2 to 5 are skipped and the process proceeds to step S6, and the throttle valve 4 is opened as it is with the throttle opening TVO corresponding to the accelerator opening. Perform normal throttle control.
On the other hand, if the accelerator opening is 0 and the vehicle is stopped (Yes), the process proceeds to step S2, and engine control is performed to restrict the throttle opening TVO to be smaller than the accelerator opening. .

  After executing the engine control in step S2, the process proceeds to step S3, and it is determined whether or not the peak value of the longitudinal acceleration is detected. If not detected (No), the process returns to step S2 to continue engine control when the vehicle starts. That is, until the acceleration peak value Gp is detected, the pre-Gp throttle control for maintaining the limited throttle opening is executed.

  If the acceleration peak value Gp is detected in step S3 (Yes), the process proceeds to step S4, and engine control is executed so that the throttle opening TVO smaller than the accelerator opening is changed to normal throttle control. This engine control is hereinafter referred to as throttle control after Gp.

  After executing the engine control in step S4, the process proceeds to step S5, and it is determined whether or not the normal throttle control is restored. If it still does not return (No), return to step S4 and continue this engine control. In other words, this post-Gp throttle control is executed until it is determined that the vehicle has returned.

  If it is determined in step S5 that the normal throttle control described above has been restored (Yes), the process proceeds to step S6, the normal throttle control is executed, and this control program is terminated.

  FIG. 3 shows the vehicle speed realized by increasing the accelerator opening, the throttle opening of the throttle valve 4, the engine rotational speed Ne corresponding to the torque converter inlet rotational speed, and the input corresponding to the torque converter outlet rotational speed. This is a time chart showing the rotational speed Nt, the torque converter speed ratio Nt / Ne obtained by dividing the rotational speed at the inlet of the torque converter by the rotational speed at the outlet of the torque converter, and the acceleration G in the vehicle longitudinal direction. The solid line indicates the case of this control. . For comparison, a case where only normal throttle control is performed is indicated by a broken line.

First, at time t0, the vehicle stops and the accelerator opening is zero. When the driver starts depressing the accelerator pedal 3 at the subsequent time t1, the accelerator opening increases as shown in the upper part of FIG. As the accelerator opening increases, the throttle opening also increases. However, in this control, as explained in steps S2 and S4, the throttle opening is negatively corrected so as to be closed with respect to the accelerator opening. As shown in the middle part of FIG. 3, the throttle opening is set lower than when only normal throttle opening control is performed (dotted line). That is, in the case of this control, the throttle opening TVO that seems to be closed is maintained so as to maintain a constant value after time t1 until t2, and after time t2, the throttle opening TVO is gradually increased, and finally the time Set to match the normal throttle opening at t3.
At time t2, as shown in the lower part of FIG. 3, the acceleration G in the vehicle front-rear direction shows the peak value Gp.

Further, as shown in the middle part of FIG. 3, the engine speed Ne is also lower than when only normal throttle opening control is performed (dotted line), increases at a constant gradient until time t2, and gradually increases after time t2. It increases and coincides with the engine speed (dotted line) at the normal throttle opening at time t3.
The torque converter outlet rotational speed Nt increases with a substantially constant gradient in the case of the main control indicated by the solid line, although slightly lower than the case where only the normal throttle opening control indicated by the dotted line is performed.
Therefore, as shown in the upper part of FIG. 3, the vehicle speed also increases at a substantially constant gradient with the same characteristics as the torque converter outlet rotational speed Nt.

  The speed ratio Nt / Ne is slightly larger than the case where the main control indicated by the solid line performs only normal throttle opening control (dotted line). This is because the engine speed Ne corresponding to the denominator of the speed ratio Nt / Ne is set low as described above.

  Thus, in this control, as shown in the lower part of FIG. 3, the acceleration peak Gp indicated by the solid line is smaller than when only normal throttle opening control is performed (dotted line), and the passenger feels The abrupt feeling can be alleviated.

Next, the throttle control of the present invention will be described more specifically.
In the pre-Gp throttle control executed in step S2, the engine controller 6 refers to the target engine torque correction map shown in FIG. 4 and corrects or increases the engine torque to the decreasing side (-1, 2) ( The throttle opening TVO is determined so that it is corrected to +1). The engine torque correction map of FIG. 4 illustrates the case where the accelerator opening is 2/8. In the case of other accelerator openings, an engine torque correction map corresponding to the accelerator opening is separately calculated. At any accelerator opening, the horizontal axis represents the speed ratio e of the torque converter T / C and the vertical axis. The axis indicates the engine speed Ne. The target engine torque Teo is negatively corrected as the engine speed Ne is larger and the speed ratio e is smaller.
When the vehicle starts, since the speed ratio e = 0 and the engine speed Ne is in the middle / high range, the torque Teo is negatively corrected with reference to FIG. Since the target engine torque Teo is negatively corrected, the throttle opening TVO is limited to be smaller than the accelerator opening.

In the target engine torque correction map for each accelerator opening, first, a target torque converter outlet torque described later is plotted in a characteristic diagram of the torque converter outlet torque shown in FIG. 8, and then this is shown in FIG. The plot converted into the figure and plotted is the target torque converter inlet torque (target engine torque). That is, since the torque converter inlet torque is equal to the engine torque, the target engine torque correction map can be obtained from the characteristic diagram of the torque converter inlet torque.
A characteristic diagram of torque converter outlet torque will be described. The relationship between the engine torque Te corresponding to the torque converter inlet torque and the engine speed is expressed by the following equation.
Te = τ · Ne ² (1)
τ is a capacity coefficient, and has a speed ratio e as a parameter as shown in the characteristic diagram of FIG.

The torque converter outlet torque Tt is expressed by the following equation.
Tt = t · τ · Ne ² (2)
t is a torque ratio (Tt / Te) indicating a ratio between the torque converter inlet torque and the torque converter outlet torque Tt, and has a speed ratio e as a parameter as shown in the characteristic diagram of FIG.

Therefore, the product t · τ of the capacity coefficient τ and the torque ratio t can be shown in the characteristic diagram of FIG. 7 having the speed ratio e as a parameter. According to the characteristic diagram of FIG. 7, t · τ decreases as the speed ratio e increases.
As a result, the torque converter outlet torque Tt also decreases as the speed ratio e increases. When the torque converter outlet torque Tt is displayed on the three-dimensional coordinate axis using the speed ratio e and the square of the engine speed Ne ² as parameters, it can be shown in the characteristic diagram of FIG. As shown in FIG. 8, the torque converter outlet torque Tt increases as the engine speed Ne increases and as the speed ratio e decreases.

  In converting the characteristic diagram of the torque converter outlet torque shown in FIG. 8 into the characteristic diagram of the torque converter inlet torque, it is necessary to obtain the target torque converter outlet torque and plot it in FIG. Therefore, a means for calculating the target torque converter outlet torque based on the accelerator opening will be described.

The block diagram of FIG. 10 shows an algorithm for calculating the target torque converter outlet torque. First, at 21, the target acceleration [m / s ² ] is calculated based on the read accelerator opening.
Next, the driving force [N] is calculated by multiplying the calculated target acceleration [m / s ² ] by 22 vehicle weights [kg].
Next, the axle torque [Nm] of the drive shaft 9 is calculated by multiplying the calculated driving force [N] by the tire moving radius [m] of the 23 wheels.
Next, the outlet torque [Nm] of the continuously variable transmission 2b is calculated by dividing the calculated axle torque [Nm] by the final reduction ratio of the 24 differential gear device 2c.
Next, the inlet torque [Nm] of the continuously variable transmission 2b is calculated by dividing the calculated exit torque [Nm] of the continuously variable transmission 2b by the lowest gear ratio that the 25 continuously variable transmission 2b can take. When the transaxle 2 includes a stepped automatic transmission, the gear ratio related to the first speed is divided here.
The calculated transmission inlet torque [Nm] is 26 target torque converter outlet torque [Nm].

  The target torque converter outlet torque [Nm] calculated in this way is plotted on the characteristic diagram of FIG. 8 representing the torque converter outlet torque Tt, and the relationship between the target speed ratio e and the engine speed Ne is obtained. For example, when the target torque converter outlet torque [Nm] is 150, the relationship between the speed ratio e and the engine speed Ne is plotted with a thick line in FIG.

  The characteristic diagram of FIG. 8 in which the target torque converter outlet torque [Nm] is plotted as described above is divided by the torque ratio t to be converted into a characteristic diagram representing the torque converter inlet torque shown in FIG. Since the torque converter inlet torque corresponds to the engine torque, the thick line in FIG. 8 is converted to the thick line in FIG. 11 indicating the target engine torque.

The curved surface indicated by the mesh in the characteristic diagram of FIG. 11 represents the torque converter inlet torque (engine torque) for each speed ratio e and engine speed Ne. Referring to FIG. 11, when the vehicle starts with a speed ratio e = 0 and the engine speed is higher than about 1000 rpm (idling state), the torque converter inlet torque (engine torque) is the target torque converter inlet torque (target torque). It turns out that it will become larger than an engine torque. Therefore, when the vehicle starts, the throttle opening TVO is corrected to the minus side so as to be closed with respect to the accelerator opening, and the engine torque is adjusted to the target engine torque.
When the target engine torque indicated by the thick line in FIG. 11 is cut out and displayed on a plane, it is as shown in FIG.
The relationship between the target speed ratio e and the engine speed Ne shown in FIG. 12 is equal to the relationship shown by the solid line in FIG. In this way, a target engine torque correction map for each accelerator opening can be obtained.

In the above-described pre-Gp throttle control executed in step S2 of FIG. 2, the throttle opening of the present control obtained as described above is maintained for each accelerator opening.
Next, in the above-described post-Gp throttle control executed in step S4 of FIG. 2, the throttle opening of this control is returned to the normal throttle opening. Thereby, the time chart of the accelerator opening and the throttle opening becomes as shown by the solid line in FIG. A broken line indicates a case of normal throttle control in which this control is not executed. FIG. 13 is an enlarged view of the time chart of FIG.

In the throttle control before Gp, when the driver starts depressing the accelerator pedal 3 at time t1 in FIG. 13, the accelerator opening increases stepwise, whereas the throttle opening TVO is opened at a stroke from time t1. Until the time t2, the opening is more closed than the normal opening without being opened to the appropriate opening.
In the throttle control after Gp, the throttle opening TVO is gradually opened after time t2, and is matched with the throttle opening corresponding to the accelerator opening shown by the broken line at time t3.

As shown by a solid line in FIG. 14, the corrected throttle opening for each accelerator opening is obtained from the desktop calculation and stored in advance in the engine controller 6, and the throttle control is executed by referring to FIG. May be.
In addition to FIG. 14, the corrected throttle opening corresponding to the accelerator opening is that the relationship between the accelerator opening (not shown) and the target engine speed (set value on a flat road or the like) and the speed ratio shown in FIG. The engine torque (torque converter inlet torque) at that time-engine speed characteristics and the engine speed-engine torque characteristic diagram (also referred to as engine performance curve) for each throttle opening are calculated by desktop calculation.

When executing the pre-Gp throttle control using the corrected throttle opening shown in FIG. 14, the trouble of obtaining the target engine torque correction map for each accelerator opening is omitted, and the pre-Gp throttle control is performed using FIG. 4 on a flat road. The effect can be expected to be almost the same as when executed.
However, since the rate of change in the load on the vehicle and the speed ratio varies depending on the inclination angle on the slope road, the engine output cannot be optimally limited by using the set value (FIG. 14) on the flat road.

On the other hand, in the throttle control before Gp of the present embodiment, the target torque converter outlet torque is calculated from the target acceleration corresponding to the accelerator opening as described above and as shown in FIG. 10, and the engine speed Ne and the speed shown in FIG. The target torque converter outlet torque in relation to the ratio e is converted into the target engine torque shown in FIGS. 11 and 12, and the target engine torque correction map shown in FIG. 4 is obtained for each accelerator opening, so that accurate throttle control is expected. Because it is a thing,
When the load is different, such as when starting on an uphill road or when starting on a downhill road, the engine output can be appropriately limited with reference to the target engine torque correction map shown in FIG. .

The effect of this control shown in FIG. 13 is shown by the solid line in FIG. A broken line indicates a case of normal throttle control in which this control is not executed. FIG. 15 is an enlarged view for easy viewing of the time chart shown in the lower half of FIG.
After time t1, the torque converter T / M cannot absorb the engine torque Te beyond the allowable amount of the torque capacity τ, and the surplus torque is used to increase the engine speed Ne. Along with this, the torque converter outlet torque Tt also increases in proportion to the square of the engine speed Ne ² as described above and equation (2). Therefore, the acceleration G increases. When the allowable amount of the torque capacity τ is balanced with the engine torque Te at time t2, the increase in the engine speed Ne is temporarily stopped as shown in the middle stage of FIG. At this time, the acceleration G of the vehicle reaches a peak value.

During this control, in the throttle control before Gp, when the driver starts depressing the accelerator pedal 3 at time t1 in FIG. 13, the accelerator opening increases stepwise, whereas the throttle opening TVO is detected at time t1. Until the time t2, the opening is more closed than the normal opening without being opened to the opening corresponding to the accelerator opening at once.
Accordingly, the acceleration G shown in the upper part of FIG. 15 rises gently, and a sudden feeling felt by the passenger can be prevented.

  As shown in the middle part of FIG. 15, after the time t2, the increase in the engine speed Ne stagnates or the engine speed Ne slightly increases. Since the vehicle speed continues to increase, the torque converter outlet rotational speed Nt continues to increase. As a result, the speed ratio e increases and the torque ratio t decreases. Therefore, the acceleration G decreases as shown in the upper part of FIG.

  During this control, in the throttle control after Gp, as shown in the lower part of FIG. 13, the throttle opening TVO is gradually increased from time t2 and finally set to coincide with the normal throttle opening at time t3. As shown in the upper part of FIG. 15, the accelerator pedal 3 is provided so that the acceleration G does not drop as in the case of the throttle opening with the throttle opening kept closed (thin line), and the driver covers the depression. It is possible to avoid operations such as stepping on.

  Further, the transmission efficiency η of the torque converter T / M is generally expressed as shown in FIG. 16, and as the speed ratio e decreases, the transmission efficiency η deteriorates. According to this control, the speed of the torque converter T / M Since the engine speed Ne is suppressed in a region where the ratio e is close to 0 and the transmission efficiency η is poor, deterioration of fuel consumption can be prevented.

  Further, as in this embodiment, as a further effect of correcting the throttle opening TVO to the minus side so as to be closed from the accelerator opening at the time of starting the vehicle, the accelerator operation of the driver can be facilitated and the accelerator pedal 3 can be operated. , It can be adjusted to the depression amount corresponding to the desired acceleration.

In describing this effect, first, the relationship between the accelerator opening and the acceleration peak value Gp will be described. The acceleration G is proportional to the torque converter outlet torque Tt. The torque converter outlet torque Tt is proportional to the engine torque Te and the torque ratio t from the above equations (1) and (2). The engine torque Te is proportional to the accelerator opening. Therefore, in the region where the torque ratio is large, the acceleration peak value Gp changes greatly even if the accelerator opening change amount is small.
This is clearly shown in the characteristic diagram showing the relationship between the accelerator opening and the acceleration peak value Gp shown in FIG. According to FIG. 9, when only the normal throttle control indicated by the dotted line is performed, the acceleration peak value rises steeply in the low opening region where the accelerator opening is close to zero.

  As a result, the decomposition performance of acceleration based on the accelerator opening is deteriorated, and it is difficult to obtain the desired acceleration G even if the driver increases or decreases the amount of depression of the accelerator pedal 3 in order to obtain the desired acceleration G. become. Therefore, in normal throttle control in which the throttle opening is controlled to match the accelerator opening, the accelerator fine operation becomes troublesome for the driver.

However, in this embodiment, when the vehicle starts, the throttle opening TVO is corrected to the minus side so as to be close to the accelerator opening, so the relationship between the accelerator opening and the acceleration peak value Gp is shown by a solid line in FIG. The slope is gentler than that of the normal throttle control (broken line).
Therefore, the driver's accelerator operation can be facilitated and the accelerator pedal 3 can be adjusted to the depression amount corresponding to the desired acceleration.

A method for detecting the acceleration peak value Gp will be described.
When attention is paid to the inlet rotational speed (engine rotational speed) and the outlet rotational speed of the torque converter T / M shown in FIGS. 3 and 15, these temporal changes are as shown in the upper part of FIG. When the difference Ne−Nt between the engine speed Ne corresponding to the torque converter inlet rotational speed and the torque converter outlet rotational speed Nt is calculated, the result is as shown in the middle stage of FIG.

Furthermore, when the time change rate Δ (Ne−Nt) of the difference Ne−Nt is calculated, the lower stage of FIG. 17 is obtained. According to this figure, it can be seen that the time change rate Δ (Ne−Nt) becomes 0 at time t4 slightly after time t2 when the acceleration peak value Gp appears. Therefore, the time change rate Δ (Ne−Nt) is monitored, and the appearance time t2 of the acceleration peak value Gp can be detected when it decreases to a predetermined value slightly larger than 0.
The reason why the predetermined value slightly larger than 0 is used as the threshold value is to avoid the inconvenience that if time 0 is set as the threshold value, the time t4 is detected and the detection is delayed with respect to the accurate appearance time t2.

  According to the above detection method, the rotational difference (Ne−Nt) is obtained from the torque converter outlet rotational speed Nt and the engine rotational speed Ne, and the vehicle starts to move forward and backward after starting based on the time change Δ (Ne−Nt) of the rotational difference. Since the time t2 at which the acceleration reaches a peak is detected, the time t2 can be quickly detected by a simple calculation method, and the switching from the throttle control before Gp to the throttle control after Gp can be performed quickly. .

Alternatively, as a method for detecting the acceleration peak value Gp, the algorithm shown in FIG. 18 may be executed, for example, every 50 ms.
In 31, the signal (input rotation speed Nt) from the sensor 16 is read. In 32, a signal (engine speed Ne) from the sensor 8 is read. By dividing these, the gear ratio e is calculated. In step 33, t · τ is obtained with reference to the characteristic diagram shown in FIG. In 34, the square of the engine speed Ne is calculated. The torque converter outlet torque is calculated by multiplying these by (t · τ · Ne ² ). In 35, the torque converter outlet torque of the previous value (50 ms before) one cycle before is stored. In 36, the torque converter outlet torque of the previous value (100 ms before) one cycle before is stored. In 37, a change amount Δ (t · τ · Ne ² ) between the current value and the previous previous value is calculated.

In 38, it is determined whether or not the change amount Δ (t · τ · Ne ² ) has become a predetermined value or less. If the value is less than the predetermined value, the process proceeds to 39 to switch to throttle control after Gp. If it is not less than the predetermined value, the routine proceeds to 40, where the pre-Gp throttle control is continued.
The predetermined value of 38 is a numerical value slightly larger than 0. This is to avoid the inconvenience that detection is delayed with respect to the accurate Gp appearance time t2 if 0 is set as the threshold value.

  According to the present embodiment, it is not necessary to separately provide a device such as a torque sensor, and it is possible to detect the appearance time of the acceleration peak value Gp using only the existing rotation detection sensors 8 and 16.

A method for converging the throttle opening TVO to the normal throttle opening in the post-Gp throttle control will be described with reference to FIG.
When the appearance time t2 of the acceleration peak value Gp is detected as described above, the vehicle speed VSP ₁ at the time t2 is read. The vehicle speed can be calculated from the output rotational speed No of the transaxle 2 detected by the output rotational speed sensor 17. Next, if the normal throttle opening is maintained, the vehicle speed VSP ₂ obtained at time t3 is calculated (broken line). Further, the normal throttle opening TVO ₂ and the throttle opening TVO ₁ in the Gp pre-throttle control are calculated by the engine controller 6.

These slightly set throttle opening TVO ₁ , normal throttle opening TVO ₂ , vehicle speed VSP ₁ when acceleration peak value Gp appears, and vehicle speed VSP when throttle opening TVO converges to the normal setting ₂ is used to calculate the target throttle opening TVO for the current vehicle speed VSP using the following equation.
TVO = TVO ₁ + (TVO ₂ −TVO ₁ ) ・ (VSP−VSP ₁ ) / (VSP ₂ −VSP ₁ ) (3)
Then, the engine controller 6 outputs a signal to the throttle actuator 5 so that the throttle opening of the throttle valve 4 follows the target throttle opening TVO of the expression (3).

As a result, the throttle opening TVO in the throttle control of the present embodiment is realized as shown by the solid line in FIG. 19 in relation to the vehicle speed VSP. First, the throttle control before Gp is executed until time t2 when the peak value Gp is detected, and the throttle opening TVO is held at TVO ₁ regardless of the vehicle speed VSP. Next, after time t2, throttle control after Gp is executed, and as the vehicle speed VSP increases, the throttle opening TVO increases with a constant gradient. Finally, after time t3, the throttle opening TVO returns to the normal throttle opening corresponding to the accelerator opening.

Therefore, in the present embodiment, since the throttle opening TVO is controlled based on the vehicle speed VSP corresponding to the torque converter outlet rotation speed, it is possible to execute appropriate control according to the load on the vehicle.
For example, under traveling conditions such as downhill where the load on the vehicle is small, this is realized as shown by a one-dot chain line instead of the solid line in FIG. 19, and the time for limiting the throttle opening TVO to TVO ₁ is lengthened, thereby improving fuel efficiency. Contribute.
Alternatively, under traveling conditions such as uphill where the load on the vehicle is large, the vehicle is realized as indicated by a two-dot chain line instead of the solid line in FIG. 19, and the convergence of the throttle opening TVO is accelerated and the drivability is improved.

The throttle control before Gp and the throttle control after Gp in the present embodiment will be described with reference to FIG. Note that FIG. 20 is common to FIG. 8 described above.
First, when the engine speed Ne reaches a mid-high speed range of approximately 1500 [rpm] or more after time t1 and the speed ratio e is a small value close to 0, throttle control before Gp is executed, and the engine characteristics are shown in FIG. It changes like 20 solid lines. When the torque converter outlet rotation speed (t · τ · Ne ² ) proportional to the acceleration G reaches the peak value at time t2, it decreases as shown by the solid line after time t2. Therefore, after time t2, throttle control after Gp is executed.

As described above, the post-Gp throttle control is a control in which the throttle opening gradually closes with respect to the accelerator opening to the throttle opening corresponding to the accelerator opening, so that time t2 to t3 is reached. The torque converter outlet rotational speed (t · τ · Ne ² ) changes as indicated by a solid line. As a result, the torque converter outlet rotational speed (t · τ · Ne ² ) with the throttle opening indicated by the thin line kept closed is changed to the normal throttle opening indicated by the broken line.

In the present embodiment, when the vehicle starts, the engine speed Ne and the input speed Nt are read, and the speed ratio e is calculated. Based on the speed ratio e and the engine speed Ne, FIG. Since the target engine torque correction map shown in FIG. 12 is calculated and the output of the engine 1 is controlled based on this map,
As indicated by the solid line in the lower part of the time chart in FIG. 3, the peak value Gp of the acceleration G that appears at time t2 when the vehicle starts can be made lower than the normal throttle control (broken line), and the suddenness felt by the passenger It is possible to reduce the feeling and improve the riding comfort of the vehicle. Further, since the throttle opening is corrected in accordance with the above-described equation (2) and the torque converter outlet torque Tt shown in FIG. 8, fine throttle control according to the running state at the time of vehicle start is possible.
The term “starting” as used in the claims refers to the case where the vehicle departs from the stop state, and the driver depresses the accelerator pedal 3 during the slow speed advance where the speed ratio is substantially 0, thereby increasing the longitudinal acceleration of the vehicle. Including cases.

Specifically, the target acceleration of the vehicle is determined based on the accelerator opening of the accelerator pedal 3 operated by the driver in 21 of FIG. 10, and the target torque converter outlet torque is calculated based on the target acceleration in 21 to 25. The map of the characteristic diagram of FIG. 8 is searched by using the calculated target torque converter outlet torque as a parameter to obtain the relationship between the speed ratio e and the engine speed Ne shown in FIG. 12 (corresponding to FIG. 4). Correct the target throttle opening from 4). Since the throttle opening is controlled to follow the corrected target throttle opening,
Throttle control suitable for the driving condition such as load on the vehicle can be executed.

  In addition, the throttle control is executed in consideration of the vehicle weight, the characteristics of the torque converter T / M (capacity coefficient, torque ratio), the final reduction ratio of the differential gear device 2c, etc. at the time of each calculation described above. Alternatively, by changing the design of some considerations, it is possible to easily design the start acceleration performance of the entire vehicle.

  This control to reduce the throttle opening is applicable not only when starting the vehicle, but also when the driver wants to accelerate and depresses the accelerator greatly while the torque converter is not directly connected and traveling in the low speed ratio range. It is possible to improve fuel efficiency and reduce suddenness.

In this embodiment, the time t2 at which the acceleration G reaches the peak value Gp is detected when the vehicle starts, and before the time t2, the target throttle opening is set to be smaller than the normal setting corresponding to the accelerator opening. Since the Gp pre-Gp throttle control is executed, and after the time t2, it is configured to execute the post-Gp throttle control to return the target throttle opening set to the small amount to a normal setting corresponding to the accelerator opening.
While the Gp pre-throttle control is being executed, the acceleration G rise is reduced, the sudden feeling is suppressed, and the ride performance and fuel efficiency are improved.
Further, during the execution of the throttle control after Gp, the acceleration G is prevented from dropping, and the driver does not increase the accelerator pedal 3 and the driving performance is improved.

  As a further effect, as shown in FIG. 9, the disassembly performance in the low and middle accelerator opening ranges is improved, and the fine operation of the accelerator pedal 3 which is troublesome for the driver becomes unnecessary.

Alternatively, the throttle opening correction at the times t1 to t2 may be determined using the search map shown in FIG. 14 instead of performing the above calculation. In this embodiment, the throttle opening is corrected to the most minus side at the accelerator opening 1/2, slightly corrected at a position other than the accelerator opening 1/2, and not corrected at the accelerator opening 0 and 8/8. This is determined as appropriate depending on the output characteristics of the engine 1 and the like.
By performing throttle opening correction using such a simple system, it is possible to omit the time required for calculation and to realize throttle control with high response with a simple configuration.

In this embodiment, as shown in FIG. 17, the rotational difference Ne-Nt between the engine rotational speed Ne and the torque converter outlet rotational speed Nt is obtained, and based on the time change Δ (Ne-Nt) of the rotational difference, Since it is characterized by detecting the time t2 when the acceleration G reaches the peak value Gp,
There is no need to provide a separate device such as a torque sensor, and the appearance time of the acceleration peak value Gp can be detected using only the existing rotation detection sensors 8 and 16, and the Gp appearance time can be quickly detected by a simple calculation method. t2 can be detected, and switching from the throttle control before Gp to the throttle control after Gp can be performed quickly.

Alternatively, as shown in FIG. 18, the torque converter outlet torque Tt expressed by the equation (2) is obtained based on the speed ratio e and the engine speed Ne, and the acceleration G is a peak value Gp based on the time change of the torque converter outlet torque Tt. By detecting the time t2 that reaches
There is no need to provide a separate device such as a torque sensor, and the appearance time of the acceleration peak value Gp can be detected using only the existing rotation detection sensors 8 and 16.

Further, in this embodiment, the throttle opening TVO ₁ with the closed feeling set by the throttle control before Gp is returned to the normal throttle opening TVO ₂ according to the increase in the vehicle speed based on the equation (3). From running
The engine output can be appropriately controlled in accordance with the operating state of the torque converter T / M and the load on the vehicle.

1 is a system diagram showing a power train of a vehicle including an engine control device according to an embodiment of the present invention together with its control system. 4 is a flowchart showing a control program executed for engine throttle control in the embodiment. It is an operation | movement time chart of the throttle control in the Example. It is a target engine torque correction map for every accelerator opening degree shown about the view of throttle opening correction in the throttle control. It is a characteristic view which shows the capacity | capacitance coefficient of a torque converter. It is a characteristic view which shows the torque ratio of a torque converter. FIG. 7 is a characteristic diagram showing an integration result of the capacity coefficient and the torque ratio shown in FIGS. 5 and 6. FIG. 8 is a characteristic diagram showing the outlet torque of the torque converter having the various characteristics shown in FIGS. 5, 6 and 7. It is a characteristic view which shows the relationship between the accelerator opening in the Example, and the peak value of a vehicle longitudinal acceleration. It is an algorithm for calculating the target torque converter outlet torque necessary for the throttle control of the same embodiment. FIG. 8 is a characteristic diagram showing an inlet torque of a torque converter having various characteristics shown in FIGS. 5, 6 and 7. In the same Example, it is a characteristic view which shows the relationship between a torque converter speed ratio required in order to implement | achieve a target engine torque, and an engine speed. The operation | movement time chart which shows the throttle opening performed by the throttle control of the Example is expanded and shown. In another Example, it is a characteristic view for calculating | requiring the throttle opening correction for throttle control before Gp. It is an operation | movement time chart which expands and shows the acceleration change etc. which are obtained as an effect of the throttle control of the Example. It is a characteristic view which shows the efficiency of a torque converter. In the same Example, it is an operation | movement time chart which shows the means for detecting the time of the peak value Gp of acceleration appearing. It is an algorithm which shows the other Example which detects the time of the peak value Gp of acceleration appearing. It is explanatory drawing which shows the throttle control in the Example in relation to a vehicle speed. In the characteristic diagrams showing the outlet torque of the torque converter having various characteristics shown in FIGS. 5, 6 and 7, the throttle opening is changed to the normal throttle opening when the control according to this embodiment is performed and after the throttle control before Gp is executed. It is explanatory drawing shown in comparison with the case where it does not change to.

Explanation of symbols

1 Engine 2 Transaxle 3 Accelerator pedal 4 Throttle valve 5 Throttle actuator 6 Engine controller 7 Throttle opening sensor 8 Engine speed sensor
15 Transmission controller
16 Transmission input speed sensor
17 Transmission output speed sensor

Claims (6)

An engine whose output is electronically controlled according to the driver's accelerator operation and an automatic transmission are drivingly coupled via a torque converter, which converts the engine speed and engine torque output from the engine. In the vehicle power train that inputs the input rotation speed to the automatic transmission,
A power train engine control device configured to calculate a speed ratio, which is a ratio between the engine speed and the input speed, and to control the output based on the speed ratio and the engine speed. . The engine control device according to claim 1 electronically controls a throttle opening of the engine having a throttle valve,
Means for determining a target acceleration of the vehicle based on an accelerator opening of an accelerator operator operated by a driver; means for calculating a target torque converter outlet torque output from the torque converter to the automatic transmission side based on the target acceleration; A means for determining the relationship between the speed ratio and the engine speed from the calculated target torque converter outlet torque, and a means for calculating the target throttle opening from the relationship between the determined speed ratio and the target engine speed,
An engine control device for a power train, wherein the throttle opening is electronically controlled so as to be the calculated target throttle opening. The engine control apparatus according to claim 2, wherein
A maximum acceleration point detection means is provided for detecting a point in time when the longitudinal acceleration peaks when the vehicle starts, and before that point, the target throttle opening is set to be smaller than the normal setting corresponding to the accelerator opening. After the time point, the engine control device for the power train is configured to return the target throttle opening set to a small value to a normal setting corresponding to the accelerator opening. The engine control apparatus according to claim 3, wherein
The maximum acceleration time point detection means obtains a rotation difference between the engine rotation speed and the input rotation speed, and detects a time point at which acceleration in the front-rear direction reaches a peak based on a change in time of the rotation difference. Powertrain engine control device. The engine control apparatus according to claim 3, wherein
The maximum acceleration time point detection means calculates a torque converter outlet torque based on the speed ratio and the engine speed, and detects a time point when the longitudinal acceleration reaches a peak at the start based on the time change of the calculated torque converter outlet torque. An engine control device for a power train. In the engine control device according to any one of claims 3 to 5,
An engine control device for a power train, wherein the throttle opening that has been set to a small value is returned to a normal setting based on the following equation after the time point when the longitudinal acceleration peaks after starting.
TVO = TVO ₁ + (TVO ₂ −TVO ₁ ) ・ (VSP−VSP ₁ ) / (VSP ₂ −VSP ₁ )
TVO ₂ is the normal throttle opening,
TVO ₁ refers to the throttle opening set to a small value,
VSP ₁ is the vehicle speed when the longitudinal acceleration becomes maximum,
VSP ₂ is the vehicle speed when the throttle opening converges to the normal setting,
VSP is the current vehicle speed
TVO refers to the throttle opening to be controlled.

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