JP2005105835A - Output torque controller of engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an output torque controller of an engine capable of preventing the engine rotational speed from reducing from just before the stopping till the stopping at the time of decelerating, in a vehicle equipped with a change gear with a torque converter. <P>SOLUTION: At the time of decelerating of the vehicle, when the rotational speed of a turbine shaft 9 (turbine rotational speed) is lower than the rotational speed of the crankshaft 1a (engine rotational speed), torque whose direction is opposed to the rotational direction acts on the crankshaft 1a by the rotational transmission between the crankshaft 1a and the turbine shaft 9 via fluid of the torque converter 2. The torque becomes the maximum from just before the stopping till the stopping of the vehicle, and this causes the reduction in the engine rotational speed below the idle rotational speed. In the predetermined time from just before the stopping of the vehicle, however, the output torque of the engine 1 is increased with the output torque increasing control so that the engine rotational speed can be prevented from reducing. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an engine output torque control device.

  In a vehicle such as an automobile equipped with a transmission with a torque converter, the engine is connected to the transmission through the torque converter, and rotation transmission between the engine side and the wheel side is performed through the torque converter and the transmission. (See Patent Document 1).

  A torque converter in such a vehicle includes a pump impeller connected to a crankshaft that is an output shaft of an engine, and a turbine impeller connected to a turbine shaft connected to a transmission, and a fluid existing between the impellers. The rotation transmission between the engine side and the transmission side is performed via With this torque converter, the rotational speed of the turbine shaft (turbine rotational speed) connected to the wheel side (transmission side) during acceleration or deceleration of the vehicle and the rotational speed of the crankshaft (engine rotational speed) that is the rotational speed of the engine side. ) Can also be transmitted between the transmission side and the engine side.

  For example, when the vehicle is decelerated, both the turbine rotation speed and the engine rotation speed are reduced, but at this time, a difference occurs in the rotation speed between the crankshaft and the turbine shaft according to the output state of the engine, the deceleration state of the vehicle, and the like. If the turbine rotation speed is lower than the engine rotation speed, the rotation of the turbine shaft is delayed with respect to the rotation of the crankshaft, but the crankshaft is rotated via the fluid between the turbine impeller and the pump impeller. Rotational transmission is performed between the shaft and the turbine shaft.

However, when such rotation transmission is performed, rotational torque through the fluid acts on both the crankshaft and the turbine shaft, which affects the engine rotational speed and the turbine rotational speed. That is, the rotation of the crankshaft acts as a torque in the same direction as the rotation direction on the turbine shaft via the fluid, and the decrease in turbine rotation speed is delayed by this torque. On the other hand, the rotation of the turbine shaft acts as a torque in the direction opposite to the direction of rotation of the crankshaft via the fluid, and this torque causes a decrease in engine rotation speed.
JP-A-6-173729

  By the way, when the vehicle is decelerating and the turbine rotation speed is lower than the engine rotation speed, the torque in the direction opposite to the rotation direction acting on the crankshaft increases as the turbine rotation speed decreases more rapidly. Become. Here, when the vehicle is decelerated, from immediately before the vehicle is stopped until it stops, the turbine rotational speed rapidly decreases from a predetermined value to “0”. The decrease is abrupt, and the torque acting on the crankshaft in the direction opposite to the rotation direction is also large. Further, immediately before the vehicle stops, the engine speed decreases to near the idle speed. In such a state, if the torque acting on the crankshaft in the direction opposite to the rotation direction increases, the engine rotation speed suddenly drops below the idle rotation speed, causing vibration associated with low engine rotation speed. In the worst case, engine stall may occur.

  In particular, when a belt-type continuously variable transmission (CVT) is adopted as the transmission, the above-described drop in engine rotation speed from stop to stop of the vehicle becomes significant. The CVT receives oil supply from an oil pump driven by an engine, and thereby drives gear shifting, etc., but immediately before stopping the vehicle, the gear ratio is increased in preparation for the next start and acceleration. Driven accordingly. In order to obtain the oil pressure necessary to drive this CVT, the amount of work of the oil pump increases, and the increased amount of work becomes the oil pump driving load of the engine, increasing the torque in the direction opposite to the rotational direction acting on the crankshaft. Cause it. Thus, by adopting CVT, the torque in the reverse direction is further increased immediately before the vehicle is stopped, so that the engine speed drops significantly as described above.

  The present invention has been made in view of such circumstances, and an object of the present invention is to suppress a drop in engine rotation speed from just before stopping to when stopping in a vehicle equipped with a transmission with a torque converter. Another object of the present invention is to provide an engine output torque control device capable of performing

In the following, means for achieving the above object and its effects are described.
In order to achieve the above object, according to the first aspect of the present invention, in an engine output torque control device connected to a transmission of a vehicle via a torque converter, a predetermined period from when the vehicle is decelerated and immediately before the vehicle is stopped. And a control means for increasing the output torque of the engine.

  When the vehicle is decelerating, if the speed on the transmission side is lower than the speed on the engine side, the fluid between the pump impeller and the turbine impeller of the torque converter is connected between the transmission side and the engine side. When transmission of rotation is performed, torque through the fluid in the direction opposite to the rotation direction acts on the engine side. This torque becomes larger as the reduction in the rotational speed on the transmission side becomes steep, so that the torque increases when the rotational speed on the transmission side suddenly decreases to “0” immediately before the stop of the vehicle. There is a risk of a drop in rotational speed. However, according to the above configuration, since the output torque of the engine is increased from immediately before the vehicle is stopped until the vehicle is stopped, and the rotational speed on the engine side is increased, the torque generated in the direction opposite to the rotational direction acting on the engine side is increased. A drop in engine speed can be suppressed.

  According to a second aspect of the present invention, in the first aspect of the present invention, the control means controls the output torque on the condition that the rotational speed of the turbine wheel of the torque converter is lower than the engine rotational speed by a predetermined amount or more. It was supposed to increase.

  When the vehicle is decelerating, if the transmission-side rotation speed, that is, the turbine impeller rotation speed is higher than the engine-side rotation speed (engine rotation speed), increasing the engine output torque immediately before stopping the vehicle will cause the engine rotation. The speed increases and becomes larger than the rotational speed of the turbine impeller. In this case, the engine rotational speed changes from small to large with respect to the rotational speed of the turbine impeller, and the torque acting on the engine side by the rotational transmission between the transmission side and the engine side at that time is the rotational direction of the engine. The direction is switched from the opposite direction to the same direction, and a shock occurs. However, according to the above configuration, the engine output torque is increased on the condition that the rotational speed of the turbine wheel of the torque converter is lower than the engine rotational speed by a predetermined amount or more, thereby increasing the engine rotational speed. In this case, the direction in which the torque acts does not change. Therefore, it is possible to prevent a shock from being generated with the switching of the direction in which the torque acts.

  According to a third aspect of the present invention, in the first or second aspect of the invention, the control means changes an output torque increase amount when the output torque is increased according to an operating state of an air conditioner of the vehicle. To do.

  The driving load of the air conditioner in the engine is different between when the air conditioner is driven and when it is not driven, and the magnitude of torque in the direction opposite to the rotational direction acting on the engine side due to the driving load is also different. . As a result, the manner in which the engine rotational speed decreases immediately before and after the vehicle stops varies depending on the operating state of the air conditioner. According to the above configuration, when increasing the output torque of the engine from just before the vehicle stops until the vehicle stops, the output torque increase amount is changed according to the operating condition of the air conditioner and changes according to the operating condition of the air conditioner. The engine rotation speed is increased in correspondence with the engine rotation speed decrease mode. For this reason, it is possible to appropriately suppress a drop in the engine rotation speed from immediately before the vehicle is stopped to when the vehicle is stopped, according to the operating condition of the air conditioner.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, after the control means increases the output torque, the rate of decrease in the engine rotation speed becomes less than a predetermined level. Or when the engine rotation speed starts to increase, the increase in the output torque is terminated.

  The output torque of the engine increases from just before the vehicle stops until it stops. When the rate of decrease in the engine rotation speed falls below a predetermined level or when the engine rotation speed starts to increase, the engine output torque increases. It can be determined that the decrease in engine rotation speed is suppressed by the increase in output torque. According to the above configuration, since the increase in the engine output torque is terminated when the situation is changed, the increase is not continued unnecessarily.

  According to a fifth aspect of the present invention, in the invention according to any one of the first to third aspects, the rotation speed of the turbine wheel of the torque converter is “0” after the control means increases the output torque. , The increase in the output torque is terminated.

  When the rotational speed of the turbine wheel of the torque converter approaches “0”, the torque in the reverse direction acting on the engine side as the rotation is transmitted between the transmission side and the engine side approaches “0”. In other words, it can be determined that the engine rotational speed does not drop. According to the above configuration, since the increase in the engine output torque is terminated when the situation is changed, the increase is not continued unnecessarily.

  According to a sixth aspect of the invention, in the invention according to any of the first to fifth aspects, the control means increases the output torque by adjusting an intake air amount of the engine.

  In the engine, as the intake air amount increases, the fuel injection amount increases and the output torque increases. For this reason, it is possible to appropriately realize an increase in the engine output torque from immediately before the vehicle stops until the vehicle stops by adjusting the intake air amount of the engine.

  The invention according to claim 7 is the belt-type continuously variable transmission according to any one of claims 1 to 6, wherein the transmission is hydraulically driven based on oil discharge from an oil pump driven by an engine. In this case, the vehicle is driven to increase the reduction ratio when the vehicle is decelerated.

  The belt-type continuously variable transmission is supplied with oil from an oil pump driven by an engine, and thereby performs driving such as gear shifting (hydraulic driving). Immediately before the vehicle stops, the next start and acceleration are performed. In order to prepare for this, it is driven to increase the gear ratio. In order to obtain the hydraulic pressure necessary to drive such a belt-type continuously variable transmission, the amount of work of the oil pump increases, and the increased amount of work becomes the load for driving the oil pump of the engine. This increases the torque in the direction opposite to the rotational direction in which it acts. Therefore, when a belt-type continuously variable transmission is used as a transmission, the reverse torque increases further immediately before the vehicle stops and the engine rotational speed drops significantly. Can be suppressed.

Hereinafter, an embodiment in which the present invention is applied to an automobile engine will be described with reference to FIGS.
FIG. 1 is a schematic diagram showing a drive system of an automobile provided with a transmission with a torque converter. The rotation of the engine 1 mounted on the automobile as a prime mover is transmitted to the wheels of the automobile via the torque converter 2, the forward / reverse switching device 3, the belt type continuously variable transmission (CVT) 4, and the like. The torque converter 2, the forward / reverse switching device 3, the belt-type continuously variable transmission 4, and the like constitute an automobile transmission.

  In the engine 1, the opening degree of the throttle valve 6 (throttle opening degree) provided in the intake passage 5 is such that the depression amount (accelerator depression amount) of the accelerator pedal 7 that is operated by the driver of the automobile. Control is performed in response to an output request to the engine 1. The intake air amount of the engine 1 is adjusted by the throttle opening control, and fuel injection corresponding to the intake air amount is performed through the fuel injection valve 13. Then, the amount of the air-fuel mixture consisting of fuel and air filled in the combustion chamber of the engine 1 is adjusted, whereby the output torque of the engine 1 is changed. Accordingly, the output torque control of the engine 1 is realized by adjusting the intake air amount through the opening degree control of the throttle valve 6. The engine output is used not only for driving the automobile but also for driving an air conditioner 22 for air conditioning the interior of the automobile.

  The torque converter 2 includes a pump impeller 8 connected to a crankshaft 1 a that is an output shaft of the engine 1, a turbine blade connected to a forward / reverse switching device 3 and a belt-type continuously variable transmission 4 via a turbine shaft 9. A vehicle 10 is provided, and rotation transmission between the pump impeller 8 and the turbine impeller 10 is performed via a fluid. An oil pump 11 is connected to the pump impeller 8. The oil pump 11 is driven based on the rotation of the pump impeller 8 (engine rotation), and discharges oil for hydraulically driving the belt-type continuously variable transmission 4 and operating the forward / reverse switching device 3. The oil discharge pressure of the oil pump 11 increases as the engine speed increases.

  The torque converter 2 is provided with a lock-up clutch 12 that directly connects and disconnects the crankshaft 1a and the turbine shaft 9. The operation state of the lockup clutch 12 is changed between a “directly connected state” in which the crankshaft 1 a and the turbine shaft 9 are directly connected and a “released state” in which the directly connected state is released. Further, the lock-up clutch 12 is in an intermediate state between the “directly connected state” and the “released state”, that is, allows a relative rotation between the crankshaft 1a and the turbine shaft 9 to some extent, and is partially engaged in a “slip state”. Can also be taken.

  The forward / reverse switching device 3 switches the direction of input rotation from the turbine shaft 9 with respect to the input shaft 4a of the belt-type continuously variable transmission 4 between the forward rotation direction and the reverse rotation direction, or the turbine to the input shaft 4a. The rotation input from the shaft 9 is cut off. The operation of the forward / reverse switching device 3 is performed based on the oil discharge pressure of the oil pump 11 based on the operation of the shift lever 28 by the driver of the automobile. The shift lever 28 includes a “P” position for parking, an “R” position for reverse travel, an “N” position for blocking rotation transmission from the engine side to the wheel side, and a “D” position for forward travel. And “L” position.

  When the shift lever 28 is operated to the “D” position or the “L” position, the input shaft 4 a of the belt type continuously variable transmission 4 is rotated in the forward rotation direction by the operation of the forward / reverse switching device 3. When the shift lever 28 is operated to the “R” position, the forward / reverse switching device 3 rotates the input shaft 4 a of the belt type continuously variable transmission 4 in the reverse rotation direction. Further, when the shift lever 28 is operated to the “P” position or the “N” position, the input of the rotation from the turbine shaft 9 to the input shaft 4a is cut off by the operation of the forward / reverse switching device 3, and the input shaft 4a No longer rotates.

  The belt type continuously variable transmission 4 includes a primary pulley 18 provided on the input shaft 4a, a secondary pulley 19 provided on the output shaft 4b, and a belt 20 wound around the pulleys 18 and 19. . The primary pulley 18 is displaced with a predetermined moving force in the axial direction of the input shaft 4a in order to change the speed ratio of the belt-type continuously variable transmission 4 by changing the distance from the rotation center to the belt 20. The adjustment of the gear ratio by the displacement of the primary pulley 18 is realized by adjusting the hydraulic pressure acting on the primary pulley 18 through the hydraulic control circuit 21. The secondary pulley 19 is displaced in the axial direction of the output shaft 4b so as to adjust the belt clamping pressure so that the belt 20 does not slip with respect to the pulleys 18 and 19. The adjustment of the belt clamping pressure due to the displacement of the secondary pulley 19 is realized by adjusting the hydraulic pressure acting on the secondary pulley 19 through the hydraulic control circuit 21.

  The hydraulic control circuit 21 adjusts the oil discharge pressure of the oil pump 11 to a line pressure that is a hydraulic pressure used to drive the belt-type continuously variable transmission 4 and the forward / reverse switching device 3, and based on the line pressure. Thus, the hydraulic pressure acting on the primary pulley 18 and the secondary pulley 19 is regulated. As described above, the gear ratio of the belt-type continuously variable transmission 4 is changed by adjusting the hydraulic pressure acting on the primary pulley 18. As an example of such a gear ratio change, the vehicle is being decelerated and stopped. The last change can be given. That is, immediately after the vehicle is decelerating and immediately before it stops, it is necessary to increase the gear ratio in preparation for the next start and acceleration of the vehicle, so that the hydraulic pressure acting on the primary pulley 18 to increase the gear ratio is increased. Is regulated.

Next, the electrical configuration of the output torque control device for the engine 1 in this embodiment will be described.
The output torque control device includes an engine control computer 25 that controls the operation of the engine 1. The engine control computer 25 is connected to a transmission control computer 26 that controls the forward / reverse switching device 3 and also controls the hydraulic control circuit 21 to hydraulically drive the belt-type continuously variable transmission 4. .

  The engine control computer 25 receives a detection signal from an accelerator position sensor 27 that detects the amount of depression of the accelerator pedal 7 (accelerator depression amount). The engine control computer 25 adjusts the intake air amount of the engine 1 by controlling the opening of the throttle valve 6 based on the accelerator depression amount and the like, and a fuel injection valve so that an amount of fuel corresponding to the intake air amount is injected. 13 is driven to control the fuel injection amount.

  The engine control computer 25 includes a crank position sensor 14 that outputs a signal corresponding to the rotation of the crankshaft 1a, a water temperature sensor 15 that detects the cooling water temperature of the engine 1, and a brake pedal 16 that is depressed by the driver. Detection signals from various sensors such as a brake switch 17 for detecting the presence or absence of depression are input. Further, a signal corresponding to the driving state (ON / OFF) of the air conditioner is also input to the engine control computer 25.

  On the other hand, the transmission control computer 26 detects position information corresponding to the operation position of the shift lever 28, a detection signal from the vehicle speed sensor 29 that detects the vehicle speed of the automobile, and the rotational speed of the turbine shaft 9 (turbine impeller 10). The detection signal from the turbine rotation speed sensor 30 is input. The transmission control computer 26 shifts the belt-type continuously variable transmission 4 and drives the forward / reverse switching device 3 through the control of the hydraulic control circuit 21.

  By the way, in an automobile equipped with a transmission with a torque converter, when the lock-up clutch 12 is in a released state, rotation between the crankshaft 1a of the engine 1 and the turbine shaft 9 connected to the wheel side (transmission 4 side). Transmission takes place through the fluid present between the pump impeller 8 and the turbine impeller 10 of the torque converter 2. Even if there is a difference between the rotational speed of the crankshaft 1a (engine rotational speed) and the rotational speed of the turbine shaft 9 (turbine rotational speed) due to the rotation transmission through the fluid of the torque converter 2, the crankshaft 1a Rotational transmission between the turbine shaft 9 is possible.

  Here, when both the turbine rotational speed and the engine rotational speed decrease during deceleration of the automobile, the rotational transmission between the crankshaft 1a and the turbine shaft 9 when the turbine rotational speed is lower than the engine rotational speed is shown in FIG. This will be discussed with reference to the time chart.

  FIG. 3A shows the transition of the turbine rotational speed and the engine rotational speed under such a situation. FIG. 3 (b) shows a decrease in the vehicle speed when the automobile is decelerated. When the vehicle decelerates, the throttle opening is minimized by setting the accelerator depression amount to “0”. Therefore, the intake air amount of the engine 1 decreases until the vehicle stops, and the engine rotation speed becomes the idle rotation speed. Will begin to decline. In addition, the turbine rotation speed changes in accordance with the amount of depression of the brake pedal 16 by the driver, but reaches “0” when the automobile is stopped.

  As can be seen from FIG. 3A, when the turbine rotation speed is lower than the engine rotation speed, the rotation of the turbine shaft 9 is delayed with respect to the rotation of the crankshaft 1a. At this time, rotation transmission is performed between the crankshaft 1 a and the turbine shaft 9 via the fluid existing between the pump impeller 8 and the turbine impeller 10. However, when such rotation transmission is performed, torque through the fluid acts on both the crankshaft 1a and the turbine shaft 9 and affects the engine rotation speed and the turbine rotation speed.

  That is, the rotation of the crankshaft 1a acts as a torque in the same direction as the rotation direction on the turbine shaft 9 via the fluid, while the rotation of the turbine shaft 9 affects the crankshaft 1a via the fluid. It acts as a torque in the direction opposite to the rotation direction. For this reason, when rotation transmission is performed as described above, the decrease in the turbine rotation speed is delayed and the decrease in the engine rotation speed proceeds. By the way, the torque in the direction opposite to the rotational direction acting on the crankshaft 1a increases as the turbine rotational speed decreases more rapidly (large deceleration). For this reason, the mode of decrease in the engine rotation speed in the above case becomes steeper as the deceleration of the turbine rotation speed increases.

  The decrease in the turbine rotation speed when the automobile is decelerating is the steepest from immediately before the automobile stops (timing T1) to when the brake pedal 16 is depressed. This is because the turbine rotational speed rapidly decreases from a predetermined value to “0” immediately before the vehicle stops (timing T1) until the vehicle stops. Therefore, the reverse torque that acts on the crankshaft 1a during the deceleration of the automobile suddenly increases in the period from immediately before stopping the automobile to the stop compared to the period before the stop. For this reason, the engine rotational speed drops significantly as shown by the broken line in FIG.

  In addition, immediately before the automobile stops, the engine rotation speed decreases to near the idle rotation speed. In such a state, when the torque in the direction opposite to the rotational direction acting on the crankshaft 1a is increased, a sudden drop of the engine rotational speed to less than the idle rotational speed occurs, causing vibration associated with low engine speed, In the worst case, engine stall may occur.

  In particular, in an automobile equipped with the belt type continuously variable transmission 4, the engine speed drops significantly from just before the stop to the stop at the time of deceleration. This is because in a vehicle equipped with a belt-type continuously variable transmission 4, the belt-type continuously variable transmission 4 is hydraulically driven to increase the gear ratio in preparation for the next start and acceleration immediately before stopping after deceleration. It is. That is, in order to obtain this hydraulic pressure, the work amount of the oil pump 11 is increased, and the increased work amount becomes an oil pump driving load of the engine 1, and the torque in the direction opposite to the rotation direction acting on the crankshaft 1a is further increased. As a result, the drop in the engine rotation speed becomes significant.

  In view of such circumstances, in the present embodiment, output torque increase control for increasing the output torque of the engine 1 is executed for a predetermined period from when the vehicle is decelerated and immediately before the vehicle is stopped. That is, the output torque of the engine 1 is increased by correcting the increase of the intake air amount of the engine 1 by the correction amount H shown in FIG. 3C and increasing the fuel injection amount. By performing such output torque increase control, the above-described drop in engine rotation speed is suppressed as shown by the solid line in FIG. 3A, and vibration and stall of the engine 1 are suppressed.

  Next, the execution procedure of the output torque increase control will be described with reference to the flowchart of FIG. 2 showing the output torque increase routine. This output torque increase routine is executed through the engine control computer 25 by, for example, a time interruption every predetermined time.

  In the output torque increase routine, it is determined whether or not the correction amount H is 0, that is, whether or not the output torque increase control has already been executed (S101). If the determination is affirmative and it is determined that the output torque increase control has not been executed, the processing from step S102 onward is executed. In the output torque increase routine, steps S102 to S106 are correction amount calculation processing for calculating the correction amount H as a value larger than “0” at the start of the output torque increase control, and steps S107 and S108 are output torque increase control. Is a correction amount attenuation process for attenuating the correction amount H toward “0” at the end of.

  Step S109 is a process for increasing the intake air amount by the correction amount H. That is, the throttle valve 6 is controlled to be opened by an amount corresponding to the correction amount H, and the intake air amount is increased by the correction amount H, whereby the output of the engine 1 for suppressing the above-described drop in engine rotation speed. Torque can be increased. Therefore, the output torque increase control is not performed while the correction amount H is “0”, and is performed when the correction amount H is a value larger than “0”.

Hereinafter, details of each of the correction amount calculation processing in steps S102 to S106 and the correction amount attenuation processing in steps S107 and S108 will be individually described.
[Correction amount calculation processing]
In a series of processes of steps S102 to S106 for calculating the correction amount H as a value larger than “0” at the start of output torque control, it is determined in step S102 whether or not a precondition for calculating the correction amount H is satisfied. In step S103, it is determined whether or not a condition for calculating the correction amount H is satisfied. Note that the calculation preconditions in step S102 include the following conditions [1] to [5], and the calculation conditions in step S103 include, for example, the following conditions [6] to [8].

[1] The cooling water temperature of the engine 1 is a predetermined value (for example, 80 ° C.) or more.
[2] The vehicle is decelerating with the lock-up clutch 12 being released.
[3] An idle state (accelerator depression amount = “0”, throttle opening is minimum, etc.).

[4] The brake pedal 16 is being depressed.
[5] The vehicle speed is a predetermined value (for example, 8 km / h) or less.
[6] The turbine rotation speed is lower than the engine rotation speed by a predetermined amount (for example, 20 rpm) or more.

[7] The rate of decrease in engine speed is large.
[8] Large reduction rate of turbine rotation speed.
Then, based on the fact that all the conditions [1] to [5] are satisfied, it is determined that the calculation precondition is satisfied, an affirmative determination is made in step S102, and the process proceeds to step S103. Furthermore, in step S103, based on the fact that all the conditions [6] to [8] are satisfied, it is determined that the calculation condition is satisfied, and an affirmative determination is made. After an affirmative determination is made in step S103, the correction amount H is calculated as a value larger than “0” (S104 to S106), and output torque increase control is started.

  The above conditions [2] to [5] relating to the calculation precondition are for determining whether or not the vehicle to be decelerated is just before stopping. Therefore, when the calculation precondition is satisfied, it can be determined that the vehicle is decelerating and immediately before stopping (timing T1 in FIG. 3). For this reason, the output torque increase control is started when the automobile is decelerated and immediately before stopping.

  Further, the condition [6] relating to the calculation condition is for determining whether or not the engine 1 is in a state where no shock is caused by the execution of the output torque increase control. If this condition is not included in the calculation condition, the output torque control may be executed in a situation where the turbine rotation speed is higher than the engine rotation speed, for example. FIG. 4 shows how the engine rotation speed and the turbine rotation speed change when the output torque increase control is executed under such a situation. In a state where the turbine rotational speed is higher than the engine rotational speed as shown in FIG. 4A, the correction amount H becomes a value larger than “0” as shown in FIG. When the control is performed (timing T3), the engine speed increases and exceeds the turbine speed. In this case, the engine rotational speed changes from small to large with respect to the turbine rotational speed (timing T4), and at that time, due to the rotational transmission between the crankshaft 1a and the turbine shaft 9 via the fluid of the torque converter 2 The torque acting on the crankshaft 1a is switched from the direction opposite to the rotation direction of the shaft 1a to the same direction, and a shock is generated. However, the calculation condition includes the condition [6]. When the calculation condition is satisfied, it can be determined that the above-described shock is not caused by the execution of the output torque increase control. For this reason, the output torque increase control is started in a situation where the shock is not generated.

  When an affirmative determination is made in steps S102 and S103, the process proceeds to step S104. In step S104, it is determined whether or not the air conditioner 22 is in a non-driven state (off). If the determination is affirmative, a value equivalent to 500 rpm is set as the correction amount H in terms of the engine rotation speed (S105). If the determination is negative, a value equivalent to 800 rpm is set as the correction amount H in terms of the engine rotation speed ( S106). For this reason, in the output torque control when the air conditioner 22 is on, compared to the output torque control when the air conditioner 22 is off, the throttle valve 6 is opened corresponding to the correction amount H. And the output torque increase amount of the output torque control is increased accordingly.

  When the air conditioner 22 is turned on and when it is turned off, the driving load of the air conditioner 22 in the engine 1 is different, and the rotational direction acting on the crankshaft 1a due to the driving load is different from the rotational direction. The reverse torque is also different. As a result, the decrease in engine rotation speed immediately before and after the vehicle stops is also greater when the air conditioner 22 is on than when it is off. In consideration of this, as described above, the correction amount H at the time of output torque control is changed according to the driving state (ON / OFF) of the air conditioner 22, so that the decrease in the engine speed is controlled by the air conditioner 22. Can be appropriately suppressed according to the on / off state.

[Correction amount attenuation processing]
In the processing of steps S107 and S108 (FIG. 2) for attenuating the correction amount H toward “0” when ending the output torque increase control, it is determined in step S107 whether or not an attenuation condition is satisfied. . Examples of the attenuation condition include the following conditions [9] to [11].

[9] The engine rotational speed has started to increase from a decrease.
[10] The turbine rotation speed has reached “0”.
[11] A predetermined time t has elapsed since the start of the output torque increase control.

  Then, based on the fact that any one of the conditions [9] to [11] is satisfied, it is determined that the attenuation condition is satisfied, an affirmative determination is made in step S107, and the process proceeds to step S108. In step S108, the correction amount H set to a value larger than “0” for the output torque increase control is gradually decreased toward “0” as shown after timing T2 in FIG. Is done. Then, when the correction amount H reaches “0”, the output torque increase control ends.

  The condition [9] relating to the damping condition is for determining whether or not a drop in the engine rotation speed immediately before and after the vehicle is stopped is suppressed by the output torque increase control. Therefore, when the condition [9] is satisfied, it can be determined that the decrease in the engine speed has been suppressed by the output torque increase control, and the output torque increase control is terminated based on this determination.

  The condition [10] relating to the damping condition is for determining whether or not the turbine rotational speed has approached “0” so that it can be determined that the automobile has stopped. When the turbine rotational speed approaches “0” so that it can be determined that the automobile has stopped, a torque in the direction opposite to the rotational direction acting on the crankshaft 1 a is transmitted along with the rotational transmission between the crankshaft 1 a and the turbine shaft 9. This means that the engine speed is almost “0”, and it can be determined that the engine speed does not drop. Accordingly, when the condition [10] is satisfied, it is determined that the engine speed does not drop, and the output torque increase control is terminated based on this determination.

  The condition [11] relating to the damping condition is for guarding the upper limit of the execution time of the output torque increase control. That is, after the start of the output torque increase control, if the output torque increase control is not terminated due to the satisfaction of the conditions [9] and [10], the condition [11] is satisfied to terminate the output torque increase control at an appropriate timing. Thus, the output torque increase control ends.

According to the embodiment described in detail above, the following effects can be obtained.
(1) When the automobile is decelerated, if the turbine rotational speed is lower than the engine rotational speed, the rotational transmission between the crankshaft 1a and the turbine shaft 9 through the fluid of the torque converter 2 causes the crankshaft 1a to The torque in the direction opposite to the rotational direction acts. This torque becomes the largest from immediately before the automobile stops until it stops, and causes the engine speed to drop below the idle speed. However, since the output torque of the engine 1 is increased by the output torque increase control for a predetermined time immediately before the stop of the vehicle and the decrease in the engine rotation speed is suppressed, the vibration or stall of the engine 1 due to the decrease is suppressed. Can be suppressed.

  (2) The output torque control is a situation in which the engine 1 is not shocked with an increase in the engine speed when the output torque is increased by the control, such that the turbine speed is lower than the engine speed by a predetermined amount or more. Will be started on condition. For this reason, when the turbine rotation speed is higher than the engine rotation speed, the output torque is increased by the output torque increase control, and it is possible to prevent a shock from occurring due to the increase in the engine rotation speed.

  (3) The amount of increase in the output torque in the output torque control varies depending on the magnitude of the correction amount H. The magnitude of the correction amount H is larger when the air conditioner 22 is on than when it is off. Set to a value. The decrease in engine rotation speed immediately before and after the vehicle stops increases as the driving load of the air conditioner 22 in the engine 1 increases. However, by setting the correction amount H as described above, the air conditioner 22 It is possible to appropriately suppress a drop in engine rotation speed according to on / off.

  (4) After the output torque control is started, when the change in the engine rotation speed is changed from the decrease to the increase, it can be determined that the decrease in the engine rotation speed is suppressed by the increase in the output torque in the control. Then, based on this determination, the output torque control ends. Therefore, the output torque control is not continued unnecessarily.

  (5) Further, after the output torque control is started, when it can be determined that the turbine rotation speed reaches “0” and the automobile has stopped, the engine rotation speed does not drop. Control is terminated. Therefore, the output torque control is not continued unnecessarily.

  (6) In the engine 1, as the intake air amount increases, the fuel injection amount increases, and the output torque increases. For this reason, in the output torque increase control, the throttle valve 6 is controlled to the open side by an amount corresponding to the correction amount H, and the intake air amount of the engine 1 is increased, so that the output for suppressing the drop in the engine rotation speed is controlled. An increase in torque can be appropriately realized.

  (7) In an automobile equipped with the belt type continuously variable transmission 4, the above-mentioned drop in the engine speed from the stop to the stop becomes remarkable. This is an increase in the output torque of the engine 1 by the output torque increase control. Can be suppressed.

In addition, the said embodiment can also be changed as follows, for example.
-Although the belt-type continuously variable transmission was illustrated as a transmission of a motor vehicle, it may change to this and may employ | adopt the automatic transmission provided with the planetary gear mechanism.

  The condition [9] relating to the damping condition may be changed to a condition that “the rate of decrease in engine rotation speed is less than a predetermined level”. Even in this case, when the condition is satisfied, it can be determined that the decrease in the engine rotation speed is suppressed by the output torque increase control.

  The condition [10] relating to the damping condition may be changed to a condition that “the turbine rotation speed has reached a predetermined value slightly larger than“ 0 ””. Even in this case, it is possible to determine that the turbine rotational speed has approached “0” when the condition is satisfied.

  The condition [10] may be changed to the condition that “the vehicle speed has reached“ 0 ”” or “the vehicle speed has reached a predetermined value slightly higher than“ 0 ””. Such a change is possible because the vehicle speed changes corresponding to the turbine rotation speed.

Although the correction amount H used for the output torque increase control is variably set according to whether the air conditioner 22 is turned on or off, such variable setting is not necessarily performed.
-Regarding the condition [6] concerning the calculation condition, the predetermined amount (20 rpm in the above embodiment) may be appropriately changed to a value larger or smaller than 20 rpm. When the predetermined amount is changed to a value smaller than 20 rpm, for example, the predetermined amount can be set to 0 rpm.

Schematic which shows the drive system of the motor vehicle carrying the engine to which the output torque control apparatus of this embodiment is applied. The flowchart which shows the execution procedure of output torque increase control. (A)-(c) is a time chart which shows transition of the engine rotational speed and turbine rotational speed at the time of deceleration of a motor vehicle, vehicle speed, and the correction amount H. FIG. (A) And (b) is a time chart which shows transition of the engine rotational speed and turbine rotational speed at the time of deceleration of a motor vehicle, and the correction amount H. FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Engine, 1a ... Crankshaft, 2 ... Torque converter, 3 ... Forward / reverse switching device, 4 ... Belt type continuously variable transmission, 4a ... Input shaft, 4b ... Output shaft, 5 ... Intake passage, 6 ... Throttle valve, DESCRIPTION OF SYMBOLS 7 ... Accelerator pedal, 8 ... Pump impeller, 9 ... Turbine shaft, 10 ... Turbine impeller, 11 ... Oil pump, 12 ... Lock-up clutch, 13 ... Fuel injection valve, 14 ... Crank position sensor, 15 ... Water temperature sensor, DESCRIPTION OF SYMBOLS 16 ... Brake pedal, 17 ... Brake switch, 18 ... Primary pulley, 19 ... Secondary pulley, 20 ... Belt, 21 ... Hydraulic control circuit, 22 ... Air conditioner, 25 ... Engine control computer (control means), 26 ... Transmission control Computer, 27 ... Accelerator position sensor, 28 ... Shift lever , 29 ... vehicle speed sensor, 30 ... turbine speed sensor.

Claims (7)

In an engine output torque control device connected to a vehicle transmission via a torque converter,
An engine output torque control device comprising control means for increasing the output torque of the engine for a predetermined period immediately before stopping when the vehicle is decelerated. The engine output torque control device according to claim 1, wherein the control means increases the output torque on condition that a rotational speed of a turbine impeller of the torque converter is lower than a predetermined amount with respect to an engine rotational speed. The engine output torque control device according to claim 1 or 2, wherein the control means changes an output torque increase amount when the output torque is increased in accordance with an operating state of an air conditioner of a vehicle. The control means ends the increase of the output torque when the decrease rate of the engine rotation speed becomes less than a predetermined level after the increase of the output torque or when the engine rotation speed starts to increase. Item 4. The engine output torque control device according to any one of Items 1 to 3. The control means ends the increase in the output torque when it is determined that the rotational speed of the turbine impeller of the torque converter has approached "0" after executing the increase in the output torque. The engine output torque control device according to any one of the above. The engine output torque control device according to any one of claims 1 to 5, wherein the control means increases the output torque by adjusting an intake air amount of the engine. The transmission is a belt-type continuously variable transmission that is hydraulically driven based on oil discharge from an oil pump driven by an engine, and is driven to increase a reduction ratio when the vehicle is decelerated. Item 7. The engine output torque control device according to any one of Items 1 to 6.

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