JP2009180361A - Vehicle power train control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve fuel economy without worsening an acceleration feeling at starting a vehicle. <P>SOLUTION: When required torque (torque required by a driver) corresponding to an accelerator opening is smaller than maximum torque generated by an engine 11 at starting the vehicle, the required torque is determined to be generated without using a torque converter 52 without largely amplifying engine torque, and a lock-up clutch 56 is controlled to be fastened (into a completely fastened state or a predetermined slipped state), thus improving the transmitting efficiency of an engine output to improve fuel economy without worsening the acceleration feeling at starting the vehicle. On the other hand, when the required torque is not smaller than the maximum torque at starting the vehicle, the required torque is determined to be generated by using only the torque converter 52 for amplifying the engine torque and the release control of the lock-up clutch is executed. Thus, the torque amplifying operation of the torque converter 52 is used for generating the required toque to improve the acceleration feeling at starting the vehicle. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a vehicle powertrain control device that transmits the power of an internal combustion engine to a wheel side via a torque converter with a lock-up clutch and a transmission mechanism.

  In vehicles equipped with a torque converter with a lock-up clutch, the slip amount of the lock-up clutch (rotational speed difference between the input shaft side and the output shaft side) is controlled according to the driving state of the vehicle for the purpose of improving fuel efficiency. There are some which improve the transmission efficiency of the output of the internal combustion engine by controlling the lock-up clutch to a completely engaged state or a predetermined slip state.

For example, Patent Document 1 (Japanese Patent Laid-Open No. 2005-3193) proposes a technique for controlling a lock-up clutch to a slip state from the start of the vehicle. This technology controls the lock-up clutch to a slip state so that a torque larger than the transmission torque capacity of the torque converter is not input from the internal combustion engine when the vehicle starts, and suppresses the increase in the rotational speed of the internal combustion engine. The fuel consumption is improved.
Japanese Patent Laying-Open No. 2005-3193 (second page, etc.)

  However, the torque converter generates a torque amplification effect by increasing the rotational speed difference between its input and output shafts, and has the purpose of improving the acceleration feeling at the start of the vehicle by the torque amplification effect, If the lockup clutch is controlled to the slip state or the fully engaged state only for the purpose of improving the fuel efficiency when starting the vehicle, the torque amplification function of the torque converter cannot be effectively used when starting the vehicle, and the driver There are cases where the requested acceleration torque cannot be realized, and there is a possibility that a feeling of rattling can be felt even if the acceleration feeling at the start of the vehicle deteriorates.

  The present invention has been made in view of such circumstances, and therefore, an object of the present invention is to control the powertrain of a vehicle that can improve fuel efficiency without deteriorating acceleration feeling when the vehicle starts. To provide an apparatus.

  In order to achieve the above object, an invention according to claim 1 is directed to a vehicle powertrain control device for transmitting power of an internal combustion engine to a wheel side via a torque converter with a lock-up clutch and a transmission mechanism. When the required torque set according to the accelerator opening at the time of start is smaller than the maximum torque that can be generated by the internal combustion engine, lock-up clutch control means that controls the lock-up clutch to the engagement side is executed by the lock-up clutch control means If you do.

  In this configuration, when the required torque (that is, the torque required by the driver) corresponding to the accelerator opening when the vehicle starts is smaller than the maximum torque that can be generated by the internal combustion engine, the torque of the internal combustion engine is reduced by the torque converter. It is determined that the required torque can be achieved without amplification, and the vehicle is started by executing lock-up clutch engagement side control for controlling the lock-up clutch to the engagement side (for example, a complete engagement state or a predetermined slip state). The fuel efficiency can be improved by increasing the power transmission efficiency of the internal combustion engine without sometimes deteriorating the acceleration feeling.

  On the other hand, if the required torque is greater than or equal to the maximum torque at the start of the vehicle, it is determined that the required torque cannot be achieved unless the torque of the internal combustion engine is amplified by the torque converter, and the lockup clutch engagement side control is not performed and the lock is performed. By controlling the up-clutch to the disengaged state, the required torque can be realized using the torque amplification action of the torque converter, and the acceleration feeling at the start of the vehicle can be improved.

  In this case, the lockup clutch engagement side control may be executed when the required torque is smaller than the maximum torque when the vehicle speed becomes equal to or higher than the predetermined first vehicle speed. In this way, it is possible to prevent the lockup clutch engagement side control from being executed at an extremely low speed when the vehicle speed is lower than the first vehicle speed, and to generate a vehicle vibration by the lockup clutch engagement side control at an extremely low speed. Can be prevented in advance. Then, when the vehicle speed becomes equal to or higher than the first vehicle speed, the rotational speed of the internal combustion engine increases to some extent, and the maximum torque that can be generated by the internal combustion engine can be accurately calculated, and the relationship between the required torque and the maximum torque is accurately determined. The lockup clutch engagement side control can be started when the required torque is smaller than the maximum torque after the state can be determined well.

  In the lockup clutch engagement side control, the lockup clutch is controlled to be completely engaged when the required torque is less than a predetermined value smaller than the maximum torque, and the required torque is greater than the maximum torque. The lockup clutch may be controlled to a predetermined slip state when the value is smaller than the predetermined value. In this way, when the required torque is smaller than the predetermined value, the required torque is sufficiently smaller than the maximum torque, so that the required torque can be reliably realized without using the torque amplification action of the torque converter. By determining that the lockup clutch is in the fully engaged state, the fuel efficiency improvement effect can be enhanced. On the other hand, if the required torque is smaller than the maximum torque and greater than or equal to the predetermined value, it is determined that the required torque is relatively close to the maximum torque and the lock-up clutch is controlled to slip so that the torque converter torque amplification The operation can be used to some extent, and the torque that can be output can be given a margin, and the required torque can be reliably realized even when the required torque is relatively close to the maximum torque.

  By the way, when the vehicle decelerates while maintaining the lock-up clutch on the engagement side (completely engaged state or predetermined slip state) in a low speed region where the vehicle speed is relatively low, the rotational speed of the internal combustion engine suddenly decreases and the engine stall (engine stall) May occur.

  As measures against this, as in claim 4, after the start of the lockup clutch engagement side control, in a region where the vehicle speed is equal to or lower than the predetermined second vehicle speed, (1) when the accelerator opening is equal to or lower than the predetermined opening; (2) When the accelerator opening changes to the closing side at a predetermined speed or more, or (3) When the brake pedal is operated, the lock-up clutch engagement side control is stopped and the lock-up clutch is controlled to the released state. You may do it. In this way, when the driver performs an operation of decelerating in the region where the vehicle speed is equal to or lower than the second vehicle speed after the lockup clutch engagement side control is started (the accelerator opening is equal to or less than the predetermined opening). When the accelerator opening changes to the closing side at a predetermined speed or higher, or when the brake pedal is operated), it is determined that the vehicle decelerates in a low speed region below the second vehicle speed, and the lockup clutch is immediately The engagement-side control can be stopped and the lock-up clutch can be released, and the occurrence of engine stall due to the lock-up clutch engagement-side control can be prevented in advance during deceleration in the low speed region.

  Several embodiments embodying the best mode for carrying out the present invention will be described below.

A first embodiment of the present invention will be described with reference to FIGS.
First, a schematic configuration of the entire control system of the engine 11 which is an internal combustion engine will be described with reference to FIG. An air cleaner 13 is mounted on the upstream side of the intake pipe 12 of the engine 11, and an air flow meter 14 for measuring the intake air amount Ga is installed on the downstream side of the air cleaner 13. Further, on the downstream side of the air flow meter 14, a throttle valve 16 whose opening is adjusted by an electric actuator such as a motor 15 and a throttle opening sensor 17 for detecting the opening (throttle opening) TA of the throttle valve 16 are provided. An electronic throttle device 18 is provided.

  An injector 20 is attached to an intake manifold 19 that introduces intake air that has passed through the throttle valve 16 into each cylinder of the engine 11, and a spark plug 21 is attached to a cylinder head of each cylinder of the engine 11. . A crank angle sensor 24 is installed facing the outer periphery of the signal rotor 23 fitted to the crankshaft 22 of the engine 11, and a pulse of the engine rotation speed signal output from the crank angle sensor 24 is transmitted to an engine electronic control circuit (hereinafter referred to as an engine electronic control circuit). The engine speed Ne is detected from the pulse frequency of the engine speed signal.

  On the other hand, the depression amount (accelerator opening) of the accelerator pedal 26 is detected by the accelerator sensor 27, and a voltage signal Ap corresponding to the accelerator opening is taken into the engine ECU 25 via the A / D converter 28. Further, the intake air amount Ga detected by the air flow meter 14 and the voltage signals of the throttle opening TA detected by the throttle opening sensor 17 are also taken into the engine ECU 25 via the A / D converter 28.

  The engine ECU 25 is composed mainly of a microcomputer including a CPU 29, a ROM 30, a RAM 31, and the like, and controls various ignition control routines stored in the ROM 30 by the CPU 29, thereby controlling the ignition timing of the spark plug 21. At the same time, the pulse width of the injection signal applied to the injector 20 via the injector drive circuit 45 is controlled to control the fuel injection amount.

  In addition, the engine ECU 25 executes various throttle control routines stored in the ROM 30 by the CPU 29 so that the throttle opening detected by the throttle opening sensor 17 matches the target throttle opening. The motor 15 of the throttle valve 16 is feedback-controlled by PID control or the like via the circuit 32. When the electronic throttle system is abnormal, the safety circuit 46 provided in the energization path from the motor drive circuit 32 to the motor 15 is operated, and the energization to the motor 15 is kept off. In this state, the throttle opening is held at a predetermined opening in order to enable retreat travel.

  Next, a schematic configuration of the automatic transmission 51 will be described with reference to FIGS. As shown in FIG. 3, an input shaft 53 of a torque converter 52 is connected to the output shaft of the engine 11, and a hydraulically driven transmission gear mechanism 55 (transmission mechanism) is connected to the output shaft 54 of the torque converter 52. Has been. Inside the torque converter 52, a pump impeller 71 and a turbine runner 72 constituting a fluid coupling are provided to face each other, and a stator 73 that rectifies the flow of oil is provided between the pump impeller 71 and the turbine runner 72. It has been. The pump impeller 71 is connected to the input shaft 53 of the torque converter 52, and the turbine runner 72 is connected to the output shaft 54 of the torque converter 52.

  The torque converter 52 is provided with a lockup clutch 56 for engaging or disengaging between the input shaft 53 side and the output shaft 54 side. The output torque of the engine 11 is transmitted to the transmission gear mechanism 55 via the torque converter 52 and is shifted by a plurality of gears (such as planetary gears) of the transmission gear mechanism 55 to be applied to the driving wheels (front wheels or rear wheels) of the vehicle. Communicated.

  The transmission gear mechanism 55 is provided with a plurality of clutches C0, C1, C2 and brakes B0, B1, which are friction engagement elements for switching a plurality of shift stages. As shown in FIG. The gear ratio is switched by switching the engagement / release of C1 and C2 and the brakes B0 and B1 by hydraulic pressure and switching the combination of gears for transmitting power.

  FIG. 4 shows a combination of engagement of the clutches C0, C1, C2 and the brakes B0, B1 of the four-speed automatic transmission, and the mark “O” is held in the engaged state (torque transmission state) at the gear stage. The clutch and brake are shown, and the unmarked state shows the released state. For example, in the throttle depression state of the D range, as the vehicle speed increases, it is upshifted to first speed, second speed, third speed, and fourth speed. In the shift from the first speed to the second speed, B0 is released from the engagement of C0 and B0, and B1 is newly engaged. In the shift from the second speed to the third speed, B1 is released from the engagement of C0 and B1, and C2 is newly engaged. In the shift from the third speed to the fourth speed, C0 is released from the engagement of C0 and C2, and B1 is newly engaged.

  As shown in FIG. 2, the transmission gear mechanism 55 is provided with a hydraulic pump 58 driven by engine power, and a hydraulic control circuit 57 is provided in an oil pan (not shown) that stores hydraulic oil (oil). Is provided. The hydraulic control circuit 57 includes a line pressure control circuit 59, an automatic transmission control circuit 60, a lock-up control circuit 61, a manual switching valve 66, and the like. The hydraulic oil pumped up from the oil pan by the hydraulic pump 58 is controlled by the line pressure. This is supplied to the automatic transmission control circuit 60 and the lockup control circuit 61 via the circuit 59. The line pressure control circuit 59 is provided with a hydraulic pressure control valve (not shown) for controlling the hydraulic pressure from the hydraulic pump 58 to a predetermined line pressure. The automatic transmission control circuit 60 includes a transmission gear mechanism. A plurality of shift hydraulic control valves (not shown) for controlling the hydraulic pressure supplied to the clutches C0, C1, C2 and the brakes B0, B1 are provided. The lockup control circuit 61 is provided with a lockup control hydraulic control valve (not shown) for controlling the hydraulic pressure supplied to the lockup clutch 56.

  Further, a manual switching valve 66 that is switched in conjunction with the operation of the shift lever 65 is provided between the line pressure control circuit 59 and the automatic transmission control circuit 60. When the shift lever 65 is operated to the neutral range (N range) or the parking range (P range), even if the energization of the hydraulic control valve of the automatic transmission control circuit 60 is stopped (OFF), The hydraulic pressure supplied to the transmission gear mechanism 55 is switched by the manual switching valve 66 so that the transmission gear mechanism 55 is in a neutral state.

  On the other hand, the transmission gear mechanism 55 includes a turbine rotation speed sensor 68 that detects a turbine rotation speed Nt that is an input shaft rotation speed of the transmission gear mechanism 55 and an output shaft rotation that detects an output shaft rotation speed No of the transmission gear mechanism 55. A speed sensor 69 is provided. A vehicle speed Vsp is detected based on the output signal of the output shaft rotation speed sensor 69. Further, the brake operation (operation of the brake pedal) is detected by the brake switch 79.

  Output signals of these various sensors and switches are input to an automatic transmission electronic control circuit (hereinafter referred to as “AT-ECU”) 70. The AT-ECU 70 is mainly composed of a microcomputer, and executes various routines stored in a built-in ROM (storage medium), whereby a transmission gear according to a preset shift pattern shown in the shift diagram of FIG. The shift of the hydraulic control valve of the automatic shift control circuit 60 is controlled according to the operating position of the shift lever 65 and the operating conditions (throttle opening, vehicle speed, etc.) so that the shift of the mechanism 55 is executed. By controlling the hydraulic pressure applied to the clutches C0, C1, C2 and the brakes B0, B1 of the gear mechanism 55, as shown in FIG. 4, the clutches C0, C1, C2 and the brakes B0, B1 are engaged. The gear ratio of the transmission gear mechanism 55 is switched by switching the release / release and switching the combination of gears that transmit power.

  As shown in the functional block diagram of FIG. 6, the engine ECU 25 and the AT-ECU 70 function as a power train control device 74, the fuel control unit 75 controls the fuel injection of the injector 20, and the intake control unit 78 controls the electronic throttle device. The intake air amount of the engine 11 is controlled by controlling the throttle opening 18. Further, the transmission control unit 77 controls the automatic transmission control circuit 60 of the automatic transmission 51 to switch the transmission gear ratio of the transmission gear mechanism 55. Further, the lock-up clutch engagement force control unit 76 (lock-up clutch control means) controls the lock-up control circuit 61 of the automatic transmission 51, so that the slip amount of the lock-up clutch 56 (on the output shaft 54 side of the torque converter 52) is controlled. And the input shaft 53 side, i.e., the difference between the turbine rotational speed Nt and the engine rotational speed Ne), the locking force of the lock-up clutch 56 is feedback-controlled so as to match the target value. Lockup clutch complete engagement control for maintaining the fully engaged state and lockup clutch slip control for maintaining the lockup clutch 56 in a predetermined slip state are executed. Alternatively, lockup clutch release control for maintaining the lockup clutch 56 in the released state (disconnected state) is executed.

  Further, the engine ECU 25 and the AT-ECU 70 control the lockup clutch 56 as follows by executing a power train control routine of FIG. 7 described later. As shown in the time chart of FIG. 8, when the vehicle speed Vsp becomes equal to or higher than a predetermined first vehicle speed Vsp1 when the vehicle starts, the current accelerator opening Ap is referred to by referring to the map of the required torque Treq shown in FIG. The required torque Treq (that is, the torque required by the driver) according to the above is calculated, and the maximum torque TM that can be generated by the engine 11 is calculated with reference to the map of the engine torque Te shown in FIG. In the map of engine torque Te in FIG. 10, a map of engine torque Te corresponding to the engine rotational speed Ne is set for each throttle opening TA, and the map at the time of full opening of the throttle opening TA is selected. By calculating the engine torque Te corresponding to the speed Ne1, the maximum torque TM that can be generated by the engine 11 at the current engine speed Ne1 is calculated.

  In this case, for example, as shown by a solid line in FIG. 8, when the accelerator opening Ap is relatively small at the time ta when the vehicle speed Vsp becomes equal to or higher than the first vehicle speed Vsp1, As shown in FIG. 9, the required torque Treq (a) corresponding to the accelerator opening Ap (a) is relatively small. Therefore, the required torque Treq (a) can be generated by the engine 11 as shown in FIG. It becomes smaller than the maximum torque TM. In such a case, it is determined that the required torque Treq (a) can be realized without much amplification of the engine torque Te by the torque converter 52, and the lockup clutch 56 is engaged on the engagement side (completely engaged state or predetermined slip state). The lock-up clutch engagement side control is controlled. As a result, the transmission efficiency of the power of the engine 11 is increased and the fuel consumption is improved without deteriorating the acceleration feeling when the vehicle starts.

  In this lockup clutch engagement side control, when the required torque Treq (a) is less than a predetermined value Ts smaller than the maximum torque TM, lockup clutch complete engagement control is executed and the lockup clutch 56 is fully engaged. To control. On the other hand, when the required torque Treq (a) is smaller than the maximum torque TM and greater than or equal to the predetermined value Ts, lockup clutch slip control is executed to control the lockup clutch 56 to a predetermined slip state.

  On the other hand, for example, as shown by a broken line in FIG. 8, at the time tb when the vehicle speed Vsp becomes equal to or higher than the first vehicle speed Vsp1, the accelerator opening Ap is a relatively large accelerator opening Ap (b). As shown in FIG. 9, the required torque Treq (b) corresponding to the accelerator opening Ap (b) is relatively large, so that the required torque Treq (b) is generated by the engine 11 as shown in FIG. It becomes larger than the maximum possible torque TM. In such a case, it is determined that the required torque Treq (b) cannot be realized unless the engine torque Te is amplified by the torque converter 52, and the lockup clutch release control is executed without executing the lockup clutch engagement side control. Then, the lock-up clutch 56 is controlled to the released state. Thus, an actual torque corresponding to the required torque Treq (b) is generated using the torque amplification action of the torque converter 52, and the acceleration feeling when the vehicle starts is improved.

  Hereinafter, processing contents of the powertrain control routine of FIG. 7 executed by the engine ECU 25 and the AT-ECU 70 will be described.

  The powertrain control routine shown in FIG. 7 is executed at a predetermined cycle. When this routine is started, first, at step 101, the engine speed Ne, the vehicle speed Vsp, the accelerator pedal opening Ap, etc. are read based on the output of various sensors, etc., and then the routine proceeds to step 102 where the vehicle speed Vsp is the first speed. It is determined whether or not the vehicle speed is Vsp1 or higher. The first vehicle speed Vsp1 is set to a minimum vehicle speed at which the vibration of the vehicle does not occur or a slightly higher vehicle speed even when the lockup clutch 56 is controlled to the engagement side (fully engaged state or predetermined slip state). .

  If it is determined in step 102 that the vehicle speed Vsp is lower than the first vehicle speed Vsp1, the process proceeds to step 103, lockup clutch release control is executed, and the lockup clutch 56 is maintained in the released state. Thereafter, the routine proceeds to step 104, the target throttle opening degree TAr corresponding to the current accelerator opening degree Ap is calculated, and then the routine proceeds to step 114, where the actual throttle opening degree TA detected by the throttle opening degree sensor 17 is set as the target throttle opening degree TA. Throttle opening control for feedback control of the motor 15 of the throttle valve 16 is executed so as to match TAR.

  Thereafter, when it is determined in step 102 that the vehicle speed Vsp is equal to or higher than the first vehicle speed Vsp1, the process proceeds to step 105, and a map of the required torque Treq shown in FIG. The required torque Treq (that is, the torque required by the driver) corresponding to the above is calculated. Thereafter, the routine proceeds to step 106, where the map at the time of full opening of the throttle opening TA is selected from the map of the engine torque Te shown in FIG. 10, and the engine torque Te corresponding to the current engine speed Ne1 is calculated. Thus, the maximum torque TM that can be generated by the engine 11 at the current engine speed Ne1 is calculated.

  Thereafter, the routine proceeds to step 107, where it is determined whether or not the required torque Treq is smaller than the maximum torque TM. As a result, when it is determined that the required torque Treq is smaller than the maximum torque TM, it is determined that the required torque Treq can be achieved without amplifying the engine torque Te by the torque converter 52, and the lockup clutch Lock-up clutch engagement side control for controlling 56 to the engagement side (completely engaged state or predetermined slip state) is executed as follows.

  First, in step 108, it is determined whether or not the required torque Treq is equal to or greater than a predetermined value Ts. The predetermined value Ts is set to a value smaller than the maximum torque TM.

  If it is determined in step 108 that the required torque Treq is smaller than the predetermined value Ts (when Treq <Ts), the required torque Treq is sufficiently smaller than the maximum torque TM, so that the torque amplification of the torque converter 52 is performed. Even if the operation is not used, it is determined that the required torque Treq can be surely realized, and the routine proceeds to step 109, where the lock-up clutch complete engagement control is executed, and the slip amount of the lock-up clutch 56 (the output of the torque converter 52). The locking force of the lockup clutch 56 is feedback controlled so that the rotational speed difference between the shaft 54 side and the input shaft 53 side, that is, the difference between the turbine rotational speed Nt and the engine rotational speed Ne is zero. Is maintained in a fully engaged state.

  On the other hand, when it is determined in step 107 that the required torque Treq is smaller than the maximum torque TM and it is determined in step 108 that the required torque Treq is equal to or greater than the predetermined value Ts (when Ts ≦ Treq <TM). Is determined that the required torque Treq is relatively close to the maximum torque TM, and the routine proceeds to step 110 where lock-up clutch slip control is executed to lock the slip amount of the lock-up clutch 56 to the target value. The lock-up clutch 56 is maintained in a predetermined slip state by feedback control of the fastening force of the up clutch 56.

  Thereafter, the routine proceeds to step 111, where the engine corresponding to the current engine speed Ne1 and the target throttle opening TAr is used using the relationship between the engine speed Ne, the throttle opening TA, and the engine torque Te (see FIG. 10). The target throttle opening degree TAr is calculated so that the torque Te matches the required torque Treq.

  Thereafter, the routine proceeds to step 114, where throttle opening control is executed in which the motor 15 of the throttle valve 16 is feedback-controlled so that the actual throttle opening TA matches the target throttle opening TAr.

  On the other hand, if it is determined in step 107 that the required torque Treq is equal to or greater than the maximum torque TM, it is determined that the required torque Treq cannot be realized unless the engine torque Te is amplified by the torque converter 52. Proceeding to step 112, lockup clutch release control is executed to maintain the lockup clutch 56 in the released state.

  Thereafter, the routine proceeds to step 113, where a torque ratio tr according to the ratio (Nt / Ne) between the turbine rotational speed Nt and the engine rotational speed Ne is calculated with reference to the map of the torque ratio tr shown in FIG. Using the relationship between the rotational speed Ne, the throttle opening degree TA, and the engine torque Te (see FIG. 10), the engine torque Te corresponding to the current engine rotational speed Ne1 and the target throttle opening degree TAr is multiplied by the torque ratio tr. The target throttle opening degree TAr is calculated so that the value matches the required torque Treq.

  Thereafter, the routine proceeds to step 114, where throttle opening control is executed in which the motor 15 of the throttle valve 16 is feedback-controlled so that the actual throttle opening TA matches the target throttle opening TAr.

  In the first embodiment described above, when the required torque Treq corresponding to the accelerator opening Ap is smaller than the maximum torque TM that can be generated by the engine 11 when the vehicle starts, the engine torque Te is amplified by the torque converter 52 so much. Since it is determined that the required torque Treq can be realized without the control, the lockup clutch engagement side control for controlling the lockup clutch 56 to the engagement side (completely engaged state or predetermined slip state) is executed. The power transmission efficiency of the engine 11 can be increased to improve fuel efficiency without deteriorating the acceleration feeling when the vehicle is started.

  On the other hand, when the required torque Treq corresponding to the accelerator opening Ap is greater than or equal to the maximum torque TM that can be generated by the engine 11 at the start of the vehicle, the required torque Treq cannot be realized unless the engine torque Te is amplified by the torque converter 52. Thus, since the lockup clutch disengagement control is executed without executing the lockup clutch engagement side control, the required torque Treq can be realized using the torque amplification action of the torque converter 52, and the vehicle Acceleration feeling when starting can be improved.

  In the first embodiment, the lockup clutch engagement side control is executed when the required torque Treq is smaller than the maximum torque TM when the vehicle speed Vsp becomes equal to or higher than the first vehicle speed Vsp1 when the vehicle starts. Therefore, it is possible to prevent the lockup clutch engagement side control from being executed when the vehicle speed Vsp is lower than the first vehicle speed Vsp1, and to cause the vehicle to vibrate due to the lockup clutch engagement side control at the extremely low speed. Can be prevented. Then, the vehicle speed Vsp becomes equal to or higher than the first vehicle speed Vsp1, the engine rotational speed Ne increases to some extent, and the maximum torque TM that can be generated by the engine 11 can be accurately calculated, and the required torque Treq and the maximum torque TM can be calculated. The lockup clutch engagement side control can be started when the required torque Treq is smaller than the maximum torque TM after the magnitude relationship can be accurately determined.

  Further, in the first embodiment, during the lockup clutch engagement side control, if the required torque Treq is less than the predetermined value Ts smaller than the maximum torque TM, the required torque Treq is sufficiently smaller than the maximum torque TM. Since it is determined that the required torque Treq can be reliably achieved without using the torque amplification function of the torque converter 52, the lockup clutch complete engagement control is executed, so that the fuel efficiency improvement effect can be enhanced. .

  On the other hand, when the required torque Treq is smaller than the maximum torque TM and greater than or equal to the predetermined value Ts, it is determined that the required torque Treq is relatively close to the maximum torque TM and the lockup clutch slip control is executed. The torque amplifying function of the torque converter 52 can be used to some extent, and the torque that can be output can be given a margin. Even when the required torque Treq is relatively close to the maximum torque TM, the required torque Treq is reliably realized. can do.

  Next, Embodiment 2 of the present invention will be described with reference to FIG. However, description of parts substantially the same as those in the first embodiment will be omitted or simplified, and parts different from those in the first embodiment will be mainly described.

  When the vehicle decelerates while maintaining the lock-up clutch 56 on the engagement side (completely engaged state or predetermined slip state) in a low speed range where the vehicle speed is relatively low, the engine speed Ne suddenly decreases and engine stall occurs. there's a possibility that.

  As a countermeasure against this, in the second embodiment, a vehicle speed Vsp after the start of lockup clutch engagement side control (lockup clutch complete engagement control or lockup clutch slip control) is executed by executing a power train control routine of FIG. When the accelerator opening degree Ap is less than or equal to the predetermined opening degree Ap0 in a region where the vehicle speed is lower than the predetermined second vehicle speed Vsp2 (that is, when the driver performs an operation to decelerate), the vehicle speed Vsp becomes the second vehicle speed. It is determined that the vehicle decelerates in a low speed region below Vsp2, and the lockup clutch engagement side control is immediately stopped to execute the lockup clutch release control.

  The routine shown in FIG. 12 is obtained by adding steps 115 to 118 to the power train control routine shown in FIG. 7 described in the first embodiment, and the other steps are the same as those shown in FIG. .

  In the powertrain control routine shown in FIG. 12, when the required torque Treq is smaller than the maximum torque TM when the vehicle speed Vsp is equal to or higher than the first vehicle speed Vsp1, lockup clutch complete engagement control or lockup clutch slip control is performed. Execute (Steps 101 to 110). Thereafter, the routine proceeds to step 111, the target throttle opening degree TAr is calculated, and then the routine proceeds to step 115, where throttle opening degree control is executed so that the actual throttle opening degree TA coincides with the target throttle opening degree TAr.

  Thereafter, the routine proceeds to step 116, where it is determined whether or not the vehicle speed Vsp is equal to or lower than the second vehicle speed Vsp2. The second vehicle speed Vsp2 is set to be higher than the first vehicle speed Vsp1. If it is determined in step 116 that the vehicle speed Vsp is less than or equal to the second vehicle speed Vsp2, the routine proceeds to step 117, where the driver decelerates depending on whether the accelerator opening Ap is less than or equal to the predetermined opening Ap0. It is determined whether or not an operation has been performed. This predetermined opening degree Ap0 is set to, for example, an opening degree that is fully closed or in the vicinity thereof.

  If it is determined in step 116 that the vehicle speed Vsp is less than or equal to the second vehicle speed Vsp2, and it is determined in step 117 that the accelerator opening Ap is less than or equal to the predetermined opening Ap0, the vehicle speed Vsp is It is determined that the vehicle decelerates in the low speed region below the vehicle speed Vsp2, and the routine proceeds to step 118, where the lockup clutch engagement side control (lockup clutch complete engagement control or lockup clutch slip control) is immediately stopped and lockup clutch release control is performed. Execute.

  In the second embodiment described above, the vehicle speed Vsp becomes the second vehicle speed Vsp2 when the accelerator opening is less than or equal to the predetermined opening in the region where the vehicle speed is less than or equal to the second vehicle speed after the lockup clutch engagement side control is started. Since it is judged that the vehicle decelerates in the following low speed region, the lockup clutch engagement side control is immediately stopped and the lockup clutch release control is executed, so the lockup clutch engagement side control is performed during deceleration in the low speed region. The occurrence of engine stall can be prevented beforehand.

  In the second embodiment, it is determined whether or not the driver has performed an operation of decelerating depending on whether or not the accelerator opening Ap is equal to or less than the predetermined opening Ap0. The determination of whether or not the operation is performed may be changed as appropriate.

  For example, a routine in which the processing in steps 116 to 118 in the power train control routine in FIG. 12 described in the second embodiment is replaced with the processing in FIG. 13 may be executed. In this case, in step 116, the vehicle speed Vsp is After determining whether or not the vehicle speed is less than or equal to the second vehicle speed Vsp2, in the next step 117a, it is determined whether or not the closing speed of the accelerator opening Ap is greater than or equal to a predetermined speed (the accelerator opening Ap is greater than or equal to the predetermined speed) Whether or not the driver has attempted to decelerate. If it is determined in step 116 that the vehicle speed Vsp is less than or equal to the second vehicle speed Vsp2, and it is determined in step 117a that the closing speed of the accelerator opening Ap is greater than or equal to a predetermined speed, the vehicle speed Vsp is It is determined that the vehicle decelerates in a low speed region equal to or lower than the vehicle speed Vsp2 of No. 2, and the process proceeds to step 118 where the lockup clutch engagement side control is immediately stopped and lockup clutch release control is executed. Even if it does in this way, the substantially same effect as the said Example 2 can be acquired.

  Alternatively, a routine in which the processing in steps 116 to 118 in the power train control routine in FIG. 12 described in the second embodiment is replaced with the processing in FIG. 14 may be executed. Is determined to be less than or equal to the second vehicle speed Vsp2, and then, in the next step 117b, the driver tries to decelerate depending on whether or not the brake switch 79 is on (whether or not the brake pedal is operated). It is determined whether or not an operation has been performed. If it is determined in step 116 that the vehicle speed Vsp is equal to or lower than the second vehicle speed Vsp2, and it is determined in step 117b that the brake switch 79 is ON, the vehicle speed Vsp is a low speed equal to or lower than the second vehicle speed Vsp2. It is determined that the vehicle decelerates in the region, and the process proceeds to step 118 where the lockup clutch engagement side control is immediately stopped and the lockup clutch release control is executed. Even if it does in this way, the substantially same effect as the said Example 2 can be acquired.

  Further, in each of the first to fourth embodiments, the lockup clutch engagement side control is permitted when the vehicle speed is equal to or higher than the first vehicle speed at the start of the vehicle. However, the present invention is not limited to this. Sometimes, a period for permitting the lockup clutch engagement side control may be set based on at least one of the accelerator opening, the engine rotation speed, the vehicle speed, and the like.

It is a schematic block diagram of the whole engine control system in Example 1 of this invention. It is a schematic block diagram of the whole automatic transmission. It is a figure which shows typically the mechanical structure of an automatic transmission. It is a figure which shows the combination of engagement / release of clutch C0-C2 and brake B0, B1 for every gear stage. It is a shift diagram which shows an example of a shift pattern. It is a functional block diagram explaining the function as a power train control apparatus of engine ECU and AT-ECU. 3 is a flowchart illustrating a processing flow of a powertrain control routine according to the first embodiment. It is a time chart which shows the behavior of accelerator opening Ap at the time of vehicle start-up, and vehicle speed Vsp. It is a figure which shows notionally an example of the map of request | requirement torque Treq. It is a figure which shows notionally an example of the map of engine torque Te. It is a figure which shows notionally an example of the map of torque ratio tr. 6 is a flowchart showing a flow of processing of a powertrain control routine of Embodiment 2. 10 is a flowchart showing a part of the processing flow of a powertrain control routine of a modified example (No. 1) of Example 2. 10 is a flowchart showing a part of the processing flow of a powertrain control routine of a modified example (No. 2) of the second embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Engine, 12 ... Intake pipe, 16 ... Throttle valve, 17 ... Throttle opening sensor, 18 ... Electronic throttle device, 20 ... Injector, 24 ... Crank angle sensor, 25 ... Engine ECU, 26 ... Accelerator pedal, 27 ... Accelerator Sensors 51... Automatic transmission 52. Torque converter 55. Transmission gear mechanism (transmission mechanism) 56. Lockup clutch 68. Turbine rotational speed sensor 69. Output shaft rotational speed sensor 70. 74 ... Powertrain control device, 76 ... Lock-up clutch engagement force control unit (lock-up clutch control means), 79 ... Brake switch

Claims (4)

In a vehicle powertrain control device for transmitting the power of an internal combustion engine to a wheel side via a torque converter with a lock-up clutch and a transmission mechanism,
Lockup for executing lockup clutch engagement side control for controlling the lockup clutch to the engagement side when the required torque set according to the accelerator opening at the start of the vehicle is smaller than the maximum torque that can be generated by the internal combustion engine A vehicle powertrain control device comprising clutch control means.   The lockup clutch control means executes the lockup clutch engagement side control when the required torque is smaller than the maximum torque when the vehicle speed becomes equal to or higher than a predetermined first vehicle speed. Item 4. The vehicle powertrain control device according to Item 1.   In the lockup clutch engagement side control, the lockup clutch control means controls the lockup clutch to a fully engaged state when the requested torque is less than a predetermined value smaller than the maximum torque, and the requested torque 3. The vehicle powertrain control device according to claim 1, wherein the lockup clutch is controlled to a predetermined slip state when the torque is smaller than the maximum torque and equal to or greater than the predetermined value. 4.   The lockup clutch control means (1) when the accelerator opening is equal to or less than a predetermined opening in a region where the vehicle speed is equal to or lower than a predetermined second vehicle speed after the lockup clutch engagement side control is started, or (2 ) When the accelerator opening changes to the closing side at a predetermined speed or more, or (3) When the brake pedal is operated, the lockup clutch engagement side control is stopped and the lockup clutch is controlled to the released state. The powertrain control device for a vehicle according to any one of claims 1 to 3.

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