JP2011127715A - Control device and control method for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To appropriately express the effect of fuel consumption improvement while avoiding an engine stall. <P>SOLUTION: When the engaging force of a lock-up clutch requires to be changed (S104) at the start of a vehicle (YES in S100) during the execution of N control (S102), an ECU executes a program including steps of: executing the return control from N control (S106); executing the upper limit guard control of the lock-up clutch (S108); and executing the normal capacity variable control to the lock-up clutch (S112) when it is determined that the return control has completed (YES in S110). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to control of an automatic transmission mounted on a vehicle, and more particularly to control of an automatic transmission in the case of simultaneously executing engagement control of a starting clutch and torque capacity control of a torque converter.

  2. Description of the Related Art Conventionally, an automatic transmission is provided with a lock-up clutch built in a torque converter, in addition to a starting clutch for engaging when starting. By smoothly engaging the starting clutch, the vehicle can start without generating a shock. On the other hand, by engaging the lock-up clutch and increasing the torque capacity of the torque converter, it is possible to suppress loss of driving force in the torque converter when the vehicle starts. Therefore, deterioration of fuel consumption can be suppressed.

  As a vehicle on which such a clutch is mounted, for example, Japanese Patent Laid-Open No. 2004-150531 (Patent Document 1) is provided with a fluid coupling provided with a lock-up clutch and a friction engagement device for power transmission. Disclosed is a vehicle start control device in which a smooth start performance is sufficiently obtained and an engagement shock is suppressed in a vehicle including an automatic transmission. This vehicle start control device is a vehicle start control device including a fluid coupling provided with a lock-up clutch and an automatic transmission provided with a friction engagement device for power transmission. At the time of start, it includes start control means for bringing the friction engagement device into a slip state with the lock-up clutch engaged or semi-engaged.

  According to the vehicle start control device disclosed in the above-mentioned publication, it is possible to perform slip control with higher accuracy than slipping the lock-up clutch, and a smooth start performance of the vehicle can be sufficiently obtained and engagement shock is suppressed. The

  In addition, neutral control is known in which when a predetermined execution condition is satisfied when the vehicle is stopped, the fuel consumption is improved by loosening the engagement force of the starting clutch. When a predetermined return condition is satisfied during the neutral control, the engagement force of the start clutch is increased, and the return control for the start of the vehicle is executed.

JP 2004-150531 A

  By the way, in order to maximize the fuel efficiency improvement effect, it is desirable to increase the torque capacity of the torque converter as much as possible by controlling the engagement force of the lockup clutch when the vehicle starts. On the other hand, when the torque capacity of the torque converter is increased and the engine speed is lower than the engine speed for avoiding engine stall (hereinafter referred to as engine stall guaranteed engine speed), It is more likely to occur. On the other hand, if the torque capacity of the torque converter is unnecessarily reduced, the fuel efficiency improvement effect may be reduced. Therefore, in order to avoid stalling of the engine, it is desirable to keep the engine speed higher than the engine stall guaranteed speed while making the torque capacity as high as possible by feedback control of the engagement force of the lockup clutch.

  However, when the variable displacement control using the lock-up clutch described above and the return control from the neutral control are performed simultaneously, the control diverges and the torque capacity is unnecessarily increased, so that the engine can stall. There is sex. This is because both the variable capacity control and the neutral control perform feedback control based on a common state quantity (for example, the turbine speed).

  The present invention has been made in order to solve the above-described problems, and an object of the present invention is to provide a vehicle control device and a vehicle control method that appropriately expresses an effect of improving fuel efficiency while avoiding engine stall. Is to provide.

  A vehicle control apparatus according to an aspect of the present invention is a vehicle control apparatus for a vehicle on which an automatic transmission including a torque converter and a transmission mechanism and an engine are mounted. The speed change mechanism has a first clutch for engaging when the vehicle starts. The torque converter has a second clutch for changing the torque capacity of the torque converter. The vehicle control device includes a neutral control for performing a neutral control for controlling an engagement force of the first clutch so that the engaged first clutch is disengaged when the first execution condition is satisfied. A return control unit for executing a return control for controlling the engagement force of the first clutch so that the first clutch in the disengaged state returns to the engaged state when the return condition is satisfied, A variable capacity control unit for executing variable capacity control for controlling the engagement force of the second clutch so that the torque capacity matches the torque capacity corresponding to the state of the vehicle when the execution condition is satisfied, a return condition, When the two execution conditions are satisfied at the same time, the second value based on the lower limit value of the engine speed for avoiding engine stall and the current torque of the engine until the return control by the return control unit ends. It calculates the upper limit value of the torque capacity of the latches, and a upper limit guard controller that the torque capacity of the second clutch controls the engaging force of the second clutch so as to vary along the upper limit.

Preferably, the capacity variable control unit executes the capacity variable control after the return control is completed.
More preferably, the variable capacity control unit calculates a correction amount for the control amount for the second clutch when the variable capacity control is being executed. The upper limit guard control unit controls the engagement force of the second clutch using the correction amount.

  More preferably, the second clutch is a lock-up clutch for bringing the input shaft and output shaft of the torque converter into a direct connection state.

  More preferably, the torque converter includes a pump impeller, a turbine runner, and a stator. The second clutch is a clutch for limiting the rotation of at least one of the pump impeller, the turbine runner, and the stator.

  A vehicle control method according to another aspect of the present invention is a vehicle control method for a vehicle on which an automatic transmission including a torque converter and a transmission mechanism and an engine are mounted. The speed change mechanism has a first clutch for engaging when the vehicle starts. The torque converter has a second clutch for changing the torque capacity of the torque converter. The vehicle control method includes a step of executing neutral control for controlling the engaging force of the first clutch so that the engaged first clutch is disengaged when the first execution condition is satisfied; A step of executing return control for controlling the engagement force of the first clutch so that the first clutch in the non-engaged state returns to the engaged state when the condition is satisfied, and torque when the second execution condition is satisfied When the variable variable control for controlling the engagement force of the second clutch so that the capacity matches the torque capacity corresponding to the state of the vehicle, and the return condition and the second execution condition are satisfied at the same time, the return control Until the end of the second clutch, the upper limit value of the torque capacity of the second clutch is calculated based on the lower limit value of the engine speed for avoiding engine stall and the current torque of the engine. And controlling the engaging force of the second clutch such that the torque capacity is varied along the upper limit.

It is a schematic block diagram which shows the power train of the vehicle carrying the vehicle control apparatus which concerns on 1st Embodiment. It is a skeleton figure of the automatic transmission mounted in the vehicle in 1st Embodiment. It is a figure which shows the relationship between the speed ratio in a torque converter, and a capacity | capacitance coefficient. It is a functional block diagram of ECU which is a control device for vehicles concerning a 1st embodiment. It is a flowchart which shows the control structure of the program performed by ECU which is the vehicle control apparatus which concerns on 1st Embodiment. It is a timing chart which shows operation of ECU which is a control device for vehicles concerning a 1st embodiment. It is a skeleton figure of the torque converter mounted in the vehicle in 2nd Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

<First Embodiment>
With reference to FIG. 1, a vehicle 10 equipped with a vehicle control device according to the present embodiment will be described. The vehicle 10 is an FR (Front engine Rear drive) vehicle. The vehicle 10 may be a vehicle other than FR.

  Vehicle 10 includes an engine 100, an automatic transmission 200, an ECU (Electronic Control Unit) 300, wheels 400, a differential gear 402, a drive shaft 404, and a propeller shaft 406. The vehicle control apparatus according to the present embodiment is realized by ECU 300.

  Engine 100 is an internal combustion engine that burns an air-fuel mixture of fuel injected from an injector (not shown) and air sucked from air cleaner 104 via intake passage 102 in a combustion chamber of a cylinder. The piston in the cylinder is pushed down by the combustion, and the crankshaft is rotated. The power of the engine 100 is transmitted to the automatic transmission 200 via the crankshaft.

  The flow rate of air sucked from the air cleaner 104 is adjusted by the throttle valve 108. The throttle valve 108 operates using the throttle motor 110 as a power source. The throttle motor 110 is driven based on a control signal from the ECU 300.

  Automatic transmission 200 is connected to the crankshaft of engine 100. The automatic transmission 200 changes the rotation speed of the crankshaft to a desired rotation speed in accordance with the traveling state of the vehicle. In the present embodiment, automatic transmission 200 will be described as a stepped automatic transmission that changes the gear ratio stepwise in accordance with the running state of the vehicle, but is limited to a stepped automatic transmission. For example, it may be a continuously variable automatic transmission that continuously changes the gear ratio according to the running state of the vehicle.

  Automatic transmission 200 includes a transmission mechanism 202, a torque converter 204, and a hydraulic circuit 206. A lockup clutch 216 is provided inside the torque converter 204. The lock-up clutch 216 brings the input shaft and the output shaft of the torque converter 204 into a directly connected state when it is in an engaged state, and cancels the directly connected state when it is in a disengaged state. In the present embodiment, the engaged state means a state where the lockup clutch 216 is completely engaged, and the non-engaged state includes a half-engaged state and a released state of the lockup clutch 216.

  The lockup clutch 216 is engaged, released, or semi-engaged by the hydraulic pressure supplied from the hydraulic circuit 206. The ECU 300 controls the hydraulic pressure supplied from the hydraulic circuit 206 to the lockup clutch 216 using various solenoids.

  The output shaft of the automatic transmission 200 is connected to the differential gear 402 via the propeller shaft 406. A drive shaft 404 is connected to the differential gear 402 by spline fitting or the like. Power from the automatic transmission 200 is transmitted to the left and right wheels 400 via the propeller shaft 406 and the drive shaft 404.

  The ECU 300 includes an air flow meter 106, a throttle opening sensor 112 of the throttle valve 108, an accelerator position sensor 302, a stop lamp switch 304, a wheel speed sensor 308, a position switch 310 of a shift lever 312 and an engine speed. The sensor 314, the input shaft rotational speed sensor 316, and the output shaft rotational speed sensor 318 are connected via a harness or the like.

  The air flow meter 106 is provided on the upstream side of the intake passage 102 with respect to the throttle valve 108. The air flow meter 106 detects a flow rate of air sucked from the air cleaner 104 (hereinafter referred to as an intake air amount Ga). The air flow meter 106 transmits a signal indicating the intake air amount Ga to the ECU 300.

  The throttle opening sensor 112 detects the opening of the throttle valve 108 (hereinafter referred to as the throttle opening Th) whose opening is adjusted by the throttle motor 110. The throttle opening sensor 112 transmits a signal indicating the throttle opening Th to the ECU 300.

  The accelerator position sensor 302 detects the amount of depression of an accelerator pedal (not shown). Accelerator position sensor 302 transmits a signal indicating the amount of depression of the accelerator pedal to ECU 300.

  The stop lamp switch 304 transmits an ON signal indicating that the brake pedal has been depressed to the ECU 300 when the stroke amount of a brake pedal (not shown) is equal to or greater than a predetermined amount. Instead of the stop lamp switch 304, a stroke sensor that detects the stroke amount of the brake pedal may be used. In this case, ECU 300 may determine that the brake pedal has been depressed when the stroke amount received from the stroke sensor is equal to or greater than a predetermined amount.

  Wheel speed sensor 308 detects the number of rotations of drive shaft 404. Wheel speed sensor 308 transmits a signal indicating the number of rotations of drive shaft 404 to ECU 300. ECU 300 calculates the speed of the vehicle based on the received rotational speed of drive shaft 404.

  The position switch 310 detects the position of the shift lever 312. The shift lever 312 is provided to be movable along a shift gate having a predetermined shape. The position switch 310 transmits a signal indicating the position of the shift lever 312 on the shift gate to the ECU 300.

  ECU 300 controls automatic transmission 200 such that the shift range of automatic transmission 200 matches the shift range corresponding to the position of shift lever 312. The shift range includes, for example, a drive (D) range, a neutral (N) range, a reverse (R) range, and a parking (P) range.

  Engine speed sensor 314 detects the speed of the output shaft (crankshaft) of engine 100 (hereinafter referred to as engine speed NE). The engine speed sensor 314 transmits a signal indicating the engine speed NE to the ECU 300.

  Input shaft rotational speed sensor 316 detects the input shaft rotational speed of automatic transmission 200 (hereinafter referred to as turbine rotational speed NT). Input shaft rotation speed sensor 316 transmits a signal indicating turbine rotation speed NT to ECU 300.

  The output shaft speed sensor 318 detects the output shaft speed NO of the automatic transmission 200. Output shaft rotational speed sensor 318 transmits a signal indicating output shaft rotational speed NO to ECU 300.

  The output shaft of engine 100 is connected to the input shaft of torque converter 204, and the output shaft of torque converter 204 is connected to the input shaft of transmission mechanism 202. Therefore, the rotation speed of the output shaft of engine 100 is the same as the rotation speed of the input shaft of torque converter 204. Further, the input shaft rotation speed of the transmission mechanism 202 is the same as the rotation speed of the output shaft of the torque converter 204.

  The ECU 300 includes a memory 306 such as a RAM (Random Access Memory) or a ROM (Read Only Memory), and includes an air flow meter 106, a throttle opening sensor 112, an accelerator position sensor 302, a stop lamp switch 304, a wheel speed sensor 308, and a position switch. 310, based on the signals sent from the engine speed sensor 314, the input shaft speed sensor 316, the output shaft speed sensor 318, and the like, the map and the program stored in the memory 306, Control the equipment so that

  When the driver moves the shift lever 312 along the shift gate to a position corresponding to the D range, and the D range is selected as the shift range of the automatic transmission 200, the ECU 300 corresponds to the traveling state of the vehicle. The automatic transmission 200 is controlled so that the selected gear position is selected.

  Alternatively, when the driver moves the shift lever 312 to a position corresponding to the N range and the N range is selected as the shift range of the automatic transmission 200, the ECU 300 causes the automatic transmission 200 to be in the neutral state (power The automatic transmission 200 is controlled so that the transmission is cut off.

  The configuration of the automatic transmission 200 will be described in detail with reference to FIG. Torque converter 204 includes a pump impeller 210, a stator 212, a turbine runner 214, a lockup clutch 216, and a one-way clutch 220.

  The pump impeller 210 is connected to an input shaft 218 connected to the crankshaft. The turbine runner 214 is connected to the output shaft 222. The stator 212 is provided between the pump impeller 210 and the turbine runner 214.

  The one-way clutch 220 limits the rotation direction of the stator 212 to one direction. The one-way clutch 220 includes an outer race 224 and an inner race 226. The outer race 224 of the one-way clutch 220 is fixed to the gear case 228, and the inner race 226 is connected to the stator 212.

  The torque converter 204 is filled with hydraulic oil. By changing the direction in which the hydraulic oil flows by the stator 212 when the pump impeller 210 is rotated by the power of the engine and the torque is transmitted by the hydraulic oil flowing from the pump impeller 210 toward the turbine runner 214. Torque input to the input shaft 218 of the torque converter 204 is increased and transmitted to the output shaft 222. The detailed operating principle of the torque converter 204 is a well-known technique and will not be described in detail.

There is a torque capacity coefficient C as an element representing the performance of the torque converter 204. The torque capacity coefficient C is expressed by torque capacity coefficient C = torque required to rotate the input shaft / (input shaft speed) ² .

  When the lockup clutch 216 is engaged, the input shaft 218 and the output shaft 222 of the torque converter 204 are directly connected, and when the lockup clutch 216 is released, the direct connection state between the input shaft 218 and the output shaft 222 is eliminated. To do.

  The transmission mechanism 202 is a Simpson gear train, and includes a first set 240 of planetary gear mechanisms, a second set 250 of planetary gear mechanisms, an output shaft 230, a B1 brake 260 fixed to the gear case 228, and B2. A brake 262, a C1 clutch 264, and a C2 clutch 266 are included. The transmission mechanism 202 is not limited to a Simpson type gear train, and may be another type of gear train.

  The first set 240 and the second set 250 are both single-pinion type planetary gear mechanisms. The first set 240 includes a first sun gear 242, a first pinion gear 244, a first ring gear 246, and a first carrier 248.

  First sun gear 242 is coupled to output shaft 222 of torque converter 204 with C2 clutch 266 interposed. Further, the rotation of the first sun gear 242 is restricted when the B2 brake 262 is engaged. The first pinion gear 244 is rotatably supported by the first carrier 248. First pinion gear 244 meshes with first sun gear 242 and first ring gear 246. First ring gear 246 is coupled to output shaft 222 of torque converter 204 with C1 clutch 264 interposed. The first carrier 248 is connected to the second ring gear 256 of the second set 250 and the output shaft 230 of the speed change mechanism 202.

  The second set 250 includes a second sun gear 252, a second pinion gear 254, a second ring gear 256, and a second carrier 258.

  Second sun gear 252 is connected to first sun gear 242. Therefore, the rotation of the second sun gear 252 is restricted when the B2 brake 262 is engaged. The second pinion gear 254 is rotatably supported by the second carrier 258. Second pinion gear 254 meshes with second sun gear 252 and second ring gear 256. The second carrier 258 is connected to the B1 brake 260. Therefore, the rotation of the second carrier 258 is restricted when the B1 brake 260 is engaged. Second ring gear 256 is connected to first carrier 248 and output shaft 230 of transmission mechanism 202.

  In the speed change mechanism 202 having the above-described configuration, when at least both the C1 clutch 264 and the C2 clutch 266 are opened, the automatic transmission 200 causes the power of the engine 100 to be applied to the output shaft 230 of the speed change mechanism 202. A state where no power is transmitted, that is, a power cut-off state (hereinafter referred to as a neutral state) is established.

  On the other hand, when at least one of the B1 brake 260, the B2 brake 262, the C1 clutch 264, and the C2 clutch 266 is engaged, any one of a plurality of shift speeds (for example, the fourth speed) is changed. A step is formed.

  In the present embodiment, the C1 clutch 264 is engaged when the gear position (first speed) when the vehicle starts is formed.

  In the vehicle having such a configuration, ECU 300 executes neutral control (hereinafter referred to as N control) when a predetermined execution condition is satisfied for the state of the vehicle. N control refers to control that causes the engaged C1 clutch 264 to be in a disengaged state.

  The predetermined execution condition is, for example, a condition in which the accelerator is off, the stop lamp switch 304 is on, the brake master cylinder pressure is a predetermined value or more, and the vehicle speed is a predetermined value or less. The predetermined execution conditions are not particularly limited to the above-described conditions.

  Further, ECU 300 executes return control from N control when a return condition predetermined for the state of the vehicle is satisfied. The return control is control for returning the non-engaged C1 clutch 264 to the engaged state.

  The predetermined return condition may be, for example, a condition that the above-described predetermined execution condition is not satisfied, or control hunting for each threshold value of the above-described predetermined execution condition. A new threshold value that does not occur and has a certain difference may be used as a condition.

  The ECU 300 determines that the return control is completed when the C1 clutch 264 returns to the engaged state. ECU 300 determines whether or not C1 clutch 264 has returned to the engaged state based on output shaft rotational speed NO of automatic transmission 200 and turbine rotational speed NT. For example, ECU 300 synchronizes the turbine rotational speed converted from output shaft rotational speed NO with turbine rotational speed NT detected by input shaft rotational speed sensor 316 (that is, the absolute value of the difference between the two is a predetermined value). In the following case), it is determined that the return control is completed when the C1 clutch 264 returns to the engaged state. Alternatively, ECU 300 may determine that the return control has been completed when the hydraulic control amount of C1 clutch 264 is equal to or greater than a predetermined value.

  Further, ECU 300 executes variable capacity control for increasing the torque capacity in torque converter 204 as much as possible in accordance with the state of the vehicle. In the present embodiment, the control for increasing the torque capacity in torque converter 204 is performed by increasing the engagement force of lockup clutch 216. However, when the torque capacity is increased unnecessarily, the engine 100 may stall. Therefore, ECU 300 feedback-controls the engagement force of lockup clutch 216 based on engine speed NE and turbine speed NT so that engine speed NE does not fall below engine stall guaranteed speed nest.

  The engine stall guaranteed rotational speed nest is a lower limit value of the range of the engine rotational speed NE that can maintain the rotation of the engine 100 even when a disturbance or the like occurs during the execution of the control for increasing the torque capacity and can avoid the stall. is there. The engine stall guaranteed rotational speed nest is a rotational speed lower than the normal idle rotational speed, and varies depending on engine characteristics and displacement.

  When the vehicle starts, the above-described return control and variable capacity control may be activated at the same time. In such a case, the control is diverged, and the engine 100 may stall due to an inappropriate increase in torque capacity. This is because both the return control and the variable displacement control are feedback controlled based on the turbine speed NT.

  In addition, it is conceivable that the control amount of either one of the return control and the variable capacity control is made constant and the other control is stabilized. For example, the control amount of the variable capacity control is set constant. In this case, if the torque capacity at this time is large, the engine 100 may stall due to a disturbance or the like, and if the torque capacity at this time is small, the fuel efficiency improvement effect may be reduced. Therefore, in order to reliably avoid the engine 100 stall, it is necessary to set a torque capacity with a small fuel efficiency improvement effect.

  Therefore, in the present embodiment, when the return condition and the variable capacity control execution condition are satisfied at the same time, ECU 300 determines the amount of change in control amount and control amount of lockup clutch 216 until the return control is completed. The engagement force of the second clutch is controlled so that one of the two is constant, and the upper limit value of the torque capacity of the lockup clutch 216 based on the engine stall guaranteed rotational speed nest and the current torque of the engine 100 And the engaging force of the lockup clutch 216 is controlled so that the torque capacity of the lockup clutch 216 changes along the upper limit value.

  FIG. 3 shows a functional block diagram of ECU 300 that is the vehicle control apparatus according to the present embodiment. The ECU 300 includes a start determination unit 352, an N control execution determination unit 354, an engagement determination unit 356, a correction amount calculation unit 358, a return control unit 360, an upper limit guard control execution unit 362, and an end determination unit 364. And a normal control execution unit 366.

  The start determination unit 352 determines whether or not the vehicle is starting. Specifically, the start determination unit 352 is one of the case where the stop lamp switch 304 is turned off, the accelerator pedal is depressed, and the vehicle speed is higher than a predetermined speed (for example, zero). When it corresponds to, it determines with it being the time of the start of a vehicle. Note that the start determination unit 352 may turn on a start determination flag, for example, when it is determined that the vehicle is starting.

  The N control execution determination unit 354 determines whether or not N control is being executed. Specifically, the N control execution determination unit 354 is executing the N control when a predetermined execution condition for the N control is satisfied and before the return control is completed. Is determined. For example, the N control execution determination unit 354 is turned on when a predetermined execution condition for N control is satisfied, and is being executed based on the state of the N control execution flag that is turned off when the return control is completed. It may be determined whether or not. Note that the N control execution determination unit 354 may turn on the execution determination flag when it is determined that the N control is being executed, for example.

  The engagement determination unit 356 determines whether or not the engagement force of the lockup clutch 216 needs to be changed when the variable capacity control is executed. The variable capacity control is executed when the conditions regarding the torque of the engine 100 and the depression amount of the accelerator pedal are satisfied. At this time, for example, in the low torque region of engine 100 or the like, since the optimum operation is possible only with torque converter 204, the engagement force of lockup clutch 216 is not changed. On the other hand, in the high torque region of engine 100 or the like, the engagement force of lockup clutch 216 is changed when the fuel efficiency improvement effect cannot be exhibited only by torque converter 204.

  That is, engagement determination unit 356 determines whether or not it is necessary to change the engagement force of lockup clutch 216 when executing variable capacity control based on the torque of engine 100 and the amount of depression of the accelerator pedal. The torque of the engine 100 can be estimated from, for example, the intake air amount, throttle opening, fuel injection amount, ignition timing, and intake / exhaust valve opening / closing timing.

  The engagement determination unit 356 determines that the engagement force of the lockup clutch 216 needs to be changed when the shared torque capacity of the lockup clutch 216 calculated by the upper limit guard control execution unit 362 described above is greater than zero. You may make it do.

  Further, for example, when it is determined that the engagement force of the lockup clutch 216 needs to be changed, the engagement determination unit 356 may turn on the engagement determination flag.

  The correction amount calculation unit 358 calculates the correction amount of the control amount of the lockup clutch 216 when the N variable control is not performed and the variable capacity control is executed. Specifically, the correction amount calculation unit 358 uses the theoretical slip amount (the absolute value of the difference between the engine speed NE and the turbine speed NT) with respect to the control amount as a target value, and the actual slip amount with respect to the control amount. The control amount (hydraulic pressure command value) is decreased when the value is smaller than the target value, or the control amount is increased when the actual slip amount with respect to the control amount is larger than the target value, and the actual slip amount is set to the target value. The amount of change in the control amount when matched with is calculated as a correction amount. By controlling the above-mentioned correction amount for the control amount of the lockup clutch 216 not only when the variable displacement control is executed but also when the upper limit guard control is executed, the influence of variations in hydraulic pressure and torque converter performance is suppressed. can do. As a result, the fuel efficiency improvement effect by changing the torque capacity can be generated more effectively. Preferably, the correction amount is calculated in a state where there is no disturbance such as a user operation or a shift. Therefore, a condition that there is no user operation or a condition that no shift is performed may be included as one of the correction execution conditions.

  The correction amount calculation unit 358 determines the control amount of the lockup clutch 216 when, for example, the start determination flag is on, the execution determination flag is off, and the engagement determination flag is on. The correction amount may be calculated. The correction amount calculation unit 358 calculates the correction amount of the control amount of the lockup clutch 216 during slip control of the lockup clutch 216, which is executed when a predetermined condition is satisfied for the running state of the vehicle. It may be. The predetermined condition is, for example, a condition regarding the throttle opening degree Th (or the accelerator pedal depression amount) and the vehicle speed (or the output shaft rotational speed NO). The correction amount calculation unit 358 may store the calculated correction amount in the memory 306.

  The return control unit 360 executes return control from the N control when the vehicle is starting and the N control is being executed. The return control unit 360 increases the engagement force of the C1 clutch 264 to return the C1 clutch 264 to the engaged state. Specifically, the return control unit 360 executes initial control, sweep control, and completion control for the control hydraulic pressure of the C1 clutch 264, for example. In the initial control, the return control unit 360 is output until a predetermined period of time has elapsed, and in the sweep control, a predetermined period is set with an oil pressure lower than the initial oil pressure as an initial value. The control hydraulic pressure is increased at a predetermined rate of increase until the time has elapsed, and when the turbine rotational speed NT and the turbine rotational speed converted from the output shaft rotational speed NO are synchronized (the absolute value of the differential rotational speed is determined in advance). In the completion control, the control hydraulic pressure is increased to the control hydraulic pressure corresponding to the engaged state (when the value becomes equal to or less than a predetermined value).

  Note that the return control unit 360 may execute the return control when, for example, the start determination flag is on and the execution determination flag is on.

  The upper limit guard control execution unit 362 is at the time of starting the vehicle, is executing N control, needs to change the engagement force when executing torque capacity control, and performs return control from N control. Torque, the total torque capacity coefficient of the torque converter 204 including the shared torque capacity coefficient of the lockup clutch 216 does not exceed the upper limit value Cst of the torque capacity coefficient that can avoid the stall of the engine 100. The upper limit value Clu of the capacity coefficient is set. The upper limit guard control execution unit 362 controls the engagement force of the lockup clutch 216 so that the shared torque capacity coefficient of the lockup clutch 216 changes along the set upper limit value Clu. Hereinafter, a method of calculating the upper limit value Clu of the shared torque capacity coefficient of the lockup clutch 216 will be described.

  FIG. 4 shows a torque capacity coefficient performance curve of a general torque converter. The vertical axis in FIG. 4 indicates the torque capacity coefficient C. The horizontal axis in FIG. 4 indicates the speed ratio e.

The torque capacity coefficient C is determined by the speed ratio e. The speed ratio e is expressed by an equation of speed ratio e = turbine speed NT / engine speed NE. The torque capacity coefficient C is expressed by an equation of torque capacity coefficient C = engine torque Te / (engine speed NE) ² .

In this case, the torque capacity coefficient Cst necessary for avoiding the stall of the engine 100 is represented by the torque capacity coefficient Cst = the current engine torque Te1 / (Enst guaranteed speed Nest) ² . At this time, the current speed ratio e1 is represented by the current speed ratio e1 = the current turbine speed NT1 / Enst guaranteed speed Nest, and the current torque capacity coefficient Ctc is determined.

  When the torque capacity coefficient Cst necessary for avoiding the engine 100 stall is equal to the current torque capacity coefficient Ctc (Cst = Ctc), a torque capacity capable of avoiding the engine 100 stall only by the torque converter 204 is ensured. The maximum fuel efficiency is obtained. In this case, the shared torque capacity coefficient of the lockup clutch 216 is zero.

  On the other hand, when the current engine torque Te1 increases in accordance with an increase in the accelerator pedal depression amount of the driver, the torque capacity coefficient Cst necessary for avoiding the stall of the engine 100 is the current torque capacity coefficient Ctc. Therefore, in order to maintain the fuel efficiency improvement effect while avoiding the stall of the engine 100, the engagement force of the lockup clutch 216 is increased and the shared torque capacity coefficient of the lockup clutch 216 is increased. Therefore, the torque capacity coefficient of the entire torque converter 204 needs to be Cst.

  Therefore, the upper limit value Clu of the shared torque capacity coefficient of the lockup clutch 216 is calculated from the equation: upper limit value Clu = torque capacity coefficient Cst−torque capacity coefficient Ctc.

Assuming that the shared torque that the torque converter 204 is responsible for at the current speed ratio e1 is the shared torque Tetc, the current torque capacity coefficient Ctc = shared torque Tetc / (Enst guaranteed speed Nest) ² . Therefore, the upper limit value Clu is represented by the equation: upper limit value Clu = (current engine torque Te1−shared torque Tetc) / (engine stall guaranteed rotational speed nest) ² . Therefore, the upper limit value Telu of the shared torque of the lockup clutch 216 can be calculated by the equation: upper limit value Telu = current engine torque Te1−shared torque Tec.

  In the present embodiment, upper limit value Clu is not constant. For example, as input torque increases, upper limit value Telu or upper limit value Clu increases. Further, when the rotational speed of the input shaft 218 of the torque converter 204 increases and the speed ratio decreases, the torque capacity coefficient Ctc of the torque converter 204 increases, so the upper limit value Telu or the upper limit value Clu decreases.

  Upper limit guard control execution unit 362 performs hydraulic pressure so that the difference between torque capacity coefficient Cst necessary for avoiding engine 100 stall and torque capacity coefficient Ctc of current torque converter 204 varies along upper limit value Clu. When the command value is the control amount, the hydraulic pressure command value for achieving the upper limit value Telu is output as the control amount, and when the torque capacity is the control amount, the Telu is output as the control amount.

  The upper limit guard control execution unit 362 executes the control of the lockup clutch 216 described above when, for example, the start determination flag, the execution determination flag, and the engagement determination flag are all on and the return control is executed. You may make it do. Further, when the correction amount is calculated by the correction amount calculation unit 358 and stored in the memory 306 or the like, the upper limit guard control execution unit 362 controls the engagement force of the lockup clutch 216 in consideration of the correction amount. To do.

  The upper limit guard control execution unit 362 performs the upper limit guard control when the shared torque capacity coefficient of the lockup clutch 216 cannot be changed along the above-described upper limit value Clu according to the state of the vehicle 10. Instead, the lockup clutch 216 may be controlled so as to maintain a state where the torque capacity has a constant capacity.

  For example, the upper limit guard control execution unit 362 controls the engagement force of the lockup clutch 216 so that the control amount of the lockup clutch 216 becomes constant (a predetermined value or a value corresponding to the state of the vehicle).

  Alternatively, the upper limit guard control execution unit 362 keeps the amount of increase or decrease of the control amount constant in order to make the amount of change in the slip amount of the lockup clutch 216 constant (according to a predetermined value or a vehicle state) The engagement force of the lock-up clutch 216 is controlled so as to be (value).

  The end determination unit 364 determines whether or not the return control has ended after the return control from the N control is started. The end determination unit 364 returns when the turbine rotational speed NT and the turbine rotational speed converted from the output shaft rotational speed NO are synchronized (when the absolute value of the differential rotational speed is equal to or lower than a predetermined value). It may be determined that the control has ended, or it may be determined that the return control has ended when the control amount is equal to or greater than a predetermined value.

  Note that the end determination unit 364 may turn on the end determination flag when it is determined that the return control from the N control has ended, for example.

  The normal control execution unit 366 is at the time of vehicle start and not during N control but only when torque capacity control is executed, or at the time of vehicle start and during N control, and the lockup clutch 216. When the return control from the N control is executed and the return control is completed, normal torque capacity control is executed.

  In normal torque capacity control, the target value of the slip amount is set so that the maximum fuel efficiency improvement effect is exhibited, and the engagement force of the lockup clutch 216 is fed back so that the actual slip amount matches the target value. It means to control.

  The normal control execution unit 366 calculates the shared torque of the lockup clutch 216 according to the running state of the vehicle 10 in normal torque capacity control, and the engagement force of the lockup clutch 216 so as to achieve the calculated shared torque. To control.

  Note that the normal control execution unit 366 uses, for example, a speed ratio region in which the loss of the torque converter such as a coupling point is suppressed with respect to the target driving force of the vehicle, and the fuel consumption efficiency of the engine 100 is improved. The shared torque of the lockup clutch 216 may be calculated based on a good operating region (engine torque, engine speed).

  In the present embodiment, a start determination unit 352, an N control execution determination unit 354, an engagement determination unit 356, a correction amount calculation unit 358, a return control unit 360, an upper limit guard control execution unit 362, and an end determination The unit 364 and the normal control execution unit 366 will be described as functioning as software that is realized when the CPU of the ECU 300 executes a program stored in the memory 306, but is realized by hardware. You may do it. Such a program is recorded on a storage medium and mounted on the vehicle.

  With reference to FIG. 5, a control structure of a program executed by ECU 300 that is the vehicle control apparatus according to the present embodiment will be described.

  In step (hereinafter, step is referred to as S) 100, ECU 300 determines whether or not the vehicle is starting. If it is time to start the vehicle (YES in S100), the process proceeds to S102. If not (NO in S100), the process returns to S100 and waits until the vehicle starts.

  In S102, ECU 300 determines whether or not N control is being executed. If N control is being executed (YES in S102), the process proceeds to S104. If not (NO in S102), the process proceeds to S118.

  In S104, ECU 300 determines whether or not the engagement force needs to be changed. If it is determined that the engagement force needs to be changed (YES in S104), the process proceeds to S106. If not (NO in S104), the process proceeds to S114.

  In S106, ECU 300 executes return control from N control. In S108, the ECU performs upper limit guard control on lockup clutch 216. Since the upper limit guard control is as described above, detailed description thereof will not be repeated.

  In S110, ECU 300 determines whether or not the return control from the N control has ended. If it is determined that the return control from the N control has ended (YES in S110), the process proceeds to S112. If not (NO in S110), the process returns to S108.

  In S112, ECU 300 executes normal displacement variable control for lockup clutch 216. In S114, ECU 300 executes return control from N control. In S116, ECU 300 determines whether or not the return control from the N control has ended. If return control from N control has ended (YES in S116), this process ends. If not (NO in S116), the process proceeds to S114.

  In S118, ECU 300 determines whether or not the engagement force needs to be changed. If it is determined that the engagement force needs to be changed (YES in S118), the process proceeds to S120. If not (NO in S118), this process ends. In S120, ECU 300 calculates a correction amount for the control amount of lockup clutch 216. Since the correction amount calculation method is as described above, detailed description thereof will not be repeated.

  The operation of ECU 300 that is the vehicle control apparatus according to the present embodiment based on the above-described structure and flowchart will be described with reference to FIG.

  In the upper part of FIG. 6, the vertical axis indicates the torque capacity coefficient of the lockup clutch, and the horizontal axis indicates time. In the lower part of FIG. 6, the vertical axis represents engine torque, and the horizontal axis represents time.

  For example, a case is assumed in which neutral control is executed in a stopped vehicle because a predetermined execution condition is satisfied. At this time, ECU 300 controls the engagement force of C1 clutch 264 so as to be in a half-engaged state.

  When the driver depresses the accelerator pedal at time T (1), ECU 300 is at the start of the vehicle (YES in S100) and N control is being executed (YES in S102). ), It is determined whether or not the lock-up clutch 216 needs to be engaged (S104).

  When engagement of lockup clutch 216 is required (YES in S104), return control from N control is executed (S106), and upper limit guard control is executed for lockup clutch 216 (S108).

  As shown in FIG. 6, when the accelerator pedal is depressed by the driver, the engine torque increases. The upper limit value Clu also increases as the engine torque increases. Therefore, when the upper limit guard control is executed (the solid line in FIG. 6), the shared torque capacity coefficient of the lockup clutch 216 is calculated along with the change in the upper limit value Clu, so that stalling of the engine 100 is avoided. In addition, the effect of improving fuel efficiency can be generated effectively. On the other hand, when the torque capacity is held constant (broken line in FIG. 6), the torque capacity is limited to a shared torque capacity coefficient for avoiding stalling of the engine 100 in the low torque region. Compared with the case where the upper limit guard control is executed, the effect of improving the fuel efficiency cannot be effectively generated.

  When it is determined that the return control has been completed (YES in S110), normal variable capacity control is executed for lockup clutch 216 (S112).

  On the other hand, when the vehicle is starting (YES in S100), N control is not being executed (NO in S102), and the engagement force of lockup clutch 216 needs to be changed (YES in S118). ), A control amount correction amount for the lockup clutch 216 is calculated (S120). Then, normal variable capacity control is executed for the lockup clutch 216 (S112).

  Further, when the vehicle is starting (YES in S100), N control is being executed (YES in S102), and it is not necessary to change the engagement force of lockup clutch 216 (NO in S104). ), The return control from the N control is executed (S114), and if it is determined that the return control has ended (YES in S116), the process ends.

  As described above, according to the vehicle control device of the present embodiment, the return control is stabilized by executing the upper limit guard control for the lockup clutch during the return control from the N control. The torque capacity can be increased as much as possible while avoiding engine stall. By stably executing the return control, it is possible to quickly return from the N control. Also, by increasing the torque capacity as much as possible, in addition to the loss due to slip that occurs in the torque converter, the fuel consumption is improved with respect to the energy required to offset the inertia required for the increase in engine speed due to slip. An effect can be generated effectively.

  Furthermore, the control accuracy can be improved by considering the correction amount with respect to the control amount of the lockup clutch when the upper limit guard is executed. Thereby, the fuel efficiency improvement effect can be further improved. Therefore, it is possible to provide a vehicle control device and a vehicle control method that appropriately achieve an effect of improving fuel efficiency while avoiding engine stall.

  For the control of the lock-up clutch, it is necessary to consider drivability, fuel consumption, and avoidance of engine stall. However, by applying the present invention, it is not necessary to consider the stall of engine 100. Instead, it is possible to control the lock-up clutch with priority on drivability, such as suppressing sudden fluctuations in vehicle acceleration.

  In the present embodiment, the upper limit guard control is executed for the lockup clutch while performing the feedback control for the return control. However, the present invention is not particularly limited to this. While performing feedback control on the engagement force of the up clutch, the engine stall is avoided for the control amount of the C1 clutch with respect to the return control, and the upper limit value of the control amount of the C1 clutch for generating the fuel efficiency improvement effect is calculated. Then, the engagement force of the C1 clutch may be controlled so as to change along the calculated upper limit value. Which of the return control and the control of the engagement force of the lockup clutch is the feedback control and which is the upper limit guard control is determined in consideration of the heat resistance capacity and controllability of the C1 clutch and the lockup clutch, for example. May be.

<Second Embodiment>
Compared with the vehicle 10 equipped with the vehicle control device according to the first embodiment, the vehicle equipped with the vehicle control device according to the present embodiment has a torque converter 204 instead of the one-way clutch 220 and a Cs clutch. 232 is different. About another structure, it is the same as the vehicle 10 carrying the vehicle control apparatus which concerns on 1st Embodiment. Therefore, detailed description thereof will not be repeated.

  As shown in FIG. 7, the stator 212 is connected to the gear case 228 with a Cs clutch 232 interposed therebetween. Therefore, when the Cs clutch 232 is in the engaged state, the stator 212 is fixed to the gear case 228 and its rotation is restricted. On the other hand, when the Cs clutch 232 is in the disengaged state or the half-engaged state, the stator 212 can rotate relative to the gear case 228. Therefore, the number of rotations allowed by the engagement force of the Cs clutch 232 is determined.

  Thus, by controlling the allowable number of rotations of the stator 212 by the engagement force of the Cs clutch 232, the torque capacity of the torque converter 204 can be made variable. For example, when the Cs clutch 232 is engaged and the stator 212 is fixed to the gear case 228 (that is, the rotation speed is zero), the torque converter 204 is connected to the input shaft 218 of the torque converter 204 and the torque converter. The torque capacity is such that no differential rotation occurs with the output shaft 222 of 204.

  With such a configuration, by reducing the engagement force of the Cs clutch 232 and allowing the stator 212 to rotate, the torque capacity of the torque converter 204 is reduced by losing the reaction force in the stator 212. Thus, the same function as the function of the lock-up clutch 216 of the vehicle 10 according to the first embodiment can be exhibited.

  In such a configuration, the upper limit value of the shared torque capacity coefficient by the Cs clutch 232 is calculated, and the engagement force of the Cs clutch 232 is changed so that the shared torque capacity coefficient by the Cs clutch 232 changes along the calculated upper limit value. By controlling the above, the same effect as that produced by the vehicle control apparatus according to the first embodiment can be exhibited.

  In the vehicle control device according to the present embodiment, the control target of the vehicle control device according to the first embodiment is the lock-up clutch 216, and the hydraulic pressure command value of the lock-up clutch 216 is a control amount. On the other hand, the Cs clutch 232 is controlled, and the hydraulic pressure command value of the Cs clutch 232 is used as a control amount. Other operations of ECU 300 are the same as the operations of ECU 300 that is the vehicle control device according to the first embodiment. Therefore, detailed description thereof will not be repeated.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  DESCRIPTION OF SYMBOLS 10 Vehicle, 100 Engine, 102 Intake passage, 104 Air cleaner, 106 Air flow meter, 108 Throttle valve, 110 Throttle motor, 112 Throttle opening sensor, 200 Automatic transmission, 202 Transmission mechanism, 204 Torque converter, 206 Hydraulic circuit, 210 Pump Impeller, 212 Stator, 214 Turbine runner, 216 Lock-up clutch, 218 Input shaft, 220 One-way clutch, 222, 230 Output shaft, 224 Outer race, 226 Inner race, 228 Gear case, 240 First set, 242, 252 Sun gear, 244 , 254 Pinion gear, 246, 256 Ring gear, 248, 258 Carrier, 250 Second set, 260 B1 brake, 262 B2 brake H.264 C1 clutch, 266 C2 clutch, 300 ECU, 302 accelerator position sensor, 304 stop lamp switch, 306 memory, 308 wheel speed sensor, 310 position switch, 312 shift lever, 314 engine speed sensor, 316 input shaft speed sensor 318, output shaft rotation speed sensor, 352 start determination unit, 354 N control execution determination unit, 356 engagement determination unit, 358 correction amount calculation unit, 360 return control unit, 362 upper limit guard control execution unit, 364 end determination unit, 366 Normal control execution unit, 400 wheels, 402 differential gear, 404 drive shaft, 406 propeller shaft.

Claims (6)

A vehicle control device for a vehicle on which an automatic transmission including a torque converter and a transmission mechanism and an engine are mounted, wherein the transmission mechanism has a first clutch to be engaged when the vehicle starts. The torque converter has a second clutch for changing the torque capacity of the torque converter,
The vehicle control device includes:
A neutral control unit for executing neutral control for controlling the engaging force of the first clutch so that the engaged first clutch is disengaged when the first execution condition is satisfied;
A return control unit for executing a return control for controlling an engagement force of the first clutch so that the non-engaged first clutch returns to the engaged state when a return condition is satisfied;
A variable capacity control unit for executing variable capacity control for controlling the engagement force of the second clutch so that the torque capacity matches the torque capacity corresponding to the state of the vehicle when the second execution condition is satisfied; ,
When the return condition and the second execution condition are satisfied at the same time, the lower limit value of the engine speed for avoiding the engine stall and the current value of the engine until the return control by the return control unit ends. An upper limit guard that calculates the upper limit value of the torque capacity of the second clutch based on the torque and controls the engagement force of the second clutch so that the torque capacity of the second clutch changes along the upper limit value. A vehicle control device including a control unit.   The vehicle variable control device according to claim 1, wherein the variable capacity control unit executes the variable capacity control after the return control is completed. The capacity variable control unit calculates a correction amount for a control amount for the second clutch when the capacity variable control is being executed,
The vehicle control device according to claim 2, wherein the upper limit guard control unit controls an engagement force of the second clutch using the correction amount.   2. The vehicle control device according to claim 1, wherein the second clutch is a lock-up clutch for bringing the input shaft and the output shaft of the torque converter into a directly connected state. The torque converter includes a pump impeller, a turbine runner, and a stator,
2. The vehicle control device according to claim 1, wherein the second clutch is a clutch for limiting rotation of at least one of the pump impeller, the turbine runner, and the stator. A vehicle control method for a vehicle equipped with an automatic transmission including a torque converter and a transmission mechanism, and an engine, wherein the transmission mechanism has a first clutch for engaging when the vehicle starts. The torque converter has a second clutch for changing the torque capacity of the torque converter,
The vehicle control method includes:
Executing neutral control for controlling the engaging force of the first clutch so that the engaged first clutch is disengaged when the first execution condition is satisfied;
Executing a return control for controlling an engagement force of the first clutch so that the non-engaged first clutch returns to the engaged state when a return condition is satisfied;
Executing a variable capacity control for controlling the engaging force of the second clutch so that the torque capacity matches the torque capacity corresponding to the state of the vehicle when the second execution condition is satisfied;
When the return condition and the second execution condition are satisfied at the same time, based on the lower limit value of the engine speed for avoiding the engine stall and the current torque of the engine until the return control is finished. Calculating the upper limit value of the torque capacity of the second clutch, and controlling the engagement force of the second clutch so that the torque capacity of the second clutch changes along the upper limit value. Control method.

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