JP2010084609A - Vehicle control device and control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means inhibiting a sudden rise of engine torque or engine speed according to the gradient of a road surface in restarting the engine from an idling stop state. <P>SOLUTION: An automobile W is equipped with an engine 1, a torque converter 20 including a lock-up clutch 26, and an automatic transmission 10. The engine 1 is stopped with a control unit if an engine stop condition is satisfied, and the engine 1 is restarted if an engine restart condition is satisfied, when the automatic transmission 10 is in a D-range while the automobile W stops. The sudden rise of engine speed in engine restart is inhibited through the slip engagement of a lock-up clutch 26 and rolling vibration of the engine 1 is inhibited when the engine restart condition is satisfied. The rise rate of the engine torque or engine speed in engine restart is desirably controlled according to the gradient of the road surface. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a vehicle control apparatus and control method for automatically stopping an engine when an engine stop condition is satisfied when the vehicle is stopped, and then automatically restarting the engine when an engine restart condition is satisfied. It is.

  In general, when the automobile is temporarily stopped, the engine rotates in an idling state. However, such idling reduces the fuel efficiency of the automobile and increases the emission of carbon dioxide, which contributes to global warming. Therefore, when the engine stop condition is satisfied when the vehicle is temporarily stopped or idling, the engine is automatically stopped, and when the engine restart condition is satisfied thereafter, the engine is automatically restarted (hereinafter referred to as “idle”). Various engines that perform “stop” are proposed (for example, see Patent Document 1).

By the way, when restarting the engine that performs idle stop in this way, at the start of the engine rotation, the engine torque or the engine speed rapidly increases, and the reaction force of the engine torque that rapidly increases in this way causes rolling vibration in the engine, There is a problem that the driver feels strange. Therefore, for example, in the engine disclosed in Patent Document 1, when the engine is restarted from the idle stop state, the motor generator is regeneratively controlled to suppress the rotation of the engine output shaft and prevent the engine speed from rapidly increasing. Yes.
JP-A-9-71138 (paragraph [0024], FIG. 1)

  However, there is a problem that the technique for suppressing the engine torque or the engine speed at the time of restart from the idle stop state disclosed in Patent Document 1 cannot be used for an ordinary automobile not provided with a motor generator. There is also a problem that a large motor generator is required to effectively prevent a sudden increase in engine speed at the time of restart.

  Further, when the vehicle is started by restarting the engine from the idle stop state, an appropriate increase rate of the engine torque or the engine speed varies depending on the road surface condition, for example, the road surface gradient. However, the conventional idle stop control disclosed in Patent Document 1 does not take into account any road surface conditions, and thus there is a problem that the engine restart or the vehicle start may not be performed smoothly. .

  The present invention has been made to solve the above-described conventional problems, and effectively suppresses or prevents a sudden increase in engine speed or engine torque when the engine is restarted from an idle stop state in an idle stop engine. It is possible to effectively suppress or prevent the occurrence of rolling vibrations in the engine, and further to restart the engine or start the vehicle appropriately according to the road surface condition, particularly the road surface gradient. Providing means is a problem to be solved.

  In order to solve the above problems, the vehicle control device according to the present invention is such that the automatic transmission can transmit power when the vehicle equipped with the engine, the fluid transmission device, and the automatic transmission is stopped. When the predetermined engine stop condition is satisfied, the engine is stopped while the engine is restarted when the predetermined engine restart condition is satisfied. The vehicle control device includes engine speed increase rate changing means for changing an engine speed increase rate at the time of engine speed increase (at the time of startup) when restarting the engine, and a road surface on which the vehicle is stopped. Climbing judgment means for judging whether or not the road is an uphill road. Here, the engine speed increase rate changing means increases the engine speed increase rate at the time of restarting the engine when the road surface where the vehicle is stopped is an uphill road compared with a non-uphill road. .

  The vehicle control device according to the present invention preferably includes a brake operation detecting means for detecting a brake operation. In this case, when the engine speed is restarted by releasing the brake operation (depressing the brake pedal) (only), the engine speed increase rate changing means changes the engine speed according to whether or not the road surface is an uphill road. It is preferable to change the number increase rate.

  The vehicle control device according to the present invention preferably includes a gradient detecting means for detecting the gradient of the road surface on which the vehicle is stopped. In this case, the engine speed increase rate changing means preferably increases the engine speed increase rate when the engine is restarted as the road surface gradient increases.

  In the vehicle control device according to the present invention, when the fluid transmission device has a lock-up clutch, the engine speed increase rate changing means slips the lock-up clutch to restart the engine. It is preferable to change the engine speed increase rate at the time.

  In the vehicle control method according to the present invention, when the vehicle equipped with the engine, the fluid transmission device, and the automatic transmission is stopped, the automatic transmission is in a state where power can be transmitted. The engine is stopped if the engine stop condition is satisfied, and the engine is restarted if a predetermined engine restart condition is satisfied. In this vehicle control method, the engine speed increase rate at the time of engine speed increase (at the time of start-up) when the engine is restarted is changed, and the road surface on which the vehicle is stopped It is determined whether or not the road is a road, and when the road surface is an uphill road, the rate of increase in the engine speed when the engine is restarted is larger than when the road surface is a non-uphill road.

  According to the vehicle control device or the control method of the present invention, it is possible to preferably change the engine speed increase rate when the engine speed increases when the engine is restarted. It is possible to reduce the rate of increase in engine rotation at the time of starting. Therefore, when the engine is restarted from the idle stop state, it is possible to effectively suppress or prevent the occurrence of rolling vibration in the engine due to the reaction force of the engine torque.

  In addition, when the road surface where the vehicle is stopped is an uphill road, the rate of increase in the engine speed when restarting the engine is increased compared to when the road is not uphill road, so the vehicle can move backward on the uphill road, etc. It is possible to effectively prevent the occurrence of defects.

  Hereinafter, embodiments of the present invention (best mode for carrying out the present invention) will be described in detail with reference to the accompanying drawings. First, an outline of a power transmission mechanism for an automobile according to the present invention will be described with reference to FIG.

  As shown in FIG. 1, an automobile W (vehicle) includes an engine 1, a torque converter 20 (fluid transmission device) having a lock-up clutch 26, and a multi-speed automatic transmission 10. In this automobile W, the output torque of the engine 1 is input to the torque converter 20 via the engine output shaft 2 (crankshaft). The output torque of the torque converter 20 is input to the automatic transmission 10 via the turbine shaft 27. The output torque of the automatic transmission 10 is transmitted to the left and right axles 62 and 63 via the intermediate transmission mechanisms 14 to 16 and the differential case 64 of the differential device 60.

  In this automobile W, as will be described in detail later, when the automatic transmission 10 is in a state where power can be transmitted when the automobile W is stopped, the engine 1 is stopped if the engine stop condition is satisfied, If the engine restart condition is satisfied, the engine 1 is restarted for idle stop. When the engine 1 is restarted, the increase rate of the engine rotation is suppressed by slip-engaging the lock-up clutch 26 when the engine rotation increases (rises).

  The automatic transmission 10 switches the first planetary gear mechanism 30 and the second planetary gear mechanism 40 to which the output torque of the torque converter 20 is input, and the power transmission path in the planetary gear mechanisms 30 and 40, respectively. A plurality of friction elements 51 to 55 (clutch, brake, etc.) and a one-way clutch 56 are provided. In the following, for convenience, the engine side (right side in FIG. 1) in the direction in which the engine output shaft 2 or the central axis of the turbine shaft 27 extends is referred to as “right”, and the opposite side is referred to as “left”.

  Thus, in the automatic transmission 10, by switching the power transmission path in the first planetary gear mechanism 30 and the second planetary gear mechanism 40, the 1st to 4th speeds of the D range and the 1st to 3rd speeds of the S range are changed. , L range 1-2 speed and R range reverse speed can be set. An oil pump 12 that is driven by the engine output shaft 2 via a converter case 21 is disposed on the left side of the torque converter 20.

  The first planetary gear mechanism 30 includes a sun gear 31, a plurality of pinions 32 that mesh with the sun gear 31, a pinion carrier 33 that supports the pinion 32, and a ring gear 34 that meshes with the pinion 32. On the other hand, the second planetary gear mechanism 40 is provided with a sun gear 41, a plurality of pinions 42 that mesh with the sun gear 41, a pinion carrier 43 that supports the pinion 42, and a ring gear 44 that meshes with the pinion 42.

  A forward clutch 51 is interposed between the turbine shaft 27 that is the torque output shaft of the torque converter 20 and the sun gear 31 of the first planetary gear mechanism 30 (with respect to the power transmission path). A river clutch 52 is interposed between the turbine shaft 27 and the sun gear 41 of the second planetary gear mechanism 40. A 3-4 clutch 53 is interposed between the turbine shaft 27 and the pinion carrier 43 of the second planetary gear mechanism 40. Further, a 2-4 brake 54 that can fix the sun gear 41 of the second planetary gear mechanism 40 is provided.

  The ring gear 34 of the first planetary gear mechanism 30 and the pinion carrier 43 of the second planetary gear mechanism 40 are fixedly connected, and a low reverse brake 55 and a one-way clutch 56 are in parallel between these and the transmission case 11. It is arranged. The pinion carrier 33 of the first planetary gear mechanism 30 and the ring gear 44 of the second planetary gear mechanism 40 are fixedly connected, and these are connected to the output gear 13. The output gear 13 meshes with the first intermediate gear 14 on the idle shaft 16 that constitutes the intermediate transmission mechanism. Further, the second intermediate gear 15 on the idle shaft 16 meshes with the input gear 61 of the differential device 60. Thus, the torque of the output gear 13 is transmitted to the left and right axles 62 and 63 via the differential case 64 of the differential device 60.

(○)はＬレンジのみで作動
Table 1 shows the relationship between the operating states of the friction elements 51 to 55 and the one-way latch 56 and the gear position.

[Table 1]
Table 1 Relationship between operating state of each friction element and gear position

(○) operates only in the L range

  Hereinafter, a specific structure and function of the torque converter 20 having the lockup clutch 26 will be described with reference to FIGS. 2 and 3. In the following, for the sake of convenience, in the positional relationship in FIG. 2, the engine side (right side in FIG. 2) is referred to as “right” with respect to the direction in which the engine output shaft 2 or the central axis of the turbine shaft 27 extends. Is called “left”.

  As shown in FIGS. 2 and 3, the torque converter 20 includes a pump 22 fixed to a converter case 21 connected to the engine output shaft 2, and a pump 22 disposed facing the pump 22 via hydraulic oil. Between the converter case 21 and the turbine 23, the stator 23 that is supported by the transmission case 11 via the one-way clutch 24 between the turbine 23 and the pump 22, and increases the torque. A lockup clutch 26 that directly connects the engine output shaft 2 and the turbine 23 via the converter case 21 is provided. The boss 23 a of the turbine 23 is splined to the turbine shaft 27, whereby the output torque of the turbine 23 is transmitted to the both planetary gear mechanisms 30, 40 via the turbine shaft 27.

  The lock-up clutch 26 has a clutch piston 26 p that is disposed so as to face the flat portion 21 a of the converter case 21. The lockup clutch 26 is fastened to the flat surface portion 21a by the hydraulic pressure supplied into the fastening chamber 26a located on the left side of the piston 26p. At this time, the engine output shaft 2 and the turbine shaft 27 are directly connected. Further, the lock-up clutch 26 is released by the operating hydraulic pressure supplied into the release chamber 26b located on the right side of the piston 26p. The lockup clutch 26 is controlled to a slip state by adjusting the hydraulic pressure supplied to the release chamber 26b. Note that the lock-up clutch 26 may be a decompression type that is fastened by decompressing the inside of the release chamber 26b. Moreover, the pressurization type thing fastened by pressurizing the fastening chamber 26a may be used.

  Supply / discharge of hydraulic oil or hydraulic pressure to / from the lockup clutch 26 of the torque converter 20 is controlled by the hydraulic control circuit 100. The hydraulic control circuit 100 is provided with a duty solenoid valve 123 and a lockup control valve 106 (shift valve) as control means for controlling the slip state of the lockup clutch 26. In addition to the control pressure line 73 for supplying the control pressure adjusted by the duty solenoid valve 123, the lock-up control valve 106 is supplied with a pilot pressure line 74 for supplying pilot pressure and a converter pressure adjusted to a constant pressure. The converter pressure line 75, the fastening pressure line 76 that communicates with the fastening chamber 26a of the lockup clutch 26, and the release pressure line 77 that communicates with the release chamber 26b of the lockup clutch 26 are connected. Note that hydraulic oil or hydraulic pressure is supplied from the main pump 2 or the electric pump 171 to the lockup control valve 106.

  When pilot pressure is supplied from the pilot pressure line 74 to the lockup control valve 106, as shown in FIG. 2, the spool 106a of the lockup control valve 106 resists the urging force of the spring 106b. Located on the left side, the fastening pressure line 76 communicates with the converter pressure line 75, and the release pressure line 77 communicates with the control pressure line 73. In this case, the converter pressure is used as a fastening hydraulic pressure, and the control pressure is used as a releasing hydraulic pressure.

  In this state, when the duty ratio applied to the duty solenoid valve 123 (the ratio of the on time in one on-off cycle) is increased, the control pressure (release hydraulic pressure) PLU is decreased. As a result, the engaging force of the lockup clutch 26 gradually increases, and finally the lockup clutch 26 is completely engaged, and the torque converter 20 enters a lockup state. On the other hand, as the duty ratio is decreased, the control pressure PLU increases. As a result, the fastening force of the lockup clutch 26 gradually decreases, eventually the lockup clutch 26 is completely released, and the torque converter 20 enters a converter state. Then, by controlling the duty ratio between the lock-up state and the converter state, the control pressure PLU and thus the fastening force of the lock-up clutch 26 are adjusted, the lock-up clutch 26 is half-engaged, and the torque converter 20 slips. It becomes a state.

  The hydraulic control circuit 100 is provided with an oil pump 12 driven by the engine output shaft 2 and an electric pump 171 driven by a pump motor 172 as a supply source of hydraulic oil or hydraulic pressure. The electric pump 171 and the pump motor 172 are assembled to the outer wall of the transmission case 11. Similar to the oil pump 12, the electric pump 171 sucks the hydraulic oil stored in the oil pan 170 and supplies it to the lockup control valve 106 and the like via the introduction oil passage 173 and the check valve 174.

  Although not shown in detail, the hydraulic control circuit 100 includes a first on / off solenoid valve (first SV) 111, a second on / off solenoid valve (second SV) 112, and first to third duty solenoid valves. (First to third DSV) 121 to 123, linear solenoid valve (LSV) 131 and the like, and by switching the operating state of these valves, the shift stage (range) of the automatic transmission 10 is switched (see FIG. 4). ).

  Table 2 shows combinations (solenoid patterns) of operating states for the respective shift speeds of the first, second SVs 111 and 112 and the first to third DSVs 121 to 123. In Table 2, “◯” indicates that the first and second SVs 111 and 112 and the first to third DSVs 121 to 123 are the upstream side (oil pump 12 side or electric pump 171 side) of the oil passage and the downstream side (friction elements 51 to 51). 55) indicates that the oil passage is in communication with the oil passage, and “x” indicates that the upstream oil passage is blocked and the downstream oil passage is drained.

[Table 2]
Table 2 Relation between solenoid valve operating state and gear position

  Hereinafter, the control system of the automobile W will be described. The automobile W is provided with a control unit 200 that performs control of the lockup clutch 26 and shift control of the automatic transmission 10 and performs idle stop control. The control unit 200 is a comprehensive control device for an automobile W or a power plant including a computer or a microcomputer, and includes a central processing unit (CPU) that executes processing such as computation according to a program, RAM, ROM, and the like. And a memory for storing programs and data, and an input / output bus (I / O bus) serving as an input / output path for electric signals to the engine control unit 100.

  As shown in FIG. 4, the control unit 200 includes a vehicle speed detected by the vehicle speed sensor 201, a throttle opening detected by the throttle opening sensor 202, and a shift position (range) detected by the shift position sensor 203. The engine speed (rotation speed) detected by the engine rotation sensor 204, the rotation speed (rotation speed) of the torque converter 20 or the turbine shaft 27 detected by the turbine rotation sensor 205, and the oil temperature sensor 206. Engine oil detected by the water temperature sensor 209, the output signal of the idle switch 207 that is turned on when the accelerator pedal is not depressed, the output signal of the brake switch 208 that is turned on when the brake pedal is depressed 1 cooling water temperature And an output of a booster negative pressure sensor 210 for detecting a brake booster negative pressure introduced into a brake booster (not shown) interposed between a brake pedal (not shown) and a master cylinder (not shown). A signal, an output signal of the brake stroke sensor 211 that detects an operation amount of the brake pedal (a depression amount from a non-depression position), and a slope of the road surface on which the vehicle W is running or stopped detected by the slope sensor 212. Are respectively input as control information.

  Thus, the control unit 200 sets the torque converter 20 in the converter state, the lock-up state, or based on the driving state of the vehicle indicated by the signals input from the sensors or switches 201 to 212 and the preset lock-up map. It is determined which state of the slip state should be set, and a control signal is output to the duty solenoid valve 123 for lockup clutch control so that the determined state is obtained.

  The lock-up map is set according to the driving state of the vehicle W such as the vehicle speed and the throttle opening of the engine 1. In this lockup map, for example, the high load / low vehicle speed region is a converter region in which the converter state is to be realized, and the torque is increased. The low load / high vehicle speed region is a lock-up region in which the lock-up state is to be realized, and fuel efficiency is improved. The low load / low vehicle speed region is a slip region in which a slip state is to be realized, and both improvement in fuel efficiency and absorption of shock are achieved.

  The control unit 200 also controls the first and second SVs 111 and 112 of the hydraulic control circuit 100 based on the driving state of the vehicle indicated by the signals input from the sensors or switches 201 to 212 and a preset shift map. Then, the first to third DSVs 121 to 123 and the LSV 131 are driven to perform the shift control of the automatic transmission 10, and the electric pump 171 or the pump motor 172 at that time is controlled to be driven. Such shift control is well known to those skilled in the art, and since such shift control is not the gist of the present invention, its detailed description is omitted.

  Hereinafter, the control procedure of the idle stop control according to the present invention executed by the control unit 200 will be described. The control unit 200 performs idle stop control by controlling the fuel injection valve 3, the ignition plug 4, the starter motor 5 and the like of the engine 1 based on various input control information. First, the outline of the idle stop control according to the present invention will be described.

  When the automatic transmission 10 is in a state in which power can be transmitted when the automobile W is stopped, the control unit 200 stops the engine 1 if the engine stop condition is satisfied, and if the engine restart condition is satisfied. The engine 1 is restarted. When the engine 1 is restarted, the engine torque increase rate or the engine speed increase rate is controlled by slip-engaging or slip-controlling the lock-up clutch 26 when the engine speed is increasing (at the time of startup).

  Further, the control unit 200 determines whether the engine torque increase rate or the engine speed when the engine 1 is restarted according to whether or not the road surface on which the automobile W is stopped is an uphill road, or according to the road surface gradient. Control the rate of climb. Specifically, when the road surface is an uphill road, the engine torque increase rate or the engine speed increase rate is increased as compared with when the road surface is a non-uphill road, or the engine torque increase rate or the engine speed increases as the road surface gradient increases. Increase the rate of increase. The engine torque increase rate or the engine speed increase rate according to whether the road surface is an uphill road or the gradient of the road surface is controlled when the engine 1 is restarted when the brake switch 208 is turned off. Only to do.

Hereinafter, the control procedure of the idle stop control according to the present invention executed by the control unit 200 will be described with reference to the flowcharts shown in FIGS. 5 and 6.
As shown in FIG. 5, in this idle stop control, first, in step S1, the various control signals are read as control information. Subsequently, in step S2, it is determined whether or not the engine 1 is already in idle stop.

  If it is determined in step S2 that the engine 1 is not idling stop (NO), it is determined in step S3 whether an engine stop condition is satisfied. In this idle stop control, it is determined that the engine stop condition is satisfied when all of the following individual conditions are satisfied. It should be noted that the engine stop condition is merely an example, and it is needless to say that the engine stop condition in the idle stop control according to the present invention is not limited to this. For example, any of the following individual conditions may be deleted, and other individual conditions may be added additionally.

<Engine stop condition>
(1) The automatic transmission 10 is in the D range.
(2) The accelerator opening or the throttle opening is zero.
(3) The brake switch 208 is on.
(4) The vehicle speed is zero.
(5) The battery charge amount (SOC) exceeds the set value.
(6) The compressor of the air conditioner is off.

  If it is determined in step S3 that the engine stop condition is not satisfied (NO), that is, if one of the individual conditions is not satisfied, the idle stop cannot be executed. The step is skipped and the process returns to step S1 (return). On the other hand, if it is determined in step S3 that the engine stop condition is satisfied (YES), that is, if all the individual conditions are satisfied, an idle stop is executed in step S4. That is, fuel injection from the fuel injection valve 3 is stopped, spark discharge by the spark plug 4 is stopped, and the engine 1 is stopped.

  If it is determined in step S2 that the engine 1 is in an idle stop (YES), it is determined in step S5 whether an engine restart condition is satisfied. In this idle stop control, it is determined that the engine restart condition is satisfied when at least one of the following individual conditions is satisfied. This engine restart condition is merely an example, and it is needless to say that the engine restart condition in the idle stop control according to the present invention is not limited to this. For example, one of the following individual conditions may be deleted, or another individual condition may be selectively added

<Engine restart conditions>
(1) The accelerator opening or the throttle opening is not zero.
(2) The brake switch 208 is off.
(3) The battery charge (SOC) is less than or equal to the set value.
(4) The air conditioner compressor is on.

  If it is determined in step S5 that the engine restart condition is satisfied (YES), in step S6, the fuel injection from the fuel injection valve 3 is restarted, and the spark discharge by the spark plug 4 is restarted to restart the engine 1. In step S7, slip control of the lockup clutch 26 for idle stop control (hereinafter simply referred to as “slip control”) is performed. Here, step S6 and step S7 are executed in parallel. Thereafter, the process returns to step S1 (return). When it is determined in step S5 that the engine restart condition is not satisfied (NO), it is not necessary to restart the engine 1, and the process returns to step S1 (return).

The slip control for idle stop control executed in step S7 is performed according to the control procedure shown in FIG.
As shown in FIG. 6, in this slip control, first, in step S11, various state quantities of the automobile W are detected by various sensors or input signals from the switches 201-212. Subsequently, an actual slip amount SLU is calculated in step S12. The actual slip amount SLU is a value obtained by subtracting the output rotational speed of the lockup clutch 26 (that is, the rotational speed Nt of the turbine shaft 27) from the input rotational speed of the lockup clutch 26 (that is, engine rotational speed Ne).

  Next, in step S13, it is determined whether or not the brake switch 208 is off. If it is determined that the brake switch 208 is off (YES), the target slip amount SLUo is set in step S14 according to the road surface gradient. In this case, the engine 1 is restarted due to the driver removing his foot from the brake pedal. Therefore, basically, the automobile W is in a state where the brake is not applied. Therefore, when the road surface is an uphill road, if the output torque of the engine 1 is small, the automobile W may move backward. Therefore, in order to prevent such a reverse, the target slip is set so that the target value (see FIG. 8) of the engine torque increase rate or the engine speed increase rate when the engine 1 is restarted increases as the road surface gradient increases. Set the quantity SLUo.

  On the other hand, if it is determined in step S13 that the brake switch 208 is on (NO), the target slip amount SLUo is set in step S15 regardless of the road gradient. In this case, since the automobile W is in a braked state, there is no possibility that the automobile W moves backward even if the road surface is an uphill road. Therefore, the target slip amount SLUo is set so that the normal engine torque increase rate or the engine speed increase rate for flat ground is obtained without considering the road gradient.

  After the target slip amount SLUo is set in step S14 or step S15, it is determined in step S16 whether the actual slip amount SLU is larger than the target slip amount SLUo. When it is determined in step S16 that the actual slip amount SLU is larger than the target slip amount SLUo (YES), that is, when the engine torque increase rate or the engine speed when the engine 1 is restarted is higher than the target value (see FIG. 8). In step S17, the control pressure (release hydraulic pressure) PLU is changed (decreased) in the direction in which the lockup clutch 26 is engaged. That is, the resistance (rotation suppression force) acting on the engine output shaft 2 from the lockup clutch 26 is increased so that the engine torque increase rate or the engine speed when the engine 1 is restarted approaches the target value.

  On the other hand, if it is determined in step S16 that the actual slip amount SLU is less than or equal to the target slip amount SLUo (NO), that is, if the engine torque increase rate or engine speed when the engine 1 is restarted is lower than the target value, step In S18, the control pressure (release hydraulic pressure) PLU is changed (increased) in the direction in which the lockup clutch 26 is released. That is, the resistance (rotation suppression force) acting on the engine output shaft 2 from the lockup clutch 26 is reduced so that the engine torque increase rate or the engine speed when the engine 1 is restarted approaches the target value.

  As described above, the slip control for the idle stop control shown in FIG. 6 is basically feedback control in which the actual slip amount SLU follows the target slip amount SLUo in time series. However, this slip control may be performed by feedforward control with a time-series set value set in advance based on experimental data. Moreover, you may perform slip control by the combination control which combined feedback control and feedforward control. It should be noted that the fastening force of the lockup clutch 26 is corrected or learned based on the history of the increase in engine speed at the previous or previous restart of the engine 1, and individual variations in the lockup clutch 26 or the hydraulic control circuit 100 are detected. Or you may make it respond | correspond to a secular change.

  By the way, in this idle stop control, when the engine 1 is restarted, the oil pump 12 driven by the engine drive shaft 2 is engaged with the lock-up clutch 26 until the rotational speed of the engine output shaft 2 increases to some extent. Insufficient hydraulic pressure cannot be supplied. Therefore, in this idle stop control, when the slip control is performed in step S7, the hydraulic pressure is supplied to the lockup clutch 26 by the electric pump 172 driven by the pump motor 172.

  However, the means for supplying the hydraulic oil or hydraulic pressure to the lockup clutch 26 in the slip control is not limited to the electric pump 172, and any means can be used as long as the hydraulic oil or hydraulic pressure can be supplementarily supplied. For example, an accumulator that stores hydraulic oil or hydraulic pressure may be provided in the hydraulic pressure control circuit 100, and hydraulic oil or hydraulic pressure may be supplied from the accumulator to the lockup clutch 26. The accumulator stores hydraulic fluid or hydraulic pressure discharged from the oil pump 12 when the engine 1 is operating, and supplies the stored hydraulic fluid or hydraulic pressure to the lockup clutch 26 and the like when the engine 1 is stopped. Can do. In particular, when the electric pump 171 is not provided in the automobile W, the idle stop control according to the present invention can be performed without any trouble by providing such an accumulator.

  The restart of the engine 1 in step S6 can be performed by energizing the starter motor 5 and cranking the engine 1 (hereinafter, the restart of the engine 1 is referred to as “starter restart”). The engine 1 can be restarted by injecting fuel into the cylinder in the expansion stroke in the stopped state without using the starter motor 5, and igniting and burning the fuel (hereinafter referred to as "this"). The restart of the engine 1 is referred to as “self-restart”.)

  Hereinafter, the execution procedure of the self-restart will be described with reference to FIGS. 7 (a) and 7 (b). That is, when the engine 1 having the first to fourth cylinders 7A to 7D is self-restarted, for example, as shown in FIG. 7 (a), the first cylinder 7A in which the piston is stopped in the middle of the compression stroke is first used. The engine output shaft 2 is slightly reversed by pushing down the piston by performing the combustion of the engine. As a result, as shown in FIG. 7B, the piston of the second cylinder 7B in the expansion stroke is raised, and the air-fuel mixture in the second cylinder 7B is compressed. Then, by igniting and burning the air-fuel mixture in the second cylinder 7B that has been compressed and thus increased in temperature and pressure, a torque in the forward rotation direction is applied to the engine output shaft 2 and the engine 1 is restarted. Let

  As described above, in the idle stop control, either starter restart or self-restart can be used. However, in the case of starter restart, the rotation of the engine 1 tends to be dragged by the driving force of the starter motor 5. . Therefore, when the slip control of the lockup clutch 26 is performed in parallel with the restart of the engine 1, it is somewhat preferable to use the self-restart because the slip control is easier. In addition, according to the driving | running state of the motor vehicle W or the engine 1, you may use starter restart and self-restart properly.

  In this idle stop control, the ignition advance angle may be retarded in accordance with the suppression of the engine rotation rate increase by the slip control, and the load on the lockup clutch 26 may be reduced. However, since the engine rotation is not stable before the slip control, such ignition advance retard is performed after the slip control (for example, 1/3 to 1/2 of the rear side of the slip control period). It is preferred to do so. In particular, when self-restart is used for the idle stop control, if the ignition advance is retarded before the idle stop control, the engine 1 may stall during the restart.

  FIG. 8 shows the engine torque when the brake pedal is not depressed (off) during the idle stop in the idle stop control shown in FIGS. 5 and 6 and the brake switch 208 is turned off and the engine 1 is restarted. Or engine speed (graphs G1-G3), target reduction torque (graph G4), brake pedal on / off state (graph G5), brake hydraulic pressure (graph G6), and slip control on / off (graph) An example of the change characteristics with respect to time is shown for G7). In the example shown in FIG. 8, the brake switch 208 is turned off at time t1, and the engine restart condition is satisfied. Then, the slip control starts at time t1 and ends at time t2. The engine 1 is idling after time t2.

  In FIG. 8, a graph G1 indicates an engine torque (or engine speed) that is predicted to be generated when the engine 1 is simply restarted, that is, an engine torque when slip control is not performed (hereinafter referred to as “predicted torque”). )) Over time. A graph G2 shows a preferable increase characteristic of the engine torque (or engine speed) in the slip control, that is, a target torque. A graph G3 shows a change with time of actual engine torque when slip control is performed by feedback control so as to follow the target torque.

  The gradient α with respect to time of the target torque or the target rotational speed (graph G2), that is, the engine torque increase rate or the engine rotational speed increase rate when the engine 1 is restarted is the gradient of the road surface on which the automobile W is stopped as described above. It is preferably set accordingly.

  The graph G4 shows the difference between the predicted torque and the target torque, that is, the engine torque (target reduction torque) to be removed or reduced from the engine output shaft 2 by slip control. When slip control is performed by feedforward control, the hydraulic pressure supplied to the lockup clutch 26 is controlled based on experimental data or the like so that the engine torque corresponding to the graph G4 can be removed or reduced. Good.

  Thus, according to the idle stop control according to the present invention, the engine speed increase rate when the engine speed increases when the engine 1 is restarted can be preferably changed. The rate of increase can be reduced. Therefore, when the engine 1 is restarted from the idle stop state, it is possible to effectively suppress or prevent the occurrence of rolling vibration in the engine 1 due to the reaction force of the engine torque. In addition, when the road surface on which the vehicle W is stopped is an uphill road, the rate of increase in the engine speed when the engine is restarted is larger than when the road surface is a non-uphill road. It is possible to effectively prevent problems such as the above.

  As described above, in this embodiment, the automobile W includes the torque converter 20 and the multistage automatic transmission 10. However, the present invention is not limited to this type of automobile W. The present invention can also be applied to another fluid electric apparatus having a lock-up clutch, for example, an automobile equipped with a fluid coupling (fluid coupling) instead of the torque converter 20. Further, instead of the multi-stage automatic transmission 10, for example, the present invention can be applied to an automobile having a belt-type or toroidal-type continuously variable transmission (CVT).

  Further, as described above, in this embodiment, the lockup clutch 26 is slip-engaged by slip control by feedback control, feedforward control, or a combination control thereof, and the engine torque or engine at the time of engine restart Suppressing or preventing a rapid increase in rotational speed. However, the method of slip-engaging the lock-up clutch 26 is not limited to such slip control. Any method may be used as long as the lock-up clutch 26 can be slip-engaged.

  For example, for a very short time (or almost instantaneously), the maximum hydraulic pressure is supplied to the engagement chamber 26a of the lock-up clutch 26 to bring the lock-up clutch 26 into the lock-up state, and the engine torque or the engine speed at the time of engine restart. You may make it suppress or prevent the rapid rise of. In this case, since the lock-up time is short, the lock-up clutch 26 slips. In this case, the time for supplying the maximum hydraulic pressure may be changed in accordance with the road surface gradient.

It is a skeleton figure which shows typically the composition of the power transmission mechanism of the car concerning an embodiment of the invention. It is side surface sectional drawing of the torque converter of the motor vehicle shown in FIG. 1, and its control hydraulic circuit. It is a figure which shows the hydraulic control circuit for the torque converter and automatic transmission of a motor vehicle shown in FIG. It is a block diagram which shows the structure of a control unit. It is a flowchart which shows the control procedure of idle stop control. It is a flowchart which shows the control procedure of slip control of a lockup clutch. (A), (b) is a figure which shows the state of an engine in the case of restarting an engine by injecting and supplying a fuel in the cylinder which is in an expansion stroke in a stop state and making it ignite and burn. It is a figure which shows the time-dependent change of the state of the motor vehicle at the time of engine restart in the idle stop control which concerns on this invention.

Explanation of symbols

  W automobile, 1 engine, 2 engine output shaft, 3 fuel injection valve, 4 spark plug, 5 starter motor, 7A-7D 1st to 4th cylinder, 10 automatic transmission, 20 torque converter, 22 pump, 23 turbine, 25 Stator, 26 lock-up clutch, 27 turbine shaft, 30 first planetary gear mechanism, 40 second planetary gear mechanism, 100 hydraulic control circuit, 200 control unit, 212 gradient sensor.

Claims (5)

If the engine is in a state capable of transmitting power when the vehicle equipped with the engine, the fluid transmission device, and the automatic transmission is stopped, the engine is satisfied if a predetermined engine stop condition is satisfied. A vehicle control device that restarts the engine if a predetermined engine restart condition is satisfied,
Engine speed increase rate changing means for changing the engine speed increase rate when the engine speed is increased when restarting the engine;
An uphill judging means for judging whether the road surface on which the vehicle is stopped is an uphill road,
The engine speed increase rate changing means increases the engine speed increase rate when restarting the engine when the road surface is an uphill road compared to a non-uphill road. Control device. Brake operation detecting means for detecting the brake operation is provided,
The engine speed increase rate changing means changes the engine speed increase rate according to whether or not the road surface is an uphill road when the engine is restarted by releasing the brake operation. The vehicle control device according to claim 1, wherein: A slope detecting means for detecting the slope of the road surface;
The vehicle control device according to claim 1 or 2, wherein the engine speed increase rate changing means increases the engine speed increase rate when the engine is restarted as the gradient increases. The fluid transmission device has a lock-up clutch,
The engine speed increase rate changing means changes the engine speed increase rate when the engine is restarted by slip-engaging the lockup clutch. The control apparatus of the vehicle as described in one. If the engine is in a state capable of transmitting power when the vehicle equipped with the engine, the fluid transmission device, and the automatic transmission is stopped, the engine is satisfied if a predetermined engine stop condition is satisfied. Is a vehicle control method for restarting the engine if a predetermined engine restart condition is satisfied,
After changing the engine speed increase rate when the engine speed increases when restarting the engine,
Determine whether the road surface on which the vehicle is stopped is an uphill road,
A vehicle control method characterized by increasing an engine speed increase rate when restarting the engine when the road surface is an uphill road compared to when the road surface is a non-uphill road.

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