JP2010084658A - Control method for vehicle equipped with compression self-ignition engine, and control device for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve restarting performance by suppressing a drop in temperature in a cylinder caused by scavenging during an automatic stop, in a diesel engine DE for a vehicle performing the idle stop. <P>SOLUTION: This control method for a vehicle equipped with a compression self-ignition engine includes: a step (step S4) of increasing the rotational resistance of the engine DE by fastening the lock-up clutch 56 of the torque convertor 50 of an automatic transmission AT when the engine DE is automatically stopped; a step (step S6) of stopping fuel supply to the engine DE; and a step (step S7) of regulating the magnitude of the rotational resistance of the engine DE by slip control over a forward clutch 63. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to control of a vehicle equipped with a compression self-ignition engine such as a diesel engine, and in particular, the engine is automatically stopped when a predetermined condition is satisfied, and then restarted. Related.

  Conventionally, for the purpose of reducing fuel consumption, suppressing CO2 emission, and the like, for example, it is known to automatically stop the engine if a predetermined condition is satisfied during a temporary stop of the vehicle (so-called idle stop). In the case of restarting the engine after it has been automatically stopped, it is required to start more reliably and quickly than the normal start corresponding to the ignition operation of the occupant.

  In this regard, a diesel engine that self-ignites fuel by compression of a cylinder is provided with a glow plug for warming the inside of the cylinder and improving fuel ignitability when it is cold. Then, the engine startability is improved by heating the inside of the cylinder by the glow plug at the time of restart.

In addition, the idle stop control device described in Patent Document 2 is an engine equipped with a start acceleration device such as a glow plug or an intake air heating device. Regardless, idle stop control is prohibited.
JP 2004-176469 A JP 2007-023825 A

  However, in the method of heating with a glow plug or the like at the time of restarting the engine as in the conventional example, since the power consumption is considerably large, the battery power temporarily decreases, and other than the glow plug and the like are excluded. There is a problem that the power supplied to the electric load is reduced, and in the case of a glow plug, there is a possibility that the durability reliability thereof is impaired.

  In this regard, the present invention pays attention to the fact that the scavenging of the cylinder is performed while the engine is rotating several times by inertia after the fuel cut, and the temperature is reduced. The startability is improved.

  In order to achieve the above object, in the present invention, after stopping the fuel supply to the cylinder when the engine is automatically stopped, the engine is made possible by increasing the rotational resistance by engaging the direct coupling clutch of the automatic transmission. We try to stop it as quickly as possible.

  Specifically, the invention of claim 1 stops the fuel supply to the cylinder in response to the establishment of the predetermined automatic stop condition and stops the engine, and then supplies the fuel if the predetermined restart condition is satisfied. The object is a vehicle control method that restarts and restarts the engine.

  When the engine self-ignites the fuel by compression of the cylinder and the automatic transmission connected to the engine is provided with a fluid transmission device with a direct coupling clutch, the automatic stop is performed. The engine is stopped in a state in which the direct clutch is engaged after the condition is satisfied.

  When the engine is stopped according to the establishment of the automatic stop condition by the above method, the fuel supply to the cylinder is stopped and the direct connection clutch of the fluid transmission device of the automatic transmission is engaged to increase the rotational resistance of the engine. Thus, after the fuel supply is stopped, the number of inertial rotations of the engine is reduced, and the number of scavenging of the cylinder is reduced. As a result, the cooling of the cylinder by the fresh air that is sucked in is suppressed, and the in-cylinder temperature when the restart condition is subsequently satisfied becomes relatively high, and the engine startability is improved.

  Thus, the direct coupling clutch of the transmission is engaged when the vehicle traveling speed is below a predetermined very low speed, that is, when it is almost stopped in order to prevent an excessive load on the clutch. (Claim 2). The direct coupling clutch is generally released to suppress vibration of the vehicle body due to fluctuations in engine rotation when the traveling speed of the vehicle reaches a predetermined speed. It is fastened again at a low low speed or less (claim 3).

  Preferably, in the automatic transmission, the frictional engagement element that is provided in series with the fluid transmission device and constitutes a predetermined gear stage is controlled to a slip state after the automatic stop condition is satisfied. . That is, since a direct coupling clutch of an automatic transmission generally has a low control response and it is difficult to control a delicate fastening force, this is complemented by, for example, slip control of a forward clutch.

  Specifically, for example, after the automatic stop condition is satisfied, before the fuel supply to the cylinder is stopped, the engagement operation of the direct clutch is started, and the friction engagement element is controlled to the slip state before the engagement operation is completed. (Claim 5) Thus, after the fuel supply is stopped, the rotational resistance of the engine can be increased quickly.

  In addition, after the engagement operation of the direct clutch is completed, the rotational resistance of the engine can be gradually increased by controlling the frictional engagement element having a relatively high controllability to a slip state, resulting in an excessive shock. (Claim 6).

  More preferably, at least in the first half of the process of stopping the engine due to the stop of fuel supply to the cylinder, the flow of intake air to the cylinder is throttled by an intake amount adjusting means such as a throttle valve or a variable valve lift mechanism ( According to the seventh aspect of the present invention, it is possible to more effectively suppress the cooling of the cylinder due to the fresh air, and to reduce the vibration accompanying the compression and expansion of the cylinder during the engine stop process.

  From another viewpoint, the present invention stops the fuel supply to the cylinder and stops the engine in response to the establishment of a predetermined automatic stop condition, and then resumes the fuel supply if a predetermined restart condition is satisfied. A vehicle control device having engine control means for restarting the engine, wherein the engine self-ignites fuel by compression of the cylinder, and an automatic transmission connected to the engine includes: The case where a fluid transmission device with a direct coupling clutch is provided is intended.

  And a transmission control unit configured to engage the direct clutch after the automatic stop condition is satisfied, and the engine control unit supplies fuel to the cylinder in the engaged state of the direct clutch after the automatic stop condition is satisfied. Is stopped (claim 8).

  According to the control device having such a configuration, the control method according to the first aspect of the invention can be easily executed, and the operation of the invention can be obtained easily and reliably.

  Further, the transmission control means releases the direct clutch when the traveling speed decreases while the vehicle is traveling and reaches a predetermined vehicle speed, and then the traveling speed of the vehicle becomes a predetermined very low speed or less. When the automatic stop condition is satisfied, it is preferable that the direct coupling clutch is engaged (Claim 9), and the operation of the inventions according to Claims 2 and 3 described above can be obtained.

  Further, generally, an automatic transmission is provided with a friction engagement element for forming a predetermined gear stage in series with the fluid transmission device, so that the transmission control means establishes an automatic engine stop condition. It is preferable to control the frictional engagement element in a slip state later (claim 10), whereby the action of the invention according to claim 4 described above can be obtained.

  As described above, according to the vehicle control method and the like according to the present invention, a compression self-ignition engine such as a diesel engine is mounted, the engine is automatically stopped when a predetermined condition is satisfied, and then restarted. When the automatic stop is performed, a direct coupling clutch of the automatic transmission is engaged, and the rotational resistance of the engine is increased to reduce the number of inertial rotations after the fuel supply to the cylinder is stopped. The number of scavenging operations can be reduced. As a result, the cooling of the cylinder is suppressed, the temperature in the cylinder at the subsequent restart becomes relatively high, and the startability of the engine is improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that the following description of the preferred embodiment is merely illustrative in nature, and is not intended to limit the present invention, its application, or its use.

(Schematic configuration of powertrain)
FIG. 1 shows a schematic configuration of a diesel engine DE (hereinafter simply referred to as an engine DE) mounted on a vehicle according to an embodiment of the present invention. In the illustrated example, the engine DE is an in-line four-cylinder engine, and the cylinder head 11 and the cylinder block 12 are formed with four cylinders 14, 14,. Although only one cylinder 14 is shown in the figure, when distinguishing four cylinders, they are designated as 14A, 14B, 14C, 14D in order from the first cylinder on the engine front side.

  In each cylinder 14, a piston 16 connected to a crankshaft 15 by a connecting rod (not shown) is fitted and moved up and down as the crankshaft 15 rotates. In the cylinder engine, each of the cylinders 14A to 14D performs a combustion cycle including intake, compression, expansion, and exhaust strokes with a phase difference of 180 ° in crank angle. For example, the combustion cycle is performed in the order of the first cylinder 14A, the third cylinder 14C, the fourth cylinder 14D, and the second cylinder 14B.

  A cavity 16 a that defines a combustion chamber 17 is formed on the upper surface of the piston 16, and a glow plug 18 is disposed in the cylinder head 11 with the tip facing the combustion chamber 17. The cylinder head 11 is provided with a fuel injection valve 19 for each cylinder 14. The fuel injection valve 19 is connected to a common rail 20 that stores fuel in a high-pressure state via a branch pipe 21 for each cylinder 14, and high-pressure fuel supplied from the common rail 20 is directly fed into each cylinder 14. , Is supposed to spray.

  In this embodiment, a fuel pressure sensor SW1 for detecting the fuel pressure is provided in the common rail 20, and the fuel injection amount of the fuel injection valve 19 is controlled by the energization time. A common rail 20 that supplies fuel to the fuel injection valve 19 is connected to a fuel supply pump 23 via a high-pressure fuel supply pipe 22.

  In addition, the cylinder head 11 is provided with an intake port 24 and an exhaust port 25 that open toward the combustion chamber 17 for each cylinder 14, and these ports 24, 25 have openings at the openings to the combustion chamber 17. An intake valve 26 and an exhaust valve 27 are provided. The valve operating systems that drive the intake and exhaust valves 26 and 27 are each provided with known phase variable mechanisms 26A and 27A that can change the rotational phase of the camshaft relative to the crankshaft 15 within a predetermined angle range. .

  An intake passage 28 and an exhaust passage 30 are connected to the intake port 24 and the exhaust port 25, respectively. The downstream portion of the intake passage 28 is a branched intake passage 28a branched for each cylinder 14, and the upstream end of each branched intake passage 28a communicates with the surge tank 28b. An upstream side of the surge tank 28b is a common intake passage 28c, in which an electromagnetic throttle valve 29 (intake amount adjusting means) for restricting the flow of intake air is provided. Although schematically shown in the figure, the common intake passage 28c is provided with an air flow sensor SW2 for detecting the intake flow rate, an intake pressure sensor SW3 for detecting the intake pressure, and an intake temperature sensor SW4 for detecting the intake temperature. It has been.

  On the other hand, the upstream portion of the exhaust passage 30 is also a branched exhaust passage branched for each cylinder 14, and although not shown, exhaust gas is placed downstream of the exhaust manifold where the branched exhaust passages gather. A catalyst for purification, a particulate filter (DPF), and the like are provided.

  Further, an alternator 32 connected to the crankshaft 15 by a timing belt or the like is attached to the engine DE. This alternator 32 has a built-in regulator circuit 33 that adjusts the amount of power generated by controlling the current of a field coil (not shown) and adjusting the output voltage, depending on the electric load of the vehicle, the remaining capacity of the in-vehicle battery, etc. Appropriate power generation operation.

  Further, the engine DE is provided with a starter motor 34 for starting it. The starter motor 34 has a motor body 34a and a pinion gear 34b. The pinion gear 34b reciprocates on the output shaft of the motor body 34a in a state where relative rotation is impossible. The crankshaft 15 is provided with a concentric ring gear 35 fixed to a flywheel (not shown). When the engine DE is restarted using the starter motor 34, the pinion gear 34b. Is moved to a predetermined meshing position and meshed with the ring gear 35, whereby the crankshaft 15 is rotationally driven.

  Further, the engine DE is provided with two crank angle sensors SW5 and SW6 for detecting the rotation angle of the crankshaft 15, and the engine speed is determined based on a detection signal (pulse signal) output from one crank angle sensor SW5. Is detected, and the crank angle position is detected based on the detection signals out of phase output from the crank angle sensors SW5 and SW6. Further, as shown in the figure, a water temperature sensor SW7 for detecting the coolant temperature of the engine DE (engine water temperature), an accelerator opening sensor SW8 for detecting an accelerator opening corresponding to the operation amount of the accelerator pedal 36 of the vehicle, A brake pedal sensor SW9 for detecting the operation of the brake pedal 37 is provided.

  In addition, an exhaust gas recirculation device 40 is provided in the illustrated engine DE. The exhaust gas recirculation device 40 is branched and connected in the vicinity of a collection portion of the exhaust manifold, and an exhaust gas recirculation (EGR) passage 41 that circulates a part of the exhaust gas from the exhaust passage 30 to the intake passage 28, and the EGR passage 41 And an EGR valve 42 that is provided in the middle and restricts the flow of the exhaust gas to be recirculated.

-Automatic transmission-
Next, with reference to FIG. 2, the overall configuration of the automatic transmission AT mounted on the vehicle according to this embodiment is shown. The automatic transmission AT includes, as main components, a torque converter 50 with a lock-up mechanism, and a transmission gear mechanism 60 that changes the output of the torque converter 50 and transmits it to the wheel side. The transmission gear mechanism 60 includes first and second sets of planetary gear mechanisms 61 and 62 in the illustrated example, and three sets of wet multiple gears as frictional engagement elements that selectively restrict the rotation of the rotating elements. The plate clutches 63 to 65, two sets of wet multi-plate brakes 66 and 67, and one set of one-way clutch 68 are provided.

  The torque converter 50 is disposed opposite to the pump 52 fixed in a case 51 connected to the crankshaft 15 of the engine DE, and is disposed through the hydraulic oil (ATF) by the pump 52. A turbine 53 to be driven, a stator 55 interposed between the pump 52 and the turbine 53 and supported by a transmission casing 70 via a one-way clutch 54 to increase torque; the case 51 and the turbine And a lockup clutch 56 (direct coupling clutch) that directly connects the engine output shaft 1 and the turbine 53 via the case 51. The rotation of the turbine 53 is output to a turbine shaft integral with the input shaft 69 of the transmission gear mechanism 60.

  A partition wall 70a is provided on the non-engine side of the torque converter 50, that is, between the torque converter 50 and the transmission gear mechanism 60 so as to partition them in the transmission casing 70, and the partition wall 70a has a machine wall. An oil pump 57 of the type is provided. The oil pump 57 is connected to the case 51 of the torque converter 50, and is driven by the crankshaft 15 of the engine DE through the oil pump 57. Although not shown, an electric oil pump is assembled to the outer wall of the transmission casing 70 separately from the mechanical oil pump 57.

  The first and second planetary gear mechanisms 61 and 62 of the transmission gear mechanism 60 include sun gears 61a and 62a, a plurality of pinions 61b and 62b engaged with the sun gears 61a and 62a, and the pinions 61b and 62b, respectively. And a so-called single planetary gear set having internal gears 61d and 62d engaged with the pinions 61b and 62b.

  A forward clutch 63 is provided between the input shaft 69 and the sun gear 61a of the first planetary gear mechanism 61. A reverse clutch 64 is provided between the input shaft 69 and the sun gear 62a of the second planetary gear mechanism 62. A 3-4 clutch 65 is interposed between the input shaft 69 and the pinion carrier 62c of the second planetary gear mechanism 62, and between the sun gear 62a of the second planetary gear mechanism 62 and the transmission casing 70. A 2-4 brake 66 for fixing the sun gear 62a is arranged.

  Further, an internal gear 61 d of the first planetary gear mechanism 61 and a pinion carrier 62 c of the second planetary gear mechanism 62 are connected, and a low reverse brake 67 and a one-way clutch 68 are connected between these and the transmission casing 70. Are arranged in parallel, and a pinion carrier 61c of the first planetary gear mechanism 61 and an internal gear 62d of the second planetary gear mechanism 62 are connected to each other, and a counter drive gear 71 is connected thereto.

  The counter drive gear 71 meshes with a driven gear 73 of a counter shaft 72 arranged in parallel with the input shaft 69, and the rotation of the counter drive gear 71 is transmitted to the counter shaft 72 by the counter driven gear 73. After being decelerated by the meshing of the output gear 74 on 72 and the ring gear 76 of the differential 75, it is transmitted to the left and right axles 77, 77 via the differential 75.

  Then, by selectively operating the clutches and brakes 63 to 67 in the transmission gear mechanism 60 and switching the power transmission path, the 1st to 4th speeds in the D range (forward travel range), and R The reverse speed in the range can be obtained. That is, only schematically shown in FIG. 1, the transmission casing 70 is integrally provided with a hydraulic control system 78 that supplies and discharges hydraulic pressure to and from the clutches and brakes 63 to 67. .

  Specifically, the relationship between the operating states of the clutches, the brakes 63 to 67 and the one-way clutch 68 and the gears is summarized as shown in FIG. In the figure, (◯) indicates a case where a clutch or the like is engaged. The broken line (◯) of the D range first speed indicates that the low reverse brake 67 is engaged only in the manual mode or the hold mode.

  The above-described engine DE and automatic transmission AT are controlled by a powertrain control module 100 (hereinafter PCM) schematically shown only in FIG. The PCM 100 is composed of a microprocessor having a CPU, a memory, a counter timer group, an interface, and a path for connecting these units, and mainly performs various calculations based on signals from the sensors SW1 to SW9. The operation state of the DE is determined, and in response to this, a control signal is output to the fuel injection valve 19, the phase variable mechanisms 26A and 27A of the valve system, the throttle valve 29, the actuator of the EGR valve 42, and the like.

  Further, when the engine DE is started, the PCM 100 outputs a control signal to the fuel injection valve 19 and the starter motor 34 and also outputs a control signal to the glow plug 18 as necessary. That is, when the engine DE is cold started, the glow plug 18 is energized to warm the inside of the cylinder 14, and the piston 16 of the cylinder 14 that is stopped in the compression stroke at the restart after the automatic stop described later is in an appropriate range. The glow plug 18 is energized also when it is on the top dead center side.

  Further, as shown in FIG. 1, the PCM 100 detects a signal from the vehicle speed sensor SW10 that detects the output rotational speed of the automatic transmission AT as the traveling speed (vehicle speed) of the vehicle and the turbine rotational speed of the automatic transmission AT. At least a signal from the turbine rotation speed sensor SW11, a signal from the oil temperature sensor SW12 that detects the temperature of the hydraulic oil, and a signal from the inhibitor switch SW13 that detects the range selected by the occupant, A predetermined calculation is performed in combination with the signals from the sensors SW1 to SW9, and the hydraulic control system 78 of the automatic transmission AT is controlled so as to achieve the target shift stage determined according to the accelerator opening and the vehicle speed. Output a signal.

(Control procedure for automatic stop)
In this embodiment, for the purpose of reducing fuel consumption and CO2 emission, the engine DE is automatically stopped when a predetermined automatic stop condition is satisfied, and then the engine DE is stopped if a predetermined restart condition is satisfied. It is made to restart (so-called idle stop). That is, when the PCM 100 determines that the automatic stop condition of the engine DE is satisfied, the PCM 100 stops the fuel injection by the fuel injection valve 19 (fuel cut) and stops the engine DE.

  Thereafter, if a predetermined restart condition is satisfied, the PCM 100 starts cranking of the engine DE by the starter motor 34 and starts supplying fuel in order from the cylinders 14 that are stopped in the middle of the compression stroke. Restart the engine DE. In such a restart after an automatic stop, it is required to start more reliably and quickly than a normal start corresponding to the ignition operation of the occupant.

  Therefore, in this embodiment, as a characteristic part of the present invention, at the time of the automatic stop, scavenging in each cylinder 14 is performed while the engine DE is rotated several times by inertia after the fuel supply is stopped, and the temperature decreases. Attention is paid to the fact that the lock-up clutch 56 of the automatic transmission AT is engaged in the engine stop process, and the rotational resistance of the engine DE is increased, thereby reducing the number of inertial rotations of the engine DE until the stop and by scavenging. The temperature drop is suppressed.

  Hereinafter, the automatic stop control of the engine DE in the vehicle of this embodiment will be specifically described with reference to FIGS. 4 and 5. FIG. 4 is a flowchart illustrating an example of a specific control procedure, and FIG. 5 is a timing chart illustrating changes in the engine speed Ne in the engine DE stop process.

  First, in step S1 after the start in the flow of FIG. 4, the process waits until a preset automatic engine stop condition is satisfied. For example, when the stepping operation of the brake pedal 37 continues for a predetermined time and the vehicle is substantially stopped at a vehicle speed of a predetermined low speed (for example, 2 to 5 km / h) or less, the automatic engine stop condition is satisfied. It is determined that If the vehicle speed is reduced to a predetermined speed (for example, 10 to 40 km / h) before this determination, the lockup clutch 56 of the automatic transmission AT is released to suppress the vibration of the vehicle body due to the rotational fluctuation of the engine DE. It is like that.

  If the automatic stop condition is satisfied as described above and YES is determined in step S1 (time t0 in FIG. 5), the process proceeds to step S2 to start the releasing operation of the forward clutch 63, and in the subsequent step S3, the forward clutch 63 is started. The process proceeds to step S4 after waiting for the elapse of a predetermined time (approximately 0.2 to 0.3 seconds) required for releasing the. Here, the engaging operation of the lock-up clutch 56 is started (at the same time t1). In step S5, a predetermined time (approximately 0.3 to 0.5 seconds) required for engaging the lock-up clutch 56 is awaited, and then step S6. Then, the fuel supply to each cylinder 14 of the engine DE is stopped (same time t2), and the process proceeds to the engine stop process.

  During the engine stop process, while the engine DE rotates several times due to inertia, the engine speed Ne decreases while repeating up and down as shown in the figure, and after the compression top dead center of the cylinder 14 is exceeded a predetermined number of times, The top dead center cannot be exceeded against the compression reaction force of the cylinder 14, and after a slight reverse rotation, the engine is stopped (at the same time t4). In this embodiment, the engine DE can be stopped in a shorter time than the normal stopping process indicated by the broken line in the figure by engaging the lockup clutch 56 and increasing the rotational resistance of the engine DE as described above.

  However, since the lock-up clutch 56 is not very responsive and it is difficult to control the delicate fastening force, if the engine DE is fastened simultaneously with the fuel cut and the rotational resistance of the engine DE is rapidly increased, the engine speed drops drastically. May cause an excessive shock. Therefore, in this embodiment, the forward clutch 63 is controlled to be in a slip state simultaneously with the completion of engagement of the lockup clutch 56 (time t2) (step S7 in the flow of FIG. 4), thereby appropriately reducing the rotational resistance of the engine DE. Try to increase.

  Although not shown in FIG. 5, the throttle valve 29 of the engine DE is fully closed at the same time as the lock-up clutch 56 is completely engaged and the slip control of the forward clutch 63 is started (time t2). (Step S8). Thereby, in the first half of the engine stop process, the flow of the intake air to each cylinder 14 can be reduced, and the cooling of the cylinder 14 by the fresh air can be more effectively suppressed, and the cylinder 14 is compressed and expanded. Vibration can also be reduced.

  Further, it is determined whether or not the engine water temperature is lower than a predetermined value (80 ° C. in the illustrated example) (step S9). If the engine water temperature is lower than the predetermined value, the process proceeds to step S10 and the EGR valve 42 of the engine DE is opened. The bypass valve of the cooling water that bypasses the valve is opened so that the gas having the highest temperature is returned to the intake side. On the other hand, if the engine water temperature is equal to or higher than a predetermined value, the EGR valve 42 is not controlled.

  If the engine speed Ne that decreases while repeating up-down as described above in the engine stop process becomes equal to or less than the set speed Ne1 (time t3), YES is determined in step S11 of the flow of FIG. 4 and step S12 is performed. Then, the throttle valve 29 is fully opened. Then, the amount of intake air sucked into the predetermined cylinder 14 that performs the intake stroke thereafter increases and the compression reaction force increases, and the compression top dead center of the cylinder 14 cannot be exceeded, and the engine DE is stopped. It reaches.

  That is, in the engine stop process, the stop position of the engine DE can be predicted based on signals from the crank angle sensors SW5 and SW6, and the cylinder 14 that stops in the middle of the compression stroke is specified from this prediction result. The piston 16 in the cylinder 14 can be stopped at a position suitable for restart on the bottom dead center side by increasing the amount of intake air sucked in immediately before the stop.

  As an example, in this embodiment, in the cylinder 14 that stops in the middle of the compression stroke, the piston 16 is stopped in a range on the bottom dead center side from 100 ° CA before the compression top dead center. This is the cylinder in which the cylinder 14 that stops in the compression stroke burns first at the time of restart. In this cylinder 14, the piston 16 is stopped relatively to the bottom dead center side, so that the effective compression ratio of the cylinder is sufficiently increased. This is because the fuel (air mixture) can be surely self-ignited.

  However, if the temperature is relatively high, the effective compression ratio of the cylinder 14 that stops in the compression stroke may be reduced accordingly. Therefore, the stop position of the piston 16 in the cylinder 14 is corrected to the top dead center side by the temperature in the cylinder. You may make it do. In this way, the stroke to the compression top dead center at the start of cranking is shortened, and the starting time can be further shortened.

  In step S13 of the flow of FIG. 4, it is determined whether the engine DE has completely stopped based on signals from the crank angle sensors SW5 and SW6. If the engine DE has completely stopped (YES), the lockup is performed in step S14. The clutch 56 is released, the forward clutch 63 is engaged in step S15, the EGR valve 42 is closed in step S16, and the engine automatic stop control is ended (END).

  If a predetermined restart condition is satisfied after the engine DE is automatically stopped, the air in the cylinder 14 in the compression stroke is compressed by driving the starter motor 34, and the temperature rises to a predetermined timing. The fuel injected in is ignited and burned. Subsequently, combustion is performed in the order of the cylinder 14 stopped in the intake stroke, the cylinder 14 stopped in the exhaust stroke, the cylinder 14 stopped in the expansion stroke, and the engine DE is started.

  Step S4 in the flow of FIG. 4 corresponds to the step of engaging the lock-up clutch 56 of the automatic transmission AT in a state where the vehicle speed is less than or equal to the low speed after the predetermined automatic stop condition is satisfied, and step S6 is the automatic stop. This corresponds to the process of stopping the engine DE by stopping the fuel supply to the cylinders 14A to 14D according to the establishment of the condition. In this example, the fastening operation of the lockup clutch 56 is started before the fuel cut. I have to.

  Step S7 corresponds to a step of slip control of the forward clutch 63 after the automatic stop condition is satisfied. Here, the slip control is performed after the engagement operation of the lockup clutch 56 is completed. Further, step S8 corresponds to a step of closing the throttle valve 29 in at least the first half of the engine stop process after the fuel cut to restrict the flow of intake air to the cylinders 14A to 14D.

  As described above, in this embodiment, the PCM 100 constitutes an engine control unit that automatically stops the engine DE in response to the establishment of the automatic stop condition, and then restarts the engine DE when the restart condition is satisfied. This engine control means closes the throttle valve 29 during the automatic stop so as to restrict the flow of intake air to the cylinders 14A to 14D.

  The PCM 100 also constitutes transmission control means for controlling the automatic transmission AT. The transmission control means releases the lock-up clutch 56 at a predetermined vehicle speed or less during vehicle travel, and then automatically When the stop condition is satisfied and the vehicle speed becomes a very low speed or less, the forward clutch 63 is slip-controlled while being engaged.

  Therefore, according to the vehicle control method and the like according to this embodiment, the diesel engine DE is mounted and automatically stopped in a predetermined situation and then restarted. In the engine stop process at the time of the automatic stop, By fastening the lock-up clutch 56 of the automatic transmission AT and increasing the rotational resistance of the engine DE, as shown in FIG. 5, the number of rotations due to the inertia of the engine DE after the fuel cut is reduced, and the cylinder 14 The number of scavenging operations can be reduced, thereby suppressing a decrease in the in-cylinder temperature and improving the restartability thereafter.

  In addition, first, the fastening operation of the lock-up clutch 56 is started, and the fuel is cut after the time required for the lock-up clutch 56 has elapsed. At the same time, the slip control of the forward clutch 63 is performed. In addition, the rotational resistance of the engine DE can be increased moderately and moderately, and no excessive shock is generated.

  In addition, by reducing the intake air by controlling the throttle valve 29 in the first half of the engine stop process, it is possible to more effectively suppress a decrease in the temperature in the cylinder and to suppress vibration and noise caused by the compression of the cylinder 14.

  In the above-described embodiment, the automatic stop condition is satisfied at a relatively high vehicle speed, and the accelerator pedal is released and the deceleration fuel cut is executed while the vehicle is traveling at a speed higher than the predetermined vehicle speed. When (in this state, the lock-up clutch 56 of the automatic transmission AT is engaged), the automatic stop condition may be satisfied. In this case, the lock-up clutch 56 only needs to be maintained in the engaged state even after the automatic stop condition is satisfied. In this case, the fuel stop period related to the automatic stop of the engine becomes longer, and fuel consumption and CO2 emission can be further reduced.

  Further, the slip control of the forward clutch 63 may be started before the fuel cut (for example, in response to the establishment of the automatic stop condition), thereby increasing the rotational resistance of the engine DE more quickly. be able to.

  Further, instead of the forward clutch 63, for example, the 3-4 clutch 65 may be slip-controlled, and if it is configured by a multi-plate clutch instead of a band brake with poor controllability, the 2-4 brake 66 should also be used. Can do. Of course, the automatic transmission AT is not limited to four forward speeds, and may be 5 to 8 speeds. In that case, the automatic transmission AT is provided in series with the torque converter 50, and preferably constitutes the forward speed stage. Friction fastening elements are available.

  Further, the throttle of the intake air in the first half of the engine stop process is not limited to the throttle valve 29. For example, the variable mechanism capable of continuously changing the lift amount of the intake valve 26 or the operation of the intake valve 26 is temporarily stopped. The intake air may be throttled by a pause mechanism or the like that can be used.

  Furthermore, the present invention is not limited to a diesel engine, but can be applied to various compression self-ignition engines in which fuel is supplied into a cylinder and compressed by a piston ascending to be self-ignited.

  The present invention can improve the restartability of the engine in idle stop or the like, and is suitable for an automobile equipped with a diesel engine, for example.

1 is a schematic configuration diagram of an engine mounted on a vehicle according to the present invention. It is a skeleton figure which shows the structure of the automatic transmission. It is a figure which shows the relationship between the engagement states, such as a clutch of an automatic transmission, and a gear stage. It is a flowchart figure which shows the procedure of the engine automatic stop control. It is a timing chart figure which shows the operating state of a clutch in the engine stop process, and the reduction state of engine speed in association.

Explanation of symbols

DE Diesel engine 14 cylinder 29 Throttle valve (intake air amount adjusting means)
AT automatic transmission 50 Torque converter (fluid transmission)
56 Lock-up clutch (direct coupling clutch)
63 Forward clutch (friction engagement element)
100 PCM (engine control means, transmission control means)

Claims (10)

A vehicle that stops the fuel supply to the cylinder in response to the establishment of a predetermined automatic stop condition and stops the engine, and then restarts the fuel supply and restarts the engine if the predetermined restart condition is satisfied. Control method,
The engine self-ignites the fuel by compression of the cylinder, and the automatic transmission connected to the engine is provided with a fluid transmission device with a direct coupling clutch,
A control method for a vehicle equipped with a compression self-ignition engine, wherein the engine is stopped in a state where the direct coupling clutch is engaged after the automatic stop condition is satisfied.   The vehicle control method according to claim 1, wherein the direct coupling clutch is fastened in a state where the traveling speed of the vehicle is equal to or lower than a predetermined very low speed.   The vehicle control method according to claim 2, wherein the direct coupling clutch is released when the traveling speed decreases during traveling of the vehicle and reaches a predetermined speed higher than a very low speed.   The friction engagement element that is provided in series with the fluid transmission device in the automatic transmission and that constitutes the predetermined shift stage is controlled to a slip state after the automatic stop condition is satisfied. The vehicle control method described.   5. The engagement operation of the direct coupling clutch is started before the fuel supply to the cylinder is stopped after the automatic stop condition is satisfied, and the friction engagement element is controlled to be in a slip state before the engagement operation is completed. Vehicle control method.   The vehicle control method according to claim 4, wherein the frictional engagement element is controlled to be in a slip state after the directing clutch is engaged.   The vehicle control method according to any one of claims 1 to 6, wherein the flow of intake air to the cylinder is narrowed by the intake air amount adjusting means at least in the first half of the process of stopping the engine due to the stop of fuel supply to the cylinder. Engine control that stops the fuel supply to the cylinder in response to the establishment of a predetermined automatic stop condition and then stops the engine, and then restarts the fuel supply and restarts the engine if the predetermined restart condition is satisfied. A vehicle control device comprising means,
The engine self-ignites the fuel by compressing the cylinder,
The automatic transmission connected to the engine is equipped with a fluid transmission device with a direct clutch,
A transmission control means for engaging the direct clutch after the automatic stop condition is satisfied;
A control device for a vehicle equipped with a compression self-ignition engine, wherein the engine control means is configured to stop fuel supply to a cylinder in an engaged state of the direct coupling clutch after the automatic stop condition is satisfied.   The transmission control means releases the direct coupling clutch when the traveling speed decreases while the vehicle is traveling and reaches a predetermined vehicle speed, and then the vehicle traveling speed becomes equal to or less than a predetermined very low speed to automatically stop the vehicle. The vehicle control method device according to claim 8, wherein the direct coupling clutch is engaged when the condition is established. In the automatic transmission, a frictional engagement element for constituting a predetermined shift stage is provided in series with the fluid transmission device,
The vehicle control device according to claim 8 or 9, wherein the transmission control means controls the frictional engagement element to a slip state after an automatic engine stop condition is satisfied.

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