JP4978523B2 - Automatic stop device for diesel engine - Google Patents

Description

  The present invention includes an automatic stop / restart control means for automatically stopping the engine when a predetermined automatic stop condition is satisfied, and restarting the engine after the automatic stop when a predetermined restart condition is satisfied; The present invention belongs to a technical field relating to an automatic stop device for a diesel engine provided with a glow plug disposed facing each cylinder of the engine.

2. Description of the Related Art Conventionally, an engine control system (idle stop system) that automatically stops an engine during idling is known for the purpose of reducing fuel consumption and suppressing CO ₂ emission.

For example, in the case shown in Patent Document 1, when an idle stop system is applied to a diesel engine, in order to prevent deterioration of fuel ignitability due to a decrease in the in-cylinder temperature due to the automatic stop of the engine, The inside of the cylinder is heated by a glow plug.
JP 2004-176469 A

  By the way, in a vehicle equipped with an idle stop system, since engine start / stop is frequently repeated, power is supplied from the battery to the engine starter every time the engine is restarted, and the battery power tends to be insufficient. .

  For this reason, when an idle stop system is applied to a vehicle equipped with a diesel engine as shown in Patent Document 1, the power supplied to the engine starter is insufficient when the engine is restarted, and the cranking power is reduced. As a result, there is a problem that engine restartability deteriorates.

  Therefore, it is conceivable to separately provide a dedicated battery (second battery) for supplying power to the engine starter when the engine is restarted. As a result, sufficient power can be supplied from the dedicated battery to the starter that requires reliable operation when an engine restart request is made, and engine restartability can be improved.

  However, even if the dedicated battery is provided as described above, if the dedicated battery is deteriorated due to, for example, the electrode being dropped, the power supplied from the dedicated battery to the engine starter is reduced when the engine is restarted. There is a problem that gets worse.

  The present invention has been made in view of such points, and an object of the present invention is to provide an automatic stop device for a diesel engine that automatically stops the engine when a predetermined automatic stop condition is satisfied. In addition, the ingenuity in the control method is intended to improve the startability when the engine is restarted.

  To achieve the above object, the present invention includes a first battery for supplying electric power to an electric load of a vehicle including a glow plug, and a second battery for supplying electric power to a starter, When the battery is deteriorated, the starter is driven while operating the glow plug when restarting the engine.

  Specifically, in the first aspect of the invention, the engine is automatically stopped when a predetermined automatic stop condition is satisfied, and the engine after the automatic stop is restarted when the predetermined restart condition is satisfied. An automatic stop device for a diesel engine including a stop / restart control means and a glow plug disposed facing a combustion chamber of each cylinder of the engine is an object.

  A first battery for supplying power to an electric load including at least the glow plug; a second battery for supplying power to the starter of the engine; and a value related to the degree of deterioration of the second battery. A battery deterioration degree detecting means for detecting and outputting the detected information to the automatic stop / restart control means, and the automatic stop / restart control means is based on detection information from the battery deterioration degree detecting means. When it is determined whether or not the deterioration degree of the second battery is greater than a predetermined degree, and the deterioration degree is determined to be equal to or less than the predetermined degree, the glow plug is deactivated when the engine is restarted. When the starter is driven and the deterioration degree of the second battery is determined to be greater than the predetermined degree, the engine is restarted. While operating said glow plug and assumed to be configured so as to drive the starter.

  Thus, by providing a battery for supplying power to the engine starter (second battery) separately from a battery for supplying power to the electric load such as a glow plug (first battery), the automatic stop / When the engine is restarted by the restart control means, sufficient power can be supplied from the second battery to the starter without being affected by the load state of the electric load. The startability can be improved.

  Further, when the automatic stop / restart control means determines that the deterioration degree of the second battery is larger than the predetermined degree based on the detection information from the battery deterioration degree detection means, when restarting the engine, The starter is driven while raising the in-cylinder temperature by operating the glow plug. Therefore, even if the amount of power supplied to the starter is insufficient due to the deterioration of the second battery and the cranking power is reduced, the ignition of the fuel is promoted by the rise of the in-cylinder temperature due to the operation of the glow plug. The restartability of the engine can be improved.

  On the other hand, the automatic stop / restart control means determines that the degree of deterioration of the second battery is not more than a predetermined degree (that is, sufficient cranking power can be obtained by supplying power from the second battery to the starter). ), When restarting the engine, the glow plug is deactivated and the starter is driven. Thereby, it is possible to prevent the glow plug from operating unnecessarily and further deterioration thereof.

  According to a second aspect of the present invention, in the first aspect of the invention, the first battery is configured to be always connected to the electric load including the glow plug so as to be able to supply electric power, and the second battery is a starter of the engine. Is connected between the first battery and the starter, and further includes switching means for switching between a connected state and a disconnected state, and the automatic stop / restart control. When the engine is restarted when the deterioration degree of the second battery is determined to be greater than the predetermined degree, the means causes the first battery and the starter to be connected by the switching means, and The starter is driven by supplying power to the starter from both the first and second batteries, and the starter is started from the start. When the time has elapsed, the switching means switches the first battery and the starter to a non-connected state to cut off the power supply from the first battery to the starter and to supply power from the first battery to the glow plug. Assume that it is configured to start.

  According to this configuration, when the second battery is in a deteriorated state (a state in which the degree of deterioration is greater than the predetermined degree), the automatic stop / restart control means (when the restart condition is When established, the first battery and starter are connected by the switching means, and power is supplied from both the first and second batteries to the starter. Therefore, when the engine is restarted, the shortage of power supplied to the starter due to the deterioration of the second battery can be compensated by the power supplied from the first battery. Ranking power can be obtained, and as a result, engine restartability can be improved.

  The automatic stop / restart control means starts the power supply from the first battery to the glow plug and activates the glow plug when a predetermined time has elapsed since the start of the starter. As a result, the power supply start timing from the first battery to the glow plug can be made different from the start start timing of the starter. For this reason, power supply from the first battery to the glow plug is started at the start of the starter drive. Can be executed simultaneously with the power supply to the starter to prevent the power supplied to other electric loads from being reduced.

  The automatic stop / restart control means cuts off the power supply from the first battery to the starter when the predetermined time has elapsed and the power supply from the first battery to the glow plug is started. Therefore, after the predetermined time has elapsed, power supply to the starter that consumes more power than the glow plug is cut off. For this reason, even if the power supply from the first battery to the glow plug is started as described above, it is possible to sufficiently secure the power supplied to the other electric loads.

  In addition, after the predetermined time has elapsed, the power supply from the first battery to the starter is cut off, so that the power supply from the second battery only to the starter is performed and the cranking power is reduced. Since the in-cylinder temperature rises due to the operation of the glow plug, the restartability of the engine is not impaired.

  In the invention of claim 3, in the invention of claim 1, the automatic stop / restart control means stops when the engine is restarted when the deterioration degree of the second battery is determined to be equal to or less than a predetermined degree. When the piston position of the hour compression stroke cylinder is within a predetermined range, the glow plug is deactivated to drive the starter, while when the piston position of the stop compression stroke cylinder is outside the predetermined range, When the starter is driven while the plug is operated, and when it is determined that the deterioration degree of the second battery is greater than a predetermined degree, the piston position of the compression stroke cylinder at the time of stop is determined when the engine is restarted. Regardless of whether or not it is within the predetermined range, the starter is driven while operating the glow plug. To.

  According to this configuration, when the second battery is in a deteriorated state, the automatic stop / restart control means is configured such that when the engine is restarted, the stop-time compression stroke cylinder (stop of the engine is completed when the automatic stop condition is satisfied). When the second battery is in a non-degraded state while the glow plug is operated, regardless of whether the piston position of the cylinder in the compression stroke is within a predetermined range, the compression stroke cylinder at the time of stop When the piston position is outside the predetermined range, the glow plug is activated to restart the engine. Accordingly, when the cranking force is insufficient because the second battery is in a deteriorated state, and when the compression stroke is insufficient even when the second battery is in a non-deteriorated state, the glow plug is operated to By increasing the temperature, the engine restartability can be improved.

  On the other hand, when the second battery is in a non-degraded state, the automatic stop / restart control means deactivates the glow plug when the piston position of the stop-time compression stroke cylinder is within a predetermined range when the engine is restarted. Restart the engine. Thus, it is possible to prevent the glow plug from being activated and further deteriorated until the second battery is not deteriorated and a sufficient compression stroke can be secured.

  According to a fourth aspect of the present invention, in the third aspect of the invention, further comprising an intake throttle valve disposed in the intake passage of the engine, wherein the automatic stop / restart control means It is assumed that the piston of the compression stroke cylinder at the time of stop is stopped within the predetermined range by controlling the opening of the intake throttle valve.

  According to this configuration, the opening control of the intake throttle valve is executed by the automatic stop / restart control means so that when the engine is automatically stopped, the piston of the stop-time compression stroke cylinder is stopped within a predetermined range. For this reason, when the engine is restarted, it is possible to avoid the operation of the glow plug as much as possible when the stop position of the piston is outside the predetermined range. Thereby, deterioration of the glow plug can be prevented and its operability can be improved, and as a result, the engine restartability can be improved.

  As described above, according to the diesel engine automatic stop device of the present invention, the first battery for supplying power to the electric load of the vehicle including the glow plug and the second battery for supplying power to the engine starter. When the second battery is deteriorated, when the engine is restarted, the starter is driven while operating the glow plug, so that the engine restartability can be improved reliably. .

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  1 and 2 show an idle stop system E including an automatic stop device for a diesel engine according to an embodiment of the present invention. The system E includes a diesel engine 10 including a cylinder head 11 and a cylinder block 12, and the An engine control device (hereinafter referred to as an ECU) 100 for controlling the engine 10 is provided.

  In the cylinder head 11 and the cylinder block 12 of the engine 10 (see FIG. 1), four cylinders 14A to 14D are arranged in series from the engine front side. Also, a piston 16 connected to the crankshaft 15 by a connecting rod (not shown) is fitted into each cylinder 14A to 14D. A cavity 16 a that defines the combustion chamber 17 together with the cylinder head 11 is formed in the piston 16. The pistons 16 provided in the cylinders 14A to 14D are configured to move up and down with the rotation of the crankshaft 15 with a predetermined phase difference. Here, in the engine 10 that is a four-cylinder four-cycle engine, each of the cylinders 14A to 14D performs a cycle including intake, compression, expansion, and exhaust strokes with a predetermined phase difference. The numbering cylinder 14A, the numbering cylinder 14C, the numbering cylinder 14D, and the numbering cylinder 14B are configured so as to be performed with a phase difference of 180 ° (180 ° CA) in crank order.

  The cylinder head 11 is provided with a glow plug 18 for each of the cylinders 14 </ b> A to 14 </ b> D arranged such that the plug tip faces the combustion chamber 17. The cylinder head 11 is provided with a fuel injection valve 19 for each of the cylinders 14A to 14D. The fuel injection valve 19 has a branch pipe 21 provided for each of the cylinders 14A to 14D with respect to the common rail 20 that stores and distributes fuel in a high pressure state higher than the valve opening pressure (injection pressure) of the fuel injection valve 19. Are connected to each other. Each fuel injection valve 19 opens the fuel passage by electromagnetic force when energized to open the true valve of the injection nozzle by fuel pressure, and burns high-pressure fuel supplied from the common rail 20 from a plurality of injection holes at the tip of the injection nozzle. Direct injection is supplied into the cylinders 14 </ b> A to 14 </ b> D toward the cavity 16 a of the piston 16 that defines the chamber 17. In the present embodiment, a fuel pressure sensor SW <b> 1 for detecting fuel pressure is provided on the common rail 20. 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.

  The cylinder head 11 is provided with an intake port 24 and an exhaust port 25 that open toward the combustion chamber 17 in the upper part of the cylinders 14A to 14D. In addition, an intake valve 26 and an exhaust valve 27 are respectively provided at a connection portion between the ports 24 and 25 and the combustion chamber 17. An intake passage 28 and an exhaust passage 29 are connected to the intake port 24 and the exhaust port 25. The downstream side of the intake passage 28 is branched into branched intake passages 28a branched for each of the cylinders 14A to 14D, and the upstream ends of the branched intake passages 28a communicate with the surge tank 28b. A common intake passage 28c is provided on the upstream side of the surge tank 28b.

  Although schematically shown in FIG. 1, in the common intake passage 28c, an intake shutter valve (intake throttle valve) 30 capable of adjusting an intake flow amount flowing into each of the cylinders 14A to 14D, and an intake flow amount are detected. An air flow sensor SW2, an intake pressure sensor SW3 for detecting the intake pressure Pina, and an intake air temperature sensor SW4 for detecting the intake air temperature are provided. The intake shutter valve 30 is configured to be opened and closed by an actuator 30a. In the illustrated example, the intake shutter valve 30 is set so that air flows even in the fully closed state.

  The engine 10 is provided with an alternator 32 connected to the crankshaft 15 by a timing belt or the like. The alternator 32 includes a regulator circuit 33 that adjusts the amount of power generated by controlling the output voltage by controlling the current of a field coil (not shown), and based on a control signal from the ECU 100 input to the regulator circuit 33. The control of the amount of power generation corresponding to the electric load of the vehicle, the voltage of the in-vehicle battery 80, and the like is executed.

  The engine 10 is provided with a starter motor 34 for starting the engine 10. 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 ring gear 35 fixed to a flywheel (not shown) concentrically with respect to the center of rotation. When the engine 10 is restarted using the starter motor 34, the pinion gear 34b moves to a predetermined meshing position and meshes with the ring gear 35 fixed to the flywheel. It is designed to rotate.

  Further, the engine 10 is provided with two crank angle sensors SW5 and SW6 for detecting the rotation angle of the crankshaft 15, and the engine rotation speed is based on a detection signal (pulse signal) output from one crank angle sensor SW5. Ne is detected, and the rotation angle of the crankshaft 15 is detected on the basis of detection signals out of phase output from the crank angle sensors SW5 and SW6. Further, the engine 10 is operated by a water temperature sensor SW7 for detecting a coolant temperature, an accelerator opening sensor SW8 for detecting an accelerator opening corresponding to an operation amount of an accelerator pedal 36 of the vehicle, and an operation of a brake pedal 37 of the vehicle. A brake pedal sensor SW9 for detection is provided.

  The engine 10 is provided with an exhaust gas recirculation device 40. The exhaust gas recirculation device 40 includes an EGR passage 41 that circulates EGR from the exhaust passage 29 to the intake passage 28, and an EGR valve 42 provided in the middle of the EGR passage 41. The EGR valve 42 is controlled to be opened and closed by an ECU 100 described below.

  FIG. 2 shows a configuration of a power supply system according to the idle stop system E. The system E includes two batteries, a main battery 80a (first battery) and a sub battery 80b (second battery). 2 battery system.

  The main battery 80a is a battery having a relatively large capacity. The main battery 80a is always connected to the vehicle electrical load 82 via the connection line 92, and mainly supplies power to these. The vehicle electric load 82 includes a hydraulic oil generating electric oil pump 82a (load 1) for an automatic transmission, an electric power steering motor 82b (load 2), and a hill holder mechanism 82c (load) for preventing the vehicle from sliding down when stopping on a slope. 3) and a glow plug 18 (load 4). In addition to this, for example, a navigation system, audio, various lights, various meters, and the like can be cited. Here, the vehicle electrical loads 82a to 82c are required to be surely operated not only during engine operation but also during automatic stop from the viewpoint of ensuring vehicle safety. In the following description, these are referred to as necessary electrical loads. Call.

  The main battery 80 a is also connected to the starter motor 34 via a power relay 85 provided on the auxiliary line 91. The power relay 85 is controlled on and off by the ECU 100. When the power relay 85 is off, power is not supplied from the main battery 80a to the starter motor 34, and when the power relay 85 is on, power can be supplied from the main battery 80a to the starter motor 34.

  Further, the main battery 80a is always connected to the alternator 32, whereby the electric power generated by the alternator 32 is stored in the main battery 80a.

  The sub-battery 80b is a battery having a relatively small capacity, and is a battery dedicated to driving the starter motor 34 here. The sub-battery 80b is always connected to the starter motor 34 via the connection line 90, and power can be supplied to the starter motor 34. The sub battery 80 b is also connected to the alternator 32 via the charge relay 87. On / off of the charge relay 87 is controlled by the ECU 100. When the charge relay 87 is on, the electric power generated by the alternator 32 is also stored in the sub battery 80b.

  In addition, the batteries 80a and 80b are provided with voltage sensors SW10 and 11 (corresponding to battery deterioration degree detecting means) for detecting the battery voltage. The voltage sensors SW10 and 11 are connected to the ECU 100, and the ECU 100 determines deterioration of the batteries 80a and 80b based on the voltage signals from the voltage sensors SW10 and 11 (in this embodiment, as described later). Battery deterioration determination) and engine restart control based on the determination result.

  The ECU 100 includes a CPU, a memory, a counter timer group, an interface, and a microprocessor having a path connecting these units, and performs various calculations based on detection signals from input elements such as the sensors SW1 to SW11. In addition, the control signal for each actuator such as the fuel injection valve 19, the starter motor 34, or the glow plug 18 is output. For example, the fuel injection amount, injection timing, and ignition timing according to the operating conditions are calculated, and a control signal is output to the fuel injection valve 19 and the like. Further, the target opening of the intake shutter valve 30 is calculated according to the operating conditions, and a control signal is output to the actuator 30a of the intake shutter valve 30 so that the opening of the intake shutter valve 30 becomes the target opening. .

  The ECU 100 performs the determination of the driving state determination unit 101 that determines the driving state of the vehicle, the fuel injection control unit 102 that controls the fuel injection of the engine 10 based on the determination of the driving state determination unit 101, and the determination of the driving state determination unit 101. An intake air flow rate control unit 103 that adjusts the intake air flow rate that flows into the cylinder based on this, and a starter control unit that drives and controls the starter motor 34 of the engine 10 when the restart condition is satisfied based on the determination of the operating state determination unit 101 104, a glow plug control unit 105 that controls the glow plug 18, an EGR control unit 106 that drives and controls the exhaust gas recirculation device 40, and a battery deterioration level that detects the deterioration level of the battery 80 (the main battery 80a and the sub battery 80b). A determination unit 107 and a battery control unit 108 are included.

  The driving state determination unit 101 includes a fuel pressure sensor SW1, an airflow sensor SW2, an intake pressure sensor SW3, an intake air temperature sensor SW4, a crank angle sensor SW5, SW6, a water temperature sensor SW7, an accelerator opening sensor SW8, a brake pedal sensor SW9, and the like. Based on the sensor signal, this is a module that determines whether or not the automatic stop condition or restart condition of the engine 10 is satisfied or canceled, and whether or not the operating state of the engine 10 is in a low-load operating state. In addition to this, the operation state determination unit 101 determines various operation states such as the fuel pressure, the stop position of the piston 16, the in-cylinder temperature, or whether the engine 10 is rotating forward. The operation state determination unit 101 determines the stop position of the piston 16 when the engine 10 is automatically stopped, and sets an appropriate stop position SA at which the piston 16 should stop. In the present embodiment, the appropriate stop position SA of the compression stroke cylinder at the time of stop (cylinder that becomes the compression stroke when the stop of the engine 10 is completed) is, by default, 120 ° CA before compression top dead center to 100 ° CA before compression top dead center. Is set in the range. That is, in a diesel engine, it is necessary to inject fuel into the compression stroke cylinder at the time of stop, drive the piston 16 with the starter motor 34, and cause the air-fuel mixture to self-ignite in the cylinder into which the fuel has been injected. 16 is preferably stopped on the bottom dead center side. On the other hand, when the piston 16 is in the vicinity of the bottom dead center, the drive time of the starter motor 34 becomes long. Therefore, in order to achieve both reliable self-ignition and shortening of the drive time of the starter motor, by default, compression top dead It is set in a range from 120 ° CA before the point to 100 ° CA before the compression top dead center. In the present embodiment, the driving state determination unit 101 receives a detection signal from a sensor (not shown) so as to be able to determine ON / OFF of the brake pedal 37 of the vehicle, vehicle speed, and the like.

  The fuel injection control unit 102 sets the fuel injection amount corresponding to the appropriate air-fuel ratio of the engine 10 and the fuel injection timing based on the determination of the operation state determination unit 101, and based on the setting, the fuel injection valve 19 Is a module for controlling the driving of

  The intake air flow rate control unit 103 is a module that sets an appropriate intake air flow rate of the engine 10 based on the determination of the operation state determination unit 101 and drives and controls the intake shutter valve 30 based on the setting.

  The starter control unit 104 is a module that outputs a control signal to the starter motor 34 when the engine 10 is started to drive the starter motor 34.

  The glow plug control unit 105 is a module that controls driving of the glow plug 18.

  The EGR control unit 106 achieves combustion stability by opening the EGR valve 42 in a predetermined partial load operation region.

  The battery deterioration degree determination unit 107 determines the deterioration of the batteries 80a and 80b based on the voltage signal from the battery voltage sensors SW10 and SW11.

  Specifically, the deterioration determination of the battery 80a (80b) is performed based on the battery voltage Vm (Vs), the battery current Im (Is), and the battery temperature Tm (Ts) during the automatic engine stop. More specifically, for example, when determining the deterioration of the sub battery 80b, when the battery voltage Vs is less than the deterioration determination voltage Vs1, the deterioration degree of the sub battery 80b exceeds the deterioration limit value (predetermined degree). It is determined that Here, the deterioration determination voltage Vs1 is determined from a preset map (see FIG. 6) based on, for example, the battery current Is and the battery temperature Is. As shown in FIG. 6, the current Is and the deterioration determination voltage Vs1 are proportional to each other regardless of the battery temperature Ts, and the temperature Ts becomes higher as the subscript s becomes smaller. The deterioration determination voltage Vs1 increases as Ts increases. In the figure, when the battery current is Is ′ and the battery temperature is T2, the deterioration determination voltage is Vs2 ′.

  The battery control unit 108 performs charge / discharge control of the batteries 80a and 80b. Specifically, when detecting an ON signal of the key switch 83, the battery control unit 108 turns on the power relay 85 and discharges the main battery 80a to supply the discharged power to the starter motor 34. That is, the engine start by the passenger's key operation is performed by supplying power from the main battery 80 a to the starter motor 34.

  In addition, when the restart condition is satisfied, the battery control unit 108 turns off the power relay 85 and discharges the sub-battery 80b to supply the discharged power to the starter motor 34. That is, the engine restart after the automatic engine stop is performed by supplying power from the battery 80b to the starter motor 34 unless the sub battery 80b is deteriorated. Therefore, it can be said that the sub-battery 80b is a dedicated drive battery for the starter motor 34 when the engine is restarted.

  In addition, when the deterioration degree of the sub battery 80b exceeds the deterioration limit value (when the sub battery 80b is deteriorated), the battery control unit 108 turns on the power relay 85 to compensate for this deterioration. Power is also supplied from the main battery 80a to the starter motor 34. When a predetermined time has elapsed from the start of driving of the starter motor 34, the power relay 85 is switched to an off state to cut off the power supply to the starter motor 34, while the power from the main battery 80a to the glow plug 18 is switched off. Start supplying.

  Further, the battery control unit 108 discharges the main battery 80a and supplies the discharged power to the necessary electric loads 82a to 82c during the automatic engine stop (during idle stop) and the engine operation.

  Next, control examples of the automatic stop control and restart control of the engine 10 will be described.

  FIG. 3 is a flowchart centering on the automatic stop control according to the present embodiment, and FIG. 4 is a timing chart showing the transition of the engine speed Ne based on the control example of FIG.

  Referring to FIG. 3, ECU 100 waits for a preset automatic engine stop condition to be satisfied (step S <b> 10). Specifically, when the operating state of the brake pedal 37 continues for a predetermined time and the vehicle speed is equal to or lower than a predetermined value (that is, when the idle stop state of the engine 10 is assumed to continue for a predetermined time), It is determined that the automatic stop condition for engine 10 is satisfied.

  If it is determined in step S10 that the automatic stop condition is satisfied, engine speed adjustment control including alternator control is started (step Sll). Specifically, it waits for the engine rotation speed Ne to be adjusted to a predetermined first rotation speed Nl (for example, 850 rpm) (step S12). Then, the fuel supply from the fuel injection valve 19 is stopped at the timing when the engine rotation speed Ne becomes the first rotation speed Nl (YES timing in step S12) tl (step S13). At this timing tl, the ECU 100 fully closes the intake shutter valve 30 (step S14). By this control, it is possible to increase the probability that the piston 16 stops at the appropriate stop position SA.

  That is, the stop position of the piston 16 is determined by the balance between the air amount in the stop expansion stroke cylinder immediately before the engine 10 is completely stopped and the air amount in the stop compression stroke cylinder. Therefore, in order to stop the piston 16 in the proper stop position SA in the diesel engine, first, the intake flow amount of the stop expansion stroke cylinder and the stop compression stroke cylinder is temporarily reduced, and then the stop stroke compression stroke cylinder is sufficient. Therefore, it is necessary to adjust the air amount for both cylinders so that the air amount is larger than the air amount in the stop expansion stroke cylinder. Therefore, in this embodiment, the intake pressure is reduced by fully closing the intake shutter valve 30 at the timing tl, and the air amount in the stop expansion stroke cylinder and the stop compression stroke cylinder is reduced.

  When the fuel injection is stopped at the timing tl, the cylinders 14A to 14D repeat the intake, compression, expansion, and exhaust cycles with a very small intake circulation amount, and the kinetic energy of the crankshaft 15 and the like is generated by the friction resistance. When the engine 10 is consumed by pumping work of each cylinder 14A to 14D, the engine 10 descends with undulations, and the 4-cylinder 4-cycle engine reaches about 10 compression top dead centers. Stop later. In this process, the timing at which any one of the cylinders 14A to 14D exceeds the compression top dead center coincides with the timing at which the engine speed Ne undulates.

  Therefore, in the present embodiment, after fully opening the intake shutter valve 30 at the timing tl, the ECU 100 waits for the engine rotational speed Ne to become lower than a predetermined second rotational speed N2 (for example, about 400 rpm) ( Step S15). The second rotational speed N2 coincides with the timing at which the piston 16 of the stop-time compression stroke cylinder reaches the top dead center from the expansion stroke to the intake stroke.

  If YES in step S15, ECU 100 opens intake shutter valve 30 (step S16). As a result of this valve opening operation, the intake valve 26 and the exhaust valve 27 are closed with a small amount of air in the stop expansion stroke cylinder and shifted to the compression stroke, whereas the intake valve 26 is opened in the stop compression stroke cylinder. As a result, a relatively large amount of fresh air is sucked into the cylinder. As a result, the amount of air in the stop compression stroke cylinder is larger than that in the stop expansion stroke cylinder.

  Thereafter, the ECU 100 continues the alternator control and continues to adjust the stop position of the piston 16, and waits for the engine 10 to completely stop based on the detected values of the crank angle sensors SW5 and SW6 (step S17). If the engine 10 has completely stopped, the engine speed adjustment control is terminated (step S18).

  At the timing when the engine 10 is completely stopped, the piston 16 of the stop-time compression stroke cylinder passes through the bottom dead center of the intake stroke and shifts to the compression stroke. At this timing, since the intake valve 26 and the exhaust valve 27 are generally closed, a large amount of air sucked into the cylinder is compressed by the piston 16 that has passed through the bottom dead center. On the other hand, in the stop-time expansion stroke cylinder, the piston 16 compressed in the cylinder having a relatively small amount of air passes through the compression top dead center and shifts to the expansion stroke. For this reason, in the compression stroke cylinder at the time of stop, it will be stopped on the relatively bottom dead center side by the compression reaction force in the cylinder. Therefore, the piston of the stop-time compression stroke cylinder is appropriately set by appropriately setting the second rotational speed N2 and the intake air flow amount at the timing t2 when the second rotational speed N2 is detected by experiments or the like. 16 is stopped within a predetermined stop range (in this embodiment, between 100 ° CA before compression top dead center and bottom dead center), particularly at an appropriate stop position SA between 100 ° CA and 120 ° before compression top dead center. be able to.

  When the engine 10 is completely stopped, the ECU 100 stores the stop position of the piston 16 determined by the operating state determination unit 101 based on the detection of the crank angle sensors SW5 and SW6 (step S19).

  Next, engine restart control in ECU 100 will be described with reference to FIG.

  In step S20, it is determined whether or not the engine 10 is automatically stopped (idle stop). When this determination is NO, this determination is performed again. When it is YES, the process proceeds to step S21.

  In step S21, it is determined whether a restart condition is satisfied. The restart condition includes depression of the accelerator pedal 36, release of the automatic stop condition after the engine 10 is stopped, and the like. If the determination in step S21 is NO, the determination is performed again. If YES, the process proceeds to step S22.

  In step S22, the battery deterioration degree determination unit 107 performs the above-described deterioration determination to determine whether or not the deterioration degree of the sub battery 80b exceeds the deterioration limit value. If this determination is NO, step S33 is performed. If YES, the process proceeds to step S23.

  In step S <b> 23, an on signal is output from the battery control unit 108 to the power relay 85 in order to turn on the power relay 85.

  In step S24, electric power is supplied from both batteries 80a and 80b to the starter motor 34 in order to drive the starter motor 34. Specifically, both the main battery 80a and the sub-battery 80b are discharged by the battery control unit 108, and the discharge power of each of the batteries 80a and 80b is transferred to the starter motor 34 via the connection line 90 and the auxiliary line 91, respectively. In addition, the drive signal is output from the starter control unit 104 to the starter motor 34.

  In step S25, it is determined whether or not a predetermined time has elapsed since the start of driving of the starter motor 34 in step S24. When this determination is NO, the determination of step S25 is performed again, and when it is YES, step S26. Proceed to

  In step S26, the output of the on signal from the battery control unit 108 to the power relay 85 is stopped in order to turn off the power relay 85 that was turned on in step S23.

  In step S <b> 27, an operation signal is output from the glow plug control unit 105 to the glow plug 18 in order to operate the glow plug 18.

  In step S28, a drive signal is output from the fuel injection control unit 102 to the fuel injection valve 19, and fuel is injected into the stop-time compression stroke cylinder to restart combustion.

  In step S29, it is determined whether or not the glow plug 18 is in an operating state (a state in which the glow plug 18 is energized and operating). When this determination is NO, the process proceeds to step S32, while when it is YES. Proceed to step S30.

  In step S30, it is determined whether or not the engine rotational speed is equal to or higher than a predetermined rotational speed (the rotational speed at which the engine 10 starts spontaneously by in-cylinder self-ignition). If this determination is NO, the determination is performed again. On the other hand, when it is YES, it progresses to Step S31.

  In step S31, the operations of the glow plug 18 and the starter motor 34 are stopped. Specifically, stop signals are output from the starter control unit 104 and the glow plug control unit 105 to the starter motor 34 and the glow plug 18, respectively.

  In step S32, the engine restart control is terminated and the routine is shifted to normal control, and this restart control is terminated.

  In step S33 that proceeds when the determination in step S22 is NO, the starter motor 34 is driven by the power supplied from the sub battery 80b. Specifically, the battery control unit 108 discharges the sub-battery 80 b, supplies the discharged power to the starter motor 34, and outputs a drive signal from the starter control unit 104 to the starter motor 34.

  In step S34, it is determined whether or not the piston position of the stop compression stroke cylinder stored in step S19 is within a predetermined stop range. If this determination is YES, the process proceeds to step S36, and if NO, step S35 is performed. Proceed to

  In step S35, an operation signal is output from the glow plug control unit 105 to the glow plug 18 in order to operate the glow plug 18, and then the process proceeds to step S36.

  In step S36, a drive signal is output from the fuel injection control unit 102 to the fuel injection valve 19, and the combustion is restarted by injecting fuel into the stop compression stroke cylinder. Thereafter, the process proceeds to step S29.

  As described above, in the above embodiment, when the ECU 100 determines that the degree of deterioration of the sub-battery 80b is larger than the deterioration limit value (when the determination in step S22 is YES), the ECU 100 restarts the engine 10 with the power. The relay 85 is turned on so that the main battery 80a and the starter motor 34 are connected (the process of step S23 is executed), and power is supplied to the starter motor 34 from both the batteries 80a and 80b. The motor 34 is driven.

  Therefore, when the engine 10 is restarted, the shortage of power supplied to the starter motor 34 due to deterioration of the sub-battery 80b can be compensated for by the power supplied from the main battery 80a, whereby the starter motor 34 can be operated reliably. Sufficient cranking power can be obtained, and engine restartability can be improved.

  Further, in the above embodiment, the ECU 100 supplies power from the main battery 80a to the glow plug 18 when a predetermined time has elapsed from the start of driving of the starter motor 34 (executes the process of step S29).

  Thus, the power supply start timing from the main battery 80a to the glow plug 18 can be made different from the drive start timing of the starter motor 34. For this reason, when the starter motor 34 starts to be driven, Simultaneously with the power supply to the motor 34, the power supply to the glow plug 18 is executed, so that it is possible to prevent the power supplied to the necessary electric loads 82a to 82c from being lowered, and thus the safety of the vehicle. Can be secured.

  In the above embodiment, the ECU 100 turns off the power relay 85 when the power supply from the main battery 80a to the glow plug 18 is started when the predetermined time has elapsed (when the process of step S29 is executed). The power supply from the main battery 80a to the starter motor 34 is cut off (by executing the process of step S26).

  Thus, after the predetermined time has elapsed, power supply from the main battery 80a to the glow plug 18 is started, but power supply to the starter motor 34, which consumes more power than the glow plug 18, is cut off. As a result, it is possible to sufficiently ensure the power supplied to the necessary electric loads 82a to 82c even after a predetermined time has elapsed.

  Here, since the power supply from the main battery 80a to the starter motor 34 is interrupted after the predetermined time has elapsed, the starter motor 34 is driven only by the power supplied from the sub battery 80b, and the cranking power is reduced. However, since the in-cylinder temperature rises due to the operation of the glow plug 18, the restartability of the engine 10 is not impaired.

  Further, when the sub-battery 80b is deteriorated, the engine restartability is started by starting the power supply from the main battery 80a to the starter motor 34 without performing any in-cylinder heating by the glow plug 18 as described above. However, in this case, it is necessary to supply power to the starter motor that consumes a large amount of power, leading to deterioration of the main battery 80a and a reduction in the power supplied to the necessary electrical loads 82a to 82c. There is a problem. In contrast, in the above embodiment, as described above, power is supplied to the glow plug 18 with low power consumption instead of the starter motor 34 after a predetermined time has elapsed since the start of the starter motor 34. Thus, it is possible to improve engine restartability while suppressing power consumption as much as possible.

  In the above embodiment, when the ECU 100 determines that the degree of deterioration of the sub-battery 80b is equal to or lower than the deterioration limit value (when the determination in step S22 is NO), the ECU 100 restarts the compression stroke cylinder when stopping. The glow plug 18 is activated only when the piston position is outside the predetermined stop range.

  Thus, when the piston position of the compression stroke cylinder at the time of stop is outside the predetermined stop range (that is, when the compression stroke is insufficient), the in-cylinder temperature can be increased by the glow plug 18 to improve the engine restartability. On the other hand, when the piston position of the compression stroke cylinder at the time of stop is within the predetermined stop range (that is, when the compression stroke can be sufficiently secured), the glow plug 18 is deactivated to suppress the unnecessary operation. By doing so, it is possible to prevent the glow plug 18 from being deteriorated, and thus to improve the restartability of the engine 10.

  In the above embodiment, when the engine 10 is automatically stopped, the ECU 100 executes stop position control so as to stop the piston position of the stop-time compression stroke cylinder at an appropriate stop position SA within a predetermined stop range. It is like that. Specifically, the ECU 100 limits the intake air flow amount after stopping fuel injection (executes the process of step S14), and predicts that the stop-time compression stroke cylinder shifts to the last intake stroke. Since the intake air flow rate is increased at the timing t2 when the rotational speed N2 is detected (the process of step S16 is executed), the amount of air drawn into the stop compression stroke cylinder as compared to the stop expansion stroke cylinder Will increase. As a result, in the compression stroke cylinder at the time of stop, due to the compression reaction force of a relatively large amount of air filled in the cylinder, the appropriate stop position SA (from 100 ° CA before top dead center to before top dead center within the predetermined stop range). 120 ° CA).

  Thereby, when the main battery 80a is not deteriorated (when the determination in step S22 is NO), the glow plug 18 is driven when the piston position of the stop-time compression stroke cylinder is outside the predetermined stop range (step S22). (The process of S35 is performed) can be avoided as much as possible. Therefore, the operating frequency of the glow plug 18 can be reduced to prevent its deterioration, and thus the engine restartability can be improved.

(Other embodiments)
The configuration of the present invention is not limited to the above-described embodiment, but includes various other configurations. That is, in the above embodiment, when the engine 10 is automatically stopped, the stop position control is performed so as to stop the piston position of the compression stroke cylinder at the stop time at the appropriate stop position SA. There is no.

  In the above embodiment, the deterioration determination is performed based on the voltage Vs of the sub-battery 80b during the automatic engine stop. However, the present invention is not necessarily limited to this. For example, as shown in FIG. The determination may be made based on the magnitude relationship between the minimum voltage Vss and the deterioration determination voltage Vss1 based on the voltage drop at the time of engine restart. Specifically, when restarting the engine 10, first, the starter motor 34 is driven only by the sub battery 80b, and when the minimum voltage Vss at the time of the voltage drop is less than the deterioration determination voltage Vss1, the degree of deterioration of the sub battery 80b is determined. Is determined to be larger than the deterioration limit value, and power is supplied to the starter motor 34 from both the main battery 80a and the sub battery 80b.

  The present invention includes an automatic stop / restart control means for automatically stopping the engine when a predetermined automatic stop condition is satisfied, and restarting the engine after the automatic stop when a predetermined restart condition is satisfied; The present invention is useful for a diesel engine having a glow plug disposed facing each cylinder of the engine, and in particular, two batteries, a first battery for an engine starter and a second battery for an electric load of a vehicle. It is useful for the automatic stop device provided.

1 is a schematic view of an idle stop system including an engine automatic stop device according to an embodiment of the present invention. It is an electrical system diagram of an idle stop system. It is a flowchart which shows the automatic stop control in an engine control apparatus. It is a timing chart which shows transition of engine speed. It is a flowchart which shows the restart control in an engine control apparatus. It is a figure for demonstrating the deterioration determination method of a battery. FIG. 7 is a view corresponding to FIG. 6 showing another embodiment.

Explanation of symbols

SW11 battery voltage sensor (battery deterioration degree detection means)
10 Diesel engine 14 Cylinder 17 Combustion chamber 18 Glow plug 30 Intake shutter valve (intake throttle valve)
34 Starter motor (engine starter)
80a Main battery (first battery)
80b Sub battery (second battery)
82 Vehicle electrical load (electric load)
85 Power relay (switching means)
100 Engine control device (automatic stop / restart control means)

Claims (4)

An automatic stop / restart control means for automatically stopping the engine when a predetermined automatic stop condition is satisfied, and restarting the engine after the automatic stop when the predetermined restart condition is satisfied; A diesel engine automatic stop device having a glow plug disposed facing a combustion chamber of a cylinder,
A first battery for supplying power to an electrical load including at least the glow plug;
A second battery for supplying power to the starter of the engine;
A battery deterioration degree detecting means for detecting a value related to the deterioration degree of the second battery and outputting the detection information to the automatic stop / restart control means;
The automatic stop / restart control means determines whether the deterioration degree of the second battery is equal to or less than a predetermined degree based on detection information from the battery deterioration degree detection means, and the deterioration degree is equal to or less than the predetermined degree. When the engine is restarted, when the engine is restarted, the glow plug is deactivated to drive the starter. On the other hand, when it is determined that the degree of deterioration is greater than the predetermined degree, the engine is restarted. An automatic stop device for a diesel engine, characterized in that the starter is driven while the glow plug is actuated. The automatic stop device for a diesel engine according to claim 1,
The first battery is configured to be always connected to the electric load including the glow plug so as to be able to supply power,
The second battery is always connected to the starter of the engine and is configured to be able to supply power.
Switching means provided between the first battery and the starter and switching both between a connected state and a disconnected state;
The automatic stop / restart control means, when it is determined that the deterioration degree of the second battery is larger than the predetermined degree, when the engine is restarted, the switching means causes the first battery and the starter to be restarted. Is connected to drive the starter by supplying power to the starter from both the first and second batteries, and when the predetermined time has elapsed from the start of driving the starter, the switching means The first battery and the starter are switched to a non-connected state, the power supply from the first battery to the starter is cut off, and the power supply from the first battery to the glow plug is started. A diesel engine automatic stop device. The automatic stop device for a diesel engine according to claim 1,
The automatic stop / restart control means determines that the piston position of the stop-time compression stroke cylinder is within a predetermined range when the engine is restarted when the deterioration degree of the second battery is determined to be equal to or less than a predetermined degree. When the piston position of the compression stroke cylinder at the time of stop is outside the predetermined range, the starter is driven while the glow plug is operated, and the starter is driven while the glow plug is inactive. When it is determined that the degree of deterioration of the second battery is greater than a predetermined degree, the above-mentioned stop compression stroke cylinder position is determined to be within the predetermined range when the engine is restarted. An automatic stop of a diesel engine characterized by being configured to drive the starter while operating a glow plug. Apparatus. The automatic stop device for a diesel engine according to claim 3,
An intake throttle valve disposed in the intake passage of the engine;
The automatic stop / restart control means is configured to stop the piston of the stop-time compression stroke cylinder within the predetermined range by controlling the opening of the intake throttle valve when the engine is automatically stopped. Diesel engine automatic stop device, characterized in that

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