WO2008007686A1

WO2008007686A1 - Cooling controller of internal combustion engine

Info

Publication number: WO2008007686A1
Application number: PCT/JP2007/063791
Authority: WO
Inventors: Shigenori Takahashi
Original assignee: Toyota Jidosha Kabushiki Kaisha
Priority date: 2006-07-11
Filing date: 2007-07-11
Publication date: 2008-01-17
Also published as: EP2045452A1; EP2045452B1; EP2045452A4; JP2008019733A; JP4327826B2

Abstract

If the cooling water temperature is above a threshold during stoppage of an engine (1), a cooler is driven to cool the engine (1). The threshold is set as follows. If the crank angle of the engine (1) upon completion of stoppage becomes a crank angle at which the piston (4) of a cylinder (initial explosion cylinder) that is moved to a compression stroke for the first time after the next time start is located at the bottom dead center, the threshold is set at such a cooling water temperature (lower limit value) that preignition does not take place in the initial explosion cylinder at the next time start. If the crank angle of the engine (1) upon completion of stoppage becomes a crank angle where the position of the initial explosion cylinder piston (4) is located closer to the top dead center than to the bottom dead center, the threshold is set at a value higher than the above lower limit value as the position of that piston (4) provided by an crank angle becomes closer to the top dead center.

Description

Specification

Cooling control device for internal combustion engine

Technical field

[0001] The present invention relates to a cooling control device for an internal combustion engine.

Background art

[0002] An internal combustion engine mounted on a vehicle such as an automobile is required to complete starting in a short time. In general internal combustion engines that meet these demands, fuel is combusted in the cylinder that first becomes the compression stroke after the start of the start or the cylinder that becomes the compression stroke the second time after the start of the start, and after the start of the start in the compression stroke The first bombing is greeted.

[0003] Note that the internal combustion engine stops in a state where the plurality of cylinders are in the initial stages of the intake stroke, the compression stroke, the expansion stroke, and the exhaust stroke due to the pressure in the combustion chamber in each cylinder. Therefore, when the engine stop is completed, the cylinder that is initially in the compression stroke after the start of the next start is the cylinder that has stopped at the beginning of the compression stroke, and the cylinder that is in the compression stroke the second time after the start of the next start is the intake cylinder This cylinder is stopped at the beginning of the stroke.

[0004] The cylinder that reaches the compression stroke first after the start of the engine and the cylinder that reaches the compression stroke for the second time are in the initial state of the compression stroke and the initial stage of the intake stroke while the engine is stopped. The gas existing in the combustion chamber during the stop is compressed after starting. If the engine is started without a sufficient cooling period after the completion of the engine shutdown, the temperature of the gas present in the combustion chamber remains elevated by the engine heat, and the first compression stroke and the second The compression process begins. For this reason, the temperature of the gas in the combustion chamber increases during these compression strokes. This causes fuel self-ignition (pre-ignition) in the combustion chamber. Especially for an internal combustion engine that automatically stops and restarts combustion operation according to the running state of the vehicle to improve fuel efficiency, restart the engine without a sufficient cooling period after the engine stops. Since the situation is likely to occur, there will be more opportunities for the occurrence of the above-mentioned play dansions.

[0005] It should be noted that in the cylinder that reaches the compression stroke after the third start after the start of the engine, the cold air sucked into the combustion chamber is compressed in the compression stroke due to the intake passage force. It is unlikely that the above-mentioned pre-dansion will occur as the temperature of the gas in the combustion chamber becomes too high during the stroke.

[0006] In addition, in the first compression stroke after the start of the engine and the second compression stroke, it has been confirmed that the pressure in the combustion chamber is higher than that in the compression stroke during the normal combustion operation of the engine. This also causes the occurrence of play dansions. Hereinafter, the reason why the pressure in the combustion chamber increases in the first compression stroke after the start of start and the second compression stroke will be described.

[0007] During normal combustion operation before stopping in the internal combustion engine, that is, during idling operation, when the intake valve is in an open state while the piston moves in the direction of expanding the combustion chamber in the intake stroke, The air pressure is lower than the atmospheric pressure (negative pressure), and air is sucked from the intake passage into the combustion chamber. After that, the intake valve is closed while the piston is moving in the direction of expanding the combustion chamber, and the compression stroke is started. Therefore, the pressure in the combustion chamber is lower than the atmospheric pressure (negative pressure) during the intake stroke and at the beginning of the compression stroke. Therefore, when the engine stop is completed, the pressure in the combustion chamber is lower than the atmospheric pressure in the cylinder stopped at the initial stage of the compression stroke and the cylinder stopped at the initial stage of the intake stroke.

[0008] However, when a certain amount of time (for example, 1 or 2 seconds) elapses after the engine stop is completed, gas enters the combustion chamber from around the valve of the engine or around the piston ring, and the pressure in the combustion chamber is changed from a negative pressure state. Rise to atmospheric pressure. In such a state, when the engine is started and the compression of the gas in the combustion chamber is started in the cylinder in the initial stage of the compression stroke and the cylinder in the initial stage of the intake stroke, the pressure in the combustion chamber becomes large at that time. Since the pressure has increased to atmospheric pressure, the pressure in the combustion chamber after the start of compression becomes higher than that during normal combustion operation of the engine.

Yes

[0009] Based on the above, in an engine that reaches the first explosion in the first compression stroke after the start of the start or the second compression stroke, the engine is started without a sufficient cooling period after the engine stoppage is completed. If this happens, there is a risk of play dani- sion.

Patent Document 1 discloses a cooling device that is driven by a driving source different from the internal combustion engine and cools the engine with cooling water. When the cooling water temperature, which is a value corresponding to the engine temperature, is higher than a predetermined value when the engine stop is completed, the cooling water temperature does not reach the predetermined value while the engine is stopped. The cooling device is driven until it is full. In this case, since the engine temperature is lowered while the engine is stopped by setting the predetermined value to a low value, occurrence of pre-ignition at the start of the next engine start can be suppressed. However, in order to accurately suppress the play descent, it is necessary that the predetermined value is set appropriately.

[0011] That is, in the cylinder that reaches the first explosion after the start of the next engine start, the closer the piston position in the cylinder at the time of the engine stop is closer to the bottom dead center, the more the inside of the combustion chamber in the compression stroke when the first explosion is reached. The temperature and pressure of the gas are increased, and predancy is likely to occur. This is because the closer the piston position at the completion of the engine stop in the above cylinder is to the bottom dead center, the more gas is warmed in the combustion chamber during the engine stop, and the negative pressure in the combustion chamber at the completion of the engine stop is This is because the amount of increase in the pressure in the combustion chamber to the atmospheric pressure that occurs before the engine starts is increased. For this reason, it is assumed that the piston position of the cylinder at the completion of the engine stop is closest to the bottom dead center, and the engine temperature can be lowered while the engine is stopped to a value that does not cause pre-ignition at the start of the engine start. The predetermined value is set. In this way, it can be thought that the ability to avoid play-dance at the start of engine startup can be avoided.

[0012] However, when the predetermined value is set in this way, the occurrence of play precision is suppressed when the piston position force of the cylinder at the completion of the engine stop is closer to the top dead center than the position closest to the bottom dead center. The engine will be cooled more than necessary. This is because when the piston position is close to the top dead center, the gas in the combustion chamber during the compression stroke when the first explosion is started after the start of the engine is compared to when the piston is close to the bottom dead center. This is because the ease of occurrence of pre-daniation with low temperature and pressure is reduced. As described above, when the engine is cooled more than necessary, the energy for driving the cooling device is wasted and the cooling device is driven longer than necessary while the engine is stopped. Give the driver a sense of incongruity.

Patent Document 1: Japanese Patent Laid-Open No. 2001-182580

Disclosure of the invention

[0013] An object of the present invention is to cool an internal combustion engine that can suppress unnecessarily cooling of the internal combustion engine while the engine is stopped while accurately suppressing the play-dance at the start of the engine start. It is to provide a rejection control device.

[0014] In order to achieve the above object, according to one aspect of the present invention, a plurality of cylinders having pistons are provided, and one of a first compression stroke after the start of engine start and a second compression stroke is performed. There is provided a cooling control device that is applied to an internal combustion engine that is in an initial explosion. The cooling control device includes a cooling device that is driven by a drive source different from the engine to cool the engine, and a pre-ignition when the engine temperature is at the start of the engine at and after the stop of the engine. A control unit that drives the cooling device when the value is equal to or greater than a predetermined value that may be incurred, and a setting unit that sets the predetermined value according to a crank angle when the stop of the engine is completed. When the crank angle at the completion of the engine stop is the crank angle at which the piston position of the cylinder that reaches the first explosion after the next engine start is near the top dead center, the crank angle at the completion of the engine stop is The predetermined value is set to a higher value than when the piston position of the cylinder that reaches the first explosion after the next engine start is a crank angle that is close to bottom dead center.

Brief Description of Drawings

FIG. 1 is a schematic diagram showing an overall configuration of an engine and a cooling device according to a first embodiment of the present invention.

FIG. 2 is a time chart showing changes in the stroke of the combustion cycle of each cylinder, changes in the coolant temperature, changes in the driving state of the electric water pump, and changes in the driving state of the electric cooling fan.

[FIG. 3] (a) and (b) are schematic diagrams showing piston positions at the time of completion of engine stop for a cylinder that first reaches the compression stroke after the start of the next start.

FIG. 4 is a graph showing a change in threshold value with respect to a change in piston position when the engine stop is completed.

FIG. 5 is a flowchart showing an execution procedure of engine cooling control by the cooling device.

FIG. 6 is a graph showing changes in the flow rate of the electric water pump with respect to changes in the temperature difference of the cooling water temperature relative to the threshold value.

FIG. 7 is a graph showing changes in the air flow rate of the electric cooling fan with respect to changes in the temperature difference of the cooling water temperature relative to the threshold value.

FIG. 8 is a time chart showing changes in the combustion cycle stroke of each cylinder, changes in cooling water temperature, changes in the driving state of the electric water pump, and changes in the driving state of the electric cooling fan in the second embodiment of the present invention. . [FIG. 9] (a) and (b) are schematic diagrams showing the piston position when the engine stop is completed for the cylinder that reaches the compression stroke for the second time after the start of the next start.

FIG. 10 is a graph showing a change in threshold value with respect to a change in piston position when the engine stop is completed.

[Fig. 11] A graph showing another example of the change in the threshold value with respect to the change in the piston position when the engine stop is completed.

FIG. 12 is a graph showing another example of the change in the threshold value with respect to the change in the piston position when the engine stop is completed.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, a first embodiment embodying the present invention will be described with reference to FIGS.

The engine 1 shown in Fig. 1 is a series four-cylinder engine that is installed in a car and automatically stopped and restarted. In this engine 1, fuel is injected from each fuel injection valve 2 into the corresponding combustion chamber 3 during operation. The piston 4 reciprocates due to the combustion of fuel in each combustion chamber 3, whereby the crankshaft 5 that is the output shaft of the engine 1 rotates. The rotation of the crankshaft 5 is transmitted to the camshaft 6 through a belt or the like, and the opening and closing drive of the engine valves such as the intake valve 7 and the exhaust valve 8 is performed through the rotation of the camshaft 6. During the operation of the engine 1, a combustion cycle including an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke is repeated. The intake stroke, the compression stroke, the expansion stroke, and the exhaust stroke are performed in the order of the first cylinder, the third cylinder, the fourth cylinder, and the second cylinder (see FIG. 2). When starting the self-sustaining operation (combustion operation) of the stopped engine 1, the fuel injection is performed with the crankshaft 5 forcedly rotated (cranking) through the drive of the starter 15 connected to the crankshaft 5. Fuel is injected from the valve 2 into the combustion chamber 3.

Next, a device for grasping the crank angle of the engine 1 will be described.

A rotor 9 made of a magnetic material is fixed to the crankshaft 5 of the engine 1, and a large number of protrusions 9 a are formed at equal intervals in the circumferential direction on the outer peripheral edge of the rotor 9. Two crank position sensors 11 and 12 are provided in the vicinity of the rotor 9. When the rotor 9 rotates together with the crankshaft 5, signals corresponding to the protrusions 9a are output from the crank position sensors 11 and 12. In these crank position sensors 11 and 12, the rotational speed of the rotor 9 is extremely slow, such as immediately before the stop of the engine 1 is completed. Even in this case, a sensor capable of outputting a noise signal corresponding to the protrusion 9a, for example, a magnetoresistive element (MRE) sensor is used. The relative positions of the crank position sensor 11 and the crank position sensor 12 in the circumferential direction of the rotor 9 are set so that the phases of the pulse signals output from the sensors 11 and 12 are shifted from each other. Yes.

On the other hand, a rotor 13 made of a magnetic material is also fixed to the camshaft 6, and a plurality of protrusions 13 a having different circumferential lengths are arranged on the outer peripheral edge of the rotor 13 at different circumferential intervals V, It is formed! A cam position sensor 14 is provided in the vicinity of the rotor 13! /. When the rotor 13 rotates together with the camshaft 6, a signal corresponding to each projection 13 a of the port 13 is output as well as the force of the cam position sensor 14. The cam position sensor 14 can output a noise signal corresponding to the protrusion 13a even when the rotational speed of the rotor 13 is extremely slow, such as immediately before the stop of the engine 1 is completed. For example, the magnetoresistive element (MRE) sensor is used in the same manner as the crank position sensors 11 and 12.

Based on the pulse signals from the crank position sensors 11 and 12 and the pulse signal from the cam position sensor 14, the crank angle of the engine 1 is grasped. Since the MRE sensors that can output pulse signals corresponding to the protrusions 9a and 13a of the rotors 9 and 13 immediately before the completion of the stop of the engine 1 are used as the sensors 1 1, 12 and 14, the stop of the engine 1 is completed. The crank angle can be reliably grasped immediately before the end. Therefore, it is possible to grasp the crank angle when the stop of the engine 1 is completed based on the pulse signals from the crank position sensors 11 and 12 and the pulse signal from the cam position sensor 14.

[0020] Next, a cooling device for cooling the engine 1 will be described.

This cooling device includes a circulation path 16 for flowing cooling water to the engine 1. An electric water pump 17 and a radiator 18 are provided on the circulation path 16, and an electric cooling fan 19 is provided in the vicinity of the radiator 18. The electric water pump 17 and the electric cooling fan 19 are driven by a motor through power feeding from the battery 20 of the automobile, that is, driven by a driving source different from the engine 1.

[0021] When the electric water pump 17 is driven, a flow is generated in the cooling water in the circulation path 16, and the cooling water is cooled. Circulate the circulation path 16 so that the reject water passes through the radiator 18 and the engine 1. This cooling water is cooled through heat exchange with the outside air when passing through the radiator 18. Further, when the electric cooling fan 19 is driven and wind is sent toward the radiator 18, heat exchange between the cooling water and the outside air in the radiator 18 is promoted. The cooling water cooled by the radiator 18 takes heat through the heat exchange with the engine 1 when passing through the engine 1 and cools the engine 1.

[0022] The cooling efficiency of the engine 1 by this cooling device is increased as the flow rate of the electric water pump 17 is increased to increase the amount of cooling water passing through the engine 1, and the air flow rate of the electric cooling fan 19 is increased. Increasing the amount of heat exchange between the cooling water and the outside air in the radiator 18 increases.

Next, the electrical configuration of the cooling control device that drives and controls the cooling device will be described. This cooling control device is an electronic control that drives and controls various on-board equipment such as the engine 1 in the automobile. Equipped with equipment (ECU) 21! The ECU 21 functioning as a control unit and a setting unit temporarily stores a CPU that executes various arithmetic processes related to the drive control of the various mounted devices, a ROM that stores programs and data necessary for the control, and CPU calculation results. It has a RAM to store, and an input / output port for inputting / outputting signals to / from the outside.

[0024] In addition to the signals from the crank position sensors 11 and 12 and the cam position sensor 14 described above, an accelerator pedal position sensor 22 that detects the amount of depression of the accelerator pedal and an automobile speed are detected at the input port of the ECU 21. Various sensors such as a vehicle speed sensor 23 and a water temperature sensor 26 for detecting the cooling water temperature in the circulation path 16 are connected. In addition, the ECU 21's input port includes a brake switch 24 that detects whether the brake pedal is depressed, and “off”, “accessory”, “on”, and “start” depending on the driver of the car. The switch 25 is connected to the switch 25 which is switched to one of the four switching positions and outputs a signal corresponding to the current switching position. On the other hand, a drive circuit for driving the fuel injection valve 2, the electric water pump 17, the electric cooling fan 19 and the starter 15 is connected to the output port of the ECU 21.

[0025] The ECU 21 detects the vehicle and the vehicle that are grasped from the detection signals input from the sensors. Command signals are output to the drive circuit of each device connected to the output port according to the operating state of engine 1. In this way, control of fuel injection from the fuel injection valve 2, starter 15 drive control at engine start, engine 1 automatic stop / restart control, electric water pump 17 and electric cooling fan 19 drive control, etc. Control is performed by ECU21

The ECU 21 cools the engine 1 through, for example, drive control of the electric water pump 17 and the electric cooling fan 19 as follows, for example. That is, during normal combustion operation of the engine 1, the cooling water temperature in the circulation path 16 detected by the water temperature sensor 26 is used as a value corresponding to the engine temperature, and the cooling water temperature is below a target value (for example, 95 ° C). Thus, the electric water pump 17 and the electric cooling fan 19 are controlled. When the cooling water temperature falls below the target value, the drive of the electric water pump 17 and the electric cooling fan 19 is stopped. As a result, the engine 1 is properly cooled during normal combustion operation of the engine 1 so that the engine temperature does not rise excessively.

Next, starting and stopping of the engine 1 performed through drive control of the fuel injection valve 2 and the starter 15 by the ECU 21 will be described.

The engine 1 is started and stopped based on the operation of the idle switch 25 by the driver. In addition to this, for the purpose of improving fuel consumption of the engine 1, the engine 1 is automatically stopped and restarted in response to an output request to the engine 1. Hereinafter, the procedures for starting and stopping the engine 1 will be described separately for [starting and stopping based on the operation of the idle switch 25] and [automatic stopping and restarting based on whether or not the engine output is requested].

[0028] [Starting and stopping based on operation of the idle switch 25]

When engine 1 is stopped, the switch 25 is switched to “Start” when the switch 25 is switched from “Off” to “Accessory”, “On” and “Start”. At that point, the engine 1 start command is issued. Based on this start command, the starter 15 is driven to start cranking of the engine 1, and fuel is injected and supplied from the fuel injection valve 2 to the combustion chamber 3 during the cranking. Then, by burning the fuel in the combustion chamber 3 and causing the engine 1 to operate independently, the engine 1 is started. Also the luck of engine 1 When the switch 25 is switched from “On” to “Accessories” and “Off” in turn, the engine 1 stop command is issued when the switch 25 is switched to “Accessories”. Made. Based on this stop command, the combustion of fuel in the combustion chamber 3 is stopped, and the engine 1 is stopped. Thereafter, the engine speed decreases from the idle speed to “0”, and the engine 1 is stopped.

[0029] [Automatic stop and restart based on engine output request]

When the engine 1 is not in operation while the engine 1 is in operation, the combustion of fuel in the combustion chamber 3 is stopped and the engine 1 is automatically stopped. The output request to engine 1 is, for example, (A) accelerator pedal depression amount force S “0”, (B) brake pedal depressed, (C) vehicle speed is a predetermined value close to “0” Judgment is made based on whether or not all conditions such as less than a are met! When these conditions (A) to (C) are all satisfied, it is determined that there is no output request to the engine 1, in other words, it is not necessary to keep the engine 1 running, and a stop command for the engine 1 is issued. The engine 1 is automatically stopped. If an output request to engine 1 is made after engine 1 is automatically stopped, that is, if one or more of the above conditions (A) to (C) is not satisfied, A start command is issued. Based on this start command, the starter 15 is driven to start cranking of the engine 1, and fuel is injected and supplied from the fuel injection valve 2 to the combustion chamber 3 during the cranking. The engine 1 is automatically restarted by burning the fuel in the combustion chamber 3 and starting the self-sustaining operation of the engine 1.

[0030] In recent years, even if the engine 1 is started by the operation of the ignition switch 25 or automatically according to the output request of the engine 1, the start is completed early after the start of the engine. It is requested. In response to these demands, the above-mentioned engine 1 combusts fuel in the cylinder that first becomes the compression stroke after the start of the start, and reaches the first explosion after the start of the start in the compression stroke. Here, the fuel injection mode and the fuel combustion mode in the first to fourth cylinders of the engine 1 from the start of the stop of the engine 1 to the start of the next start are shown in FIG.

[0031] As can be seen from this figure, the fuel injection from the fuel injection valve 2 to the combustion chamber 3 is performed during the intake stroke, and the fuel in the combustion chamber 3 is combusted in the subsequent compression stroke and shifts to the expansion stroke. . Figure 2 In the example of (a), after the fuel injection from the fuel injection valve 2 to the combustion chamber 3 is performed in the intake stroke of the first cylinder, the engine 1 is stopped when the same cylinder shifts to the compression stroke. (Time Tl). After that, when the engine 1 start command is issued (time Τ3), the engine 1 starts to start, and the fuel present in the combustion chamber 3 burns in the first cylinder that is in the compression stroke first after the start of the engine. The first explosion after the start of 1 will start. In this way, by starting the first explosion in the cylinder that is in the compression stroke first after the start of the engine 1, the engine 1 can be operated independently at an early stage after the start of the start. In the following, the cylinder that is first in the compression stroke after the start of the engine 1 is referred to as “first explosion cylinder” as necessary.

[0032] By the way, in the first compression stroke after the start of the engine 1, the temperature of the gas in the combustion chamber 3 and the pressure in the combustion chamber 3 are compared with those during normal combustion operation of the engine 1. High for the reasons listed in the "Technology" column. For this reason, in the cylinder that first reaches the compression stroke after starting, there is a risk that self-ignition (prediction) of the fuel in the combustion chamber 3 may occur.

[0033] Therefore, the cooling power S of the engine 1 by the cooling device described above is performed not only during normal combustion operation but also when the engine 1 is stopped and thereafter. Specifically, as shown in FIG. 2 (b), the cooling water temperature in the circulation path 16 representing the temperature of the engine 1 is preliminarily set at and after the stop of the engine 1 (after time T1). When it is equal to or greater than the predetermined threshold, the electric water pump 17 is driven as shown in FIG. 2 (c), and the electric cooling fan 19 is driven as shown in FIG. 2 (d). . As a result, the engine 1 is cooled, and it is possible to suppress the occurrence of play dandelion in the first compression stroke after the start of the next start. Thereafter, when the cooling water temperature becomes lower than the above threshold (time T2), the electric water pump 17 and the electric cooling fan 19 are stopped, and the cooling of the engine 1 by the cooling device is stopped.

[0034] Splaying force S of play mushroom generation in the cylinder (first explosion cylinder) that is first in the compression stroke after the start of engine 1 is started, piston of the first explosion cylinder at the time of completion of stop of engine 1 immediately before the start of the start What changes depending on the position of 4 is as described in the [Background Technology] column. That is, the position of the piston 4 of the first explosion cylinder is dead as shown in Fig. 3 (a). At the point position, the temperature of the gas in the combustion chamber 3 and the pressure in the combustion chamber 3 in the first compression stroke are the highest, so the predancy is most likely to occur. It becomes. In addition, when the position of piston 4 of the first explosion cylinder is closer to the top dead center than the bottom dead center as shown in FIG. The temperature of the gas in the combustion chamber 3 and the pressure in the combustion chamber 3 during the contraction stroke are lowered, and the ease of occurrence of the above-mentioned regeneration is gradually reduced. Therefore, assuming that the position of piston 4 of the first explosion cylinder is at the bottom dead center, if the threshold value is set to a low value to avoid the above-mentioned play-dance, It is not possible to achieve accurate control.

[0035] However, when the actual position of the piston 4 of the first explosion cylinder is closer to the top dead center than the bottom dead center, the threshold value is too low to accurately suppress the play-dance. Thus, at the completion of the stop of the engine 1 and thereafter, the cooling of the engine 1 by driving the cooling device is performed more than necessary. This results in wasteful power consumption for driving the electric water pump 17 and the electric cooling fan 19. Furthermore, since it takes a long time to lower the coolant temperature of engine 1 below the threshold value, it takes time, so the drive stop timing of the electric water pump 17 and the electric cooling fan 19 (time ijT2 in FIG. 2) is delayed. As a result, the driver feels uncomfortable.

Therefore, in the present embodiment, the above-described threshold value is variably set according to the crank angle when the stop of the engine 1 is completed. More specifically, when the crank angle at the completion of the stop of the engine 1 is the crank angle at which the position of the piston 4 of the cylinder (first explosion cylinder) that becomes the compression stroke first after the start of the next start becomes the bottom dead center. The above threshold value is set to the lowest value (cooling water temperature) that can accurately suppress the occurrence of play dandelion in the first explosion cylinder at the start of the next start. In addition, the crank angle at the completion of the stop of the engine 1 is such that the position of the piston 4 of the cylinder (first explosion cylinder) that becomes the compression stroke first after the start of the next start is closer to the top dead center than the bottom dead center. When the crank angle is reached, the threshold value is gradually set higher as the crank angle at which the piston 4 is closer to the top dead center.

FIG. 4 shows the relationship between the position of the piston 4 of the cylinder 4 in the first compression stroke after the start of the next start (first explosion cylinder) when the engine stop is completed and the above-described threshold value. That is, the first explosion cylinder When the position of the piston 4 is at the bottom dead center, the above threshold value is a low value that can accurately suppress the reproduction in the first explosion cylinder at the next start. In addition, when the position of piston 4 of the first explosion cylinder is closer to the top dead center than the bottom dead center, the threshold value gradually becomes higher as the position of piston 4 is closer to the top dead center. Can be changed. For this reason, the threshold value will not be too low to accurately suppress the occurrence of play dandruff in the first explosion cylinder at the next engine start. Therefore, the cooling of the engine 1 by the cooling device is not performed more than necessary.

[0038] With the above, it is possible to suppress the cooling of the engine 1 more than necessary by the cooling device while the engine is stopped, while accurately suppressing the occurrence of play dandelion in the first explosion cylinder at the next engine start. As a result, the occurrence of the above-described problems can be avoided.

Next, the drive control procedure of the cooling device will be described with reference to the flowchart of FIG. 5 showing the cooling control routine. This cooling control routine is periodically executed through the ECU 21 by, for example, a time interruption every predetermined time.

[0040] In step S101, the ECU 21 determines whether or not it is the time when the stop of the engine 1 is completed. When it is determined that it is the time when the stop of the engine 1 is completed, the ECU 21 proceeds to step S102. In step S102, the ECU 21 detects the crank angle at the completion of the engine stop based on the signals from the crank position sensors 11, 12 and the cam position sensor 14, and sets the above-described threshold based on the crank angle. In subsequent step S103, the ECU 21 determines whether or not the engine 1 is stopped. If the determination is negative, engine 1 is performing normal combustion operation. In this case, the ECU 21 proceeds to step S109 to perform normal cooling control, i.e., the electric water pump 17 and the electric cooling fan 19 are set so that the cooling water temperature is equal to or lower than the target value (95 ° C in this embodiment). Drive control.

[0041] On the other hand, if a negative determination is made in step S103, it means that the engine 1 has been stopped and has been stopped thereafter. In this case, the ECU 21 is based on the condition that the coolant temperature is equal to or higher than the above threshold value (S104: YES) and that the remaining battery level, which is the stored amount of the battery 20, is equal to or higher than the lower limit (S105: YES). , A process to drive the cooling device while the engine is stopped ( S106 and S107) are executed. The battery remaining amount is obtained based on the amount of charge of the battery 20 by the generator mounted on the vehicle, the amount of discharge from the battery 20 when operating the electric device mounted on the vehicle, and the like.

[0042] The process for driving the cooling device while the engine is stopped includes the process of step S106 for calculating the temperature difference of the cooling water temperature with respect to the threshold value, the flow rate of the electric water pump 17 and the electric motor pump according to the temperature difference. And the process of step S107 for controlling the air flow rate of the cooling fan 19. More specifically, as the temperature difference becomes larger, the pump 17 is controlled so that the flow rate of the electric water pump 17 gradually increases as shown in FIG. 6, and the electric cooling as shown in FIG. The fan 19 is controlled so that the air flow rate of the fan 19 gradually increases. Thereby, the cooling of the engine 1 by the cooling water while the engine is stopped is performed more strongly as the cooling water temperature is higher than the threshold value, and is decreased as the cooling water temperature approaches the threshold value.

[0043] As a result of cooling the engine 1 with the cooling water as described above, if the cooling water temperature becomes lower than the threshold value in step S104, the ECU 21 proceeds to step S108, and the electric water pump 17 and the electric cooling fan 19 are driven. Stop.

The embodiment described above in detail has the following advantages.

(1) When the crank angle at the completion of the stop of engine 1 is the crank angle at which piston 4 of the cylinder (first explosion cylinder) that is first in the compression stroke after the start of the next start is located at the bottom dead center, the above threshold value is At the start of the next start, no pre-dansion occurs in the first-explosion cylinder! / And the cooling water temperature (lower limit) is set, so the occurrence of pre-dansion can be suppressed accurately. Furthermore, when the crank angle at the completion of the stop of the engine 1 is the crank angle at which the position of the piston 4 of the cylinder that is first in the compression stroke after the start of the next start is closer to the top dead center than the bottom dead center The threshold value is set to a value higher than the lower limit value as the crank angle at which the piston 4 is closer to the top dead center. As a result, while the occurrence of the above-mentioned playanch is accurately suppressed, it is possible to suppress the above threshold value from being too low for accurately suppressing the playaidness, and the engine 1 while the engine 1 is stopped. The cooling more than necessary can be suppressed.

[0045] (2) When cooling the stopped engine 1, if the cooling water temperature is higher than the threshold value, The flow rate of the dynamic water pump 17 and the airflow rate of the electric cooling fan 19 were increased, and the flow rate of the electric water pump 17 and the airflow rate of the electric cooling fan 19 were gradually decreased as the cooling water temperature became closer to the above threshold. . For this reason, the cooling of the stopped engine 1 is performed more strongly as the cooling water temperature is higher than the threshold value, and is decreased as the cooling water temperature approaches the threshold value. Therefore, the cooling water temperature can be quickly made lower than the threshold without driving the electric water pump 17 and the electric cooling fan unnecessarily.

[0046] (3) Engine 1 that automatically stops and restarts combustion operation has more opportunities to start without taking too much time after the completion of stop of engine 1, and play Danish at the start of the start There will be more opportunities for Yong. However, it is possible to suppress the cooling of the stopped engine 1 more than necessary while appropriately suppressing the occurrence of such playdansion.

Next, a second embodiment of the present invention will be described based on FIG. 8 and FIG.

In this embodiment, in order to complete the start-up of the engine 1 in a short time, the fuel is burned in the cylinder that becomes the compression stroke for the second time after the start of the start, and the first explosion after the start of the start is reached during the compression stroke. It is a thing.

[0048] Fig. 8 (a) shows the fuel injection mode and the fuel combustion mode in the first to fourth cylinders of the engine 1 from the start of the stop of the engine 1 to the start of the next start in this embodiment. It is a time chart. In the example in this figure, engine 1 has been stopped when the first cylinder has transitioned from the intake stroke to the compression stroke and the third cylinder has transitioned from the exhaust stroke to the intake stroke (time Tl). . In this embodiment, the fuel injection in the intake stroke immediately before the completion of the stop is not performed in the cylinder that is in the compression stroke when the stop of the engine 1 is completed (the first cylinder in FIG. 8A). After that, when the engine 1 is instructed to start (time Τ3), the engine 1 starts to start and the fuel injection valve 2 in the cylinder (first cylinder in FIG. 8 (a)) that is the first in the intake stroke after the start is started. To the combustion chamber 3. When the third cylinder reaches the compression stroke, that is, when the second compression stroke after the start of the start is reached, the fuel existing in the combustion chamber 3 of the third cylinder burns, and the engine 1 It will be the first explosion after starting. In the following, the cylinder that is in the compression stroke for the second time after the start of the engine 1 will be referred to as “first explosion cylinder” as necessary. [0049] By the way, even in the second compression stroke after the start of the engine 1, the temperature of the gas in the combustion chamber 3 and the pressure in the combustion chamber 3 are compared with those in the normal combustion operation of the engine 1, It becomes high for the reason described in the “Background Art” column. For this reason, even in a cylinder that reaches the compression stroke for the second time after the start of start-up, there is a possibility that pre-danimation in the combustion chamber 3 may occur. The cooling device is driven so that the cooling water temperature of the engine 1 becomes less than the threshold value as shown in FIG. 8 when the stop of the engine 1 that suppresses such play dandy is completed and thereafter.

[0050] Then, the above threshold value prevents the engine 1 from being cooled more than necessary by the cooling device while the engine is stopped, while accurately suppressing the occurrence of play dandy at the start of starting. It is set according to the crank angle at the time of completion.

[0051] More specifically, FIG. 9 (a) shows the position of the piston 4 of the cylinder (first explosion cylinder) in which the crank angle when the stop of the engine 1 is completed becomes the compression stroke for the second time after the start of the next start. When the crank angle is closest to the bottom dead center, the above threshold is the lowest value, and the value that can accurately suppress the occurrence of play dandruff in the first explosion cylinder at the start of the next start. Set to (cooling water temperature). This is because the temperature of the gas in the combustion chamber 3 during the second compression stroke when the position of the piston 4 above the first explosion cylinder is closest to the bottom dead center as shown in FIG. 9 (a). This is because the pressure in the combustion chamber 3 is the highest and the predancy is most likely to occur.

[0052] Further, as shown in FIG. 9 (b), the position of the piston 4 of the cylinder (first explosion cylinder) in which the crank angle at the completion of the stop of the engine 1 is the second compression stroke after the start of the next start is shown. When the crank angle is closer to the top dead center than the position closest to the bottom dead center (Fig. 9 (a)), the higher the crank angle the piston 4 is closer to the top dead center. Then, gradually set the threshold value to a higher value. This is because when the position of the piston 4 is closer to the top dead center than the position closest to the bottom dead center (FIG. 9 (a)) as shown in FIG. ! /, The lower the position, the lower the gas temperature in the combustion chamber 3 and the pressure in the combustion chamber 3 in the second compression stroke, so It is for becoming.

[0053] FIG. 10 shows the piston of the cylinder (first explosion cylinder) that is in the compression stroke for the second time after the start of the next start. 4 shows the relationship between the position when the engine stop is completed and the threshold value described above. In other words, when the position of the piston 4 of the first explosion cylinder is closest to the bottom dead center, the threshold value is a low value that can accurately suppress the play-dance in the first explosion cylinder at the next start. Further, when the position of the piston 4 of the first explosion cylinder is closer to the top dead center than the position closest to the bottom dead center, the threshold value gradually increases as the position of the piston 4 approaches the top dead center. It can be changed to a higher value. For this reason, the threshold value will not be too low to accurately suppress the occurrence of play dans in the first explosion cylinder at the next engine start. Engine 1 will not be cooled more than necessary.

The embodiment described in detail above has the following advantages.

(4) When the crank angle force S at the completion of the stop of engine 1 is the crank angle at which piston 4 of the cylinder (first explosion cylinder) that is in the compression stroke for the second time after the start of the next start is located closest to the bottom dead center In this case, the above threshold is set to the first explosion cylinder at the start of the next start so that no play Danish occurs! /, And the cooling water temperature (lower limit) is set, so that the occurrence of play Danish is accurately suppressed. That power S. Furthermore, the crank angle at the completion of the stop of the engine 1 is such that the position of the piston 4 of the cylinder that becomes the compression stroke for the second time after the start of the next start is closer to the top dead center than the position closest to the bottom dead center. When the angle is an angle, the threshold value is set to a value higher than the lower limit value as the crank angle at which the position of the piston 4 approaches the top dead center. As a result, it is possible to prevent the occurrence of the above-mentioned playanchion while suppressing the threshold value from being too low for accurately suppressing the above-mentioned playaidness. Cooling more than necessary can be suppressed.

[0055] (5) The same advantages as (2) and (3) of the first embodiment can be obtained.

In addition, each said embodiment can also be changed as follows, for example.

In the first embodiment, the force S is linearly changed as shown in FIG. 4, and the threshold value may be changed stepwise instead. For example, the threshold value may be changed in two steps as shown in FIG. 11 or may be changed in three steps or more. In this case, the same advantage as (1) of the first embodiment can be obtained. If the threshold value is changed linearly as in the first embodiment, cooling of the engine 1 is suppressed more than necessary while the engine 1 is stopped. Therefore, it is possible to more appropriately achieve both the control of the play and the suppression of the occurrence of play dandy at the start of the start of the engine 1 next time.

In the second embodiment, as shown in FIG. 10, the force S is linearly changed as shown in FIG. 10, and the threshold value may be changed stepwise instead. For example, the threshold value may be changed in two steps as shown in FIG. 12, or may be changed in three steps or more. In this case, the same advantage as (4) of the second embodiment can be obtained. If the threshold is changed to linear as in the second embodiment, the cooling of the engine 1 is suppressed more than necessary when the engine 1 is stopped, and the next time the start-up of the engine 1 is started. Suppression of generation can be more suitably achieved.

[0057] The flow rate of the electric water pump 17 while the engine 1 is stopped does not necessarily need to be gradually changed according to the temperature difference of the cooling water temperature with respect to the threshold as shown in FIG. May be changed.

[0058] The flow rate of the electric water pump 17 is fixed! /, Or! /.

The amount of air blown by the electric cooling fan 19 when the engine 1 is stopped is not necessarily changed gradually according to the temperature difference as shown in FIG. 7, but may be changed stepwise according to the temperature difference. Good.

[0059] The amount of air blown by the electric cooling fan 19 is fixed! /!

As a parameter representing the temperature of the engine 1, force using the cooling water temperature in the circulation path 16 may be replaced with another parameter such as the lubricating oil temperature of the engine 1.

[0060] Stopping automatically in response to an output request · Power stop applying the present invention to the engine 1 to be restarted · Applying the present invention to an engine that is started only by the idance switch 25 by the driver Also good.

The present invention may be applied to a port injection type engine in which fuel is injected into a force intake port 1 in which the present invention is applied to a direct injection type engine 1 that injects fuel into the combustion chamber 3.

The present invention may be applied to engines of types other than four cylinders, such as in-line six cylinders, V type six cylinders, and V type eight cylinders.

Claims

The scope of the claims

[1] A cooling control device that is applied to an internal combustion engine that includes a plurality of cylinders having pistons and that undergoes an initial explosion in one of a first compression stroke after the start of engine start and a second compression stroke.

A cooling device that is driven by a driving source other than the engine to cool the engine, and a predetermined value that may cause pre-ignition when starting the engine at and after the completion of the stop of the engine. A control unit for driving the cooling device, and

A setting unit that sets the predetermined value in accordance with a crank angle at the time when the engine stop is completed. The setting unit is configured such that the crank angle at the completion of the engine stop reaches the first explosion after the next engine start. Is the crank angle at the position close to top dead center, the crank angle at the completion of engine stop is the crank angle at which the piston position of the cylinder that reaches the first explosion after the next engine start is close to bottom dead center A cooling control device comprising: setting the predetermined value to a higher value than sometimes.

[2] The setting unit gradually increases the predetermined value as the crank angle at the completion of the engine stop is a crank angle at which the piston of the cylinder that reaches the first explosion after the next engine start is positioned near the top dead center. 2. The cooling control device according to claim 1, wherein the cooling control device is set to a high value.

[3] The cooling device includes an electric pump that supplies cooling water to the engine, and the control unit includes

3. The cooling control device according to claim 1, wherein the flow rate of the electric pump is increased as the engine temperature is higher / lower than the predetermined value.

[4] The cooling device includes an electric pump that circulates cooling water so as to pass through the engine, and an electric fan that cools the cooling water by blowing air, and the control unit is configured to change the engine to the predetermined value. The cooling control device according to claim 1 or 2, wherein the amount of air blown by the electric fan is increased as the temperature is higher.

[5] The engine is automatically stopped when the automatic stop condition is satisfied during execution of the combustion operation, and is automatically restarted when the automatic start condition is satisfied while the combustion operation is stopped. The cooling control device according to any one of claims 1 to 4, wherein the cooling control device is provided.