JP2009264224A - Start control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance startability while preventing fuel hammer and dilution of engine oil. <P>SOLUTION: The start control device 1 of the internal combustion engine is for a vehicle provided with the internal combustion engine 11 capable of using a fuel 161 containing alcohol, a motor 17 for rotating the internal combustion engine at least till the internal combustion engine starts and a battery 14 for supplying electric power to the motor. The start control device of the internal combustion engine is provided with a valve timing change means 12 capable of changing valve timing of an air inlet valve 113 of the internal combustion engine and an alcohol concentration detection means 21 for detecting concentration of alcohol contained in the fuel and a control means 15 for controlling the valve timing change means to change the valve timing in accordance with the detected concentration on starting the internal combustion engine. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an internal combustion engine capable of using a fuel including gasoline and alcohol, and an internal combustion engine start control device in a vehicle such as a hybrid vehicle including a motor / generator, and more particularly to a technical field of valve timing control. .

  As this type of start control device, for example, a control device has been proposed in which the cranking speed and the fuel injection amount are determined at the start in accordance with the alcohol concentration in the fuel and the engine coolant temperature. Here, in particular, the cranking speed is set so as to decrease as the alcohol concentration increases and the cooling water temperature decreases, and the fuel injection amount increases as the alcohol concentration increases and the cooling water temperature decreases. A technique for improving the starting characteristics by setting to (see Patent Document 1) is disclosed. Alternatively, there has been proposed a control device that controls the valve opening characteristics with a variable valve mechanism according to the state of the battery when the internal combustion engine is started (see Patent Document 2).

  Alternatively, a valve timing adjusting device that changes the closing timing of the intake valve in accordance with the coolant temperature of the internal combustion engine at the time of starting has been proposed. Here, in particular, a technology is disclosed that facilitates cold start by advancing the closing timing when the coolant temperature is low (see Patent Document 3). Alternatively, the lower the cranking rotation speed and the lower the engine water temperature, the target value for the intake valve closing timing is set to the advance side, and fuel injection is performed when the actual intake valve closing timing matches the target value. A start control device has been proposed (see Patent Document 4).

  Alternatively, there has been proposed a start control device that gradually increases the target torque of the output torque of the motor that cranks the engine and limits the magnitude to the maximum torque determined by the coolant temperature. Here, in particular, a technique for suppressing wasteful consumption of battery power by keeping the target torque low during cold is disclosed (see Patent Document 5).

JP 2007-211659 A JP 2006-217992 A JP-A-10-227236 JP 2000-154753 A Japanese Patent Laid-Open No. 11-153075

  However, according to the technique described in Patent Document 1, the fuel injection amount increases as the alcohol concentration in the fuel increases and the coolant temperature decreases. Then, there is a technical problem that unburned fuel accumulates in the combustion chamber and a fuel hammer may occur or engine oil may be diluted by unburned fuel.

  Further, according to the techniques described in Patent Documents 2 to 5, alcohol fuel is not considered. Then, when the techniques described in Patent Documents 2 to 5 are applied to an internal combustion engine that can use alcohol fuel, there is a technical problem that an expected effect may not be obtained.

  The present invention has been made in view of the above problems, for example, and proposes a start control device for an internal combustion engine that can improve startability while preventing dilution of a fuel hammer and engine oil. Let it be an issue.

  In order to solve the above problems, an internal combustion engine start control device according to the present invention is an internal combustion engine that can use a fuel containing alcohol, and a motor that rotates the internal combustion engine at least until the internal combustion engine starts. And a start timing control device for the internal combustion engine in a vehicle comprising a battery for supplying electric power to the motor, the valve timing changing means capable of changing the valve timing of the intake valve of the internal combustion engine, and alcohol contained in the fuel An alcohol concentration detecting means for detecting the concentration of the fuel, and a control means for controlling the valve timing changing means so as to change the valve timing according to the detected concentration when starting the internal combustion engine. .

  According to the start control device for an internal combustion engine of the present invention, the vehicle on which the start control device is mounted can use fuel containing alcohol, for example, an internal combustion engine that is an engine, at least until the internal combustion engine is started. A motor for rotating the internal combustion engine and a battery for supplying electric power to the motor. Here, “the internal combustion engine is started” means that a normal combustion state is obtained in the combustion chamber, or that the internal combustion engine is in a complete explosion state. In other words, it means that cranking in the internal combustion engine is completed. “Rotating the internal combustion engine” typically means cranking the cranking shaft of the internal combustion engine.

  The “motor” according to the present invention is typically a motor for driving the vehicle, but may be a dedicated motor for cranking an internal combustion engine such as a starter motor. Or the motor implement | achieved in a motor generator (motor generator) may be sufficient. That is, as long as it can function as a motor, it may typically mean a motor / generator used in a hybrid vehicle.

  The “fuel containing alcohol” according to the present invention is typically a mixed fuel of alcohol and another fuel such as gasoline (ie, alcohol mixed fuel), but is a fuel containing only alcohol. There may be.

  For example, valve timing changing means such as a variable valve mechanism can change the valve timing of the intake valve of the internal combustion engine. The valve timing changing means may be capable of changing the valve timing of the exhaust valve in addition to the intake valve.

  The alcohol concentration detection means detects the concentration of alcohol contained in the fuel. The concentration may be detected directly by, for example, installing a concentration sensor in the fuel tank, or by detecting the amount of fuel supplied to the internal combustion engine and the air-fuel ratio, for example. You may detect indirectly from the relationship between quantity and an air fuel ratio.

  For example, the control means configured to include a memory, a processor, and the like controls the valve timing changing means so as to change the valve timing according to the detected concentration when starting the internal combustion engine. Here, “when the internal combustion engine is started” typically means, for example, a time point when a start command signal is transmitted from an electronic control unit (ECU) or a cranking start time point of the internal combustion engine. Furthermore, it may include the time when the start command signal is transmitted or the time that is slightly later than the cranking start time, or the time when the start command signal is transmitted or when a predetermined minute time has elapsed from the cranking start time. Good.

  Note that “change the valve timing according to the detected concentration” typically means a compression end temperature at which the internal combustion engine can be started within a predetermined period according to the detected concentration. It means that the valve timing is changed so that (that is, the compression pressure) can be obtained. Specifically, for example, the valve timing is advanced as the detected concentration is higher. Here, the “predetermined period” may be set according to, for example, the amount of power consumed until the internal combustion engine is started.

  Typically, in the initial stage of cranking of the internal combustion engine, the control means controls the valve timing changing means so that the valve timing is such that the rotational speed of the internal combustion engine is likely to increase. At a relatively high stage, the valve timing changing means is controlled so that the valve timing is such that a compression end temperature at which the internal combustion engine can be started is obtained.

  According to the research of the present inventor, the fuel containing alcohol has lower volatility than gasoline fuel, and the volatility varies depending on the concentration of alcohol contained in the fuel. In particular, in a low temperature environment such as -30 degrees Celsius, the fuel is difficult to evaporate. Therefore, in order to obtain an air-fuel mixture that can start the internal combustion engine, the amount of fuel supplied must be increased. Then, due to unburned fuel, for example, fuel hammer, engine oil may be diluted.

  In addition, in an internal combustion engine employing the Atkinson cycle, the closing timing of the intake valve is late, and in order to obtain a predetermined compression pressure, the internal combustion engine must be cranked for a relatively long time. Then, it has been found that there is a possibility that the internal combustion engine cannot be started depending on the remaining charge of the battery.

However, in the present invention, the valve timing changing means is controlled by the control means so as to change the valve timing in accordance with the detected concentration. As a result, the compression end temperature at which the internal combustion engine can be started can be obtained within a predetermined time, and the internal combustion engine can be quickly started (that is, completed) (that is, the startability can be improved). it can). As a result, the amount of fuel supplied until the internal combustion engine is started can be suppressed, and for example, fuel hammer, dilution of engine oil, and the like caused by the supplied fuel can be prevented. In addition, battery consumption can be reduced, which is very advantageous in practice.
In one aspect of the start control device for an internal combustion engine of the present invention, the control means includes valve timing setting means for setting a target valve timing that is a target of the valve timing in accordance with the detected concentration, and the valve The valve timing changing means is controlled so that the timing becomes the set target valve timing.

  According to this aspect, for example, the valve timing setting unit configured by including a memory, a processor, and the like sets a target valve timing that is a target of the valve timing in accordance with the detected concentration. The “target valve timing” is not limited to the valve timing at which the compression end temperature at which the internal combustion engine can be started is obtained, and may mean, for example, the valve timing after a minute time has elapsed. In this case, the rate of change of the valve timing with respect to the time axis can be changed relatively easily.

  Specifically, for example, the valve timing is hardly changed at the initial stage of cranking of the internal combustion engine, and the valve timing is increased when the rotational speed of the internal combustion engine is increased and the rotational speed of the internal combustion engine is relatively high. It can be changed so that the compression end temperature at which the internal combustion engine can be started relatively quickly can be obtained.

  The control means controls the valve timing changing means so that the actual valve timing becomes the set target valve timing. Note that “so as to achieve the target valve timing” is not limited to the case where the actual valve timing and the target valve timing completely match, and may include the case where they match within a predetermined range such as an error range.

  In an aspect including the valve timing setting means, the information processing means further includes information storage means for storing information related to the internal combustion engine until the internal combustion engine is started, and the valve timing setting means is configured to store the information from the stored information. The target valve timing may be set by identifying information corresponding to the detected concentration.

  If comprised in this way, the learning function can be provided to the said starting control apparatus. In particular, when there is a deviation from the design at the time of manufacture due to, for example, aging, the target valve timing can be set taking into account the effects of aging, etc., which is very advantageous in practice. is there.

  For example, the information storage means configured to include a memory, a processor, and the like stores information related to the internal combustion engine until the internal combustion engine is started. Here, “until the internal combustion engine is started” typically means, for example, that the internal combustion engine has completely exploded from the time when the start command signal is transmitted from the ECU or the cranking start time of the internal combustion engine. Means the period until it is determined. Further, the “information relating to the internal combustion engine” means, for example, the time until the internal combustion engine is started, the valve timing, the rotation speed, the temperature, the amount of fuel supplied, the alcohol concentration, etc. , Meaning relevant information. The information storage means is not limited to the time until the internal combustion engine is started, and may always store information related to the internal combustion engine.

  The valve timing setting means specifies information corresponding to the detected concentration from the accumulated information and sets the target valve timing. The valve timing setting means may specify information corresponding to a plurality of physical quantities or parameters such as the temperature of the internal combustion engine, for example, in addition to the detected concentration, and set the target valve timing.

  In the aspect including the valve timing setting means, when the internal combustion engine is rotated by the motor, the remaining charge detection means for detecting the remaining charge of the battery, and according to the detected remaining charge, Valve timing correction means for correcting the set target valve timing, and the control means controls the motor so as to output torque corresponding to the detected remaining charge amount, The valve timing changing means may be controlled so that the timing becomes the corrected target valve timing.

  If comprised in this way, while being able to suppress the electric power consumption of the battery until starting an internal combustion engine, it can prevent that an internal combustion engine is not started by power shortage, and is very advantageous practically. is there.

  In particular, when using a low-temperature and high-concentration alcohol fuel (for example, 80% alcohol concentration), in order to start the internal combustion engine, the valve timing must be advanced and the cranking rotational speed must be increased. Then, it has been found by the inventor's research that the power consumption in the motor is relatively large and the battery may deteriorate early.

  In the present invention, however, the control means controls the motor so that torque corresponding to the detected remaining charge is output, and the valve timing changing means so that the valve timing becomes the corrected target valve timing. Is controlled. Thereby, power consumption can be optimized, and as a result, early deterioration of the battery can be prevented.

  The remaining charge detection means detects the remaining charge of the battery when the internal combustion engine is cranked by the motor. Here, “when the internal combustion engine is cranked by the motor” typically means after the cranking of the internal combustion engine is started and before the internal combustion engine is started.

  For example, a valve timing correction unit configured with a memory, a processor, etc. corrects the set target valve timing in accordance with the detected remaining charge. The control means controls the valve timing changing means so that the valve timing becomes the corrected target valve timing while controlling the motor so that a torque corresponding to the detected remaining charge amount is output.

  In another aspect of the start control apparatus for an internal combustion engine of the present invention, the control means controls the valve timing changing means so that the valve timing is advanced as the detected concentration is higher.

  According to this aspect, since the valve timing changing means is controlled so that the valve timing is advanced as the detected concentration is higher by the control means, the fuel can be vaporized earlier, which is very practical. Is advantageous.

  In another aspect of the start control device for an internal combustion engine of the present invention, the control device further comprises temperature detection means for detecting the temperature of the internal combustion engine, and the control means is provided on the condition that the detected temperature is lower than a temperature threshold. The valve timing changing means is controlled to change the valve timing in accordance with the detected concentration.

  According to this aspect, the temperature detection means detects the temperature of the internal combustion engine. The temperature detecting means may directly detect the temperature of the internal combustion engine, for example, by a temperature sensor or the like, or detect a physical quantity or parameter having some relationship with the temperature of the internal combustion engine, such as the temperature of cooling water. Thus, the temperature of the internal combustion engine may be indirectly detected from the detected physical quantity or parameter.

  The control means controls the valve timing changing means so as to change the valve timing in accordance with the detected concentration on condition that the detected temperature is lower than the temperature threshold. On the other hand, the control means typically controls the valve timing changing means so as not to change the valve timing on the condition that the detected temperature is higher than the temperature threshold.

  Here, the “temperature threshold” according to the present invention is a value that determines whether or not to control the valve timing changing means so as to change the valve timing in accordance with the detected concentration. It is a value set as a variable value according to some parameter. Such a temperature threshold is, for example, -20 degrees Celsius, and the relationship between the temperature of the internal combustion engine and the valve timing at which the internal combustion engine can be started within a predetermined period, for example, empirically or experimentally or by simulation. May be determined for each alcohol concentration in the fuel and set as a temperature at which the valve timing changes significantly based on the determined relationship.

  It should be noted that when the detected temperature and the temperature threshold value are “equal”, they may be included in either case.

  In another aspect of the start control device for an internal combustion engine of the present invention, the control device further comprises oil viscosity detection means for detecting the viscosity of the engine oil of the internal combustion engine, and the control means further includes the oil viscosity detection means according to the detected viscosity. The valve timing changing means is controlled to change the valve timing.

  According to this aspect, the oil viscosity detecting means detects the viscosity of the engine oil of the internal combustion engine. The viscosity detecting means may detect the viscosity of the engine oil directly by, for example, a sensor, or may detect a physical quantity or parameter having some relationship with the viscosity of the engine oil, such as a friction torque of the crankshaft. Thus, the viscosity of the engine oil may be indirectly detected from the detected physical quantity or parameter.

  The control means further controls the valve timing changing means so as to change the valve timing in accordance with the detected viscosity. The control means typically controls the valve timing changing means so that the valve timing is advanced as the detected concentration is higher and the detected viscosity is lower.

  Therefore, even if the torque required when cranking an internal combustion engine increases due to the viscosity of the engine oil, it is required by reducing the compression reaction force by changing the valve timing. Therefore, the increase in power consumption can be suppressed as a whole, which is very advantageous in practice.

  In another aspect of the start control device for an internal combustion engine of the present invention, the valve timing changing means is a hydraulically driven variable valve mechanism, and the variable valve mechanism is a first hydraulic pressure capable of generating hydraulic pressure by the internal combustion engine. A second hydraulic pump capable of generating the hydraulic pressure by the battery;

  According to this aspect, the valve timing changing means is a hydraulically driven variable valve mechanism. The variable valve mechanism includes a first hydraulic pump capable of generating hydraulic pressure using an internal combustion engine as a drive source, and a second hydraulic pump capable of generating hydraulic pressure using a battery as a drive source (that is, an electric type). .

  According to the inventor's research, a general variable valve mechanism has only a hydraulic pump that uses an internal combustion engine as a drive source. However, since the internal combustion engine is used as a drive source, the rotational speed of the internal combustion engine is low. When the pressure is low (for example, the initial stage of cranking), the hydraulic pressure decreases. Then, it has been found that in the low rotation region, the driving force of the variable valve mechanism may decrease due to a decrease in hydraulic pressure, resulting in an operation delay.

  However, in the present invention, since the electric second hydraulic pump is provided, the internal combustion engine is generated by generating the hydraulic pressure by the second hydraulic pump when the internal combustion engine is started at a relatively low rotational speed. The hydraulic pressure can be appropriately generated without being affected by the number of rotations. Therefore, it is possible to prevent the operation delay of the variable valve mechanism from occurring, which is very advantageous in practice.

  In an aspect in which the valve timing changing means is a variable valve mechanism, the control means may control the second hydraulic pump so as to generate the hydraulic pressure when starting the internal combustion engine.

  If comprised in this way, it can be made comparatively easy and an actual valve timing can be made into a target valve timing, and it is very advantageous practically.

  The operation and other advantages of the present invention will become apparent from the best mode for carrying out the invention described below.

  DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment according to a start control device for an internal combustion engine of the present invention will be described based on the drawings.

<First Embodiment>
A first embodiment of an internal combustion engine start control apparatus according to the present invention will be described with reference to FIGS. FIG. 1 is a block diagram showing the configuration of the start control device according to this embodiment. In addition, the dashed-dotted line in a figure has shown the flow of electric power.

  In FIG. 1, a vehicle on which the start control device 1 according to this embodiment is mounted includes an engine 11, motor generators (MG) 13 and 17, a battery 14, a fuel tank 16, and a power distribution mechanism 18. Yes. Here, the “engine 11” and the “motor / generator 17” according to the present embodiment are examples of the “internal combustion engine” and the “motor” according to the present invention, respectively. The cranking of the engine 11 is typically performed by the motor / generator 17.

  The power distribution mechanism 18 includes a planetary gear mechanism. A planetary carrier rotating shaft 181 of the planetary gear mechanism is connected to a crankshaft of the engine 11. An outer ring gear rotating shaft 182 is a motor generator. 13, and the sun gear rotation shaft 183 is connected to the motor / generator 17. The planetary carrier rotating shaft 181 and the sun gear rotating shaft 183 are coaxially arranged. However, for convenience of explanation, in FIG. 1, the rotating shafts 181 and 183 are arranged on different axes.

  The start control device 1 is included in a variable valve mechanism (VVT) 12 that can change the valve timing of an intake valve (not shown) of the engine 11 and a fuel 161 that contains alcohol stored in a fuel tank 16. A concentration sensor 21 that detects the concentration of alcohol, a remaining charge sensor 22 that detects the remaining charge of the battery 14, a temperature sensor 23 that detects the temperature of the engine 11, and a viscosity that detects the viscosity of the engine oil of the engine 11. The sensor 24 and the ECU 15 that controls the variable valve mechanism 12 so as to change the valve timing according to at least the detected concentration when starting the engine are configured.

  Here, the “variable valve mechanism 12”, the “concentration sensor 21”, the “remaining charge sensor 22”, the “temperature sensor 23”, and the “viscosity sensor 24” according to the present embodiment are the “valve sensor” according to the present invention. It is an example of “timing changing means”, “concentration detection means”, “remaining charge detection means”, “temperature detection means”, and “viscosity detection means”. The “ECU 15” according to the present embodiment is an example of the “control unit”, “valve timing setting unit”, “valve timing correction unit”, and “information storage unit” according to the present invention. In the present embodiment, a part of the ECU 15 for various electronic controls is used as a part of the start control device 1.

  Next, the engine 11 and the variable valve mechanism 12 will be described with reference to FIG. FIG. 2 is a conceptual diagram showing the relationship between the constituent members of the engine and the variable valve mechanism according to this embodiment. In addition, the arrow in a figure has shown the flow of engine oil. For the sake of convenience, the camshaft, cams, valves, etc. on the exhaust side of the engine 11 are not shown.

  In FIG. 2, the engine 11 includes an intake side camshaft 111, a cam 112, an intake valve 113, a piston 114, a crankshaft 115, a crank pulley 116, and an oil pan 117.

  The variable valve mechanism 12 includes a variable valve timing actuator 121, an oil control valve (OCV) 122, an oil pump (OP) 123, and an electric oil pump (EOP) 124. Here, the “oil pump 123” and the “electric oil pump 124” according to the present embodiment are examples of the “first hydraulic pump” and the “second hydraulic pump” according to the present invention, respectively.

  As shown in FIG. 2, a motor / generator 17 is connected to one end of the crankshaft 115 via a power distribution mechanism 18 (not shown), and a crankshaft pulley is connected to the other end of the crankshaft 115. 116 is connected. The crankshaft pulley 116 is connected to the variable valve timing actuator 121 via a timing belt (not shown).

  When the crankshaft 115 is rotated, the intake side camshaft 111 connected to the variable valve timing actuator 121 is rotated, and the cam 112 connected to the intake side camshaft 111 sets the intake valve 113 to a predetermined value. It is opened and closed at the timing.

  The oil control valve 122 guides the engine oil 117a supplied from the oil pump 123 or the electric oil pump 124 connected to the crankshaft 115 to the advance side oil path or the retard side oil path of the variable valve timing actuator 121. Thus, the valve timing of the intake valve 113 can be changed.

  Next, when the vehicle equipped with the start control device 1 configured as described above is started or running (typically, when the engine 11 is started only when the motor / generator 13 is running). The engine start control process executed by the ECU 15 will be described with reference to the flowchart of FIG.

  In FIG. 3, the temperature sensor 23 detects the temperature of the engine 11 (step S <b> 102) after being set to the “ignition ON state” by, for example, pressing an engine start button or the like by the operator (step S <b> 101). The temperature sensor 23 may detect the temperature of the cylinder of the engine 11 or may detect the temperature of cooling water, for example.

  Next, the ECU 15 determines whether or not the detected temperature is higher than a temperature threshold value that is, for example, -20 degrees Celsius (step S103). When it is determined that the detected temperature is higher than the temperature threshold (step S103: Yes), for example, the start control is executed without changing the valve timing of the intake valve 113 or the like (ie, normal) (step S109). ).

  When it is determined that the detected temperature is lower than the temperature threshold (step S103: No), the concentration sensor 21 detects the concentration of alcohol contained in the fuel 161 (step S104). Subsequently, the ECU 15 determines whether or not the detected concentration is higher than a concentration threshold value, for example, 50% (step S105). Note that the “concentration threshold value” is obtained empirically, experimentally, or by simulation, for example, to determine the relationship between the alcohol concentration and the time taken to start the engine 11 when the temperature of the engine 11 is equal to the temperature threshold value. Based on this relationship, the concentration at which the engine 11 cannot be started within a predetermined period, or a concentration lower than the concentration by a predetermined amount may be set.

  When it is determined that the detected density is lower than the density threshold value (step S105: No), normal start control is executed (step S109). On the other hand, when it is determined that the detected concentration is higher than the concentration threshold (step S105: Yes), the ECU 15 sets a target valve timing according to the detected concentration (step S106).

  Here, the setting of the target valve timing will be described with reference to FIGS. FIG. 4 is a characteristic diagram showing an example of the relationship between the concentration of alcohol at -35 degrees Celsius and the time taken to complete explosion for each advance amount of the valve timing, and FIG. It is a characteristic view which shows an example of the relationship with the amount of advance of valve timing for every density | concentration of alcohol.

  Note that the time Ts in FIG. 4 indicates a reference value determined based on the power of the battery 14 consumed until the complete explosion. Also, the solid lines a1, a2, a3 and a4 in FIG. 4 show the relationship between the alcohol concentration and the time taken to complete explosion when the advance amount is 0 degree, 10 degrees, 20 degrees and 30 degrees, respectively. Show. Also, solid lines e1, e2, and e3 in FIG. 5 indicate the environmental temperature and valve timing in the case of a high alcohol concentration (for example, 80%), a medium alcohol concentration (for example, 50%), and a low alcohol concentration (for example, 5%), respectively. It shows the relationship with the required advance amount.

  The ECU 15 stores characteristic diagrams as shown in FIGS. 4 and 5 as a map. For example, the ECU 15 proceeds from the characteristic diagram corresponding to the detected temperature as shown in FIG. 4 according to the detected concentration. The target valve timing is set by specifying the angular amount (advancing amount capable of complete explosion within time Ts). Alternatively, from the characteristic diagram as shown in FIG. 5, the relationship corresponding to the detected concentration is specified, the advance amount corresponding to the detected temperature is specified, and the target valve timing is set.

  As shown in FIG. 4, if the valve timing is not advanced (changed), it can be seen that if the alcohol concentration is higher than a certain alcohol concentration, even if the engine is cranked for a long time, no complete explosion occurs. For this reason, if no measures are taken, there is a risk that, for example, fuel hammer, dilution of engine oil, etc. may occur due to the fuel supplied during cranking.

  However, in this embodiment, as will be described later, the variable valve mechanism 12 is controlled by the ECU 15 so that the valve timing of the intake valve 113 becomes the set target valve timing. That is, the ECU 15 controls the variable valve mechanism 12 so as to change the valve timing in accordance with the detected concentration in order to start the engine 11 within a predetermined period.

  For this reason, it is possible to prevent an unnecessarily long time until the engine 11 is started. As a result, the amount of fuel supplied until the engine 11 is started can be suppressed, and the fuel hammer, engine oil dilution, and the like caused by unburned fuel can be prevented.

  Returning to FIG. 3 again, after the target valve timing is set according to the detected concentration, the ECU 15 controls the motor / generator 17 so as to start cranking of the engine 11 and the electric oil pump 124. Is activated (step S107). Subsequently, the ECU 15 controls the oil control valve 122 so as to guide the engine oil 117a supplied from the electric oil pump 124 to the variable valve timing actuator 121 so that the valve timing of the intake valve 113 becomes the set target valve timing. Is controlled (step S108).

  For example, a fuel injection valve (not shown) is controlled so as to supply the fuel 161 to the engine 11 at the same time as the processing of step S108 or at a time point slightly late, and the supplied fuel 161 is ignited. For example, a distributor (not shown) is controlled.

  Subsequently, the ECU 15 determines whether or not the engine 11 has completely exploded (step S110). When it is determined that the explosion has been completed (step S110: Yes), the process is terminated. On the other hand, if it is determined that the explosion has not been completed (step S110: No), the process of step S110 is repeated until it is determined that the explosion has been completed.

  The ECU 15 according to the present embodiment detects a plurality of types of physical quantities or parameters such as the temperature of the exhaust port and the torque of the motor / generator 17 in addition to the rotational speed of the engine 11, and detects the detected physical quantities or parameters. When any of the parameters exceeds the threshold value, it is determined that the explosion has been completed.

  With such a configuration, it is possible to prevent erroneous determination caused by the motor / generator 17 causing the rotational speed of the engine 11 to be larger than the threshold value in complete explosion determination, which is very advantageous in practice.

  Next, the rotational speed of the engine 11, the advance amount of the valve timing, etc. when the valve timing is changed when starting the engine 11 will be described with reference to FIG. FIG. 6 shows the engine speed, the valve timing advance amount, the signal input to the electric oil pump, and the signal input to the oil control valve when the engine according to this embodiment is started. It is a timing chart which shows a time change. Times T1, T2, and T3 in the figure indicate the time when the ignition is turned on, the time when cranking starts, and the time when complete explosion occurs, respectively.

  As shown in FIG. 6, when the ignition is turned on, a signal indicating that the valve timing is advanced is supplied to the oil control valve 122. When cranking of the engine 11 is started, the power supply of the power oil pump 124 is turned on, and the valve timing is actually advanced.

  As shown in FIG. 6, at the initial stage of cranking of the engine 11, the advance amount is set to be small so that the rotational speed of the engine 11 is likely to increase, and at the stage where the rotational speed becomes relatively high, the engine 11. The amount of advance is such that a compression end temperature capable of starting is obtained. The rotational speed of the engine 11 temporarily decreases as the compression reaction force increases due to an increase in the valve timing advance amount.

  Thereby, the compression end temperature at which the engine 11 can be started quickly can be obtained. As a result, the engine 11 can be started quickly.

  For example, the ECU 15 may be configured to crank the engine 11 (that is, to pre-crank) only for a predetermined period after the ignition is turned on. If comprised in this way, the engine 11 can be warmed up and startability can be improved more.

(First modification)
Next, a first modification of the start control device according to the present embodiment will be described.

  The ECU 15 in the start control device according to the present modification changes the set target valve timing as needed according to the remaining charge of the battery 14 detected by the remaining charge sensor 22 during the process of step S108 in FIG. In addition to correcting, the variable valve mechanism 12 is controlled so that the corrected target valve timing is obtained.

  The ECU 15 typically corrects the target valve timing so that the power consumption per hour is almost constant. Thereby, the power consumption of the battery until the engine 11 is started can be optimized, and it can be prevented that the engine 11 is not started due to power shortage, which is very advantageous in practice.

(Second modification)
Next, a second modification of the start control device according to the present embodiment will be described with reference to FIG. FIG. 7 is an example of a map showing the in-cylinder pressure when the torque output from the motor / generator 17 is constant. Solid lines p1 to p3 in the figure are equal cylinder internal pressure lines.

  In the process of step S106 in FIG. 3, the ECU 15 in the start control device according to this modification first obtains a compression end temperature at which the engine 11 can be started based on the detected alcohol concentration of the fuel 161. Subsequently, the ECU 15 obtains a cylinder pressure at which the obtained compression end temperature can be obtained.

  Next, the ECU 15 specifies an equal cylinder pressure line corresponding to the obtained cylinder pressure from the map as shown in FIG. Subsequently, an advance amount corresponding to a point where the specified equal cylinder internal pressure line and the viscosity of the engine oil 117a detected by the viscosity sensor 24 intersect is specified, and the specified advance amount is determined as a target valve. Set as timing.

  Specifically, for example, when the detected viscosity is large, the advance amount is decreased (that is, the compression reaction force is decreased), and the rotation speed is increased. On the other hand, when the detected viscosity is small, the advance amount is increased to reduce the rotational speed.

  Since the map shown in FIG. 7 is configured such that the torque output from the motor / generator 17 is constant (that is, the power consumption per unit time is constant), the advance angle is set on the map. As long as the amount and the number of revolutions are changed, the power consumption per unit time does not change. Therefore, the power consumption can be suppressed, which is very advantageous in practice.

  When the viscosity of the engine oil 117a changes due to, for example, frictional heat caused by the rotation of the engine 11, the ECU 15 may reset the target valve timing according to the changed viscosity.

Second Embodiment
A second embodiment of the start control device for an internal combustion engine according to the present invention will be described with reference to FIGS. The second embodiment is the same as the configuration of the first embodiment except that the start control process executed by the ECU is partially different. Therefore, in the second embodiment, the description overlapping with that of the first embodiment is omitted, and the common portions on the drawings are denoted by the same reference numerals, and only FIGS. 8 and 9 are basically different only. The description will be given with reference. FIG. 8 is a flowchart showing a start control process executed by the ECU according to this embodiment. FIG. 9 is a data table as an example of “accumulated information” according to the present invention stored in the ECU. It is a conceptual diagram which shows an example.

  In FIG. 8, the ECU 15 in the start control device according to the present embodiment is detected after it is determined that the concentration of alcohol contained in the fuel 161 detected by the concentration sensor 21 is higher than the concentration threshold (step S105: Yes). It is determined whether or not a data table 201 as shown in FIG. 9 corresponding to the density is stored (step S201).

  If it is determined that it is not stored (step S201: No), the ECU 15 subsequently executes the process of step S106. On the other hand, when it is determined that the engine is stored (step S201: Yes), the ECU 15 determines from the data table 201 corresponding to the detected concentration that the valve timing with the shortest time until the engine 11 completes explosion (see FIG. The “advance amount” is specified, and the specified valve timing is set as the target valve timing (step S202).

  In addition to the detected concentration, the ECU 15 includes, among data corresponding to a plurality of physical quantities or parameters such as the temperature of the engine 11, the environmental temperature, the viscosity of the engine oil 117a, the remaining charge of the battery 14, and the like. The target valve timing may be set by specifying the valve timing with the shortest time until the complete explosion. In this way, a more appropriate target valve timing can be set.

  The data table 201 as shown in FIG. 9 includes physical quantities or parameters detected by the ECU 15 through various sensors each time the engine 11 is started (that is, every time the start control process is executed). It is created by storing the set target valve timing or the like in, for example, a nonvolatile memory or the like.

  It should be noted that the present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist or concept of the invention that can be read from the claims and the entire specification. An engine start control device is also included in the technical scope of the present invention.

It is a block diagram which shows the structure of the starting control apparatus which concerns on 1st Embodiment. It is a conceptual diagram which shows the relationship of each structural member of the engine which concerns on 1st Embodiment, and a variable valve mechanism. It is a flowchart which shows the starting control process which ECU which concerns on 1st Embodiment performs. It is a characteristic view which shows an example of the relationship between the concentration of alcohol at -35 degrees Celsius and the time taken to complete explosion for each advance amount of valve timing. It is a characteristic view which shows an example of the relationship between environmental temperature and the advance amount of valve timing for every density | concentration of alcohol. Timing chart showing changes over time in engine speed, advance amount of valve timing, signal input to electric oil pump, and signal input to oil control valve when starting engine according to the first embodiment It is. It is an example of the map which shows the pressure in a cylinder in case the torque output from a motor generator is constant. It is a flowchart which shows the starting control process which ECU which concerns on 2nd Embodiment performs. It is a conceptual diagram which shows an example of the data table stored in ECU which concerns on 2nd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Start-up control apparatus, 11 ... Engine, 12 ... Variable valve mechanism, 13, 17 ... Motor generator, 14 ... Battery, 15 ... ECU, 16 ... Fuel tank, 18 ... Power distribution mechanism, 21 ... Concentration sensor, 22 ... Remaining charge sensor, 23 ... Temperature sensor, 24 ... Viscosity sensor, 111 ... Intake camshaft, 112 ... Cam, 113 ... Intake valve, 114 ... Piston, 115 ... Crankshaft, 116 ... Crank pulley, 117 ... Oil pan, 121 ... Variable valve timing actuator, 122 ... Oil control valve, 123 ... Oil pump, 124 ... Electric oil pump, 201 ... Data table

Claims (9)

Start of the internal combustion engine in a vehicle comprising an internal combustion engine capable of using a fuel containing alcohol, a motor for rotating the internal combustion engine at least until the internal combustion engine is started, and a battery for supplying electric power to the motor A control device,
Valve timing changing means capable of changing the valve timing of the intake valve of the internal combustion engine;
Alcohol concentration detection means for detecting the concentration of alcohol contained in the fuel;
And a control means for controlling the valve timing changing means so as to change the valve timing in accordance with the detected concentration when starting the internal combustion engine. . The control means includes
Valve timing setting means for setting a target valve timing as a target of the valve timing according to the detected concentration;
The start control device for an internal combustion engine according to claim 1, wherein the valve timing changing means is controlled so that the valve timing becomes the set target valve timing. It further comprises information storage means for storing information relating to the internal combustion engine until the internal combustion engine is started,
The start of the internal combustion engine according to claim 2, wherein the valve timing setting means specifies the information corresponding to the detected concentration from the accumulated information and sets the target valve timing. Control device. When the internal combustion engine is rotated by the motor, the remaining charge detection means for detecting the remaining charge of the battery;
Valve timing correction means for correcting the set target valve timing according to the detected remaining charge,
The control means controls the motor so that torque according to the detected remaining charge level is output, and the valve timing changing means so that the valve timing becomes the corrected target valve timing. The start control device for an internal combustion engine according to claim 2 or 3, wherein   5. The control unit according to claim 1, wherein the control unit controls the valve timing changing unit such that the valve timing is advanced as the detected concentration is higher. 6. A start control device for an internal combustion engine. Temperature detecting means for detecting the temperature of the internal combustion engine,
The control means controls the valve timing changing means to change the valve timing in accordance with the detected concentration, on condition that the detected temperature is lower than a temperature threshold value. The start control device for an internal combustion engine according to any one of claims 1 to 5. An oil viscosity detecting means for detecting the viscosity of the engine oil of the internal combustion engine;
The internal combustion engine according to any one of claims 1 to 6, wherein the control means further controls the valve timing changing means to change the valve timing in accordance with the detected viscosity. Engine start control device. The valve timing changing means is a hydraulically driven variable valve mechanism,
The variable valve mechanism is
A first hydraulic pump capable of generating hydraulic pressure by the internal combustion engine;
The internal combustion engine start control device according to any one of claims 1 to 7, further comprising: a second hydraulic pump capable of generating the hydraulic pressure by the battery.   9. The start control device for an internal combustion engine according to claim 8, wherein the control means controls the second hydraulic pump so as to generate the hydraulic pressure when starting the internal combustion engine.

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