JP4419800B2 - Engine starter - Google Patents

Description

  The present invention relates to an engine starter that starts an engine without using a starter motor.

  In recent years, as a method for measures against exhaust gas and improving fuel efficiency, there has been a technology in which the engine is automatically stopped when the vehicle is stopped in an idle state, and is automatically restarted when starting to smoothly start. Various proposals have been made. In this case, if it takes a long time to restart the engine, a response is delayed with respect to the driver's intention to start, and drivability deteriorates. Therefore, it is important to restart the engine quickly. However, when starting an engine, a starter motor is generally used. By frequently stopping and starting the engine, the life of the starter motor and peripheral parts is reduced, and the charge amount is reduced due to excessive use of the battery. Will be invited.

  Therefore, for example, in Patent Document 1 described below, an in-cylinder injection engine that directly injects fuel into a combustion chamber instead of an intake port can start the engine without using a starter. The “engine starter” described in Patent Document 1 is an in-cylinder injection engine, and when the engine is restarted, the closing timing of the intake valve of the cylinder in the compression stroke is retarded and the expansion stroke is in progress. A predetermined amount of fuel is injected into the cylinder and burned by igniting the air-fuel mixture in the cylinder, and the piston is pushed down by the generated expansion force to self-start.

JP 2002-39038 A

  In the above-described conventional “engine starter”, the closing timing of the intake valve of the cylinder in the compression stroke is retarded, while fuel is injected and ignited in the cylinder in the expansion stroke, and the piston is generated by the generated expansion force. The self-starting operation is facilitated by reducing the compression force of the cylinder in the compression stroke. In this case, a valve timing phase varying mechanism for controlling the opening / closing timing of the intake valve is used as means for retarding the closing timing of the intake valve of the cylinder in the compression stroke.

  FIG. 11 is a schematic diagram showing opening and closing timings of an intake valve and an exhaust valve in a conventional engine starter, and FIG. 12 is a graph showing in-cylinder pressure with respect to a crank angle.

  That is, when the valve timing phase variable mechanism is used and the closing timing of the intake valve is delayed as in the conventional “engine starter”, the opening timing is also delayed. That is, as shown in FIG. 11, the opening / closing timing of the intake valve is retarded from the period indicated by the two-dot chain line to the period indicated by the solid line, and the exhaust valve closing timing (EX closing) and the intake valve opening timing (IN A cylinder sealing period in which the cylinder is in a sealed state occurs during the opening. Then, since the piston descends during the cylinder sealing period, the inside of the cylinder is in a negative pressure state, and as shown in FIG. 12, a pump loss occurs due to the piston, and the driving torque necessary to start the engine increases. There is a problem that the startability is lowered.

  The present invention is intended to solve such a problem, and provides an engine starter capable of reliably starting an engine without using a starter motor and improving startability. With the goal.

  In order to solve the above-described problems and achieve the object, an engine starter according to the present invention includes a combustion chamber, an intake port and an exhaust port communicating with the combustion chamber, and an intake port that opens and closes the intake port and the exhaust port. A valve and an exhaust valve; fuel injection means for injecting fuel into the combustion chamber; ignition means for igniting an air-fuel mixture in the combustion chamber; crank angle detection means for detecting a crank angle of the engine; and closing of the exhaust valve Variable valve means capable of changing the closing timing of the intake valve while ensuring an overlap between the opening timing and the opening timing of the intake valve, and delaying the closing timing of the intake valve by the variable valve means before starting On the other hand, on the basis of the detection result of the crank angle detecting means, fuel injection is performed by the fuel injection means at the start of the cylinder in the expansion stroke, and ignition is performed by the ignition means. It is characterized in that and control means for the line.

  In the engine starter according to the present invention, the control means may be arranged such that the variable valve means delays the closing timing of the intake valve with respect to the cylinder that is in the compression stroke when the engine is started, and then the cylinder is in the expansion stroke. On the other hand, the fuel injection and the ignition are executed.

  In the engine starting device of the present invention, the control means retards the closing timing of the intake valve by the variable valve means with respect to the cylinder that is in the compression stroke when the engine is stopped, and the cylinder is in the expansion stroke when the engine is started. On the other hand, the fuel injection and the ignition are executed.

  In the engine starting device of the present invention, the variable valve operating means retards the opening timing of the exhaust valve while ensuring an overlap between the closing timing of the exhaust valve and the opening timing of the intake valve, and the intake valve. It is characterized by delaying the closing time.

  In the engine starter according to the present invention, the variable valve means delays the opening / closing timing of the intake valve and the opening / closing timing of the exhaust valve by substantially the same amount without changing the opening period of the intake valve and the exhaust valve. It is characterized by doing.

  In the engine starting device of the present invention, the variable valve operating means delays only the closing timing of the intake valve by extending the opening period of the intake valve.

In the engine starter according to the present invention, the variable valve operating means delays only the opening timing of the exhaust valve by extending the opening period of the exhaust valve.
In the engine starting device of the present invention, the variable valve operating means delays the closing timing of the intake valve while setting an overlap between the closing timing of the exhaust valve and the opening timing of the intake valve as a 0 degree crank angle. It is characterized by.

  According to the engine starter of the present invention, the fuel injection means for injecting fuel into the combustion chamber, the ignition means for igniting the air-fuel mixture in the combustion chamber, the crank angle detection means for detecting the crank angle of the engine, and the exhaust valve Variable valve means that can change the closing timing of the intake valve while ensuring an overlap between the closing timing of the intake valve and the opening timing of the intake valve is provided, and the control means delays the closing timing of the intake valve before starting On the other hand, since fuel injection and ignition are performed for the cylinder in the expansion stroke at the time of starting, when the engine is started, the closing timing of the intake valve is delayed and the cylinder in the expansion stroke is On the other hand, fuel injection and ignition are executed, and in the cylinder in the expansion stroke, the piston is reliably lowered by the torque generated by the explosion, while in the cylinder in the compression stroke, the pressure is reduced. Because the force decreases, this torque can easily raise the piston, and at this time, the overlap between the exhaust valve closing timing and the intake valve opening timing is secured, so the negative pressure in the cylinder The pump loss due to the engine is suppressed, the increase in driving torque necessary for starting the engine is suppressed, the engine can be started reliably without using the starter motor, and the startability of the engine can be improved.

  Embodiments of an engine starter according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

  1 is a schematic configuration diagram showing an engine starter according to Embodiment 1 of the present invention, FIG. 2 is a flowchart showing engine control in the engine starter of Embodiment 1, and FIG. 3 is an in-cylinder behavior when the engine is stopped. FIG. 4 is a schematic diagram showing the opening and closing timing of the intake valve and the exhaust valve, FIG. 5 is a graph showing changes in the cylinder pressure and crank angle of the # 1 cylinder and # 3 cylinder, and FIG. It is a graph showing the in-cylinder pressure with respect to a crank angle.

  In the engine to which the engine starter of the first embodiment is applied, as shown in FIG. 1, the engine 10 is a cylinder injection type four-cylinder in-line engine. In this engine 10, a cylinder head 12 is fastened on a cylinder block 11, and pistons 14 are fitted to a plurality of cylinder bores 13 formed in the cylinder block 11 so as to freely move up and down. A crankcase 15 is fastened to the lower part of the cylinder block 11, and a crankshaft 16 is rotatably supported in the crankcase 15. Each piston 14 is connected to the crankshaft 16 via a connecting rod 17. Has been.

  The combustion chamber 18 includes a cylinder block 11, a cylinder head 12, and a piston 14, and the combustion chamber 18 has a pent roof shape that is inclined so that the central portion of the upper portion (the lower surface of the cylinder head 12) is raised. Yes. An intake port 19 and an exhaust port 20 are formed on the upper portion of the combustion chamber 18, that is, the lower surface of the cylinder head 12, and the intake valve 19 and the exhaust valve 20 are opposed to the intake port 19 and the exhaust port 20. The lower end portions of 22 are respectively positioned. The intake valve 21 and the exhaust valve 22 are supported by the cylinder head 12 so as to be movable in the axial direction, and are urged and supported in a direction to close the intake port 19 and the exhaust port 20. An intake camshaft 23 and an exhaust camshaft 24 are rotatably supported by the cylinder head 12, and the intake cam 25 and the exhaust cam 26 are connected to upper ends of the intake valve 21 and the exhaust valve 22 via a roller rocker arm (not shown). In contact with the part.

  Therefore, when the intake camshaft 23 and the exhaust camshaft 24 rotate in synchronization with the engine 10, the intake cam 25 and the exhaust cam 26 operate the roller rocker arm, and the intake valve 21 and the exhaust valve 22 move up and down at a predetermined timing. Thus, the intake port 19 and the exhaust port 20 can be opened and closed, and the intake port 19 and the combustion chamber 18 can be communicated with each other.

  Further, the valve mechanism of the engine 10 is a variable valve timing-intelligent (VVT) mechanism 27 or 28 that controls the intake valve 21 and the exhaust valve 22 at an optimal opening / closing timing according to the operating state. It has become. The intake / exhaust variable valve mechanisms 27, 28 are configured, for example, by providing a VVT controller at the shaft ends of the intake camshaft 23 and the exhaust camshaft 24, and a cam for the cam sprocket by an electric motor (or hydraulic pump). The opening / closing timing of the intake valve 21 and the exhaust valve 22 can be advanced or retarded by changing the phase with the shaft. In this case, the intake / exhaust variable valve operating mechanisms 27, 28 advance or retard the opening / closing timing while keeping the operating angle (opening period) of the intake valve 21 and the exhaust valve 22 constant. The intake camshaft 23 and the exhaust camshaft 24 are provided with cam position sensors 29 and 30 for detecting the rotational phase.

  A surge tank 32 is connected to the intake port 19 via an intake manifold 31, and an intake pipe 33 is connected to the surge tank 32, and an air cleaner 34 is attached to an air intake port of the intake pipe 33. . An electronic throttle device 36 having a throttle valve 35 is provided on the downstream side of the air cleaner 34. Further, the cylinder head 12 is provided with an injector (fuel injection means) 37 for directly injecting fuel into the combustion chamber 18, and this injector 37 is located on the intake port 19 side and is inclined at a predetermined angle in the vertical direction. ing. Further, a spark plug (ignition means) 38 that is positioned above the combustion chamber 18 and ignites the air-fuel mixture is mounted on the cylinder head 12.

  On the other hand, an exhaust pipe 40 is connected to the exhaust port 20 via an exhaust manifold 39. The exhaust pipe 40 is a catalyst device for purifying harmful substances such as HC, CO, NOx contained in the exhaust gas. 41 is attached.

  Incidentally, an electronic control unit (ECU) 42 is mounted on the vehicle, and the ECU 42 can control the injector 37, the spark plug 38, and the like. That is, an air flow sensor 43 is mounted on the upstream side of the intake pipe 33, and the measured intake air amount is output to the ECU. Further, the electronic throttle device 36 outputs the current throttle opening to the ECU 42. Further, the crank angle sensor (crank angle detecting means) 44 outputs the detected crank angle of each cylinder to the ECU 42, and the ECU 42 performs intake, compression, expansion (explosion), exhaust in each cylinder based on the detected crank angle. And determining the engine speed. The cylinder head 12 is provided with a water temperature sensor 45 that detects the engine cooling water temperature, and outputs the detected engine cooling water temperature to the ECU 42. Therefore, the ECU 42 determines the fuel injection amount, the injection timing, the ignition timing, and the like based on the detected intake air amount, throttle opening (or accelerator opening), engine speed, engine cooling water temperature, and other engine operating conditions. ing.

  Further, the ECU 42 can control the intake / exhaust variable valve mechanisms 27 and 28 based on the engine operating state. That is, when the temperature is low, the engine is started, the engine is idle, or the load is light, the exhaust gas blows back into the intake port 19 or the combustion chamber 18 by eliminating the overlap between the exhaust valve 22 closing timing and the intake valve 21 opening timing. Reduce the amount to enable stable combustion and improved fuel efficiency. Further, at the time of medium load, by increasing the overlap, the internal EGR rate is increased to improve the exhaust gas purification efficiency, and the pumping loss is reduced to improve the fuel consumption. Further, at the time of high-load low-medium rotation, the closing timing of the intake valve 21 is advanced, thereby reducing the amount of intake air that blows back to the intake port 19 and improving the volume efficiency. At the time of high load and high rotation, the closing timing of the intake valve 21 is retarded in accordance with the rotation speed, so that the timing is adjusted to the inertial force of the intake air and the volume efficiency is improved.

  The engine 10 configured as described above is automatically restarted by an engine automatic stop function for automatically stopping the engine when the vehicle is stopped in an idle state and a start command when the engine is automatically stopped. It has an engine restart function for starting. In this embodiment, when the engine 10 is restarted, the engine 10 is ignited using the in-cylinder injection mechanism without using the starter motor.

  That is, the ECU 42 as the control means determines the cylinder stopped in the expansion stroke based on the detection result of the crank angle sensor 44 after the engine 10 is stopped, and stops in this expansion stroke when the engine 10 is restarted. Fuel is injected into the cylinders that are in operation, and the mixture is ignited to obtain an explosive force to drive the crankshaft 16 through the piston 14 and restart the engine 10. In the case of the present embodiment, since it is the in-cylinder injection type four-cylinder in-line engine 10, for example, as shown in FIG. 3, the first cylinder # 1 stops at the expansion stroke beyond the top dead center (TDC). At that time, the following third cylinder # 3 stops in the compression stroke. Then, fuel is injected into the first cylinder # 1 stopped in the expansion stroke to start ignition, the piston 14 is pushed down by the explosive force of the first cylinder # 1, and the third cylinder # 1 is connected via the crankshaft 16. 3 piston 14 is pushed up. In this case, in the third cylinder # 3 in the compression stroke, the piston 14 ascends and obtains the force for compressing the air in the combustion chamber 18 from the explosive force of the first cylinder # 1, so the first cylinder # 1 It is desirable to stop in the latter half of the expansion stroke exceeding TDC, and in the third cylinder # 3, stop in the latter half of the compression stroke exceeding BTDC.

  In this embodiment, the intake / exhaust variable valve mechanisms 27 and 28 can be controlled based on the engine operating state. As shown in FIGS. 3 and 4, when the engine 10 is restarted, Thus, the closing timing of the intake valve 21 is retarded while ensuring the overlap between the closing timing of the exhaust valve 22 and the opening timing of the intake valve 21 at a crank angle of 0 ° or more. That is, as described above, when the crankshaft 16 is rotated via the piston 14 by the explosive force of the first cylinder # 1 in the expansion stroke, if the intake valve 21 is closed, the combustion chamber 18 is sealed and compressed. In the third cylinder # 3 in the stroke, the piston 14 cannot be sufficiently raised, and the restart of the engine 10 is hindered. Therefore, when the engine 10 is restarted, the intake variable valve mechanism 27 is controlled, and the closing timing of the intake valve 21 is retarded from the idle region indicated by the two-dot chain line in FIG. 4 to the restart region indicated by the solid line. Thus, the period during which the combustion chamber 18 is sealed is shortened, and the piston 14 is properly raised in the third cylinder # 3 in the compression stroke, so that the engine 10 can be reliably restarted.

  The intake variable valve mechanism 27 changes the opening / closing timing of the intake valve 21. If the closing timing of the intake valve 21 is retarded, the opening timing is retarded, and the closing timing of the exhaust valve 22 and the intake timing are retarded. The overlap region at the opening timing of the valve 21 disappears, and the combustion chamber 18 is in a sealed state from when the exhaust valve 22 is closed until the intake valve 21 is opened. If the piston 14 descends during this sealing period, the combustion chamber 18 is in a negative pressure state, and a pump loss due to the piston 14 occurs. Therefore, when the engine 10 is restarted, the opening / closing timing of the intake valve 21 is retarded by the intake variable valve mechanism 27, and the opening / closing timing of the exhaust valve 22 by the exhaust variable valve mechanism 28 is indicated by a two-dot chain line in FIG. The overlap region between the closing timing of the exhaust valve 22 and the opening timing of the intake valve 21 is secured by retarding the same amount as the intake valve 21 from the indicated idle region to the restart region represented by the solid line. For this reason, there is no period in which the combustion chamber 18 is in a sealed state, and generation of pump loss by the piston 14 is prevented.

  Further, by delaying the opening / closing timing of the exhaust valve 22 by the exhaust variable valve mechanism 28, the opening timing of the exhaust valve 22 is delayed, so that the first cylinder # 1 in the expansion stroke when the engine 10 is restarted. Then, while the piston 14 is descending, the exhaust valve 22 is in a closed state to prevent a rapid decrease in the combustion pressure during the expansion stroke.

  Here, the operation control of the engine starting device of the first embodiment will be described in detail based on the flowchart of FIG.

  As shown in FIGS. 1 and 2, in step S <b> 1, it is determined whether an automatic stop condition for the engine 10 is satisfied during operation of the vehicle. Here, the automatic stop of the engine 10 is a so-called idle stop in which the engine is stopped during idle operation. For example, the automatic stop condition of the engine 10 is a vehicle speed of 0 km / h, a brake switch being in an ON state, That the operation position of the shift lever is in the neutral (N) position has continued for a predetermined time. At this time, it is determined that the vehicle is stopped by a red light and it is determined that the automatic stop condition is satisfied. The engine 10 may be stopped while the vehicle is decelerating. In this case, the automatic stop condition of the engine 10 is that the vehicle speed is a constant speed or less, the engine speed is a constant speed or less, the engine coolant temperature is a constant temperature or less, The air conditioner is in the OFF state. At this time, it is determined that the vehicle is decelerating and it is determined that the automatic stop condition is satisfied.

  If it is determined in step S1 that the automatic stop condition of the engine 10 is satisfied, the process proceeds to step S2, where fuel injection by the injector 37 is stopped and ignition by the spark plug 38 is stopped.

  In step S3, it is determined whether an engine restart condition is satisfied in a state where the engine 10 is automatically stopped. Here, the restart condition of the engine 10 is, for example, when the vehicle speed is 0 km / h, the brake switch is ON, and the shift lever is operated at the travel (1, 2, D, R) position. It is determined that there is an intention to start, and it is determined that the restart condition is satisfied. If it is determined in step S3 that the restart condition of the engine 10 is satisfied, the process proceeds to step S4 and preparation for starting the engine 10 is started.

  That is, in step S4, the ECU 42 controls the intake / exhaust variable valve operating mechanisms 27, 28 to retard the opening / closing timing of the intake valve 21 and the exhaust valve 22 by a predetermined amount. In this case, by setting the retard amount of the intake valve 21 and the exhaust valve 22 to the same amount, an overlap between the closing timing of the exhaust valve 22 and the opening timing of the intake valve 21 is ensured. In step S5, when the engine 10 is automatically stopped, the cylinder stopped in the expansion stroke is determined based on the detection result of the crank angle sensor 44, and the combustion chamber 18 of the cylinder stopped in the expansion stroke is determined. On the other hand, a predetermined amount of fuel is injected by the injector 37, and the air-fuel mixture is ignited by the spark plug 38, whereby this cylinder obtains explosive force and lowers the piston 14.

  When the cylinder stopped in the expansion stroke explodes and the piston 14 is lowered, the crankshaft 16 is rotated, and this rotational force is stopped in the cylinder following the cylinder stopped in the expansion stroke, that is, in the compression stroke. The piston 14 is raised and the compression stroke is started. Similarly, a predetermined amount of fuel is injected into the cylinder by the injector 37, and the air-fuel mixture is ignited by the spark plug 38, whereby the cylinder obtains explosive force and lowers the piston 14. Further, for the cylinders following the cylinders stopped in this compression stroke, air is sucked from the intake port 19 as usual, a predetermined amount of fuel is injected from the injector 37, and the air-fuel mixture is made into an air-fuel mixture by the spark plug 38. By igniting, the explosive force is obtained and the piston 14 is lowered, and when the explosive force continues for a predetermined time, the crankshaft 16 is driven and the engine 10 is restarted.

  Here, the engine behavior at this time will be described in detail. As shown in FIG. 3, in the cylinder stopped in the expansion stroke, a predetermined amount of fuel is injected with respect to the remaining amount of air (oxygen), and an appropriate mixture is ignited to explode. Obtaining force, the piston 14 is lowered and the crankshaft 16 is rotated. The rotational force of the crankshaft 16 is transmitted to the cylinder following the cylinder stopped in the expansion stroke, that is, the cylinder stopped in the compression stroke, and the piston 14 of this cylinder is raised. At this time, in the cylinder stopped in the expansion stroke, since the opening timing of the exhaust valve 22 is retarded, the sealed state in the combustion chamber 18 is continued for a long time, and a rapid decrease in the combustion pressure is suppressed. Accordingly, the expansion force by the combustion gas is promoted, and the crankshaft 16 can be efficiently rotated. Further, in the cylinder stopped in the compression stroke, since the closing timing of the intake valve 21 is retarded, the open state in the combustion chamber 18 is continued for a long time, and a rapid increase in the in-cylinder pressure is suppressed. The in-cylinder pressure does not become a large resistance that raises the piston 14, and the compression stroke can be reliably completed by the expansion force of the cylinder stopped in the expansion stroke.

  That is, as shown in FIG. 5, when the engine 10 is restarted, the in-cylinder pressure rises to a predetermined pressure due to the expansion of the first cylinder # 1 that is stopped in the expansion stroke, and the exhaust valve 22 is opened to exhaust the exhaust. By shifting to the stroke, the in-cylinder pressure gradually decreases. At this time, since the valve opening timing of the exhaust valve 22 is retarded, a rapid decrease in the in-cylinder pressure as shown by the two-dot chain line in the figure is suppressed, and the in-cylinder pressure gradually increases as shown by the solid line in the figure. descend. Further, the in-cylinder pressure gradually rises to a predetermined pressure due to the compression of the third cylinder # 3 stopped in the compression stroke, and the in-cylinder pressure rapidly rises by closing the intake valve 21 and shifting to the expansion stroke. . At this time, since the closing timing of the intake valve 21 is retarded, an increase in the in-cylinder pressure in the compression stroke as shown by a two-dot chain line in the same figure is suppressed, and the in-cylinder pressure decreases as shown by a solid line in the figure. To do. Therefore, when the third cylinder # 3 exceeds the TDC and rotates the crankshaft 16 following the first cylinder # 1, the engine 10 is started properly.

  At this time, even if the opening / closing timing of the intake valve 21 and the exhaust valve 22 is retarded, an overlap between the closing timing of the exhaust valve 22 and the opening timing of the intake valve 21 is ensured. The period during which the combustion chamber 18 is in a sealed state is eliminated, and generation of pump loss due to the piston 14 can be prevented. That is, as shown in FIG. 6, when the transition is made from the exhaust stroke to the intake stroke, the opening timing of the intake valve 21 and the exhaust valve 22 overlaps, so that the in-cylinder pressure decreases as shown by the two-dot chain line in FIG. The pumping loss due to is suppressed, and the in-cylinder pressure is maintained constant as shown by the solid line in FIG.

  Thereafter, returning to FIG. 2, in step S6, it is determined whether or not the ignition start of the engine 10 is completed. If the ignition start cannot be performed, the engine 10 is started by the starter motor in step S7. When the engine 10 is restarted by ignition start or starter motor start, in step S8, the ECU 42 controls the intake / exhaust variable valve mechanisms 27, 28, thereby controlling the intake valve 21 and the exhaust valve 22. Return the opening / closing timing to the normal position.

  As described above, in the engine starter according to the first embodiment, the injector 37 that directly injects fuel into the combustion chamber 18 and the spark plug 38 that ignites the air-fuel mixture in the combustion chamber 18 are provided, and the crank angle of the engine 10 is detected. The crank angle sensor 44, the intake valve 21 and the exhaust valve 22 that can change the opening / closing timing of the intake / exhaust valve 22 are provided. The ECU 42 performs exhaust when an engine 10 restart command is input. While ensuring the overlap between the closing timing of the valve 22 and the opening timing of the intake valve 21, the opening / closing timing of the intake valve 21 and the exhaust valve 22 is retarded while the cylinder in the expansion stroke detected by the crank angle sensor 41 is used. Thus, fuel injection is performed and ignition is performed.

  Therefore, in the cylinder stopped in the expansion stroke, the valve opening timing of the exhaust valve 22 is retarded, and the sealed state of the combustion chamber 18 is continued for a long time, and a rapid decrease in the combustion pressure is suppressed and the combustion gas is suppressed. The crankshaft 16 can be efficiently rotated by promoting the expansion force due to. Further, in the cylinder stopped in the compression stroke, the closing timing of the intake valve 21 is delayed and the open state in the combustion chamber 18 is continued for a long time, and the increase in the in-cylinder pressure is suppressed and the piston 14 is raised. Therefore, the compression stroke can be reliably completed by the expansion force of the cylinder stopped in the expansion stroke. Furthermore, even if the opening / closing timing of the intake valve 21 and the exhaust valve 22 is retarded, an overlap between the closing timing of the exhaust valve 22 and the opening timing of the intake valve 21 is ensured, so that the exhaust stroke is changed to the intake stroke. Generation of pump loss due to the piston 14 can be prevented during the transition. As a result, when the engine 10 is restarted, fuel is injected and ignited in the combustion chamber 18 of the cylinder stopped in the compression stroke following the cylinder stopped in the expansion stroke, thereby ensuring an appropriate explosive force. The engine 10 can be reliably started without using the starter motor.

  FIG. 7 is a schematic configuration diagram showing an engine starter according to Embodiment 2 of the present invention, and FIG. 8 is a schematic view showing opening / closing timings of intake valves and exhaust valves in the engine starter of Embodiment 2. In addition, the same code | symbol is attached | subjected to the member which has the same function as what was demonstrated in the Example mentioned above, and the overlapping description is abbreviate | omitted.

  In the engine starter of the second embodiment, as shown in FIG. 7, the valve mechanism of the engine 10 is an intake variable valve mechanism 51 that controls the intake valve 21 at an optimal opening / closing timing according to the operating state. . The intake variable valve mechanism 51 has, for example, a second intake cam (not shown) provided adjacent to each intake cam 25 of the intake camshaft 23, and moves the intake camshaft 23 in the axial direction so that the intake cam By switching between 25 and the second intake cam, the operating angle of the intake valve 21 can be changed to increase or decrease the lift amount, and the closing timing can be advanced or retarded.

  The ECU 42 can control the intake variable valve mechanism 51 based on the engine operating state. As shown in FIG. 8, when the engine 10 is restarted, the exhaust valve 22 is closed when the engine 10 is idle. In addition, the closing timing of the intake valve 21 is delayed while the overlap of the opening timing of the intake valve 21 is ensured to be 0 degree crank angle or more. That is, when the engine 10 is restarted, the intake variable valve mechanism 51 is controlled, and the closing timing of the intake valve 21 is retarded from the idle region indicated by the two-dot chain line in FIG. 8 to the restart region indicated by the solid line. Thus, the period during which the combustion chamber 18 is sealed is shortened, and the piston 14 is properly raised in the cylinder in the compression stroke so that the engine 10 can be reliably restarted. At this time, since the opening timing of the intake valve 21 is not changed, an overlap region between the closing timing of the exhaust valve 22 and the opening timing of the intake valve 21 is secured, and there is no period in which the combustion chamber 18 is in a sealed state. Generation of pump loss is prevented.

  Accordingly, as shown in FIGS. 7 and 8, when the automatic stop condition of the engine 10 is satisfied, the fuel injection by the injector 37 is stopped, the ignition by the spark plug 38 is stopped, and the engine 10 is automatically stopped. If the engine restart condition is satisfied in this state, the ECU 42 controls the intake variable valve mechanism 51 to retard the operating angle of the intake valve 21, that is, the closing timing by a predetermined amount. A predetermined amount of fuel is injected by the injector 37 into the combustion chamber 18 of the cylinder stopped in the expansion stroke, and the air-fuel mixture is ignited by the spark plug 38.

  Then, when the cylinder stopped in the expansion stroke explodes and the piston 14 is lowered, the crankshaft 16 is rotated, and this rotational force stops in the compression stroke, that is, the cylinder following the cylinder stopped in the expansion stroke. The piston 14 is raised and the compression stroke is started. At this time, in the cylinder stopped in the compression stroke, the closing timing of the intake valve 21 is retarded, so that the open state in the combustion chamber 18 is continued for a long time, and the rapid increase in the in-cylinder pressure is suppressed. Therefore, the in-cylinder pressure does not become a large resistance that raises the piston 14, and the compression stroke can be reliably completed by the expansion force of the cylinder stopped in the expansion stroke. Similarly, a predetermined amount of fuel is injected into the cylinder by the injector 37, and the air-fuel mixture is ignited by the spark plug 38, whereby the cylinder obtains explosive force and lowers the piston 14. At this time, even if the closing timing of the intake valve 21 is retarded, the opening timing of the intake valve 21 is not retarded, so that an overlap with the closing timing of the exhaust valve 22 is ensured, and the combustion chamber 18 There is no period in which the airtight state is maintained, and generation of pump loss due to the piston 14 can be prevented.

  Thereafter, air is sucked from the intake port 19 in a normal manner to the cylinder following the cylinder stopped in the compression stroke, a predetermined amount of fuel is injected from the injector 37, and the air-fuel mixture is ignited by the spark plug 38. Thus, the explosion force is obtained and the piston 14 is lowered, and the crankshaft 16 is driven and the engine 10 is restarted by continuing the explosion force for a predetermined time.

  Thus, in the engine starter of the second embodiment, the intake variable valve mechanism 51 that can change the operating angle and the closing timing of the intake valve 21 is provided, and the ECU 42 receives a restart command for the engine 10. Sometimes, while ensuring the overlap between the closing timing of the exhaust valve 22 and the opening timing of the intake valve 21, the closing timing of the intake valve 21 is retarded while the cylinder in the expansion stroke detected by the crank angle sensor 41 is used. Thus, fuel injection is performed and ignition is performed.

  Therefore, in the cylinder stopped in the expansion stroke, the explosion is properly generated and the crankshaft 16 can be rotated. In the cylinder stopped in the compression stroke, the closing timing of the intake valve 21 is retarded. The open state in the combustion chamber 18 is continued for a long time, and the increase in the in-cylinder pressure is suppressed, so that there is no large resistance for raising the piston 14, and the expansion force of the cylinder stopped in the expansion stroke is ensured. The compression stroke can be completed. Even if the closing timing of the intake valve 21 is retarded, since the overlap of the opening timing with the exhaust valve 22 is ensured, the occurrence of pump loss due to the piston 14 is prevented during the transition from the exhaust stroke to the intake stroke. can do. As a result, when the engine 10 is restarted, fuel is injected and ignited in the combustion chamber 18 of the cylinder stopped in the compression stroke following the cylinder stopped in the expansion stroke, thereby ensuring an appropriate explosive force. The engine 10 can be reliably started without using the starter motor.

  Further, when the engine 10 is restarted, the operating angle of the intake valve 21 is enlarged to delay the closing timing thereof, so that the closing timing of the exhaust valve 22 is maintained near TDC, and the increase in internal EGR is reduced. It is possible to suppress a decrease in torque generated during continuous explosion. Furthermore, it is possible to reduce the size of the valve operating mechanism by eliminating the need for the variable exhaust valve operating mechanism, and it is possible to suppress an increase in manufacturing cost.

  FIG. 9 is a schematic configuration diagram showing an engine starter according to Embodiment 3 of the present invention, and FIG. 10 is a schematic view showing opening and closing timings of intake valves and exhaust valves in the engine starter of Embodiment 3. In addition, the same code | symbol is attached | subjected to the member which has the same function as what was demonstrated in the Example mentioned above, and the overlapping description is abbreviate | omitted.

  In the engine starting device of the third embodiment, as shown in FIG. 9, the valve mechanism of the engine 10 is a variable intake / exhaust valve that controls the intake valve 21 and the exhaust valve 22 at the optimum opening / closing timing according to the operating state. Mechanisms 27 and 61 are provided. As in the first embodiment, the intake variable valve mechanism 27 advances or retards the opening timing and closing timing of the intake valve 21 by changing the opening / closing timing while keeping the operating angle of the intake valve 21 constant. It is something that can be done. The exhaust variable valve mechanism 61 has, for example, a second exhaust cam (not shown) provided adjacent to each intake cam 26 of the exhaust camshaft 24, and moves the exhaust camshaft 24 in the axial direction to exhaust the exhaust camshaft 24. By switching between the cam 26 and the second exhaust cam, the operating angle of the exhaust valve 22 can be changed to increase or decrease the lift amount, and the closing timing can be advanced or retarded.

  The ECU 42 can control the intake variable valve mechanism 27 based on the engine operating state. As shown in FIG. 10, when the engine 10 is restarted, the opening / closing timing ( The opening time and closing time are delayed. On the other hand, the ECU 42 can control the variable exhaust valve mechanism 61 on the basis of the engine operating state, and when the engine 10 is restarted, the closing timing of the exhaust valve 21 is set to the opening timing of the intake valve 21 with respect to idling operation. In addition, by delaying together, the overlap between the closing timing of the exhaust valve 22 and the opening timing of the intake valve 21 is ensured to be equal to or greater than the 0 degree crank angle.

  That is, when the engine 10 is restarted, the intake variable valve mechanism 51 delays the opening timing and closing timing of the intake valve 21 from the idle region indicated by the two-dot chain line in FIG. 10 to the restart region indicated by the solid line. Thus, the period during which the combustion chamber 18 is sealed is shortened, and the piston 14 is properly raised in the cylinder in the compression stroke so that the engine 10 can be reliably restarted. Further, when the engine 10 is restarted, the closing timing of the exhaust valve 22 by the variable exhaust valve mechanism 51 is the same as that of the intake valve 21 from the idle region indicated by the two-dot chain line in FIG. 10 to the restart region indicated by the solid line. By retarding the amount, an overlap region between the closing timing of the exhaust valve 22 and the opening timing of the intake valve 21 is secured. For this reason, there is no period in which the combustion chamber 18 is in a sealed state, and generation of pump loss by the piston 14 is prevented.

  Therefore, as shown in FIGS. 9 and 10, when the automatic stop condition of the engine 10 is established, the fuel injection by the injector 37 is stopped, the ignition by the spark plug 38 is stopped, and the engine 10 is automatically stopped. In this state, when the engine restart condition is satisfied, the ECU 42 controls the intake variable valve mechanism 27 to delay the opening / closing timing of the intake valve 21, that is, the opening / closing timing and the closing timing, by a predetermined amount, thereby enabling exhaust. By controlling the variable valve mechanism 61, the operating angle of the exhaust valve 22, that is, the closing timing is retarded by a predetermined amount. A predetermined amount of fuel is injected by the injector 37 into the combustion chamber 18 of the cylinder stopped in the expansion stroke, and the air-fuel mixture is ignited by the spark plug 38.

  Then, when the cylinder stopped in the expansion stroke explodes and lowers the piston 14, the crankshaft 16 is rotated, and this rotational force is stopped in the cylinder following the cylinder stopped in the expansion stroke, that is, in the compression stroke. The piston 14 is raised and the compression stroke is started. At this time, in the cylinder stopped in the compression stroke, the closing timing of the intake valve 21 is retarded, so that the open state in the combustion chamber 18 is continued for a long time, and the rapid increase in the in-cylinder pressure is suppressed. Therefore, the in-cylinder pressure does not become a large resistance that raises the piston 14, and the compression stroke can be reliably completed by the expansion force of the cylinder stopped in the expansion stroke. Similarly, a predetermined amount of fuel is injected into the cylinder by the injector 37, and the air-fuel mixture is ignited by the spark plug 38, whereby the cylinder obtains explosive force and lowers the piston 14. At this time, the opening / closing timing of the intake valve 21 is retarded and the closing timing of the exhaust valve 22 is retarded in accordance with the opening timing of the intake valve 21, so that the closing timing of the exhaust valve 22 and the opening of the intake valve 21 are delayed. Time overlap is ensured, there is no period in which the combustion chamber 18 is in a sealed state, and pump loss due to the piston 14 can be prevented.

  Thereafter, air is sucked from the intake port 19 in a normal manner to the cylinder following the cylinder stopped in the compression stroke, a predetermined amount of fuel is injected from the injector 37, and the air-fuel mixture is ignited by the spark plug 38. As a result, the piston 14 is lowered by obtaining an explosive force, and the crankshaft 16 is driven and the engine 10 is restarted by continuing the explosive force for a predetermined time.

  As described above, in the engine starter according to the third embodiment, the intake variable valve mechanism 27 that can change the opening / closing timing of the intake valve 21 and the variable exhaust valve that can change the operating angle and closing timing of the exhaust valve 22. A mechanism 61 is provided, and the ECU 42 retards the opening / closing timing of the intake valve 21 and retards the closing timing of the exhaust valve 22 when the restart command for the engine 10 is input, and overshoots the intake valve 21. A lap is ensured, and fuel injection and ignition are performed on the cylinders in the expansion stroke detected by the crank angle sensor 41.

  Therefore, in the cylinder stopped in the expansion stroke, the explosion is properly generated and the crankshaft 16 can be rotated. In the cylinder stopped in the compression stroke, the closing timing of the intake valve 21 is delayed. The open state in the combustion chamber 18 is continued for a long time, and the increase in the in-cylinder pressure is suppressed, so that there is no large resistance for raising the piston 14, and the expansion force of the cylinder stopped in the expansion stroke is ensured. The compression stroke can be completed. Then, by delaying the closing timing of the exhaust valve 22 in accordance with the opening timing delay of the intake valve 21, an overlap of both opening timings is secured, and at the time of transition from the exhaust stroke to the intake stroke, Generation of pump loss due to the piston 14 can be prevented. As a result, when the engine 10 is restarted, fuel is injected and ignited in the combustion chamber 18 of the cylinder stopped in the compression stroke following the cylinder stopped in the expansion stroke, thereby ensuring an appropriate explosive force. The engine 10 can be reliably started without using the starter motor.

  In each of the above-described embodiments, when the restart command for the engine 10 is input, the opening / closing timings of the intake valve 21 and the exhaust valve 22 are retarded by the intake / exhaust variable valve mechanisms 27, 28, 51, 61. After that, the engine ignition start is executed. When the engine 10 is automatically stopped or after the automatic stop, the intake / exhaust variable valve mechanisms 27, 28, 51, 61 perform the intake valve 21 and the exhaust valve 22 respectively. When the engine opening / closing timing is delayed and a restart command for the engine 10 is input, the engine ignition start may be executed.

  In each of the above-described embodiments, when the engine 10 is started, fuel is injected into the combustion chamber 18 of the cylinder that is stopped in the expansion stroke, and combustion is performed by ignition. In this case, the fuel injection amount may be set based on the stop crank angle, the engine coolant temperature, and the crankcase internal pressure. That is, the volume of the combustion chamber 18 can be determined from the stop crank angle, the air density can be determined from the engine coolant temperature, and the cylinder pressure can be determined from the crankcase internal pressure. Therefore, the optimum fuel injection amount can be set based on these data.

  Further, in each of the above-described embodiments, the engine starter of the present invention is applied as a restarter when the engine 10 is automatically stopped. However, from the state where the engine 10 is completely stopped, as a starter by an ignition key switch. Can also be applied.

  In each of the above-described embodiments, the engine starter according to the present invention has been described as applied to an in-cylinder four-cylinder engine. However, the present invention is not limited to this type of engine, but a six-cylinder engine, an in-line type or a V-type engine. It can also be applied to.

  As described above, the engine starter according to the present invention delays the closing timing of the intake valve while ensuring an overlap between the closing timing of the exhaust valve and the opening timing of the intake valve, and then performs the operation on the cylinder in the expansion stroke. The engine is started by executing fuel injection and ignition, and any type of engine can be used as long as it is an in-cylinder injection type engine.

1 is a schematic configuration diagram showing an engine starter according to Embodiment 1 of the present invention. 3 is a flowchart illustrating engine control in the engine starter according to the first embodiment. It is the schematic showing the in-cylinder behavior at the time of an engine stop. It is the schematic showing the opening / closing timing of an intake valve and an exhaust valve. It is a graph showing the change of each cylinder pressure and crank angle of # 1 cylinder and # 3 cylinder. It is a graph showing the in-cylinder pressure with respect to a crank angle. It is a schematic block diagram showing the engine starting apparatus which concerns on Example 2 of this invention. It is the schematic showing the opening-and-closing timing of the intake valve and the exhaust valve in the engine starting device of Example 2. It is a schematic block diagram showing the engine starting apparatus which concerns on Example 3 of this invention. It is the schematic showing the opening-and-closing timing of the intake valve and the exhaust valve in the engine starting device of Example 3. It is the schematic showing the opening / closing timing of the intake valve and exhaust valve in the conventional engine starting apparatus. It is a graph showing the in-cylinder pressure with respect to a crank angle.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Engine 14 Piston 16 Crankshaft 18 Combustion chamber 19 Intake port 20 Exhaust port 21 Intake valve 22 Exhaust valve 27, 51 Intake variable valve mechanism 28, 61 Exhaust variable valve mechanism 37 Injector (fuel injection means)
38 Spark plug (ignition means)
42 Electronic control unit, ECU (control means)
44 Crank angle sensor (crank angle detection means)

Claims (8)

  A combustion chamber, an intake port and an exhaust port communicating with the combustion chamber, an intake valve and an exhaust valve for opening and closing the intake port and the exhaust port, fuel injection means for injecting fuel into the combustion chamber, and the combustion chamber Ignition means for igniting the air-fuel mixture, crank angle detection means for detecting the crank angle of the engine, and the closing timing of the intake valve while ensuring an overlap between the closing timing of the exhaust valve and the opening timing of the intake valve A variable valve means that can be changed, and a cylinder that is in an expansion stroke based on the detection result of the crank angle detection means while retarding the closing timing of the intake valve by the variable valve means by the time of starting. An engine starter comprising: control means for executing fuel injection by the fuel injection means at the start and for executing ignition by the ignition means.   2. The engine starter according to claim 1, wherein the control means is a cylinder in an expansion stroke after delaying a closing timing of the intake valve by the variable valve means with respect to a cylinder in a compression stroke when the engine is started. The engine starting device is characterized in that the fuel injection and the ignition are performed on the engine.   2. The engine starting device according to claim 1, wherein the control means retards the closing timing of the intake valve by the variable valve means for the cylinder in the compression stroke when the engine is stopped, and enters the expansion stroke when the engine is started. An engine starter that performs the fuel injection and the ignition for a cylinder.   2. The engine starter according to claim 1, wherein the variable valve means retards the opening timing of the exhaust valve while ensuring an overlap between the closing timing of the exhaust valve and the opening timing of the intake valve. An engine starter characterized by retarding the closing timing of the intake valve.   5. The engine starter according to claim 1, wherein the variable valve operating means does not change an opening period of the intake valve and the exhaust valve, and changes an opening / closing timing of the intake valve and the exhaust gas. An engine starter characterized in that the valve opening and closing timing is retarded by substantially the same amount.   5. The engine starting device according to claim 1, wherein the variable valve operating means delays only the closing timing of the intake valve by extending an opening period of the intake valve. A characteristic engine starting device.   5. The engine starting device according to claim 1, wherein the variable valve operating means delays only an opening timing of the exhaust valve by extending an opening period of the exhaust valve. A characteristic engine starting device. 5. The engine starting device according to claim 1, wherein the variable valve operating unit sets the overlap between the closing timing of the exhaust valve and the opening timing of the intake valve to a crank angle of 0 °, and An engine starter characterized by retarding the closing timing of the intake valve.

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