JP2007085238A - Engine control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an engine control device capable of stopping an engine at a predetermined crank angle without installing a braking device. <P>SOLUTION: This engine control device 1 stops the engine 2 for a vehicle at the predetermined crank angle. The engine control device comprises an engine stop means 18 which when specified requirements are satisfied, stops the supply of a fuel to the engine, a crank angle sensor 16 detecting a crank angle, a rotational speed sensor 14 detecting a rotational speed, a top dead center rotational speed detection means 26 which after the supply of the fuel is stopped, detects the rotational speed of the engine when the piston of the engine is passed through the compression top dead center on the basis of the detected crank angle and rotational speed, and a generator control means 20 which when the rotational speed detected by the top dead center rotational speed detection means comes within a predetermined range, maintains a predetermined power generation amount, and when it is large, the power generation amount is increased and when it is small, the power generation amount is decreased. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an engine control device, and more particularly to an engine control device that stops a vehicle engine at a predetermined crank angle.

In recent years, in order to further reduce fuel consumption, in order to reduce carbon dioxide emissions, an increasing number of vehicles have adopted a so-called idle stop that automatically stops the engine when the engine is idle and then starts the engine again. Yes. If a starter motor for starting is used to restart the engine stopped by this idle stop, not only will it take longer to complete the start of the engine, but the life of the starter motor will be increased by frequent use. There is a problem that becomes shorter.
Japanese Utility Model Laid-Open No. 60-128975 (Patent Document 1) describes a Renoir cycle start internal combustion engine that starts an engine without using a starter motor. In this Renoir cycle start type internal combustion engine, when the engine is stopped, the braking device is operated at a predetermined timing, and the engine is stopped in a state where any cylinder of the engine is in the expansion stroke. When starting the engine, the engine is started by generating a starting torque by burning the air-fuel mixture in the cylinder in the expansion stroke.

Japanese Utility Model Publication No. 60-128975

However, in the Renoir cycle start type internal combustion engine described in Japanese Utility Model Publication No. 60-128975, there is a problem that it is necessary to provide a special braking device for the crankshaft so that the engine stops at a predetermined crank angle. is there.
Therefore, an object of the present invention is to provide an engine control device that can stop an engine at a predetermined crank angle without providing a special braking device.

  In order to solve the above-described problems, the present invention provides an engine control device for stopping a vehicle engine connected to a generator at a predetermined crank angle, and when a predetermined engine stop condition is satisfied, fuel to the engine is Engine stop means for stopping the supply of the engine and automatically stopping the engine, a crank angle sensor for detecting the crank angle of the engine, a rotation speed sensor for detecting the engine speed, and the engine stop means for supplying fuel to the engine After stopping the supply of the engine, based on the crank angle detected by the crank angle sensor and the rotation speed detected by the rotation speed sensor, the engine rotation speed when the engine piston passes the compression top dead center is detected. The top dead center rotational speed detection means and the rotational speed detected by the top dead center rotational speed detection means are within a predetermined range. When the power generation amount is maintained and larger than the predetermined range, the power generation amount of the generator is increased so as to increase the engine load. When the power generation amount is smaller than the predetermined range, the engine load is reduced. And a generator control means for reducing the power generation amount of the generator.

  In the present invention configured as above, the engine stop means stops the fuel supply to the engine and automatically stops the engine when a predetermined engine stop condition is satisfied. The top dead center rotational speed detection means is configured to detect the engine speed based on the crank angle detected by the crank angle sensor and the rotational speed detected by the rotational speed sensor after the engine stop means stops supplying fuel to the engine. The engine speed when the piston passes through the compression top dead center is detected. The generator control means maintains a predetermined power generation amount when the rotational speed detected by the top dead center rotational speed detection means is within a predetermined range, and generates a power generation amount when the rotational speed is larger than the predetermined range. If the value is smaller than the predetermined range, the power generation amount is decreased.

  According to the present invention configured as described above, the generator control means adjusts the power generation amount of the generator so as to make the decrease in the engine speed abruptly, moderate or maintain as it is. The engine can be stopped at a predetermined crank angle without providing a device.

  In the present invention, it is preferable that the generator control means is the timing at which the piston of the engine next reaches the compression top dead center when the rotational speed detected by the top dead center rotational speed detection means is outside a predetermined range. In addition, the power generation amount is increased or decreased for a predetermined time.

  In the present invention configured as described above, when the rotational speed detected by the top dead center rotational speed detection means is smaller than the predetermined range, the power generation amount is decreased by a predetermined time, and is larger than the predetermined range. The power generation amount is increased for a predetermined time.

  In the present invention, preferably, when a predetermined engine stop condition is satisfied, the engine speed adjusting means adjusts the engine speed to a predetermined speed before the engine stop means stops supplying fuel to the engine. Have

  According to the present invention configured as described above, the engine speed when the engine stop means stops the supply of fuel to the engine is adjusted to a predetermined speed by the speed adjustment means. It is possible to more reliably stop at a predetermined crank angle.

  In the present invention, preferably, further, when the generator control means increases the amount of power generated by the generator, the power supply voltage stabilization that suppresses an excessive increase in the voltage supplied to the electrical equipment connected to the generator. It has a making means.

  According to the present invention configured as described above, it is possible to prevent the voltage supplied to the electric equipment from becoming unstable by increasing the power generation amount of the generator in order to increase the engine load. .

  According to the engine control device of the present invention, the engine can be stopped at a predetermined crank angle without providing a special braking device.

  Next, an engine control apparatus according to an embodiment of the present invention will be described with reference to FIGS. 1 to 5. FIG. 1 is a configuration diagram of a system mounted on a vehicle including an engine control apparatus according to an embodiment of the present invention. FIG. 2 is a graph illustrating the principle of the engine control apparatus according to the present embodiment.

  First, the principle of the engine control apparatus 1 according to the present embodiment will be described with reference to FIG. In general, when the fuel supply is stopped, the engine stops after the crankshaft rotates with several inertia. For this reason, for example, in the case of a four-cylinder four-cycle engine, the engine stops after the piston has passed the compression top dead center about 10 times. FIG. 2 shows the engine rotation speed ne when the engine piston passes the compression top dead center after the fuel supply to the 4-cylinder 4-cycle engine rotating at a predetermined rotation speed is stopped, It is the graph which plotted the piston stop position (crank angle) of the cylinder in an expansion stroke at the time of an engine stop on the vertical axis.

  Here, when one of the pistons stops at an appropriate position in the expansion stroke, that is, when the crank angle stops in the range of 100 to 120 degrees after top dead center, the engine is operated without using the starter motor. Can be started. FIG. 2 shows that there is a strong correlation between the engine speed ne when the piston passes the compression top dead center and the stop position of the piston. That is, when the engine speed ne when the piston passes through the compression top dead center is within the range of the speed indicated by hatching in FIG. 2, the engine operates at an appropriate crank angle indicated by R in FIG. You can see that it is stopped. The engine control apparatus 1 according to the present embodiment increases the engine load by the generator when the engine speed when the piston passes the compression top dead center is higher than the predetermined speed range, and the predetermined engine speed is increased. When the engine load is lower than the range, the engine load is reduced to stop the engine at an appropriate crank angle.

  As shown in FIG. 1, an engine 2 mounted on a vehicle is controlled by an ECU (Engine Control Unit) 4. A generator 6 is connected to the output shaft of the engine 2, and the battery 8 is charged by the generator 6. In addition, electrical equipment such as a car stereo, an air conditioner, and a car navigation system mounted on the vehicle is connected to the generator 6 and the battery 8 as a load 10. Further, a variable resistor 12 for adjusting a voltage supplied from the generator 6 to the battery 8 and the load 10 is connected between the generator 6 and the battery 8. Further, the engine 2 includes a rotation speed sensor 14 which is a rotation speed measuring means for detecting the rotation speed of the crankshaft 2a of the engine 2 and a cam angle which is a crank angle sensor for detecting the rotation angle of the camshaft 2f of the engine 2. A sensor 16 is attached.

  Specifically, the ECU 4 includes a CPU (Central Processing Unit), a memory, a program stored therein, various interfaces, and the like (not shown). The ECU 4 realizes various functions such as fuel injection amount control and ignition timing control of the engine 2 based on detection results from various sensors mounted on the vehicle. The engine control apparatus 1 according to the present embodiment is realized as one function of the ECU 4, and includes an engine stop means 18, a generator control means 20, a rotation speed adjustment means 22, a variable resistance control means 24, a top dead center, and the like built in the ECU 4. The rotation speed detection means 26 and the rotation speed sensor 14 and the cam angle sensor 16 connected to the ECU 4 are configured. The variable resistor 12 and the variable resistance control unit 24 function as a power supply voltage stabilization unit.

  The generator 6 is connected to the crankshaft 2a of the engine 2 via a belt (not shown) and a pulley (not shown), and is configured to convert a part of the engine output into electric energy. Further, the generator 6 includes a field coil (not shown) and an armature (not shown), and these are rotated relative to each other by the engine output to generate an electromotive force on the armature (not shown). Will occur. Further, the magnitude of the electromotive force generated by the generator 6 is controlled by changing the current flowing through the field coil (not shown).

  The battery 8 has a positive terminal connected to the positive output terminal of the generator 6 via the variable resistor 12, and a negative terminal connected to the negative output terminal of the generator 6. Thereby, the electric power generated by the generator 6 is charged in the battery 8. Various batteries such as a lead battery, a nickel metal hydride battery, and a nickel cadmium battery can be used as the battery 8.

  The load 10 is a generic term for electric devices that are mounted on a vehicle and consume the electric power generated by the generator 6, and specifically includes a car stereo, an air conditioner, a car navigation system, and the like. The generator 6 and the battery 8 are connected in parallel to the load 10. When no power is generated by the generator 6, power is supplied from the battery 8 to the load 10. Further, when electric power is generated by the generator 6, the generated electric power is configured to be charged to the battery 8 and supplied to the load 10. Further, as will be described later, the voltage supplied to the load 10 is configured to be stabilized by the variable resistor 12.

The variable resistor 12 is connected between the generator 6 and the battery 8 and is configured such that its resistance value is changed by the variable resistance control means 24.
The rotation speed sensor 14 is configured to detect the rotation speed of the crankshaft 2 a of the engine 2 and input the value to the ECU 4.

The cam angle sensor 16 is configured to detect the rotation angle of the cam shaft 2 f of the engine 2 and input the value to the ECU 4.
The engine stop means 18 is incorporated in the ECU 4 and sends a signal to the fuel injection valve 2e of the engine 2 based on information such as the vehicle speed S, brake switch on / off, engine speed N, etc., input to the ECU 4 and fuel. Is stopped and the engine is automatically stopped.

  The engine speed adjusting means 22 is built in the ECU 4, and when a predetermined engine stop condition is detected by the engine stop means 18, the engine speed N is set to a predetermined target engine speed N1 before the fuel supply is stopped. Configured to control. The rotational speed adjusting means 22 adjusts the engine rotational speed by sending a signal to the spark plug 2c of the engine 2 and adjusting the ignition timing.

  The top dead center rotational speed detection means 26 is built in the ECU 4 and after the fuel supply to the engine 2 is stopped based on the crank angle detected by the cam angle sensor 16 and the engine rotational speed detected by the rotational speed sensor 14. The engine speed when the piston 2b passes through the compression top dead center is detected.

  The generator control means 20 is built in the ECU 4 and configured to increase or decrease the amount of power generated by the generator 6 based on the engine speed detected by the top dead center speed detection means 26. The generator control means 20 maintains the power generation amount as it is when the engine speed is within a predetermined range, decreases the power generation amount when it is smaller than the predetermined range, and is larger than the predetermined range. In order to increase power generation.

  The variable resistance control unit 24 is built in the ECU 4 and is configured to prevent an excessive voltage from being supplied to the load 10 when the generator control unit 20 increases the amount of power generated by the generator 6. Yes. When the power generation amount is increased, the variable resistance control unit 24 increases the resistance value of the variable resistance 12 and decreases the voltage supplied to the load 10.

Next, the operation of the engine control apparatus according to the embodiment of the present invention will be described with reference to FIGS. FIG. 3 is a flowchart showing the operation of the engine control apparatus according to this embodiment.
First, in step S1 of FIG. 3, the vehicle speed S of the vehicle, the state of the brake switch, and the engine speed N are input from various sensors to the engine stop means 18 of the ECU 4. Next, in step S2, it is determined whether or not a predetermined engine stop condition is satisfied. Specifically, when the brake switch is turned on and the vehicle speed S is equal to or lower than a predetermined vehicle speed, it is determined that the condition is suitable for performing idling stop. When the predetermined engine stop condition is not satisfied, the process returns to step S1 and the above processing is repeated. When the predetermined engine stop condition is satisfied, the process proceeds to step S3 and idling stop is executed.

  In step S3, the generator control means 20 sets the power generation amount of the generator 6 to a predetermined reference power generation amount. Thereby, a substantially constant load acts on the output shaft of the engine 2. Specifically, the generator control means 20 controls the amount of power generated by the generator 6 by changing the current passed through the field coil of the generator 6. In the present embodiment, the generator control means 20 controls the generator 6 so that the output current becomes 15A.

  In step S4, the shift range is set to neutral, and the output shaft of the engine 2 and the vehicle axle are separated. Next, in step S5, the rotation speed adjusting means 22 of the ECU 4 sets a target rotation speed N1 of the engine 2. In the present embodiment, the rotation speed adjusting means 22 sets the target rotation speed N1 to 850 rpm. Further, in step S6, the rotation speed adjusting means 22 sends a signal to the spark plug 2c, and adjusts the ignition timing so that the engine rotation speed N approaches the target rotation speed N1.

  Next, in step S7, the engine speed N and the target speed N1 are compared. If the engine speed N and the target speed N1 match, the process proceeds to step S8, and the engine speed N and the target speed N1. If the numbers N1 do not match, the process returns to step S6 and the adjustment of the ignition timing is repeated. Next, in step S8, the engine stop means 18 of the ECU 4 sends a signal to the fuel injection valve 2e of the engine 2 to stop the fuel supply.

  FIG. 4 is a graph showing temporal changes in the engine speed when the engine is stopped. As shown in FIG. 4, when the engine stop condition in step S2 is satisfied at time t1, the generator control means 20 sets the power generation amount of the generator 6 to a predetermined power generation amount in step S3. At this time, the rotation speed adjustment means 22 starts control of the engine rotation speed so that the engine rotation speed N becomes the target rotation speed N1 (steps S5 to S7). Next, when the engine speed N reaches the target speed N1 at time t2, the engine stop means 18 stops the fuel supply to the fuel injection valve 2e (step S8).

  The top dead center rotational speed detection means 26 detects the engine rotational speed N2 at the moment when any piston 2b of the engine 2 passes the compression top dead center after a predetermined time has elapsed from the stop of fuel supply (t3). Specifically, the engine speed signal detected by the speed sensor 14 is input to the top dead center speed detecting means 26 every moment, and the top dead center speed detecting means 26 reaches time t3. After that, the top dead center speed N2, which is the engine speed at the moment when the cam angle sensor 16 first detects the compression top dead center of the piston 2b, is sampled.

  In step S9, the generator control means 20 determines whether or not the sampled top dead center rotational speed N2 is within a predetermined range between α and β. In the present embodiment, the predetermined range of the rotational speed is set to 500 rpm or more and 530 rpm or less. When the top dead center rotational speed N2 is within the predetermined range, the process proceeds to step S10, and when it is outside the predetermined range, the process proceeds to step S11.

If the top dead center rotational speed N2 is within the predetermined range, the engine rotational speed continues to decrease as it is, so that there is a very high probability that the engine 2 will stop at the proper piston position. The power generation amount set at t1 (step S3) is maintained as it is, and the processing of the flowchart of FIG.
On the other hand, in step S11, it is determined whether or not the top dead center rotational speed N2 is smaller than a predetermined rotational speed α. When the top dead center rotational speed N2 is smaller than the predetermined rotational speed α, the process proceeds to step S12.

  When the top dead center rotational speed N2 is smaller than the predetermined rotational speed α, if the engine rotational speed continues to decrease as it is, there is a high possibility that the piston 2b stops before an appropriate position. Therefore, in step S12, the generator control means 20 reduces the amount of power generated by the generator 6, thereby reducing the load acting on the engine 2 so that the piston 2b can reach an appropriate position. Specifically, after the top dead center rotational speed N2 is sampled, the generator control means 20 performs a predetermined time from the moment when the cam angle sensor 16 next detects the compression top dead center of the piston 2b. The generator 6 is controlled so that the power generation amount decreases by a predetermined amount.

  In the present embodiment, the power generation amount to be reduced is determined based on FIG. FIG. 5 is a graph showing an example of the relationship between the top dead center rotational speed N2 and the power generation amount of the generator 6. As shown in FIG. 5, when the top dead center rotational speed N2 is not less than α and not more than β, the output current of the generator 6 is set to 15 A, which is the reference power generation amount. Further, when the top dead center rotational speed N2 is smaller than α, the power generation amount is reduced according to the rotational speed. Therefore, as the detected top dead center speed N2 is smaller, the output current of the generator 6 is reduced and the engine load is reduced. In the present embodiment, the power generation amount determined based on FIG. 5 is set for 300 msec after passing through the compression top dead center of the piston, and the processing of the flowchart of FIG. 3 ends. As described above, the load of the generator 6 acting on the engine is reduced over a period of 300 msec, so that the decrease in the engine speed becomes more gradual than when the reference power generation amount is maintained, and the piston 2b Stops at the proper position.

  On the other hand, if it is determined in step S11 that the top dead center rotational speed N2 is greater than the predetermined rotational speed α, that is, if the top dead center rotational speed N2 is greater than the predetermined rotational speed β, the process proceeds to step S13. . Thus, when the top dead center rotational speed N2 is larger than the predetermined rotational speed β, the piston 2b does not stop at the proper position and passes the proper position even if the engine speed continues to decrease. Probability is high. Therefore, in the processing after step S13, the amount of power generated by the generator 6 is increased, thereby increasing the load acting on the engine 2 so that the piston 2b can be stopped at an appropriate position.

  First, in step S <b> 13, the variable resistance control unit 24 increases the resistance value of the variable resistance 12 so that an excessive voltage is not supplied to the load 10. That is, in general, when the charge capacity of the battery 8 is low, the idling stop is prohibited. Therefore, the process of increasing the power generation amount of the generator 6 is performed only when the charge capacity of the battery 8 is high. It is done. Thus, when the state of charge of the battery 8 is good, even if the output current of the generator 6 is increased, the increased current does not flow into the battery 8 but is supplied to the load 10 as it is. As a result, the voltage supplied to the load 10 may increase rapidly. Therefore, in step S13, the resistance value of the variable resistor 12 is increased in advance before increasing the power generation amount of the generator 6 to prevent a rapid voltage increase.

  In step S <b> 14, the generator control means 20 increases the amount of power generated by the generator 6 and increases the load acting on the engine 2. The amount of power generation to be increased is determined based on FIG. 5 as in step S12. In the present embodiment, the power generation amount determined in this way is set for 300 msec after passing through the compression top dead center of the piston, and the processing of the flowchart of FIG. 3 is completed. In this way, the load on the generator 6 acting on the engine is reduced over a period of 300 msec, so that the engine speed decreases more rapidly than when the reference power generation amount is maintained, and the piston 2b Stops at the proper position.

  By the above control, the engine 2 is stopped at an appropriate crank angle with a very high probability. Thereby, when starting the engine 2 next time, the engine can be started without using the starter motor by burning the air-fuel mixture in the cylinder in which the piston 2b is stopped at an appropriate position.

  According to the engine control apparatus of the embodiment of the present invention, the generator control means adjusts the power generation amount of the generator to make the decrease in the engine speed abrupt, moderate, or as it is. The engine can be stopped at a predetermined crank angle without providing a braking device.

  According to the engine control apparatus of the present embodiment, the engine speed when the engine stop means stops the supply of fuel to the engine is adjusted to the predetermined speed by the speed adjustment means. It is possible to reliably stop at a predetermined crank angle.

  According to the engine control apparatus of the present embodiment, the resistance value of the variable resistor is increased when increasing the power generation amount of the generator, so that an excessive voltage is applied to the electrical equipment by increasing the power generation amount of the generator. It can be prevented from being supplied.

  As mentioned above, although preferable embodiment of this invention was described, a various change can be added to embodiment mentioned above. In particular, in the above-described embodiment, the present invention is applied to a four-cylinder four-cycle engine, but the present invention can be applied to other various engines.

  Therefore, the various conditions in the above-described embodiment can be changed as appropriate according to the engine to be applied. For example, in the above-described embodiment, the engine speed at the moment when any piston passes the compression top dead center after a predetermined time has elapsed from the stop of fuel supply is set as the top dead center speed, and the generator is generated based on this. However, the top dead center rotational speed can be determined in various ways. For example, the engine speed at the moment when one of the pistons passes the compression top dead center immediately after stopping the fuel supply may be set as the top dead center speed. Further, the engine speed at the moment when the piston passes the compression top dead center a predetermined number of times after the fuel supply is stopped can be set as the top dead center speed. Furthermore, in the above-described embodiment, the range of the top dead center rotation number for maintaining the power generation amount of the generator as it is is one, but two or more ranges may be set.

  In the above-described embodiment, the engine speed is detected by measuring the rotation of the crankshaft, and the crank angle is detected by measuring the rotation of the camshaft. It can be detected by any means. Further, the engine speed and the crank angle can be obtained based on detection signals of the same sensor. In this case, a single sensor functions as a crank angle sensor and a crank angle sensor.

It is a block diagram of the system mounted in the vehicle containing the engine control apparatus by embodiment of this invention. It is a graph explaining the principle of the engine control apparatus by this embodiment. It is a flowchart which shows the effect | action of the engine control apparatus by this embodiment. It is a graph showing the time change of the engine speed at the time of an engine stop. It is a graph which shows an example of the relationship between a top dead center rotation speed and the electric power generation amount of a generator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine control apparatus by this embodiment 2 Engine 2a Crankshaft 2b Piston 2c Spark plug 2d Valve 2e Fuel injection valve 2f Camshaft 4 ECU
6 Generator 8 Battery 10 Load 12 Variable resistance 14 Speed sensor 16 Cam angle sensor 18 Engine stop means 20 Generator control means 22 Speed adjustment means 24 Variable resistance control means 26 Top dead center speed detection means

Claims (4)

An engine control device that stops a vehicle engine connected to a generator at a predetermined crank angle,
Engine stop means for stopping fuel supply to the engine and automatically stopping the engine when a predetermined engine stop condition is satisfied;
A crank angle sensor for detecting the crank angle of the engine;
A rotational speed sensor for detecting the rotational speed of the engine;
After the engine stop means stops the fuel supply to the engine, the piston of the engine is compressed based on the crank angle detected by the crank angle sensor and the rotation speed detected by the rotation speed sensor. Top dead center rotational speed detection means for detecting the rotational speed of the engine when passing through the dead center;
When the rotational speed detected by the top dead center rotational speed detection means is within a predetermined range, the predetermined power generation amount is maintained, and when the rotational speed is larger than the predetermined range, the engine load is reduced. A generator control means for increasing the power generation amount of the generator so as to increase and, if smaller than the predetermined range, reducing the power generation amount of the generator so as to reduce the load on the engine;
An engine control device comprising:   The generator control means generates power when the engine piston reaches the compression top dead center next when the rotational speed detected by the top dead center rotational speed detection means is outside the predetermined range. 2. The engine control device according to claim 1, wherein the amount is increased or decreased for a predetermined time.   The engine further comprises a speed adjusting means for adjusting the engine speed to a predetermined speed before the engine stopping means stops the fuel supply to the engine when the predetermined engine stop condition is satisfied. The engine control apparatus according to 1 or 2.   Furthermore, when the generator control means increases the power generation amount of the generator, it has power supply voltage stabilization means for suppressing an excessive increase in voltage supplied to the electrical equipment connected to the generator. The engine control device according to any one of claims 1 to 3.

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