JPH1182076A - Intake and exhaust valve control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the contamination of an intake system part by unburnt gas or back flow of exhaust gas by continuing a general operation to the first exhaust stroke in each cylinder when the operation stop of an engine is required, stopping the operation on and after it, and fixing intake and exhaust valves in open state until the rotation of the engine is stopped. SOLUTION: When a first exhaust stroke is judged after OFF of an ignition switch, the fuel injection and ignition after the end of the exhaust stroke are prohibited. Intake and exhaust valves 3, 4 are fixed in open state by a valve driving device. It is judged whether the engine rotating speed is 0 or not on the basis of the signal from a crank angle sensor 10, and it is then judged whether a fixed time passed after the engine rotating speed was 0. When it is judged that the engine is perfectly stopped after continuation of a fixed time or more, the intake and exhaust valves 3, 4 are set in prescribed positions for opening and closing in the following starting. According to this structure, the contamination of an intake system part by the after burning of unburnt gas or the back flow of exhaust gas can be prevented, and the startability can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for stopping an engine in an internal combustion engine having an electronically controlled intake / exhaust valve for electronically controlling opening and closing.

[0002]

2. Description of the Related Art In an electronically controlled internal combustion engine, a crank angle sensor is provided, and fuel injection control and ignition control are performed for each cylinder based on the detected crank angle position. When the engine is stopped, when the ignition switch is turned off, fuel injection and ignition are stopped at the same time to stop the operation.

[0003]

However, when the fuel injection and ignition are stopped at the same time as the ignition switch is turned off as described above, the intake system parts are contaminated by unburned gas afterburning or backflow of exhaust gas. There has been a problem that the air-fuel ratio at the time of restarting varies due to residual unburned gas and residual combustion gas, thereby impairing startability.

[0004] In the electronically controlled internal combustion engine,
After the start, fuel injection control and ignition control for each cylinder can be performed based on a signal from the crank angle sensor.A general crank angle sensor includes a reference signal output for each reference crank angle position of each cylinder. Since the crank angle is detected based on the unit angle signal output for each minute crank angle, the crank angle position cannot be detected until the cylinder discrimination signal is detected at the time of starting. Control cannot be performed.

[0005] For this reason, it has been proposed to store the crank angle position at the time of engine stop and try to start cylinder-specific control immediately after the engine is started. A cylinder receives a compression reaction,
In response to the reaction force from the intake / exhaust valve driving cam, the rotation of the rotation occurs in the opposite direction immediately before the stop, i.e., the rotation in the opposite direction occurs. However, since it was not possible to detect the crank angle position, an accurate crank angle position could not be stored, and it was not practical.

For this reason, as disclosed in Japanese Patent Application Laid-Open No. 60-6012, a device capable of detecting the absolute position of the crank angle is provided so that control for each cylinder can be started from the start. Although there is something, the hardware is complicated and the cost increases. Some diesel engines are provided with a decompression mechanism that fixes the intake and exhaust valves to the open state during reverse rotation as a technology to prevent reverse rotation operation of the engine.This is to prevent reverse combustion operation. However, it is not a technique that can prevent the swing back when stopping.

The present invention has been made in view of such conventional problems, and prevents contamination of intake system components due to backflow of unburned gas and exhaust gas when the engine is stopped, and prevents unburned gas and residual combustion gas. It is an object of the present invention to suppress the variation of the air-fuel ratio at the time of starting due to the above. It is another object of the present invention to prevent cylinder-based control from starting immediately after starting by preventing the rotation from swinging back.

[0008]

SUMMARY OF THE INVENTION Accordingly, an invention according to claim 1 is an intake / exhaust valve control apparatus for an internal combustion engine having an electronically controlled intake / exhaust valve whose opening and closing are electronically controlled. At the time of a stop request, normal operation is continued until the first exhaust stroke in each cylinder, after which operation is stopped and the intake and exhaust valves are fixed at least until the rotation of the engine is stopped. And

According to the first aspect of the invention, since the intake and exhaust valves are fixed to the open state after the exhaust stroke in each cylinder, the afterburning of the unburned gas and the backflow of the exhaust gas are eliminated, and the contamination of the intake system components is reduced. Is prevented. Further, the unburned gas and the combustion gas remain in the combustion chamber, and the air-fuel ratio at the time of restarting does not vary, so that the startability is improved and the fuel efficiency and the exhaust emission can be improved.

Further, since the intake / exhaust valve is fixed in the open state, the intake / exhaust valve does not receive a compression reaction force immediately before the rotation is stopped, and
Since the opening and closing of the intake and exhaust valves is performed electronically without using a cam, there is no reaction force due to the climbing of the cam, so that it is possible to prevent the rotation from swinging back. According to a second aspect of the present invention, there is provided an intake / exhaust valve control apparatus for an internal combustion engine having an electronically controlled intake / exhaust valve whose opening and closing are electronically controlled. Operation is continued until the stroke, and after that, the operation is stopped, and the intake and exhaust valves are opened when the rotation of the engine is in a low-speed state close to stop, and the intake and exhaust valves are at least until the rotation of the engine stops. The valve is fixed in an open state.

According to the second aspect of the invention, the same operation and effect as those of the first aspect are obtained, and the compression / reaction force is obtained by operating the intake / exhaust valve normally until immediately before the rotation stops. Accordingly, the time required for stopping the rotation can be reduced. This can prevent the parts from being damaged due to running out of the lubricating oil in the sliding portion (for example, between the piston and the cylinder).

Further, the invention according to claim 3 includes means for storing a crank angle position when the engine is stopped, and performs cylinder-by-cylinder control from the beginning of the start based on the stored crank angle position at the time of start. Features. According to the invention according to claim 3, since the rotation does not swing back when the engine is stopped as described above, the crank angle position at the time of stop can be accurately detected even with a crank angle sensor that cannot detect reverse rotation, At the time of restart based on the detected value, fuel injection control and ignition control for each cylinder can be started immediately after the start, so that the startability can be improved by shortening the start-up time, and the fuel efficiency and exhaust emission can be improved. it can.

The invention according to claim 4 is characterized in that the intake / exhaust valve is set at a predetermined position after the rotation of the engine is stopped. According to the fourth aspect, after the rotation of the engine is stopped, the intake / exhaust valve can be set at a predetermined position and be on standby for restarting.

Further, the invention according to claim 5 is characterized in that, after the intake and exhaust valves are fixed in an open state, the fixed state is maintained until a start operation of the engine is started. According to the fifth aspect of the present invention, the control may be simplified since the open state may be fixed until the restart operation is started.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1 showing the overall configuration of one embodiment, an internal combustion engine 1 is provided with an intake valve 3 and an exhaust valve 4 whose opening and closing are electronically controlled by a valve driving device 2. A fuel injection valve 6 is mounted on an intake port 5 of each cylinder, and an ignition plug 8 and an ignition coil 9 are mounted on a combustion chamber 7. Further, a crank angle sensor 10 that outputs a reference signal at a reference crank angle of each cylinder and outputs a unit angle signal for each minute crank angle is mounted on the engine body.

The signals from the crank angle sensor 10 and the like are output to a control unit 11 and the control unit 11
Outputs a fuel injection signal to the fuel injection valve 6 based on these detection signals to perform fuel injection control, and outputs an ignition signal to the ignition coil 9 to perform ignition control. 2 to control the opening and closing of the intake valve 3 and the exhaust valve 4 by outputting a valve drive signal.

FIG. 2 shows the structure of the valve driving device 2. In FIG. 2, the intake valve 3 (or the exhaust valve 4) is an elongated valve rod 21.
A power piston 22 slidably fitted in a sleeve 23 is connected to the valve rod 21, and a control valve 24 is slidably fitted outside the sleeve 23. On both sides of the power piston 22, variable volume chambers 25 and 26 are defined,
When the control valve 24 is in the position shown in the drawing by being attracted by the magnet 27 on the left side of the drawing, the high-pressure liquid flows into the left-hand room 25 through the port 28 of the control valve 24 while the inside of the right-hand room 26 is shown. Is discharged to the low pressure side via the port 29 of the control valve 24. Thus, the valve rod 21 moves rightward to the position shown in the drawing while compressing the air in the air chamber 31 by the braking piston 30 connected to the valve rod 21, and opens the intake valve 2.

When the holding effect of the magnet 27 is negated by the bias of the coil 32 on the left side in the figure, the control valve 24 moves rightward in the figure by the attraction force of the spring 33 and the magnet 34 on the right side. Thereby, the high-pressure liquid in the chamber 25 flows out to the low-pressure side via the port 32 of the control valve 24, and the control valve 24
Since the communication with the port 28 is maintained, the valve rod 21 remains open to the low pressure side, and in this state, the valve rod 21 moves leftward in the figure integrally with the braking piston 30 by the compressed air pressure in the air chamber 30. Then, the intake valve 3 is seated on the valve seat 35 and closed.

As described above, the intake valve 3 can be opened and closed by turning on and off the power supply to the coil 30. The same device is attached to the exhaust valve 4, and the opening and closing are similarly controlled. Next, control when the engine is stopped according to the first embodiment of the present invention will be described with reference to the flowchart of FIG.
This flowchart shows one cylinder, and the same flow is actually executed for each cylinder.

In step 1, it is determined whether the ignition switch is on or off. If it is determined in step 1 that the ignition switch has been turned off, then in step 2 it is determined whether or not the cylinder is in an exhaust stroke. If not, the process proceeds to step 3 in which normal operation (fuel injection, ignition) is performed.
And then returns to step 2. If it is determined that the first exhaust stroke has been reached after the ignition switch has been turned off for the cylinder, the routine proceeds to step 4, where fuel injection and ignition after the exhaust stroke is terminated are prohibited.

In step S5, the intake valve 3 and the exhaust valve 4 are fixed in an open state by the valve driving device. Next, the routine proceeds to step 6, where it is determined whether or not the engine rotational speed has become 0 based on the signal from the crank angle sensor 10, and the routine proceeds to step 7 after waiting for the rotational speed to become 0.

In step 7, it is determined whether or not the engine rotation speed has continued for a predetermined time since the engine speed became 0, and the flow proceeds to step 8 after waiting for the continuation of the predetermined time or more. In step 8,
When it is determined that the engine has completely stopped, the intake and exhaust valves are set at predetermined positions in preparation for opening and closing at the next start. By doing so, fuel injection,
Stopping the ignition and fixing the intake / exhaust valve after exhaust is completely exhausted prevents contamination of the intake system components due to afterburning of unburned gas or backflow of exhaust gas. There is no residual unburned gas or combustion gas, and there is no variation in the air-fuel ratio at the time of restart, and the startability is improved.

Further, since the intake / exhaust valves are fixed to the open state when the operation of the engine is stopped, there is no compression reaction force from the piston. Since the rotation is stopped only by the frictional force without receiving any force, the swing back of the rotation can be reliably prevented. Therefore, if the crank angle position at the time of engine stop detected based on the signal from the crank angle sensor 10 is stored, the fuel injection for each cylinder can be performed from the beginning based on the stored crank angle position at the time of restart. The ignition timing control can be started, and the starting performance is improved.

In this embodiment, the intake / exhaust valve is set at a predetermined position after the rotation of the engine is completely stopped. However, for simplicity, as shown by a dashed line in FIG. Alternatively, the intake and exhaust valves may be kept open until the next time the ignition switch is turned on. FIG. 4 is a time chart showing the piston position and the opening / closing state of the intake / exhaust valve according to the first embodiment.

Next, a second embodiment of the present invention will be described with reference to FIG.
This will be described according to the flowchart of FIG. Steps 11 to 14 are the same as steps 1 to 4 of the first embodiment. In this way, after the fuel injection and ignition are prohibited after the end of the exhaust stroke, the intake / exhaust valve is not immediately fixed in the open state, but the normal opening / closing operation is continued, and the routine proceeds to step 15.

In step 15, it is determined whether or not the rotational speed of the engine has decreased to a predetermined value N0 at a low speed close to stop.
Fix the intake and exhaust valves to the open state. Thereafter, as in the first embodiment, after waiting for the engine rotation to completely stop in step 17, the intake and exhaust valves are set to predetermined values in step 18.

Also, as described above, as indicated by a dashed line in FIG. 5, until the next time the ignition switch is turned on.
The intake and exhaust valves may be fixed in an open state. According to this embodiment, similarly to the first embodiment, afterburning of the unburned gas and contamination of the intake system components due to backflow of exhaust gas can be prevented, and unburned gas and combustion gas can be prevented from remaining. The variation in the air-fuel ratio at the time of restart is eliminated, and the startability is improved.

Further, since there is no compression reaction force from the piston and no reaction force at the time of riding on the cam, it is possible to reliably prevent the rotation from swaying back, so that the engine is restarted based on the crank angle position stored when the engine is stopped. Sometimes, fuel injection and ignition timing control for each cylinder can be started from the beginning, and starting performance is improved. Further, in the second embodiment, the intake / exhaust valve is operated normally until immediately before the rotation of the engine stops, so that the time required for stopping the rotation can be reduced by receiving the compression reaction force. This can prevent the parts from being damaged due to running out of the lubricating oil in the sliding portion (for example, between the piston and the cylinder).

FIG. 6 is a time chart showing the piston position and the open / closed state of the intake / exhaust valve according to the second embodiment.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram according to an embodiment of the present invention.

FIG. 2 is a sectional view showing the configuration of the valve drive device according to the embodiment.

FIG. 3 is a flowchart showing control of intake and exhaust valves when the engine is stopped according to the first embodiment.

FIG. 4 is a time chart showing a state of a piston position and an open / close state of an intake / exhaust valve according to the first embodiment.

FIG. 5 is a flowchart illustrating control of intake and exhaust valves when the engine is stopped according to a second embodiment.

FIG. 6 is a time chart showing a state of a piston position and an open / close state of an intake / exhaust valve according to the second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Valve drive device 3 Intake valve 4 Exhaust valve 6 Fuel injection valve 7 Combustion chamber 8 Spark plug 10 Crank angle sensor 11 Control unit

Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02D 43/00 301 F02D 43/00 301A 301G 45/00 310 45/00 310G

Claims (5)

[Claims] An intake / exhaust valve control device for an internal combustion engine having an electronically controlled intake / exhaust valve whose opening and closing are electronically controlled. When an engine operation stop request is made, each cylinder is operated until the first exhaust stroke. An intake / exhaust valve control device for an internal combustion engine, wherein the intake / exhaust valve is kept open until at least the rotation of the engine is stopped. 2. An intake / exhaust valve control system for an internal combustion engine having an electronically controlled intake / exhaust valve whose opening and closing are electronically controlled, wherein when the engine operation is requested to stop, the operation of each cylinder is continued until the first exhaust stroke. Continued, and after that, the operation was stopped, and the intake and exhaust valves were opened when the rotation of the engine was at a low speed close to stop, and the intake and exhaust valves were opened at least until the rotation of the engine stopped. An intake / exhaust valve control device for an internal combustion engine, wherein the control device is fixed to the engine. 3. The engine according to claim 1, further comprising means for storing a crank angle position when the engine is stopped, and performing control for each cylinder from the beginning of the start based on the stored crank angle position when the engine is started. Item 3. An intake / exhaust valve control device for an internal combustion engine according to item 2. 4. The intake / exhaust valve of an internal combustion engine according to claim 1, wherein the intake / exhaust valve is set at a predetermined position after the rotation of the engine is stopped. Exhaust valve control device. 5. The method according to claim 1, wherein after the intake and exhaust valves are fixed in an open state, the fixed state is maintained until a restart operation of the engine is started. An intake / exhaust valve control device for an internal combustion engine according to the above.