JP3510044B2 - Starting method of electromagnetically driven valve of internal combustion engine - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetically driven valve used as an intake / exhaust valve in an internal combustion engine, and more particularly to a method for starting the electromagnetically driven valve utilizing natural vibration of a spring-mass system.

[0002]

2. Description of the Related Art Conventionally, as an intake / exhaust valve of an internal combustion engine, a valve which is opened / closed by a cam shaft driven based on rotation of a crank shaft is generally used. From the standpoint of improving the performance of the internal combustion engine, various valve operating system variable mechanisms are being put to practical use in order to achieve the optimum valve opening / closing timing according to the operating state, and there are two-stage switching type (ON / ON). A continuously variable type has also been developed, including an OFF control type). These variable mechanisms include those that shift the rotational phase of the cam shaft, and those that have a plurality of cam profiles on the cam shaft.

However, in the intake / exhaust valve driven by the camshaft as described above, it is impossible to independently and arbitrarily set the valve lift amount, the valve opening period and the valve opening / closing timing. Therefore, in recent years, in order to meet the demand for higher performance of internal combustion engines, research on electromagnetically driven valve trains that can set those parameters to ideal values according to operating conditions has become active. There is.

For example, Japanese Patent Application Laid-Open No. 59-213913 discloses that a valve body supported at a neutral position by a biasing force of a pair of springs is acted on by electromagnetic force acting on a plunger connected to the valve body. The present invention relates to an electromagnetically driven valve having a structure for moving from a position to a fully open direction or a fully closed direction,
In particular, the starting method is disclosed. The starting method is to utilize the resonance phenomenon in order to save power.

That is, according to the teaching of physics, in a spring-mass system, neglecting friction and other losses, if an initial displacement is given, a continuous sinusoidal vibration of a natural frequency is generated, and further, If an external force that vibrates in accordance with its natural frequency is continuously applied to the mass, its amplitude will gradually increase without limit. In the starting method according to the above publication, an electromagnetic force is applied as an external force to a spring-mass system including a plunger as a mass to excite natural vibration (self-excited vibration), and finally one of the electromagnets is attracted to start the starting operation. To complete. By utilizing such a resonance phenomenon, it is possible to reduce the electromagnetic force at the time of starting, and thus the initial current for generating the electromagnetic force, and as a result,
Power saving can be achieved at the time of starting.

[0006]

In order to improve the compression ratio, the internal combustion engine is generally designed in such a size that the top dead center position of the piston interferes with the fully open position of the valve body. Therefore, in case of an unexpected situation, a recess is conventionally provided on the upper part of the piston to avoid interference with the valve body. However, recently, the mechanical coupling between the crankshaft and the camshaft has become strong, and such a recess tends to be eliminated.

When the above electromagnetically driven valve is used in an internal combustion engine having a piston not provided with such a recess, since the valve body and the crankshaft are not mechanically connected, the piston and the valve body are not connected to each other. Interference becomes a problem again. That is, considering the case where the starting method disclosed in the above publication is carried out without considering the position of the piston, in the process in which the displacement of the valve body increases due to natural vibration, the valve body reaches the vicinity of the fully open position. At that time, a situation may occur in which the piston is also near the top dead center. At this time, interference between the piston and the valve element, that is, so-called valve stamping occurs, and as a result, the electromagnetically driven valve is not normally started and the internal combustion engine is also damaged.

In view of the above situation, an object of the present invention is to provide an internal combustion engine which uses an electromagnetically driven valve as an intake / exhaust valve, and a valve body when the electromagnetically driven valve is started by utilizing the natural vibration of a spring-mass system. It is to prevent interference with the piston.

[0009]

A method of starting an electromagnetically driven valve for an internal combustion engine according to the invention of claim 1 devised to achieve the above object elastically moves a valve element to a neutral position by a spring. An electromagnetic force of an internal combustion engine that is supported and constitutes a spring-mass system, and an electromagnetic force is applied to a plunger integrated with the valve body to displace the valve body from the neutral position to the fully open position or the fully closed position. In the method of starting the drive valve,
The starting time required from the start of the excitation of the natural vibration of the spring-mass system by the electromagnetic force until the valve body reaches the fully closed position and is held at the fully closed position starts the electromagnetically driven valve.
Earliest start time to prevent valve stamping when
Starting allowance from crank angle to the latest start end time
The voltage must be within the allowable starting time that corresponds to the
Set the start timing of the magnetic drive valve, and set the crank angle position.
When it is detected that the start timing has been reached, the spring
The electromagnetic force that vibrates at the natural frequency of the mass system is
A drive current is applied to the electromagnetically driven valve to actuate the Langer.
The start time of the earliest start is detected.
Is set based on the cranking speed of the
The higher the ranking speed, the larger the drive current will be.
Characterized in that that.

According to a second aspect of the present invention, there is provided a method for starting an electromagnetically driven valve for an internal combustion engine, wherein the valve element is moved to a neutral position by a spring.
The valve, which is elastically supported to form a spring-mass system,
Electromagnetic force is applied to the plunger integrated with the body
The valve body from the neutral position to the fully open or fully closed position.
How to start the electromagnetically driven valve of the internal combustion engine
Then, the excitation of the natural vibration of the spring-mass system is caused by the electromagnetic force.
After the start, the valve body reaches the fully closed position and
The time required for starting before being retained is the electromagnetically driven valve.
Earliest start to prevent valve stamping when starting
Depending on the crank angle from the start time to the end of the latest start
Within the allowable start time corresponding to the allowable start period
Set the start timing of the electromagnetically driven valve to
When it is detected that the degree position has reached the start start time
At the electric frequency that matches the natural frequency of the spring-mass system.
A driving current is applied to the plunger to apply a magnetic force to the plunger.
Start applying the voltage to the drive valve,
Is set based on the detected cranking speed,
And increase the drive current to the electromagnetically driven valve too much.
Excessive cranking speed when unable to
When the driving current is small, the smaller the driving current,
It is characterized in that the king speed is adjusted to be small .

A method for starting an electromagnetically driven valve for an internal combustion engine according to a third aspect of the present invention is the method according to the first or second aspect of the present invention, wherein the internal combustion engine includes a plurality of cylinders.
The crank angle position has reached the start-up start time.
When the drive current is applied from the cylinder
Electromagnetic drive corresponding to the movement of the piston after being held at
Opening and closing the valves is sequentially extended to the cylinders in the next ignition sequence.
It is characterized by opening .

A method of starting an electromagnetically driven valve for an internal combustion engine according to a fourth aspect of the present invention is the method according to the first or second aspect of the invention, wherein a plurality of electromagnetically driven solenoids are provided for one cylinder.
Valve is provided, and there is no start time for starting the electromagnetically driven valves.
It is characterized by being set according to the requirements.

According to a fifth aspect of the present invention, there is provided a method for starting an electromagnetically driven valve for an internal combustion engine, wherein the valve element is moved to a neutral position by a spring.
The valve, which is elastically supported to form a spring-mass system,
Electromagnetic force is applied to the plunger integrated with the body
The valve body from the neutral position to the fully open or fully closed position.
How to start the electromagnetically driven valve of the internal combustion engine
Then, the excitation of the natural vibration of the spring-mass system is caused by the electromagnetic force.
After the start, the valve body reaches the fully closed position and
The time required for starting before being retained is the electromagnetically driven valve.
Earliest start to prevent valve stamping when starting
Depending on the crank angle from the start time to the end of the latest start
Within the allowable start time corresponding to the allowable start period
Set the start timing of the electromagnetically driven valve to
When it is detected that the degree position has reached the start start time
At the electric frequency that matches the natural frequency of the spring-mass system.
A driving current is applied to the plunger to apply a magnetic force to the plunger.
The application to the drive valve is started, and the start timing is
Cranks whose starting time is within the allowable starting time
Freely from the earliest to the latest in the angle area
It is characterized by being set .

According to the invention of claim 1, which is configured as described above.
According to such a method for starting the electromagnetically driven valve of the internal combustion engine, the valve body is
Interference with the piston is reliably avoided. Also, the valve body
Move from the fully open position to the fully closed position or from the fully closed position to the fully open position
The time it takes to move does not depend on the cranking speed
Therefore, the crank angle that can start the start is advanced.
However, at the earliest possible start according to the cranking speed
The period can be set. Also, the cranking speed is high.
The longer the start time is allowed, the shorter the
The higher the king speed, the larger the drive current.
This reduces the time required for starting.

According to the invention of claim 2, which is configured as described above.
According to such a method for starting the electromagnetically driven valve of the internal combustion engine, the valve body is
Interference with the piston is reliably avoided. Also, the valve body
Move from the fully open position to the fully closed position or from the fully closed position to the fully open position
The time it takes to move does not depend on the cranking speed
Therefore, the crank angle that can start the start is advanced.
However, at the earliest possible start according to the cranking speed
The period can be set. Also, the smaller the drive current,
It takes longer to start, but the drive current is
However, by decreasing the cranking speed, start
Allowable time is extended.

According to the invention of claim 3, electromagnetic drive is provided.
Start the valve and hold it in the fully closed position, then synchronized with the piston
Wait until the other cylinders are ready for operation.
You will be able to do without it. Also, the claims
According to the fourth aspect of the invention, it is generated from the electromagnetically driven valve in the same cylinder.
It is possible to suppress the peak value of the amount of heat that is generated.

According to the invention of claim 5, which is configured as described above.
According to such a method for starting the electromagnetically driven valve of the internal combustion engine, the valve body is
Interference with the piston is reliably avoided. Also applicable
The solenoid valve can be started earlier than the cylinder.
It has excellent engine startability.

[0018]

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is an overall schematic diagram of an electronically controlled internal combustion engine according to an embodiment of the present invention. The air required for engine combustion is filtered by the air cleaner 2, passes through the throttle body 4, and enters the surge tank (intake manifold).
At 6, the fuel is distributed to the intake pipe 7 of each cylinder. The intake air flow rate is adjusted by the throttle valve 5 provided in the throttle body 4, and the air flow meter 40
It is measured by. The intake air temperature is detected by the intake air temperature sensor 43.

The opening of the throttle valve 5 is detected by the throttle opening sensor 42. When the throttle valve 5 is fully closed, the idle switch 52 is turned on, and the output of the throttle fully closed signal is active.

On the other hand, the fuel stored in the fuel tank 10 is pumped up by the fuel pump 11, and the fuel pipe 12
Then, the fuel is injected into the intake pipe 7 by the fuel injection valve 60.

In the intake pipe 7, air and fuel are mixed,
The air-fuel mixture is sucked into the combustion chamber 21 of the engine body, that is, the cylinder 20 via the intake valve 24. In the combustion chamber 21, the air-fuel mixture is compressed by the piston 23 and then ignited to explode and burn to generate power.
The engine is cooled by the cooling water guided to the cooling water passage 22, and the temperature of the cooling water is detected by the water temperature sensor 44. The actual vehicle speed is detected by a vehicle speed sensor 53 that generates an output pulse representing the vehicle speed.

The combusted air-fuel mixture is discharged as exhaust gas to the exhaust manifold 30 via the exhaust valve 26, and is then guided to the exhaust pipe 34. The exhaust pipe 34 is provided with an O ₂ sensor 45 for detecting the oxygen concentration in the exhaust gas. Further, a catalytic converter 38 is provided in the exhaust system downstream thereof, and the catalytic converter 38 has
A three-way catalyst that simultaneously promotes the oxidation of unburned components (HC, CO) and the reduction of nitrogen oxides (NO _x ) in the exhaust gas is housed. The exhaust gas thus purified by the catalytic converter 38 is discharged into the atmosphere.

Engine electronic control unit (engine EC
U) 70 is a microcomputer system that executes fuel injection control, ignition timing control, idle speed control, intake / exhaust valve control, etc., and its hardware configuration is shown in the block diagram of FIG. Read Only Memory (RO
According to the programs stored in M) 73 and various maps, the central processing unit (CPU) 71 inputs signals from various sensors and switches through the A / D conversion circuit 75 or the input interface circuit 76, and inputs the signals. Calculation processing is executed based on the signal, and control signals for various actuators are output based on the calculation result via the drive control circuits 77a and 77d. Random access memory (RAM)
74 is used as a temporary data storage location in the arithmetic / control processing process. Also, backup RA
The M79 is supplied with power by being directly connected to the battery, and is used to store data (for example, various learning values) that should be held even when the ignition switch is off. Further, these constituent elements in the ECU are connected by a system bus 72 including an address bus, a data bus, and a control bus.

FIG. 3 is a vertical sectional view showing electromagnetic valves used as the intake valve 24 and the exhaust valve 26. A valve body 80 shown in the figure comprises a valve head (also referred to as a valve head or a valve stem) 81 and a valve shaft 82, and a valve face 81a of the valve head 81 is an internal combustion engine. A valve seat (valve seat: va
The intake / exhaust port 92 is opened and closed by seating on or off the valve seat 93. The valve shaft 82 of the valve body 80 is held by the valve guide 91 so as to be slidable in the axial direction. The valve shaft 82 has a plunger (p
lunger) 83 is fixed.

The plunger 83 is a disk-shaped member made of a soft magnetic material. An upper core 84 is disposed above the plunger 83 with a predetermined distance therebetween, and a lower core 86 is similarly disposed below the plunger 83 with a predetermined distance therebetween. There is. The upper core 84 and the lower core 86 are made of a soft magnetic material, and a case 90 made of a non-magnetic material.
Are held in a predetermined positional relationship. The upper core 84 holds an upper coil 85, and the lower core 86 holds a lower coil.
87 is gripped.

The valve shaft 82 has an upper spring (upp).
er spring) 88 and lower spring 89
Are elastically supported in the axial direction. The upper spring 88 and the lower spring 89 are balanced so that the position (neutral position) of the plunger 83 when the upper coil 85 and the lower coil 87 are not energized is an intermediate position between the upper core 84 and the lower core 86. Has been. When the plunger 83 is in the neutral position, the valve body 80 takes an intermediate position between the fully open side displacement end and the fully closed side displacement end.

With this structure, a magnetic circuit including the upper core 84, the plunger 83, and the air gap formed between them is formed around the upper coil 85. Therefore, when an electric current is passed through the upper coil 85, the magnetic flux circulates in the magnetic circuit, and an electromagnetic force is generated in the direction of reducing the air gap, that is, in the direction of displacing the plunger 83 upward. On the other hand, a magnetic circuit including a lower core 86, a plunger 83, and an air gap formed between them is formed around the lower coil 87. Therefore, when a current is applied to the lower coil 87, an electromagnetic force is generated in the direction of displacing the plunger 83 downward based on the same principle.

Thus, by alternately passing a current through the upper coil 85 and the lower coil 87, the plunger 83
Can be reciprocated up and down, that is, the valve body 80 can be alternately driven in the opening and closing directions. Engine E
The CU 70 determines the opening / closing timing of the solenoid valve based on signals from various sensors, and the drive control circuit 77d
Battery 94 to upper coil 85 and lower coil 87
The solenoid valve is driven by controlling the energization (power supply) to the solenoid valve.

FIG. 4 is a diagram showing the structure of an engine starting device. This engine is a 4-cylinder engine, and the # 1 cylinder and the # 4 cylinder have the same piston position, and the # 3 cylinder and the # 2 cylinder have the same piston position. The piston position difference is 180 ° CA. When the engine is started, the power of the starter motor 95 is transmitted to the crankshaft 98 via the starter pinion 96 and the ring gear 97, so that the crankshaft 9
8 is rotated. The speed of cranking by such a starter motor is proportional to the terminal voltage of the starter motor 95. The engine ECU 70 uses the chopper circuit 9
By changing the duty ratio signal in 8,
By controlling the voltage applied from the battery 94 to the starter motor 95, the cranking speed can be changed.

A crank angle sensor 51 is provided to detect the angle of the crank shaft. The crank angle sensor 51 is composed of a slit disk encoder 102 and a light emitter / receiver 103 attached to the crankshaft. As shown in FIG. 5, the slit disk encoder 102 is provided with, for example, one X slit and 360 Y slits. By detecting such X slits and Y slits using the light emitter / receiver 103, the rotational speed of the crankshaft and the crank angle position for each cylinder can be obtained.

The engine control processing of the ECU 70 executed in the internal combustion engine (engine) having the above hardware configuration will be described below.

The fuel injection control is basically performed by the engine 1.
Based on the intake air amount per rotation, the fuel injection amount that achieves a predetermined target air-fuel ratio, that is, the injection time by the fuel injection valve 60 is calculated, and drive control is performed to inject fuel when the predetermined crank angle is reached. The fuel injection valve 60 is controlled via the circuit 77a. The intake air amount per engine revolution is calculated from the intake air flow rate measured by the air flow meter 40 and the engine rotation speed obtained from the crank angle sensor 51. When the fuel injection amount is calculated, basic correction based on signals from the throttle opening sensor 42, the intake air temperature sensor 43, the water temperature sensor 44, and the like, and an empty correction based on the signal from the O ₂ sensor 45 are performed. A fuel ratio feedback correction, an air-fuel ratio learning correction for making the median of the feedback correction values the stoichiometric air-fuel ratio, and the like are added.

In the ignition timing control, the engine state is comprehensively determined by the engine rotation speed obtained from the crank angle sensor 51, the intake air flow rate obtained from the air flow meter 40, and signals from other sensors. Determine the optimal ignition timing.

The intake / exhaust valve control will be described in detail below. A plurality of curves indicated by solid lines in FIG. 6 indicate the relationship between the position of the plunger 83 (where the position in contact with the upper core 84 is zero) and the electromagnetic force (attraction force) exerted on the plunger 83 by the electromagnet associated with the upper core 84. 85
The value of the current flowing through is expressed as a parameter.
As shown by these curves, the electromagnetic force (suction force) acting on the plunger rapidly increases as the valve body 80 approaches the fully closed side displacement end. On the other hand, the straight line shown by the broken line in FIG. 6 similarly represents the relationship between the position of the plunger 83 and the biasing force (on the lower core 86 side) exerted on the valve body 80 by the upper spring 88 and the lower spring 89.
As can be seen from this straight line, the urging force only increases linearly even when the valve body 80 approaches the fully closed side displacement end.
The electromagnetic force generated by the electromagnet associated with the lower core 86 is also indicated by the curve in FIG. 6, and the fully closed position is simply changed to the fully open position. Therefore, as the position approaches the fully open position or the fully closed position, an electromagnetic force exceeding the biasing force can be obtained with a smaller current as compared with the neutral position. Next, a method of driving the solenoid valve in consideration of such characteristics of the electromagnetic force and the urging force will be described.

FIG. 7 is a time chart showing changes with time in the current of the upper coil 85, the current of the lower coil 87, and the valve lift. The current is a drive command value given by the ECU 70. As shown in this figure, the driving of the solenoid valve is divided into three sections, a starting section, a holding section and an actual operation section. First, in the starting section, a resonance phenomenon is used to save power. That is, so that the natural vibration of the valve body is generated around the neutral position in the non-energized state, a current is alternately applied to the upper coil and the lower coil at a cycle according to the natural frequency of the spring-mass system including the plunger as a mass. . Then, the valve body gradually increases in amplitude from the neutral position, as shown in FIG. In this way, by utilizing the resonance phenomenon, it is possible to reduce the electromagnetic force at the time of starting, and hence the current for generating the electromagnetic force, and as a result, it is possible to save power at the time of starting and to reduce the circuit configuration. Is also simplified.

Finally, in the holding section, the plunger is attracted to the upper core side and the valve is closed.
In this holding section, the upper coil current flows for a longer time than the energization time in the starting section. As a result, it is possible to avoid a situation in which the plunger rebounds due to collision between the plunger and the upper core due to the excessive acceleration of the plunger, and the plunger is not sucked.
Then, from the time when the plunger is completely attracted to the time when the actual operation section starts, the minimum current (hereinafter referred to as a holding current) necessary for attracting and holding the plunger continues to flow in order to reduce extra power consumption.

In the actual operation section, as shown in FIGS. 7 (A) and 7 (B), electric currents are alternately applied to the lower coil and the upper coil to achieve the vertical operation of the valve element. That is,
When attempting to open the valve, first, the supply of the holding current to the upper coil 85 is stopped. Then, the valve body 80 is
Although the spring-mass system moves in the fully open direction by a simple vibration (free vibration), the amplitude of the valve body 80 is reduced due to the friction loss between the valve shaft 82 and the valve guide 91, the internal friction loss of the spring itself, and the like. , The current is supplied to the lower coil 87 at a certain timing because it attenuates with respect to the ideal state. The current can be divided into three, that is, an attracting current, a transition current and a holding current, as shown in FIG. That is, first, an attracting current for moving the plunger 83 is supplied. Then, a transition current that decreases at a certain temporal change rate is supplied so that the plunger 83 is attracted while the electromagnetic force (suction force) is weakened. After the plunger 83 is attracted, the minimum necessary current for holding the valve body 80 by suction, that is, the holding current is supplied.
Similarly, when attempting to close the valve from the fully open state, first, the supply of the holding current to the lower coil 87 is stopped, and the suction current, the transition current and the holding current are sequentially supplied to the upper coil 85.

[0039] In the driving method, time required for start-up of the solenoid valve (startup required time) "T ₁ -T _0" is dependent on the magnitude of the drive current during startup. FIG. 8 is a time chart exemplifying temporal changes in the upper coil current, the lower coil current, and the valve lift at the time of starting for a large drive current (A) and a small drive current (B). As shown in this figure, when the drive current is large, the electromagnetic force becomes large, so that the speed at which the amplitude of the valve lift increases increases, and as a result, the required starting time becomes short. On the other hand, on the contrary, when the drive current is small, the electromagnetic force becomes small, so that the increasing speed of the valve lift amplitude becomes small, and as a result, the required starting time becomes long.

As described above, the internal combustion engine is generally designed to have a size such that the top dead center position of the piston interferes with the fully open position of the valve in order to improve the compression ratio. That is, there is a crank angle range in which the piston and the valve element may interfere with each other depending on the valve lift.
When such a crank angle range is defined as a valve stamp area, the valve stamp area is, for example, the crank angle range as shown in FIG. 9, and the crank angle range other than the valve stamp area is referred to as a valve opening allowable period. You can
This valve stamp area is a constant crank angle range that is independent of rotational speed.

In an electromagnetically driven valve configured as a spring-mass system, the transition time T from the fully closed position to the fully open position or from the fully open position to the fully closed position does not depend on the angular velocity of the crankshaft but on the time. , T = π√ (M / K) M: Weight of movable part K: Given by spring constant, as shown in FIG. 10, it is much shorter than that of the conventional cam drive valve. Further, in the cam driven valve, the transition time does not depend on time but on the angular velocity of the crankshaft, and therefore the difference between the transition times becomes larger as the rotational speed becomes lower. As described above, it is necessary to prevent the occurrence of the valve stamp in the electromagnetically driven valve in consideration of the characteristic that the lift gradient is tight without depending on the crank angle.

FIG. 11 is a diagram showing the relationship among crank angle (crank angle after top dead center [° CA-ATDC]), piston position and valve lift. In this figure, the valve stamp area is a crank angle range from A ₂ to A _{1 in} consideration of a predetermined margin. Therefore, in order to prevent the valve stamp, the drive for moving in the valve closing direction must be started at the latest when the crank angle position reaches A ₂ . Since the time required for the valve closing operation is constant in time as described above, the crank angle position A reaching the fully closed state is
₃ changes according to the rotation speed of the crankshaft, for example,
As the rotation speed increases, A ₃
It shifts to the retard angle side from A ₃ '.

The earliest time after the top dead center the valve may be in the fully open state is when the crank angle position reaches A ₁ . Therefore, the crank angle position at which it is possible to start driving to the fully open state from the fully closed state is a crank angle position A ₀ than A ₁ corresponds to a point in time before a certain period of time, the crank angle position A ₀ It changes according to the rotational speed of the crankshaft, for example, when the rotational speed increases, as shown in the figure, the transition from a ₀ to the advance side to the a ₀ '. It should be noted that if the rotation speed becomes higher, it is possible that two straight lines indicating the transition of the lift intersect.

As can be seen from the above description, in order to prevent the valve stamp when starting the electromagnetically driven valve by utilizing the natural vibration of the spring-mass system, A ₀ is the earliest starting start time and A ₂ is The latest start end time is set. Therefore, from A ₀ to A
_The starting allowable period is up to ₂ , and the required starting time “T ₁ −T ₀ ” (denoted as T _st ) shown in FIG. 7 is set within the time range (starting allowable time) corresponding to the allowable starting period. It suffices to set the start timing T ₀ (Claims).
1, 2, 5) . Here, the allowable start time "A _{0 to} A ₂ "
Is dependent on the rotational angular speed (cranking speed) of the crankshaft at engine start, and becomes smaller as the cranking speed increases. Further, the required start time T _st depends on the drive current value of the electromagnetically driven valve and decreases as the drive current value increases. Hereinafter, a specific method of starting the solenoid valve will be described.

12 and 13 are flowcharts showing the procedure of the solenoid valve starting routine. First, in step 202, the duty ratio in the chopper circuit 98 is set to a predetermined initial value, and the starter motor 95 is driven to start cranking. Next, at step 204, the rotation speed of the crankshaft, that is, the cranking speed NE is detected based on the output of the crank angle sensor 51. Next, at step 206, it is judged if the cranking speed NE is within a predetermined range,
If the determination result is YES, the process proceeds to step 210, where N
When it is O, the process proceeds to step 208. In step 208, the duty ratio in the chopper circuit 98 is changed in order to adjust the terminal voltage of the starter motor. By such control, for example, when the cranking speed is excessively high when the drive current applied to the solenoid valve cannot be increased too much, that is, when the required starting time is too long for the allowable start time of the solenoid valve, the crank Ranking speed can be suppressed (claim 2) . After executing step 208, the process loops back to step 204.

In step 210, the cranking speed NE is determined by referring to the map as shown in FIG.
The solenoid valve drive current value I _{dr according} to the above is determined. The higher the cranking speed NE, the shorter the permissible starting time, so the drive current value I _dr is increased as shown in the figure (claim 1) . Note that the map of FIG. 14 and other maps appearing in the following description are all stored in the ROM 73 in advance. Next, at step 212, the required starting time T _st corresponding to the drive current value I _dr is obtained by referring to the map as shown in FIG. Then step 2
At 14, the required starting time _Tst is converted into the required starting time _{Ast based} on the crank angle according to the cranking speed NE. Next, at step 216, the cranking speed N
Based on E, the starting allowable period "A _0-
Determining A ₂ ". In addition, latest start end timing A ₂ is a constant value, the beginning of startup time A ₀ is longer is determined by referring to a map such as shown in FIG. 16 (claim
1, 2) .

Next, at step 218, under the condition that the required start-up period _Ast falls within the allowable start-up period "A ₀ -A ₂ ", the start-up start timing P for each solenoid valve of each cylinder is started.
Decide ₀ . There are several conceivable methods for determining the start-up start time P ₀ , which will be described later. Next, at step 220, the current crank angle position is detected based on the output of the crank angle sensor 51. Next, at step 222, it is determined whether or not one of the solenoid valves is at the start start timing. If the determination result is YES, the process proceeds to step 224, and if NO, the process loops back to step 220. Step 224
Then, the start of the electromagnetic valve, which is the start start time, is started, and the routine proceeds to step 226. In step 226, it is determined whether or not the start of all the solenoid valves has been started. If the determination result is NO, the process loops back to step 220,
If YES, this routine ends.

Next, an embodiment relating to the method for determining the starting start timing P ₀ in step 218 described above will be described. First, the first embodiment is suitable when the allowable start period “A _{0 to} A ₂ ” has a margin with respect to the required start period _Ast . That is, in the first embodiment, as shown in FIG. 17, when the problem of interference does not occur even if the start of the solenoid valve is started when the piston position is near the bottom dead center (BDC), It is intended to start the start of each solenoid valve of each cylinder in the vicinity of the bottom dead center. In this case, taking a four-cylinder engine as an example, the # 1 cylinder and the # 4 cylinder have the same piston position, and the # 3 cylinder and the # 2 cylinder have the same piston position. The state of starting the exhaust valve is, for example, as shown in FIG.

The second embodiment is effective when the allowable start period "A _{0 to} A ₂ " has no margin with respect to the required start period _Ast . That is, in the second embodiment,
As shown in FIG. 19, the start start timing P ₀ is made to coincide with the earliest start start timing A ₀ . In that case, as shown in FIG. 20, one of the four cylinders that reaches A ₀ first is selected from the four cylinders, and starting is sequentially started from that cylinder at every 180 ° CA in accordance with the ignition order. . Further, the intake stroke, the compression stroke, the explosion stroke and the exhaust stroke are carried out in that order (claim 3) .

Next, a third embodiment will be described. The third embodiment is intended to reduce the power consumption by minimizing the holding section and shortening the holding current supply time. That is, in the third embodiment, as shown in FIG. 21, the start start timing P ₀ is set so that the start is completed before the latest start end timing A ₂ by a margin. The starting deployment sequence is similar to that of the second embodiment, and its appearance is illustrated in FIG.

Next, a fourth embodiment will be described. In the fourth embodiment, as shown in FIG. 23, the start start timing P ₀ is freely set from the earliest starting state as in the second embodiment to the latest starting state as in the third embodiment. It is made possible (claims
5) . By doing so, the start of the solenoid valve can be started earlier than the corresponding cylinder, and the engine startability becomes excellent.

Finally, the fifth embodiment will be described.
In each of the above-described embodiments, the intake valve and the exhaust valve are simultaneously started in each cylinder, but it is not always necessary to do so. Therefore, in the fifth embodiment, as shown in FIG.
Performed by shifting the start of the intake valve and the start of the exhaust valve (claim
4) . As a result, the peak value of the supply current can be lowered, the required maximum current of the entire system can be suppressed, and the amount of heat generated from the solenoid valve in the same cylinder can be suppressed.

Although the embodiments of the present invention have been described above, of course, the present invention is not limited thereto, and it will be easy for those skilled in the art to devise various embodiments.

[0054]

As described above, according to the present invention,
In an internal combustion engine that uses an electromagnetically driven valve as an intake / exhaust valve, when the electromagnetically driven valve is started by utilizing the natural vibration of a spring-mass system, it is possible to reliably prevent interference between the valve element and the piston.

[Brief description of drawings]

FIG. 1 is an overall schematic diagram of an electronically controlled internal combustion engine according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a hardware configuration of an engine ECU according to the embodiment of the present invention.

FIG. 3 is a vertical cross-sectional view showing a configuration of electromagnetic valves used as an intake valve and an exhaust valve.

FIG. 4 is a diagram showing a configuration of an engine starting device.

FIG. 5 is a diagram showing a slit disk encoder.

FIG. 6 is a characteristic diagram (solid line) showing the relationship between the plunger position and the electromagnetic force (attraction force) exerted by the upper electromagnet on the plunger (solid line), and the urging force exerted by the plunger position and the pair of springs on the plunger. It is a characteristic diagram (broken line) showing the relationship with.

FIG. 7 is a time chart of an upper coil current (A), a lower coil current (B) and a valve lift (C).

FIG. 8 is a time chart exemplifying temporal changes in the upper coil current, the lower coil current, and the valve lift at the time of starting for a case where the drive current value is large (A) and a case where the drive current value is small (B).

FIG. 9 is a diagram showing a valve stamp area and a valve opening allowable period.

FIG. 10 is a diagram showing a transition time from the fully closed position to the fully open position or from the fully open position to the fully closed position for the electromagnetically driven valve and the cam driven valve.

[Fig. 11] Crank angle (Crank angle after top dead center [° CA
-ATDC]), a piston position and a valve lift.

FIG. 12 is a flowchart (1/2) showing a processing procedure of a solenoid valve starting routine.

FIG. 13 is a flowchart (2/2) showing a processing procedure of a solenoid valve starting routine.

FIG. 14 is a diagram showing a map for determining a solenoid valve drive current value I _dr according to a cranking speed NE.

FIG. 15 is a diagram showing a map defining a required starting time T _st according to a solenoid valve drive current value I _dr .

FIG. 16 is a diagram showing a map in which an earliest starting start timing A ₀ is determined according to a cranking speed NE.

FIG. 17 is a diagram for explaining a method of determining a start start timing (crank angle) P _{0 according} to the first embodiment.

FIG. 18 is a diagram showing how the intake and exhaust valves of each cylinder according to the first embodiment are started.

FIG. 19 is a diagram for explaining a method of determining a start start timing (crank angle) P _{0 according} to the second embodiment.

FIG. 20 is a diagram showing how the intake and exhaust valves of each cylinder according to the second embodiment are started.

FIG. 21 is a diagram for explaining a method of determining a start start timing (crank angle) P _{0 according} to the third embodiment.

FIG. 22 is a diagram showing a state of starting the intake and exhaust valves of each cylinder according to the third embodiment.

FIG. 23 is a diagram for explaining a method of determining a start start timing (crank angle) P _{0 according} to the fourth embodiment.

FIG. 24 is a diagram showing how the intake and exhaust valves of each cylinder according to the fifth embodiment are started.

[Explanation of symbols]

2 ... Air cleaner 4 ... Throttle body 5 ... Throttle valve 6 ... Surge tank (intake manifold) 7 ... Intake pipe 10 ... Fuel tank 11 ... Fuel pump 12 ... Fuel pipe 20 ... Cylinder (engine body) 21 ... Combustion chamber 22 ... Cooling water Passage 23 ... Piston 24 ... Intake valve 26 ... Exhaust valve 30 ... Exhaust manifold 34 ... Exhaust pipe 38 ... Catalytic converter 40 ... Air flow meter 42 ... Throttle opening sensor 43 ... Intake temperature sensor 44 ... Water temperature sensor 45 ... O ₂ sensor 51 ... Crank angle sensor 52 ... Idle switch 53 ... Vehicle speed sensor 60 ... Fuel injection valve 65 ... Spark plug 70 ... Engine ECU 71 ... CPU 72 ... System bus 73 ... ROM 74 ... RAM 75 ... A / D conversion circuit 76 ... Input interface circuit 77a , 77d ... Drive control circuit 79 ... Backup RAM 8 ... Valve element 81 ... Valve head 81a ... Valve face 82 ... Valve shaft 83 ... Plunger 84 ... Upper core 85 ... Upper coil 86 ... Lower core 87 ... Lower coil 88 ... Upper spring 89 ... Lower spring 90 ... Case 91 ... Valve guide 92 ... Internal combustion engine Intake / exhaust port 93 ... Valve seat 94 ... Battery 95 ... Starter motor 96 ... Starter pinion 97 ... Ring gear 98 ... Chopper circuit 102 ... Slit disk encoder 103 ... Emitter / receiver

Claims (5)

(57) [Claims] 1. A spring elastically supports a valve element at a neutral position to form a spring-mass system, and an electromagnetic force acts on a plunger integrated with the valve element to move the valve element to the neutral position. In the method of starting the electromagnetically driven valve of the internal combustion engine, which is displaced from the to the fully open position or the fully closed position, the valve body is moved to the fully closed position after the excitation of the natural vibration of the spring-mass system is started by the electromagnetic force. The electromagnetically driven valve is started for the required start time until it reaches and is held in the fully closed position.
Sometimes the earliest possible start time to prevent valve stamping
Starting allowance from crank angle to the end of the latest start
The start timing of the electromagnetically driven valve is set so as to be within the start allowable time corresponding to the period , and the natural vibration of the spring-mass system is detected when the crank angle position reaches the start start timing. A driving current is started to be applied to the electromagnetically driven valve in order to apply an electromagnetic force that vibrates in accordance with the number to the plunger, and further, the earliest starting start timing is set based on the detected cranking speed, and A method for starting an electromagnetically driven valve of an internal combustion engine, wherein the drive current is increased as the cranking speed is increased. 2. A valve body is elastically supported at a neutral position by a spring to form a spring-mass system, and an electromagnetic force is applied to a plunger integrated with the valve body so that the valve body is at the neutral position. In the method of starting the electromagnetically driven valve of the internal combustion engine, which is displaced from the to the fully open position or the fully closed position, the valve body is moved to the fully closed position after the excitation of the natural vibration of the spring-mass system is started by the electromagnetic force. The electromagnetically driven valve is started for the required start time until it reaches and is held in the fully closed position.
Sometimes the earliest possible start time to prevent valve stamping
Starting allowance from crank angle to the end of the latest start
The start timing of the electromagnetically driven valve is set so as to be within the start allowable time corresponding to the period , and the natural vibration of the spring-mass system is detected when the crank angle position reaches the start start timing. A driving current is started to be applied to the electromagnetically driven valve in order to apply an electromagnetic force that vibrates in accordance with the number to the plunger, and further, the earliest starting start timing is set based on the detected cranking speed, and , The electromagnetic drive
The drive current given to the valve cannot be increased too much.
If the cranking speed is too high
Is adjusted so that the cranking speed becomes smaller as the drive current becomes smaller, and a method for starting an electromagnetically driven valve of an internal combustion engine. 3. The internal combustion engine comprises a plurality of cylinders,
After the application of the drive current is started from the cylinder whose crank angle position has reached the start start timing and the valve body is held in the fully closed position, the electromagnetically driven valve is opened and closed in response to the movement of the piston. The method for starting an electromagnetically driven valve for an internal combustion engine according to claim 1 or 2, wherein the cylinders are sequentially deployed in the next ignition sequence. 4. The cylinder according to claim 1, wherein a plurality of electromagnetically driven valves are provided in one cylinder, and start timings of the plurality of electromagnetically driven valves are shifted and set. Method for starting an electromagnetically driven valve of an internal combustion engine according to claim 1. 5. A valve body is elastically supported at a neutral position by a spring to form a spring-mass system, and an electromagnetic force is applied to a plunger integrated with the valve body so that the valve body is at the neutral position. In the method of starting the electromagnetically driven valve of the internal combustion engine, which is displaced from the to the fully open position or the fully closed position, the valve body is moved to the fully closed position after the excitation of the natural vibration of the spring-mass system is started by the electromagnetic force. The electromagnetically driven valve is started for the required start time until it reaches and is held in the fully closed position.
Sometimes the earliest possible start time to prevent valve stamping
Starting allowance from crank angle to the end of the latest start
The start timing of the electromagnetically driven valve is set so as to be within the start allowable time corresponding to the period , and the natural vibration of the spring-mass system is detected when the crank angle position reaches the start start timing. the electromagnetic force a vibration corresponds to the number begins to apply a driving current in order to act on said plunger to said electromagnetically driven valve, further wherein the starting start time, the startup required time
A method for starting an electromagnetically driven valve for an internal combustion engine, wherein the interval is freely set from the earliest time to the latest time in a crank angle range within the allowable start time .