JPH11280432A - Control device for solenoid valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent increase in the driving force required for opening an intake valve in a control device for a solenoid valve which controls the solenoid valve composed as the intake valve for an internal combustion engine. SOLUTION: An internal combustion engine is equipped with a solenoid driven valve. The valve element of the solenoid driven valve composes an intake valve. An ECU detects or estimates the intake pressure PM and cylinder internal pressure PC of the internal combustion engine. At a point of time when exhaust stroke is finished, the cylinder internal pressure PC is high in comparison with the intake pressure PM. The ECU retains the intake valve in a valve closing condition even passing a top dead center and closes the intake valve at a point of time when the cylinder internal pressure PC is lowered to the intake pressure PM or below.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a solenoid valve, and more particularly to a control device for a solenoid valve suitable for controlling a solenoid valve configured as an intake valve of an internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, Japanese Patent Laid-Open Publication No.
As disclosed in Japanese Patent No. 913, an electromagnetically driven valve is known. The conventional electromagnetically driven valve includes a valve body that functions as an intake valve or an exhaust valve of an internal combustion engine, and a plunger connected to the valve body. The valve body and the plunger can be displaced in the axial direction of the valve body. Hereinafter, the valve body and the plunger are referred to as a movable part.

A first electromagnet and an upper spring are disposed above the plunger. A second electromagnet and a lower spring are provided below the plunger. The plunger is held at a neutral position between the first electromagnet and the second electromagnet by the upper spring and the lower spring. Each of the first electromagnet and the second electromagnet generates an electromagnetic force for attracting the plunger when an exciting current is supplied.

According to the above-mentioned conventional electromagnetically driven valve, the movable portion can be displaced toward the first electromagnet by supplying an exciting current to the first electromagnet. Further, by supplying an exciting current to the second electromagnet, the movable portion can be displaced toward the second electromagnet. Therefore, according to the above-mentioned conventional electromagnetically driven valve, the exhaust valve or the intake valve can be opened and closed at an arbitrary timing by supplying an exciting current to the first electromagnet and the second electromagnet at an appropriate timing.

[0005]

By the way, the intake valve of the internal combustion engine is opened after the end of the exhaust stroke in order to draw air from the intake pipe into the combustion chamber. The exhaust stroke is a stroke for discharging combustion gas and unburned gas generated in the combustion stroke. Therefore, in the exhaust stroke, the in-cylinder pressure is higher than the atmospheric pressure, and is maintained at a value near the atmospheric pressure even at the end of the exhaust stroke. On the other hand, the pressure in the intake pipe (that is, the intake pressure) is always maintained at a negative pressure corresponding to the throttle opening. Therefore, at or immediately after the end of the exhaust stroke, a differential pressure is generated between the in-cylinder pressure and the intake pressure in a direction that prevents the intake valve from being displaced toward the valve opening side. Assuming that the intake valve is opened in a state where such a differential pressure is generated,
It is necessary to apply an extra driving force to the intake valve to counter the differential pressure. As a result, the exciting current to be supplied to the electromagnet increases, and the power consumption of the electromagnetically driven valve increases. In order to avoid such inconvenience, it is desirable to determine the timing for opening the intake valve in consideration of the in-cylinder pressure and the intake pressure.

However, in the above-mentioned conventional electromagnetically driven valve, the above-mentioned problem caused by the pressure difference between the in-cylinder pressure and the intake pressure is not taken into consideration. No consideration was given to setting the timing. The present invention has been made in view of the above points, and by setting the timing of opening the intake valve based on the in-cylinder pressure and the intake pressure, the driving force required to open the intake valve is reduced. It is an object of the present invention to provide an electromagnetic valve control device capable of preventing an increase.

[0007]

The above object is achieved by the present invention.
A solenoid valve control device that opens and closes at a predetermined timing an electromagnetic valve including a valve body that functions as an intake valve of an internal combustion engine and an electromagnet that drives the valve body to the valve opening side, as described in Control of an electromagnetic valve comprising: a differential pressure detecting unit that detects or estimates a differential pressure between an atmospheric pressure and an in-cylinder pressure; and a valve opening timing determining unit that determines a timing at which the valve element is opened based on the differential pressure. Achieved by the device.

In the present invention, the control device for the electromagnetic valve opens and closes the intake valve of the internal combustion engine at a predetermined timing. When the intake valve opens, it is displaced in a direction to enter the combustion chamber of the internal combustion engine. Therefore, in order to open the intake valve in a state where the pressure in the combustion chamber, that is, the in-cylinder pressure is higher than the intake pressure,
It is necessary to apply extra driving force to the intake valve to oppose the pressure difference. On the other hand, in the present invention, the valve opening timing determining means determines the valve opening timing of the intake valve based on the pressure difference between the in-cylinder pressure and the intake pressure. Therefore, the intake valve can be opened in a state where the differential pressure does not hinder the displacement of the intake valve toward the valve opening side. Therefore, according to the present invention, it is not necessary to apply the above-mentioned extra driving force to the intake valve when opening the intake valve.

According to a second aspect of the present invention, in the control apparatus for an electromagnetic valve according to the first aspect, the valve opening timing determining means determines that the in-cylinder pressure is lower than the intake pressure. This is achieved by a control device for an electromagnetic valve that permits opening of the valve only when: In the present invention,
The valve opening timing determining means permits the valve body to open only when the in-cylinder pressure is lower than the intake pressure, thereby opening the intake valve in a state where the in-cylinder pressure is higher than the intake pressure. It is prevented from being valved. Therefore, according to the present invention, an increase in the driving force to be applied to the intake valve when the valve is opened is reliably prevented.

[0010]

FIG. 1 is a block diagram of an internal combustion engine to which a solenoid valve control device according to an embodiment of the present invention is applied. The system according to the present embodiment is controlled by the ECU 10. The internal combustion engine includes a cylinder block 12.
Inside the cylinder block 12, a cylinder 14 and a water jacket 16 are formed. The internal combustion engine has a plurality of cylinders. FIG. 1 shows one cylinder 14 among a plurality of cylinders.

A piston 18 is provided inside the cylinder 14. The piston 18 can slide inside the cylinder 14 in the vertical direction in FIG. A cylinder head 20 is fixed to an upper portion of the cylinder block 12. In the cylinder head 20, an intake port 22 and an exhaust port 24 are formed for each cylinder.

The bottom of the cylinder head 20, the piston 18
And a side wall of the cylinder 14 define a combustion chamber 26. The above-described intake port 22 and exhaust port 24 both open to the combustion chamber 26. Intake port 2
2 and the opening end on the combustion chamber 26 side and the exhaust port 24
Valve seats 28 and 30 are formed at the opening ends of the combustion chamber 26 side.

The cylinder head 20 has electromagnetically driven valves 38 and 40 incorporated therein. The electromagnetically driven valve 38 has a valve body 42
It has. The valve body 42 functions as an intake valve of the internal combustion engine. That is, the valve body 42 blocks the space between the intake port 22 and the combustion chamber 26 by seating on the valve seat 28, and separates the valve body 42 from the intake port 22 and the combustion chamber 26 by separating from the valve seat 28. Is made conductive. Hereinafter, the valve body 42 is referred to as an intake valve 42. On the other hand, the electromagnetically driven valve 4
0 has a valve body 44. The valve body 44 functions as an exhaust valve of the internal combustion engine. That is, the valve body 44 is seated on the valve seat 30 so that the exhaust port 24 and the combustion chamber 2
6 and is separated from the valve seat 30 so that the exhaust port 24 and the combustion chamber 26 are electrically connected. Hereinafter, the valve body 44 is referred to as an exhaust valve 44.

The electromagnetically driven valves 38 and 40 have the same configuration. Hereinafter, the configuration and operation of the electromagnetically driven valve 38 will be described as a representative example thereof with reference to FIG. FIG. 2 is a cross-sectional view illustrating the entire configuration of the electromagnetically driven valve 38. As shown in FIG. 2, the intake valve 42 is connected to a valve shaft 45. The valve shaft 45 is held so as to be displaceable in the axial direction by a valve guide 46 fixed inside the cylinder head 20. The electromagnetically driven valve 38 also has a plunger holder 48 fixed to the upper end of the valve shaft 45. The plunger holder 48 is a rod-shaped member made of a non-magnetic material. At the lower end of the plunger holder 48,
The lower retainer 50 is fixed. Lower retainer 50
A lower spring 52 is provided at the lower part of the lower part. The lower end of the lower spring 52 is in contact with the cylinder head 20. The lower spring 52 urges the lower retainer 50 and the plunger holder 48 upward in FIG.

An upper retainer 54 is fixed to the upper end of the plunger holder 48. Apparitainer 54
The lower end of the upper spring 56 is in contact with the upper part of the upper part. A cylindrical upper cap 57 is provided around the upper spring 56 so as to surround the outer periphery thereof. The upper end of the upper spring 56 is in contact with an adjustment bolt 58 screwed to the upper cap 57. The upper spring 56 urges the retainer 54 and the plunger holder 48 downward in FIG.

A plunger 60 is joined to the outer periphery of the plunger holder 48. The plunger 60 is an annular member made of a soft magnetic material. Above the plunger 60, a first electromagnetic coil 62 and a first core 64 are provided. Further, below the plunger 60, a second electromagnetic coil 66 and a second core 68 are provided. First
The core 64 and the second core 68 are both members made of a magnetic material. The plunger holder 48 holds the first core 6
It is slidably held at the center of the fourth and second cores 68.

An outer cylinder 74 is provided around the outer periphery of the first core 64 and the second core 68. The first core 64 and the second core 68 are held by the outer cylinder 74 so that a predetermined interval is secured between them. The above-described upper cap 57 is fixed to the upper end surface of the first core 64. The adjuster bolt 58 described above is adjusted so that the neutral position of the plunger 60 is at the center between the first core 64 and the second core 68.

First electromagnetic coil 62 and second electromagnetic coil 6
Reference numeral 6 is connected to a drive circuit (not shown). The drive circuit supplies a predetermined exciting current to each of the first electromagnetic coil 62 and the second electromagnetic coil 66 according to a command signal given from the ECU 10. In the electromagnetically driven valve 38, when the exciting current is not supplied to the first electromagnetic coil 62 and the second electromagnetic coil 66, the plunger 60 is maintained at the neutral position, that is, the center of the first core 64 and the second core 68. Is done. When an exciting current is supplied to the first electromagnetic coil 62 while the plunger 60 is maintained at the neutral position, an electromagnetic force is generated to attract the plunger 60 to the first core 64 side.

When the above-mentioned electromagnetic force acts on the plunger 60, the intake valve 42 is displaced upward together with the plunger 60 in FIG. The intake valve 42 is seated on the valve seat 28 by being displaced as described above.
Hereinafter, the state where the intake valve 42 is seated on the valve seat 28 is referred to as a closed state, and the position of the intake valve 42 at that time is referred to as a closed position.

When the exciting current supplied to the first electromagnetic coil 62 is interrupted while the intake valve 42 is maintained at the closed position, the electromagnetic force acting on the plunger 60 disappears. When the electromagnetic force acting on the plunger 60 disappears, the plunger 60 is displaced downward in FIG. 1 by being urged by the upper spring 56. When the displacement of the plunger 60 reaches a predetermined value,
When an appropriate exciting current is supplied to the second electromagnetic coil 66,
This time, a suction force for sucking the plunger 60 toward the second core 68, that is, a suction force for displacing the intake valve 42 downward in FIG. 2 is generated.

When the above-mentioned suction force acts on the plunger 60, the plunger 60 is displaced downward in FIG. 2 together with the intake valve 42 against the urging force of the lower spring 52. The displacement of the intake valve 42 continues until the plunger 60 contacts the second core 68. Hereinafter, a state in which the plunger 60 is in contact with the second core 68 is referred to as a valve open state, and a position of the intake valve 42 at that time is referred to as a valve open position.

As described above, according to the electromagnetically driven valve 38, by supplying a predetermined exciting current to the first electromagnetic coil 62, the intake valve 42 can be displaced toward the valve closing position, and the second electromagnetic By supplying a predetermined exciting current to the coil 66, the intake valve 42 can be displaced toward the valve opening position. Therefore, according to the electromagnetically driven valve 38, the excitation current is alternately supplied to the first electromagnetic coil 62 and the second electromagnetic coil 66, so that the intake valve 42 is repeatedly switched between the open position and the closed position. Can be reciprocated.

In this embodiment, the electromagnetically driven valve 40 including the exhaust valve 44 operates in the same manner as the above-described electromagnetically driven valve 38. Therefore, according to the present embodiment, the electromagnetically driven valves 38, 4
The ECU 10 applies a command signal to the drive circuit so that the exciting current is alternately supplied at appropriate timing to the first electromagnetic coil 62 and the second electromagnetic coil 66 included in the intake valve 42, respectively. And exhaust valve 44
Can be driven to open and close at any timing.

As shown in FIG. 1, the internal combustion engine has an intake manifold 80. The intake manifold 80 includes a plurality of branch pipes that communicate the surge tank 82 and each intake port 22. Each branch pipe is provided with a fuel injection valve 83. The fuel injection valve 83 injects fuel into the branch pipe according to a command signal given from the ECU 10. An intake pipe 84 communicates upstream of the surge tank 82. A throttle valve 86 is provided in the intake pipe 84. The throttle valve 86 is configured to operate in conjunction with the accelerator pedal. In the vicinity of the throttle valve 86, a throttle opening sensor 87 is provided. The output signal of the throttle opening sensor 87 is supplied to the ECU 10. The ECU 10 detects the throttle opening based on the output signal of the throttle opening sensor 87.

An intake pressure sensor 88 is disposed downstream of the throttle valve 86 in the intake pipe 84. The output signal of the intake pressure sensor 88 is supplied to the ECU 10. Based on the output signal of the intake pressure sensor 88, the ECU 10 controls the intake system, that is, the pressure inside the intake pipe 84 downstream of the throttle valve 86, the surge tank 82, the intake manifold 80, and the intake port 22 (hereinafter, intake pressure). PM). An air cleaner 90 communicates with the upstream end of the intake pipe 84. Therefore, the outside air filtered by the air cleaner 90 flows into the intake pipe 84.

An exhaust passage 92 communicates with the exhaust port 24 of the internal combustion engine. A catalyst device 94 is provided in the exhaust passage 92.
The muffler 96 is in communication with the other. The exhaust gas discharged from the internal combustion engine is purified by the catalyst device 94,
After being silenced by the muffler 96, the exhaust gas is discharged into the atmosphere. The internal combustion engine also includes a crank angle sensor 92. The output signal of the crank angle sensor 92 is supplied to the ECU 10. The ECU 10 includes a crank angle sensor 92
, The crank angle CA and the rotation speed Ne of the internal combustion engine are detected.

In this embodiment, the operation state of the internal combustion engine is maintained by opening and closing the intake valve 42 and the exhaust valve 44 and injecting fuel by the fuel injection valve 84 at a timing corresponding to the crank angle CA. You. In the exhaust stroke of the internal combustion engine, the piston 1 is opened with the exhaust valve 44 opened.
8 is displaced from the bottom dead center side to the top dead center side, and the burned gas and the unburned gas generated in the combustion stroke are discharged from the combustion chamber 26 to the exhaust port 24. Then, in the intake stroke following the exhaust stroke, the piston 18 is displaced from the top dead center side to the bottom dead center side with the intake valve 42 opened, so that the fuel injection valve 8 is opened.
The mixture of fuel and air injected by the fuel injection port 3
2 into the combustion chamber 26.

At the start of the exhaust stroke, the pressure inside the combustion chamber 26 (hereinafter referred to as the in-cylinder pressure PC) is high because combustion gas generated in the combustion stroke exists in the combustion chamber 26. . Then, as the exhaust stroke proceeds, the in-cylinder pressure P
C gradually decreases, and at the end of the exhaust stroke, that is, when the piston 18 reaches the top dead center, the in-cylinder pressure PC becomes substantially equal to the atmospheric pressure. On the other hand, in the intake port 22,
Outside air is drawn in while being throttled by the throttle valve 86. For this reason, the intake pressure PM is always maintained at a negative pressure of a magnitude corresponding to the opening of the throttle valve 86.

That is, at the end of the exhaust stroke, the in-cylinder pressure PC is higher than the intake pressure PM. Assuming that the intake valve 42 is opened in this state, the intake valve 4
No. 2 is displaced toward the inside of the combustion chamber 26 against the pressure difference between the in-cylinder pressure PC and the intake pressure PM. in this case,
It is necessary to apply an extra driving force to the intake valve 42 to oppose the differential pressure. As a result, the exciting current to be supplied to the second electromagnetic coil 66 to drive the intake valve 42 to the valve opening side increases, and the power consumption of the electromagnetic drive valve 38 increases.

When the intake valve 42 is opened while the in-cylinder pressure PC is higher than the intake pressure PM, the burned gas present in the combustion chamber 26 flows back to the intake port 22 side. When such backflow occurs, components contained in the burned gas adhere to the inside of the intake port 22, the intake manifold 80, the surge tank 82, the intake pipe 84, etc., and contaminate them.

On the other hand, in the internal combustion engine of this embodiment, the timing for opening the intake valve 42 is appropriately determined based on the in-cylinder pressure PC and the intake pressure PM, so that the intake valve 4 is opened.
It is characterized in that it is possible to prevent an increase in driving force to be applied to the fuel cell 2 and to prevent backflow of burned gas from the combustion chamber 26 to the intake system side. Hereinafter, such a characteristic portion of the present embodiment will be described.

FIG. 3 shows the opening / closing timing of the exhaust valve 44 and the intake valve 42 with respect to the displacement of the piston 18 in the combustion chamber 26
It is illustrated along with changes in the internal pressure (that is, the in-cylinder pressure) and the intake pressure PM. 3A shows the open / closed state of the exhaust valve 44 and the intake valve 42, and FIG. 3B shows the in-cylinder pressure PC by a solid line and the intake pressure PM by a broken line. 3A and 3B, the piston 18
Is represented by the crank angle CA.

As shown in FIG. 3A, during the exhaust stroke, the exhaust valve 44 is kept open, and is closed in synchronization with the piston 18 reaching the top dead center. As shown by the solid line in FIG. 3B, at the start of the intake stroke, the in-cylinder pressure PC is in a high pressure state. Then, as the piston 18 is displaced toward the top dead center, the in-cylinder pressure PC gradually decreases. At the end of the exhaust stroke, that is, when the piston 18 reaches the top dead center, the in-cylinder pressure PC becomes the atmospheric pressure. Is almost equal to On the other hand, as described above, the intake pressure PM becomes a negative pressure having a magnitude corresponding to the opening degree of the throttle valve 86, and as shown by a broken line in FIG. 3B, the intake pressure PM is substantially constant throughout the exhaust stroke and the intake stroke. It is kept at negative pressure.

Therefore, when the piston 18 reaches the top dead center, a relatively large differential pressure ΔP is generated between the in-cylinder pressure PC and the intake pressure PM. Therefore, as shown by the broken line in FIG. 3A, if the intake valve 42 is opened immediately after or immediately after the piston 18 reaches the top dead center, the intake valve 42 is affected by the differential pressure ΔP. As described above, it is necessary to apply an extra driving force to the combustion chamber 26 and to cause a backflow of the burned gas from the combustion chamber 26 to the intake system side.

On the other hand, in the present embodiment, FIG.
As shown by the solid line, even when the piston 18 has passed the top dead center, the intake valve 42 is kept in the closed state, and the in-cylinder pressure PC becomes the intake pressure PM.
The intake valve 42 is opened at the time when the pressure falls below the threshold. That is, when the piston 18 reaches the top dead center and the exhaust valve 4
When the intake valve 42 is kept closed after the valve 4 is closed, the combustion chamber 26 is shut off from both the intake port 22 and the exhaust port 24. In this state, when the piston 18 is displaced from the top dead center to the bottom dead center, the volume in the combustion chamber 26 increases, and as shown by a solid line in FIG. It decreases to the compression side.

Therefore, in this embodiment, as shown by the solid line in FIG. 3A, the differential pressure ΔP between the in-cylinder pressure PC and the intake pressure PM
Is substantially zero (the crank angle CA is as shown in FIG. 3 (B)
(When the position θ ₀ shown in FIG. ₂ is reached), the intake valve 42 is opened. By opening the intake valve 42 at such timing, the intake valve 42 is driven to the valve opening side in a state where the displacement of the intake valve 42 is not hindered by the differential pressure between the in-cylinder pressure PC and the intake pressure PM. can do. Therefore, according to the present embodiment, it is possible to prevent an increase in the driving force required to open the intake valve 42, and as a result, the electromagnetically driven valve 3
8 can save power. Further, since the intake valve 42 is not opened when the in-cylinder pressure PC is higher than the intake pressure PM, backflow of burned gas from the combustion chamber 26 to the intake system side can be prevented.

When the intake valve 42 is open, the combustion chamber 26 and the intake port 22 communicate with each other. Therefore, when the intake valve 42 is opened, the in-cylinder pressure PC thereafter becomes the intake pressure P
It is kept approximately equal to M. In this embodiment, the intake pressure PM can be detected based on the output signal of the intake pressure sensor 88. On the other hand, the internal pressure P
No sensor for detecting C is provided. Therefore, in this embodiment, the in-cylinder pressure PC is estimated by the following method. Hereinafter, a method of estimating the in-cylinder pressure PC in the present embodiment will be described.

As described above, when the intake valve 42 is kept closed after the piston 18 reaches the top dead center, the combustion chamber 2
6 increases its volume while being shut off from both the intake port 22 and the exhaust port 24. In this case, after the piston 18 reaches the top dead center, the intake valve 42
During the period until the valve is opened, the gas in the combustion chamber 26 undergoes adiabatic expansion. Therefore, the cylinder pressure PC and the volume of the combustion chamber 26 when the crank angle CA exceeds the top dead center by θ are PC (θ) and V (θ), respectively, and the piston 18 is at the top dead center. Assuming that the in-cylinder pressure PC and the volume of the combustion chamber 26 are PC0 and V0, respectively, the following adiabatic expansion equation is established.

PC ₀ · V ₀ ^K = PC (θ) · V (θ) ^K (1) where K is the specific heat ratio of the gas present in the combustion chamber 26, and It is about 1.29. In the equation (1), V ₀ takes a constant value according to the configuration of the internal combustion engine. Further, since there is a certain relationship between θ and V (θ) according to the configuration of the internal combustion engine, if θ is specified, V
(Θ) is uniquely determined. Further, PC ₀ can be considered to be approximately equal to atmospheric pressure. Therefore, PC (θ)
Can be obtained by the following equation using these known V ₀ , PC ₀ , and V (θ).

PC (θ) = PC ₀ · (V ₀ / V (θ)) ^K (2) The in-cylinder pressure PC when the piston 18 is at the top dead center
₀ (hereinafter referred to as the back pressure PC ₀ ) can be approximately regarded as the atmospheric pressure as described above, but more precisely, the rotation speed Ne of the internal combustion engine and the load (throttle opening Degree). That is, between the back pressure P ₀ and the rotation speed Ne and the throttle opening, as Ne is higher,
Further, as the throttle opening is large, there is a relation as PC ₀ becomes high. Therefore, by determining the back pressure PC ₀ based on the rotation speed Ne and the throttle opening, the in-cylinder pressure PC (θ) can be estimated with higher accuracy.

By the above method, the cylinder pressure PC (θ) at each position after the piston 18 has passed the top dead center can be estimated. Then, the estimated in-cylinder pressure PC (θ) is
The intake valve 42 is opened when the intake pressure PM detected by the intake pressure sensor 88 falls below the predetermined value. As described above, the intake valve 42 is caused by the pressure difference ΔP between the in-cylinder pressure PC and the intake pressure PM. Can be prevented from increasing, and the burned gas can be prevented from flowing back from the combustion chamber 26 to the intake system side.

When the in-cylinder pressure PC is higher than the intake pressure PM, even if the intake valve 42 is opened, the combustion chamber 2
6 cannot inhale air. Therefore, even if the opening timing of the intake valve 42 is delayed until the in-cylinder pressure PC falls below the intake pressure PM as in the present embodiment, the operation of the internal combustion engine is not affected at all. The above functions of the system according to the present embodiment are realized by the ECU 10 executing a predetermined routine. Hereinafter, ECU
The contents of the routine executed by 10 will be described. FIG.
Is used to control the opening and closing of the intake valve 42 in this embodiment.
5 is a flowchart of an example of a routine executed by the CU 10. The routine shown in FIG. 4 is a regular interruption routine executed at predetermined time intervals.

When the routine shown in FIG. 4 is started, first, the process of step 100 is executed. Step 10
At 0, it is determined whether or not the intake valve 42 is currently open. As a result, if it is determined that the intake valve 42 is open, in step 102, the intake valve 42
It is determined whether or not it is time to close the valve. As a result, if it is the timing to close the intake valve 42, a process for closing the intake valve 42 in step 104, specifically, the first electromagnetic coil 62 of the electromagnetic drive valve 38.
After the processing for supplying the exciting current to the CPU is performed, the current routine ends. On the other hand, if it is not the timing to close the intake valve 42 in step 102, the current routine ends without performing any processing thereafter.

In step 100, the intake valve 42
If it is determined that is not opened, the process of step 106 is executed next. In step 106, the crank angle CA is detected based on the output signal of the crank angle sensor 92. When the process of step 106 is completed, the process of step 108 is executed next. In step 108, it is determined whether or not the crank angle CA corresponds to the intake stroke. As a result, when it is determined that the crank angle CA does not correspond to the intake stroke, it is determined that the intake valve 42 should not be opened, and thereafter, this routine ends without performing any processing. . On the other hand, if it is determined in step 108 that the crank angle CA corresponds to the intake stroke, a process for determining the valve opening timing of the intake valve 42 is executed in subsequent step 110 and subsequent steps.

In step 110, the intake pressure PM is detected based on the output signal of the intake pressure sensor 88. When the process of step 110 is completed, the process of step 112 is performed next. In step 112, an estimation calculation of the in-cylinder pressure PC (θ) is performed based on the above equation (2).
The ECU 10 stores therein a table indicating the relationship between the amount of elapsed θ from the top dead center of the crank angle CA and the volume V (θ) of the combustion chamber 26. And the ECU 10
Determines V (θ) by referring to this table when estimating PC (θ). Step 11
2 is completed, next, at step 114, the differential pressure ΔP between the in-cylinder pressure PC (θ) and the intake pressure PM =
After PC (θ) -PM is calculated, next at step 116
Is performed.

At step 116, it is determined whether or not the pressure difference ΔP is negative. As a result, if ΔP <0 holds, it is determined that it is time to open the intake valve 42, and the process of step 118 is executed next. In step 118, a process for opening the intake valve 42, specifically, a process for supplying an exciting current to the second electromagnetic coil 66 of the electromagnetically driven valve 38 is executed. Step 11
When the process of No. 8 is completed, the current routine is completed. On the other hand, if ΔP <0 is not established in step 116, the current routine is terminated without opening the intake valve 42.

According to the above routine, the differential pressure ΔP (= P
The intake valve 42 is opened only when C (θ) -PM) is negative. Therefore, according to the system of the present embodiment, as described above, it is possible to prevent the driving force required to open the intake valve 42 from increasing, and to prevent the burned gas from flowing backward from the combustion chamber 26 to the intake system. Can be prevented. In the above embodiment, when the ECU 10 executes the processing of steps 110 to 114 of the routine shown in FIG. 4, the differential pressure detecting means described in the claims makes it possible for the ECU 10 to execute the processing of step 116. The valve opening timing determining means described in the claims is realized respectively.

In the above embodiment, the internal combustion engine is provided with the intake pressure sensor 88, and the intake pressure PM is detected based on the output signal. However, the present invention is not limited to this, and can be applied to an internal combustion engine of a type including an air flow meter for detecting the flow rate Qa of air taken into the intake pipe, instead of the intake pressure sensor. In this case, the air flow rate Qa, the intake pressure P
Since a certain relationship is established between M and the rotation speed Ne of the internal combustion engine, the intake pressure PM may be estimated based on the air flow rate Qa and the rotation speed Ne. Alternatively, since the air flow rate Qa changes according to the throttle opening, the intake pressure PM may be estimated based on the throttle opening and the rotation speed Ne.

In the above embodiment, the cylinder pressure PC
Is estimated using the equation (2). However, the present invention is not limited to this, and a pressure sensor is provided for each cylinder of the internal combustion engine, and the in-cylinder pressure PC is directly detected based on an output signal thereof. It may be. Alternatively, a pressure sensor may be provided for only one cylinder to detect the in-cylinder pressure of that cylinder, and the in-cylinder pressure PC of another cylinder may be estimated using the detected value and the crank angle relationship between the cylinders. Good.

Further, in the above embodiment, the intake valve 42 is opened when the differential pressure ΔP becomes negative. However, the present invention is not limited to this, and the differential pressure ΔP
However, at the time when it is determined that the driving force required to drive the intake valve 42 to the valve opening side and that the backflow of the burned gas from the combustion chamber 26 to the intake system has decreased to a level that does not cause a problem. Alternatively, the intake valve 42 may be opened.

[0051]

As described above, according to the first and second aspects of the present invention, the intake valve is operated in a state where the differential pressure between the in-cylinder pressure and the intake pressure does not hinder the displacement of the intake valve toward the valve opening side. The valve can be opened. Therefore, according to the present invention, it is possible to prevent an increase in driving force required for opening the intake valve.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an internal combustion engine to which a control device for an electromagnetic valve according to an embodiment of the present invention is applied.

FIG. 2 is an overall configuration diagram of an electromagnetically driven valve provided in the internal combustion engine.

FIG. 3A is a diagram showing a relationship between a crank angle CA and an open / closed state of an exhaust valve and an intake valve. (B) is a diagram showing the relationship between the crank angle CA and the in-cylinder pressure PC and the intake pressure PM.

FIG. 4 is a flowchart of an example of a routine executed by an ECU to open and close an intake valve in the embodiment.

[Explanation of symbols]

 10 ECU 38 Electromagnetically driven valve 42 Intake valve 88 Intake pressure sensor

Claims (2)

[Claims] 1. An electromagnetic valve control device for opening and closing at a predetermined timing an electromagnetic valve including a valve body functioning as an intake valve of an internal combustion engine and an electromagnet for driving the valve body to a valve opening side. A differential pressure detecting unit that detects or estimates a differential pressure between an atmospheric pressure and an in-cylinder pressure; anda valve opening timing determining unit that determines a timing at which the valve element is opened based on the differential pressure. Control device for the solenoid valve. 2. The electromagnetic valve control device according to claim 1, wherein the valve opening timing determining means permits the valve body to open only when the in-cylinder pressure is lower than the intake pressure. A control device for a solenoid valve.