JP3141670B2 - Valve drive device for internal combustion engine and initial position setting method for valve body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve driving apparatus for an internal combustion engine and a method for setting an initial position of a valve element. The present invention relates to a method for setting an initial position of a valve body.

[0002]

2. Description of the Related Art Conventionally, there has been widely known an actuator configured to obtain a desired displacement by using an electromagnetic force generated when a predetermined current is supplied to an electromagnetic coil. For example, a core that constitutes a magnetic circuit having one end opened around the electromagnetic coil is provided, a movable member made of a magnetic material is opposed to the opening, and a spring that acts in a direction separating the movable member from the core is provided. The configuration provided is known as a typical example.

According to such a configuration, when the power supply to the electromagnetic coil is stopped, the movable element is urged by the spring and held at a predetermined position separated from the core, while the power supply to the electromagnetic coil is stopped. Then, the mover is attracted to the core side to form a magnetic closed circuit having a smaller magnetic resistance by the core and the mover. Therefore, when the energized state of the electromagnetic coil is controlled, as a result, a predetermined displacement occurs in the mover, and the function as an actuator is secured.

By the way, the current I flowing when a predetermined voltage e is applied to the electromagnetic coil can be expressed as follows, where R is the resistance value of the electromagnetic coil and L is the self inductance. “j” is an imaginary unit, “ω” is e
Is shown).

I = e / (R + jωL) (1) On the other hand, the self-inductance L of the electromagnetic coil is a characteristic value determined by N, the number of turns of the electromagnetic coil, and magnetic resistance of a magnetic circuit surrounding the electromagnetic coil. Then, it can be expressed as follows.

L = K · N ² (2) Therefore, when the mover is displaced in the actuator having the above-described configuration and the magnetic resistance of the magnetic circuit surrounding the electromagnetic coil changes accordingly, the characteristic is thereby changed. The value K is
That is, the self inductance L of the electromagnetic coil changes,
The relationship between e and I will change.

Therefore, if the self-inductance L of the electromagnetic coil can be detected based on the relationship between e and I, the displacement state of the mover constituting the actuator can be detected from the value. No. 122253 discloses a configuration of an actuator that detects a displacement amount according to such a principle.

[0008]

However, the conventional actuator described above detects the displacement of the mover by focusing on the fact that the self-inductance L of the electromagnetic coil that generates the electromagnetic force changes with the displacement of the mover. Is what you do. At this time, the self-inductance L is proportional to the square of the winding N as described above. When the number of turns N is relatively small, the value of L is relatively small, and the amount of change is relatively small.

For this reason, when the number of turns N is small due to the electromagnetic force and the like required for the electromagnetic coil, the above-described conventional device cannot accurately detect the displacement of the mover. Had a problem.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has been made in consideration of the above-described problems, and has a large number of turns in a small space using a small-diameter winding coaxially with an electromagnetic coil for generating an electromagnetic force. It is an object of the present invention to provide a valve drive device for an internal combustion engine which is provided with a coil and detects the amount of displacement of an actuator based on a change in self-inductance of the displacement detection coil.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to provide a valve driving device for an internal combustion engine that drives a valve element of an internal combustion engine with an electromagnetic force, the driving coil generating an electromagnetic force for driving the valve element, A displacement detection coil formed by winding a winding having a smaller diameter than the winding of the drive coil a number of times greater than the number of turns of the drive coil and coaxially with the drive coil; and the displacement detection changing with the displacement of the valve element. Based on the self-inductance of the coil,
This is achieved by a valve driving device for an internal combustion engine having a displacement amount detecting means for detecting a displacement amount of the valve element.

Further, in the valve driving device for an internal combustion engine having the above-mentioned structure, a capacitor is provided between both terminals of the displacement detection coil and charges an electric charge according to an electromotive force generated in the detection coil. A valve drive device for an internal combustion engine including a switch circuit for controlling energization of the internal combustion engine is effective for producing a high voltage with a simple configuration.

Further, a first and a second drive coil arranged at a predetermined distance from each other in the moving direction of the valve element to drive the valve element, and a winding of the first and second drive coils is provided. A first and a second displacement detection coil formed by winding a small-diameter winding more than the number of turns of the first and second drive coils and coaxially with the first and second drive coils, respectively; A displacement amount detection unit that detects a displacement amount of the valve body based on a self-inductance of the first and second displacement detection coils that changes with displacement of the body; and a first and second drive coil. When no electromagnetic force is generated, a predetermined current is supplied to one of the first and second drive coils and an elastic member that supports the valve element between the first and second drive coils. After applying a displacement to the valve body and stopping this energization A drive means for applying a predetermined current to the other drive coil and displacing the valve body toward the other end after the valve body has been displaced to near the intermediate position between the first and second drive coils. The engine valve drive is
This is effective for reducing power consumption.

A method for setting an initial position of the valve body in the valve driving device for an internal combustion engine having the above-described structure, wherein the self-inductance of the displacement detection coil is set to a predetermined value when the drive coil is de-energized. The method for setting the initial position of the valve element, which adjusts the relative position between the valve element and the drive coil, is effective for easily adjusting the initial position of the valve element.

[0015]

In the valve drive device for an internal combustion engine according to the present invention,
Since the displacement detection coil is formed by a winding having a smaller diameter than the drive coil, the displacement detection coil is formed while securing a large number of turns in a small space. Therefore, when the valve body is displaced due to a change in the electromagnetic force of the drive coil, thereby changing the magnetic resistance of the magnetic circuit surrounding the displacement detection coil,
The self-inductance of the displacement detection coil changes its value greatly.

The displacement amount detecting means accurately detects the displacement amount of the valve body based on the self-inductance of the displacement detecting coil whose value largely changes in accordance with the displacement of the valve body.

Further, since the displacement detecting coil and the driving coil are provided with a driving coil coaxially and overlapping each other, when the magnetic flux generated by the driving coil changes, the two terminals of the displacement detecting coil are connected to each other. Generates an induced electromotive force.

At this time, since the displacement detection coil has a larger number of windings than the drive coil, the current flowing through the drive coil is controlled by the switch circuit, and the drive coil is generated. When the magnetic flux changes suddenly, a high-voltage induced electromotive force is generated between both terminals of the displacement detection coil, and the capacitor is charged to a high voltage.

Further, the first and second drive coils and the first and second displacement detecting coils are provided at a predetermined distance in the moving direction of the valve body, and the valve body is held by the spring. In a situation where no electromagnetic force is present, the valve body is held between the first and second drive coils.

Therefore, when the drive means stops the current supply from a state in which a current is passed through one of the first and second drive coils and the valve body is displaced, the valve body is turned off. It is displaced toward the intermediate position without giving any electromagnetic force. Therefore, as long as the drive means only starts energizing the other drive coil after the valve element reaches the intermediate position, the valve element is reliably displaced toward the other end.

Therefore, it is not necessary to energize the drive coil until the plunger passes through the intermediate position, and the energy for moving the plunger can be reduced because the plunger is urged by the elastic member.

Incidentally, when assembling the valve drive device for an internal combustion engine having the above structure, it is necessary to accurately set the initial position of the valve body. In this case, the self-inductance of the displacement detection coil is a function of the position of the valve body. Therefore, when the predetermined value set as the self-inductance indicated by the displacement detection coil is realized when the valve body is at the initial position, the valve body is accurately set to the initial position.

[0023]

FIG. 1 shows an overall configuration diagram of a valve drive device for an internal combustion engine according to an embodiment of the present invention. Electromagnetic actuator 1
Numeral 0 denotes an actuator for driving a valve element 14 formed integrally with the valve stem 12 in the vertical direction in the figure.
4 is designed to function as an intake / exhaust valve of an internal combustion engine.

That is, the valve element 14 shown in FIG. 1 can be held at three positions: a valve closing position, a neutral position and a valve opening position with respect to a valve seat 16 provided at an intake / exhaust port of an internal combustion engine. The intake / exhaust port is opened / closed at an arbitrary timing by the electromagnetic actuator 10. In this case, a cam mechanism generally required for the internal combustion engine 4 is not required, so that the mechanical configuration is simplified and sliding loss due to the cam mechanism is eliminated. It is also possible to set the opening / closing valve timing of the intake / exhaust valve to an ideal timing according to the operating condition of the internal combustion engine.

For this reason, according to the valve driving apparatus for an internal combustion engine using the electromagnetic actuator 10, it is possible to remarkably improve the output characteristics of the internal combustion engine as compared with a conventional cam-driven valve driving apparatus.

Hereinafter, the configuration will be described in detail.

The electromagnetic actuator 10 has two cores 20 and 22 made of a magnetic material and separated from each other by a predetermined distance in the direction in which the valve element 14 is displaced. The cores 20 and 22 have donut-shaped grooves for storing the electromagnetic coils 24 and 26, respectively, and are held by the yokes 41 with their openings facing each other.

The electromagnetic coil 24, 26, the displacement detecting coils 32, 34 each formed by winding only winding number N ₁ of small diameter winding on the outer periphery of the bobbin 28, further wound the winding of large diameter on the outer circumference Drive coils 36, 3 wound by a number N ₂
And 8.

The valve stem 1 is provided between the cores 20 and 22.
2 is provided. The plunger 40 is made of a magnetic material, and is urged by springs 42 and 44 inserted into the centers of the cores 20 and 22 to regulate its position.
By applying an external force due to energization to the cores, the state in which the cores 20 and 22 are in close contact with each other can be displaced.

Here, in the present embodiment, the lower end of the spring 44 is regulated by the core 22, while the upper end of the spring 42 is regulated by the lower end of the adjusting screw 46 incorporated in the core 20. Accordingly, the total length of the springs 42 and 44 in the initial state changes together with the degree of tightening of the adjusting screw 46, and accordingly, the relative initial position of the plunger 40 with respect to the cores 20 and 22 also changes.

That is, in the electromagnetic actuator 10, the initial position of the plunger 40 can be adjusted by the tightening degree of the adjusting screw 46. In this embodiment, an intermediate position between the two cores 20 and 22 is set as a relative initial position of the plunger 40 with respect to the cores 20 and 22.

The drive coils 36 and 38 are connected to a drive circuit 48 which allows an appropriate current to flow therethrough at an appropriate timing. 4. The valve drive device for an internal combustion engine according to claim 3, wherein the drive circuit 48 corresponds to the drive means described above, and the drive circuit 48 controls a current flowing through the drive coils 36 and 38 as described below. Is done.

The plunger 40 includes drive coils 36 and 38
Are not generated at all between the cores 20 and 22 as described above. In this case, as shown in FIG. 1, the valve element 14 is also at the neutral position, and the valve element 14 is in a half-open state.

On the other hand, when a predetermined current flows through one of the drive coils, for example, the drive coil 38, and a magnetic flux circulating inside and outside the drive coil 38 is generated due to the current, the plunger 40 is generated by an electromagnetic force generated by the magnetic flux. Is drive coil 3
Attracted to 8. The magnetic flux circulating inside and outside the driving coil 38 circulates in a magnetic circuit including the core 22, the plunger 40, and an air gap formed between the core 22 and the plunger 40, and narrows the air gap to reduce the magnetic resistance. This is because it tries to form a state.

Accordingly, when the electromagnetic force on the plunger 40 exceeds the combined biasing force of the springs 42 and 44, the plunger 40 is displaced toward the core 22 against the combined biasing force, and finally comes into close contact with the core 22. Thereafter, if energization of the drive coil 38 is continued for a desired time, the plunger 40 is in close contact with the core 22 during that time, that is, the valve element 14
Is kept open.

Next, when the energization of the drive coil 38 is stopped, the force holding the plunger 40 in close contact with the core 22 is extinguished, and the springs 42, 44 are again applied to the plunger 40.
Only the combined biasing force is applied. In this case, the plunger 40 starts to be displaced toward the core 20 located above in FIG. 1 without the other drive coil 36 generating any electromagnetic force.

Assuming that no sliding loss occurs in the displacement process, the plunger 40 should make a simple vibration centering on the initial position thereafter, and the core 20 and the plunger 40 are substantially in close contact with each other. Will be displaced.
Therefore, in such a situation, the plunger 40 can be displaced until it comes into close contact with the core 20 only by the electromagnetic coil 24 generating an electromagnetic force capable of compensating for a sliding loss or the like in the displacement process of the plunger 40.

According to the above-described principle, the drive circuit 48 according to the present embodiment stops the flow of a predetermined current to one drive coil 38 (or 36) except when the valve element 14 starts to be driven. Receiving a signal indicating that the plunger 40 has passed the initial position from the quantity detection circuit,
Is configured to start energizing the other drive coil 36 (or 38) after the time when it is estimated that has passed the initial position. Further, the method of detecting the passage of the plunger 40 at the initial position can be obtained by time.

In this case, the energy required for opening and closing the valve element 14 depends on the energy required for keeping the plunger 40 in close contact with the core 20 or 22 and the sliding loss accompanying the operation of the electromagnetic actuator 10. Only the consumed energy is required, and driving can be performed with extremely low power consumption.

The displacement detection coils 32 and 34 are connected to a displacement detection circuit 50 corresponding to the above-described displacement detection means. The displacement detecting circuit 50 detects the displacement amount based on the self-inductance L _32, L ₃₄ change in the displacement detecting coils 32, 34 caused by the displacement of the valve body 14, an internal combustion according to claim 1, wherein thereby the above 2 is a circuit for realizing an engine valve driving device.

FIG. 2 is a circuit diagram of a portion corresponding to the displacement detection coil 32 of the displacement amount detection circuit 50. The circuit shown in the figure is an example of a displacement detecting circuit 50, a Korubittsu oscillator for changing the oscillation frequency F in response to a change in self-inductance L ₃₂ of the displacement detecting coil 32.

[0042] In the present embodiment uses the oscillation frequency F is converted into a voltage by F-V converter 52, the voltage value V as a substitute characteristic value of the self-inductance L ₃₂ of the displacement detecting coil 32 .

That is, the displacement detection circuit 50 shown in FIG.
Where R ₁ = 0, R ₂ = R ₃ = infinity, and resistor 5
Ignoring the contribution of 4, 56, 58, 1 / C = 1 / C ₁ +1
/ When a C ₃ to define a combined capacitance C of the capacitor 60 and 62, the equivalent circuit of Korubittsu type oscillator shown in Fig can be represented as in FIG.

In this case, when the characteristics of the transistor 64 are represented by using the Y parameter shown in the following equation (3), the oscillation frequency F is represented by its determinant ΔY (= Y _i · Y _o -Y _r · Y _f ) and the capacitor Using the capacitance C _{2 of} 64, the self-inductance L ₃₂ of the displacement detection coil 32, and the like, the following expression (4) can be used. However, in the following equation (4), 1 / C ₀ = 1 / C
+ 1 / C ₂ .

[0045]

(Equation 1)

In each of the above equations, the value of the Y parameter is a value uniquely determined by the characteristics of the transistor 64, and C ₀ , C, and C ₂ are also values of the capacitors 60, 62, and 66.
Is a fixed value as the capacitance of the oscillation frequency F
It can be understood as a function of L _32.

On the other hand, as described above, the self-inductance of the electromagnetic coil is a function of the characteristic value K determined by the characteristics of the magnetic circuit surrounding the coil and the number of turns N of the coil (formula (2)). reference). Displacement detection coil 3
Since the number of turns N of 2 is constant, the self-inductance L ₃₂ is a value corresponding to the characteristics of the magnetic circuit surrounding the displacement detection coil 32 and the like.

In the present embodiment, the magnetic resistance of the magnetic circuit formed around the displacement detecting coil 32 changes with the displacement of the valve element 14, and there is no other factor that changes the characteristic value K. showed almost proportional relation with the displacement amount and the self-inductance L ₃₂ of the valve body 14 as shown in FIG. 4, it is possible after all to grasp the oscillation frequency F as a substitute characteristic value of the displacement amount of the valve element 14.

Therefore, if the case where the output voltage V of the FV converter 52 continuously falls below the predetermined voltage is defined as abnormal, for example, if the situation is detected, the electromagnetic actuator may be deemed to be abnormal due to some abnormality. 10 can be recognized as not functioning properly, and appropriate measures such as current cut can be taken.

At this time, the displacement detection coil 32 is
It is configured by winding a number of turns smaller in diameter than the
As a result, the self-inductance
L ₃₂Changes significantly. Therefore, the drive coil 36
Self inductance L₃₆Compared to a configuration that focuses on changes in
The displacement amount of the valve body 14 can be detected with high accuracy.
Also, the displacement detection coil 32 is coaxially
Because it is formed in a compact, another sensor for displacement detection
It can be downsized compared to an additional configuration
It also has an effect.

In this embodiment, the drive coil 36
Although the displacement detection coil 32 is formed inside the drive coil 36, the displacement detection coil 32 may be formed outside the drive coil 36 as long as it is coaxial. The displacement amount detection circuit 50 is not limited to Korubittsu oscillator, as long as it is capable of detecting a substantially self-inductance L _32.

[0052] Furthermore, although only describes a configuration for detecting a displacement amount of the valve body 14 on the basis of convenience self-inductance L ₃₂ change in displacement amount detection coil 32 in the above description, the valve driving apparatus of this embodiment , The displacement detection coil 34 also performs the same function.

Incidentally, when assembling the valve drive device for an internal combustion engine as shown in FIG. 1, it is necessary to accurately adjust the initial position of the plunger 40 to the intermediate position between the cores 20 and 22. In this case, conventionally, for example, a method of adjusting the adjustment screw 46 while measuring the tip position of the valve body 14 has been adopted. However, as in this embodiment, the displacement amount of the valve body 14 is measured by the displacement detection coils 32 and 34. If the change can be detected as a change in the self-inductances L ₃₂ and L ₃₄ , the initial position can be set more easily by using the function.

That is, L ₃₂ and L ₃₄ obtained when the plunger 40 is set to an appropriate position as an initial position are set in advance as reference values, and the adjusting screw 46 is adjusted so that the reference values are realized. If adjusted, an appropriate initial position can be set without using any other measuring instrument.

In the valve driving apparatus for an internal combustion engine according to the present embodiment, the initial position of the plunger 40, that is, the initial position of the valve body 14 is set as described above, thereby realizing the invention according to claim 4. Will be.

FIG. 5 is a circuit diagram of a high-voltage charge / discharge circuit which realizes the above-described second aspect of the present invention by being added to the valve driving device for an internal combustion engine having the above-mentioned structure. This circuit is
Drive coil 36 (38) and displacement detection coil 32 (34)
And a primary side coil and a secondary side coil, respectively, to constitute a transformer and generate a high voltage.

That is, the drive coils 36 (38)
A switch circuit 70 that repeats current flow and cutoff at high speed is connected. A capacitor 74 is connected to the displacement detection coil 32 (34) via a full-wave rectifier circuit 72 including four diodes.

Both terminals of the capacitor 74 are connected to the capacitor 7
The transistor 76 and the load 78 constituting the discharge system 4 are connected in series. The transistor 76 is controlled by the discharge control circuit 80, and is turned on in response to a discharge signal from the discharge control circuit 80.

In the above configuration, when the switch circuit 70 repeatedly turns on and off, the drive coil 36 (3
8), the number of magnetic flux intersecting increases or decreases. Therefore, the direction of the displacement detection coils 32 (34) is alternately reversed, and a high-voltage induced electromotive force is generated. This induced electromotive force is applied to the full-wave rectifier circuit 7.
2 and is applied to both terminals of the capacitor 74 as a DC voltage.

At this time, if the transistor 76 is off, the capacitor 74 is charged by the applied high-voltage induced electromotive force, and the driving coil 36 (38) is connected between the two terminals.
, A voltage higher than the voltage applied to is generated. When the transistor 76 is turned on by the discharge control circuit 80, the charged high voltage can be applied to both ends of the load 78.

As described above, by using the high-voltage charge / discharge circuit of this embodiment, a high voltage can be applied to the load 78 without using an expensive DC-DC converter, and the high voltage can be temporarily applied. It would be extremely beneficial if supply was effective.

The driving coils 36 and 38 of the electromagnetic actuator 10 are one of the effective loads to be supplied with a high voltage temporarily during driving. While the plunger 40 is separated from the cores 20 and 22, a large electromagnetic force is required to displace the plunger 40,
On the other hand, after the plunger 40 comes into close contact with the cores 20 and 22, the contact state can be maintained with a slight electromagnetic force.

For this reason, using the high voltage charging / discharging circuit shown in FIG.
When the contact is made in 2), the switch circuit 70 of the drive coil 36 (or 38) is turned on and off to the extent that the contact state can be maintained, and as a result, the high voltage charged in the capacitor 74 is applied to the plunger 40. When displacing toward the other core 22 (or 20), the other drive coil 38 (or 3
6), the electromagnetic actuator 10
Can be appropriately driven.

As described above, according to the valve driving apparatus for an internal combustion engine of the present embodiment, it is sufficient that the displacement of the valve element 14 can be accurately detected, and that the sliding loss caused by the operation is only compensated for. Power consumption can be generated without using a DC-DC converter, and an excellent effect of reducing power consumption and cost while maintaining a compact size can be obtained.

[0065]

As described above, according to the first aspect of the present invention, by providing the displacement detecting coil which largely changes the self-inductance in accordance with the displacement of the valve body, the displacement amount of the valve body can be accurately measured with a small size. The function of detecting can be realized.

According to the second aspect of the present invention, a transformer can be substantially realized by the drive coil and the displacement detection coil, and a voltage higher than a voltage applied to the drive coil can be applied to the capacitor. it can. Therefore, DC-DC
A highly useful high voltage can be obtained without using an expensive device such as a converter.

Further, according to the third aspect of the present invention, the first
In reciprocating the valve element around the intermediate position of the second drive coil, during the process in which the valve element is displaced from one displacement end toward the other displacement end, only the restoring force of the spring is used up to the intermediate position. It can be displaced reliably. For this reason, the time for flowing the current through the first and second drive coils is short, and power consumption can be reduced.

According to the fourth aspect of the present invention, the initial position of the valve body can be accurately set based on the self-inductance of the displacement detection coil. In this case, since the displacement detection coil has a large number of windings and its self-inductance changes relatively largely with the displacement of the valve body, the initial position can be accurately determined without using any other adjusting device. Can be set.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a valve drive device for an internal combustion engine according to one embodiment of the present invention.

FIG. 2 is a circuit diagram of a displacement amount detection circuit of the valve drive device of the internal combustion engine according to the embodiment.

FIG. 3 is a circuit diagram used for approximation calculation of the oscillation frequency of the displacement detection circuit of the present embodiment.

FIG. 4 is a diagram illustrating a relationship between a displacement amount of a valve body and a self-inductance of a displacement detection coil.

FIG. 5 is a circuit diagram of a high-voltage charge / discharge circuit that generates a high voltage by forming a transformer with a drive coil and a displacement detection coil.

[Explanation of symbols]

 Reference Signs List 10 electromagnetic actuator 14 valve body 20, 22 core 32, 34 displacement detection coil 36, 38 drive coil 40 plunger 42, 44 spring 46 adjustment screw 50 displacement amount detection circuit 70 switch circuit 72 full-wave rectifier circuit 74 capacitor 76 transistor 78 load 80 Discharge control circuit

Claims (4)

(57) [Claims] 1. A valve driving apparatus for an internal combustion engine for driving a valve element of an internal combustion engine by electromagnetic force, comprising: a driving coil for generating an electromagnetic force for driving the valve element; A winding, the displacement detecting coil formed by being wound coaxially with the drive coil a number of times greater than the number of turns of the drive coil, and based on the self-inductance of the displacement detection coil that changes with the displacement of the valve element, A valve driving device for an internal combustion engine, comprising: a displacement amount detecting means for detecting a displacement amount of a valve body. 2. The valve drive device for an internal combustion engine according to claim 1, wherein the capacitor is disposed between both terminals of the displacement detection coil, and charges a charge corresponding to an electromotive force generated in the detection coil. A valve drive device for an internal combustion engine, comprising: a switch circuit that controls energization of a drive coil. 3. A valve driving apparatus for an internal combustion engine for driving a valve element of an internal combustion engine by electromagnetic force, wherein the valve driving apparatus is separated by a predetermined distance in a moving direction of the valve element to generate an electromagnetic force for driving the valve element. And the first and second drive coils, and windings having a smaller diameter than the windings of the first and second drive coils are formed more times than the number of turns of the first and second drive coils, respectively. First and second displacement detection coils wound coaxially with the first and second drive coils, and self-inductances of the first and second displacement detection coils that change with the displacement of the valve element. And a displacement amount detecting means for detecting a displacement amount of the valve body; and in a state where the first and second drive coils do not generate an electromagnetic force, the valve body is connected to the first and second drive coils. An elastic member supported in the middle of the first and second driving coils After applying a predetermined current to any one of the above, the valve body is displaced, and after stopping the current supply, after the valve body is displaced to near the intermediate position of the first and second drive coils, the other drive is performed. A drive means for applying a predetermined current to the coil to apply a displacement toward the other end of the valve body to the valve body. 4. A method for setting an initial position of the valve body in the valve drive device for an internal combustion engine according to claim 1, wherein the drive coil is provided so that a self-inductance of the displacement detection coil has a predetermined value. A method for setting an initial position of the valve element, comprising adjusting a relative position between the valve element and the drive coil when energized.