JPH1193629A - Solenoid valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To exhibit suitable operational characteristics according to the state of an internal combustion engine in opening and closing of a valve element, concerning a solenoid valve suitable as a valve mechanism of the internal combustion engine. SOLUTION: An armature 30 to be displaced together with a valve element 18 is provided. An upper core 32 and a lower core 34 are provided on both sides of the armature 30. An upper coil 40 and a lower coil 42 are respectively housed in the upper core 32 and the lower core 34. An annular projecting part 36 is formed on only the lower core 34 out of the upper core 32 and the lower core 34. The inside diameter a little larger than the outside diameter of the armature 30 is provided on the annular projecting part 36.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electromagnetically driven valve, and more particularly to an electromagnetically driven valve suitable as a valve mechanism for an internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Patent Application Laid-Open No. Hei 4-50204.
As disclosed in No. 8, an electromagnetically driven valve used as a valve mechanism of an internal combustion engine is known. The conventional electromagnetically driven valve has an armature fixed to the valve body. Upper and lower springs are provided above and below the armature. These springs bias the armature toward the neutral position.

An upper core and a lower core are disposed above and below the armature. An upper coil and a lower coil are provided inside the upper core and the lower core, respectively. The upper coil and lower coil are
The supply of the exciting current generates a magnetic flux that flows back and forth between them. When such a magnetic flux is generated, an electromagnetic force (hereinafter, referred to as an attractive force) acts to draw the magnetic flux between the armature and the upper core and between the armature and the lower core. Therefore, according to the above-described conventional electromagnetically driven valve, by supplying a predetermined exciting current to the upper coil or the lower coil, the valve body can be displaced to the valve closing position or the valve opening position.

When the supply of the exciting current to the upper coil or the lower coil is stopped after the valve body is displaced to the valve closing position or the valve opening position, the armature and the valve body generate a single vibration by being urged by a spring. start. If the amplitude of the simple vibration is not attenuated, the armature and the valve body from one displacement end to the other displacement end (hereinafter, referred to as the target displacement end) reach the target displacement end only by the biasing force of the spring. However, displacement of the armature and the valve element involves energy loss due to sliding friction and the like. Therefore, the maximum reaching position of the armature and the valve element due to the urging force of the spring is before the target displacement end.

According to the above-mentioned conventional electromagnetically driven valve, the supply of the exciting current to the upper coil or the lower coil is stopped, and then the supply of the exciting current to the other coil is started at an appropriate timing. The armature and the valve body can be displaced to the target displacement end by supplementing the minute. Thereafter, when an exciting current is alternately supplied to the upper coil and the lower coil at an appropriate timing,
The valve can be opened and closed.

[0006] The above-mentioned conventional electromagnetically driven valve is provided on the outer periphery of the upper core and the outer periphery of the lower core with an annular projection protruding from the end surface of the upper core or the lower core toward the armature side by a predetermined length. The annular protrusion has an inner diameter slightly larger than the outer diameter of the armature. When the above-mentioned annular convex portion is provided, the suction force acting on the armature in a state where the armature is separated from the target displacement end (hereinafter, referred to as a separation-time suction force) is provided with the annular convex portion. It becomes larger than the case without. On the other hand, when the annular convex portion is provided, the suction force acting on the armature when the armature is close to the target displacement end (hereinafter, referred to as a near-time suction force) is provided with the annular convex portion. It is smaller than the case without. Therefore, according to the above-described conventional electromagnetically driven valve, the suction force acting on the armature can be gradually increased while the armature approaches the target displacement end.

When the valve body reaches the valve opening position or the valve closing position, a collision sound is generated due to a collision between the armature and the upper core or the lower core. To suppress the collision sound, it is desirable that the suction force acting on the armature at the time when the armature reaches the target displacement end does not become an unduly large value. In order to reliably displace the armature to the target displacement end, it is necessary to secure a certain amount of suction force at the time of separation. In electromagnetically driven valves, in order to suppress the collision noise while securing a large suction force at the time of separation, it is advantageous that the suction force acting on the armature does not show a sudden increase in the process of the armature approaching the target displacement end. It is. According to the above-mentioned conventional electromagnetically driven valve, the above requirements can be satisfied both when the valve is opened and when the valve is closed. Therefore, according to the above-mentioned conventional electromagnetically driven valve, excellent quietness can be obtained.

[0008]

The load acting on the valve body of the internal combustion engine is not always the same between when the valve is opened and when the valve is closed. For example, the exhaust valve opens when a high combustion pressure remains in the combustion chamber, and closes after the combustion pressure is discharged from the combustion chamber. In this case, a larger load acts on the exhaust valve when the valve is opened than when the valve is closed.

[0009] The attraction force at the time of separation to be ensured for the valve body of the electromagnetically driven valve to reach the target displacement end varies depending on the magnitude of the load acting on the valve body during the displacement process. Specifically, when a large load acts on the valve element in the process of displacing the valve element, it is necessary to ensure a larger suction force at the time of separation than when the load acting on the valve element is small. Therefore, when the electromagnetically driven valve is used as an exhaust valve, when the valve is opened,
A large suction force at the time of separation is required as compared to when the valve is closed.

As described above, the conventional electromagnetically driven valve generates a large suction force at the time of separation when the valve is opened and when the valve is closed, and also generates the suction force when the armature reaches the target displacement end. Increase slowly. According to such characteristics, when the exhaust valve is configured using the electromagnetically driven valve, the valve body can be properly operated both when the valve is opened and when the valve is closed.

However, when the electromagnetically driven valve is used as an exhaust valve, it is not necessary to generate a large suction force when the valve is closed. More specifically, when the electromagnetically driven valve is used as an exhaust valve, the valve body is properly closed regardless of the magnitude of the suction force at the time of separation, if an appropriate suction force at the time of closing is generated when the valve is closed. be able to. In the electromagnetically driven valve, in order to efficiently generate a large suction force at the time of proximity, it is advantageous that the suction force acting on the armature shows a rapid rise in the process of the armature approaching the target displacement end. Therefore, when the electromagnetically driven valve is used as an exhaust valve, in order for the valve element to close properly with low power consumption, the armature acts on the armature in the process of approaching the target displacement end (upper core). It is desirable that the suction force to be applied shows a sharp increase. In this regard, the above-described conventional electromagnetically driven valve, which gradually increases the suction force even when the valve body is closed, still leaves room for improvement in improving power saving characteristics.

The present invention has been made in view of the above points, and has as its object to provide an electromagnetically driven valve that exhibits appropriate operating characteristics according to the state of the internal combustion engine when the valve body is opened and closed. I do.

[0013]

The above object is achieved by the present invention.
As described in the above, the armature displaced together with the valve element, the elastic body placed on both sides of the armature, the first and second cores disposed on both sides of the armature, and the first and second cores respectively. An electromagnetically driven valve including first and second coils housed therein, wherein one of the first and second cores includes a convex portion projecting by a predetermined length toward the other core, and The armature is achieved by an electromagnetically driven valve having a convex part opposing surface opposing a side surface of the convex part when the armature approaches the one core.

[0014] The above object is as described in claim 2.
2. The electromagnetically driven valve according to claim 1, wherein the other of the first and second cores is achieved by an electromagnetically driven valve having a small convex portion smaller than the convex portion. The above object is achieved by an armature displaced together with a valve body, elastic bodies provided on both sides of the armature, and first and second cores provided on both sides of the armature.
An electromagnetically driven valve comprising: first and second coils housed in a first and second core, respectively, wherein the armature protrudes from one side of the first and second cores by a predetermined length. The electromagnetically driven valve is provided with a portion, and the one core is provided with a convex portion opposing surface that opposes a side surface of the convex portion when the armature approaches the one core.

According to a fourth aspect of the present invention, in the electromagnetically driven valve according to the third aspect, the armature is provided on the other side of the first and second cores.
This is achieved by an electromagnetically driven valve having small projections smaller than the projections. In the present invention, when the armature is close to one of the cores, the side surface of the convex portion provided on the one core or the armature faces the convex portion facing surface corresponding to the convex portion. According to this configuration, while the armature approaches one of the cores, a large separation suction force acts on the armature, and the suction force acting on the armature shows a gradual increase tendency. Further, according to the above configuration, in the process of the armature approaching the other core, a relatively small suction force acts on the armature, and the suction force acting on the armature tends to increase rapidly. According to the characteristics of the present invention, when a large load is applied to the valve body when the armature approaches one core, and a large load is not applied to the valve body when the armature approaches the other core, The body can be operated properly with low power consumption.

[0016]

FIG. 1 is a sectional view of an electromagnetically driven valve 10 according to an embodiment of the present invention. The electromagnetically driven valve 10 is used as an exhaust valve of an internal combustion engine. The electromagnetically driven valve 10 is fixed to a cylinder head 12. Cylinder head 1
An exhaust port 14 is formed in 2. A combustion chamber 16 of the internal combustion engine is formed below the cylinder head 12. The electromagnetically driven valve 10 includes a valve element 18 that connects or disconnects the exhaust port 14 and the combustion chamber 16.

The valve body 18 is integrally provided with a valve shaft 20. A valve guide 22 is provided inside the cylinder head 12.
Are arranged. The valve shaft 20 is slidably held by a valve guide 22. At the upper end of the valve shaft 20,
The lower retainer 24 is fixed. Lower retainer 24
A lower spring 26 is provided at the lower part of the lower part. The lower spring 26 urges the lower retainer 24 upward in FIG.

The upper end of the valve shaft 20 is in contact with the armature shaft 28. The armature shaft 28 is a member made of a non-magnetic material. An armature 30 is fixed to the armature shaft 28. The armature 30 is an annular member made of a magnetic material. An upper core 32 and a lower core 34 are provided above and below the armature 30, respectively. The upper core 32 and the lower core 34 are annular members made of a magnetic material. The lower core 34 has an annular convex portion 36. The annular convex portion 36 is
4 is an annular portion protruding by a predetermined length from the surface to the upper core 32 side. The electromagnetically driven valve 10 according to the present embodiment is characterized in that, of the upper core 32 and the lower core 34, only the lower core 34 has the annular convex portion 36.

The annular convex portion 36 has a diameter slightly larger than the outer diameter of the armature 30. Therefore, when the armature 30 approaches the lower core 34 sufficiently, a situation is formed in which the inner wall of the annular convex portion 36 faces the outer peripheral surface of the armature 30. Hereinafter, the outer peripheral surface of the armature 30 (the surface facing the inner peripheral surface of the annular convex portion 36) is referred to as a convex portion facing surface 38.

The upper core 32 and the lower core 34 include
The upper coil 40 and the lower coil 420 are respectively housed. Also, the upper core 32 and the lower core 34
Are provided with bearings 44, 46 at their central portions, respectively. The armature shaft 28 has bearings 44, 46
And are slidably held. A core guide 48 is provided on the outer periphery of the upper core 32 and the lower core 34. The relative position between the upper core 32 and the lower core 34 is maintained in an appropriate relationship by the core guide 48. An upper case 50 and a lower case 52 are fixed to an upper portion of the upper core 32 and a lower portion of the lower core 34, respectively.

At the upper end of the upper case 50, a spring guide 54 and an adjuster bolt 56 are provided. Below the spring guide 54, the applicator 5 is provided.
8 are provided. The upper retainer 58 is connected to the upper end of the armature shaft 28. An upper spring 60 is provided between the spring guide 54 and the retainer 58. Upper spring 60
Urges the retainer 58 and the armature shaft 28 downward in FIG. Armature 30
Is adjusted by the adjuster bolt 56. In this embodiment, the neutral position of the armature 30 is
It is adjusted so that it becomes the center of the upper core 32 and the lower core 34.

The operation of the electromagnetically driven valve 10 will be described below with reference to FIGS. 2 to 9 together with FIG. When the exciting current is not supplied to any of the upper coil 40 and the lower coil 42 in the electromagnetically driven valve 10,
Armature 30 is maintained in its neutral position, that is, in the center of upper core 32 and lower core 34. Armature 3
When the exciting current is supplied to the upper coil 40 in a state where 0 is maintained at the neutral position, an electromagnetic force is generated between the armature 30 and the upper core 32 to draw the armature 30 toward the upper core 32. Therefore, according to the electromagnetically driven valve 10, the armature 30 can be displaced toward the upper core 32 by supplying an appropriate excitation current to the upper coil 40. The valve element 18 is fully closed before the armature 30 contacts the upper core 32. Therefore, according to the electromagnetically driven valve 10, the valve element 18 can be fully closed by supplying an appropriate excitation current to the upper coil 40.

When the supply of the exciting current to the upper coil 40 is stopped while the valve element 18 is maintained in the fully closed state, the valve element 18, the valve shaft 20, the armature shaft 28 and the armature 30 are thereafter By being urged by the upper spring 60 and the lower spring 26, it starts to be displaced downward in FIG. Displacement of the valve element 18 and the like involves energy loss such as sliding friction. According to the electromagnetically driven valve 10, by supplying an exciting current to the lower coil 42, the above-described energy loss is compensated, and the armature 30 is connected to the lower core 34.
The valve body 18 and the like can be displaced until the valve body 18 comes into contact with.
The valve element 18 is fully opened when the armature 30 comes into contact with the lower core 34.

Therefore, according to the electromagnetically driven valve 10, after the supply of the excitation current to the upper coil 40 is stopped, the supply of the excitation current to the lower coil 42 is started at an appropriate timing, whereby the valve element 18 is fully opened. It can be. According to the electromagnetically driven valve 10, the valve element 18 can be properly opened and closed by supplying an appropriate excitation current to the upper coil 40 and the lower coil 42 at an appropriate timing.

As described above, the solenoid-operated valve 10 of the present embodiment
Is characterized in that, of the upper core 32 and the lower core 34, only the lower core 34 has the annular convex portion 36. Hereinafter, the effects of the above features will be described. FIG. 2 shows the flow of the magnetic flux Φ _U flowing back through the upper core 32 and the armature 30 when the predetermined current I ₀ is supplied to the upper coil 40. The flow of the magnetic flux Φ _U shown in FIG. 2 is realized when the armature 30 is largely separated from the upper core 32. Assuming that the number of turns of the upper coil 40 is N, and the magnetic resistance of a magnetic circuit including the upper core 32 and the armature 30 (hereinafter, this magnetic circuit is referred to as an upper magnetic circuit 62) is R _U , a magnetic flux Φ _U flowing back through the upper magnetic circuit 62 Can be expressed as follows:

Φ _U = (N · I ₀ ) / R _U (1) FIG. 3 shows a magnetic flux Φ _L flowing back through the lower core 34 and the armature 30 when a predetermined current I ₀ is supplied to the lower coil 42. The flow of is shown. The flow of the magnetic flux Φ _L shown in FIG. 3 is realized when the armature 30 is largely separated from the lower core 34. The number of turns of the lower coil 42 is N, and the magnetic resistance of a magnetic circuit including the lower core 32 and the armature 30 (hereinafter, this magnetic circuit is referred to as a lower magnetic circuit 64) is R.
If _{L, the} magnetic flux [Phi _L refluxing lower magnetic circuit 64 can be expressed as the following equation.

Φ _L = (N · I ₀ ) / R _L (2) The magnetic resistance R _U of the upper magnetic circuit 62 is
The smaller the air gap formed between the armature 30 and the armature 30, the smaller the value. Similarly, the magnetic resistance _RL of the lower magnetic circuit 64 becomes smaller as the air gap formed between the lower core 34 and the armature 30 becomes smaller.

In this embodiment, the lower core 34 is provided with an annular projection 36 projecting toward the armature 30. When the armature 30 and the lower core 34 are separated from each other, the annular convex portion 36 functions to narrow the air gap between them. Therefore, when the armature 30 is spaced equally from the upper core 32 and the lower core 34, a magnetic resistance R _L of the lower magnetic circuit 64 becomes a value smaller than the magnetic resistance R _U of the upper magnetic circuit 62. Therefore, in this case, the lower magnetic circuit 64, a large magnetic flux [Phi _L relative to the magnetic flux [Phi _U flowing upper magnetic circuit flows.

In the electromagnetically driven valve 10, when the magnetic flux Φ _U flows through the upper magnetic circuit 62 and when the magnetic flux Φ _L flows through the lower magnetic circuit 64, the armature 30 and the upper core 32 or the lower core 34. Between the attraction force in the direction to narrow the air gap of the upper magnetic circuit 62,
Alternatively, an attractive force acts in a direction to narrow the air gap of the lower magnetic circuit 64.

In the situation where the armature 30 is largely separated from the upper core 32 or the lower core 34, the above-mentioned suction force is mainly used to pull the armature 30 toward the upper core 32 or the armature 30 toward the lower core 34. Acts as a force. Further, the above-mentioned suction force becomes larger as the magnetic flux flowing through the air gap to be narrowed is larger.

For this reason, the armature 30 is
2 and equally spaced from the lower core 34, and
Excitation current flowing through upper coil 40 and lower coil 4
When the exciting currents flowing through 2 are equal and I ₀ , a larger attractive force acts between armature 30 and lower core 34 than between armature 30 and upper core 32.
Hereinafter, the armature 30 is referred to as the upper core 32 or the lower core under conditions that are largely separated from the 34 occasion separating the attractive force acting between them attractive force F _F.

FIG. 4 shows that a predetermined current I _{0 is} supplied to the upper coil 40.
5 shows the flow of the magnetic flux Φ _U flowing back through the upper core 32 and the armature 30 when the magnetic flux Φ _U is supplied. The flow of the magnetic flux Φ _U shown in FIG. 4 is realized when the armature 30 is slightly separated from the upper core 32. Upper magnetic circuit 6
Reluctance R _U 2 is a small value As the air gap is small, which is formed between the armature 30 and the upper core 32. Further, as shown in the above equation (1), the magnetic flux Φ _U flowing through the upper magnetic circuit 62 has a larger value as its magnetic resistance _RU is smaller. For this reason, when the armature 30 approaches the upper core 32 as shown in FIG. 4, a large magnetic flux Φ _U is applied to the upper magnetic circuit 62 as compared with the case where the armature 30 is largely separated as shown in FIG. Distribute.

The magnetic flux Φ _U transmitted and received between the armature 30 and the upper core 32 is determined by the armature 30
Even under the condition that the armature 30 is slightly separated from the armature 2, it mainly acts as a force to draw the armature 30 toward the upper core 32 side. For this reason, the force that draws the armature 30 toward the upper core 32 is substantially equal to the magnetic flux Φ _U flowing through the upper magnetic circuit 62 while the armature 30 approaches the upper core 32.
Increase in proportion to Hereinafter, in a situation where the armature 30 and the upper core 32 is close, it referred to as the armature 30 upper core 32 when the proximity of which draws the side attraction force F _N.

FIG. 5 shows a flow of the magnetic flux Φ _L flowing back through the lower core 34 and the armature 30 when the predetermined current I ₀ is supplied to the lower coil 42. Magnetic flux Φ _L shown in FIG.
Is realized when the armature 30 is slightly separated from the lower core 34. The magnetic resistance _RL of the lower magnetic circuit 64 becomes smaller as the air gap formed between the armature 30 and the lower core 34 becomes smaller. As shown in the above equation (2), the lower magnetic circuit 64
Flux [Phi _L flowing becomes larger as the magnetic resistance R _L is small. For this reason, as shown in FIG.
When 0 is closer to the lower core 34, a larger magnetic flux Φ _L flows through the lower magnetic circuit 64 than when both are largely separated as shown in FIG.

A magnetic flux is transmitted and received between the armature 30 and the lower core 34 via an air gap (hereinafter, referred to as an axial air gap) formed between the bottom surface of the armature 30 and the upper surface of the lower core 34. Magnetic flux is also transmitted and received via an air gap (hereinafter, referred to as a radial air gap) formed between the convex portion facing surface 38 of the armature 30 and the annular convex portion 36 of the lower core 34.

The magnetic flux transmitted and received through the axial air gap always acts as a force to draw the armature 30 toward the lower core 34. On the other hand, the magnetic flux transmitted and received via the radial air gap is, as shown in FIG.
Armature 3 to such an extent that the inner wall of
0 and the lower core 34 are close to each other, the armature 30 is not moved to the lower core 34 with respect to the armature 30.
Acts in a direction (radial direction) that does not bias the side. For this reason,
In a situation where the armature 30 and the lower core 34 are close to each other, the force (attraction force F _N at the time of approaching) of pulling the armature 30 to the lower core 34 becomes larger as the magnetic flux flowing through the axial air gap is larger.

The axial air gap decreases in proportion to the amount of displacement of the armature 30 while the armature 30 approaches the lower core 34, and reaches the minimum value “0” when the armature 30 contacts the lower core 34. . On the other hand, when the armature 30 approaches the lower core 34 in the radial direction air gap, the lower end of the convex portion facing surface 38 is
When it reaches the upper end of 6, the minimum value _GMIN is reached. Therefore, after the lower end of the convex portion facing surface 38 reaches the upper end of the annular convex portion 36, the radial air gap is smaller than the axial air gap until the axial air gap becomes _GMIN or less. A state is formed.

The magnetic flux Φ _L flowing through the lower magnetic circuit 64 tends to circulate through a path having a small magnetic resistance. Therefore, while the armature 30 approaches the lower core 34,
In a situation where the radial air gap is larger than the axial air gap, the magnetic flux Φ _L flowing through the lower magnetic circuit 64 is
May flow through a radial air gap. In this case, at the time of closest proximity attraction force F _N is a relatively small value for the magnetic flux [Phi _L. In this case, at the time of closest proximity attraction force F _N exhibits a relatively gradual change in the course of the armature 30 approaches the lower core 34.

Accordingly, in the electromagnetically driven valve 10, the near-attraction force F _N (hereinafter referred to as lower-attraction force) acting between the armature 30 and the lower core 34 is generated between the armature 30 and the upper core 32. Acting proximity suction force F
_This value is smaller than _N (hereinafter, the suction force is applied when approaching the upper side). Further, the change in the suction force at the time of the lower approach when the armature 30 approaches the lower core 34 becomes gentler than the change at the suction force at the time of the upper approach when the armature 30 approaches the upper core 32.

FIG. 6 shows that a predetermined current I _{0 is} supplied to the upper coil 40.
5 shows the flow of the magnetic flux Φ _U flowing back through the upper core 32 and the armature 30 when the magnetic flux Φ _U is supplied. The flow of the magnetic flux Φ _U shown in FIG. 6 is realized when the armature 30 is in contact with the upper core 32. Reluctance R _U of the upper magnetic circuit 62 is the minimum value when the armature 30 and the upper core 32 is in contact. In this case, the maximum magnetic flux Φ _UMIN with respect to the exciting current I ₀ flows through the upper magnetic circuit 62, and a maximum attractive force with respect to the exciting current I ₀ is generated between the armature 30 and the upper core 32. Hereinafter, this suction force is referred to as a contact-time suction force F _C.

FIG. 7 shows the flow of the magnetic flux Φ _L flowing back through the lower core 34 and the armature 30 when the predetermined current I ₀ is supplied to the lower coil 42. Magnetic flux Φ _L shown in FIG.
Is realized when the armature 30 is in contact with the lower core 34. The magnetic resistance R _L of the lower magnetic circuit 64
Is the minimum value when the armature 30 and the lower core 34 are in contact. In this case, the maximum magnetic flux Φ _L flows through the lower magnetic circuit 64 with respect to the exciting current I ₀ . In the present embodiment, an air gap equal to or greater than the minimum value G _MIN is always formed between the convex portion facing surface 38 of the armature 30 and the annular convex portion 36 of the lower core 34. Therefore, armature 3
When 0 and the lower core 34 contact each other, almost all of the magnetic flux Φ _L is transferred between the bottom surface of the armature 30 and the upper surface of the lower core 34. In this case, between the armature 30 and the lower core 34, the excitation current I _0, the armature 3
Attachment suction force F _C that acts between zero and upper core 32
At the time of contact, a suction force F _C approximately equal to the above is applied.

FIG. 8 shows the characteristics of the electromagnetically driven valve 10 with respect to the stroke of the valve element 18. Curve shown in Figure 8, when is displaced between the neutral position and the fully closed position the valve body 18 while supplying an excitation current I ₀ to the upper coil 40, acting between the armature 30 and the upper core 32 Indicates the suction force. Further, the curve shown in FIG. 8 shows the action between the armature 30 and the lower core 34 when the valve element 18 is displaced between the neutral position and the fully open position while supplying the exciting current I ₀ to the lower coil 42. Indicates the suction force to be applied. Further, the straight line shown in FIG. 8 indicates a spring generated by the upper spring 60 and the lower spring 26 when the valve element 18 is displaced between the neutral position and the fully open position or between the neutral position and the fully closed position. Show power.

[0043] As described above, if the upper coil 40 and lower coil 42 excitation current I ₀ equal to and is supplied, apart upon suction force F _F is between between the armature 30 and the lower core 34, the armature and the upper core 32 It is a large value compared to. Further, the suction force F _N when approaching has a smaller value between the armature 30 and the lower core 34 than between the armature and the upper core 32. Further, the contact-time suction force F _C is substantially equal between the armature 30 and the lower core 34 and between the armature 30 and the upper core 32.

Therefore, as shown by the curve, the suction force acting between the armature 30 and the upper core 32 is relatively small when the valve element 18 is located near the neutral position, and the valve element 18 approaches the fully open position. Shows a tendency to increase relatively sharply with. On the other hand, as shown in the curve, the armature 3
0 and the lower core 34 exert a suction force on the valve body 18.
Is relatively large when is located near the neutral position,
8 shows a tendency to increase relatively slowly as it approaches the fully open position.

As described above, the electromagnetically driven valve 10 is used as an exhaust valve of an internal combustion engine. Therefore, the electromagnetically driven valve 10
Attempts to open the valve element 18 in a situation where a high combustion pressure remains in the combustion chamber 16 and closes the valve element 18 after the combustion pressure is discharged. When a high combustion pressure remains in the combustion chamber 16, a large load is applied to the valve body 18 when the valve body 18 is displaced in the valve opening direction. On the other hand, when the valve body 18 is subsequently displaced in the valve closing direction, a very large load is not applied to the valve body 18.

In the electromagnetically driven valve 10, the valve element 18 held at the fully closed position is urged by the upper spring 60 and the lower spring 26 after the supply of the exciting current to the upper coil 40 is stopped. Displaced in the valve opening direction. Similarly, in the electromagnetically driven valve 10, after the supply of the exciting current to the lower coil 42 is stopped, the valve element 18 held at the fully open position is closed by being urged by the upper spring 60 and the lower spring 26. Displaced in the valve direction.

The maximum reaching position at the time of opening of the valve, which is indicated by a mark in FIG. 8, indicates a position that can be reached by the urging of the valve element 18 by the upper spring 60 and the lower spring 26 when the valve is opened. 8 indicates a position reached by the urging of the valve element 18 by the upper spring 60 and the lower spring 26 when the valve is closed. When the valve element 18 is opened, a large load is generated as compared to when the valve element 18 is closed. For this reason, the maximum reaching position at the time of valve opening is a position biased toward the neutral point side as compared with the maximum reaching position at the time of valve closing.

In order to properly displace the valve element 18 to the fully open position, when the valve element 18 is located at the maximum reaching position when the valve is opened, an upper spring 60 and a lower spring are provided between the armature 30 and the lower core 34. It is necessary to generate a suction force that exceeds the spring force generated by the spring 26 (the spring force for urging the valve element 18 to the neutral position). As shown by a curve and a straight line in FIG. 8, the electromagnetic drive valve 10 satisfies the above requirements. Therefore, according to the electromagnetically driven valve 10, the valve element 18 can be appropriately displaced to the fully open position.

When the valve element 18 is stroked toward the upper core 32 by a distance equal to the maximum position when the valve is opened, the suction force acting between the armature 30 and the upper core 32 causes an upper spring This value is smaller than the spring force generated by the lower spring 60 and the lower spring 26. Therefore, the configuration of the lower core 34 is
2, the lower core 34
Does not have the annular convex portion 36, the lower coil 42
By supplying the exciting current I _0, the inability to properly displaced to the fully closed position the valve element 18. In this regard, the electromagnetically driven valve 10 has a characteristic that the valve element 18 can be displaced to the fully closed position with low power consumption.

In order to properly displace the valve element 18 to the fully closed position, the upper spring 60 and the lower spring are provided between the armature 30 and the upper core 32 when the valve element 18 is located at the maximum position when the valve is closed. It is necessary to generate a suction force that exceeds the spring force generated by the spring 26 (the spring force for urging the valve element 18 to the neutral position). As shown by a curve and a straight line in FIG. 8, the electromagnetic drive valve 10 satisfies the above requirements. Therefore, according to the electromagnetically driven valve 10,
The valve element 18 can be appropriately displaced to the fully open position.

Incidentally, the valve element 18 of the electromagnetically driven valve 10 is
Even if the suction force acting between the armature 30 and the upper core 32 is a small value during the period until the valve element 18 reaches the maximum reaching position when the valve element is closed, the valve element 18 has the maximum value when the valve element 18 is closed. As long as the above condition is satisfied at the time of reaching the arrival position, the vehicle is properly displaced to the fully closed position. As shown in FIG. 8, when the exciting current I ₀ is supplied to the upper coil 40, the upper spring 60 and the lower spring 26 are moved between the armature 30 and the upper core 32 when the valve element 18 reaches the maximum reaching position when the valve is closed. A sufficiently large suction force is generated as compared with the generated spring force. Therefore, according to the electromagnetically driven valve 10, the exciting current supplied to the upper coil 40, even smaller value than the predetermined value I _0, it is possible to properly displace the valve element 18 to the fully closed position.

[0052] As shown by the curve and the curve in FIG. 8, in terms of generating a large proximity upon suction force F _N to the excitation current I _0, the structure of the upper core 32 is the lower core 3
4 is more suitable than the structure of FIG. Therefore, when the valve element 18 is located at the maximum reaching position when the valve is closed, the upper spring 6
The structure of the upper core 32 is more suitable than the structure of the lower core 34 for generating a suction force that exceeds the spring force generated by the zero and the lower spring 26 with low power consumption. In the present embodiment, the exciting current supplied to the upper coil 40 is generated by the upper spring 60 and the lower spring 26 between the armature 30 and the upper core 32 when the valve element 18 is located at the maximum reaching position when the valve is closed. It is set to a value that generates a suction force that slightly exceeds the spring force. Therefore, according to the electromagnetically driven valve 10, excellent power saving characteristics can be realized when the valve element 18 is displaced to the fully closed position.

During operation of the internal combustion engine, it is necessary to maintain the valve element 18 in the fully closed position or the fully open position. According to the electromagnetically driven valve 10, after the valve element 18 reaches the fully closed position or the fully opened position, that is, the armature 30 is moved to the lower core 34.
Or, after reaching the upper core 32, the lower coil 42
Alternatively, by supplying an appropriate exciting current to the upper coil 40, the valve element 18 can be maintained at the fully closed position or the fully opened position.

As described above, the armature 30 and the upper core
32, and the armature 30 and the lower core 34
During the excitation current I₀Suction at contact is almost equivalent to
Force F _COccurs. Therefore, according to the electromagnetically driven valve 10,
In addition to maintaining the valve element 18 in the fully closed position,
Excellent power saving characteristics even when maintaining the open position
Can be realized.

As described above, the characteristics of the electromagnetically driven valve 10 of this embodiment are set in consideration of the relationship between the timing at which the valve element 18 opens and closes and the operating state of the internal combustion engine. Therefore, according to the electromagnetically driven valve 10, the valve element 18 can be properly opened and closed while realizing excellent power saving characteristics during operation of the internal combustion engine. In the above-described embodiment, the upper spring 60 and the lower spring 26 are the same as the "elastic body" according to the first aspect, but the upper core 32 and the lower core 34 are used.
In the “first and second cores” of the first aspect, the lower core 34 is in the “one core” of the first aspect, the upper core 32 is in the “other core” of the first aspect,
The annular convex portions 36 respectively correspond to the “convex portions” in the first aspect.

In the above embodiment, the upper core 32 is not provided with a convex portion. However, the present invention is not limited to this.
Alternatively, a convex portion smaller than the annular convex portion 36 may be provided. Next, an electromagnetically driven valve according to a second embodiment of the present invention will be described with reference to FIG. FIG. 9 shows a cross-sectional view of a main part of the electromagnetically driven valve of the present embodiment. In FIG. 9, the same components as those shown in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

The electromagnetically driven valve according to the present embodiment has the lower core 34 and the armature shaft 28 in the configuration shown in FIG.
Is changed to a lower core 70 and an armature shaft 72 shown in FIG. The lower core 70 has an annular projection 74 at a position surrounding the armature shaft 72.
On the other hand, the armature shaft 72 is provided with a concave portion 76 for accommodating the annular convex portion 74 at a connection portion with the armature 30.

As a result of the provision of the concave portion 76 in the armature shaft 72, a convex portion facing surface 78 is formed on the inner peripheral surface of the armature 30. The projection facing surface 78 of the armature 30
When the armature 30 and the lower core 70 are close to each other, the armature 30 faces the inner peripheral surface of the annular convex portion 74. The inner diameter of the armature 30 is set slightly larger than the outer diameter of the annular projection 74. Therefore, a predetermined clearance is always secured between the convex portion facing surface 78 and the annular convex portion 74.

In the electromagnetically driven valve of this embodiment, the annular convex portion 74 and the convex portion facing surface 78 function in the same manner as the annular convex portion 36 and the convex portion facing surface 38 of the first embodiment. Therefore, according to the electromagnetically driven valve of the present embodiment, similarly to the electromagnetically driven valve 10 of the first embodiment, during operation of the internal combustion engine, the valve element 18 is properly opened and closed while achieving excellent power saving characteristics. Can work.

Next, an electromagnetically driven valve according to a third embodiment of the present invention will be described with reference to FIG. FIG. 10 is a sectional view of a main part of the electromagnetically driven valve of the present embodiment. In FIG. 10, the same components as those shown in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

In the electromagnetically driven valve of this embodiment, the lower core 34 and the armature 30 in the configuration shown in FIG.
This is realized by changing to the lower core 80 and the armature shaft 82 shown in FIG. The lower core 80 has a first annular convex portion 84 on the outermost peripheral portion thereof, and has an annular groove 86 on the inner peripheral side of the first annular convex portion 84. A first convex portion facing surface 87 is formed on the inner peripheral surface of the first annular convex portion 84. On the other hand, the armature 82 has a second
An annular projection 88 is provided. On the outer peripheral surface of the second annular convex portion 88, a second convex portion facing surface 90 is formed.

When the armature 82 and the lower core 80 are close to each other, the second annular convex portion 88 is fitted to the annular groove 86 of the lower core 80, and the second convex portion facing surface 90 is provided with the first annular convex portion. The second annular convex portion 88 is provided so as to face the inner wall of the portion 84, that is, the outer peripheral surface of the second annular convex portion 88 faces the first convex portion facing surface 87. The outer diameter of the armature 82 is set slightly smaller than the outer diameter of the first annular projection 84. Therefore, the second annular convex portion 88 and the first convex portion facing surface 8
7, that is, a predetermined clearance is always ensured between the first annular convex portion 84 and the second convex portion facing surface 90.

In the electromagnetically driven valve of the present embodiment, the first annular projection 84 and the second annular projection 88 function in the same manner as the annular projection 36 of the first embodiment. Further, in the electromagnetically driven valve of the present embodiment, the first convex portion facing surface 87 and the second convex portion facing surface 90 function similarly to the convex portion facing surface 38 in the first embodiment. Therefore, according to the electromagnetically driven valve of the present embodiment, similarly to the electromagnetically driven valve 10 of the first embodiment, during operation of the internal combustion engine, the valve element 18 is properly opened and closed while achieving excellent power saving characteristics. Can work.

In the above embodiment, the upper spring 60 and the lower spring 26 correspond to the "elastic body" according to the third aspect, and the upper core 32 and the lower core 80 correspond to each other.
The lower core 80 corresponds to the “one core” according to the third embodiment, and the second annular protrusion 88 corresponds to the “a first protrusion” according to the third embodiment. To the first
The “convex portion facing surface” according to claim 3, wherein the convex portion facing surface 87 is provided.
, Respectively.

In the above embodiment, no projection is provided to protrude from the armature 82 toward the upper core 32. However, the present invention is not limited to this. , Second
A small protrusion may be provided as compared with the annular protrusion 88. In the above embodiment, the first and second annular projections 8 are provided on both the lower core 80 and the armature 82.
4, 88 are provided, but the present invention is not limited to this, and an annular convex portion may be provided only on the armature 82 side.

[0066]

As described above, according to the present invention, a large load is applied to the valve body while the armature approaches one core, and a large load is applied to the valve body while the armature approaches the other core. When the pressure is not applied, the valve element can be appropriately operated with low power consumption.

[Brief description of the drawings]

FIG. 1 is a sectional view of an electromagnetically driven valve according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a state of a magnetic flux Φ _U flowing back and forth between the inner and outer circumferences of an upper coil in a state where an armature and an upper core are separated from each other in the electromagnetically driven valve shown in FIG. 1;

FIG. 3 is a diagram illustrating a state of a magnetic flux Φ _L circulating around the inner and outer peripheries of a lower coil when the armature and the lower core are separated from each other in the electromagnetically driven valve illustrated in FIG. 1;

FIG. 4 is a diagram showing a state of a magnetic flux Φ _U flowing back and forth between the inner and outer circumferences of the upper coil in a situation where the armature and the upper core are close to each other in the electromagnetically driven valve shown in FIG. 1;

FIG. 5 is a diagram illustrating a state of a magnetic flux Φ _L circulating between the inner and outer circumferences of the lower coil in a situation where the armature and the lower core are close to each other in the electromagnetically driven valve illustrated in FIG. 1;

FIG. 6 is a diagram showing a state of a magnetic flux Φ _U flowing back and forth between the inner and outer circumferences of the upper coil in a state where the armature and the upper core are in contact with each other in the electromagnetically driven valve shown in FIG.

7 is a diagram showing a state of a magnetic flux Φ _L flowing back and forth between the inner and outer circumferences of the lower coil in a state where the armature and the lower core are in contact with each other in the electromagnetically driven valve shown in FIG.

FIG. 8 is a diagram showing characteristics of the electromagnetically driven valve shown in FIG.

FIG. 9 is a cross-sectional view illustrating a main part of an electromagnetically driven valve according to a second embodiment of the present invention.

FIG. 10 is a sectional view illustrating a main part of an electromagnetically driven valve according to a third embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 10 electromagnetically driven valve 30; 82 armature 32 upper core 34; 70; 80 lower core 36; 74 annular convex part 38; 78 convex part opposing surface 40 upper coil 42 lower coil 62 upper magnetic circuit 64 lower magnetic circuit 84 first annular convex part 87 first Convex portion facing surface 88 Second annular convex portion 90 Second convex portion facing surface

(72) Inventor Masahiko Asano 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation

Claims (4)

[Claims] An armature displaced together with the valve body; elastic bodies provided on both sides of the armature; first and second cores provided on both sides of the armature;
An electromagnetically driven valve comprising first and second coils respectively housed in a core, wherein one of the first and second cores comprises a projection protruding a predetermined length toward the other core. An electromagnetically driven valve, wherein the armature has a convex portion facing surface that faces a side surface of the convex portion when the armature approaches the one core. 2. The electromagnetically driven valve according to claim 1, wherein the other of the first and second cores has a small convex portion smaller than the convex portion. . 3. An armature displaced with a valve element, elastic bodies disposed on both sides of the armature, first and second cores disposed on both sides of the armature, and first and second cores.
An electromagnetically driven valve comprising first and second coils respectively housed in a core of the armature, wherein the armature has a protrusion protruding by a predetermined length on one side of the first and second cores. An electromagnetically driven valve, wherein the one core includes a convex portion facing surface that faces the side surface of the convex portion when the armature approaches the one core. 4. The electromagnetically driven valve according to claim 3, wherein the armature has a small convex portion smaller than the convex portion on the other side of the first and second cores. Characteristic electromagnetically driven valve.