JP4649800B2 - Solenoid valve - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electromagnetically driven valve, and more particularly to an electromagnetically driven valve suitable as a mechanism for driving an intake valve or an exhaust valve of an internal combustion engine with an electromagnetic force.
[0002]
[Prior art]
Conventionally, for example, JP-A-11-36829 discloses an electromagnetically driven valve that drives an intake valve or an exhaust valve of an internal combustion engine with an electromagnetic force. This electromagnetically driven valve includes an armature made of a magnetic material and two electromagnets arranged above and below the armature. An armature shaft passing through the center of the electromagnet is fixed at the center of the armature.
[0003]
The armature shaft is slidably held in the axial direction by a bush provided in the electromagnet. A valve shaft that communicates with the valve element is connected to the lower end of the armature shaft. Lubricating oil is supplied to the bush from the outside in order to reduce the sliding resistance of the armature shaft.
[0004]
According to the electromagnetically driven valve having the above configuration, by supplying an exciting current to the upper electromagnet, the armature can be attracted to the electromagnet and the valve body can be fully closed. Further, when the exciting current to the upper electromagnet is stopped and the exciting current is supplied to the lower electromagnet, the armature can be attracted to the lower electromagnet and the valve element can be fully opened. Therefore, according to the conventional electromagnetically driven valve, the valve body can be arbitrarily opened and closed by appropriately supplying an exciting current to the two electromagnets.
[0005]
[Problems to be solved by the invention]
In the conventional electromagnetically driven valve, the lubricating oil supplied to the bush reaches the surface of the armature along the armature shaft. The lubricating oil that has reached the surface of the armature becomes an oil film interposed between the two when the armature is adsorbed by the electromagnet, and improves the adhesion between them. As a result, when the oil film is present, the armature is less likely to be separated from the electromagnet after the excitation current is stopped, compared to when the oil film is not present.
[0006]
In an electromagnetically driven valve, in order to accurately open and close the valve body at a desired timing, it is desirable that the delay until the armature is separated from the electromagnet after the supply of the excitation current to the electromagnet is stopped is shorter. In this regard, in the conventional electromagnetically driven valve, the lubricating oil that has reached the surface of the armature has been one factor that deteriorates the opening / closing timing accuracy of the valve body.
[0007]
The present invention has been made in order to solve the above-described problems, and provides an electromagnetically driven valve that can sufficiently suppress the influence of the lubricating oil that has reached the surface of the armature on the accuracy of the opening / closing timing of the valve body. The purpose is to provide.
[0008]
[Means for Solving the Problems]
  The invention according to claim 1 is an electromagnetically driven valve that opens and closes a valve body by electromagnetic force,
  An electromagnet for generating the electromagnetic force;
  An armature disposed opposite to the electromagnet;
  An armature shaft fixed to the armature;
  A wet holding unit that slidably holds the armature shaft using a lubricant so that the armature and the electromagnet are in contact with each other and separated from each other; and
  An oil repellent coating formed on a contact surface between the armature and the electromagnet;
  A valve shaft fixed to the valve body;
  A valve guide for slidably holding the valve shaft,
  The valve shaft includes a carbon relief that makes the valve shaft thinner than the sliding portion between the valve body and the sliding portion that slides with the inner wall of the valve guide,
  The carbon relief is formed so as to be located outside the valve guide when the electromagnetically driven valve is stopped.It is characterized by that.
[0009]
The invention according to claim 2 is the electromagnetically driven valve according to claim 1,
The armature includes a magnetic part made of a magnetic material containing silicon,
The oil-repellent coating includes a fluorocarbon layer and a silane coupling layer that bonds the fluorocarbon layer and the magnetic part.
[0010]
The invention according to claim 3 is the electromagnetically driven valve according to claim 1,
The armature includes a magnetic part made of a magnetic material containing silicon,
The oleaginous film includes a methylhydrogensiloxane layer.
[0011]
The invention according to claim 4 is the electromagnetically driven valve according to any one of claims 1 to 3,
A holding block for holding the electromagnet;
A cushioning material interposed between the electromagnet and the holding block;
Is further provided.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. In addition, the same code | symbol is attached | subjected to the element which is common in each figure, and the overlapping description is abbreviate | omitted.
[0014]
Embodiment 1 FIG.
FIG. 1 is a cross-sectional view for explaining the configuration of an electromagnetically driven valve 10 according to Embodiment 1 of the present invention.
An electromagnetically driven valve 10 shown in FIG. 1 includes a valve body 12 that functions as an exhaust valve of an internal combustion engine. The valve body 12 is disposed in the exhaust port 14 of the internal combustion engine. The exhaust port 14 is provided with a valve seat 16, and the exhaust port 14 is opened and closed when the valve body 12 is seated on the valve seat 16 or separated from the valve seat 16.
[0015]
The valve body 12 is fixed to the tip of the valve shaft 18. The valve shaft 18 is slidably held by a valve guide 20. A lower retainer 22 is fixed to the valve shaft 18 above the valve guide 20. Below the lower retainer 22, a lower spring 24 that generates an elastic force that biases the valve shaft 18 upward is disposed.
[0016]
The upper end of the valve shaft 18 is also connected to an armature shaft 28 via a lash adjuster 26. The lash adjuster 26 is a functional component having a function of expanding and contracting as necessary in order to appropriately change the relative position of the valve shaft 18 and the armature shaft 28. According to the lash adjuster 26, the state in which the valve body 12 can be displaced to the fully closed position is always maintained while the play between the armature shaft 28 and the valve shaft 18 is zero regardless of the thermal expansion of the valve shaft 18 or the like. it can.
[0017]
The armature shaft 28 is provided so as to extend along the central axis of the armature 30. The armature 30 is a disk-shaped member made of a magnetic material. The armature 30 is required to have a property of generating a high magnetic flux density in a low magnetic field region of a static magnetic field and suppressing iron loss (eddy current loss) in an alternating magnetic field sufficiently small. In order to satisfy this requirement, in this embodiment, the armature 30 is formed of an Fe—Si based magnetic material.
[0018]
An applicator 32 is fixed to the upper end of the armature shaft 28. An upper spring 34 that generates an elastic force that biases the armature shaft 28 downward is arranged above the upper retainer 32. The upper end position of the upper spring 34 is regulated by the adjuster 36. In the electromagnetically driven valve 10, the neutral position of the armature shaft 28 is adjusted by an adjuster 36.
[0019]
A lower electromagnet 42 including a lower core 38 and a lower coil 40 is disposed below the armature 30. An upper electromagnet 48 including an upper core 44 and an upper coil 46 is disposed above the armature 30. Wet bushes 50 and 52 for slidably holding the armature shaft 28 are disposed in the central portion of the lower core 38 and the central portion of the upper core 44, respectively. Lubricating oil is supplied to the bushes 50 and 52 through an oil passage (not shown).
[0020]
A cap member 54 that holds the adjuster 36 is disposed above the upper core 44. The lower core 38, the upper core 44, and the cap member 54 are fixed to a holding block 56, respectively. A buffer material 58 is sandwiched between the holding block 56 and the lower core 38 and between the holding block 56 and the upper core 44. According to the cushioning material 58, the vibration accompanying the operation of the armature 30 can be attenuated sufficiently small before being transmitted to the holding block 52.
[0021]
The position of the armature shaft 28 is such that the armature 30 is positioned approximately at the center between the lower core 38 and the upper core 44 when the electromagnetically driven valve 10 is stopped, that is, when no excitation current is supplied to either the lower coil 40 or the upper coil 46. Has been adjusted. In addition, each part of the electromagnetically driven valve 10 is adjusted so that the valve body 12 is positioned at approximately the center between the fully open position and the fully closed position. Hereinafter, these positions are referred to as “neutral positions” of the armature 30 or the valve body 12.
[0022]
FIG. 1 shows a state in which the armature 30 is in close contact with the upper electromagnet 48 and the valve body 12 is fully closed by supplying an excitation current to the upper coil 46. At this time, the valve body 12 is seated on the valve seat 16, that is, is fully closed.
[0023]
When the energization of the upper coil 46 is stopped from the state shown in FIG. 1, the armature 30 is biased by the lower spring 24 and the upper spring 34 and is displaced beyond the neutral position to the vicinity of the lower electromagnet 42. When an exciting current is supplied to the lower coil 40 at a timing when the armature 30 approaches the lower electromagnet 42, the armature 30 can be drawn to the lower electromagnet 42 to displace the valve body 12 to the fully open position. Thereafter, the opening / closing operation of the valve body 12 can be continued by alternately interrupting and supplying the excitation current on the lower coil 40 side and the upper coil 46 side.
[0024]
As described above, the electromagnetically driven valve 10 includes the lower spring 24 and the upper spring 34. These springs 24, 34 expand and contract with the opening / closing operation of the valve body 12, and transmit a rotational force in a certain direction to the armature shaft 28 along with the expansion / contraction. As a result, the armature shaft 28 and the armature 30 continue to rotate in a certain direction while the opening / closing operation of the valve body 12 is repeated.
[0025]
During the operation of the electromagnetically driven valve 10, the collision between the armature 30 and the lower core 38 or the upper core 44 is repeated with the opening / closing operation of the valve body 12. At this time, vibration due to the collision of the armature 30 is transmitted to the lower core 38 or the upper core 44. When this vibration is transmitted from the lower core 38 or the upper core 44 to the holding block 56, it spreads throughout the internal combustion engine and generates a large noise. In the present embodiment, the vibration transmitted to the lower core 38 and the upper core 44 is sufficiently damped by the buffer material 58. For this reason, a large vibration is not transmitted to the holding block 56, and excellent quietness is realized in the internal combustion engine.
[0026]
Next, a second feature of the electromagnetically driven valve 10 of the present embodiment will be described with reference to FIG.
FIG. 2 shows an enlarged view of the periphery of the valve shaft 18 provided in the electromagnetically driven valve 10. More specifically, FIG. 2 shows a state in which the electromagnetically driven valve 10 is stopped, that is, a state in which the armature 30 and the valve body 12 are in their neutral positions.
[0027]
As shown in FIG. 2, a carbon relief 60 is provided on the valve shaft 18 between a portion that is slidably held by the valve guide 20 and the valve body 12. The valve shaft 18 has a diameter D substantially equal to the inner diameter of the valve guide 20 at a portion held by the valve guide 20. In the carbon relief 60, the diameter of the valve shaft 18 is set to D−ΔD smaller than the diameter D by a predetermined amount ΔD. In the present embodiment, the carbon relief 60 is formed such that the upper end position thereof is located below the lower end position of the valve guide 20 while the electromagnetically driven valve 10 is stopped. FIG. 2 shows a state in which a distance of a predetermined length h is secured between the upper end of the carbon relief 60 and the lower end of the valve guide 20.
[0028]
Immediately after the internal combustion engine is stopped (immediately after the electromagnetically driven valve 10 is stopped), the oil adhering to the inside of the exhaust port 14 flows down from the upper side to the lower side. At that time, the inside of the exhaust port 14 is so hot that the oil that has flowed down in this way is burnt. For this reason, carbon tends to adhere to the valve shaft 18 below the valve guide 20 while the internal combustion engine is stopped.
[0029]
When the upper end position of the carbon relief 60 is higher than the lower end position of the valve guide 20 when the electromagnetically driven valve 10 is stopped, that is, the upper end of the carbon relief 60 is in the valve guide 20 when the electromagnetically driven valve 10 is stopped. If the valve guide 20 is mixed, a gap corresponding to the difference “ΔD” between the inner diameter D of the valve guide 20 and the inner diameter D−ΔD of the valve shaft 18 is formed at the lower end of the valve guide 20.
[0030]
When carbon adheres to the valve shaft 18 in a state where such a gap is generated, a state in which a part of the carbon enters the valve guide 20 from the gap is formed. When the electromagnetically driven valve 10 is started after such a state is formed, carbon is caught between the valve guide 20 and the valve shaft 18 when the valve body 12 moves in the fully closed direction. Resulting in a temporary significant increase in sliding resistance.
[0031]
In the electromagnetically driven valve 10, when the sliding resistance of the valve shaft 18 increases, the operation of the valve body 12 is stopped or the operation is delayed. For this reason, in order to make the electromagnetically driven valve 10 operate smoothly, it is important to surely prevent carbon from being bitten which increases the sliding resistance of the valve shaft 18.
[0032]
In the present embodiment, the valve shaft 18 is configured so that the upper end of the carbon relief 60 is lower than the lower end of the valve guide 20 by a predetermined length h when the electromagnetically driven valve 10 where carbon sludge is deposited stops. According to this configuration, carbon adhering to the valve shaft 18 can be reliably prevented from entering the inside of the valve guide 20. The carbon formed without entering the inside of the valve guide 20 is scraped off by the valve guide 20 as the valve shaft 18 slides. At this time, a large sliding resistance is not generated in the valve shaft 18. Therefore, according to the electromagnetically driven valve 10 of the present embodiment, it is possible to always achieve a good starting characteristic without being affected by the adhesion of carbon to the valve shaft 18.
[0033]
Next, a third feature of the electromagnetically driven valve 10 will be described with reference to FIGS. 3 and 4 together with FIG.
As shown in FIG. 1, the electromagnetically driven valve 10 of this embodiment includes wet bushes 50 and 52 that hold the armature shaft 28. The lubricating oil supplied to these bushes 50 and 52 reaches the surface of the armature 30 along the armature shaft 28. If this lubricating oil remains on the surface of the armature 30 as it is, when the armature 30 comes into close contact with the lower electromagnet 42 or the upper electromagnet 48, an oil film is generated between them.
[0034]
Such an oil film generates a force in a direction that prevents the armature 30 that is in close contact with the lower electromagnet 42 or the upper electromagnet 48 from being separated from the armature 30. It is desirable that such a force is not generated for smoothly operating the electromagnetically driven valve 10. Therefore, in the present embodiment, in order to avoid the formation of the oil film as much as possible, the armature 30 is configured as described below.
[0035]
FIG. 3A is a perspective view of the armature 30 and the armature shaft 28. FIG. 3B is a cross-sectional view obtained by cutting the armature 30 along the BB line shown in FIG.
[0036]
As shown in FIG. 3A, the armature 30 includes a plurality of oil drain grooves 62 formed in a radial pattern. In the present embodiment, the oil drain groove 62 is provided on the upper surface side of the armature 30 in which lubricating oil tends to accumulate. According to the oil drain groove 62, it is possible to capture the lubricating oil that has reached the surface of the armature 30 and reduce the amount of lubricating oil that forms the base of the oil film.
[0037]
As shown in FIG. 3B, the armature 30 includes a magnetic part 64 made of a Fe—Si based magnetic material and an oil-repellent coating 66 that covers the surface of the magnetic part 64. The oil repellent coating 66 is formed so as to cover the interior of the oil drain groove 62 together with the surface of the armature 30.
[0038]
FIG. 4 is a diagram showing the structure of the armature 30 at the molecular structure level. Silicon oxide generated by natural oxidation is present on the surface of the magnetic part 64. The oil-repellent coating 66 includes a silane coupling layer 68 bonded to the silicon oxide and a fluorocarbon layer 70 formed thereon.
[0039]
The silane coupling layer 68 and the fluorocarbon layer 70 can each be formed by a known method and at a film formation temperature of 200 ° C. or less. The silane coupling layer 68 has a characteristic of firmly bonding an inorganic material (magnetic part 64) containing silicon and an organic layer such as the fluorocarbon layer 70. The fluorocarbon layer 70 has excellent oil repellency. Therefore, according to the structure shown in FIG. 4, it is possible to realize the oil-repellent film 66 that covers the surface of the magnetic part 64 with a strong binding force and exhibits excellent oil repellency.
[0040]
When the surface of the armature 30 is covered with the oil repellent film 66, the lubricating oil that has flowed down onto the armature 30 becomes spherical and moves on the surface. As a result, the lubricating oil is easily captured in the oil drain groove 62 or falls off the surface of the armature 30. In particular, in the electromagnetically driven valve 10 of the present embodiment, the armature 30 rotates with the opening / closing operation of the valve body 12 as described above. For this reason, the lubricating oil that has flowed down on the surface of the armature 30 is quickly removed from the surface by centrifugal force.
[0041]
When the lubricating oil that has reached the surface of the armature 30 is quickly removed from the surface as described above, even if the armature 30 contacts the upper electromagnet 48, an oil film that prevents the separation between the two is not formed. . For this reason, according to the electromagnetically driven valve 10 of the present embodiment, it is possible to realize excellent control accuracy with respect to the opening / closing timing of the valve body 12 while using the wet bushes 50 and 52.
[0042]
The silane coupling layer 68 and the fluorocarbon layer 70 used as components of the oil-repellent film 66 in the present embodiment each show good wettability with respect to the material used as the base in the present embodiment, and are extremely thin. It has a characteristic that the base can be sufficiently covered with a film thickness. For this reason, according to the structure of the present embodiment, the oil-repellent film 66 that stably exhibits high oil repellency on the entire surface can be formed with an extremely thin film thickness of about 20 to 50 angstroms.
[0043]
The oil repellent coating 66 repeatedly collides with the upper electromagnet 48 as the armature 30 operates. Accordingly, the oil repellent coating 66 is required to have high durability. As the oil repellent film 66 is thicker, cracks are more likely to occur due to the influence of deflection caused by the collision with the upper electromagnet 48. In order to prevent the occurrence of this crack, it is desirable that the film thickness of the oil repellent film 66 is 5000 angstroms or less. In the present embodiment, the film thickness of the oil-repellent film 66 can be set to 20 to 50 angstroms that is sufficiently thinner than the desired film thickness. For this reason, according to the structure of the present embodiment, high durability can be imparted to the oil-repellent coating 66.
[0044]
In the electromagnetically driven valve 10, the electromagnetic force acting between the armature 30 and the upper electromagnet 48 becomes larger as the air gap between them becomes smaller. More precisely, the electromagnetic force becomes larger as the distance between the magnetic part 64 of the armature 30 and the upper core 44 is shorter. That is, in the configuration of the present embodiment, the oil-repellent film 66 is an air gap as a component of the magnetic circuit, and it is desirable that the film thickness is as thin as possible in order to efficiently generate a large electromagnetic force.
[0045]
As described above, in this embodiment, the film thickness of the oil-repellent film 66 is set to a sufficiently thin 20 to 50 angstrom. For this reason, according to the structure of the present embodiment, the armature 30 is efficiently large when it is in contact with the upper electromagnet 48 even though the magnetic portion 64 of the armature 30 is covered with the oil repellent coating 66. Magnetic flux density can be generated.
[0046]
When the armature 30 is heat-treated at a high temperature, the magnetic characteristics of the magnetic part 64 of the armature 30 may deteriorate due to the influence of thermal distortion. In this embodiment, the temperature of the heat treatment for forming the oil-repellent film 66 is set to 200 ° C. or lower as described above, that is, a temperature that does not deteriorate the magnetic characteristics of the magnetic part 64. For this reason, the structure of the armature 30 shown in FIG. 4 can be realized without deteriorating the magnetic characteristics of the magnetic part 64.
[0047]
Incidentally, in the first embodiment described above, the oil drain groove 62 and the oil repellent coating 66 are formed only on the upper surface of the armature 30, but the present invention is not limited to this. That is, the oil drain groove 62 and the oil repellent film 66 may be formed on both the upper surface and the lower surface of the armature 30.
[0048]
In the first embodiment described above, the oil drain groove 62 and the oil repellent film 66 are provided on the surface of the armature 30, but the present invention is not limited to this. That is, the oil drain groove 62 and the oil repellent film 66 may be provided on the electromagnets 42 and 48 side in place of the surface of the armature 30 or together with the surface of the armature 30.
[0049]
Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to FIG. The electromagnetically driven valve of the present embodiment has the same configuration as that of the electromagnetically driven valve 10 of the first embodiment except for the structure of the oil-repellent film that covers the surface of the armature. Hereinafter, for the sake of convenience, the configuration of the electromagnetically driven valve of the present embodiment will be described using the same reference numerals as those of the first embodiment.
[0050]
FIG. 5 shows a diagram representing the structure of the armature 30 used in the electromagnetically driven valve of the present embodiment at the molecular structure level. As shown in FIG. 5, in this embodiment, the oil-repellent film 66 that covers the magnetic part 64 of the armature 30 is composed of a methylhydrogensiloxane layer.
[0051]
Methylhydrogensiloxane is firmly bonded to silicon oxide existing on the surface of the magnetic part 64 by a siloxane bond, and exhibits excellent oil repellency like fluorocarbon. Further, the oil-repellent film 66 in this embodiment can be formed at a temperature of 200 ° C. or lower, and is sufficiently stable with a film thickness sufficiently thinner than 5000 angstroms, similar to that in the first embodiment. Oiliness can be realized. For this reason, according to the electromagnetically driven valve of the present embodiment, the same effect as that of the electromagnetically driven valve 10 of the first embodiment can be obtained.
[0052]
Embodiment 3 FIG.
Next, a third embodiment of the present invention will be described with reference to FIG.
In the first or second embodiment described above, the object to which the present invention is applied is limited to the electromagnetically driven valve 10 having a cylindrical bulk structure core (lower core 38 and upper core 44). However, the electromagnetically driven valve to which the present invention can be applied is not limited to this type. That is, the present invention can also be applied to an electromagnetically driven valve having a rectangular laminated core.
[0053]
FIG. 6A is a view for explaining the structure of an electromagnetically driven valve 80 according to Embodiment 3 of the present invention. FIG. 6B is a view showing a cross section of the main part of the electromagnetically driven valve 80 as viewed in the direction of arrow B shown in FIG.
[0054]
The electromagnetically driven valve 80 shown in FIGS. 6A and 6B includes a lower core 82 and an upper core 84 having a rectangular laminated structure. Each of the lower core 82 and the upper core 84 is formed by laminating a plurality of magnetic plates such as silicon steel plates while being insulated from each other. The magnetic plates are stacked in close contact with each other in the direction perpendicular to the paper surface in FIG. 6A, that is, in the left-right direction in FIG.
[0055]
As in the case of the lower core 38 and the upper core 44 in the first embodiment, a lower coil or an upper coil (not shown) is built in the lower core 82 and the upper core 84, respectively. According to the core of the rectangular laminated structure, when the magnetic flux density generated by these coils changes, the eddy current loss caused by the change can be reduced. Therefore, according to the electromagnetically driven valve 80 of the present embodiment, higher energy efficiency can be realized as compared with the electromagnetically driven valve 10 of the first embodiment.
[0056]
The electromagnetically driven valve 80 according to this embodiment includes a bottom plate 86 below the lower core 82 and a lower side wall 88 around the lower core 82. A cap member 90 is provided above the upper core 84, and an upper side wall 92 is provided around the upper core 84. A cushioning material 94 is provided below the bottom plate 86, between the bottom plate 86 and the lower core 82, between the lower side wall 88 and the upper side wall 92, or between the upper core 84 and the cap member 90.
[0057]
According to the cushioning material 94, the vibration transmitted to the lower core 82 or the upper core 84 in accordance with the operation of the armature 30 can be sufficiently damped similarly to the cushioning material 58 in the first embodiment. For this reason, the electromagnetically driven valve 80 of the present embodiment can also achieve quietness equivalent to that of the electromagnetically driven valve 10 of the first embodiment.
[0058]
Further, the electromagnetically driven valve 80 of the present embodiment has a carbon relief 60 that satisfies the same conditions as in the case of the first embodiment. For this reason, according to the electromagnetically driven valve 80 of the present embodiment, as in the case of the first embodiment, it is possible to prevent carbon from getting into the valve guide 20 and realize excellent startability.
[0059]
Further, the electromagnetically driven valve 80 of the present embodiment includes the armature 30 having the oil drain groove 62 and the oil repellent coating 66 as in the case of the first or second embodiment. Unlike the case of the first or second embodiment, this armature 30 is a rectangle having the side shown in FIG. 6A as the long side and the side shown in FIG. 6B as the short side. And it is comprised so that it may not rotate.
[0060]
For this reason, in this embodiment, centrifugal force does not act on the lubricating oil that has reached the surface of the armature 30. However, the lubricating oil becomes spherical on the oil-repellent coating 66, and most of the lubricating oil falls off from the surface of the armature 30 as the armature 30 moves up and down. For this reason, even with the electromagnetically driven valve 80 of the present embodiment, it is possible to achieve excellent accuracy with respect to the opening / closing timing of the valve body 12 as in the case of the first or second embodiment.
[0061]
By the way, although Embodiment 1 thru | or 3 mentioned above is limited when the valve body 12 of the electromagnetically driven valves 10 and 80 is an exhaust valve, this invention is not limited to this. That is, the electromagnetically driven valves 10 and 80 may be used as an intake valve and a drive mechanism thereof.
[0062]
【The invention's effect】
  Since the present invention is configured as described above, the following effects can be obtained.
  According to the first aspect of the present invention, since the contact surface between the armature and the electromagnet is covered with the oil-repellent coating, most of the lubricating oil that has reached the contact surface from the wet holding part flows down as oil droplets. Therefore, according to the present invention, it is possible to effectively prevent an oil film from being formed on the contact surface between the armature and the electromagnet from being separated from each other, and to realize excellent control accuracy with respect to the opening / closing timing of the valve body. it can.According to the present invention, the carbon relief is located outside the valve guide when the electromagnetically driven valve is stopped. For this reason, according to the present invention, it is possible to realize an electromagnetically driven valve with good startability by avoiding the accumulation and adhesion of carbon in the valve guide while the electromagnetically driven valve is stopped.
[0063]
According to invention of Claim 2, the surface of an armature can be covered with the fluorocarbon layer excellent in oil repellency. Moreover, this invention can improve the intensity | strength and adhesiveness of a fluorocarbon layer by interposing a silane coupling layer. Therefore, according to the present invention, the surface of the armature can be covered with an oil-repellent film that is excellent in oil repellency and excellent in reliability and durability.
[0064]
According to the invention described in claim 3, the surface of the armature can be covered with the methylhydrogensiloxane layer. The methyl hydrogen siloxane layer is excellent in oil repellency and is a layer that exhibits high strength on an inorganic material containing silicon. Therefore, according to the present invention, the surface of the armature can be covered with an oil-repellent film that is excellent in oil repellency and excellent in reliability and durability.
[0065]
According to the fourth aspect of the present invention, since the cushioning material is disposed between the electromagnet and the holding block, an electromagnetically driven valve having excellent silence can be realized.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining a configuration of an electromagnetically driven valve according to Embodiment 1 or 2 of the present invention.
FIG. 2 is an enlarged view of the periphery of a valve shaft included in the electromagnetically driven valve shown in FIG.
FIG. 3 is a view for explaining the structure of an armature provided in the electromagnetically driven valve shown in FIG. 1;
FIG. 4 is a diagram showing the structure of an armature included in the electromagnetically driven valve according to the first embodiment of the present invention at a molecular level.
FIG. 5 is a view showing the structure of an armature provided in an electromagnetically driven valve according to Embodiment 2 of the present invention at a molecular level.
FIG. 6 is a view for explaining the structure of an electromagnetically driven valve according to a third embodiment of the present invention.
[Explanation of symbols]
10; 80 Electromagnetically driven valve
12 Disc
18 Valve stem
20 Valve guide
28 Armature axis
30 Armature
38 lower core
40 Lower coil
42 Lower electromagnet
44 Upper Core
46 Upper coil
48 Upper electromagnet
50,52 Wet bush
58; 94 cushioning material
60 carbon relief
62 Oil drain groove
64 Magnetic part
66 Oil repellent coating
68 Silane coupling layer
70 Fluorocarbon layer

Claims (4)

An electromagnetically driven valve that opens and closes the valve body by electromagnetic force,
An electromagnet for generating the electromagnetic force;
An armature disposed opposite to the electromagnet;
An armature shaft fixed to the armature;
A wet holding unit that slidably holds the armature shaft using a lubricant so that the armature and the electromagnet are in contact with each other and separated from each other; and
An oil repellent coating formed on a contact surface between the armature and the electromagnet;
A valve shaft fixed to the valve body;
A valve guide for slidably holding the valve shaft,
The valve shaft includes a carbon relief that makes the valve shaft thinner than the sliding portion between the valve body and the sliding portion that slides with the inner wall of the valve guide,
The carbon relief is formed so as to be positioned outside the valve guide when the electromagnetic relief valve is stopped . The armature includes a magnetic part made of a magnetic material containing silicon,
The electromagnetically driven valve according to claim 1, wherein the oil-repellent coating includes a fluorocarbon layer and a silane coupling layer that bonds the fluorocarbon layer and the magnetic part. The armature includes a magnetic part made of a magnetic material containing silicon,
The electromagnetically driven valve according to claim 1, wherein the oleaginous coating includes a methylhydrogensiloxane layer. A holding block for holding the electromagnet;
A cushioning material interposed between the electromagnet and the holding block;
The electromagnetically driven valve according to any one of claims 1 to 3, further comprising:

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