JP6224527B2 - Insulating substrate for laser plug and laser plug - Google Patents

Description

  The present invention relates to a laser plug insulating substrate and a laser plug on which an optical element such as YAG is held.

  2. Description of the Related Art Conventionally, a laser plug base and a laser plug having a cylindrical base for housing an optical element, a lens, and an optical fiber are known for igniting an air-fuel mixture of an internal combustion engine such as an automobile engine. (For example, see Patent Document 1).

JP 2010-021284

  In the laser plug in which the optical element is housed in the cylindrical space of the base, if the position of the optical element is shifted due to vibration or the like, the position of the pulse light emitted from the optical element is shifted. It may be difficult to ignite the engine air-fuel mixture well. Therefore, the width dimension of the cylindrical space of the base and the width dimension of the optical element are made the same so that the optical element is not misaligned within the base.

  However, when a laser plug is used, the optical element and the base are expanded by heat generated from the optical element and the like, and stress due to a difference in thermal expansion between the optical element and the base is applied to the optical element, and the characteristics of the optical element are degraded. There was a possibility. As a result, it may be difficult to ignite an air-fuel mixture of an internal combustion engine such as an automobile engine.

  According to one aspect of the present invention, the insulating base for a laser plug is a cylindrical insulating base having a space for holding an optical element, a lens, and an optical fiber therein, and the inner wall of the insulating base has a groove. Have.

  According to another aspect of the present invention, a laser plug includes the laser plug insulating base configured as described above, and the optical element, the lens, and the optical fiber housed in the laser plug insulating base.

  An insulating base for a laser plug according to one aspect of the present invention is a cylindrical insulating base having a space for holding an optical element, a lens, and an optical fiber therein, and an inner wall of the insulating base has a groove. Therefore, the groove on the inner wall of the insulating base that is in contact with the optical element can alleviate the stress applied to the optical element due to the difference in thermal expansion between the optical element and the insulating base, and the optical element has good characteristics. Can be made. As a result, the air-fuel mixture of an internal combustion engine such as an automobile engine can be ignited satisfactorily.

  A laser plug according to another aspect of the present invention includes an insulating base for a laser plug having the above-described configuration, an optical element, a lens, and an optical fiber held by the insulating base for a laser plug. It can be good with respect to ignition of the engine mixture.

It is sectional drawing which shows the laser plug in embodiment of this invention. It is the principal part expanded sectional perspective view which expanded the insulating base for laser plugs in the A section of FIG. It is a principal part expanded sectional perspective view which shows the other example of the laser plug in embodiment of this invention. It is a principal part expansion perspective view which shows the other example of the laser plug in embodiment of this invention. It is a principal part expanded sectional perspective view which shows the other example of the laser plug in embodiment of this invention. It is a principal part expanded sectional perspective view which shows the other example of the laser plug in embodiment of this invention.

  Exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

  As shown in FIGS. 1 to 5, the laser plug in the first embodiment of the present invention includes a laser plug insulating substrate 1, an optical element 2 and a lens 3 held on the laser plug insulating substrate 1. And an optical fiber 4. The laser plug is mounted on an internal combustion engine such as an automobile engine.

  The laser plug insulating substrate 1 has a cylindrical shape with a space inside. The laser plug insulating substrate 1 functions as a holder for holding the optical element 2, the lens 3, and the optical fiber 4 therein, and the optical element 2, the lens 3, and the optical fiber 4 are disposed in the space of the laser plug insulating substrate 1. Stored and retained.

  For the laser plug insulating base 1, for example, a ferrule that is a ceramic such as an aluminum oxide sintered body (alumina ceramics), an aluminum nitride sintered body, or nitride can be used.

  If the insulating base for laser plug 1 (ferrule) is made of, for example, an aluminum oxide sintered body, after mixing and pulverizing raw material powders such as aluminum oxide, silicon oxide, magnesium oxide and calcium oxide, these A molding material is prepared by adding and mixing an organic binder to the mixed powder, and the molding material is filled into a mold having a structure for molding a space (through hole). In addition, as a structure for forming space, the convex part corresponding to space is mentioned, for example. That is, a mold having a convex portion corresponding to the space is used. A molded body is obtained by performing press molding, injection molding, cast molding, and extrusion molding on the filled molding material at a predetermined pressure, and the obtained molded body is fired at a high temperature (about 1600 ° C). It is produced by.

The insulating base 1 for laser plugs has a through hole width of about 0.5 to 2 mm, and the optical element 2, the lens 3 and the optical fiber 4 can be pushed into the through holes of the insulating base 1 for laser plugs and held well. It has become a thing.

The inner wall of the laser plug insulating substrate 1 has a groove 1a (also referred to as a first groove 1a). With this configuration, even if the optical element 2 and the insulating base for laser plug 1 are expanded by heat generated from the optical element 2 or the like using the laser plug, the insulating base for laser plug 1 is expanded. The groove 1a on the inner wall of the optical element 2 can alleviate the stress applied to the optical element 2 due to the difference in thermal expansion between the optical element 2 and the insulating base 1 for laser plug, and the characteristics of the optical element 2 are improved. It becomes possible.

  The groove 1a on the inner wall of the laser plug insulating substrate 1 is formed by using, for example, a mold provided with streak-like unevenness at a position located on the inner wall of the laser plug insulating substrate 1, or the through hole of the sintered body. It can be produced by polishing the inner peripheral surface.

  2, when the groove 1a on the inner wall of the laser plug insulating substrate 1 extends in the longitudinal direction of the inner wall of the laser plug insulating substrate 1, the optical element 2 is connected to the laser plug insulating substrate. When disposed in the space 1, the optical element 2 can be easily pushed in, which is preferable.

  Further, as in the example shown in FIG. 3, if the groove 1a on the inner wall of the laser plug insulating substrate 1 is inclined with respect to the longitudinal direction of the inner wall of the laser plug insulating substrate 1, vibration or the like may occur. The optical element 2 can be prevented from being displaced in the longitudinal direction of the inner wall of the insulating base 1 for laser plugs. As a result, the air-fuel mixture of the internal combustion engine can be favorably ignited, which is preferable. It will be a thing. In this case, the groove 1a may be formed in a spiral shape on the inner wall of the laser plug insulating substrate 1.

  When the angle θ inclined with respect to the longitudinal direction of the inner wall of the laser plug insulating substrate 1 is 5 to 20 °, the optical element 2 is displaced in the longitudinal direction of the inner wall of the laser plug insulating substrate 1. In addition, when the optical element 2 is disposed in the space of the laser plug insulating substrate 1, the optical element 2 can be easily pushed in, which is preferable.

  Further, as in the example shown in FIG. 4, when the groove 1a on the inner wall of the laser plug insulating substrate 1 is formed in a spiral shape substantially perpendicular to the longitudinal direction of the inner wall of the laser plug insulating substrate 1, Even if vibration or the like occurs, the optical element 2 can be effectively suppressed from being displaced in the longitudinal direction of the inner wall of the insulating base 1 for laser plugs. Thus, it is possible to ignite well, which is preferable.

  The groove 1a on the inner wall of the insulating base for laser plug 1 has a depth of 0.1 to 2 μm, a width of 0.1 to 2 μm, and an interval between the grooves 1a of 20 μm or less. Even if the element 2 and the insulating base 1 for laser plugs may expand, the groove 1a on the inner wall of the insulating base 1 for laser plugs causes the optical element 2 to expand to the optical element 2 due to the expansion of the insulating base 1 for laser plugs. The stress can be effectively relaxed, which is preferable.

  Further, the groove 1 a on the inner wall of the laser plug insulating substrate 1 may be formed on the entire inner wall of the laser plug insulating substrate 1 or may be formed only at a position in contact with the optical element 2. Further, the groove 1a may not be formed continuously on the inner wall of the laser plug insulating substrate 1.

  In the present embodiment, as in the example shown in FIG. 1, the condenser lens 3b is provided from the lower end side toward the upper end side, the first resonance mirror 14a is provided on the upper end side, and the second resonance mirror 14b is provided on the lower end side. The optical element 2, the coupling lens 3 a, and the optical fiber 4 are provided inside the laser plug insulating base 1. A housing 12 is provided to hold the laser plug insulating base 1, and the upper end of the laser plug insulating base 1 is provided. A laser plug is obtained by fixing the cap 13 on the side.

The optical fiber 4 held by the laser plug insulating base 1 is held by using a cap 13 in the space of the laser plug insulating base 1 and the upper end side of the laser plug insulating base 1.
Excitation light oscillated from an excitation light source such as a semiconductor laser (LD) provided outside is transmitted.

  The lens 3 held by the laser plug insulating substrate 1 includes a coupling lens 3a and a condenser lens 3b.

  The coupling lens 3 a is for coupling the excitation light transmitted from the optical fiber 4 to the optical element 2, and condenses the excitation light emitted from the optical fiber 4 at the center on the upper end side of the optical element 2. I am letting.

  The condensing lens 3b is for condensing the pulsed light emitted from the optical element 2 at a predetermined position in the combustion chamber, generates plasma having a high energy density, and ignites the air-fuel mixture in the combustion chamber.

The optical element 2 held by the insulating base 1 for laser plugs is a solid laser medium such as YAG (yttrium, aluminum, garnet), YLF (yttrium, lithium, fluoride), YVO ₄ (yttrium vanadate), or the like. And amplifies and pulse-compresses the excitation light incident on the optical element 2, and includes a first resonance mirror 14 a provided on the upper end side of the optical element 2 and a first resonance mirror 14 a provided on the lower end side of the optical element 2. The excitation light incident on the optical element 2 between the two resonance mirrors 14b resonates and is amplified, and pulse light having a high energy density is emitted.

The optical element 2 has a columnar shape, the outer width of the optical element 2 is about 0.5 to 2 mm, and the optical element 2 can be pressed into the through-hole of the insulating base 1 for laser plugs and held well. It has become.

  The optical element 2 has a columnar shape. If the second groove 2a intersects the first groove 1a on the inner wall of the laser plug insulating base 1, the optical element 2 can be used even if vibration or the like occurs. It is possible to prevent the element 2 from being displaced in the longitudinal direction of the inner wall of the insulating base 1 for laser plugs. As a result, it is possible to ignite the air-fuel mixture of the internal combustion engine, which is preferable. Become.

  As in the example shown in FIG. 5, when the second groove 2a on the outer surface of the optical element 2 extends in the columnar longitudinal direction, the optical element 2 is arranged in the space of the insulating base 1 for laser plugs. At the time of installation, the optical element 2 can be easily pushed in, which is preferable.

  The second groove 2a on the outer surface of the optical element 2 is generated from the optical element 2 or the like when the depth is 0.1 to 2 μm, the width is 0.1 to 2 μm, and the interval between the second grooves 2a is 20 μm or less. Even if the optical element 2 and the laser plug insulating base 1 are expanded by the heat generated, the optical element 2 and the laser plug insulating base 1 are expanded by the second groove 2 a of the optical element 2 to the optical element 2. It is possible to effectively relieve the stress, and this is preferable.

  Further, in the laser plug insulating base 1 shown in FIGS. 5 and 6, the groove 1a on the inner wall of the laser plug insulating base 1 is in the longitudinal direction of the inner wall of the laser plug insulating base 1 as in the example shown in FIG. When the first groove 1a on the inner wall of the laser plug insulating substrate 1 and the second groove 2a on the outer surface of the optical element 2 face each other as in the example shown in FIG. The first groove 1a and the second groove 2a that relieve stress due to the thermal expansion difference between the optical element 2 and the laser plug insulating base 1 overlap each other, and the thermal expansion difference between the optical element 2 and the laser plug insulating base 1 is overlapped. This makes it possible to effectively relieve the stress caused by the above.

  Further, as in the example shown in FIG. 6, the first groove 1 a on the inner wall of the insulating base 1 for laser plugs and the second groove 2 a on the outer surface of the optical element 2 are not opposed to each other and are alternately arranged. As a result, stress is less likely to concentrate on the first groove 1a on the inner wall of the insulating base 1 for laser plugs and the second groove 2a on the outer surface of the optical element 2, and the insulating base 1 for laser plugs and the optical element 2 is preferable because cracks and the like are suppressed.

  The housing 12 is for holding the insulating base 1 for laser plugs, and is formed in a substantially cylindrical shape.

  The present invention is not limited to the above-described embodiments, and various modifications can be made. In the above example, the optical element 2, the lens 3, and the optical fiber 4 are held by the integral insulating base 1 for laser plugs. However, they may be held by a plurality of insulating bases 1 for laser plugs. The element 2, the lens 3, and the optical fiber 4 may be held by separate laser plug insulating bases 1, and each laser plug insulating base 1 may be held by the housing 12. With such a configuration, the optical element 2, the lens 3, and the optical fiber 4 in the insulating base 1 for laser plug can be easily aligned, which is preferable.

  According to the laser plug insulating substrate 1 of the present embodiment, the laser plug insulating substrate 1 having a space 11a for holding the optical element 2, the lens 3 and the optical fiber 4 therein. Since the inner wall of each has a groove 1 a, stress due to the difference in thermal expansion between the optical element 2 and the laser plug insulating base 1 is applied to the optical element 2 by the groove 1 a of the inner wall of the laser plug insulating base 1. Can be relaxed, and the characteristics of the optical element 2 can be improved. As a result, the air-fuel mixture of an internal combustion engine such as an automobile engine can be ignited satisfactorily.

  According to the laser plug of the present embodiment, the laser plug insulating base 1 having the above-described configuration and the optical element 2, the lens 3, and the optical fiber 4 held by the laser plug insulating base 1 are used for an automobile. It is possible to improve the ignition of the air-fuel mixture of an internal combustion engine such as an engine.

1... Insulating substrate 1a for laser plug (first) groove
12 .... Housing
13 ... Cap
14a: first resonant mirror
14b ... second resonant mirror 2 ... optical element 2a ... second groove 3 ... lens 3a ... coupling lens 3b ... condensing lens 4 ... optical fiber

Claims (5)

A cylindrical insulating substrate having a space for holding an optical element, a lens and an optical fiber therein,
An insulating substrate for a laser plug, wherein an inner wall of the insulating substrate has a groove.   The insulating base for a laser plug according to claim 1, wherein the groove of the inner wall extends in a longitudinal direction of the inner wall.   The insulating base for a laser plug according to claim 1, wherein the groove of the inner wall is inclined with respect to the longitudinal direction. An insulating base for a laser plug according to claim 1,
A laser plug comprising the optical element, the lens, and the optical fiber housed in the insulating base for laser plug. The groove on the inner wall of the insulating substrate is a first groove;
The laser plug according to claim 4, wherein the optical element has a columnar shape and has a second groove intersecting the first groove.

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