WO2016057556A1

WO2016057556A1 - Structures to insulate ignition system high-voltage within a direct injection gaseous diffusion burn fuel prechamber

Info

Publication number: WO2016057556A1
Application number: PCT/US2015/054297
Authority: WO
Inventors: Chunyi XIA; Robert GLIEGE
Original assignee: Advanced Green Innovations, LLC
Priority date: 2014-10-06
Filing date: 2015-10-06
Publication date: 2016-04-14
Also published as: WO2016057557A1

Abstract

Some embodiments of the invention include a direct-injection igniter. The direct-injector ignitor may include an ignitor shell; an insulator disposed within a portion of the ignitor shell; a prechamber defined at least in part by the ignitor shell and the insulator; and an electrode/valve body disposed within the ignitor shell. In some embodiments, a proximal portion of the electrode/valve body may be disposed within the insulator. In some embodiments, a distal portion of the electrode/valve body may be disposed within the prechamber. In some embodiments, the distal portion of the electrode/valve body comprises at least 25% of the electrode/valve body.

Description

STRUCTURES TO INSULATE IGNITION SYSTEM HIGH-VOLTAGE WITHIN A DIRECT INJECTION GASEOUS DIFFUSION BURN FUEL PRECHAMBER

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Application No. 62/060,348 filed October 6, 2014, entitled "STRUCTURES TO INSULATE IGNITION SYSTEM HIGH- VOLTAGE WITHIN A DIRECT INJECTION GASEOUS DIFFUSION BURN PRECHAMBER," the entirety of which is incorporated into this document for all purposes.

This application claims priority to U.S. Provisional Application No. 62/060,256 filed October 6, 2014, entitled "STRUCTURES AND TECHNIQUES TO FORM REPEATABLE GAS MIXTURES AT SPECIFIC LOCATIONS WITHIN A PRECHAMBER FOR IGNITION AND SUBSEQUENT DIFFUSION FLAME BURN," the entirety of which is incorporated into this document for all purposes.

FIELD

This disclosure relates generally to structures to insulate ignition system high-voltage within a direct injection gaseous fuel prechamber with ignitor.

BACKGROUND

Conventional igniters (or spark plugs) typically include an insulating ceramic that is adjacent and/or bonded to most of or the entire center electrode except for a portion at the distal end of the electrode nearer the intended arc location. This arrangement can provide thermal protection of the center electrode and can provide electrical isolation between the electrode and the igniter body.

SUMMARY

Some embodiments of the invention include a direct-injection igniter. The direct-injector ignitor may include an ignitor shell; an insulator disposed within a portion of the ignitor shell; a prechamber defined at least in part by the ignitor shell and the insulator; and an electrode/valve body disposed within the ignitor shell. In some embodiments, a proximal portion of the electrode/valve body may be disposed within the insulator and a distal portion of the electrode/valve body may be disposed within the prechamber. In some embodiments, the distal portion of the electrode/valve body comprises at least 25% of the electrode/valve body.

In some embodiments, the electrode/valve body may further include a gas injector orifice disposed in the distal portion of the electrode/valve body. In some embodiments, the insulator may include a surface that defines a junction between the insulator and the prechamber, wherein the surface extends from the electrode/valve body to the ignitor shell.

In some embodiments, the surface may define a shape of the insulator that has a triangular cross-section between a portion of the electrode/valve body and the ignitor shell. In some embodiments, the surface may define a shape that has a convex cross-sectional shape between a portion of the electrode/valve body and the ignitor shell. In some embodiments, the surface may define a shape that has a concave cross-sectional shape between a portion of the electrode/valve body and the ignitor shell.

In some embodiments, the insulator may be in continuous contact with the distal portion of the electrode/valve body. In some embodiments, the insulator may be in continuous contact with an inner surface of the ignitor shell.

In some embodiments, the ignitor shell includes one or more orifices providing at least partial fluid communication with the prechamber and an outside chamber (e.g., main chamber).

In some embodiments, the distal portion of the electrode/valve body comprises at least 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, etc. of the entire electrode/valve body. Alternatively and/or additionally, the proximal portion of the electrode/valve body comprises at least 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, etc. of the entire electrode/valve body.

Some embodiments of the invention include a direct-injection igniter comprising an ignitor shell, an electrode/valve body, and an insulator. In some embodiments, the ignitor shell may define a chamber. The ignitor shell may have an upper portion, a middle portion, and a lower portion. The electrode/valve body may have an upper portion (or proximal portion) and a lower portion (or distal portion). In some embodiments, the electrode/valve body may be disposed within the chamber such that the lower portion of the electrode/valve body is disposed within the chamber, and/or the upper portion of the electrode/valve body is disposed within the chamber adjacent with the upper portion of the chamber. In some embodiments, the insulator may be disposed within the chamber between the upper portion of the electrode/valve body and the upper portion of the ignitor shell and the lower portion of the electrode/valve body and the middle portion of the ignitor shell such that a chamber volume is formed between the electrode/valve body near the bottom portion of the electrode/valve body and the insulator.

In some embodiments, the direct-injection igniter may include one or more openings within the ignitor shell disposed in the lower portion of the ignitor shell.

In some embodiments, the insulator may be disposed within the chamber continuously between the upper portion of the electrode/valve body and the upper portion of the ignitor shell.

In some embodiments, the insulator may be disposed within the chamber between the upper portion of the electrode/valve body and the upper portion of the ignitor shell without a volume being formed between the electrode/valve body and the ignitor shell.

In some embodiments, the chamber volume formed between the electrode/valve body near the bottom portion of the electrode/valve body and the insulator increases in size from a middle portion of the electrode/valve body toward the bottom portion of the electrode/valve body.

In some embodiments, the center electrode and fuel valve may be assembly may be configured to inject fuel in to the chamber.

In some embodiments, the chamber volume increases in size from a middle portion of the electrode/valve body toward the bottom portion of the electrode/valve body following a line that intersects with the middle portion of the electrode/valve body with an angle of between 1° and 20°. In some embodiments, the angle may be between 5° and 15°.

These illustrative embodiments are mentioned not to limit or define the disclosure, but to provide examples to aid understanding thereof. Additional embodiments are discussed in the Detailed Description, and further description is provided there. Advantages offered by one or more of the various embodiments may be further understood by examining this specification or by practicing one or more embodiments presented.

BRIEF DESCRIPTION OF THE FIGURES

These and other features, aspects, and advantages of the present disclosure are better understood when the following Detailed Description is read with reference to the accompanying drawings.

Figure 1 is a side view of an injector/ignitor disposed within an engine block.

Figure 2 is a side view of a spark plug.

Figure 3 is a side view of an example igniter with an insulator defined volume.

Figure 4 is a side view of another example igniter with an insulator defined volume according to some embodiments.

Figure 5 is a cross-sectional top view of an example igniter with an insulator defined volume according to some embodiments.

Figure 6 illustrates the ignitor coupled with an injector-igniter assembly. Figure 7 is a side view of an example igniter with an insulator defined volume according to some embodiments.

Figure 8 is a side view of an example igniter with an insulator defined volume according to some embodiments.

Figure 9 is a side view of an example igniter with an insulator defined volume according to some embodiments.

Figure 10 is a side view of an example igniter with an insulator defined volume according to some embodiments.

Figure 11 is a side view of an example igniter with an insulator defined volume according to some embodiments.

Figure 12 is a side view of an example igniter with an insulator defined volume according to some embodiments.

Figure 13 is a side view of an example igniter with an insulator defined volume according to some embodiments.

Figure 14 is a graph showing the reduced thermal loading on the electrode in a gaseous direct-injection igniter that utilizes ignition within a prechamber.

DETAILED DESCRIPTION

This application relates generally to high-voltage containment and prechamber volume definition within a gaseous direct-injection fuel injector/igniter that may be used in an existing heavy duty diesel engine modified to use alternative fuels such as, for example, natural gas or other fuels.

Embodiments of the invention include an injector/ignitor that may be used in a direct- injection and/or diffusion-burn prechamber ignition system. Such systems may rely on precise control of fluids and may use high voltage ignition sources. Because standard ignition sources, such as spark plugs, ignite homogenous fuel mixtures they can be and are typically installed directly into a main combustion chamber. In prechamber ignition systems, the prechamber may be exposed to extremely high temperatures (e.g., temperatures greater than 500° C) for relatively long durations (for example, more than 20 crank angle degrees) due to the combustion event and resulting hot exhaust gases (for example, greater than 200° C, for approximately 345 crank angle degrees). Because of these extreme conditions, standard ignition devices are designed to protect center electrodes from heat and dissipate thermal energy quickly in addition to providing ignition high voltage isolation.

As shown and described in Figure 2 (see below), conventional igniters (e.g., spark plugs) utilize an insulator adjacent and/or bonded to nearly the entire center electrode except at the intended arc location (or ignition gap). Such arrangements can provide thermal protection of the center electrode by shielding and dissipating heat away from the electrode and can aid in the high voltage isolation within a combustion volume. Thus, only a very small portion of the distal end of the center electrode is not in contact with the insulator. In some gaseous direct-injection igniters (or other ignitors, for example, that utilize ignition within a prechamber) and/or diffusion burn strategies, the thermal loading on the electrode may be lower than in standard spark plug configurations. In some embodiments, insulators in prechamber ignition systems may be used to contain high-voltages and/or form prechamber volume structure while providing a variety of prechamber designs.

Figure 1 is a side view of an injector/ignitor 100 disposed within an engine head 120. The injector/ignitor 100 includes a prechamber 110. Generally speaking, the prechamber may be a volume within the injector/ignitor 100 that allows for idealized mixture of air and fuel (e.g., a near stoichiometric mixture) for ignition within the prechamber, which may then cause ignition in the main chamber 115 that may, in some embodiments, have a lean fuel- air mixture (e.g., λ = 1.0) or an extreme lean fuel-air mixture (Λ = 1.5). The use of a prechamber, in such embodiments may be useful to initiate ignition of a lean fuel-air mixture in the main chamber when initiation of such a lean fuel-air mixture may not be possible otherwise.

The main chamber 115 may be a volume defined by the engine block 105, the engine head 120, and the piston 125. Intake valve 130 and exhaust valve 135 may also be disposed within the engine head 120 and may provide intake and/or exhaust channels to and/or from the main chamber 115.

Figure 2 is a side view of a typical spark plug 200. The spark plug 200 is placed within the engine head 120 so that it may ignite a fuel-gas mixture within the main chamber 115. The spark plug 200, however, does not include a prechamber. A typical spark plug 200 may include an electrode 205 disposed within an ignitor housing 215. An insulator 210 may be disposed between the electrode 205 and the ignitor housing 215. The insulator 210 may provide electrical insulation between the electrode 205 and the ignitor housing 215. The electrical insulation, for example, can be used to limit the electrical discharge through the insulator 210 between the electrode 205 and the ignitor housing 215 (or ground) except at the ignition gap 230. To achieve this, the insulator 210 is disposed continuously between the electrode 205 and the ignitor housing 215 except at the distal end of the electrode to ensure an ignition event (e.g., spark, high voltage, etc.) occurs at the ignition gap 230. As shown, there are no gaps, volumes, chambers, etc. radially between the electrode 205 and the insulator 210.

In Figure 2, the electrode exposure height, which is the distance between the distal end of the electrode 205 and the distal end of the insulator 120, is labeled H. The gap height, which is the distance between where the insulator 120 is disposed continuously across a radius between the electrode 120 and the ignitor housing 215 and the distal end of the electrode 205, is labeled h, which is also the height of the gap formed between the insulator 120 and the ignitor housing 215. The ratio of the gap height, h, and the electrode exposure height, H, (J¹/ fj) can be a value less than or equal to 0.2, 0.1 , 0.05, etc.

Figure 3 is a side view of an example igniter 300 with an insulator defined volume 350 according to some embodiments. The insulator defined volume 350, for example, may be part of the prechamber 1 10 in the volume adjacent to the ignition gap 230. The insulator defined volume 350, for example, may be part of the prechamber 1 10 in the volume adjacent to the distal electrode/valve body portion 330B of the electrode/valve body 330. The ignitor 300 may be disposed within engine block 105 with the distal end of the ignitor 300 extending into the main chamber 1 15. An ignition event triggered by an electrode may occur within the prechamber 1 10 igniting the fuel within the prechamber. The ignition of the fuel within the prechamber 1 10 may be expelled into the main chamber causing the fuel within the main chamber to ignite.

The ignitor 300 includes an ignitor body 315 (e.g., ignitor shell), an electrode/valve body 330, an electrode, and a valve 340, which, for example, may generally be referred to as an electrode/valve body. Fuel may be introduced into the prechamber 1 10 from the fuel inlet 332 by opening the valve 340. The valve 340 shown in Figure 3, for example, is an inward opening valve. In some embodiments, the valve 340 may be an outward opening valve. The ignitor body 315 may include an upper ignitor body portion 315A, a middle ignitor body portion 315B, and a lower ignitor body portion 315C. In some embodiments, the lower ignitor body portion 315C may include a portion of the ignitor body 315 nearest the prechamber 1 10. In some embodiments, the lower ignitor body portion 315C may enclose all or portions of the prechamber and/or may extend into the main chamber 1 15. In some embodiments, the lower ignitor body portion 315C may include one or more channels, gaps, orifices, or holes that may connect the prechamber 1 10 and the main chamber 1 15. In some embodiments, the middle ignitor body portion 315B may include a portion of the ignitor body 315 between the upper ignitor body portion 315A and the lower ignitor body portion 315C. In some embodiments, the middle ignitor body portion 315B may include a portion of the ignitor body 315 in the region near the ignition gap 230. In some embodiments, the upper ignitor body portion 315A may include portions that extend outside the engine block 105.

In some embodiments, the electrode and the valve body 330, the insulator 335, and/or the electrode/valve body 110 may be disposed within the ignitor body 315. In this example, the prechamber nozzle 360 form an orifice through which ignition may spread from the prechamber 110 into the main chamber 115. In addition, during a compression cycle, air may be forced from the main chamber 115 into the prechamber 110 through the prechamber nozzle 360. In some embodiments, a plurality of prechamber nozzles may be included.

In some embodiments, the electrode/valve body 330 may have a distal electrode/valve body portion 330B and/or a proximal electrode/valve body portion 330A. In some embodiments, the distal electrode/valve body portion 330B may be disposed near the ignition gap 230. In some embodiments, the proximal electrode/valve body portion 330A may include portions that extend outside the engine block 105.

The ignitor 300 may include an insulator 335 that fills the volume defined by the upper ignitor body portion 315A between the proximal electrode/valve body 330 A and the inner surface of the ignitor body 315. The insulator 335 may include a ceramic such as, for example, alumina (e.g., 74% - 99.9%), silicon nitride, macor, aluminum nitride, silicon nitride, silicon carbide, zirconia, stealite, etc. The insulator may continuously fill the volume defined by the ignitor body 315 between the electrode/valve body 330 and the inner surface of the ignitor body 315 except for the insulator defined volume 350 found along the electrode/valve body 330 near the distal electrode/valve body portion 330B. In some embodiments, the insulator defined volume 350 may form part of the prechamber 110. As such, during operation, for example, fuel and air may mix within the insulator defined volume 350 and the prechamber 110 and may be ignited when an ignition event occurs between the electrode/valve body 330 and ground 325 or the ignitor body 315 As shown in the figure, the insulator 335 continuously fills the space between the proximal electrode/valve body portion 330A and the upper ignitor body portion 315 A. The insulator 335 may be in direct contact with the proximal electrode/valve body portion 330A of the electrode/valve body 330 and/or may be in direct contact with the upper ignitor body portion 315A of the ignitor body 315. The three-dimensional shape of the insulator 335 may be such that the insulator 335 may not be in contact with the distal electrode/valve body portion 33 OB of the electrode/valve body 330 but may be in contact with a portion of the electrode/valve body 330 disposed between the distal electrode/valve body portion 330B and the proximal electrode/valve body portion 330A. In some embodiments, the insulator 335 may be in continuous contact with the interior wall of the ignitor body 315 between the middle ignitor body portion 315B and the upper ignitor body portion 315 A. In some embodiments, the insulator 335 may be in continuous contact with a proximal portion of the electrode/valve body 330 from the proximal end of the electrode/valve body portion 330A to a point between the distal electrode/valve body portion 330B and the proximal electrode/valve body portion 330A. In some embodiments, the insulator 335 may extend away or may not be in contact with a distal portion of the distal electrode/valve body portion 330B of the electrode/valve body 330 from a point between the distal electrode/valve body portion 330B and the proximal electrode/valve body portion 330A forming the insulator defined volume 350. The proximal portion of the electrode/valve body 330 may comprise 90%, 85%, 80%, 75%, 70%, 65%, 60%, 55%, 50%, 45%, 40%, etc. of the electrode/valve body 330. In some embodiments, the insulator 335 may extend away from the distal electrode/valve body portion 330B of the electrode/valve body 330 at a position between the distal electrode/valve body portion 330B and the proximal electrode/valve body portion 330A along an angle β, where, for example, 1° < β < 20°. The range of angles may include, for example: 1° < β < 179°, 1° < β < 90°; 2° < β < 5°; 5° < β < 15°; 10° < β < 15°; 1° < β < 10°; 10° < β < 20°, 2° < β < 45°; and 5° < β < 15°.

In some embodiments, the insulator defined volume 350 may have a triangular cross- sectional shape as shown in Figure 3.

In some embodiments, because more fuel and air are provided near the ignition gap 230 and/or at the insulator defined volume 350, the total volume of the prechamber 110 including the insulator defined volume 350, can be designed with a lower overall volume. In some embodiments, the insulator 335 may have a surface 336 that defines the shape and/or size of the insulator defined volume 350. A cross-section surface length, L, from the electrode/valve body 330 to the ignitor body 315 may be defined by L_S = D-_L +

^²/ ₃1_ηβ· ^m some embodiments, the cross-section surface length, L, may be less than 10 mm. In some embodiments, the cross-section surface length, L_s, may be less than 6 mm. In some embodiments, the cross-section surface length, L_s, may be less than 4 mm. In some embodiments, the cross-section surface length, L_s, may be defined by L_S = ^/Q, V is the voltage at the electrode and Q is a constant that may vary based on application, environment, fuel mixture, fuel type, ceramic type, etc. Thus, "/Q = D₁ + ²/₈ι_ηβ-

In some embodiments, the shape of the insulator 335 defining the insulator defined volume 350 may provide a longer cross-section surface length, which may result in a longer surface path an arc may travel over the surface 336 between the igniter body 315 and the electrode/valve body 330. The longer the longer cross-section surface length, the less likely that an arc may propagate along the surface of the insulator 335.

The shape of the insulator 335 and/or the insulator defined volume 350 may have any number of shapes, examples of which can be found in Figures 4 and 7-13.

Any type of electrode and/or valve may be used in any of the embodiments described in this document. The valve, for example, may be an inward opening valve or an outward opening valve.

In some embodiments, the insulator defined volume 350 may provide electric insulation between the electrode/valve body 330 and the ignitor body 315. In some embodiments, the insulator defined volume 350 may act as a thermal compensator to allow the electrode/valve body 330 to heat up when the volume fills with hot gases or fluids from the main chamber 115. The graph shown in Figure 14 illustrates the reduced thermal loading on the electrode using some embodiments of the invention.

Moreover, in some embodiments, the insulator defined volume 350 may provide a number of benefits. For example, the insulator defined volume 350 may provide high voltage insulation. As another example, the insulator defined volume 350 may provide reduced heat shielding of the electrode/valve body 330, which may be useful to compensate for heat rejected from the fuel injection process. As another example, the insulator defined volume 350 may be shaped to encourage or improve fuel-air mixing.

As another example, the insulator defined volume 350 may be shaped to increase ignition kernel growth. For instance, the volume of the prechamber 110 (and/or the insulator defined volume 350 or any insulator defined volume disclosed in this document) above the primary ignition gap 230 can determine how much fluid flows by and/or mixes with the fluid surrounding the primary ignition gap 230. Because pressure is the same regardless of the size of the prechamber and/or the insulator defined volume 350, a larger volume may require more fluid to make the pressure increase in comparison to a smaller volume. As another example, the shape, surface area, material properties and/or temperature of structures surrounding the ignition kernel can obstruct kernel growth as combustion occurs and/or can remove thermal energy from the ignition kernel. In some embodiments, the insulator defined volume 350 may create volumetric efficiency within the prechamber. For example, a prechamber with an insulator defined volume 350 (or any insulator defined volume disclosed in this document) can allow for the portions of the prechamber 110 other than the insulator defined volume 350 to have a greater volume, which may improve the mixing of fuel and air within the prechamber.

The electrode exposure height, which is the distance between the distal end of the igniter body 330 and the distal end of the insulator 335, is labeled H. The gap height, which is the distance between where the insulator 335 is disposed continuously across a radius between the igniter body 330 and the ignitor housing 315 and the distal end of the igniter body 330, is labeled h, which is also the height of the gap formed between the insulator 335 and the ignitor housing 315. The ratio of the gap height, h, and the electrode exposure height, H, is one

Figure 4 is a side view of an example igniter 400 with an insulator defined volume 450 according to some embodiments. In this example, the insulator defined volume 450 has a geometry with a rectangular cross-sectional shape. For example, the insulator defined volume 450 may form a shape with a rectangular cross-section that starts at a position between the distal electrode/valve body portion 330B and the proximal electrode/valve body portion 330A and extends a radial distance Di toward the distal electrode/valve body portion 330B as shown in Figure 4. The insulator 435 may have a cross-sectional shape having the rectangular cross-section of the insulator defined volume 450 cut from the insulator 435. The insulator 435 may extend radially a distance D₂ from the inner wall of the igniter body 330.

Figure 5 is a cross-sectional top view of ignitor 300 cut along section A (or igniter 400 cut along section A) according to some embodiments. The ignitor 300 includes an insulator defined volume 350 according to some embodiments. The ignitor body 315 forms a cavity within which the electrode/valve body 330, the insulator 335, the insulator defined volume 350, the valve 340, and the fuel inlet 332 are disposed. At this cross-section of the ignitor 300 (or igniter 400), the insulator 335 may not be in contact with the electrode/valve body 330 forming the insulator defined volume 350. Instead, at this cross-section of the ignitor 300 the insulator 335 is in contact with the ignitor body 315.

Figure 6 illustrates the ignitor 300 coupled with an injector-igniter 600. The ignitor 300 includes the ignitor body 315 and an injector body 604 having connections for a high voltage ignition driver 606, gaseous fuel port 608, and an injector-actuator control signal. The injector-igniter 600 may provide a mechanism to precisely meter the amount of gaseous fuel charge. In same embodiments, the amount of gaseous fuel charge may be metered by either an inward opening valve or an outward opening valve. The motion of valve 340 can be controlled directly or indirectly in the longitudinal direction of the injector-igniter 600 with an actuator 610. In some embodiments, the actuator 610 may include one or more of a piezoelectric stack(s), solenoid coil(s), hydraulic fluid, magnetorestrictive devices, or any combination thereof. The primary ignition gap 230 is isolated by insulator 335 and/or dielectric gaseous fuel to the inside of the body 604 along the length of the injector from the valve 340 to the fuel port 608. Ignition may be powered using an ignition driver connected to the injector-igniter 600 at the high voltage ignition driver 606 and may or may not include a standard spark ignition, corona discharge, laser, microwave, or other suitable energy source. The high voltage assembly may be concentrically, coaxially, or off-set located relative to the fuel valve. The ignition gap 230 can also be located off-set, concentrically or coaxially to the longitudinal axis or in numerous locations within the prechamber 110 based on performance optimization, The performance of the ignition can be optimized by combination of computational fluid dynamic modeling and engine testing on a single cylinder engine to evaluate ignition kernel growth, pre-chamber pressure buildup, turbulent, reactive jet intensity, and main chamber flame propagation and rate of heat release, The injector-igniter 600 may include a body having a connection for the high voltage ignition driver, a connection to receive control signals from the injector driver and the fuel port to receive fuel from a tank.

Figure 7 is a side view of an example igniter 700 with an insulator defined volume 750 according to some embodiments that may be similar to the insulator defined volume 350 shown in Figure 3. In this example, the insulator defined volume 750 has a triangular cross-sectional shape. In this example, the insulator 735 may be continuously disposed between the ignitor body 315 and the electrode/valve body 330 at the proximal end of the ignitor body 315 and/or the proximal end of the electrode/valve body 330. In this example, the insulator 735 may be in continuous contact with the inner surface of the proximal end of the ignitor body 315 and the middle portion of the ignitor body 315. In this example, the insulator 735 may be in continuous contact with the outer surface of the proximal end of the electrode/valve body 330. The insulator defined volume 750 may include a volume within the ignitor body 315 that is adjacent to and/or includes the distal portion of the electrode/valve body 330.

For a portion of the distal end of the electrode/valve body 330 (e.g., a portion nearer the ignition gap 230) the insulator 735 may not be in contact with the outer surface of the electrode/valve body 330. The insulator 735 may have a shape with a cross-section that includes a surface 736 that slopes away from the electrode/valve body 330 with an angle β. For example, the surface 736 of the insulator may be sloped from the electrode/valve body 330 toward the ignitor body 315 in a direction toward the prechamber 110. The angle β, for example, may be 1° < β < 20°. As other examples, the range of angles may include: 2° < β < 5°; 5° < β < 15°; 10° < β < 15°; 1° < β < 10°; 10° < β < 20°, and 5° < β < 15°. The shape of the insulator 735 can form the insulator defined volume 750 as part of the prechamber 110 near the ignition gap 230.

Figure 8 is a side view of an example igniter 800 with an insulator defined volume 850 according to some embodiments. In this example, the insulator defined volume 850 has a modified triangular cross-sectional shape. In this example, the insulator 835 may be continuously disposed between the ignitor body 315 and the electrode/valve body 330 at the proximal end of the ignitor body 315 and/or the proximal end of the electrode/valve body 330. In this example, the insulator 835 may be in continuous contact with the inner surface of the proximal end of the ignitor body 315 and the middle portion of the ignitor body 315. In this example, the insulator 835 may be in continuous contact with the outer surface of the proximal end of the electrode/valve body 330. The insulator defined volume 850 may include a volume within the ignitor body 315 that is adjacent to and/or includes the distal portion of the electrode/valve body 330.

For a portion of the distal end of the electrode/valve body 330 (e.g., a portion nearer the ignition gap 230) the insulator 835 may not be in contact with the outer surface of the electrode/valve body 330. The insulator 835 may have a shape with a cross-section that includes a surface 836 that steeply angles away from the electrode/valve body 330 with an angle β in a direction toward the prechamber 110 and then, toward the proximal end of the electrode/valve body 330, the surface 836 shallowly angles toward the ignitor body 315 with an angle a in a direction toward the prechamber 110. The angle β, for example, may be 1° < β < 10°. The angle β, for example, may have a value between one of the following ranges: 1° < β < 5°; and 5° < β < 10°. The angle a, for example, may be 75° < a < 90° with respect to either or both the electrode/valve body 330 and the ignitor body 315. The angle a, for example, may have a value between one of the following ranges: 45° < a < 90°; 75° < a < 90°; 50° < a < 80°; and 80 < a < 85°.

The insulator defined volume 850 is formed and/or defined by the shape and/or design of the insulator 835. Figure 9 is a side view of an example igniter 900 with an insulator defined volume 950 according to some embodiments. In this example, the insulator defined volume 950 has a rectangular cross-sectional shape that may be similar to the insulator defined volume 450 shown in Figure 4.

In this example, the insulator 935 may be continuously disposed between the ignitor body 315 and the electrode/valve body 330 at the proximal end of the ignitor body 315 and/or the proximal end of the electrode/valve body 330. In this example, the insulator 935 may be in continuous contact with the inner surface of the proximal end of the ignitor body 315 and the middle portion of the ignitor body 315. In this example, the insulator 935 may be in continuous contact with the outer surface of the proximal end of the electrode/valve body 330. The insulator defined volume 950 may include a volume within the ignitor body 315 that is adjacent to and/or includes the distal portion of the electrode/valve body 330.

For a portion of the distal end of the electrode/valve body 330 (e.g., a portion nearer the ignition gap 230) the insulator 935 may not be in contact with the outer surface of the electrode/valve body 330. The insulator 935 may have a shape with a cross-section that includes a surface 936 that is substantially parallel (e.g., within ±1°, ±2°, ±5°, etc.) with the electrode/valve body 330 and/or the proximal portion of the ignitor body 315. The insulator 935 may have a shape with a cross-section that includes a surface 937 that is sloped toward the ignitor body 315 at an angle a. The angle a, for example, may have a value between one of the following ranges: 75° < a < 90° and 80 < a < 85°.

Figure 10 is a side view of an example igniter 1000 with an insulator defined volume 1050 according to some embodiments. In this example, the insulator defined volume 1050 has a concave cross-sectional shape. As shown in the figure, the concave cross-sectional shape of the prechamber volume 1050 has a portion of the insulator defined volume 1050 that extends toward the proximal end of the ignitor body 315 and/or the proximal end of the electrode/valve body 330. Alternatively or additionally, the insulator 1035 may have a surface 1036 that extends downward toward the distal end of the ignitor body 315.

In this example, the insulator 1035 may be continuously disposed between the ignitor body 315 and the electrode/valve body 330 at the proximal end of the ignitor body 315 and/or the proximal end of the electrode/valve body 330. In this example, the insulator 1035 may be in continuous contact with the inner surface of the proximal end of the ignitor body 315 and the middle portion of the ignitor body 315. In this example, the insulator 1035 may be in continuous contact with the outer surface of the proximal end of the electrode/valve body 330. For a portion of the distal end of the electrode/valve body 330 (e.g., a portion nearer the ignition gap 230) the insulator 1035 may not be in contact with the outer surface of the electrode/valve body 330. The insulator defined volume 1050 may include a volume within the ignitor body 315 that is adjacent to and/or includes the distal portion of the electrode/valve body 330.

The electrode exposure height, which is the distance between the distal end of the igniter body 330 and the distal end of the insulator 1035, is labeled H. The gap height, which is the distance between where the insulator 1035 is disposed continuously across a radius between the igniter body 330 and the ignitor housing 315 and the distal end of the igniter body 330, is labeled h, which is also the maximum height of the gap formed between the insulator 1035 and the ignitor housing 315. The ratio of the gap height, h, and the electrode exposure height, H, may be greater than or equal to three tenths ( —

Figure 11 is a side view of an example igniter 1100 with an insulator defined volume 1150 according to some embodiments. In this example, the insulator defined volume 1150 has a convex cross-sectional shape. As shown in the figure, the insulator 1135 may have a surface 1136 that bulges downward toward the distal end of the ignitor body 315.

In this example, the insulator 1035 may be continuously disposed between the ignitor body 315 and the electrode/valve body 330 at the proximal end of the ignitor body 315 and/or the proximal end of the electrode/valve body 330. In this example, the insulator 1135 may be in continuous contact with the inner surface of the proximal end of the ignitor body 315 and the middle portion of the ignitor body 315. In this example, the insulator 1 135 may be in continuous contact with the outer surface of the proximal end of the electrode/valve body 330. For a portion of the distal end of the electrode/valve body 330 (e.g., a portion nearer the ignition gap 230) the insulator 1135 may not be in contact with the outer surface of the electrode/valve body 330. The insulator defined volume 1150 may include a volume within the ignitor body 315 that is adjacent to and/or includes the distal portion of the electrode/valve body 330.

Figure 12 is a side view of an example igniter 1200 with an insulator defined volume 1250 according to some embodiments. In this example, the insulator defined volume 1250 has a concave cross-sectional shape. As shown in the figure, the concave cross-sectional shape of the prechamber volume 1250 has a portion of the insulator defined volume 1250 that extends toward the proximal end of the ignitor body 315 and/or the proximal end of the electrode/valve body 330. Alternatively or additionally, the insulator 1235 may have a surface 1236 that extends downward toward the distal end of the ignitor body 315.

In this example, the insulator 1235 may be continuously disposed between the ignitor body 315 and the electrode/valve body 330 at the proximal end of the ignitor body 315 and/or the proximal end of the electrode/valve body 330. In this example, the insulator 1235 may be in continuous contact with the inner surface of the proximal end of the ignitor body 315 and the middle portion of the ignitor body 315. In this example, the insulator 1235 may be in continuous contact with the outer surface of the proximal end of the electrode/valve body 330. For a portion of the distal end of the electrode/valve body 330 (e.g., a portion nearer the ignition gap 230) the insulator 1235 may not be in contact with the outer surface of the electrode/valve body 330. The insulator defined volume 1250 may include a volume within the ignitor body 315 that is adjacent to and/or includes the distal portion of the electrode/valve body 330.

The electrode exposure height, which is the distance between the distal end of the igniter body 330 and the distal end of the insulator 1235, is labeled H. The gap height, which is the distance between where the insulator 1235 is disposed continuously across a radius between the igniter body 330 and the ignitor housing 315 and the distal end of the igniter body 330, is labeled h, which is also the maximum height of the gap formed between the insulator 1235 and the ignitor housing 315. The ratio of the gap height, h, and the electrode exposure height, H, may be greater than or equal to three tenths (e.g., ^¹/^≥ 0.3).

Figure 13 is a side view of an example igniter 1300 with an insulator defined volume 1350 according to some embodiments. In this example, insulator 1335 has a jagged and/or saw- toothed cross-sectional shape. The surface 1336 of the insulator 1335 may be roughly angled, convex, or concave as shown in Figures 3, 4, and/or 7-13 and may have one or more of the characteristics described in regard to these figures. Additionally or alternatively, the insulator 1335 may have a jagged and/or saw-toothed shaped surface 1336.

The term "substantially" means within 5% or 10% of the value referred to or within manufacturing tolerances.

Various embodiments are disclosed. The various embodiments may be partially or completely combined to produce other embodiments.

Numerous specific details are set forth herein to provide a thorough understanding of the claimed subject matter. However, those skilled in the art will understand that the claimed subject matter may be practiced without these specific details. In other instances, methods, apparatuses, or systems that would be known by one of ordinary skill have not been described in detail so as not to obscure claimed subject matter.

The use of "adapted to" or "configured to" herein is meant as open and inclusive language that does not foreclose devices adapted to or configured to perform additional tasks or steps. Additionally, the use of "based on" is meant to be open and inclusive, in that a process, step, calculation, or other action "based on" one or more recited conditions or values may, in practice, be based on additional conditions or values beyond those recited. Headings, lists, and numbering included herein are for ease of explanation only and are not meant to be limiting.

While the present subject matter has been described in detail with respect to specific embodiments thereof, it will be appreciated that those skilled in the art, upon attaining an understanding of the foregoing, may readily produce alterations to, variations of, and equivalents to such embodiments. Accordingly, it should be understood that the present disclosure has been presented for-purposes of example rather than limitation, and does not preclude inclusion of such modifications, variations, and/or additions to the present subject matter as would be readily apparent to one of ordinary skill in the art.

Claims

CLAIMS That which is claimed:

1. A direct-injection igniter comprising:

an ignitor shell defining a chamber, the ignitor shell having an upper portion, a middle portion, and a lower portion;

an electrode/valve body having an upper portion and a lower portion, the electrode/valve body disposed within the chamber such that the lower portion of the electrode/valve body is disposed within the chamber, and the upper portion of the electrode/valve body is disposed within the chamber adjacent with the upper portion of the chamber; and

an insulator disposed within the chamber between the upper portion of the electrode/valve body and the upper portion of the ignitor shell and between the lower portion of the electrode/valve body and the middle portion of the ignitor shell such that a chamber volume is formed between the electrode/valve body and the bottom portion of the electrode/valve body and the insulator such that the electrode/valve body may operate in the presence of reduced thermal loads.

2. The direct-injection igniter according to claim 1 , further comprising an opening within the ignitor shell disposed in the lower portion of the ignitor shell.

3. The direct-injection igniter according to claim 1, wherein the insulator is disposed within the chamber continuously between the upper portion of the electrode/valve body and the upper portion of the ignitor shell.

4. The direct-injection igniter according to claim 1, wherein the insulator is disposed within the chamber between the upper portion of the electrode/valve body and the upper portion of the ignitor shell without a volume being formed between the electrode/valve body and the ignitor shell.

5. The direct-injection igniter according to claim 1, wherein the chamber volume formed between the electrode/valve body near the bottom portion of the electrode/valve body and the insulator increases in size from a middle portion of the electrode/valve body toward the bottom portion of the electrode/valve body.

6. The direct-injection igniter according to claim 1, wherein the electrode/valve body is configured to inject fuel into the chamber.

7. The direct-injection igniter according to claim 1, wherein the chamber volume increases in size from a middle portion of the electrode/valve body toward the bottom portion of the electrode/valve body following a line that intersects with the middle portion of the electrode/valve body with an angle of between 1° and 20°.

8. The direct-injection igniter according to claim 7, wherein the angle is between 5° and 15°.

9. A direct-injection igniter comprising:

an ignitor shell;

an insulator disposed within a portion of the ignitor shell; a prechamber defined at least in part by the ignitor shell and the insulator; and

an electrode/valve body disposed within the ignitor shell, a proximal portion of the electrode/valve body disposed within the insulator and a distal portion of the electrode/valve body disposed within the prechamber, wherein the distal portion of the electrode/valve body comprises at least 25% of the electrode/valve body such that the distal portion electrode body is exposed to an environment within the prechamber.

10. The direct-injection igniter according to claim 9, wherein the electrode/valve body further comprises a fuel injector orifice disposed in the distal portion of the electrode/valve body.

11. The direct-injection igniter according to claim 9, wherein the insulator comprises a surface that defines a junction between the insulator and the prechamber, wherein the surface extends from the electrode/valve body to the ignitor shell.

12. The direct-injection igniter according to claim 11, wherein the surface defines a shape of the insulator that has a triangular cross-section between a portion of the electrode/valve body and the ignitor shell.

13. The direct-injection igniter according to claim 11, wherein the surface defines a shape of the insulator that has a convex cross-sectional shape between a portion of the electrode/valve body and the ignitor shell.

14. The direct-injection igniter according to claim 9, wherein a surface of the insulator defines a shape of the insulator that has a concave cross-sectional shape between a portion of the electrode/valve body and the ignitor shell.

15. The direct-injection igniter according to claim 9, wherein the insulator is in continuous contact with the distal portion of the electrode/valve body.

16. The direct-injection igniter according to claim 9, wherein the insulator is in continuous contact with an inner surface of the ignitor shell.

17. The direct-inj ection igniter according to claim 9 , wherein the ignitor shell comprises one or more orifices providing at least partial fluid communication with the prechamber and an outside chamber.

18. The direct-injection igniter according to claim 9, wherein the distal portion of the electrode/valve body comprises at least 50% of the electrode/valve body.

19. The direct-injection igniter according to claim 9, wherein at least 50% of the electrode/valve body is not in contact with the insulator.