Patent Grant
10931087
This application is a National Stage of International Application No. PCT/JP2017/010226, filed Mar. 14, 2017, claiming priority based on Japanese Patent Application No. 2016-153660, filed Aug. 4, 2016.
The present specification relates to an ignition plug.
An ignition plug is used to ignite air-fuel mixture in a combustion chamber of an internal combustion engine or the like. The ignition plug includes, for example, a tubular insulator, and a metallic shell disposed around the outer circumference of the insulator. In such an ignition plug, for example, the metallic shell has an external thread formed on an outer circumferential surface thereof. The external thread of the metallic shell is engaged with an internal thread formed on a mounting hole of the internal combustion engine.
Patent Document 1: Japanese Patent Application Laid-Open (kokai) No. 2009-245716
In order to improve the degree of freedom for design of an internal combustion engine, a reduction in the diameter of an ignition plug is preferred. However, as a result of reduction in the ignition plug diameter, defects have arisen in some cases. For example, in some cases, deterioration in thermal resistance has arisen.
The present specification discloses a technique for restraining defects regarding an ignition plug.
The present specification discloses, for example, the following application examples.
An ignition plug comprising:
a tubular insulator having an axial hole extending in a direction of an axial line;
a metallic shell disposed around an outer circumference of the insulator;
a center electrode disposed in the axial hole of the insulator; and
a ground electrode connected to a forward end of the metallic shell and facing the center electrode,
wherein the metallic shell has a threaded portion to be engaged with a thread ridge of a mounting hole of an internal combustion engine, and
a relational expression Ss/(Sa+Sb)≥2.6 is satisfied,
where Ss is a surface area of an outer circumferential surface of the metallic shell extending from a rear end of the threaded portion to a forward end of the threaded portion,
Sa is a surface area of that portion of the metallic shell which is to be exposed to combustion gas of the internal combustion engine; and
Sb is a surface area of that portion of the insulator which is to be exposed to the combustion gas.
According to this configuration, thermal resistance can be improved.
An ignition plug according to application example 1, wherein
the metallic shell has an inside-diameter-reducing portion whose inside diameter reduces toward a forward-end side;
the insulator has an outside-diameter-reducing portion whose outside diameter reduces toward the forward-end side;
the ignition plug has a packing in contact with the outside-diameter-reducing portion and with the inside-diameter-reducing portion, or the outside-diameter-reducing portion is in direct contact with the inside-diameter-reducing portion; and
a relational expression F≥5.0 mm is satisfied,
where F is a distance in the direction of the axial line from a forward end of a contact portion between the outer circumferential surface of the insulator and the inside-diameter-reducing portion or the packing to the forward end of the metallic shell.
According to this configuration, since a change in temperature is restrained at a contact portion of the outer circumferential surface of the insulator with the inside-diameter-reducing portion or with the packing, durability can be improved.
An ignition plug according to application example 1 or 2, wherein
the metallic shell has an inside-diameter-reducing portion whose inside diameter reduces toward the forward-end side;
the insulator has an outside-diameter-reducing portion whose outside diameter reduces toward the forward-end side;
the ignition plug has a packing in contact with the outside-diameter-reducing portion and with the inside-diameter-reducing portion, or the outside-diameter-reducing portion is in direct contact with the inside-diameter-reducing portion; and
a relational expression (Vv−Vc)≤2,000 mm3 is satisfied,
where Vv is a volume of a forward-side portion of the metallic shell extending from a rear end of the threaded portion to a forward end of the metallic shell and assumed to be solid, and
Vc is a volume of that portion of a space between an inner circumferential surface of the metallic shell and an outer circumferential surface of the insulator, which portion is located on the forward-end side of a forward end of a contact portion between the outer circumferential surface of the insulator and the inside-diameter-reducing portion or the packing.
According to this configuration, fouling resistance can be improved.
An ignition plug according to any one of application examples 1 to 3, wherein
the metallic shell has an inside-diameter-reducing portion whose inside diameter reduces toward the forward-end side;
the insulator has an outside-diameter-reducing portion whose outside diameter reduces toward the forward-end side;
the ignition plug has a packing in contact with the outside-diameter-reducing portion and with the inside-diameter-reducing portion, or the outside-diameter-reducing portion is direct contact with the inside-diameter-reducing portion;
a forward-end-side portion of the insulator is disposed on the forward-end side of a forward end of the metallic shell; and
a relational expression Sd/Se≤0.46 is satisfied,
where Sd is a projected area of that portion of the insulator which is disposed on the forward-end side of the forward end of the metallic shell and is projected in a direction perpendicular to the direction of the axial line, and
Se is a sectional area of the insulator taken perpendicularly to the direction of the axial line at a forward end of a contact portion between the outer circumferential surface of the insulator and the inside-diameter-reducing portion or the packing.
According to this configuration, durability can be improved.
A control system for controlling an internal combustion engine having an ignition plug according to any one of application examples 1 to 4 and a coolant passage for cooling the ignition plug, comprising:
a flow control section for controlling a flow per unit time of coolant flowing through the coolant passage; and
a temperature sensor for measuring temperature of the internal combustion engine,
wherein if the temperature measured by the temperature sensor is equal to or less than a threshold value, the flow control section reduces the flow as compared with a case where the temperature is higher than the threshold value.
According to this configuration, thermal resistance and fouling resistance can be improved.
An internal combustion engine comprising:
a coolant passage through which coolant flows;
a hole formation portion which forms a mounting hole for mounting an ignition plug; and
an ignition plug according to any one of application examples 1 to 4 and mounted in the mounting hole,
wherein the hole formation portion forms the mounting hole extending through the coolant passage, and
a portion of the metallic shell of the ignition plug is exposed to the interior of the coolant passage.
According to this configuration, thermal resistance can be improved.
An internal combustion engine system comprising:
an internal combustion engine according to application example 6, and
a control system according to application example 5 and adapted to control the internal combustion engine.
According to this configuration, thermal resistance and fouling resistance can be improved.
The technique disclosed in the present specification can be implemented in various forms; for example, an ignition plug, as internal combustion engine having the ignition plug, a control system for the internal combustion engine, an internal combustion engine system having the internal combustion engine and the control system, and a vehicle having the internal combustion engine system.
The ignition plug 100 has a tubular insulator 10 having a through hole 12 (may also be called an axial hole 12) extending along the axial line CL, a center electrode 20 held in the through hole 12 at the forward-end side, a metal terminal member 40 held in the through hole 12 at the rear-end side, a resistor 74 disposed within the through hole 12 between the center electrode 20 and the metal terminal member 40, a first seal 72 electrically connecting the resistor 74 and the center electrode 20, a second seal 76 electrically connecting the resistor 74 and the metal terminal member 40, a tubular metallic shell 50 fixed to the outer circumference of the insulator 10, and a ground electrode 30 whose one end is joined to a forward end surface 55 of the metallic shell 50 and whose other end faces the center electrode 20 with a gap g formed therebetween.
The insulator 10 has a large-diameter portion 14 having the largest outside diameter and formed at an approximately axial center. The insulator 10 has a rear-end-side trunk portion 13 formed on the rear-end side of the large-diameter portion 14. The insulator 10 has a forward-end-side trunk portion 15 formed on the forward-end side of the large-diameter portion 14 and having arm outside diameter smaller than that of the rear-end-side trunk portion 13. The insulator 10 has an outside-diameter-reducing portion 16 and a leg portion 19 formed on the forward-end side of the forward-end-side trunk portion 15 in this order toward the forward-end side. The outside diameter of the outside-diameter-reducing portion 16 gradually reduces in the forward direction Df. The insulator 10 has an inside-diameter-reducing portion 11 formed in the vicinity of the outside-diameter-reducing portion 16 (in the example of
The center electrode 20 is a rodlike member extending from the rear-end side toward the forward-end side. The center electrode 20 is disposed in the through hole 12 of the insulator 10 at a forward direction Df side end portion. The center electrode 20 has a head portion 24 having the largest outside diameter, a shaft portion 27 formed on the forward direction Df side of the head portion 24, and a first tip 29 joined (e.g., laser-welded) to the forward end of the shaft portion 27. The outside diameter of the head portion 24 is greater than the inside diameter of a portion of the insulator 10 located on the forward direction Df side of the inside-diameter-reducing portion 11. The forward direction Df side surface of the head portion 24 is supported by the inside-diameter-reducing portion 11 of the insulator 10. The shaft portion 27 extends in the forward direction Df in parallel with the axial line CL. The shaft portion 27 has an outer layer 21 and a core 22 disposed on the inner-circumference side of the outer layer 21. The outer layer 21 is formed of, for example, an alloy which contains nickel as a main component. The main component means a component having the highest content (weight %). The core 22 is formed of a material (e.g., an alloy which contains copper as a main component) higher in thermal conductivity than the outer layer 21. The first tip 29 is formed by use of a material (e.g., a noble metal such as iridium (Ir), platinum (Pt), or the like, tungsten (W), or an alloy which contains at least one of these metals) superior to the shaft portion 27 in durability against discharge. A forward-end-side portion including the first tip 29 of the center electrode 20 protrudes from the axial hole 12 of the insulator 10 toward the forward direction Df side. At least one of the core 22 and the first tip 29 may be eliminated. Also, the entire center electrode 20 may be disposed within the axial hole 12.
A forward direction Df side portion of the metal terminal member 40 is inserted into the rear-end side of the through hole 12 of the insulator 10. The metal terminal member 40 is a rodlike member extending in parallel with the axial line CL. The metal terminal member 40 is formed by use of an electrically conductive material (e.g., a metal which contains iron as a main component). The metal terminal member 40 has a cap attachment portion 49, a collar portion 48, and a shaft portion 41 disposed sequentially in the forward direction Df. The cap attachment portion 49 is disposed outside the axial hole 12 on the rear-end side of the insulator 10. A plug cap connected to a high-voltage cable (not shown) is fitted to the cap attachment portion 49 for application of high voltage for generation of spark discharge. The cap attachment portion 49 is an example of a terminal portion to which a high-voltage cable is connected. The shaft portion 41 is inserted into a rearward direction Dfr portion of the axial hole 12 of the insulator 10. The forward direction Df side surface of the collar portion 48 is in contact with the rearward direction Dfr side end, or a rear end 10e, of the insulator 10.
The resistor 74 is disposed within the axial hole 12 of the insulator 10 between the metal terminal member 40 and the center electrode 20 for restraining electrical noise. The resistor 74 is formed by use of an electrically conductive material (e.g., a mixture of glass, carbon particles, and ceramic particles). The first seal 72 is disposed between the resistor 74 and the center electrode 20, and the second seal 76 is disposed between the resistor 74 and the metal terminal member 40. These seals 72 and 76 are formed by use of an electrically conductive material (e.g., a mixture of metal particles and glass similar to that contained in the material of the resistor 74). The center electrode 20 is electrically connected to the metal terminal member 40 by means of the first seal 72, the resistor 74, and the second seal 76. Hereinafter, the first seal 72, the resistor 74, and the second seal 76 which electrically connect the metal terminal member 40 and the center electrode 20 within the axial hole 12 of the insulator 10 may also be collectively called a connection member 200.
In manufacture of the ignition plug 100, the center electrode 20 is inserted into the insulator 10 from a rearward direction Dfr side opening 10q of the insulator 10. The center electrode 20 is supported by the inside-diameter-reducing portion 11 of the insulator 10 to thereby be disposed at a predetermined position within the through hole 12. Next, material powders of the first seal 72, the resistor 74, and the second seal 76 are charged, and the charged material powders are compacted, in the order of the members 72, 74, and 76. The material powders are charged into the through hole 12 from the opening 10q. Next, the insulator 10 is heated to a predetermined temperature higher than the softening temperature of a glass component contained in the material powders of the members 72, 74, and 76; then, in a state in which the insulator 10 is heated to the predetermined temperature, the shaft portion 41 of the metal terminal member 40 is inserted into the through hole 12. As a result, the material powders of the members 72, 74, and 76 are compressed and sintered, thereby forming the members 72, 74, and 76. Further, the metal terminal member 40 is fixed to the insulator 10.
The metallic shell 50 is a tubular member having a through hole 59 extending along the axial line CL. The insulator 10 is inserted into the through hole 59 of the metallic shell 50, and the metallic shell 50 is fixed to the outer circumference of the insulator 10. The metallic shell 50 is formed by use of an electrically conductive material (e.g., a metal such as low-carbon steel or the like). A forward direction Df side portion of the insulator 10 protrudes outward from the through hole 59. Also, a rearward direction Dfr side portion of the insulator 10 protrudes outward from the through hole 59.
The metallic shell 50 has a tool engagement portion 51 and a trunk portion 52. The tool engagement portion 51 allows an ignition plug wrench (not shown) to be fitted thereto. The trunk portion 52 includes the forward end surface 55 of the metallic shell 50. The trunk portion 52 has a threaded portion 57 formed on the outer circumferential surface thereof and adapted to be threadingly engaged with a mounting hole of an internal combustion engine (e.g., a gasoline engine). The threaded portion 57 is an external thread and has a spiral thread ridge (not illustrated).
The metallic shell 50 has a flange-like collar portion 54 formed between the tool engagement, portion 51 and the trunk portion 52 and protruding radially outward. An annular gasket 90 is disposed between the collar portion 54 and the threaded portion 57 of the trunk portion 52. The gasket 90 is formed by, for example, folding a plate-like member of metal, and, when the ignition plug 100 is mounted to an engine, the gasket 90 is crushed and deformed. As a result of deformation of the gasket 90, a gap between the ignition plug 100 (specifically, the forward direction Df side surface of the collar portion 54) and the engine is sealed, whereby outward leakage of combustion gas is restrained.
The trunk portion 52 of the metallic shell 50 has an inside-diameter-reducing portion 56 whose inside diameter gradually reduces toward the forward-end side. A forward-end-side packing 8 is held between the inside-diameter-reducing portion 56 of the metallic shell 50 and the outside-diameter-reducing portion 16 of the insulator 10. In the present embodiment, the forward-end-side packing 8 is, for example, a plate-like ring made of iron (other materials (e.g., metal materials such as copper, etc.) can be employed).
The metallic shell 50 has a thin-walled crimp portion 53 formed on the rear-end side of the tool engagement portion 51. Also, the metallic shell 50 has a thin buckled portion 58 between the flange-like collar portion 54 and the tool engagement portion 51. Annular ring members 61 and 62 are inserted between an inner circumferential surface of the metallic shell 50 extending from the tool engagement portion 51 to the crimp portion 53 and an outer circumferential surface of the rear-end-side trunk portion 13 of the insulator 10. Further, powder of talc 70 is charged between these ring members 61 and 62. In the manufacturing process of the ignition plug 100, when the crimp portion 53 is formed through radially inward bending for crimping, associated application of compressive force forms the buckled portion 58 through radially outward deformation (buckling); as a result, the metallic shell 50 and the insulator 10 are fixed together. In this crimping step, the talc 70 is compressed, thereby enhancing airtightness between the metallic shell 50 and the insulator 10. The packing 8 is pressed between the outside-diameter-reducing portion 16 of the insulator 10 and the inside-diameter-reducing portion 56 of the metallic shell 50, thereby providing a seal between the metallic shell 50 and the insulator 10.
The ground electrode 30 has a rodlike body portion 37 and a second tip 39 attached to a distal end portion 34 of the body portion 37. One end portion 33 (also called a proximal end portion 33) of the body portion 37 is joined to the forward end surface 55 of the metallic shell 50 (for example, resistance welding). The body portion 37 extends in the forward-end direction Df from the proximal end portion 33 joined to the metallic shell 50, is bent toward the center axis CL, and reaches the distal end portion 34. The second tip 39 is fixed (e.g., laser-welded) to a rearward direction Dfr side portion of the distal end portion 34. The second tip 39 of the ground electrode 30 and the first tip 29 of the electrode 20 form the gap g therebetween. The second tip 39 is formed by use of a material (e.g., a noble metal such as iridium (Ir), platinum (Pt), or the like, tungsten (W), or an alloy which contains at least one of these metals) superior to the body portion 37 in durability against discharge. The body portion 37 has an outer layer 31 and an inner layer 32 disposed on the inner-circumference side of the outer layer 31. The outer layer 31 is formed of a material (e.g., an alloy which contains nickel) superior to the inner layer 32 in oxidization resistance. The inner layer 32 is formed of a material (e.g., pure copper, a copper alloy, or the like) higher in thermal conductivity than the outer layer 31. At least one of the inner layer 32 and the second tip 39 may be eliminated.
Metallic-shell contact area Ss is the surface area of the outer circumferential surface of a portion of the metallic shell 50 ranging from the rear end 57r of the threaded portion 57 to the forward end. 57f of the threaded portion 57 (in
The exposed portion 50x extends from a first position P1 on the inner circumferential surface of the metallic shell 50 to a second position P2 on the outer circumferential surface of the metallic shell 50 by way of the forward end surface 55 of the metallic shell 50.
The exposed portion 10x extends from a third position P3 on the outer circumferential surface of the insulator 10 to a fourth position P4 on the inner circumferential surface of the insulator 10 by way of a forward end 17 of the insulator 10.
In the example of
First area ratio R1 (=Ss/(Sa+Sb)) appearing in the table of
As shown in
At a first area ratio R1 of 2.6, 2.7, 3.3, and 4.1, an advance angle of occurrence AG of 56 degrees or greater was realized. A preferred range (a range of a lower limit to an upper limit) of first area ratio R1 may be determined by use of the four values. Specifically, any one of the above-mentioned four values may be employed as the lower limit of the preferred range of first area ratio R1. For example, first area ratio R1 may be 2.6 or greater. Of these values, any one equal to or greater than the lower limit may be employed as the upper limit of the preferred range of first area ratio R1. For example, first area ratio R1 may be 4.1 or less. Since the greater the first area ratio R1, the greater the extent to which an increase in temperature of the ignition plug 100 is restrained, the greater the first area ratio R1, the greater the restraint of occurrence of defects (e.g., preignition) caused by an increase in temperature of the ignition plug 100. Therefore, first area ratio R1 may be greater than 4.1 which is the greatest one of the above-mentioned four values. In a low-temperature environment, in order to accelerate an increase in temperature of the ignition plug 100, it is preferred that first area ratio R1 be small. For example, a first area ratio R1 of 5.2 or less is preferred.
Since thermal resistance evaluated by the present evaluation test is related to ease of cooling of the ignition plug, conceivably, influence of first area ratio R1 on thermal resistance is large, whereas influence of other parameters (e.g., Dn, Ls, Ss, Sa, Sb, etc.) is relatively small. Therefore, the above-mentioned preferred range of first area ratio R1 is conceivably applicable to ignition plugs having various values of parameters (e.g., Dn, Ls, Ss, Sa, Sb, etc.).
Volume difference Dv (=Vv−Vc) appearing in the table of
The forward-end-side member portion 300m (
The test operation consisting of the first operation and the second operation was repeated. Every time one-cycle test operation was completed, the ignition plug samples were measured for insulation resistance between the center electrode 20 and the metallic shell 50. Since electric resistance between the metal terminal member 40 and the center electrode 20 is sufficiently small as compared with insulation resistance, a measured insulation resistance between the metal terminal member 40 and the metallic shell 50 was employed as insulation resistance between the center electrode 20 and the metallic shell 50. The number of cycles Nc at the stage in which the average insulation resistance of four samples mounted in the engine became 10 MΩ or less was obtained for individual samples Nos. 8 to 13. As a result of driving of the internal combustion engine, carbon can adhere to the surface of the insulator 10 (called fouling). In the case where such fouling is apt to advance, insulation resistance is apt to drop, and the number of cycles Nc is small. A large number of cycles Nc indicates that fouling of the ignition plug 100 is restrained. Rating A in
As shown in
The reason why the case of small volume difference Dv exhibits good fouling resistance is conceivably as follows. As mentioned above, since in the case of small volume difference Dv, the forward-end-side member portion 300m (
A volume difference Dv of 1,882, 1,938, and 1,960 (mm3) exhibited numbers of cycles Nc evaluated as A. A preferred range (a range of a lower limit to an upper limit) of volume difference Dv may be determined by use of these three values. Specifically, any one of the above-mentioned three values may be employed as the upper limit of the preferred range of volume difference Dv. For example, volume difference Dv may be equal to or less than 1,960 mm3. Of these values, any one equal to or less than the upper limit may be employed as the lower limit of the preferred range of volume difference Dv. For example, volume difference Dv may be 1,882 mm3 or greater. Since the smaller the volume difference Dv, the more the acceleration of temperature rise of the insulator 10, the smaller the volume difference Dv, the greater the restraint of occurrence of defects (e.g., fouling by carbon) caused by low temperature of the ignition plug 100. Therefore, volume difference Dv may be smaller than a smallest volume of 1,882 mm3 of the above-mentioned three values. In order to improve durability of a portion of the ignition plug 100 corresponding to the forward-end-side member portion 300m, it is preferred that volume difference Dv of the forward-end-side member portion 300m be large. For example, a volume difference Dv of 1,000 mm3 or greater is preferred.
As shown in
Since fouling resistance evaluated by the present evaluation test is related to ease of temperature rise of the ignition plug (particularly, the forward-end-side member portion 300m), conceivably, influence of volume difference Dv on fouling resistance is large, whereas influence of other parameters (e.g., Dn, Ls, Ss, Vv, Sa, Sb, Vc, and R1) is relatively small. Therefore, the above-mentioned preferred range of volume difference Dv is conceivably applicable to ignition plugs having various values of parameters (e.g., Dn, Ls, Ss, Vv, Sa, Sb, Vc, and R1). However, volume difference Dv may fall outside the above-mentioned preferred range; for example, volume difference Dv may be greater than 2,000 mm3.
In the course of driving of the internal combustion engine, within a combustion chamber, gas (e.g., combustion gas) flows, and a pressure wave propagates via gas. As a result of contact with the insulator 10, the flowing gas and the pressure wave may apply force to the insulator 10. For example, the gas and the pressure wave may move in a direction intersecting with the axial line CL in the vicinity of the forward end portion 10f of the insulator 10. As a result of contact with the forward end portion 10f of the insulator 10, such gas and the pressure wave can apply force to the insulator 10 in a direction intersecting with the axial line CL. The greater the projected area Sd, the greater the portion of the insulator 10 which receives force from the gas and the pressure wave. Therefore, the greater the projected area Sd, the stronger the force which the insulator 10 receives. The shape of the illustrated forward end portion 10f is the same as the shape of the projected forward end portion 10f. Therefore, projected area Sd can be calculated by use of such an exterior view.
Second area ratio R2 appearing in the table of
The outline of the durability evaluation test is as follows. The samples are mounted to a direct-injection turbocharged engine of 1.6 L displacement, and the engine is operated at a rotational speed of 2,000 rpm and a boost pressure of 100 kPa with full throttle opening. Although there are various opinions, there may arise abnormal combustion such that under conditions of such low load and high boost pressure, compounds generated as a result of combustion of oil drops and additives of lubrication oil collected in a piston rod clevis portion self-ignite. As a result of such abnormal combustion, an intensive pressure wave has been propagated within a combustion chamber in some cases. Abnormal combustion which induces such a pressure wave is also called super-knock. In the present evaluation test, a pressure sensor was used to measure pressure within a combustion chamber, and in the event of excessive pressure over a threshold value higher than a regular combustion pressure, the event was judged as the occurrence of abnormal combustion (specifically, super-knock). At the stage in which the number of occurrences of abnormal combustion reached 100, the engine was stopped; the samples were removed from the engine; and then the insulators 10 of the samples were inspected for abnormality. Rating A appearing in the test results of
As shown in
Rating A was realized at a second area ratio R2 of 0.29, 0.35, and 0.46. A preferred range (a range of a lower limit to an upper limit) of second area ratio R2 may be determined by use of these three values. Specifically, any one of the above-mentioned three values may be employed as the upper limit of the preferred range of second area ratio R2. For example, second area ratio R2 may be equal to or less than 0.46. Of these values, any one equal to or smaller than the upper limit may be employed as the lower limit of the preferred range of second area ratio R2. For example, second area ratio R2 may be 0.29 or greater. Conceivably, the smaller the second area ratio R2, the greater the improvement of durability of the insulator 10. Therefore, second area ratio R2 may be smaller than 0.29, which is the smallest value of the above-mentioned three values. The entire forward end portion of the insulator 10 may be disposed on the rearward direction Dfr side of the forward end (herein, the forward end surface 55) of the metallic shell 50. That is, the entire forward end portion of the insulator 10 may be disposed within the through hole 59 of the metallic shell 50. In this case, projected area Sd is zero, and second area ratio R2 is zero. In this manner, projected area Sd may assume various values equal to or greater than zero. Also, second area ratio R2 may assume various values equal to or greater than zero.
Since durability of the insulator 10 evaluated by the present evaluation test is mechanical durability, conceivably, influence of second area ratio R2 on durability is large, whereas influence of other parameters (e.g., Ss, Vv, Sa, Sb, Vc, Sd, and Se) is relatively small. Therefore, the above-mentioned preferred range of second area ratio R2 is conceivably applicable to ignition plugs having various values of parameters (e.g., Ss, Vv, Sa, Sb, Vc, Sd, and Se).
In the course of driving of an internal combustion engine, the insulator 10 (
The table of
As shown in
Rating A was realized at a distance F of 5.0, 7.3, and 10.0 (mm). A preferred range (a range of a lower limit to an upper limit) of distance F may be determined by use of these three values. Specifically, any one of the above-mentioned three values may be employed as the lower limit of the preferred range of distance F. For example, distance F may be 5.0 mm or more. Of these values, any one equal to or greater than the lower limit may be employed as the upper limit of the preferred range of distance F. For example, distance F may be 10.0 mm or less. Since the longer the distance F, the greater the extent to which a temperature change of a portion of the insulator 10 in the vicinity of third position P3 is restrained, the longer the distance F, the greater the restraint of breakage of the insulator 10. Therefore, distance F may be longer than 10.0 mm which is the greatest one of the above-mentioned three values.
In the present thermal shock test, the temperature of the metallic shell 50 is maintained at 100 degrees C. or less through cooling by the water-cooling jacket. Meanwhile, in ordinary operation of an internal combustion engine, the metallic shell 50 can be maintained at a temperature higher than 100 degrees C. The present thermal shock test can be said to be conducted under severe conditions such that a temperature change is apt to become great as compared with ordinary driving conditions of the internal combustion engine. Therefore, in mounting the ignition plug 100 on an ordinary internal combustion engine, distance F may be less than 5.0 mm.
As shown in
Since durability of the insulator 10 evaluated by the present evaluation test is related to a temperature change of a portion of the insulator 10 in the vicinity of third position P3, conceivably, influence of distance F on durability is large, whereas influence of other parameters (e.g., Dn, Ls, Ss, Vv, Sa, Sb, Vc, R1, Dv, Sd, Se, R2, etc.) is relatively small. Therefore, the above-mentioned preferred range of distance F is conceivably applicable to ignition plugs having various values of parameters (e.g., Dn, Ls, Ss, Vv, Sa, Sb, Vc, R1, Dv, Sd, Se, R2, etc.).
The cylinder head 610 is disposed on the cylinder block 620. The cylinder head 610 has an intake passage 651 and an exhaust passage 652 provided therein. The cylinder head 610 has an intake port 631 communicating with the intake passage 651, an exhaust port 632 communicating with the exhaust passage 652, and the mounting hole 680 disposed between the intake port 631 and the exhaust port 632, in a region which faces the cylinder 639. The ignition plug 100 is mounted in the mounting hole 680. The drawing shows the schematic exterior view of the ignition plug 100. A cylinder 639 side portion of the hole formation portion 688 forming the mounting hole 680 has a threaded portion 682. The threaded portion 682 is an internal thread and has a spiral thread ridge (not shown). The threaded portion 57 of the ignition plug 100 is screwed into the threaded portion 682 of the hole formation portion 688.
The cylinder head 610 further has an intake valve 641 for opening/closing the intake port 631, a first drive member 643 for driving the intake valve 641, an exhaust valve 642 for opening/closing the exhaust port 632, and a second drive member 644 for driving the exhaust valve 642. The first drive member 643 includes, for example, a coil spring for urging the intake valve 641 in a closing direction, and a cam for moving the intake valve 641 in an opening direction. The second drive member 644 includes, for example, a coil spring for urging the exhaust valve 642 in a closing direction, and a cam for moving the exhaust valve 642 in an opening direction.
The combustion chamber 630 is a space of the cylinder block 620 surrounded by the wall of the cylinder 639, the piston 691, a portion of the cylinder head 610 facing the cylinder 639, the intake valve 641, the exhaust valve 642, and the ignition plug 100.
The internal combustion engine 600 has channels 661 to 664, 671, and 672 through which cooling water flows (such channels are also collectively called a water jacket). Hereinafter, the channels 661 to 664 formed in the cylinder head 610 are also called the head channels 661 to 664, and the channels 671 and 672 formed in the cylinder block 620 are also called the block channels 671 and 672.
The first head channel 661 is provided in the cylinder head 610 between the intake valve 641 and the threaded portion 682 of the mounting hole 680. The second head channel 662 is provided in the cylinder head 610 between the exhaust valve 642 and the threaded portion 682 of the mounting hole 680. These head channels 661 and 662 are provided between the threaded portion 682 of the mounting hole 680 and the valves 641 and 642. Therefore, cooling water flowing through the head channels 661 and 662 can appropriately cool the ignition plug 100 mounted in the mounting hole 680. The third head channel 663 and the fourth head channel 664 are provided in the cylinder head 610 at other positions.
The first block channel 671 and the second block channel 672 are disposed in such a manner as to have the combustion chamber 630 located therebetween. In the example of
The first channel 781 is connected to the downstream side of the radiator 700. The first channel 781 branches into the second channel 782 and the third channel 783. The second channel 782 is connected to the upstream side of a head channel 660 of the internal combustion engine 600, and the third channel 783 is connected to the upstream side of a block channel 670 of the internal combustion engine 600. The head channel 660 represents, as a single channel, a plurality of channels provided in the cylinder head 610 (
The pump 730 is provided in the first channel 781. The pump 730 supplies cooling water cooled by the radiator 700 to the channels 660 and 670 of the internal combustion engine 600 through the channels 781, 782, and 783 and circulates the cooling water output from the channels 660 and 670 of the internal combustion engine 600 to the radiator 700 through the channels 784, 785, and 786. The pump 730 is driven by driving force of the internal combustion engine 600. Alternatively, the pump 730 may include an electric motor as a driving unit.
The temperature sensor 750 is fixed to the internal combustion engine 600 for measuring the temperature of the internal combustion engine 600. The temperature sensor 750 may be fixed to the internal combustion engine 600 at any position where the temperature of the internal combustion engine 600 can be measured. For example, the temperature sensor 750 is fixed to the cylinder head 610. Alternatively, the temperature sensor 750 may be fixed to the cylinder block 620. Also, the temperature sensor 750 may measure the temperature of cooling water flowing through the head channel 660 or the block channel 670. Since the temperature of cooling water correlates with the temperature of the internal combustion engine 600, the temperature sensor 750 which measures the temperature of cooling water can be said to indirectly measure the temperature of the internal combustion engine 600.
The valve 740 is provided in the second channel 782. The valve 740 can control flow per unit time of cooling water flowing through the head channel 660 of the internal combustion engine 600. The smaller the opening of the valve 740, the smaller the flow per unit time of cooling water flowing through the head channel 660 (e.g., the channels 661 and 662 for cooling the ignition plug 100 (
The control unit 500 controls the valve 740 in response to a signal from the temperature sensor 750. In the present embodiment, the control unit 500 includes a processor 510 such as CPU, a volatile storage device 520 such as RAM, a nonvolatile storage device 530 such as ROM, and an interface 540 for allowing connection of external devices. A program 535 is stored beforehand in the nonvolatile storage device 530. The valve 740 and the temperature sensor 750 are connected to the interface 540. The processor 510 operates according to the program 535 to thereby control the valve 740.
In the case of temperature T equal to or lower than a predetermined threshold value Tt between first temperature T1 and second temperature T2, opening Vo is small as compared with the case of temperature T higher than threshold value Tt. Specifically, flow per unit time of cooling water flowing through the head channels 661 and 662 (
The downstream side of the first radiator 710 and the upstream side of the head channel 660 are connected by the first channel 791, and the downstream side of the head channel 660 and the upstream side of the first radiator 710 are connected by the second channel 792. The first pump 731 and the valve 740 are provided in the first channel 791. The first pump 731 circulates cooling water between the first radiator 710 and the head channel 660. The valve 740 can control flow per unit time of cooling water flowing through the head channel 660.
The downstream side of the second radiator 720 and the upstream side of the block channel 670 are connected by the third channel 793, and the downstream side of the block channel 670 and the upstream side of the second radiator 720 are connected by the fourth channel 794. The second pump 732 is provided in the third channel 793. The second pump 732 circulates cooling water between the second radiator 720 and the block channel 670.
The pumps 731 and 732 are driven by driving force of the internal combustion engine 600. Alternatively, the pumps 731 and 732 may be driven by electric motors.
Similar to the embodiment of
The head channel 661a is provided in a region approximately identical to a region where the head channels 661 and 662 of
In the embodiment of
The drawing schematically shows the exterior view of the ignition plug 100a mounted in the mounting hole 680a. A metallic shell 50a has a first threaded portion 57d and a second threaded portion 57u. The first threaded portion 57d is screwed into the first threaded portion 682d of the mounting hole 680a, and the second threaded portion 57u is screwed into the second threaded portion 682u of the mounting hole 680a. The outer circumferential surface of a portion of the metallic shell 50a between the first threaded portion 57d and the second threaded portion 57u has a cylindrical shape having no threaded portion.
In this manner, in the embodiment of
(1) The ignition plug can employ various configurations other than the above-mentioned configuration. For example, the threaded portion of the metallic shell to be engaged with the thread ridge of the mounting hole of the internal combustion engine may be composed of the two threaded portions 57d and 57u as in the case of the metallic shell 50a of
Also, a discharge gap may be formed between the ground electrode and a side surface (a surface located away from the axial line CL in a direction perpendicular to the axial line CL) of the center electrode. The total number of discharge gaps may be two or more. A magnetic material may be disposed between the center electrode 20 and the metallic terminal member 40. The resistor 74 may be eliminated.
In any case, even in the case of use of thin ignition plugs having a nominal diameter Dn of 12 mm or less of the threaded portion of the metallic shell as in the case of samples Nos. 1 to 13 of
(2) The packing 8 (
(3) In the embodiments of
Regarding the configuration of the flow control section for controlling flow of channels for cooling the ignition plug 100, in place of the configuration including the control unit 500 and the valve 740, any configuration capable of controlling flow can be employed. For example, in the embodiment of
Generally, regarding the flow control section, in the case of temperature T equal to or lower than threshold value Tt, there can be employed any configuration capable of reducing flow per unit time of cooling water flowing through channels (e.g., the head channels 661 and 662 of
(4) Regarding the configuration of a coolant passage for cooling the ignition plug, any configuration capable of cooling the ignition plug can be employed in place of the configuration of the channels 661 and 662 of
(5) Regarding the configuration of the ignition plug and the configuration of the internal combustion engine, in place of the configurations shown in
Regarding the configuration of the internal combustion engine system, in place of the configurations of the systems 1000a and 1000B shown in
(6) In the above-mentioned embodiments, a portion of the configuration realized by hardware may be replaced with software; in contrast, a portion or the entirety of the configuration realized by software may be replaced with hardware. For example, the functions of controlling opening Vo of the valve 740 by the control unit 500 shown in
In the case where the functions of the present invention are implemented partially or entirely by a computer program, the program can be provided while being stored in a computer readable recording medium (e.g., a nontemporary recording medium). The program can be used while being stored in the provided recording medium or a different recording medium (a computer readable recording medium). The “computer readable recording medium” is not limited to portable recording media such as memory cards and CD-ROMs, but includes internal storage devices of computers such as various ROMs, and external storage devices to be connected to computers, such as hard disk drives.
The present invention has been described with reference to the above embodiments and modified embodiments. However, the embodiments and modified embodiments are meant to help understand the invention, but are not meant to limit the invention. The present invention may be modified or improved without departing from the gist and the scope of the invention and encompasses equivalents of such modifications and improvements.
The present invention can be favorably applied to ignition plugs.
8: forward-end-side packing; 10: insulator; 10e: rear end; 10f: forward end portion; 10i: inner circumferential surface; 10o: outer circumferential surface; 10q: opening; 10x: exposed portion; 10z: section; 11: inside-diameter-reducing portion; 12: through hole (axial hole); 13: rear-end-side trunk portion; 14: large-diameter portion; 15: forward-end-side trunk portion; 16: outside-diameter-reducing portion; 17: forward end; 19: leg portion; 20: center electrode; 20o: outer circumferential surface; 21: outer layer; 22: core; 24: head portion; 26: outside-diameter-reducing portion; 27: shaft portion; 29: first tip; 30: ground electrode; 31: outer layer; 32: inner layer; 33: proximal end portion; 34: distal end portion; 37: body portion; 39: second tip; 40: metal terminal member; 41: shaft portion; 48: collar portion; 49: cap attachment portion; 50, 50a: metallic shell; 50f: forward-end-side portion; 50i: inner circumferential surface; 50x: exposed portion; 51: tool engagement portion; 52: trunk portion; 53: crimp portion; 54: collar portion; 55: forward end surface; 56: inside-diameter-reducing portion; 57: threaded portion; 57d: first threaded portion; 57f: forward end; 57r: rear end; 57u: second threaded portion; 57fd: forward end; 57ru: rear end; 58: buckled portion; 59: through hole; 61: ring member; 70: talc; 72: first seal; 74: resistor; 76: second seal; 90: gasket; 100, 100a: ignition plug; 200: connection member; 300: imaginary forward-end-side portion; 300f: forward-end-side space portion; 300m: forward-end-side member portion; 500: control unit; 510: processor; 520: volatile storage device; 530: nonvolatile storage device; 535: program; 540: interface; 600, 600a: internal combustion engine; 610: cylinder head; 620: cylinder block; 630: combustion chamber; 631: intake port; 632: exhaust port; 639: cylinder; 641: intake valve; 642: exhaust valve; 643: first drive member; 644: second drive member; 651: intake passage; 652: exhaust passage; 660: head channel; 661a: head channel; 661: first head channel; 662: second head channel; 663: third head channel; 664: fourth head channel; 670: block channel; 671: first block channel; 672: second block channel; 680, 680a: mounting hole; 682: threaded portion; 682d: first threaded portion; 682u: second threaded portion; 688, 688a: hole formation portion; 691: piston; 692: connecting rod; 700: radiator; 710: first radiator; 720: second radiator; 730: pump; 731: first pump; 732: second pump; 740: valve; 750: temperature sensor; 781: first channel; 782: second channel; 783: third channel; 784: fourth channel; 785: fifth channel; 786: sixth channel; 791: first channel; 792: second channel; 793: third channel; 794: fourth channel; 900A, 900B: control system; 910A: flow control section; 1000A, 1000B: internal combustion engine system; g: gap; CL: center axis (CL); Df: forward-end direction (forward direction); and Dfr: rear-end direction (rearward direction).
| Number | Date | Country | Kind |
|---|---|---|---|
| JP2016-153660 | Aug 2016 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2017/010226 | 3/14/2017 | WO | 00 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2018/025440 | 2/8/2018 | WO | A |
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| 20190165548 A1 | May 2019 | US |
