EP2020715A2 - Multipoint ignition device - Google Patents
Multipoint ignition device Download PDFInfo
- Publication number
- EP2020715A2 EP2020715A2 EP07021928A EP07021928A EP2020715A2 EP 2020715 A2 EP2020715 A2 EP 2020715A2 EP 07021928 A EP07021928 A EP 07021928A EP 07021928 A EP07021928 A EP 07021928A EP 2020715 A2 EP2020715 A2 EP 2020715A2
- Authority
- EP
- European Patent Office
- Prior art keywords
- intermediate member
- temperature
- electrode pair
- ignition device
- electrode pairs
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- 238000004140 cleaning Methods 0.000 claims abstract description 7
- 238000002485 combustion reaction Methods 0.000 claims description 18
- 239000000463 material Substances 0.000 claims description 11
- 238000000034 method Methods 0.000 description 9
- 230000005855 radiation Effects 0.000 description 6
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 4
- 239000007789 gas Substances 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- 229910052799 carbon Inorganic materials 0.000 description 3
- 230000001747 exhibiting effect Effects 0.000 description 3
- 239000000446 fuel Substances 0.000 description 3
- 239000000567 combustion gas Substances 0.000 description 2
- 239000000498 cooling water Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 239000004917 carbon fiber Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 239000003365 glass fiber Substances 0.000 description 1
- 239000012774 insulation material Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 238000011144 upstream manufacturing Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
- H01T13/00—Sparking plugs
- H01T13/46—Sparking plugs having two or more spark gaps
- H01T13/462—Sparking plugs having two or more spark gaps in series connection
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
- H01T13/00—Sparking plugs
- H01T13/02—Details
- H01T13/14—Means for self-cleaning
Definitions
- This invention relates to a multipoint ignition device in which a plurality of ignition gaps are disposed in a single combustion chamber.
- JP2-123281A and JP1-193080A disclose a multipoint ignition device in which a plurality of electrode pairs constituting ignition gaps are disposed around a cylinder opening portion such that an air-fuel mixture in a combustion chamber is ignited from the plurality of ignition gaps.
- the temperature of the electrode pair When the temperature of the electrode pair is lower than a self-cleaning temperature (between 450°C and 500°C), carbon sticks to the electrode pair, and as a result, a secondary voltage leaks, causing pollution such that a spark can no longer fly from the electrode pair. Conversely, when the temperature of the electrode pair rises above 1000°C, the electrode pair itself becomes a heat source, and this leads to pre-ignition, whereby ignition occurs before the spark flies. Hence, the temperature of each electrode pair in this multipoint ignition device must be maintained within an appropriate range (between 450°C and 1000°C, and more preferably between 500°C and 850°C so as to leave a margin for error).
- all of the electrode pairs are set with an identical heat value, regardless of the fact that the amount of heat received by the electrode pairs from the wall surface of the combustion chamber and the combustion gas and the amount of heat lost to fresh air differ according to the position of the electrode pair.
- the temperature of certain electrode pairs falls below an appropriate temperature range, causing pollution, while the temperature of other electrode pairs rises above the appropriate temperature range, causing pre-ignition.
- This invention has been designed in consideration of the problems in the prior art, and it is an object thereof to prevent both electrode pair pollution and pre-ignition in a multipoint ignition device.
- respective heat values of a plurality of electrode pairs are set individually such that temperatures of all of the plurality of electrode pairs are kept within an appropriate temperature range in which a temperature no lower than a self-cleaning temperature is set as a lower limit temperature and a lower temperature than a pre-ignition temperature is set as an upper limit temperature.
- the temperatures of all of the electrode pairs can be kept within the appropriate temperature range, and as a result, pollution of the electrode pairs and the occurrence of pre-ignition can be prevented.
- FIG. 1 is a schematic constitutional diagram of an engine comprising a multipoint ignition device according to this invention.
- FIG. 2 is a schematic constitutional diagram of the multipoint ignition device.
- FIG. 3 is a view showing a heat value of each electrode pair.
- FIGs. 4 and 5 are views illustrating a method of adjusting the heat value of the electrode pair.
- the heat radiation property of an electrode pair is expressed as a "heat value”, similarly to a conventional spark plug. Accordingly, a good heat radiation property is referred to as a "high heat value”, and a poor heat radiation property is referred to as a "low heat value”.
- FIG. 1 shows the schematic constitution of an engine 1 comprising a multipoint ignition device 7 according to this invention.
- the engine 1 is a four-valve engine having two intake valves 3 and two exhaust valves 4 for a single combustion chamber 2.
- the intake valve 3 is mounted in a near-horizontal state (the valve stem is near-vertical), and the majority of fresh air that is introduced into the combustion chamber 2 through an intake port 5 via the intake valve 3 flows to the exhaust side along an upper surface of the combustion chamber 2.
- the multipoint ignition device 7 is formed integrally with a head gasket 8 of the engine 1.
- a plurality of electrode pairs P1 to P8 constituting ignition gaps G1 to G8 are disposed at substantially equal intervals around a cylinder opening portion 14 that opens onto an upper surface of the cylinder block 10.
- Each electrode pair P1 to P8 is constituted by a current-carrying electrode and an earth electrode that faces the current-carrying electrode via a minute gap.
- each electrode pair P1 to P8 is formed from a metal exhibiting high heat resistance, such as nickel or platinum.
- a plurality of openings are formed in the head gasket 8, and a central opening 13, which is the largest opening, has a substantially identical diameter to the cylinder opening portion 14 and is superposed on the cylinder opening portion 14.
- a plurality of openings 15 disposed around the central opening 13 serve as water holes connected to cooling water passages formed in the cylinder head 9 and cylinder block 10.
- An intermediate member 16 formed from a conductive material is connected to each of the electrode pairs P1 to P8 such that adjacent electrode pairs are connected by the intermediate member 16.
- the intermediate members 16 are formed from the same material as the electrode pairs P1 to P8, for example nickel, but may be formed from a different material, as will be described below.
- the intermediate members 16 are buried in and held by the head gasket 8, and thus the electrode pairs P1 to P8 are held on the head gasket 8.
- the intermediate members 16 function to connect the electrode pairs P1 to P8 electrically in series.
- discharge occurs first in the gap G 1 of the electrode pair P1 connected to the terminal 20, after which discharge occurs in the gap G2 of the electrode pair P2 adjacent thereto.
- Discharge then occurs in the manner of a chain reaction in sequence from the terminal 20 side until finally, discharge occurs in the gap G8 of the electrode pair P8 connected to an earth terminal 21.
- the respective heat values of the electrode pairs P1 to P8 must be adjusted to appropriate values so that the temperature of all of the electrode pairs P1 to P8 is kept within an appropriate temperature range, or preferably so that the temperature of all of the electrode pairs P1 to P8 is substantially equal to a predetermined temperature within the appropriate temperature range.
- a lower limit temperature of the appropriate temperature range is no lower than the self-cleaning temperature (for example, 450°C, or 500°C to allow a margin for error), and an upper limit temperature is less than a temperature at which pre-ignition occurs (for example, 1000°C, or 850°C to allow a margin for error).
- the respective heat values of the electrode pairs P1 to P8 are set individually according to the position of the electrode pair in the following manner.
- a basic heat value is set to become gradually higher toward the electrode pairs disposed on the exhaust side (exhaust port side) of the cylinder opening portion 14.
- the basic heat value is a parameter used when setting the heat value of the electrode pairs P1 to P8, which is set for each electrode pair in accordance with the temperature of the combustion chamber wall on which the electrode pairs P1 to P8 are disposed.
- the reason for setting the basic heat value higher on the exhaust side than on the intake side is that the temperature on the exhaust side of the combustion chamber wall is higher than the temperature on the intake side by 50°C or more due to heat transfer from the high-temperature exhaust valve 4 and the valve seat portion thereof, and this temperature difference leads to deterioration of the heat radiation property of the electrode pairs disposed near the exhaust side of the combustion chamber wall. It should be noted, however, that this depends on the operating conditions of the engine 1.
- the heat values of the electrode pairs are set at lower values than the basic heat values thereof.
- the term "on which fresh air impinges directly” means that the fresh air introduced into the combustion chamber 2 impinges on the electrode pair before colliding with the combustion chamber wall and piston crown.
- the reason for setting the heat value of the electrode pairs P3, P5 on which the fresh air impinges directly to be lower than the basic heat value is that these electrode pairs P3, P5 lose heat to the fresh air such that the temperature thereof falls.
- the temperature of the electrode pairs P3, P5 can be maintained at or above the self-cleaning temperature.
- the respective heat values of the electrode pairs P1, P2, P4, P6 to P8 on which the fresh air does not impinge directly are set at the basic heat values set as described above.
- the temperature of all of the electrode pairs P1 to P8 can be held within the appropriate temperature range, or more preferably at a predetermined temperature within the appropriate temperature range, and as a result, pollution of the electrode pairs P1 to P8 and the occurrence of pre-ignition can be prevented.
- the heat values of the electrode pairs P1 to P8 are set in consideration of only the position of the electrode pair and whether or not fresh air directly impinges thereon.
- other factors contributing to the heat radiation property of the electrode pairs P1 to P8, for example the amount of heat received from the combustion gas, the distance from the cooling water passages, and so on may also be taken into account.
- the engine 1 of this embodiment is constituted such that a gas flow is not generated in the combustion chamber 2.
- a gas flow a swirl flow or a tumble flow
- the basic heat value of the electrode pair positioned on the farthest upstream side of the gas flow should be reduced by a maximum amount, and the basic heat values of the other electrode pairs should be reduced by steadily smaller amounts in the direction of the gas flow.
- a contact area between the head gasket 8 and the intermediate member 16 is modified.
- Px a certain electrode pair
- at least one of a length L, a width W, and a thickness T (see FIG. 4 ) of the intermediate member 16 that is connected to the electrode pair Px should be modified to modify the contact area between the intermediate member 16 connected to the electrode pair Px and the head gasket 8.
- the amount of heat transferred from the electrode pair Px to the cylinder head 9 and cylinder block 10 through the intermediate member 16 and the head gasket 8 increases, and thus the heat value of the electrode pair Px can be increased.
- at least one of the length L, width W, and thickness T of the intermediate member 16 connected to the electrode pair Px may be reduced.
- the contact area between the intermediate member 16 connected to the electrode pair Px and the head gasket 8 can be increased (not shown).
- the heat radiation property of the electrode pair Px improves, and as a result, the heat value can be increased.
- one or more voids 8v may be formed between the head gasket 8 and the intermediate member 16 to reduce the contact area between the intermediate member 16 connected to the electrode pair Px and the head gasket 8. According to this constitution, heat is less likely to be transferred from the electrode pair to the cylinder head 9 and cylinder block 10 through the intermediate member 16 and the head gasket 8, and as a result, the heat value of the electrode pair Px can be reduced.
- a thermal insulation material may be filled into the voids 8v.
- voids may be formed between the head gasket 8 and the intermediate member 16 by providing irregularities on the intermediate member 16 side rather than the head gasket 8 side.
- the intermediate member 16 connected to the electrode pair Px is formed from a different material to the electrode pair Px.
- the intermediate member 16 is formed from a material exhibiting higher thermal conductivity than the material of the electrode pair Px, for example copper
- the amount of heat transferred from the electrode pair Px to the cylinder head 9 and cylinder block 10 through the intermediate member 16 and the head gasket 8 increases, and thus the heat value of the electrode pair Px can be increased.
- the intermediate member 16 connected to the electrode pair Px may be formed from a material exhibiting lower thermal conductivity than the material of the electrode pair Px, for example carbon or glass fiber coated in carbon.
- first and second methods described above are merely examples of heat value adjustment methods, and other methods may be used. Further, a plurality of heat value adjustment methods, including the first and second methods described above, may be implemented in combination.
Abstract
Description
- This invention relates to a multipoint ignition device in which a plurality of ignition gaps are disposed in a single combustion chamber.
-
JP2-123281A JP1-193080A - According to this device, in comparison with a conventional spark plug that performs ignition only from the center of the combustion chamber, combustion of the air-fuel mixture in the peripheral edge portions of the combustion chamber is promoted, enabling improvements in engine output and fuel economy.
- When the temperature of the electrode pair is lower than a self-cleaning temperature (between 450°C and 500°C), carbon sticks to the electrode pair, and as a result, a secondary voltage leaks, causing pollution such that a spark can no longer fly from the electrode pair. Conversely, when the temperature of the electrode pair rises above 1000°C, the electrode pair itself becomes a heat source, and this leads to pre-ignition, whereby ignition occurs before the spark flies. Hence, the temperature of each electrode pair in this multipoint ignition device must be maintained within an appropriate range (between 450°C and 1000°C, and more preferably between 500°C and 850°C so as to leave a margin for error).
- However, in the prior art described above, all of the electrode pairs are set with an identical heat value, regardless of the fact that the amount of heat received by the electrode pairs from the wall surface of the combustion chamber and the combustion gas and the amount of heat lost to fresh air differ according to the position of the electrode pair. Hence, the temperature of certain electrode pairs falls below an appropriate temperature range, causing pollution, while the temperature of other electrode pairs rises above the appropriate temperature range, causing pre-ignition.
- This invention has been designed in consideration of the problems in the prior art, and it is an object thereof to prevent both electrode pair pollution and pre-ignition in a multipoint ignition device.
- In a multipoint ignition device according to this invention, respective heat values of a plurality of electrode pairs are set individually such that temperatures of all of the plurality of electrode pairs are kept within an appropriate temperature range in which a temperature no lower than a self-cleaning temperature is set as a lower limit temperature and a lower temperature than a pre-ignition temperature is set as an upper limit temperature.
- According to this invention, the temperatures of all of the electrode pairs can be kept within the appropriate temperature range, and as a result, pollution of the electrode pairs and the occurrence of pre-ignition can be prevented.
-
FIG. 1 is a schematic constitutional diagram of an engine comprising a multipoint ignition device according to this invention. -
FIG. 2 is a schematic constitutional diagram of the multipoint ignition device. -
FIG. 3 is a view showing a heat value of each electrode pair. -
FIGs. 4 and 5 are views illustrating a method of adjusting the heat value of the electrode pair. - An embodiment of this invention will be described below with reference to the attached drawings. In the following description, the heat radiation property of an electrode pair is expressed as a "heat value", similarly to a conventional spark plug. Accordingly, a good heat radiation property is referred to as a "high heat value", and a poor heat radiation property is referred to as a "low heat value".
-
FIG. 1 shows the schematic constitution of anengine 1 comprising amultipoint ignition device 7 according to this invention. Theengine 1 is a four-valve engine having twointake valves 3 and twoexhaust valves 4 for asingle combustion chamber 2. In this example, theintake valve 3 is mounted in a near-horizontal state (the valve stem is near-vertical), and the majority of fresh air that is introduced into thecombustion chamber 2 through anintake port 5 via theintake valve 3 flows to the exhaust side along an upper surface of thecombustion chamber 2. - As shown in
FIG. 2 , themultipoint ignition device 7 is formed integrally with ahead gasket 8 of theengine 1. When themultipoint ignition device 7 is sandwiched between acylinder head 9 and acylinder block 10 of theengine 1, a plurality of electrode pairs P1 to P8 constituting ignition gaps G1 to G8 are disposed at substantially equal intervals around acylinder opening portion 14 that opens onto an upper surface of thecylinder block 10. Each electrode pair P1 to P8 is constituted by a current-carrying electrode and an earth electrode that faces the current-carrying electrode via a minute gap. Similarly to a pre-existing electrode of a spark plug of the engine, each electrode pair P1 to P8 is formed from a metal exhibiting high heat resistance, such as nickel or platinum. - A plurality of openings are formed in the
head gasket 8, and acentral opening 13, which is the largest opening, has a substantially identical diameter to thecylinder opening portion 14 and is superposed on thecylinder opening portion 14. A plurality ofopenings 15 disposed around thecentral opening 13 serve as water holes connected to cooling water passages formed in thecylinder head 9 andcylinder block 10. - An
intermediate member 16 formed from a conductive material is connected to each of the electrode pairs P1 to P8 such that adjacent electrode pairs are connected by theintermediate member 16. Theintermediate members 16 are formed from the same material as the electrode pairs P1 to P8, for example nickel, but may be formed from a different material, as will be described below. Theintermediate members 16 are buried in and held by thehead gasket 8, and thus the electrode pairs P1 to P8 are held on thehead gasket 8. - As well as functioning to hold the electrode pairs P1 to P8, the
intermediate members 16 function to connect the electrode pairs P1 to P8 electrically in series. Hence, when a high secondary voltage is applied to aterminal 20, discharge occurs first in thegap G 1 of the electrode pair P1 connected to theterminal 20, after which discharge occurs in the gap G2 of the electrode pair P2 adjacent thereto. Discharge then occurs in the manner of a chain reaction in sequence from theterminal 20 side until finally, discharge occurs in the gap G8 of the electrode pair P8 connected to anearth terminal 21. - In this
multipoint ignition device 7, similarly to a conventional spark plug, pollution occurs when the temperature of the electrode pairs P1 to P8 is lower than a self-cleaning temperature. Conversely, when the temperature rises excessively, pre-ignition occurs. Hence, the respective heat values of the electrode pairs P1 to P8 must be adjusted to appropriate values so that the temperature of all of the electrode pairs P1 to P8 is kept within an appropriate temperature range, or preferably so that the temperature of all of the electrode pairs P1 to P8 is substantially equal to a predetermined temperature within the appropriate temperature range. A lower limit temperature of the appropriate temperature range is no lower than the self-cleaning temperature (for example, 450°C, or 500°C to allow a margin for error), and an upper limit temperature is less than a temperature at which pre-ignition occurs (for example, 1000°C, or 850°C to allow a margin for error). - Hence, in the
multipoint ignition device 7 according to this invention, the respective heat values of the electrode pairs P1 to P8 are set individually according to the position of the electrode pair in the following manner. - First, as shown by a broken line in
FIG. 3 , a basic heat value is set to become gradually higher toward the electrode pairs disposed on the exhaust side (exhaust port side) of thecylinder opening portion 14. The basic heat value is a parameter used when setting the heat value of the electrode pairs P1 to P8, which is set for each electrode pair in accordance with the temperature of the combustion chamber wall on which the electrode pairs P1 to P8 are disposed. The reason for setting the basic heat value higher on the exhaust side than on the intake side is that the temperature on the exhaust side of the combustion chamber wall is higher than the temperature on the intake side by 50°C or more due to heat transfer from the high-temperature exhaust valve 4 and the valve seat portion thereof, and this temperature difference leads to deterioration of the heat radiation property of the electrode pairs disposed near the exhaust side of the combustion chamber wall. It should be noted, however, that this depends on the operating conditions of theengine 1. - Next, the heat values of the electrode pairs, from among the electrode pairs P1 to P8, on which fresh air introduced into the
combustion chamber 2 through theintake port 5 impinges directly, i.e. the electrode pairs P3 and P5 disposed on the line of extension of theintake port 5 in this embodiment, are set at lower values than the basic heat values thereof. The term "on which fresh air impinges directly" means that the fresh air introduced into thecombustion chamber 2 impinges on the electrode pair before colliding with the combustion chamber wall and piston crown. The reason for setting the heat value of the electrode pairs P3, P5 on which the fresh air impinges directly to be lower than the basic heat value is that these electrode pairs P3, P5 lose heat to the fresh air such that the temperature thereof falls. By setting the heat value lower than the basic heat value, the temperature of the electrode pairs P3, P5 can be maintained at or above the self-cleaning temperature. On the other hand, the respective heat values of the electrode pairs P1, P2, P4, P6 to P8 on which the fresh air does not impinge directly are set at the basic heat values set as described above. - By setting the respective heat values of the electrode pairs P1 to P8 individually in accordance with the positions thereof in this manner, the temperature of all of the electrode pairs P1 to P8 can be held within the appropriate temperature range, or more preferably at a predetermined temperature within the appropriate temperature range, and as a result, pollution of the electrode pairs P1 to P8 and the occurrence of pre-ignition can be prevented.
- Here, the heat values of the electrode pairs P1 to P8 are set in consideration of only the position of the electrode pair and whether or not fresh air directly impinges thereon. However, other factors contributing to the heat radiation property of the electrode pairs P1 to P8, for example the amount of heat received from the combustion gas, the distance from the cooling water passages, and so on may also be taken into account.
- Further, the
engine 1 of this embodiment is constituted such that a gas flow is not generated in thecombustion chamber 2. However, in an engine that generates a gas flow (a swirl flow or a tumble flow) in the combustion chamber, the basic heat value of the electrode pair positioned on the farthest upstream side of the gas flow should be reduced by a maximum amount, and the basic heat values of the other electrode pairs should be reduced by steadily smaller amounts in the direction of the gas flow. - Next, as specific method of adjusting the heat value of the electrode pairs P1 to P8 will be described.
- In a first method, a contact area between the
head gasket 8 and theintermediate member 16 is modified. When adjusting the heat value of a certain electrode pair (to be referred to hereafter as Px) from among the electrode pairs P1 to P8, at least one of a length L, a width W, and a thickness T (seeFIG. 4 ) of theintermediate member 16 that is connected to the electrode pair Px should be modified to modify the contact area between theintermediate member 16 connected to the electrode pair Px and thehead gasket 8. - For example, when at least one of the length L, width W, and thickness T of the
intermediate member 16 connected to the electrode pair Px is increased, the amount of heat transferred from the electrode pair Px to thecylinder head 9 andcylinder block 10 through theintermediate member 16 and thehead gasket 8 increases, and thus the heat value of the electrode pair Px can be increased. Conversely, to lower the heat value of the electrode pair Px, at least one of the length L, width W, and thickness T of theintermediate member 16 connected to the electrode pair Px may be reduced. - Alternatively, by forming an irregularity such as a groove or a projection on the surface of the
intermediate member 16 connected to the electrode pair Px or bending the surface of theintermediate member 16, the contact area between theintermediate member 16 connected to the electrode pair Px and thehead gasket 8 can be increased (not shown). Likewise with this constitution, the heat radiation property of the electrode pair Px improves, and as a result, the heat value can be increased. - Alternatively, as shown in
FIG. 5 , one ormore voids 8v may be formed between thehead gasket 8 and theintermediate member 16 to reduce the contact area between theintermediate member 16 connected to the electrode pair Px and thehead gasket 8. According to this constitution, heat is less likely to be transferred from the electrode pair to thecylinder head 9 andcylinder block 10 through theintermediate member 16 and thehead gasket 8, and as a result, the heat value of the electrode pair Px can be reduced. - To ensure the strength of the
multipoint ignition device 7, a thermal insulation material may be filled into thevoids 8v. Moreover, voids may be formed between thehead gasket 8 and theintermediate member 16 by providing irregularities on theintermediate member 16 side rather than thehead gasket 8 side. - In a second method, the
intermediate member 16 connected to the electrode pair Px is formed from a different material to the electrode pair Px. When theintermediate member 16 is formed from a material exhibiting higher thermal conductivity than the material of the electrode pair Px, for example copper, the amount of heat transferred from the electrode pair Px to thecylinder head 9 andcylinder block 10 through theintermediate member 16 and thehead gasket 8 increases, and thus the heat value of the electrode pair Px can be increased. Conversely, to lower the heat value of the electrode pair Px, theintermediate member 16 connected to the electrode pair Px may be formed from a material exhibiting lower thermal conductivity than the material of the electrode pair Px, for example carbon or glass fiber coated in carbon. - It should be noted that the first and second methods described above are merely examples of heat value adjustment methods, and other methods may be used. Further, a plurality of heat value adjustment methods, including the first and second methods described above, may be implemented in combination.
- An embodiment of this invention was described above, but this embodiment is merely an example of application of the invention, and the technical scope of the invention is not limited to the specific constitution described above.
Claims (9)
- A multipoint ignition device having a plurality of electrode pairs (P1-P8) constituting ignition gaps (G1-G8), the plurality of electrode pairs (P1-P8) being disposed around a cylinder opening portion of an engine,
wherein respective heat values of the plurality of electrode pairs (P1-P8) are set individually such that temperatures of all of the plurality of electrode pairs (P1-P8) are kept within an appropriate temperature range in which a temperature no lower than a self-cleaning temperature is set as a lower limit temperature and a lower temperature than a pre-ignition temperature is set as an upper limit temperature. - The multipoint ignition device as defined in Claim 1, wherein the respective heat values of the plurality of electrode pairs (P1-P8) are set individually such that the temperatures of all of the plurality of electrode pairs (P1-P8) are substantially equal to a predetermined temperature within the appropriate temperature range.
- The multipoint ignition device as defined in Claim 1 or Claim 2, wherein the heat value of an electrode pair disposed on an exhaust side of the cylinder opening portion is raised to keep the temperature of the electrode pair within the appropriate temperature range.
- The multipoint ignition device as defined in any one of Claim 1 to Claim 3, wherein the heat value of an electrode pair on which fresh air introduced into a combustion chamber (2) of the engine impinges directly is lowered to keep the temperature of the electrode pair within the appropriate temperature range.
- The multipoint ignition device as defined in any one of Claim 1 to Claim 4, comprising:an intermediate member (16) that electrically connects adjacent electrode pairs; andan interposed member (8) interposed between a cylinder head and a cylinder block of the engine, in which the intermediate member (16) is buried,wherein the heat value of an electrode pair connected to the intermediate member (16) is modified by modifying a contact area between the intermediate member (16) and the interposed member (8).
- The multipoint ignition device as defined in Claim 5, wherein the contact area between the intermediate member (16) and the interposed member (8) is modified by modifying at least one of a length, a width, and a thickness of the intermediate member (16).
- The multipoint ignition device as defined in Claim 5 or Claim 6, wherein the contact area between the intermediate member (16) and the interposed member (8) is modified by providing one or more voids (8v) between the intermediate member (16) and the interposed member (8).
- The multipoint ignition device as defined in any one of Claim 5 to Claim 7, wherein the heat value of the electrode pair connected to the intermediate member (16) is modified by making a material of the intermediate member (16) different to a material of the electrode pair.
- The multipoint ignition device as defined in any one of Claim 1 to Claim 4, comprising:an intermediate member (16) that electrically connects adjacent electrode pairs; andan interposed member (8) interposed between a cylinder head and a cylinder block of the engine, in which the intermediate member is buried,wherein the heat value of an electrode pair connected to the intermediate member (16) is modified by making a material of the intermediate member (16) different to a material of the electrode pair.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
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JP2007200420A JP4079989B1 (en) | 2007-08-01 | 2007-08-01 | Multi-point ignition device |
JP2007203842A JP4139848B1 (en) | 2007-08-06 | 2007-08-06 | Multi-point ignition device |
Publications (3)
Publication Number | Publication Date |
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EP2020715A2 true EP2020715A2 (en) | 2009-02-04 |
EP2020715A3 EP2020715A3 (en) | 2011-12-21 |
EP2020715B1 EP2020715B1 (en) | 2012-08-15 |
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Application Number | Title | Priority Date | Filing Date |
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EP20070021928 Active EP2020715B1 (en) | 2007-08-01 | 2007-11-12 | Multipoint ignition device |
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Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
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US4535735A (en) * | 1981-05-09 | 1985-08-20 | Nippon Soken, Inc. | Multi-gap spark ignition system |
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2007
- 2007-11-12 EP EP20070021928 patent/EP2020715B1/en active Active
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
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US4535735A (en) * | 1981-05-09 | 1985-08-20 | Nippon Soken, Inc. | Multi-gap spark ignition system |
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EP2020715A3 (en) | 2011-12-21 |
EP2020715B1 (en) | 2012-08-15 |
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