JP2012102719A - Glow ignition engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a glow ignition engine that is properly driven by inexpensive low-ignition point fuel.SOLUTION: A glow ignition engine 1 has: a cylinder 2; a piston 3; a glow plug 4; and an adapter 5. A combustion room 6 is formed of the cylinder 2 and the piston 3. Gasoline is supplied into this combustion room 6. The piston 3 is provided in the cylinder 2. The glow plug 4 is fixed on the cylinder 2 via the adapter 5. The adapter 5 projects the edge of the glow plug 4 which ignites the gasoline into the combustion room 6.

Description

  The present invention relates to a glow ignition engine that ignites fuel with a glow plug.

  Patent Document 1 discloses a glow engine that ignites fuel with a glow plug. Since the glow engine does not need to have an ignition device like a gasoline engine because of its structure, it has an advantage of being small and light, and is used as an engine of a radio control helicopter, for example. In the glow engine described in Patent Document 1, the glow plug is fixed by screwing a screw formed on the outer peripheral surface of the tip portion for igniting the fuel supplied into the combustion chamber into the screw hole of the cylinder. Yes. Here, the length of the tip portion in the axial direction of the glow plug (hereinafter referred to as reach) is standardized by several types of lengths. Then, when assembling the glow engine, a reach glow plug corresponding to the thickness of the cylinder is selected and fixed. Specifically, a reach glow plug in which the tip of the glow plug and the wall surface of the combustion chamber substantially coincide is selected. It is because heat loss can be reduced and combustion efficiency can be improved by reducing the combustion chamber surface area.

JP-A-9-53429

  By the way, the glow engine has a drawback in that it requires a running cost because it is necessary to use an expensive fuel called methanol, which is methanol as a main fuel. However, if cheap fuel such as gasoline, LP gas, or kerosene is used instead of glow fuel, there is a problem that misfire or abnormal combustion occurs, and the glow engine cannot be driven appropriately. The reason for this is that fuels such as gasoline, LP gas, and kerosene have lower ignition points than glow fuels and are easy to ignite (hereinafter referred to as low ignition point fuels). It was thought to be because it was earlier.

  An object of the present invention is to provide a glow ignition engine that can be appropriately driven even by an inexpensive low ignition point fuel.

  In order to solve this problem, the present invention provides a glow ignition engine including a cylinder, a piston, a glow plug, and an adapter. The piston is provided in the cylinder. The glow plug is supplied into a combustion chamber formed by a cylinder and a piston, and ignites a fuel whose ignition point is lower than that of the glow fuel at the tip. The adapter is interposed between the cylinder and the glow plug, thereby fixing the glow plug to the cylinder and causing the tip portion to protrude into the combustion chamber.

  Here, in the present invention, the adapter has a fixing portion that fixes the glow plug to the inside of the adapter, and has a cylindrical shape having a screw that penetrates into the combustion chamber and is screwed into a screw hole formed in the cylinder on the outer peripheral surface. It is preferable to be formed. At this time, the fixing portion preferably fixes the glow plug by screwing a screw formed on the outer peripheral surface of the glow plug with a screw formed on the inner peripheral surface of the adapter. Moreover, it is preferable that an adapter has a notch part formed in at least one part of the edge part by the side of a piston so that it may not interfere with a piston when it exists in a top dead center. Further, the adapter has a guide portion including an internal groove into which a booster for energizing the glow plug is connected by being connected to the electrode of the glow plug, and the guide portion is arranged along the depth of the self-groove. It is preferable to lead to Furthermore, the adapter is preferably formed of a material having a lower thermal conductivity than that of the cylinder.

  As a result of diligent research, the present inventor has found that the glow engine can be appropriately driven with low ignition point fuel by continuously energizing the glow plug and maintaining a red hot state. And, from this, unlike the conventional recognition, the reason why the glow engine cannot be driven properly in a normal state where the glow plug is not energized except at the time of starting is the timing at which the low ignition point fuel is ignited. I found out that it was later than the appropriate timing. Further, the present inventor has found that the timing for performing ignition to the low ignition point fuel can be advanced by projecting the glow plug into the combustion chamber.

  According to the present invention, since the adapter projects the tip portion for igniting the fuel into the combustion chamber, the timing for igniting the fuel can be made earlier than that of the conventional glow engine. Therefore, the glow ignition engine can be appropriately driven by an inexpensive low ignition point fuel.

1 is a schematic cross-sectional view of a glow ignition engine according to a first embodiment. Expanded sectional view of glow plug Expanded cross section of adapter Explanatory diagram when energizing the glow plug using a booster Cross-sectional schematic diagram of a glow ignition engine according to the second embodiment

(First embodiment)
FIG. 1 is a schematic cross-sectional view of a glow ignition engine according to the first embodiment. In this embodiment, the engine of the present invention is referred to as a glow ignition engine in order to distinguish it from a conventional glow engine. The glow ignition engine 1 is a two-stroke engine, and includes a cylinder 2, a piston 3, a glow plug 4, and an adapter 5. A combustion chamber 6 is formed by the cylinder 2 and the piston 3. In the combustion chamber 6, gasoline as a low ignition point fuel is supplied. The combustion chamber 6 may be supplied with other low ignition point fuel such as LP gas or kerosene. The glow ignition engine 1 has the same configuration as that of a conventional two-stroke engine having an ignition device except for the glow plug 4 and the adapter 5.

  The cylinder 2 is configured by screwing the cylinder block 21 and the cylinder head 22 together. In the cylinder head 22, a screw hole 22A having an inner diameter corresponding to a screw formed in the spark plug is formed so as to penetrate into the combustion chamber 6 along the axial direction of the cylinder 2 (vertical direction in FIG. 1). Yes. The spark plug is a plug that constitutes a part of the ignition device and ignites the fuel by sparking a spark, and is generally used in a gasoline engine or the like. This spark plug has an outer diameter larger than the outer diameter of the glow plug 4. The piston 3 is provided in the cylinder 2 so as to be slidable along the axial direction of the cylinder 2 from the top dead center to the bottom dead center. Here, FIG. 1 is an enlarged view of the vicinity of the combustion chamber 6 when the piston 3 is at the top dead center in the glow ignition engine 1. The glow plug 4 ignites gasoline and is fixed to the cylinder head 22 via the adapter 5.

  FIG. 2 is an enlarged cross-sectional view of the glow plug 4. The glow plug 4 is a plug that ignites the fuel by maintaining a red-hot state using combustion heat when the fuel burns. The glow plug 4 includes a center electrode 41, a filament 42, and a plug housing 43. The center electrode 41 is formed in a columnar shape having a portion whose diameter is increased at a substantially central position, and is fixed inside the plug housing 43 via an insulator. A planar notch 41A is formed along the axial direction at the end of the center electrode 41 on the piston 3 side. One end of the filament 42 is linearly welded along the axial direction of the center electrode 41 to the notch 41A. By welding the filament 42 in this way, the fixing strength of the filament 42 can be improved. The other end of the filament 42 is welded to the tip of the plug housing 43 on the piston 3 side. The plug housing 43 is formed in a substantially cylindrical shape, and houses the center electrode 41 and the filament 42 therein. The plug housing 43 has a distal end portion 43A formed on the piston 3 side. On the outer peripheral surface of the distal end portion 43A, a screw is formed in a substantially half region located on the proximal end side. The proximal end side of the distal end portion 43A is formed in a hexagonal nut shape.

  FIG. 3 is an enlarged cross-sectional view of the adapter 5. The adapter 5 fixes the glow plug 4 to the cylinder head 22 by being interposed between the cylinder head 22 and the glow plug 4. Specifically, the adapter 5 is formed in a substantially cylindrical shape with a material having a lower thermal conductivity than the aluminum cylinder head 22. Examples of the material having a lower thermal conductivity than the cylinder head 22 include iron, titanium, SUS (Stainless Used Steel), and brass. According to this, since the heat of the glow plug 4 is difficult to be transmitted to the cylinder head 22, it becomes easy to maintain a red hot state. Therefore, the adapter 5 functions as a heat retaining member that retains the glow plug 4.

  The adapter 5 has an inner diameter larger than the outer diameter of the glow plug 4 and includes a cutout portion 51, a male screw portion 52, a nut portion 53, and a fixing portion 54. The notch 51 is formed in a tapered shape at the end on the piston 3 side. The male screw portion 52 is formed at a substantially central position on the outer peripheral surface, and has an outer diameter corresponding to the inner diameter of the screw hole 22 </ b> A in the cylinder head 22. According to this, a glow ignition engine can be comprised by removing an ignition device from the conventional engine which has an ignition device, and attaching the adapter of this invention. The nut portion 53 is formed in a hexagonal nut shape at the end opposite to the piston 3. The fixing portion 54 is formed in an internal thread shape on the inner peripheral surface of the adapter 5, and fixes the glow plug 4 to the inside of the adapter 5. The fixing portion 54 has an inner diameter corresponding to the outer diameter of the screw formed at the tip portion 43A of the glow plug 4.

  The glow plug 4 is fixed inside the adapter 5 by screwing the distal end portion 43 </ b> A into the fixing portion 54. At this time, the glow plug 4 is positioned with respect to the adapter 5 by the end surface of the portion formed in a hexagonal nut shape coming into contact with the fixing portion 54. Further, the reach of the glow plug 4, that is, the length of the distal end portion 43 </ b> A in the axial direction is longer than the length of the fixed portion 54. Therefore, the filament 42 and the distal end portion 43 </ b> A protrude with respect to the adapter 5.

  The adapter 5 is fixed to the cylinder head 22 by rotating the nut portion 53 and screwing the male screw portion 52 into the screw hole 22A (see FIG. 1). At this time, the adapter 5 is positioned with respect to the cylinder head 22 by the end surface of the nut portion 53 coming into contact with the cylinder head 22. In the adapter 5, the length in the axial direction of the portion excluding the nut portion 53 is longer than the length of the screw hole 22A. Therefore, the glow plug 4 and the adapter 5 protrude into the combustion chamber 6 and face the piston 3. Further, the glow plug 4 and the adapter 5 project into the combustion chamber 6, so that the compression ratio of the glow ignition engine 1 is increased. As a result, the output of the glow ignition engine 1 is improved as compared with the conventional glow engine in which the tip of the glow plug and the wall surface of the combustion chamber substantially coincide. Here, in the present embodiment, the length of the adapter 5 in the axial direction and the length of the fixing portion 54 are set so that the timing of ignition of gasoline becomes an appropriate timing, and the amount of protrusion of the glow plug 4 is set. It prescribes. That is, the adapter 5 has a function of adjusting the protruding amount of the glow plug 4 by changing its shape. Further, the length of the adapter 5 in the axial direction and the outer diameter of the adapter 5 are set so that the combustion condition of gasoline is appropriate, and the compression ratio of the glow ignition engine 1 is defined. That is, the adapter 5 has a function of adjusting the compression ratio of the glow ignition engine 1 without changing the shape of the combustion chamber 6 by changing its shape. The protruding amount of the glow plug 4 and the compression ratio of the glow ignition engine 1 may be optimized according to the type of low ignition point fuel, the engine type, and the like.

  FIG. 4 is an explanatory diagram when energizing the glow plug 4 using a booster. The booster 7 is an instrument that energizes the glow plug 4. The booster 7 includes a grip portion 71 and a connection portion 72. The grip portion 71 is gripped by the user of the glow ignition engine 1. The gripping unit 71 has a built-in battery (not shown) for applying a voltage. The connecting portion 72 is formed in a cylindrical shape, and is connected to the center electrode 41 and the plug housing 43 and applies a voltage to energize the glow plug 4. That is, the plug housing 43 functions as an electrode. When the glow plug 4 is energized, the filament 42 becomes red hot and ignites the gasoline. Thereby, the glow ignition engine 1 is started. Here, the adapter 5 has an inner diameter slightly larger than the outer diameter of the connection portion 72. When energizing the glow plug 4, the connecting portion 72 is inserted into the adapter 5, that is, into the groove. Thereby, the connecting portion 72 is guided to the electrode of the glow plug 4 along the depth of the groove of the adapter 5. In other words, the inside of the adapter 5 functions as a guide portion provided around the electrode of the glow plug 4 exposed outside the cylinder 2. Therefore, the connecting portion 72 can be reliably connected to the electrode of the glow plug 4. Further, since the connecting portion 72 is fitted into the adapter 5, the connecting portion 72 is not detached from the glow plug 4 due to the vibration of the cylinder 2 when the glow ignition engine 1 is started. Can be energized.

  As described above, according to the present embodiment, the adapter 5 causes the tip portion 43A for igniting gasoline to protrude into the combustion chamber 6, so that the ignition timing for gasoline can be made earlier than the conventional glow engine. it can. Therefore, the glow ignition engine 1 can be appropriately driven even by cheap gasoline.

(Second Embodiment)
FIG. 5 is a schematic cross-sectional view of the glow ignition engine 1 according to the second embodiment. The feature of this embodiment is that the screw hole 22A is inclined with respect to the axial direction of the cylinder 2. Here, the reason why the screw hole 22A is inclined is that the size of the engine in the axial direction of the cylinder 2 can be reduced by inclining the spark plug and fixing it to the cylinder head 22. Since the rest is the same as that of the first embodiment described above, the description thereof is omitted here.

  Thus, according to the present embodiment, the same operational effects as those of the first embodiment described above can be achieved. Moreover, since the adapter 5 has the notch part 51 formed so that it may not interfere with the piston 3 when it exists in a top dead center, compared with the case where the notch part 51 is not provided, the glow plug 4 of FIG. The tip portion 43A can be brought close to the piston 3.

  In each of the embodiments described above, the glow plug 4 is fixed inside the adapter 5 by screwing the distal end portion 43 </ b> A to the fixing portion 54. On the other hand, for example, the glow plug may be fixed by fitting into the adapter without forming a screw in the glow plug. The adapter 5 is fixed to the cylinder head 22 by screwing the male screw portion 52 into the screw hole 22A. On the other hand, for example, the adapter may be fixed by fitting into the cylinder without forming the male screw portion in the adapter. In short, the adapter is only required to be able to fix the glow plug to the cylinder by being interposed between the cylinder and the glow plug, and the glow plug and the adapter may have any shape. .

  Moreover, in each embodiment mentioned above, although the adapter 5 was formed with the material whose heat conductivity is lower than the cylinder 2, it is formed with the same material as the cylinder 2, or a material with higher heat conductivity than the cylinder 2. It may be. Further, the notch 51 is formed in a tapered shape, but may be formed so as not to interfere with the piston 3 at the top dead center, and at least a part of the edge of the adapter 5 on the piston 3 side. What is necessary is just to be formed. Note that the adapter 5 may not have the notch 51. Further, although the adapter 5 has an inner diameter slightly larger than the outer diameter of the connection portion 72, the adapter 5 only needs to have an inner diameter larger than the outer diameter of the connection portion 72.

  In each of the above-described embodiments, the length of the adapter 5 in the axial direction and the length of the fixed portion 54 in the axial direction are set so that the timing at which gasoline is ignited is appropriate. The amount of protrusion was regulated. On the other hand, the amount of protrusion of the glow plug may be defined by setting the reach of the glow plug and the length of the screw hole of the cylinder head in the axial direction.

  Moreover, in each embodiment mentioned above, although the 2-stroke engine was illustrated as the glow ignition engine 1, you may apply this invention to a 4-stroke engine.

  As described above, the present invention can be widely applied to a glow ignition engine that ignites fuel with a glow plug.

DESCRIPTION OF SYMBOLS 1 Glow ignition engine 2 Cylinder 3 Piston 4 Glow plug 5 Adapter 6 Combustion chamber 7 Booster 21 Cylinder block 22 Cylinder head 22A Screw hole 41 Center electrode 41A Notch part 42 Filament 43 Plug housing 43A Tip part 51 Notch part 52 Male thread part 53 Nut Part 54 fixing part 71 gripping part 72 connecting part

Claims (5)

In the glow ignition engine,
A cylinder,
A piston provided in the cylinder;
A glow plug that is supplied into a combustion chamber formed by the cylinder and the piston and ignites at a tip portion thereof a fuel having an ignition point lower than that of the glow fuel;
A glow ignition engine comprising: an adapter for fixing the glow plug to the cylinder by being interposed between the cylinder and the glow plug and causing the tip portion to protrude into the combustion chamber. The adapter has a fixing portion for fixing the glow plug inside the adapter, and is formed in a cylindrical shape having a screw that penetrates into the combustion chamber and is screwed into a screw hole formed in the cylinder on an outer peripheral surface. And
2. The fixing part is configured to fix the glow plug by screwing a screw formed on an outer peripheral surface of the glow plug with a screw formed on an inner peripheral surface of the adapter. Glow ignition engine described in 1.   3. The glow according to claim 2, wherein the adapter has a notch formed in at least a part of an edge portion on the piston side so as not to interfere with the piston when the adapter is at the top dead center. Ignition engine.   The adapter has a guide portion including a groove for inserting a booster for energizing the glow plug by being connected to an electrode of the glow plug, and the guide portion extends the booster along the depth of its own groove. The glow ignition engine according to claim 2, wherein the glow ignition engine is led to the electrode.   The glow ignition engine according to any one of claims 1 to 4, wherein the adapter is formed of a material having a lower thermal conductivity than a material of the cylinder.

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