Heating device for internal combustion engines

Abstract

To provide a heating device for an internal combustion engine which is capable of efficient heating.SOLUTION: A heating device for an internal combustion engine includes a conductor wire provided outside of a plurality of cylinders of an internal combustion engine, and an electric power source which supplies AC power to the conductor wire. The conductor wire is provided like a figure eight between two adjacent cylinders, thereby forming a plurality of coils corresponding to the plurality of cylinders.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a heating device for an internal combustion engine. [Background technology]

[0002] BACKGROUND ART There is known a technique for inductively heating a cylinder of an internal combustion engine by supplying AC power to a coiled conductor (for example, see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-120376 Summary of the Invention [Problem to be solved by the invention]

[0004] By heating the cylinder, unburned fuel in the cylinder can be vaporized. This can suppress the generation of particulate matter (PM) from unburned fuel. However, it has been difficult to heat the cylinder efficiently. Therefore, the object of this invention is to provide a heating device for an internal combustion engine that can heat the cylinder efficiently. [Means for solving the problem]

[0005] The above object can be achieved by a heating device for an internal combustion engine, comprising conductors arranged outside a plurality of cylinders of the internal combustion engine, and a power source that supplies AC power to the conductors, the conductors being arranged in an eight-shaped configuration between two adjacent cylinders, thereby forming a plurality of coils corresponding to the plurality of cylinders.

[0006] A direction across the row of cylinders may be defined as a first direction, a direction opposite to the first direction may be defined as a second direction, and the conductor may be arranged to travel back and forth across the row of cylinders along the first direction and the second direction.

[0007] The wall of the cylinder may be formed of a first metal layer and a second metal layer, the first metal layer being located outside the second metal layer, the second metal layer having a protrusion at a position opposite the coil, and the protrusion protruding to the outside and penetrating the first metal layer.

[0008] The second metal layer may have a higher volume resistivity than the first metal layer. [Effects of the Invention]

[0009] A heating device for an internal combustion engine that is capable of efficient heating can be provided. [Brief explanation of the drawings]

[0010] [Figure 1] Fig. 1(a) is a side view illustrating a heating device for an internal combustion engine according to the first embodiment, Fig. 1(b) and Fig. 1(c) are plan views illustrating the heating device. [Figure 2] FIG. 2 is a plan view illustrating a heating device according to a comparative example. [Figure 3] Fig. 3(a) is a side view illustrating a heating device for an internal combustion engine according to the second embodiment, and Fig. 3(b) is a cross-sectional view illustrating one cylinder. DETAILED DESCRIPTION OF THE INVENTION

[0011] The heating device for an internal combustion engine according to this embodiment will be described below with reference to the drawings. However, the dimensions and ratios of the various parts in the drawings may not be exactly the same as those in reality. Also, some details may be omitted in some drawings.

[0012] First Embodiment FIG. 1(a) is a side view illustrating a heating device 100 for an internal combustion engine according to a first embodiment. FIG. 1(b) is a plan view illustrating the heating device 100. The internal combustion engine is, for example, a four-cylinder engine having four cylinders #1, #2, #3, and #4. A piston (not shown) reciprocates in each cylinder. The four cylinders are arranged in a row. The direction from left to right in FIGS. 1(a) and 1(b) is defined as the X1 direction (first direction). The direction from right to left is defined as the X2 direction (second direction).

[0013] Cylinders #1, #2, #3, and #4 are arranged in this order along the X1 direction. Cylinders #4, #3, #2, and #1 are arranged in this order along the X2 direction. The axes of the cylinders are parallel to the Z1 and Z2 directions. The Z1 direction is the upward direction in Figure 1(a). The Z2 direction is the downward direction, opposite to the Z1 direction. The Y direction is perpendicular to the plane of the paper in Figure 1(a) and is perpendicular to the X1, X2, Z1, and Z2 directions.

[0014] The heating device 100 has a power supply 10 and a conductor 11. The power supply 10 includes a battery and a drive circuit and supplies AC power. The battery stores power. The drive circuit is electrically connected to the conductor 11 and uses the power from the battery to cause a current to flow through the conductor 11. The drive circuit turns the current on and off.

[0015] Conductor 11 is made of metal and is provided outside the four cylinders, and is disposed inside a water jacket (not shown). Conductor 11 travels back and forth between the rows of cylinders along the X1 and X2 directions. Conductor 11 is divided into two equal parts, conductor 12 and conductor 14. In Figures 1(a) and 1(b), conductor 12 is shown by a solid line, and conductor 14 is shown by a dashed line. Conductor 12 extends from power source 10 to cylinder #4. Conductor 14 turns back from cylinder #4 and extends to power source 10.

[0016] As shown in FIG. 1(a), the conductors 12 and 14 are arranged in a wavy pattern. The conductor 14 is arranged in a wavy pattern that is out of phase with the conductor 12. The conductor 12 is convex in the Z2 direction near cylinders #1 and #3 and convex in the Z1 direction near cylinders #2 and #4. The conductor 14 is convex in the Z1 direction near cylinders #1 and #3 and convex in the Z2 direction near cylinders #2 and #4. The conductors 12 and 14 are arranged in an 8-shape between cylinders #1 and #2. The conductors 12 and 14 are arranged in an 8-shape between cylinders #2 and #3. The conductors 12 and 14 are arranged in an 8-shape between cylinders #3 and #4.

[0017] Conductor wires 12 and 14 form coil 20 near cylinder #1. Conductor wires 12 and 14 form coil 22 near cylinder #2. Conductor wires 12 and 14 form coil 24 near cylinder #3. Conductor wires 12 and 14 form coil 26 near cylinder #4. The central axes of the coils are parallel to the Y direction.

[0018] As shown in FIG. 1(b), each of the four cylinders has an intake port 30, an exhaust port 32, and a fuel injection valve 34. Two intake ports 30 and two exhaust ports 32 are located on the ceiling of the cylinder on the Z1 side. The two intake ports 30 are aligned in the X1 and X2 directions. The two exhaust ports 32 are aligned in the X1 and X2 directions. The conducting wire 11 faces a portion of the cylinder wall close to the exhaust port 32.

[0019] The fuel injection valve 34 is located between the two intake ports 30. The tip of the fuel injection valve 34 faces the part of the cylinder wall on the exhaust port 32 side. The fuel injection valve 34 injects fuel from the tip toward the inside of the cylinder.

[0020] The wall of the cylinder has two metal layers 40 and 42. Metal layer 40 (first metal layer) forms the outer wall of the cylinder. Metal layer 42 (second metal layer) is a cylinder liner, and is provided inside metal layer 40 to form the inner wall. Metal layer 42 is, for example, cylindrical. Metal layer 40 is made of, for example, aluminum (Al). Metal layer 42 is made of, for example, iron (Fe).

[0021] FIG. 1(c) is a plan view illustrating the heating device 100, omitting the intake port 30, the exhaust port 32, and the fuel injector 34. The drive circuit of the power source 10 outputs AC power. An AC current flows through the conductor 11. The AC current generates a magnetic field in the coil. The current flows from the power source 10 to the conductor 12 and then through the conductor 14 toward the power source 10. As shown in FIG. 1(c), the magnetic field H1 passes through the coil 20 and faces away from the cylinder #1. The magnetic field H2 faces in the opposite direction to the magnetic field H1, passes through the coil 22, and faces toward the cylinder #2. The magnetic field H3 faces in the opposite direction to the magnetic field H2, passes through the coil 24, and faces away from the cylinder #3. The magnetic field H4 faces in the opposite direction to the magnetic field H3, passes through the coil 26, and faces toward the cylinder #4.

[0022] The dashed lines in Figure 1(c) represent magnetic field lines. The magnetic field lines pass between magnetic field H1 and magnetic field H2, between magnetic field H2 and magnetic field H3, and between magnetic field H3 and magnetic field H4. The magnetic field lines pass through the cylinder wall closest to the coil and the wall between two adjacent cylinders. The drive circuit reverses the direction of the AC current at a frequency of, for example, several tens of kHz. Reversing the direction of the AC current also reverses the direction of the magnetic field.

[0023] When the magnetic field passes through the metal layers 40 and 42 of the cylinder, eddy currents are generated in the metal layers 40 and 42. The flow of eddy currents causes the metal layers 40 and 42 to heat up. The heat vaporizes the unburned fuel in the cylinder. Vaporizing the unburned fuel reduces the generation of particulate matter (PM).

[0024] (Comparative Example) 2 is a plan view illustrating a heating device according to a comparative example. Conductive wire 11 forms coil 27. Coil 27 is located outside the four cylinders and is arranged across the row of cylinders. In other words, one coil 27 is provided for four cylinders.

[0025] When an alternating current flows through the conductor 11, a magnetic field is generated that penetrates the coil 27. The magnetic field lines propagate outside the cylinder. As the path of the magnetic field lines becomes longer, they disperse. As fewer magnetic field lines pass through the cylinder wall, eddy currents decrease. As eddy currents become smaller, the amount of heat generated decreases. Unburned fuel is less likely to vaporize and remains in the cylinder. When unburned fuel is ignited, there is a risk that PM will be generated from the unburned fuel.

[0026] According to the first embodiment, the heating device 100 has a power source 10 and a conductor 11. The conductor 11 forms multiple coils corresponding to multiple cylinders. Coil 20 is located near cylinder #1. Coil 22 is located near cylinder #2. Coil 24 is located near cylinder #3. Coil 26 is located near cylinder #4. As shown in Figure 1(c), magnetic field lines have difficulty passing outside the cylinder and tend to pass through the cylinder wall. Because the magnetic field lines pass through the cylinder wall in a concentrated manner, efficient heating is possible. The passage of the magnetic field lines causes eddy currents to flow in the cylinder wall, generating heat. The heat can burn unburned fuel in the cylinder. The generation of PM caused by unburned fuel can be suppressed.

[0027] The conductor 11 is arranged in a figure-8 shape between two adjacent cylinders. A coil is formed corresponding to each cylinder. A magnetic field is generated from one coil corresponding to one cylinder. The magnetic field is reversed between adjacent coils. Since the magnetic field lines can easily pass through the cylinders, the cylinders can be heated efficiently.

[0028] As shown in Figure 1(c), the magnetic field lines pass through the cylinder wall near the coil and also through the wall between adjacent cylinders. Eddy currents are generated in the wall where the magnetic field lines pass, causing it to heat up. Unburned fuel is burned and removed.

[0029] As shown in FIG. 1(b), the tip of the fuel injection valve 34 faces the exhaust port 32. Unburned fuel tends to adhere to the part of the cylinder wall that is close to the exhaust port 32. The part of the cylinder wall that is close to the exhaust port 32 is easily heated by the magnetic field lines passing through it. This allows the unburned fuel to be effectively burned. The position of the conductor 11 may be changed depending on the orientation of the fuel injection valve 34. The conductor 11 is placed near the part of the cylinder where fuel tends to adhere.

[0030] Conductor 11 travels back and forth between the rows of cylinders in the X1 and X2 directions. Conductor 12 extends from power source 10 to the rows of cylinders. Conductor 14 folds back from conductor 12 and extends to power source 10. Coils are formed corresponding to each cylinder. A magnetic field is generated from one coil corresponding to each cylinder. Since the magnetic field lines can easily pass through the cylinders, the cylinders can be heated efficiently.

[0031] As shown in Figure 1(a), the conductor 11 goes back and forth through the row of cylinders once. Each coil has one turn. The conductor 11 may go back and forth through the row of cylinders two or more times. The number of turns in the coil is two or more. The more turns there are, the stronger the magnetic field and the larger the induced current. The amount of heat generated increases.

[0032] The coil is positioned above the surface of the piston at bottom dead center. Unburned fuel tends to adhere to the part of the cylinder above the cylinder. The magnetic field generated by the coil causes eddy currents to flow in the part of the cylinder above the bottom dead center, generating heat. This allows the unburned fuel to be burned effectively. The number of cylinders can be four or less, or more than four. The number of coils is equal to the number of cylinders. One coil is placed per cylinder.

[0033] Second Embodiment Fig. 3(a) is a side view illustrating a heating device 200 for an internal combustion engine according to a second embodiment. Fig. 3(b) is a cross-sectional view illustrating one cylinder #1. Descriptions of the same configuration as in the first embodiment will be omitted.

[0034] As shown in Figures 3(a) and 3(b), each cylinder is provided with a protrusion 44. As shown in Figure 3(a), the protrusion 44 forms a ring on the side surface of the cylinder, facing the coil.

[0035] As shown in Figure 3(b), the metal layer 42 has protrusions 44. That is, the protrusions 44 are part of the metal layer 42 and are made of, for example, Fe. The protrusions 44 penetrate the metal layer 40 and reach the outer wall of the cylinder. The surface of the protrusions 44 is exposed to the outside and becomes part of the outer wall of the cylinder.

[0036] According to the second embodiment, the metal layer 42 of the cylinder has protrusions 44. In the Y-axis direction, the protrusions 44 penetrate the metal layer 40 and face the coil 20. When a current flows through the coil 20, a magnetic field is generated. When magnetic field lines pass through the protrusions 44, eddy currents flow in the metal layer 42. Heat is generated in the metal layer 42. In the other three cylinders, the metal layer 42 is heated in the same way when magnetic field lines pass through the protrusions 44. The inner wall of the cylinder is heated, and unburned fuel inside the cylinder is burned.

[0037] The lower the frequency of the AC current, the lower the skin effect. Magnetic flux penetrates metal layer 40 and more easily passes through metal layer 42. However, as the frequency decreases, eddy currents decrease and the amount of heat generated also decreases. For example, increasing the current flowing through conductor 11 increases the magnetic field and eddy currents. However, magnetic flux is more likely to leak outside the cylinder. When the frequency is high, the skin effect increases and eddy currents are more likely to occur on the outer surface of the cylinder. For example, if metal layer 40 is made of Al and covers the entire outer wall of the cylinder, eddy currents will flow in metal layer 40. The volume resistivity of Al is lower than that of Fe, etc., so the amount of heat generated is low. It is difficult to heat the cylinder sufficiently.

[0038] According to the second embodiment, the protrusions 44 of the metal layer 42 are part of the outer wall of the cylinder. The frequency is increased, for example, to 20 kHz or higher. The skin effect is strengthened, and eddy currents flow to the protrusions 44. Heat generated in the protrusions 44 is transferred to the inner wall of the cylinder (metal layer 42). The metal layer 42 is formed of, for example, Fe. The volume resistivity of the metal layer 42 is higher than the volume resistivity of the metal layer 40. The amount of heat generated in the metal layer 42 is large, so the inside of the cylinder can be sufficiently heated. By heating the inside of the cylinder, unburned fuel can be burned.

[0039] The metal layer 40 may be formed of a metal other than Al. The metal layer 42 may be formed of a metal other than Fe. The volume resistivity of the metal layer 42 is higher than the volume resistivity of the metal layer 40.

[0040] The coil and the protrusions 44 are positioned above the surface of the piston at bottom dead center. The magnetic field generated by the coil heats the protrusions 44. Heat is easily transferred to the metal layer 42 at a position above bottom dead center in the cylinder. This allows unburned fuel to be burned effectively.

[0041] As shown in Figure 3(a), the protrusions 44 are arranged in a ring shape and face the coil. This increases the proportion of the outer wall of the cylinder occupied by the protrusions 44. This makes it easier for magnetic flux to pass through the protrusions 44. This increases the amount of heat generated.

[0042] Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and variations are possible within the scope of the gist of the present invention as described in the claims. [Explanation of symbols]

[0043] Cylinders #1, #2, #3, #4, 10 power supply, 11, 12, 14 wire, 20, 22, 24, 26, 27 coil, 30 intake port, 32 exhaust port, 34 fuel injection valve, 40, 42 metal layer, 44 protrusion, 100, 200 heating device

Claims

1. a conductor disposed outside a plurality of cylinders of the internal combustion engine; a power source that supplies AC power to the conductor; A heating device for an internal combustion engine, wherein the conducting wire is arranged in a figure-eight shape between two adjacent cylinders, thereby forming a plurality of coils corresponding to the plurality of cylinders.

2. a first direction is a direction that crosses the row of the plurality of cylinders; a second direction opposite to the first direction; 2. The heating device for an internal combustion engine according to claim 1, wherein the conductor is provided so as to reciprocate through the rows of the plurality of cylinders along the first direction and the second direction.

3. the wall of the cylinder is formed of a first metal layer and a second metal layer; the first metal layer is located outside the second metal layer, the second metal layer has a protrusion at a position facing the coil, 3. The heating device for an internal combustion engine according to claim 1, wherein the protrusion protrudes outward and penetrates the first metal layer.

4. 4. The heating device for an internal combustion engine according to claim 3, wherein the volume resistivity of the second metal layer is higher than the volume resistivity of the first metal layer.

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