Internal combustion engine

Abstract

To provide an internal combustion engine improved in strength of a cylinder block.SOLUTION: The internal combustion engine 1 includes a cylinder block 9. The cylinder block 9 includes a cylinder liner 10 having an outer peripheral surface 13, a facing wall 14 facing the outer peripheral surface 13, a water jacket 11 defined by the outer peripheral surface 13 and the facing wall 14, and a heater 15 housed in the water jacket 11 in a state of being in contact with the outer peripheral surface 13.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an internal combustion engine. [Background technology]

[0002] Patent Document 1 discloses an internal combustion engine equipped with a heater that heats the bore wall of a cylinder block. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-171886 Summary of the Invention [Problem to be solved by the invention]

[0004] The internal combustion engine described in Patent Document 1 has a space provided in the bore wall of the cylinder block to accommodate the heater, which reduces the strength of the cylinder block. [Means for solving the problem]

[0005] An internal combustion engine that solves the above problem includes a cylinder block, the cylinder block including a cylinder liner having an outer peripheral surface, an opposing wall opposing the outer peripheral surface, a water jacket defined by the outer peripheral surface and the opposing wall, and a heater housed in the water jacket in contact with the outer peripheral surface. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a cross-sectional view of a cylinder block. [Figure 2] FIG. 2 is a cross-sectional view taken along line 2-2 of FIG. [Figure 3] FIG. 3 is a schematic diagram showing the positional relationship between the axis of the piston, a first imaginary plane, and a second imaginary plane. DETAILED DESCRIPTION OF THE INVENTION

[0007] An embodiment of an internal combustion engine will be described below with reference to the drawings. <Overall configuration of an internal combustion engine> 1, the internal combustion engine 1 includes a cylinder block 9, a cylinder head 8, and a piston 16. The cylinder block 9 includes a cylinder liner 10. The piston 16 is housed inside the cylinder liner 10. The internal combustion engine 1 includes a combustion chamber 21. The combustion chamber 21 is defined by an inner circumferential surface 12 of the cylinder liner 10, the piston 16, and the cylinder head 8.

[0008] The cylinder head 8 is attached to a cylinder block 9. The internal combustion engine 1 is equipped with an injector 31 and a spark plug 3. The spark plug 3 is housed in the lower center of the cylinder head 8.

[0009] <Piston> The piston 16 is equipped with three piston rings 20. The piston 16 changes the volume of the combustion chamber 21 as it reciprocates. Top dead center is the position of the piston when the volume of the combustion chamber 21 is minimum. Bottom dead center is the position of the piston when the volume of the combustion chamber 21 is maximum.

[0010] The top of piston 16 includes a concave surface 18, a top surface 17, and a tapered surface 19. The concave surface 18 is located at the center of the top of piston 16 and is a curved surface that is concave toward the opposite side from the spark plug 3 in the direction along the axis AL of piston 16. The axis AL of piston 16 is an imaginary line that passes through the center of the top of piston 16 and extends in the direction in which piston 16 reciprocates. The top surface 17 is continuous with the concave surface 18 and is an annular flat surface that surrounds the concave surface 18. The top surface 17 is perpendicular to the axis AL of piston 16. The tapered surface 19 is continuous with the top surface 17 and is an annular curved surface that surrounds the top surface 17.

[0011] The cylinder head 8 has an intake port 5 and an exhaust port 7. The intake port 5 introduces intake air into the combustion chamber 21. The intake port 5 has an intake valve 4 at its opening to the combustion chamber 21. The intake valve 4 opens during the intake stroke of the internal combustion engine 1, thereby connecting the combustion chamber 21 and the intake port 5.

[0012] The exhaust port 7 discharges exhaust gas from the combustion chamber 21. The exhaust port 7 is equipped with an exhaust valve 6 at its opening to the combustion chamber 21. The exhaust valve 6 opens during the exhaust stroke of the internal combustion engine 1, thereby connecting the combustion chamber 21 with the exhaust port 7. The internal combustion engine 1 is equipped with two intake valves 4 and two exhaust valves 6. FIG. 1 shows only one intake valve 4 and one exhaust valve 6.

[0013] <Injector> As shown in Fig. 2, the injector 31 is housed in the cylinder head 8 between the two intake valves 4. The injector 31 has a nozzle hole 32 at the tip of the injector 31. The injector 31 is a direct injection injector that injects fuel from the nozzle hole 32 into the inside of the cylinder liner 10, i.e., toward the combustion chamber 21.

[0014] <Water jacket> The cylinder block 9 includes a water jacket 11 and two heaters 15. The cylinder block 9 includes an opposing wall 14 that faces an outer peripheral surface 13 of the cylinder liner 10. The opposing wall 14 is provided outside the outer peripheral surface 13 of the cylinder liner 10 in the radial direction of the piston 16.

[0015] The water jacket 11 is a passage for cooling water to cool the cylinder block 9. The water jacket 11 is defined by an outer peripheral surface 13 of the cylinder liner 10 and an opposing wall 14. The water jacket 11 and the opposing wall 14 surround the outer peripheral surface 13 of the cylinder liner 10 over the entire circumferential direction of the piston 16.

[0016] <Heater> The two heaters 15 are housed in the water jacket 11 with a gap between them in the direction along the axis AL. An example of the heater 15 is an electric heater. An example of the electric heater is a heater that generates heat by passing an electric current through a heating wire. The heater 15 is, for example, a sheet-like heater that is in surface contact with the outer circumferential surface 13. The internal combustion engine 1 is equipped with a power source that supplies power to the heater 15.

[0017] The heater 15 is disposed so as not to block the cooling water flow path within the water jacket 11. For example, the thickness of the heater 15 is thinner than the distance between the outer peripheral surface 13 of the cylinder liner 10 and the opposing wall 14. Therefore, a gap exists between the heater 15 and the opposing wall 14 through which the cooling water can pass. This reduces the flow resistance of the cooling water when it flows through the water jacket 11. Furthermore, because the heater 15 is not in contact with the opposing wall 14, the heat of the heater 15 is not easily transferred to the opposing wall 14 but is easily transferred to the outer peripheral surface 13 of the cylinder liner 10.

[0018] As shown in Figures 1 to 3, the direction along the axis AL of the piston 16 is referred to as the axis AL direction. In the axis AL direction, the position of the top surface 17 when the piston 16 is located at bottom dead center is referred to as the bottom dead center position BP. The line segment connecting the axis AL of the piston 16 to the nozzle hole 32 is referred to as the imaginary line segment LS. An imaginary plane that includes the axis AL of the piston 16 and intersects the imaginary line segment LS perpendicularly is referred to as the first imaginary plane VP1. An imaginary plane that includes the axis AL of the piston 16 and intersects the first imaginary plane VP1 perpendicularly is referred to as the second imaginary plane VP2.

[0019] <Fuel adhesion surface and contact surface> The inner circumferential surface 12 of the cylinder liner 10 includes a fuel adhesion surface 121 to which liquid fuel injected from the injector 31 adheres. Of the inner circumferential surface 12 of the cylinder liner 10, the fuel adhesion surface 121 is more likely to receive liquid fuel than other portions. An example of the fuel adhesion surface 121 is a portion of the inner circumferential surface 12 that satisfies at least condition (A) of the following conditions (A) and (B). It is desirable that the fuel adhesion surface 121 also satisfies condition (B).

[0020] Condition (A): A portion located closer to the nozzle hole 32 of the injector 31 than the bottom dead center position BP in the direction of the axis AL. Condition (i) Of the two semi-cylindrical surfaces CS1 and CS2 obtained by equally dividing the inner surface 12 by the first imaginary plane VP1, this is the part corresponding to the semi-cylindrical surface CS1 located on the opposite side of the nozzle hole 32 with respect to the axis AL of the piston 16.

[0021] Hereinafter, the portion of the outer peripheral surface 13 of the cylinder liner 10 that is located on the opposite side of the fuel attachment surface 121 in the radial direction of the piston 16 will be referred to as the opposite surface 130. Heat from the opposite surface 130 is easily transferred to the fuel attachment surface 121. Therefore, by heating the opposite surface 130, the temperature of the fuel attachment surface 121 increases.

[0022] The contact surface 131 is a portion of the outer peripheral surface 13 of the cylinder liner 10 where the heater 15 and the cylinder liner 10 are in contact. The contact surface 131 includes the opposite surface 130. When the contact surface 131 includes the opposite surface 130, only a portion of the contact surface 131 may be the opposite surface 130, or the entire contact surface 131 may be the opposite surface 130. It is desirable that the contact surface 131 include an intersection line 132 between the second imaginary plane VP2 and the opposite surface 130.

[0023] <Effects of this embodiment> (1) Heating by the heater 15 raises the temperature of the outer peripheral surface 13 of the cylinder liner 10. This allows liquid fuel adhering to the inner peripheral surface 12 of the cylinder liner 10 to be vaporized. The heater 15 is housed in the water jacket 11. This reduces the strength of the cylinder block 9 compared to a configuration in which a separate space for housing the heater 15 is provided in the cylinder block 9.

[0024] (2) Since the contact surface 131 includes the opposite surface 130, the temperature of the fuel adhering surface 121 increases due to the heat from the heater 15. As a result, more fuel can be vaporized.

[0025] <Example of change> This embodiment can be modified as follows: This embodiment and the following modifications can be combined and implemented within the scope of technical compatibility.

[0026] The internal combustion engine 1 may be equipped with a port injection injector that injects fuel into the intake port 5 instead of or in addition to the direct injection injector 31. The fuel injected from the port injection injector is mixed with the air flowing through the intake port 5 and then introduced into the combustion chamber 21. A portion of the fuel introduced into the combustion chamber 21 remains in liquid form and adheres to the inner surface 12 of the cylinder liner 10. The liquid fuel injected from the port injection injector and adhering to the inner surface 12 can be vaporized by heating with the heater 15.

[0027] The contact surface 131 between the heater and the cylinder liner 10 does not have to include the intersection line 132. The heater 153 shown in Figure 2 is an example of a heater with this configuration. The fuel adhesion surface 121 may be one of two semi-cylindrical surfaces CS1, CS2 obtained by equally dividing the inner circumferential surface 12 by a first imaginary plane VP1, the semi-cylindrical surface CS2 being located closer to the nozzle hole 32 with respect to the axis AL of the piston 16. The heater 152 shown in Figure 2 is an example of a heater having this configuration.

[0028] The number of heaters 15 may be one, or three or more. The heating method of the heater 15 may be an induction heating method that generates heat using an alternating magnetic field, a dielectric heating method that generates heat using a high-frequency electric field, or a laser heating method that generates heat by irradiating atomic motion with a certain amount of light.

[0029] The fuel adhesion surface 121 does not have to be a portion of the inner circumferential surface 12 that is closer to the nozzle hole 32 of the injector 31 than the bottom dead center position BP in the direction of the axis AL of the piston 16. The heater 151 shown in Figure 1 is an example of a heater with this configuration. [Explanation of symbols]

[0030] 1...Internal combustion engine 9...Cylinder block 10...Cylinder liner 11...Water jacket 12...Inner peripheral surface 13...Outer surface

Claims

1. An internal combustion engine having a cylinder block, The cylinder block includes a cylinder liner having an outer peripheral surface; an opposing wall opposing the outer circumferential surface; a water jacket defined by the outer circumferential surface and the opposing wall; a heater accommodated in the water jacket in contact with the outer circumferential surface; An internal combustion engine comprising:

2. a piston housed within the cylinder liner; an injector that injects fuel, The inner peripheral surface of the cylinder liner is a fuel adhesion surface on which the liquid fuel injected from the injector adheres, a contact surface, which is a portion of the outer circumferential surface that comes into contact with the heater, including an opposite surface, which is a portion of the outer circumferential surface that is located on the opposite side of the fuel adhesion surface in the radial direction of the piston.

2. The internal combustion engine according to claim 1.

3. the injector is a direct injection injector that injects fuel toward the inside of the cylinder liner, the fuel adhesion surface is a portion of the inner circumferential surface that is located closer to the nozzle hole of the injector in a direction along the axis of the piston than a top surface of the piston when the piston is located at bottom dead center.

3. The internal combustion engine according to claim 2.

4. When a line segment that is perpendicular to the axis of the piston and that connects the nozzle hole of the injector and the axis is defined as a virtual line segment, and a plane that includes the axis and is perpendicular to the virtual line segment is defined as a first virtual plane, the fuel adhesion surface is one of two semi-cylindrical surfaces obtained by equally dividing the inner circumferential surface by the first imaginary plane, the semi-cylindrical surface being located on the opposite side of the nozzle hole with respect to the axis.

4. The internal combustion engine according to claim 3.

5. When a plane that includes the virtual line segment and is perpendicular to the first virtual plane is defined as a second virtual plane, The contact surface includes an intersection line between the second imaginary plane and the opposite surface.

5. The internal combustion engine according to claim 4.

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