Internal combustion engine

Abstract

To provide an auxiliary chamber type internal combustion engine that can acquire a stable combustion state of a main combustion chamber.SOLUTION: An internal combustion engine includes: a main combustion chamber 5 including a cylinder head 2 and a piston 4; and an auxiliary chamber 6 installed in the main combustion chamber 5. The auxiliary chamber 6 is configured to be supported by the cylinder head 2 so as to be rotatable about an axis that extends along a direction of movement of the piston 4.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] This invention relates to an internal combustion engine.

Background Art

[0002] In a prechamber type internal combustion engine having a prechamber provided in the main combustion chamber, an air-fuel mixture of fuel and intake air is supplied into the prechamber, and the air-fuel mixture is ignited in the prechamber by a spark plug. When a flame is formed in the prechamber, the flame is injected into the main combustion chamber through a plurality of injection holes formed in the prechamber. Then, the air-fuel mixture in the main combustion chamber is ignited by the plurality of injected flames. Thereby, a good combustion state in the main combustion chamber is realized (for example, refer to Patent Document 1 below).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In an internal combustion engine in which a plurality of injection holes are formed in the prechamber, the flame propagations injected from each injection hole may collide with each other, and combustion accompanied by a shock similar to knocking (hereinafter referred to as jet shock) may occur. This jet shock is more likely to be remarkable when the air-fuel ratio of the air-fuel mixture is stoichiometric than when it is lean, because the amount of fuel that burns and spreads is larger. Further, this jet shock and knocking are likely to be confused, which may cause a problem in terms of knock sensing performance. In particular, in a passive type prechamber type internal combustion engine in which an air-fuel mixture mixed in the intake passage or the main combustion chamber is introduced into the prechamber, cycle variation in which the size of the flame injected from each injection hole varies every combustion cycle is likely to occur, which may cause a problem in terms of uniform ignition of the air-fuel mixture in the main combustion chamber.

[0005] Therefore, the objective of this invention is to obtain a stable combustion state in the main combustion chamber of a sub-chamber type internal combustion engine. [Means for solving the problem]

[0006] In order to solve the above problems, this invention provides: A main combustion chamber comprising a cylinder head and piston, A sub-chamber provided within the main combustion chamber, The internal combustion engine is configured such that the sub-chamber is rotatably supported by the cylinder head around the axis of a shaft extending in the direction of movement of the piston.

[0007] In the above configuration, Preferably, the sub-chamber has a main body having an outer surface facing the main combustion chamber and an inner surface facing the opposite side of the outer surface, and a nozzle is formed at a position radially outward from the center of the axis of the main body, penetrating the inner and outer surfaces of the main body and inclined at least in the circumferential direction with respect to the radial direction, and the sub-chamber is configured to rotate due to the outward injection pressure from the nozzle.

[0008] In all of the above configurations, Preferably, the sub-chamber has a flange portion extending radially outward, and the cylinder head has a clamping portion that rotatably supports the flange portion and an oil reservoir portion in which oil is stored and a part of the flange portion is immersed.

[0009] In the configuration having the flange portion, Preferably, a projection is formed around the periphery of the flange portion, extending axially and acting as a barrier to the radially outward flow of oil.

[0010] In the configuration having the flange portion, Preferably, the flange portion is provided with a supply unit for supplying oil to the oil reservoir and a discharge unit for discharging oil from the oil reservoir, and with a plurality of fins that stand upright in the axial direction spaced apart in the circumferential direction.

[0011] In all of the above configurations, It is preferable to provide a permanent magnet in the sub-chamber and an electromagnet in the cylinder head, and to configure the system so that rotational force is applied to the sub-chamber by energizing the electromagnet. [Effects of the Invention]

[0012] In this invention, in a pre-chamber type internal combustion engine, the pre-chamber is made rotatable around an axis extending in the direction of piston movement, and flames are ejected while it is rotating. This suppresses abnormal combustion accompanied by shocks caused by the collision of flame propagations, and also equalizes the cycle fluctuations in the size of the flames ejected from each nozzle, thereby achieving a stable combustion state in the main combustion chamber. [Brief explanation of the drawing]

[0013] [Figure 1] This is a cross-sectional view showing the main part of the first embodiment of the internal combustion engine according to this invention. [Figure 2] Figure 1 is a cross-sectional view of a sub-chamber used in an internal combustion engine. [Figure 3] Figure 1 is a perspective view of a sub-chamber used in an internal combustion engine. [Figure 4] This is a cross-sectional view showing the main part of a second embodiment of an internal combustion engine according to the present invention. [Figure 5] Figure 4 is a cross-sectional view of a sub-chamber used in an internal combustion engine. [Figure 6] Figure 4 is a perspective view of a sub-chamber used in an internal combustion engine. [Figure 7] This is a schematic cross-sectional view showing the main part of the third embodiment of the internal combustion engine according to this invention. [Figure 8] Figure 7 is a cross-sectional view of a sub-chamber used in an internal combustion engine. [Figure 9] It is a perspective view of a sub-chamber used in the internal combustion engine shown in FIG. 7.

Embodiment for Carrying Out the Invention

[0014] A first embodiment of an internal combustion engine 1 according to this invention will be described based on the drawings. As shown in FIG. 1, this internal combustion engine 1 is a sub-chamber type internal combustion engine 1 (gasoline engine) having a main combustion chamber 5 equipped with a piston 4 that reciprocates within a cylinder head 2 and a cylinder block 3, and a sub-chamber 6 provided within the main combustion chamber 5 as main components. Note that this figure shows the main part of one cylinder out of a plurality of cylinders of the internal combustion engine 1. Also, in this figure, only the members directly related to this invention are shown, and descriptions of general configurations such as an intake passage for sending air into the main combustion chamber 5, an exhaust passage for exhausting combustion gases from the main combustion chamber 5, and an injection device for supplying fuel to the main combustion chamber 5 are omitted. In this embodiment, the internal combustion engine 1 has an injection device in the intake passage and mixes intake air and fuel within the intake passage and the main combustion chamber 5, but it is not limited to this configuration.

[0015] The cylinder head 2 is composed of a lower head 7 and an upper head 8 arranged corresponding to the positions of each cylinder. On the upper surface side of the lower head 7, cylindrical recesses 9 having female screw portions on their inner surfaces are formed corresponding to the positions of each cylinder. A through hole 10 communicating with the main combustion chamber 5 side is formed on the bottom surface of this recess 9. A male screw portion is formed on the outer periphery of the upper head 8, and by screwing this upper head 8 into the lower head 7, the lower head 7 and the upper head 8 are integrated. A washer made of, for example, copper is provided as a seal member 11 between the lower head 7 and the upper head 8.

[0016] In the axial center of the upper head 8, a cavity is formed upward from its bottom surface, and a spark plug 12 is provided so as to face the inside of this cavity. On the bottom surface of the recess 9 formed in the lower head 7 and on the lower surface of the upper head 8, one annular groove 13, 14 and two seal grooves 15, 16 are concentrically formed in order from the outer diameter side to the inner diameter side. Incidentally, the upper head 8 and the spark plug 12 may be integrally formed.

[0017] As shown in FIGS. 1 to 3, the auxiliary chamber 6 has a main body portion 17 having an outer surface facing the main combustion chamber and an inner surface facing the side opposite to the outer surface, and a flange portion 18 extending radially outward from the upper end outer edge of the main body portion 17. The main body portion 17 is a bottomed cylindrical shape that opens upward, and at a position radially outward from the axis of the main body portion 17 (a line passing through the center of the main body portion 17 and extending (in the vertical direction) toward the cylinder head 2 and the piston 4), a plurality of injection holes 19 penetrating the inner and outer surfaces of the main body portion 17 and inclined downward in the axial direction on one side in the circumferential direction (the direction of rotation around the axis) with respect to the radial direction (the direction orthogonal to the direction in which the axis extends (hereinafter referred to as the "axial direction")) are formed. Since the injection holes 19 are inclined on one side in the circumferential direction with respect to the radial direction, the auxiliary chamber 6 is configured to rotate by the outward flame injection pressure from the injection holes 19. The lower end of the main body portion 17 and the injection holes 19 project toward the main combustion chamber 5 side through the through hole 10 formed in the lower head 7. The outer surface of the main body portion 17 is subjected to mirror finishing.

[0018] In this embodiment, the injection holes 19 are configured to be inclined downward in the axial direction on one side in the circumferential direction with respect to the radial direction. However, as long as they are inclined on at least one side in the circumferential direction, the rotational action of the auxiliary chamber 6 due to the flame injection pressure from the injection holes 19 is exhibited.

[0019] Seal grooves 20 are formed on the upper and lower surfaces of the flange portion 18 so as to face the seal grooves 15 and 16 formed in the lower head 7 and upper head 8, respectively. Multiple fins 21 are provided at regular intervals in the circumferential direction on the peripheral edge of the flange portion 18, formed by increasing the axial width (vertical width in this embodiment) of the flange portion 18. In addition, multiple oil holes 22 are provided at regular intervals in the circumferential direction, penetrating the upper and lower surfaces of the flange portion 18.

[0020] The flange portion 18 is rotatably supported from above and below by a clamping portion 23 formed in the cylinder head 2. The clamping portion 23 is formed between the bottom surface of a recess 9 formed in the lower head 7 and the bottom surface of the upper head 8. At this time, the sub-chamber combustion chamber 24 is formed by the internal space of the main body portion 17 of the sub-chamber 6 and the cavity formed in the upper head 8.

[0021] An annular oil reservoir 25 is formed by annular grooves 13 and 14 formed in the integrated lower head 7 and upper head 8, respectively, and lubricating oil is introduced into this oil reservoir 25. The fins 21 formed on the periphery of the flange portion 18 are located within the oil reservoir 25 and are immersed in the oil.

[0022] The oil reservoir 25 is connected to a supply unit 26 that supplies oil from an oil gallery (not shown) to the oil reservoir 25, and a discharge unit 27 that returns oil from the oil reservoir 25 to the oil gallery. The oil in the oil reservoir 25 is pumped by the drive of an oil pump (not shown).

[0023] Two seal rings 28 are concentrically provided between the seal grooves 15 and 20 formed on the bottom surface of the recess in the lower head 7 and the lower surface of the flange portion 18, and between the seal grooves 16 and 20 formed on the lower surface of the upper head 8 and the upper surface of the flange portion 18. By providing these seal rings 28, it is prevented that oil from the oil reservoir 25 leaks out to the main body portion 17 through the gap between the cylinder head 2 (lower head 7, upper head 8) and the flange portion 18, and the pressure due to the combustion of the fuel-air mixture in the main combustion chamber 5 and sub-chamber 6 acts on the oil reservoir 25. The number of seal rings 28 can be increased or decreased as appropriate, as long as the function of the seal rings 28 is fully performed.

[0024] The vertical pressing force applied to the flange portion 18 by the clamping portion 23 of the cylinder head 2 is appropriately set to a magnitude that ensures sealing performance by the seal ring 28 without hindering the smooth rotation of the sub-chamber 6.

[0025] The angular velocity ω of the rotation of the sub-chamber 6 due to the reaction of the flame ejection from the nozzle 19 can be calculated by the following equation (1). Here, Q is the combustion pressure injection amount at the time of ignition in the sub-chamber combustion chamber 24, R is the radial distance from the central axis to the tip of the nozzle 19, A is the cross-sectional area of ​​each nozzle 19, θ is the angle that the injection direction makes with the radial direction, and a is a coefficient determined by the frictional force acting on the sub-chamber 6 during rotation. The combustion pressure injection amount Q is appropriately considered based on the volume of each cylinder, etc. Note that this equation (1) is applicable when two nozzles 19 are formed at circumferentially opposing positions on the sub-chamber 6. By using this equation, the specifications of the sub-chamber 6, such as the radial distance R from the central axis to the tip of the nozzle 19, the cross-sectional area A of each nozzle 19, and the angle θ that the injection direction makes with the radial direction, can be determined in order to obtain the desired angular velocity ω. ω = (aQ / 2RA) × sinθ (1)

[0026] In the internal combustion engine 1 described above, the sub-chamber 6 is rotatably supported by the cylinder head 2 around an axis extending in the direction of movement of the piston 4, and the sub-chamber 6 is configured to rotate due to the outward flame injection pressure from the nozzles 19. As a result, during the combustion stroke, the flame injected from one nozzle 19 spreads throughout the entire circumferential direction of the main combustion chamber 5. Therefore, even if there is a difference in the size of the flames injected from each nozzle 19, uneven combustion of the fuel in the main combustion chamber 5 can be suppressed. Furthermore, this rotation can suppress jet shock caused by the collision of flame propagations injected from each nozzle 19.

[0027] Furthermore, during the intake compression process, the inertial rotation accompanying the injection of the flame pushes the mixture of intake air and fuel, which has been mixed in the intake passage and main combustion chamber 5, into the sub-chamber 6. This creates turbulence within the sub-chamber 6, improving premixing and scavenging within the sub-chamber 6.

[0028] In the internal combustion engine 1 described above, the sub-chamber 6 has fins 21 formed on the periphery of the flange portion 18, so that the rotation of the fins 21 can assist in the discharge of oil from the discharge portion 27. Furthermore, when the rotation of the sub-chamber 6 due to flame injection becomes excessive, the rotation of the sub-chamber 6 can be weakened by increasing the oil pumping force, thereby providing rotational resistance to the fins 21.

[0029] Furthermore, while a downward pressure acts on the sub-chamber 6 due to combustion in the sub-chamber combustion chamber 24, an upward pressure acts on it due to combustion in the main combustion chamber 5. When these pressures act, there is a risk that the sub-chamber 6 may move vertically or tilt axially. However, because the peripheral edge (fins 21) of the flange portion 18 is immersed in oil, it functions as a damper, suppressing the movement and tilting of the sub-chamber 6. In addition, because the fins 21 are immersed in oil, heat from the sub-chamber 6 can be quickly dissipated into the oil. Moreover, since multiple oil holes 22 are formed in the flange portion 18 of the sub-chamber 6, penetrating its upper and lower surfaces, the flow of oil between the upper and lower surfaces can be promoted. Furthermore, foreign matter such as shavings generated as the sub-chamber 6 rotates can be smoothly removed by the flow of oil.

[0030] Figure 4 shows a second embodiment of the internal combustion engine 1 according to this invention. The internal combustion engine 1 according to the second embodiment has the same basic configuration as the internal combustion engine 1 according to the first embodiment, but the configuration of the sub-chamber 6 is different. That is, as shown in Figures 4 to 6, instead of forming fins 21 on the peripheral edge of the upper surface of the flange portion 18 of the sub-chamber 6, an annular projection 29 is formed along the entire circumference in the circumferential direction, which stands upright in the axial direction and acts as a barrier to the radially outward flow of oil.

[0031] By forming the protrusion 29 in this manner, when the sub-chamber 6 rotates, the oil is retained inside the protrusion 29, and the centrifugal force prevents the oil from accumulating on the side wall (end wall) of the oil reservoir 25, thus preventing loss of lubrication and fluidity. This ensures smooth rotation of the sub-chamber 6. In this embodiment, fins 21 are formed on the lower surface of the flange portion 18. Since the supply portion 26 and the discharge portion 27 are connected to the oil reservoir 25 below the flange portion 18, it is preferable to provide fins 21 on the lower surface of the flange portion 18 to promote oil circulation.

[0032] In this embodiment, the protruding portion 29 is positioned to rise from the peripheral edge of the upper surface of the flange portion 18 toward the upper head 8, but this direction is not limited. It may also be positioned toward the opposite side of the upper head 8, or it may be positioned toward both the direction toward the upper head 8 and the opposite side.

[0033] Figure 7 shows a third embodiment of the internal combustion engine 1 according to this invention. The internal combustion engine 1 according to the third embodiment is configured to provide rotational force to the sub-chamber 6 by the action of an electromagnet, in addition to the rotational force due to the reaction of flame ejection from the nozzle 19, as in the internal combustion engine 1 according to the first and second embodiments. Although the oil reservoir 25 is not shown in Figure 7, an oil reservoir 25 may also be provided in this embodiment.

[0034] As shown in Figures 7 to 9, the flange portion 18 has multiple rotors 30 (e.g., permanent magnets) arranged at regular intervals in the circumferential direction, and the cylinder head 2 has a stator 31 (e.g., an electromagnet) positioned radially opposite to the rotors 30. Rotational force is applied to the sub-chamber 6 by energizing the stator 31. The cylinder head 2 is also equipped with a Hall sensor 32 facing the flange portion 18, and by detecting the rotation of the rotors 30 with this Hall sensor 32, the angular velocity ω' of the sub-chamber 6 can be measured.

[0035] In this way, by enabling the sub-chamber 6 to be subjected to rotational force by the action of an electromagnet, the rotation of the sub-chamber 6 can be controlled more precisely than in the first and second embodiments.

[0036] In this embodiment, as in the first and second embodiments, the nozzles 19 are configured to be inclined circumferentially with respect to the radial direction. However, since the electromagnet alone can provide rotational force to the sub-chamber 6, the nozzles 19 can also be configured not to be inclined circumferentially.

[0037] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. Accordingly, the scope of the invention is indicated by the claims rather than by the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of symbols]

[0038] 1. Internal combustion engine 2 Cylinder heads 3 Cylinder block 4 pistons 5. Main combustion chamber 6 Antechamber 7 Lower Head 8 Upper head 9 recesses 10 Through holes 11. Sealing member 12 Spark plugs 13, 14 Ring groove 15, 16 Seal groove 17 Main body 18 Flange section 19 nozzles 20 seal grooves 21 fins 22 oil holes 23 Clamping part 24 Sub-chamber combustion chamber 25 Oil reservoir 26 Supply section 27 Discharge section 28 sealing rings 29 Protrusion 30 rotors 31 Stator 32 Hall sensors ω (calculated) angular velocity ω' Actual angular velocity

Claims

1. A main combustion chamber comprising a cylinder head and piston, A sub-chamber provided within the main combustion chamber, The sub-chamber is rotatably supported by the cylinder head around the axis of a shaft extending in the direction of movement of the piston, An internal combustion engine wherein the sub-chamber has a main body having an outer surface facing the main combustion chamber and an inner surface facing the opposite side of the outer surface, and an injection hole is formed at a position radially outward from the center of the axis of the main body, penetrating the inner and outer surfaces of the main body and inclined at least in the circumferential direction with respect to the radial direction, and the sub-chamber is configured to rotate due to the outward injection pressure from the injection hole.

2. The internal combustion engine according to claim 1, wherein the sub-chamber has a flange portion extending radially outward, and the cylinder head has a clamping portion that rotatably supports the flange portion and an oil reservoir portion in which oil is stored and a part of the flange portion is immersed.

3. The internal combustion engine according to claim 2, wherein a projection is formed circumferentially on the peripheral edge of the flange portion, which stands upright in the axial direction and acts as a barrier to the radially outward flow of oil.

4. The internal combustion engine according to claim 2, further comprising a supply unit for supplying oil to the oil reservoir and a discharge unit for discharging oil from the oil reservoir, wherein a plurality of fins that stand upright in the axial direction are provided on the flange at intervals in the circumferential direction.

5. The internal combustion engine according to claim 1, comprising a permanent magnet provided in the sub-chamber and an electromagnet provided in the cylinder head, wherein rotational force is applied to the sub-chamber by energizing the electromagnet.

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