Internal combustion engine

Abstract

To provide an internal combustion engine capable of supplying fuel to an upper part and a lower part of a lip of a piston.SOLUTION: An internal combustion engine includes a cylinder head, a piston and a fuel injection valve for injecting fuel. The piston includes a cavity formed on a top surface of the piston and forming a combustion chamber between the cylinder head and the cavity. The cavity includes: a projecting part that is disposed at a central part of the cavity and projects toward the fuel injection valve; a lip part disposed around the cavity; and a flip-up part that is disposed in the projecting part to splash the fuel toward the lip part.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to internal combustion engines. [Background technology]

[0002] Conventionally, an internal combustion engine equipped with a piston having a cavity has been known (see, for example, Patent Document 1). In the internal combustion engine of Patent Document 1, a protrusion facing a fuel injection valve is disposed on the top surface of the piston, and fuel is caused to impinge on the protrusion. The impinging fuel diffuses into the cavity. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 10-184362 Summary of the Invention [Problem to be solved by the invention]

[0004] The internal combustion engine of Patent Document 1 has a groove in the convex portion for supplying fuel that collides with the convex portion toward the bottom of the cavity. This supplies fuel to the space surrounded by the cavity peripheral wall and bottom wall below the lip of the cavity. Patent Document 1 does not disclose the supply of fuel to the space above the lip.

[0005] An object of the present disclosure is to provide an internal combustion engine in which fuel can be supplied to the upper and lower lips of the piston. [Means for solving the problem]

[0006] The internal combustion engine according to the present disclosure comprises a cylinder head, a piston, and a fuel injection valve that injects fuel, the piston having a cavity formed on the top surface of the piston that forms a combustion chamber between the piston and the cylinder head, the cavity including a convex portion disposed in the center of the cavity and protruding toward the fuel injection valve, a lip portion disposed around the cavity, and a splash-up portion disposed on the convex portion that splashes the fuel toward the lip portion. [Effects of the Invention]

[0007] According to the internal combustion engine of the present disclosure, fuel collides with the lip portion due to the splash-up portion aimed at the lip portion. The fuel that collides with the lip portion forms fuel sprays above and below the lip portion. This allows fuel to be supplied to the upper and lower portions of the piston lip. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram showing an internal combustion engine according to a first embodiment of the present disclosure. [Figure 2] FIG. 2 is a top view of a piston according to a first embodiment of the present disclosure. [Figure 3] FIG. 2 is a diagram showing a diffusion state of fuel according to the first embodiment of the present disclosure. [Figure 4] FIG. 10 is a top view of a piston according to a second embodiment of the present disclosure. [Figure 5] FIG. 10 is a side view of a protrusion according to a second embodiment of the present disclosure. [Figure 6] FIG. 10 is a diagram showing a diffusion state of fuel according to a second embodiment of the present disclosure. [Figure 7] FIG. 10 is a top view of a piston according to a third embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0009] First Embodiment A first embodiment of the present disclosure will be described below with reference to the drawings. In the drawings, the upper side of the internal combustion engine 1 is designated US, the lower side DS, the intake side IN, the exhaust side EX, the front side FS, and the rear side BS. In this embodiment, an example will be described in which a cylinder 21 (described later) is arranged vertically and a piston 6 slides vertically. However, the cylinder 21 may be arranged at an angle relative to the vertical direction, as in a V-type engine, for example. Furthermore, the cylinder 21 may be arranged horizontally, as in a horizontally opposed engine, for example.

[0010] 1, the internal combustion engine 1 includes a cylinder block 2, a cylinder head 4, a piston 6, a plurality of intake valves 8, a plurality of exhaust valves 10, and a fuel injection valve 12. The internal combustion engine 1 of this embodiment is a direct injection diesel engine in which the fuel injection valve 12 directly injects fuel into a cylinder 21 of the cylinder block 2. In this embodiment, two intake valves 8 and two exhaust valves 10 are arranged in one cylinder 21.

[0011] The internal combustion engine 1 may further include a swirl flow generating means. The swirl flow generating means may be, for example, two intake valves 8. In this embodiment, the lift heights of the two intake valves 8 are different, thereby generating a swirl flow in which the intake air swirls along a plane perpendicular to the sliding direction of the piston 6 (in this embodiment, the up-and-down direction). Note that the swirl flow generating means may also be an intake port of the cylinder head 4 shaped to generate a swirl flow. Alternatively, a valve that generates a swirl flow may be provided.

[0012] The piston 6 has a cavity 61 on its top surface. When the piston 6 is at top dead center, the cavity 61 forms a combustion chamber between the piston 6 and the cylinder head 4. Therefore, it is preferable that the air-fuel mixture supplied to the cavity 61 is as homogeneous as possible. In the case of the direct injection diesel engine of this embodiment, it is preferable that the spray of fuel injected into the cavity 61 is diffused to form a homogeneous air-fuel mixture.

[0013] The cavity 61 includes a protrusion 62 , a lip 63 , and a raised portion 64 .

[0014] The protrusion 62 is disposed in the center of the bottom surface 69 of the piston 6. The protrusion 62 protrudes in a conical shape from the bottom surface 69 of the cavity 61 toward the fuel injection valve 12. The lip portion 63 is disposed around the periphery of the cavity 61.

[0015] The lip portion 63 has a lip protrusion 63a, a first lip portion 63b which is a surface extending from the lip protrusion 63a toward the cylinder head, and a second lip portion 63c which is a surface extending from the lip protrusion 63a toward the bottom surface 69 of the cavity 61.

[0016] Lip protrusion 63a extends from piston top surface 66 toward convex portion 62. As shown in FIG. 2, lip protrusion 63a is an annular portion formed along the periphery of piston 6. Lip protrusion 63a is formed with valve recesses 67 that prevent interference between intake valve 8 and exhaust valve 10 and piston 6. Valve recess 67 is formed by circularly recessing lip protrusion 63a toward bottom surface 69 along the valve shape.

[0017] As shown enlarged in FIG. 1, the spring-up portion 64 is disposed on the convex portion 62. The spring-up portion 64 has a sloped surface 64a and a spring-up surface 64b. The sloped surface 64a is a side surface of the conical convex portion 62, and is an inclined surface that slopes from the center of the convex portion 62 toward the spring-up surface 64b. The spring-up surface 64b is formed around the sloped surface 64a (see FIG. 2). The spring-up surface 64b is an inclined surface that rises from the lower end of the sloped surface 64a toward the fuel injection valve 12 and toward the periphery of the convex portion 62. By forming the spring-up surface 64b in this manner, fuel injected from the fuel injection valve 12 is spring-up and splashed upward toward the lip portion 63. In the first embodiment, the upper end of the spring-up surface 64b is located below the tip of the lip protrusion 63a. An extension line of the flip-up surface 64b (see the imaginary line X1 shown by the two-dot chain line in FIG. 1) is formed so as to intersect with the lip protruding portion 63a.

[0018] 1, the fuel injection valve 12 has an injection hole facing the protrusion 62 and injects high-pressure fuel. The fuel injection valve 12 may have multiple injection holes for injecting fuel. In this embodiment, the fuel injection valve 12 has eight injection holes.

[0019] As shown in FIG. 3, when fuel is injected from the fuel injection valve 12 in the internal combustion engine 1 according to the first embodiment, the fuel comes into contact with the sloped surface 64a and flows along the sloped surface 64a while diffusing. The fuel flowing along the sloped surface 64a reaches the splashing surface 64b and is thrown by the splashing surface 64b toward the lip portion 63. The fuel thrown toward the lip portion 63 collides with the lip protrusion 63a, is guided by the first lip portion 63b to space A on the cylinder head side, and is guided by the second lip portion 63c to space B on the cavity side (see dotted hatching in FIG. 3). This forms a homogeneous mixture not only inside the cavity 61 but also outside the cavity 61. This improves combustion.

[0020] Second Embodiment Next, a second embodiment will be described with reference to Figures 4 and 6. In the description of the second embodiment, only the differences from the first embodiment will be described. The internal combustion engine 1 of the second embodiment differs from the first embodiment in that it has a first jump-up portion 264 and a second jump-up portion 265 that jump up in different directions. The other configurations are the same as those of the first embodiment, so descriptions will be omitted.

[0021] As shown in FIG. 4, the cavity 261 includes a first raised portion 264 and a second raised portion 265. The first raised portion 264 has a first sloped surface 264a and a first raised surface 264b. The second raised portion 265 has a second sloped surface 265a and a second raised surface 265b. The first raised portion 264 is disposed in a position facing the valve recess 267. In this embodiment, one first raised portion 264 is disposed on each of the intake side and the exhaust side. The second raised portions 265 are adjacent to the first raised portion 264 and are disposed on each of the front and rear sides.

[0022] As shown in FIG. 5, the first spring-up surface 264b is disposed closer to the cylinder head 4 than the second spring-up surface 265b. The first spring-up surface 264b splashes fuel toward the first lip portion 263b. In this embodiment, the inclination angle α of the first spring-up surface 264b is greater than the inclination angle β of the second spring-up surface 265b. This makes it easier for the fuel splashed by the first spring-up surface 264b to reach the first lip portion 263b. The second slope surface 265a and the second spring-up surface 265b of the second spring-up portion 265 have the same configuration as the slope surface 64a and the spring-up surface 64b in the first embodiment. Therefore, detailed description of the second spring-up surface 265b will be omitted.

[0023] The length L1 of the first upward-raising surface 264b is different from the length L2 of the second upward-raising surface 265b. FIG. 5(a) shows an example in which the length L1 of the first upward-raising surface 264b is shorter than the length L2 of the second upward-raising surface 265b. When the length L1 of the first upward-raising surface 264b is shorter than the length L2 of the second upward-raising surface 265b, the fuel on the first upward-raising surface 264b leaves the first upward-raising surface 264b before the fuel on the second upward-raising surface 265b leaves the first upward-raising surface 264b. This results in less fuel adhering to the first upward-raising surface 264b than to the second upward-raising surface 265b, making it easier to enrich the concentration of fuel supplied to the first lip portion 263b than to the second lip portion 263c (see FIG. 6). As a result, it is easier to enrich the air-fuel ratio of the first lip portion 263b. On the other hand, since the distance to the first lip portion 263b is long, it is difficult for fuel to reach the vicinity of the periphery of the piston 6 on the first lip portion 263b.

[0024] 5(b) shows an example in which the length L1 of the first flip-up surface 264b is longer than the length L2 of the second flip-up surface 265b. When the length L1 of the first flip-up surface 264b is longer than the length L2 of the second flip-up surface 265b, the distance to the first lip portion 263b is shorter, and therefore the fuel is more likely to reach the first lip portion 263b near the periphery of the piston 6. On the other hand, more fuel adheres to the first flip-up surface 264b than to the second flip-up surface 265b, and the concentration of fuel supplied to the first lip portion 263b (see FIG. 6) is more likely to be diluted than to the second lip portion 263c.

[0025] In this way, by making the length L1 of the first flip-up surface 264b and the length L2 of the second flip-up surface 265b different, it is possible to change the fuel concentration in the space A on the cylinder head side of the first lip portion 263b and the space B on the cavity side of the second lip portion 263c, as well as the distance the fuel can reach. For example, if the fuel concentration in the first lip portion 263b on the intake side is likely to be low, the internal combustion engine 1 may make the length L1 of the first flip-up surface 264b on the intake side shorter than the length L2 of the second flip-up surface 265b. For example, if the fuel concentration in the first lip portion 263b on the exhaust side near the periphery of the piston 6 is low, the internal combustion engine 1 may make the length L1 of the first flip-up surface 264b on the exhaust side of the cavity 61 longer than the length L2 of the second flip-up surface 265b. In this way, the internal combustion engine 1 may appropriately change the length L1 of the first upward-moving surface 264b and the length L2 of the second upward-moving surface 265b depending on the fuel concentration around the cavity 61 and the like.

[0026] As shown in FIG. 6, in the internal combustion engine 201 according to the second embodiment, when fuel is injected from the fuel injection valve 212, the fuel contacts the first slope surface 264a and the second slope surface 265a and flows along the first slope surface 264a and the second slope surface 265a while diffusing. The fuel flowing along the first slope surface 264a reaches the first upturned surface 264b and is thrown toward the first lip portion 263b by the upturned surface 264b. The reverse squish flow from the second lip portion 263c toward the first lip portion 263b is weakened in the valve recess 267 (see FIG. 4). Therefore, the amount of fuel that collides with the lip protrusion 263a and flows to the first lip portion 263b is likely to be reduced. However, by arranging the first upturned portion 264 facing the valve recess 267, fuel is easily supplied to the first lip portion 263b. As in the first embodiment, the fuel that flows along the second slope surface 265a reaches the second flip-up surface 265b, and is thrown by the second flip-up surface 265b toward the lip protruding portion 263a.

[0027] <Third embodiment> Next, a third embodiment will be described with reference to FIG. 7. In the description of the third embodiment, only the differences from the first and second embodiments will be described. An internal combustion engine 301 of the third embodiment differs from the first and second embodiments in that a groove 368 is formed in a convex portion 362, and a slope surface 364a and a splash-up surface 364b are formed at the bottom of the groove. The other configurations are the same as those of the first and second embodiments, so description thereof will be omitted.

[0028] 7, cavity 361 of piston 306 has groove 368. Groove 368 is formed by recessing the surface of protrusion 362 toward bottom surface 369. In this embodiment, eight grooves 368 are arranged to match the number of nozzle holes of fuel injection valve 312. Slope surface 364a and bounce-up surface 364b are each arranged on the bottom surface of groove 368.

[0029] The groove 368 curves along the circumferential direction of the convex portion 362. In this embodiment, the portion of the groove 368 near the end of the lip protruding portion 363a of the convex portion 362 curves counterclockwise along the circumferential direction of the convex portion 362. This allows, for example, the fuel spray flying out from the splash-up surface 364b to diffuse along the swirl flow S (see the arrow in FIG. 7). As a result, the fuel is more likely to diffuse.

[0030] As described above, according to the present disclosure, the splash-up portion 64, 364 (the second splash-up portion 265 in the second embodiment) aimed at the lip portion 63, 263, 363 causes fuel to collide with the lip protrusion portion 63a, 263a, 363a. The fuel that collides with the lip protrusion portion 63a, 263a, 363a forms fuel sprays above and below the lip protrusion portion 63a, 263a, 363a. This allows fuel to be supplied to the above and below the lip protrusion portion 63a, 263a, 363a.

[0031] <Other embodiments> Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above embodiments, and various modifications are possible within the scope of the gist of the invention. In particular, the multiple modifications described in this specification can be arbitrarily combined as necessary.

[0032] (a) In the second embodiment described above, an example was described in which one first flip-up portion 264 is disposed on each of the intake side and the exhaust side, but the present disclosure is not limited to this. For example, the first flip-up portion 264 on the exhaust side may be divided into two, with the second flip-up portion 265 disposed between them. In any case, the first flip-up portion 264 may be disposed in any manner as long as it is disposed in a position facing the valve recess 267.

[0033] (b) In the third embodiment, the grooves 368 are bent in the rotational direction of the swirl flow S along the circumferential direction of the protrusion 362, but the present disclosure is not limited to this. The grooves 368 may be bent in the counter-rotational direction of the swirl flow S. In this case, the fuel spray flying out from the splash-up surface 364b collides with the swirl flow S and is diffused. [Explanation of symbols]

[0034] 1,201,301: Internal combustion engine 4: Cylinder head 6 206 306: Piston 8: Intake valve, 10: Exhaust valve 12,212: Fuel injection valve 21: Cylinder 64: Flip-up section, 264: First flip-up section, 265: Second flip-up section 61: Cavity 62, 262, 362: Convex part, 63, 263, 363: Lip part 63a, 263a, 363a: Lip protrusion 63b, 263b: First lip 63c, 263c: Second lip 64a, 364a: Slope surface 264a: First slope surface, 265a: Second slope surface 64b, 364b: Flip-up surface 264b: First flip-up surface, 256b: Second flip-up surface 66: Piston top 67,267: Valve recess 69,269,369: Bottom

Claims

1. A cylinder head, The piston and a fuel injection valve that injects fuel; Equipped with The piston has a cavity formed on a top surface of the piston, the cavity forming a combustion chamber between the piston and the cylinder head, The cavity is a protrusion disposed in a central portion of the cavity and protruding toward the fuel injection valve; a lip portion disposed around the cavity; a splash-up portion disposed on the protruding portion and splashing the fuel toward the lip portion; Including, Internal combustion engine.

2. The lip portion is a lip protrusion extending toward the convex portion; a first lip portion extending from the lip protruding portion toward the cylinder head; a second lip portion extending from the lip protrusion portion toward the cavity; and The flip-up portion is a first splash-up portion that splashes the fuel toward the first lip portion; a second splash-up portion that splashes the fuel toward the second lip portion; having 2. The internal combustion engine according to claim 1.

3. the cylinder head has a valve; the cavity has a valve recess that is disposed on the cylinder head side of the lip protrusion and is recessed along the valve; The first pop-up portion is disposed opposite the valve recess, The second pop-up portion is disposed opposite to the valve recess at a different position.

3. The internal combustion engine according to claim 2.

4. The spring-up portion has a slope surface and a spring-up surface, The first flip-up portion and the second flip-up portion have different lengths of the flip-up surfaces.

3. The internal combustion engine according to claim 2.

5. a groove is disposed in the convex portion, the raised portion is disposed in the groove, and the groove is curved along the circumferential direction of the convex portion; 5. An internal combustion engine according to any one of claims 1 to 4.

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