WO2017169533A1

WO2017169533A1 - Internal combustion engine

Info

Publication number: WO2017169533A1
Application number: PCT/JP2017/008706
Authority: WO
Inventors: 雅文瀧; 雅也浅田
Original assignee: 本田技研工業株式会社
Priority date: 2016-03-30
Filing date: 2017-03-06
Publication date: 2017-10-05
Also published as: DE112017001678T5; JP6710749B2; JPWO2017169533A1

Abstract

Provided is an internal combustion engine comprising: a cylinder head (16); a fuel injection device (38) having an injection opening (45) which faces a combustion chamber (22) and injects fuel; and a resin cap (56) inserted in a mounting hole (54) in the cylinder head (16) and having defined therein a through-hole (57) for accommodating the fuel injection device (38). The provided internal combustion engine is configured to contribute to a reduction in the number of parts and to reduce as much as possible the influence of heat.

Description

Internal combustion engine

The present invention relates to an internal combustion engine.

Patent Document 1 discloses a direct injection diesel internal combustion engine. The internal combustion engine includes an injector attached to the cylinder head. The injector nozzle faces the combustion chamber.

Japanese Unexamined Patent Publication No. 2005-307775

The injector is easily affected by the heat of the cylinder head because it is wrapped in the cylinder head. Since the cylinder head is cooled by water cooling, the structure is complicated and the number of parts increases.

An object of the present invention is to provide an internal combustion engine that can suppress the influence of heat as much as possible while contributing to a reduction in the number of parts.

According to the first aspect of the present invention, a cylinder block that defines a cylinder bore that guides the sliding movement of the piston, and the cylinder block that is coupled to the cylinder block to close the cylinder bore and defines a combustion chamber between the piston and the piston. A cylinder head, a fuel injection device having an injection port for injecting fuel facing the combustion chamber, a through hole inserted into the mounting hole of the cylinder head and receiving the fuel injection device, and a heat of the cylinder head An internal combustion engine comprising a low thermal conductivity material guide having a thermal conductivity lower than the conductivity is provided.

According to the second aspect, in addition to the configuration of the first side, the low thermal conductive material guide is a resin body.

According to the third aspect, in addition to the configuration of the first or second aspect, the internal combustion engine is air-cooled.

According to the fourth aspect, in addition to the configuration of any one of the first to third aspects, the internal combustion engine includes a metal shielding wall that partitions the low thermal conductive material guide and the combustion chamber.

According to the fifth aspect, in addition to the configuration of the fourth side surface, the shielding wall is fixed to the tip of the low heat conductive material guide.

According to the sixth aspect, in addition to the configuration of any one of the first to fifth aspects, the low thermal conductive material guide includes a seat surface partitioned by an outer surface of the cylinder head around the attachment hole, and the fuel A large-diameter portion is formed between the step surface formed on the injection device and facing the seat surface.

According to the seventh aspect, in addition to the configuration of any one of the first to sixth side surfaces, the fuel injection device includes a cylindrical nozzle positioned in the attachment hole that defines a cylindrical space, and an outer surface of the nozzle. And an annular seal portion that continues in the circumferential direction.

According to the first aspect, since the low thermal conductive material guide is composed of a member having a thermal conductivity lower than that of the adjacent cylinder head, the heat transmitted to the fuel injection device is reduced. Since the low heat conductive material guide is interposed between the cylinder head and the fuel injection device, heat transfer from the cylinder head toward the fuel injection device is reduced. Therefore, the high temperature of the fuel injection device is suppressed.

According to the second aspect, since the low thermal conductive material guide is formed from a resin material, it can be easily formed.

According to the third aspect, even in an air-cooled internal combustion engine, heat transfer is relaxed from the cylinder head toward the fuel injection device.

According to the fourth aspect, since the low thermal conductive material guide is separated from the combustion chamber by the metal shielding wall, the low thermal conductive material guide can be protected from the heat generated in the combustion chamber.

According to the fifth aspect, since the shielding wall is fixed to the tip of the low thermal conductive material guide as compared with the case where the shielding wall is formed on the cylinder head, the shielding wall is free according to the insertion degree of the low thermal conductive material guide. Can be displaced. Therefore, the position accuracy of the shielding wall can be relaxed. Therefore, the processing cost can be reduced.

According to the sixth aspect, when the fuel injection device is inserted into the mounting hole, the large diameter portion is sandwiched between the outer surface of the cylinder head and the fuel injection device, and the large diameter portion is pressed against the cylinder head to reduce heat. The conductive material guide can be fixed to the cylinder head. The low heat conductive material guide does not have to be fixed by its own fixing means. The fixing of the low heat conductive material guide is simplified.

According to the seventh aspect, when the nozzle is inserted into the mounting hole, the distance between the outer surface of the nozzle and the inner surface of the mounting hole is reduced at the seal portion. Accordingly, the low thermal conductive material guide is in close contact with the outer surface of the nozzle and the inner surface of the mounting hole, particularly at the seal portion. Thus, the seal portion realizes an oil seal function. The low heat conductive material guide can reduce heat transmitted from the cylinder head to the seal portion.

FIG. 1 is a sectional view schematically showing the structure of an internal combustion engine. (First embodiment) FIG. 2 is an enlarged partial sectional view schematically showing the configuration of the spark plug and the fuel injection device. (First embodiment)

DESCRIPTION OF SYMBOLS 11 ... Internal combustion engine 15 ... Cylinder block 16 ... Cylinder head 18 ... Piston 19 ... Cylinder bore 22 ... Combustion chamber 38 ... Fuel injection device (injector)
44 ... Nozzle 45 ... Injection port 46 ... Step surface 54 ... Mounting hole 55 ... Seat surface 56 ... Low heat conductive material guide (resin cap)
57 ... Through-hole 58 ... Shielding wall 59 ... Large diameter part 61 ... Seal part

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

First embodiment

FIG. 1 shows an overall image of an internal combustion engine 11 according to an embodiment of the present invention. An engine body 12 of the internal combustion engine 11 includes a crankcase 14 that supports a crankshaft 13 so as to be rotatable about a rotation axis Xis, a cylinder block 15 that is coupled to the crankcase 14, and a cylinder head 16 that is coupled to the cylinder block 15. And a head cover 17 coupled to the cylinder head 16. A cylinder bore 19 that guides the sliding movement of the piston 18 is defined in the cylinder block 15. A crankshaft 13 is connected to the piston 18 by a connecting rod 21. The axial movement of the piston 18 is converted into the rotational movement of the crankshaft 13. The cylinder head 16 closes the cylinder bore 19 and defines a combustion chamber 22 between the cylinder head 16 and the piston 18. For example, when the internal combustion engine 11 is mounted on a saddle-ride type vehicle such as a motorcycle, the rotation axis Xis of the crankshaft 13 is arranged in parallel to the rear wheel axle.

The internal combustion engine 11 is configured to be air-cooled. The cylinder block 15 has a plurality of heat radiation fins 23 that spread outward from the outer surface thereof. The heat transmitted to the cylinder block 15 is radiated from the radiation fins 23 to the atmosphere. The cylinder block 15 and the cylinder head 16 are molded from, for example, an aluminum alloy.

In the cylinder head 16, an intake port 24 and an exhaust port 25 are defined. The intake port 24 and the exhaust port 25 are opened in the combustion chamber 22. An intake valve 26 that opens and closes the intake port 25 is supported on the cylinder head 16. Similarly, an exhaust valve 27 that opens and closes the exhaust port 25 is supported on the cylinder head 16. An elastic force is applied to the intake valve 26 and the exhaust valve 27 from the spring in a direction to close the intake port 24 and the exhaust port 25, respectively.

Between the cylinder head 16 and the head cover 17, a valve operating mechanism 28 connected to the intake valve 26 and the exhaust valve 27 is accommodated. The valve operating mechanism 28 includes an intake-side rocker arm 31 and an exhaust-side rocker arm 32 that are individually swingably supported by

rocker shafts

29a and 29b. The intake-side rocker arm 31 is pressed against the valve shaft of the intake valve 26 at one end and contacts the intake cam 33 at the other end. The exhaust-side rocker arm 32 is pressed against the valve shaft of the exhaust valve 27 at one end and contacts the exhaust cam 34 at the other end. The intake cam 33 and the exhaust cam 34 are formed on a camshaft 35 having an axis parallel to the axis of the

rocker shafts

29a and 29b. The axis of the camshaft 35 is arranged in parallel to the rotation axis of the crankshaft 13. The rotational force of the crankshaft 13 is transmitted to the camshaft 35 via a transmission mechanism (not shown). The opening / closing operations of the intake valve 26 and the exhaust valve 27 are controlled according to the rotation operation of the camshaft 35.

As shown in FIG. 2, a spark plug 37 and an injector 38 as a fuel injection device are attached to the cylinder head 16. The spark plug 37 is fitted into the plug hole 39 of the cylinder head 16. The tip of the spark plug 37 faces the combustion chamber 22. The spark plug 37 ignites the air-fuel mixture compressed in the combustion chamber 22.

The injector 38 includes an injector body 43 that supports the connection pipe 41 and the coupler 42, and a nozzle 44 that extends from the injector body 43 and has a smaller diameter than the injector body 43. The injector 38 has an injection port 45 that is disposed at the tip of the nozzle 44 and injects fuel toward the combustion chamber 22. The injector body 43 is partitioned with a step surface 46 that faces the outer surface of the cylinder head 16 while surrounding the nozzle 44.

The injector holder 47 is coupled to the connecting pipe 41. The connection pipe 41 is fitted into the supply port 49 via an O-ring 48, for example. In this way, the injector 38 is attached to the injector holder 47. The injector holder 47 includes a mounting piece 52 that is superimposed on a boss 51 formed on the outer surface of the cylinder head 16. The injector holder 47 is bolted to the cylinder head 16 with a mounting piece 52. In this way, the injector holder 47 is fixed to the cylinder head 16.

The fuel pipe (not shown) connected to the fuel pump is connected to the injector holder 47. Fuel is supplied from the fuel pump to the injector 38 at a specified pressure. A control line is connected to the coupler 42 from an electronic control device (not shown). The electronic control device supplies a control signal specifying the operation of the injector 38 to the injector 38.

An attachment hole 54 is formed in the cylinder head 16. The attachment hole 54 passes through the cylinder head 16. The tip of the attachment hole 54 opens in the combustion chamber 22. The attachment hole 54 defines a cylindrical space. On the outer surface of the cylinder head 16, a seat surface 55 is formed that surrounds the attachment hole 54 around the attachment hole 54 and is partitioned by a plane orthogonal to the central axis of the attachment hole 54. The step surface 46 faces the seat surface 55.

A resin cap 56 as a low heat conductive material guide is inserted into the mounting hole 54. The resin cap 56 defines a through hole 57 that receives the injector 38. The nozzle 44 is inserted into the through hole 57 in the attachment hole 54. A resin cap 56 is interposed between the nozzle 44 and the cylinder head 16 over the entire circumference around the central axis of the nozzle 44. Since the resin cap 56 is configured as a member having a thermal conductivity lower than that of the adjacent cylinder head 16, the heat transmitted to the injector 38 is reduced.

The resin cap 56 may be made of a material having a lower thermal conductivity than the material of the cylinder head 16 even if it is other than resin. In the present embodiment, the cylinder head 16 is made of aluminum having a lighter specific gravity than iron. In this case, the low thermal conductive material guide is in addition to a resin material or ceramic having a lower thermal conductivity than aluminum, It may be formed of molybdenum or cobalt which is a sintered body.

A shielding wall 58 is fixed to the tip of the resin cap 56. The shielding wall 58 is made of a metal or other material having heat resistance. The shielding wall 58 partitions the resin cap 56 and the combustion chamber 22.

The resin cap 56 includes a large-diameter portion 59 sandwiched between the seat surface 55 of the cylinder head 16 and the stepped surface 46 of the injector 38. The large diameter portion 59 is pressed against the cylinder head 16. The pressing of the large-diameter portion 59 is held by the action of the injector holder 47.

The injector 38 has an annular seal portion 61 that protrudes from the outer surface of the nozzle 44 and continues in the circumferential direction at a position away from the shielding wall 58 in the axial direction. The space between the outer surface of the nozzle 44 and the inner surface of the mounting hole 54 is narrowed by the seal portion 61. In particular, the resin cap 56 is in close contact with the outer surface of the nozzle 44 and the inner surface of the mounting hole 54 at the seal portion 61.

In the internal combustion engine 11, the resin cap 56 is inserted into the mounting hole 54 of the cylinder head 16, and the nozzle 44 of the injector 38 is received in the through hole 57 of the resin cap 56. Since the resin cap 56 is interposed between the cylinder head 16 and the nozzle 44, heat transfer from the cylinder head 16 toward the nozzle 44 is reduced. Therefore, the high temperature of the nozzle 44 is suppressed.

The internal combustion engine 11 is configured to be air-cooled. Radiation fins 23 are formed in the cylinder block 15. Even in such an air-cooled internal combustion engine 11, heat transfer is relaxed from the cylinder head 16 toward the nozzle 44.

In the present embodiment, the shielding wall 58 partitions the resin cap 56 and the combustion chamber 22. The resin cap 56 can be protected from the heat generated in the combustion chamber 22. In particular, since the shielding wall 58 is fixed to the tip of the resin cap 56, the shielding wall 58 can be freely displaced according to how the resin cap 56 is inserted. Therefore, the positional accuracy of the shielding wall 58 can be relaxed. On the other hand, if the shielding wall 58 is formed on the cylinder head 16, the degree of insertion of the resin cap 56 is determined according to the position of the shielding wall 58, and thus high positional accuracy is required for the shielding wall 58. . The difficulty of processing increases and the processing cost increases.

The large diameter portion 59 of the resin cap 56 is sandwiched between the seat surface 55 defined on the outer surface of the cylinder head 16 and the step surface 46 formed on the injector 38. When the injector 38 is inserted into the mounting hole 54, the large diameter portion 59 is sandwiched between the outer surface of the cylinder head 16 and the injector 38, and the large diameter portion 59 is pressed against the cylinder head 16, so that the resin cap 56 is a cylinder. It is fixed to the head 16. The resin cap 56 does not have to be fixed by its own fixing means. Fixing of the resin cap 56 is simplified.

When the nozzle 44 is inserted into the mounting hole 54, the gap between the outer surface of the nozzle 44 and the inner surface of the mounting hole 54 is narrowed by the seal portion 61. Therefore, the resin cap 56 is in close contact with the outer surface of the nozzle 44 and the inner surface of the mounting hole 54, particularly at the seal portion 61. Thus, the resin cap 56 realizes an oil seal function around the seal portion 61. The resin cap 56 can reduce heat transmitted from the cylinder head 16 to the seal portion 61.

Claims

A cylinder block (15) defining a cylinder bore (19) for guiding the sliding movement of the piston (18);
A cylinder head (16) coupled to the cylinder block (15), closing the cylinder bore (19) and defining a combustion chamber (22) between the piston (18);
A fuel injection device (38) having an injection port (45) for injecting fuel facing the combustion chamber (22);
The through hole (57) that is inserted into the mounting hole (54) of the cylinder head (16) and receives the fuel injection device (38), and has a thermal conductivity lower than that of the cylinder head (16). An internal combustion engine comprising: a low thermal conductive material guide (56).
2. The internal combustion engine according to claim 1, wherein the low thermal conductive material guide (56) is a resin body.
3. The internal combustion engine according to claim 1, wherein the internal combustion engine is air-cooled.
The internal combustion engine according to any one of claims 1 to 3, further comprising a metal shielding wall (58) that partitions the low thermal conductive material guide (56) and the combustion chamber (22). Internal combustion engine.
5. The internal combustion engine according to claim 4, wherein the shielding wall (58) is fixed to a tip of the low thermal conductive material guide (56).
The internal combustion engine according to any one of claims 1 to 5, wherein the low thermal conductive material guide (56) is a seating surface defined by an outer surface of the cylinder head (16) around the mounting hole (54). (55) and a large diameter portion (59) sandwiched between a step surface (46) formed in the fuel injection device (38) and facing the seat surface (55). Internal combustion engine.
The internal combustion engine according to any one of claims 1 to 6, wherein the fuel injection device (38) includes a cylindrical nozzle (44) positioned in the attachment hole (54) that defines a cylindrical space; An internal combustion engine having an annular seal portion (61) protruding from the outer surface of the nozzle (44) and continuing in the circumferential direction.