阅读说明：本技术 气缸盖及内燃机 (Cylinder head and internal combustion engine ) 是由 大芦嘉郎 于 2018-06-01 设计创作，主要内容包括：本发明的气缸盖具备：第一部分,形成有供喷射器插入的插入孔,该喷射器对内燃机的燃烧室喷射燃料；第二部分,在插入孔内与喷射器及第一部分热接触,且热阻比第一部分的热阻大。(The cylinder head of the present invention includes: a first portion formed with an insertion hole into which an injector that injects fuel into a combustion chamber of an internal combustion engine is inserted; the second portion is in thermal contact with the injector and the first portion in the insertion hole, and has a thermal resistance greater than that of the first portion.)

1. A cylinder head includes:

a first portion formed with an insertion hole into which an injector that injects fuel into a combustion chamber of an internal combustion engine is inserted; and

a second portion in thermal contact with the injector and the first portion within the insertion hole, and having a thermal resistance greater than a thermal resistance of the first portion.

2. The cylinder head of claim 1,

the second portion is a portion that supports the ejector in the insertion hole.

3. The cylinder head of claim 2,

the insertion hole has a large diameter portion and a small diameter portion having an inner diameter smaller than that of the large diameter portion,

the second portion is provided at an end of the large diameter portion at a boundary portion of the large diameter portion and the small diameter portion.

4. The cylinder head of claim 1,

the second portion is integrally formed with the first portion.

5. An internal combustion engine, comprising:

the cylinder head of claim 1; and

an injector inserted into the insertion hole.

6. The internal combustion engine of claim 5,

a sealing member that suppresses leakage of gas from between the first portion and the injector,

the second portion is in thermal contact with the injector via the sealing member.

7. The internal combustion engine of claim 6,

the second portion has a thermal resistance greater than a thermal resistance of the seal member.

Technical Field

The present invention relates to a cylinder head into which an injector is inserted, and an internal combustion engine.

Background

Conventionally, in a cylinder head into which an injector is inserted in an internal combustion engine, a packing (packing) having good thermal conductivity is provided between the injector and the cylinder head (for example, see patent document 1). By so doing, the heat of the injector is made easy to transfer to the cylinder head, so that overheating of the injector can be suppressed.

Disclosure of Invention

Problems to be solved by the invention

However, in the configuration described in patent document 1, when the operation of immediately stopping the engine is performed while the engine is operating, the cylinder head may excessively receive heat from the injector, and the surface temperature of the injector may decrease. Therefore, moisture in the gas entering between the injector and the cylinder head may adhere to the surface of the injector and cause dew condensation. If dew condensation occurs on the ejector, the ejector may corrode.

The present invention aims to provide a cylinder head and an internal combustion engine capable of suppressing excessive heat extraction from an injector by the cylinder head and further suppressing corrosion of the injector.

Means for solving the problems

The cylinder head of the present invention includes:

a first portion formed with an insertion hole into which an injector that injects fuel into a combustion chamber of an internal combustion engine is inserted; and

a second portion in thermal contact with the injector and the first portion within the insertion hole, and having a thermal resistance greater than a thermal resistance of the first portion.

An internal combustion engine of the present invention includes:

the cylinder head described above; and

an injector inserted into the insertion hole.

Effects of the invention

According to the present invention, excessive heat extraction from the injector by the cylinder head can be suppressed, and injector corrosion can be suppressed.

Drawings

Fig. 1 is a diagram showing an internal combustion engine according to the present embodiment.

Fig. 2 is a view showing a packing according to a modification.

Detailed Description

The present embodiment will be described in detail below with reference to the drawings. Fig. 1 is a diagram showing an internal combustion engine 1 according to the present embodiment.

As shown in fig. 1, an internal combustion engine 1 is mounted on a vehicle, for example, a diesel engine, and includes a cylinder head 10 and an injector 20.

The cylinder head 10 has: a first portion 12 formed with an insertion hole 11 into which the ejector 20 is inserted; and a second portion 13 supporting the ejector 20 in the insertion hole 11. The insertion hole 11 is formed so as to open into the combustion chamber 2 of the internal combustion engine 1.

The second portion 13 is formed of a different material from the first portion 12, and is integrally formed with the first portion 12 by insert casting (insert process). That is, the second portion 13 is in thermal contact with the first portion 12 by being in direct contact with the first portion 12. The materials of the first portion 12 and the second portion 13 will be described later.

The injector 20 injects fuel into the combustion chamber 2, and has a cylindrical main body portion 21 and a tip end portion 22 having a smaller diameter than the main body portion 21.

The insertion hole 11 in the cylinder head 10 is constituted by a large diameter portion 11A and a small diameter portion 11B. The large diameter portion 11A is a portion into which the main body portion 21 of the ejector 20 is inserted, and the small diameter portion 11B is a portion into which the tip portion 22 of the ejector 20 is inserted. The inner diameter of the small diameter portion 11B is smaller than that of the large diameter portion 11A.

The second portion 13 is provided at a lower end portion of the large diameter portion 11A, which is a boundary portion between the large diameter portion 11A and the small diameter portion 11B, and is formed in a ring shape into which the tip end portion 22 of the injector 20 can be fitted.

The second portion 13 is in thermal contact with the ejector 20 and the first portion 12. Specifically, the lower end portion of the body portion 21 of the injector 20, that is, the portion of the body portion 21 located outside the distal end portion 22 is disposed on the upper surface of the second portion 13 with the packing 30 as an example of a sealing member interposed therebetween. Thereby, the second portion 13 is in thermal contact with the injector 20 via the packing 30.

The packing 30 is interposed between the injector 20 and the second portion 13, and is disposed so as to seal between the cylinder head 10 and the injector 20. This prevents gas and the like from leaking between the cylinder head 10 and the injector 20.

The packing 30 is made of copper, for example, and has a relatively low thermal resistance. Thus, when the injector 20 is overheated as the internal combustion engine 1 is operated, the heat of the injector 20 is easily transmitted to the second portion 13 through the packing 30.

The second portion 13 is in thermal contact with the first portion 12, so that heat from the injector 20 is transferred to the first portion 12 via the packing 30 and the second portion 13. That is, the heat of the injector 20 is diffused toward the first portion 12 side.

However, when the internal combustion engine 1 is operated, the cylinder head 10 may excessively extract heat from the injector 20. For example, the above phenomenon occurs when the internal combustion engine 1 is stopped after a relatively short period of time in which the internal combustion engine 1 is operated in order to charge the battery when the vehicle is left unused for a long period of time.

In this case, the injector 20 is cooled, that is, the surface temperature of the injector 20 is lowered, and therefore, for example, dew condensation may occur due to moisture in the gas entering the gap between the cylinder head 10 and the injector 20. If the vehicle is left unused for a long period of time in a state where such condensation occurs, the portion of the injector 20 where condensation occurs may corrode.

Therefore, in the present embodiment, the thermal resistance of the second portion 13 is higher than the thermal resistance of the first portion 12, which is a portion of the cylinder head 10 other than the second portion 13, and the thermal resistance of the packing 30.

Accordingly, since heat is less likely to be transferred from the injector 20 to the first portion 12, the occurrence of dew condensation due to excessive cooling of the injector 20 can be suppressed, and the occurrence of corrosion in the injector 20 can be suppressed.

The material constituting the first portion 12 is, for example, aluminum, and the material constituting the second portion 13 is, for example, stainless steel (SUS).

Since aluminum is lighter than aluminum, for example, when aluminum is used as the first portion 12 of the cylinder head 10 in a vehicle on which a load is loaded such as a truck, a larger amount of the load can be loaded on the vehicle.

In addition, in the case where the first portion 12 is made of aluminum, aluminum generally has a small thermal resistance and thus has good thermal conductivity. Therefore, the heat transfer performance from the injector 20 via the packing 30 and the like is improved. However, since the heat transfer performance is good, when the internal combustion engine 1 is stopped after the internal combustion engine 1 is operated for a relatively short time, the injector 20 is liable to be cooled excessively.

Therefore, by forming the second portion 13 from SUS, which is a material having a relatively high thermal resistance, the thermal resistance obtained by summing the first portion 12 and the second portion 13 can be made to be a thermal resistance similar to a structure in which a member having a relatively high thermal resistance is used as the first portion 12.

Here, the thermal resistance of the structure in which the first portion 12 is made of aluminum and the second portion 13 is made of SUS is compared with the thermal resistance of the structure in which the first portion 12 is made of cast iron having relatively high thermal resistance. Table 1 shows the thermal resistance of cast iron and aluminum, and table 2 shows the thermal resistance of SUS when the thickness is set to 0.3mm, 0.7 mm. Table 3 shows the thermal resistance of the first portion 12 (aluminum) and the second portion 13(SUS) in total, and the ratio of the thermal resistance to the thermal resistance of cast iron.

The unit of the thermal resistance in tables 1 to 3 is m²DEG c/W. In table 3, "ratio to cast iron" represents a ratio of thermal resistance of the first portion 12 (aluminum) and the second portion 13(SUS) in total to thermal resistance of cast iron. Each numerical value shown in table 3 is calculated based on the numerical values shown in tables 1 and 2.

[ Table 1]

	Cast iron	Aluminium
			Thermal resistance	1.19E-04	6.36E-05

[ Table 2]

Thickness of	0.3	0.7
			Thermal resistance	1.84E-05	4.29E-05

[ Table 3]

Thickness of	Thermal resistance	Ratio to cast iron
			0.3	8.20E-05	68.9％
0.7	1.07E-04	89.5％

As shown in table 2, since the thermal resistance increased as the thickness of SUS increased, it was confirmed that the thermal resistance obtained by summing the first portion 12 and the second portion 13 gradually approached the thermal resistance of the structure using cast iron as the first portion 12 as shown in table 3.

That is, in the present embodiment, even if the first portion 12 is made of aluminum having relatively low thermal resistance, the heat transfer performance can be made equivalent to the heat transfer performance of a structure having thermal resistance similar to cast iron.

As shown in table 2, when the thickness of the second portion 13 is changed, the thermal resistance of the second portion 13 changes, and therefore the thermal resistance between the cylinder head 10 and the injector 20 can be adjusted to a desired value.

In addition, the value of the thermal resistance between the cylinder head 10 and the injector 20 may be adjusted by adjusting the ratio of the thickness of the second portion 13 to the thickness of the packing 30.

In the above embodiment, the packing 30 has a rectangular cross-sectional shape, but may have a cross-sectional shape having the convex portions 31 on the upper surface and the lower surface, as shown in fig. 2, for example. The second portion 13 may have a shape matching the shape of the packing 30.

In the above embodiment, the second portion 13 is located at the boundary portion between the large diameter portion 11A and the small diameter portion 11B, but the present invention is not limited to this, and for example, the second portion 13 may be located on the wall forming the large diameter portion 11A or the small diameter portion 11B. In this case, the outer peripheral surface of the injector 20 may be sandwiched by the second portion 13 in thermal contact with the wall.

The above embodiments are merely examples of embodying the present invention, and the technical scope of the present invention should not be limited by these embodiments. That is, the present invention can be implemented in various forms without departing from the gist or main features thereof.

The present application is based on the japanese patent application (japanese patent application 2017-108999) filed on 1/6.2017, the contents of which are hereby incorporated by reference in their entirety.

Industrial applicability

The cylinder head and the internal combustion engine according to the present invention are useful as a cylinder head and an internal combustion engine that can suppress excessive heat extraction from the injector by the cylinder head and further suppress corrosion of the injector.

Description of the reference numerals

1 internal combustion engine

2 combustion chamber

10 cylinder head

11 inserting into the hole

11A large diameter part

11B minor diameter portion

12 first part

13 second part

20 ejector

21 main body part

22 front end portion

30 packing