JP2002115601A - Exhaust port structure for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reconcile the durability of an exhaust port of an internal combustion engine and the effective use of exhaust gas energy. SOLUTION: The exhaust port 17 provided in a cylinder head 12 is divided into an upstream exhaust port 29 and a downstream exhaust port 30, and the upstream exhaust port 29 extending from a combustion chamber 14 beyond a valve stem 24a of an exhaust valve 24 is made directly in a cylinder head body 31 and the downstream exhaust port 30 ranging over the upstream exhaust port 29 and opening to a side face 31a of the cylinder head body 31 is constructed by a separate member from the cylinder head body 31 and supported by the cylinder head body 31 via a heat insulating material 35 and heat insulating spaces 37, 38. A water jacket 45 for the cylinder head body 31 is provided around the upstream exhaust port 29 except around the downstream exhaust port 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine in which an exhaust port provided inside a cylinder head comprises an upstream exhaust port and a downstream exhaust port.

[0002]

2. Description of the Related Art Japanese Utility Model Publication No. 59-174308 discloses that
An evaporator that heats the liquid-phase working medium with exhaust gas of the internal combustion engine to generate steam, an expander driven by the steam generated by the evaporator, and a liquid-phase working medium that cools the steam that has passed through the expander And a supply pump that pressurizes the liquid-phase working medium from the condenser and supplies the pressurized liquid-phase working medium to the evaporator. Describes a method of preheating a liquid-phase working medium and cooling an internal combustion engine by passing heat through a cylinder head and a cylinder block.

[0003] Also, Japanese Patent Application Laid-Open No. 5-256191 discloses that
Covering the inner surface of the exhaust port of the internal combustion engine with an exhaust passage liner mainly composed of silicon carbide, alumina and aluminum,
It describes that a mullite layer is formed on the surface in contact with the exhaust gas to improve the toughness, heat resistance and heat insulation of the exhaust passage liner.

[0004]

SUMMARY OF THE INVENTION By the way, the above-mentioned actual opening 5
In a system utilizing the energy of exhaust gas of an internal combustion engine, such as the Rankine cycle device described in JP-A-9-174308, it is desirable to supply the exhaust gas to the evaporator while keeping the temperature of the exhaust gas as high as possible. In order to satisfy this requirement, if the exhaust port is covered with heat insulating material and the cooling effect of the cooling water circulating in the water jacket is weakened, the exhaust port is exposed to high temperature, particularly in a portion close to the combustion chamber, and is easily deformed. This may cause a decrease in durability.

The present invention has been made in view of the above circumstances, and has as its object to achieve both durability of an exhaust port of an internal combustion engine and effective use of energy of exhaust gas.

[0006]

According to the first aspect of the present invention, an exhaust port provided inside a cylinder head is connected to an upstream exhaust port and a downstream exhaust port. An upstream exhaust port extending from the combustion chamber to a position beyond the valve stem of the exhaust valve is directly formed in the cylinder head main body, and a downstream exhaust port connected to the upstream exhaust port and opening on the side surface of the cylinder head main body is provided. An exhaust port structure for an internal combustion engine, comprising a separate member from the cylinder head body, supported by the cylinder head body via a heat insulating layer, and cooling means for the cylinder head provided around the upstream exhaust port. Is proposed.

According to the above construction, the upstream exhaust port, that is, from the combustion chamber to a position beyond the valve stem of the exhaust valve is directly formed in the cylinder head body, and the cooling means for the cylinder head is provided with the upstream exhaust port. , The rigidity and cooling effect of the portion of the exhaust port exposed to the hottest exhaust gas can be enhanced, and the durability can be improved. Also, a downstream exhaust port, that is, a portion that opens to the side surface of the cylinder head main body connected to the upstream exhaust port is formed of a separate member from the cylinder head main body, is supported by the cylinder head main body via a heat insulating layer, and Since no cooling means is provided around the downstream exhaust port, it is possible to minimize the temperature of the exhaust gas that has decreased slightly when passing through the upstream exhaust port and further decrease while passing through the downstream exhaust port. Can be minimized. In this way, the upstream exhaust port performs active cooling to ensure durability, and the downstream exhaust port performs heat insulation to suppress a decrease in exhaust gas temperature, thereby improving exhaust port durability and exhaust gas. Energy can be effectively used at the same time.

According to the invention described in claim 2,
In addition to the structure of claim 1, an exhaust port structure for an internal combustion engine is proposed, wherein the cooling means for the cylinder head is provided at least around the exhaust valve.

According to the above configuration, since the cooling means for the cylinder head is provided around the exhaust valve, the durability of the exhaust valve exposed to high-temperature exhaust gas can be improved.

The heat insulating material 35 of the embodiment, the first heat insulating space 3
7 and the second heat insulating space 38 correspond to the heat insulating layer of the present invention,
The water jacket 44 and the cooling oil passage 47 of the embodiment correspond to the cooling means of the present invention.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described based on embodiments of the present invention shown in the accompanying drawings.

1 to 3 show an embodiment of the present invention. FIG. 1 is a view showing the overall configuration of a Rankine cycle device.
2 is an enlarged view of a main part of FIG. 1 (a sectional view taken along line 2-2 of FIG. 3), and FIG. 3 is a sectional view taken along line 3-3 of FIG.

As shown in FIG. 1, a Rankine cycle device 2 that recovers thermal energy of exhaust gas of an internal combustion engine 1 and outputs mechanical energy has a high temperature by heating water using the exhaust gas of the internal combustion engine 1 as a heat source. An evaporator 3 for generating high-pressure steam, an expander 4 for outputting an axial torque by expansion of the high-temperature and high-pressure steam, a condenser 5 for cooling and liquefying the cooled down-pressure steam discharged from the expander 4, Vessel 5
And a supply pump 6 for pressurizing the water discharged from the evaporator 3 and supplying the pressurized water to the evaporator 3 again. In this embodiment, an exhaust gas purifying device 7 is integrally formed on the downstream side of the evaporator 3 as viewed in the flow direction of the exhaust gas, and an exhaust pipe 8 is connected on the downstream side.

As apparent from FIGS. 2 and 3, the internal combustion engine 1 includes a cylinder block 11 and a cylinder head 12 coupled to an upper surface thereof.
Piston 13 slidably fitted in cylinder bore 11a
A combustion chamber 14 facing the top surface of the cylinder head 12 is formed on the lower surface of the cylinder head 12. The downstream side of the intake port 15 formed in the cylinder head 12 is bifurcated and connected to a pair of intake valve seats 16, 16 facing the combustion chamber 14, and upstream of the exhaust port 17 formed in the cylinder head 12. The side is bifurcated and connected to a pair of exhaust valve seats 18 facing the combustion chamber 14. Valve stem 19
a, 19a are guided by the valve guides 20, 20, and the pair of intake valves 19, 19 are slidably connected to the cylinder head 1.
2 are seated on the intake valve seats 16 by being urged by valve springs 23, 23 contracted between the spring seats 21, 21 supported by the stem 2 and the spring seats 22, 22 supported by the stem end. Valve stem 24a,
A pair of exhaust valves 24, 24 slidingly guided by the valve guides 25, 25 are compressed between spring seats 26, 26 supported by the cylinder head 12 and spring seats 27, 27 supported by the stem end. It is urged by the provided valve springs 28 and 28 and sits on the exhaust valve seats 18. And the intake valve 19,1
9 and the exhaust valves 24, 24 are driven by a valve train (not shown) to open and close the intake port 15 and the exhaust port 17, respectively.

The exhaust port 17 comprises a pair of upstream exhaust ports 29, 29 close to the combustion chamber 14 and a downstream exhaust port 30 far from the combustion chamber 14, and the upstream exhaust ports 29, 29 are made of an aluminum alloy. The downstream exhaust port 30 is formed of a pipe material having an elliptical cross section. The upstream ends of the upstream exhaust ports 29, 29 are connected to the combustion chamber 14, and the downstream ends extend to positions beyond the valve stems 24a, 24a of the exhaust valves 24, 24. The cylinder head main body 31 is formed with a concave portion 31b that is opened on the side surface 31a, and the exhaust port heat insulating unit 32 including the downstream exhaust port 30 is mounted in the concave portion 31b. The exhaust port heat insulating unit 32 includes a downstream side exhaust port 30, heat insulating material holders 33 and 34 fixed to both ends thereof, and an elliptic cylindrical heat insulating material fixed so as to be sandwiched between the heat insulating material holders 33 and 34. 35 are integrated.

With the exhaust port heat insulating unit 32 mounted in the concave portion 31b of the cylinder head body 31, a heat insulating seal member 36 is sandwiched between the upstream heat insulating material holder 33 and the bottom surface of the concave portion 31b. Side exhaust port 2
Exhaust gas is prevented from leaking from the connection between the exhaust ports 9, 29 and the downstream exhaust port 30. Also, the downstream exhaust port 30
The first heat insulating space 3 is provided between the outer peripheral surface of the
7 is formed, and a second heat insulating space 38 is formed between the outer peripheral surface of the heat insulating material 35 and the inner peripheral surface of the concave portion 31b. Insulation material 35
And both heat insulation spaces 37 and 38 constitute the heat insulation layer of the present invention.

A plurality of stud bolts 39 are implanted on the side surface 31a of the cylinder head body 31. A mounting flange 41 is formed at an upstream end of a casing 40 accommodating the evaporator 3 and the exhaust gas purifying device 7, and a nut 42 is screwed into a stud bolt 39 that passes through a bolt hole 41a of the mounting flange 41. By doing so, the casing 40 is fixed to the cylinder head body 31. At this time, the heat-insulating sealing member 43 supported by the mounting flange 41 of the casing 40 abuts on the heat-insulating material holder 34 on the downstream side of the exhaust port heat-insulating unit 32, and the exhaust from the connecting portion between the cylinder head body 31 and the mounting flange 41 Gas leakage is prevented.

A water jacket 4 through which cooling water circulates is provided in the cylinder block 11 and the cylinder head body 31.
4, 45 are respectively formed. Cylinder head body 3
The first water jacket 45 is connected to the upstream exhaust port 29,
Although it is arranged so as to surround the periphery of 29, it is not arranged around the downstream side exhaust port 30. In particular, the water jacket 45 of the cylinder head body 31 is intensively arranged near the exhaust valves 24 and 24 and the plug hole 46 where the temperature becomes high.
29 is actively cooled by the water jacket 45, while the downstream exhaust port 30 is
5 hardly cools. A cooling oil passage 47 through which cooling oil flows is formed around the valve guides 25 of the exhaust valves 24. The water jacket 45 and the cooling oil passage 47 of the cylinder head main body 31 constitute the cooling means of the present invention.

Next, the operation of the embodiment of the present invention having the above configuration will be described.

Exhaust gas discharged from the combustion chamber 14 by opening the exhaust valves 24, 24 is supplied to the upstream exhaust ports 29, 29 and the downstream exhaust port 30 of the exhaust port 17.
Is supplied to the evaporator 3 through the exhaust gas purifier 7 and discharged therefrom to the exhaust pipe 8. The upstream exhaust ports 29, 29 into which the exhaust gas discharged from the combustion chamber 14 flows are exposed to high temperatures, but the upstream exhaust ports 29, 29 directly formed in the cylinder head body 31 are resistant to thermal deformation. Moreover, since the surroundings are surrounded by the water jacket 45 and the cooling oil passage 47 and are sufficiently cooled, damage and deformation of the upstream exhaust ports 29 and 29 and the exhaust valves 24 and 24 due to heat of the exhaust gas are prevented. Durability is ensured.

The temperature of the exhaust gas passing through the upstream exhaust ports 29 and 29 and flowing into the downstream exhaust port 30 is slightly lowered, and the downstream exhaust port 30 is far from the combustion chamber 14 as a heat source. Therefore, the upstream exhaust port 29,
The durability against heat is originally higher than that of No. 29.
Therefore, the water jacket 45 is not formed around the downstream side exhaust port 30 and the exhaust port heat insulating unit 32
Even if the periphery is surrounded by the first and second heat insulating spaces 37 and 38 and the heat insulating material 35, the durability of the downstream side exhaust port 30 will not be affected. The exhaust gas passing through the insulated downstream exhaust port 30 is supplied to the evaporator 3 and the exhaust gas purification device 8 in a state where the temperature drop is minimized. The exhaust gas purification efficiency of the gas purification device 8 can be maximized. Moreover, since there is no need to form the water jacket 45 around the downstream side exhaust port 30, the amount of cooling water can be reduced to 60% of the conventional amount.

Although the embodiments of the present invention have been described in detail, the present invention can be variously modified without departing from the gist thereof.

For example, in the embodiment, the internal combustion engine 1 provided with the Rankine cycle device 2 is exemplified, but the present invention can be applied to any internal combustion engine 1 utilizing waste heat of exhaust gas.

[0024]

As described above, according to the first aspect of the present invention, the upstream exhaust port, that is, from the combustion chamber to a position beyond the valve stem of the exhaust valve, is directly bored in the cylinder head body. And, since the cooling means of the cylinder head is provided around the upstream side exhaust port,
The rigidity and cooling effect of the portion of the exhaust port exposed to the hottest exhaust gas can be enhanced to improve durability. Also, the downstream exhaust port, that is, the portion that opens to the side surface of the cylinder head body following the upstream exhaust port,
It is composed of a separate member from the cylinder head main body, is supported by the cylinder head main body via a heat insulating layer, and passes through the upstream exhaust port because no cooling means is provided around the downstream exhaust port. In this case, it is possible to minimize a further decrease in temperature of the exhaust gas whose temperature has decreased slightly while passing through the downstream exhaust port. in this way,
Active cooling at the upstream exhaust port ensures durability, and insulation at the downstream exhaust port suppresses exhaust gas temperature drop, thereby improving exhaust port durability and effective exhaust gas energy. It is possible to achieve both usage and usage.

According to the second aspect of the present invention,
Since the cooling means for the cylinder head is provided around the exhaust valve, the durability of the exhaust valve exposed to high-temperature exhaust gas can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall configuration of a Rankine cycle device.

2 is an enlarged view of a main part of FIG. 1 (a sectional view taken along line 2-2 in FIG. 3);

FIG. 3 is a sectional view taken along line 3-3 in FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 12 Cylinder head 14 Combustion chamber 17 Exhaust port 24 Exhaust valve 24a Valve stem 29 Upstream exhaust port 30 Downstream exhaust port 31 Cylinder head main body 31a Side surface 35 Heat insulating material (heat insulating layer) 37 First heat insulating space (heat insulating layer) 38 Second Insulated space (insulated layer) 45 Water jacket (cooling means) 47 Cooling oil passage (cooling means)

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Masakazu Miyao 1-4-1 Chuo, Wako-shi, Saitama Pref. Honda Technology Laboratory Co., Ltd. (72) Terumiko Fujisawa 1-4-1 Chuo, Wako-shi, Saitama No. F-term in Honda R & D Co., Ltd. (reference) 3G024 AA11 AA15 CA05 DA06 FA11

Claims (2)

[Claims] An exhaust port (17) provided inside a cylinder head (12) is composed of an upstream exhaust port (29) and a downstream exhaust port (30), and an exhaust valve (30) is provided from a combustion chamber (14). An upstream exhaust port (29) extending to a position beyond the valve stem (24a) of (24) is directly bored in the cylinder head body (31), and is connected to the upstream exhaust port (29). The downstream exhaust port (30) opening to the side surface (31a) is formed of a separate member from the cylinder head main body (31), and is supported by the cylinder head main body (31) via the heat insulating layers (35, 37, 38). An exhaust port structure for an internal combustion engine, wherein the cooling means (45, 47) of the cylinder head (12) is provided around the upstream exhaust port (29). 2. A cooling means (4) for cooling a cylinder head (12).
5. The exhaust port structure for an internal combustion engine according to claim 1, wherein the at least one of the exhaust ports is provided at least around the exhaust valve.