JP2000337151A - Overhead valve type cylinder head for diesel engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of a crack between the valves of a cylinder head while reducing the weight of an engine and while preventing the occurrence of fall of a nozzle hole mouthpiece. SOLUTION: A nozzle hole mouthpiece 21 is installed in a combustion auxiliary chamber 11 of an overhead valve type cylinder head 1 provided with the combustion auxiliary chamber 11 and an intake and an exhaust valves 34, 35. A head main body 10 of this cylinder head 1 is formed by cast molding the aluminum material, and a heat resistant member 20 having a diameter larger than that of a cylinder bore 6 is installed in a part of the head main body 10 opposite to the combustion chamber, and the nozzle hole mouthpiece 21 is fixed through the heat resistant member 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an overhead valve type cylinder head for a diesel engine, and more particularly to a technique for preventing a nozzle hole of a sub-combustion chamber from falling off.

[0002]

2. Description of the Related Art Generally, an overhead valve type cylinder head of a diesel engine is provided with a combustion auxiliary chamber and an intake / exhaust valve, and is formed of a cast iron or the like as a mold. In the lower half of the combustion subchamber, a nozzle hole made of a heat-resistant material (cast iron, special steel, sintered alloy, etc., the same applies hereinafter) is mounted.

[0003]

However, the cylinder head made of cast iron is heavy, which is against the weight reduction of the engine. Therefore, it is conceivable to mold the cylinder head with an aluminum material.However, when a nozzle hole made of a heat-resistant material is pressed into an aluminum cylinder head, the difference in the coefficient of thermal expansion between the two causes high engine load. -There is a risk that the nozzle hole may fall off during high heat. Further, when the entire cylinder head is integrally formed of an aluminum material as a mold, there is a possibility that cracks may occur between the intake and exhaust valves of the cylinder head due to thermal stress or strong strain stress. The present invention has been made in view of such circumstances, and it is an object of the present invention to prevent the above-described injection hole nozzle from dropping off and prevent a crack in an inter-valve portion while reducing the weight of an engine. .

[0004]

In order to solve the above-mentioned problems, the present invention is configured as follows. That is, claim 1
The invention described in (1) describes the combustion sub-chamber 11 and the intake / exhaust valves 34 and 35
And a head body 1 of the cylinder head 1 in an overhead valve type cylinder head of a diesel engine having a nozzle hole 21 mounted on a lower half portion of the combustion auxiliary chamber 11.
0 is formed from an aluminum material, and a heat-resistant member 20 having a diameter larger than the diameter of the cylinder bore 6 is mounted on the surface of the head main body 10 facing the combustion chamber. It is characterized by being fixed.

According to a second aspect of the present invention, in the overhead valve type cylinder head for a diesel engine according to the first aspect, valve seats 24 and 25 of intake and exhaust valves 34 and 35 are integrally formed with the heat-resistant member 20. It is characterized by that.

According to a third aspect of the present invention, there is provided a diesel engine having a combustion auxiliary chamber 11 and intake / exhaust valves 34 and 35 and an injection hole base 21 attached to a lower half of the combustion auxiliary chamber 11. In the overhead valve type cylinder head, the head body (10) of the cylinder head (1) is formed of a mold made of an aluminum material, and the outer peripheral surface of the injection hole base 21 and the inner circumference of the base insertion hole 37 of the head body 10 are formed. The clip mounting grooves 26 and 36 are formed over the surface, and a circlip 27 is mounted in the clip mounting grooves 26 and 36 to prevent the nozzle hole 21 from coming off.

[0007]

According to the present invention, the following functions and effects can be obtained. (A) According to the first aspect of the present invention, since the head body 10 of the cylinder head 1 is formed of a mold using an aluminum material,
It is possible to reduce the weight of the engine, reduce the vibration by lowering the center of gravity, simplify the cooling system by increasing the heat dissipation, and reduce the cost by eliminating the painting of the cylinder head.

(B) According to the first aspect of the present invention, a heat-resistant member 20 having a diameter larger than the diameter of the cylinder bore 6 is mounted on a portion of the head body 10 facing the combustion chamber, and the injection is performed through the heat-resistant member 20. Since the hole base 21 is fixed, the difference in the coefficient of thermal expansion between the heat-resistant member 20 and the injection hole base 21 is reduced. This makes it possible to prevent the nozzle hole from falling off when the engine is under a high load and high heat. Moreover, since the heat-resistant member 20 is more resistant to thermal stress and strain stress than the head body 10 made of aluminum material, it is possible to prevent cracks in the valve section of the cylinder head.

(C) According to the second aspect of the present invention, in the overhead valve type cylinder head of the diesel engine according to the first aspect, the intake / exhaust valves (34.3) are provided on the heat resistant member (20).
Since the valve seats 24 and 25 of No. 5 were integrally formed, compared with the case where the valve seats were formed as separate parts,
The number of parts is reduced, and the cost can be reduced.

(D) According to the third aspect of the present invention, the head body 10 of the cylinder head 1 is formed of an aluminum material as a mold, and the outer peripheral surface of the injection hole base 21 and the base insertion hole 37 of the head body 10 are formed. The mounting grooves 26 and 36 of the circlip 27 are formed over the inner peripheral surface to form
1 prevents the heat-resistant member 20 from becoming unnecessary, and the structure becomes simpler and the production becomes easier because the heat-resistant member 20 is not required.

[0011]

Embodiments of the present invention will be described below in more detail with reference to the drawings. FIG. 1 shows the first embodiment of the present invention.
1 is a vertical sectional view of the cylinder head according to the embodiment, and FIG. 2 is a bottom view of the cylinder head in FIG. FIG. 3 is an enlarged view of a main part of the cylinder head in FIG.
3A shows the first embodiment, and FIG. 3B shows the second embodiment. FIG. 4 is a vertical cross-sectional view taken along line BB in FIG. 1, and FIG.
(B) shows a second embodiment, respectively.

A head body 10 constituting the overhead valve type cylinder head 1 is formed of a mold of aluminum material, and is fixed to a cylinder block 5 of a diesel engine E with a plurality of fastening bolts as shown in FIG. As shown in FIGS. 1 and 2, the head main body 10 includes a combustion sub-chamber 11 and intake and exhaust valves 34 and 35, and an injection hole made of molybdenum cast iron, which is a heat-resistant material, is provided in a lower half of the combustion sub-chamber 11. The base 21 is fixed. The reason why the head body 10 is formed of a mold of aluminum material is to reduce the weight of the engine, reduce the vibration by lowering the center of gravity, simplify the cooling system by increasing heat dissipation, and paint the cylinder head. Is intended to reduce costs.

An oil cooling chamber 15 is formed around the combustion sub-chamber 11, and the cooling oil supplied by the pressure pump 13 is supplied to the cooling oil passage 14, the oil cooling chamber 15, the connecting pipe 16, and the oil cooler. 4 to the oil tank 12 in order. Here, reference numeral 2 in FIG. 1 denotes a head cover, 3 denotes a fuel injector, 6 denotes a cylinder bore, 7 denotes a piston, and 8 denotes a fuel injection pump. The intake / exhaust valves 34 and 35 are driven via a valve operating camshaft 31, a tappet 32, and a rocker arm 33 that constitute a valve operating mechanism. Hereinafter, a configuration which is a feature of the present invention will be described.

In the first embodiment of the present invention, FIGS.
As shown in FIG. 3A, a heat-resistant member 20 made of gray cast iron is fixed by press-fitting into a press-fitting concave portion 17 formed in a portion of the head main body 10 facing the combustion chamber, and the heat-resistant member 20 is interposed therebetween. The injection hole nozzle 21 is fixed. This reduces the difference in the coefficient of thermal expansion between the heat-resistant member 20 and the nozzle hole cap 21 to prevent the nozzle hole cap 21 from dropping off when the engine is under a high load and high heat, and to provide a heat-resistant member made of gray cast iron. 20 is more resistant to thermal stress and strain stress than the head body 10 made of an aluminum material, and is intended to prevent a crack in the inter-valve portion of the cylinder head.

As shown in FIGS. 1 and 2, the heat-resistant member 20 is formed to have a larger diameter than the diameter of the cylinder bore 6. When the cylinder head 1 is fastened and fixed to the cylinder block 5, the gasket 29 is fixed. The top block 30 of the cylinder block 5 is press-fixed and fixed. this is,
The purpose is to surely prevent the heat-resistant member 20 from falling off.

As shown in FIG. 1 and FIG. 3A, the injection hole base 21 mounted on the lower half of the sub-combustion chamber 11 has a large diameter portion 21b and a small diameter portion 21a. The heat-resistant member 20 is press-fitted into the press-fitting recess 17 in a state where the small-diameter portion 21a is press-fitted and fixed in the base insertion hole 37a formed in the heat-resistant member 20 by a tight fit. The portion 21b is configured to be fitted into the base insertion hole 37b of the head body 10. This is intended to more reliably prevent the nozzle hole cap 21 from falling off.

As shown in FIG. 1 and FIG. 2, the injection hole mouthpiece 21 has an injection hole 22 for forming a vortex, and is configured to form a vortex in the sub combustion chamber 11 at the end of the compression stroke. . In addition, as shown in FIG.
After making the diameter of the insertion portion 1 constant and inserting the insertion portion into the base insertion hole 37a formed in the heat-resistant member 20 by press-fitting,
The heat-resistant member 20 may be press-fitted into the press-fit recess 17.

In the first embodiment, the valve seats 24 and 25 of the intake and exhaust valves 34 and 35 are the same as those shown in FIGS.
As shown in FIG. 2A, the heat-resistant member 20 is formed separately from the heat-resistant member 20, and is press-fitted and fixed in an insertion hole of the heat-resistant member 20. However, as shown in FIG. 4B, the valve seats 24 and 25 may be formed integrally with the heat-resistant member 20 made of gray cast iron. In this case, the number of parts is reduced and the cost can be reduced as compared with the case where the valve seat is formed of another part.

FIG. 5 is a longitudinal sectional view of a main part of a cylinder head according to a second embodiment of the present invention. In this embodiment,
The head body 10 of the cylinder head 1 is formed of a mold of an aluminum material, and the clip mounting grooves 26 and 36 are formed over the outer peripheral surface of the insertion portion of the nozzle hole base 21 and the inner peripheral surface of the base insertion hole 37 of the head body 10. Then, the circlip 27 is mounted in the clip mounting grooves 26 and 36 to prevent the nozzle hole 21 made of molybdenum cast iron from coming off. This is intended to simplify the structure by making the heat-resistant member 20 unnecessary, thereby facilitating the manufacture.

As shown in FIG. 5, the base insertion hole 37 is formed with a large-diameter hole portion 37a and a circlip 27 in order from the bottom.
The clip mounting groove 36 is formed in the small-diameter hole portion 37b. The circlip 27 is formed of a spring material so that the diameter of the circlip 27 increases. The circlip 27 is inserted into a clip mounting groove 26 formed in a small-diameter portion (insertion portion) 21 b of the injection hole base 21. The circlip 27 is pushed into the guide hole portion 2 by pushing the injection hole base 21 into the base insertion hole 37 in a state of loose fitting.
7c and reduced in diameter to reduce the diameter of the small hole portion 3.
7b, and fits into the clip mounting groove 36 formed in the small diameter hole portion 37b. In this embodiment, the large-diameter portion 21 a of the nozzle hole base 21 is press-fitted into the large-diameter hole portion 37 a of the base insertion hole 37 by interference fit.

The present invention is not limited to the above-described embodiment, and the specific forms of the nozzle hole base 21 and the nozzle holes 22 can be implemented with appropriate modifications.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a cylinder head according to a first embodiment of the present invention.

FIG. 2 is a bottom view of the cylinder head taken along line AA in FIG.

FIG. 3 is an enlarged view of a main part of the cylinder head in FIG. 1,
FIG. 3A shows the first embodiment, and FIG. 3B shows the second embodiment.

FIG. 4 is a vertical sectional view taken along line BB in FIG. 1;
FIG. 4A shows the first embodiment, and FIG. 4B shows the second embodiment.

FIG. 5 is a vertical sectional view of a main part of a cylinder head according to another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Cylinder head, 6 ... Cylinder bore, 10 ... Head main body, 11 ... Combustion sub-chamber, 20 ... Heat resistant member, 21 ... Injection nozzle, 24/25 ... Valve seat, 26/36 ... Clip mounting groove, 27 ... Circle , 34/35 ... intake / exhaust valves, 37 ... hole for inserting a base in the head body, E ... diesel engine.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02F 1/24 F02F 1/24 B

Claims (3)

[Claims] 1. An auxiliary combustion chamber (11) and an intake / exhaust valve (34.
35), wherein an overhead valve type cylinder head of a diesel engine comprising a nozzle hole (21) mounted on a lower half portion of the combustion sub-chamber (11), wherein the head body (10) of the cylinder head (1) is provided. ) With aluminum material as a mold, and the head body (1)
A heat-resistant member (20) having a diameter larger than the diameter of the cylinder bore (6) is attached to the combustion chamber facing surface portion of (0), and the injection hole base (21) is fixed through the heat-resistant member (20). An overhead valve type cylinder head for a diesel engine. 2. The overhead valve type cylinder head of a diesel engine according to claim 1, wherein valve seats (24, 25) of intake and exhaust valves (34, 35) are formed integrally with the heat-resistant member (20). An overhead valve type cylinder head for a diesel engine. 3. An auxiliary combustion chamber (11) and an intake / exhaust valve (34.
35), wherein an overhead valve type cylinder head of a diesel engine comprising a nozzle hole (21) mounted on a lower half portion of the combustion sub-chamber (11), wherein the head body (10) of the cylinder head (1) is provided. ) Is formed from an aluminum material, and the nozzle hole cap (21) is formed.
The clip mounting groove (26.3) extends over the outer peripheral surface of the base and the inner peripheral surface of the base insertion hole (37) of the head body (10).
6), a circlip (27) is mounted in the clip mounting groove (26, 36), and the injection hole nozzle (21) is prevented from falling off. .