JPH1018907A - Cylinder head for direct injection type diesel engine, and casting die for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate molding a cooling water passage, in the cylinder head of a direct injection type diesel engine. SOLUTION: A cooling water passage 16 can be easily ensured around a nozzle hole 15A, in the case where the fitting boss 15 of a fuel injection nozzle having a cylinder head integrally formed type is formed by making a cooling water jacket forming core insertable; so that the insertion space of an exhaust port forming core can be ensured, and the exhaust port forming core can form a curved insertion locus, while detouring a fuel injection nozzle fitting position, by utilizing part of the existing space of an air intaking port forming core, or by the thick thickness part of an outer wall; by partially using in common the outer wall of the air intake port 12 (a common outer wall 17) of a cylinder adjoining the outer wall of an exhaust port 14A, and also forming part of the outer wall into thick thickness because the exhaust port 14A in the termination part of a cylinder head 11 has no adjoining air intake ports 12 and 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder head of a four-valve direct injection diesel engine and a casting structure thereof, and more particularly to a technique for forming a water passage in the cylinder head.

[0002]

2. Description of the Related Art Conventionally, a cylinder head has two intake valves and two exhaust valves, respectively, and the cylinder head has intake and exhaust valves which are opened and closed by the four valves (two intake valves and two exhaust valves). There is known a four-valve direct-injection diesel engine having four ports each having a fuel injection nozzle at a position corresponding to a substantially central portion of the four ports of the cylinder head.

In such a four-valve direct-injection diesel engine, conventionally, as an advantageous configuration for forming a cooling water passage around a nozzle hole of a fuel injection nozzle of a cylinder head, as shown in FIGS. The structure is adopted. That is, the cylinder head 1 is made of cast iron, and the mounting boss 6 of the fuel injection nozzle provided at a position corresponding to substantially the center of the intake ports 2 and 3 and the exhaust ports 4 and 5 of the cylinder head 1 is connected to the cylinder head 1. Is formed by press-fitting a separate pipe into the cylinder head 1.

Further, the arrangement of the four valves is a so-called diamond type, and the four valves are arranged at positions where the valve center is twisted with respect to the center axis of the cylinder bore. That is, the intake valve and the exhaust valve are arranged in a direction inclined at a predetermined angle with respect to the direction orthogonal to the axial direction of the crankshaft. Such a four-valve direct injection diesel engine has a configuration in which the mounting boss 6 of the fuel injection nozzle is formed by press-fitting a pipe into the cylinder head 1, so that the cooling water passage around the nozzle hole of the fuel injection nozzle is formed. Advantages of easy formation and cast iron cylinder head 1
Therefore, the material strength is high, and the pipe press-in allowance can be increased, so that the surface pressure of the press-fitted portion can be increased and the sealing performance of cooling water and gas is excellent, and the arrangement of the four valves 2 to 5 is a diamond type. Therefore, it is easy to form a cooling water passage between the mounting boss 6 of the fuel injection nozzle and the exhaust ports 4 and 5, and since the cylinder head 1 is made of cast iron, the wall thickness can be reduced. This has the advantage that the cooling water passage can be sufficiently secured.

[0005]

However, when manufacturing a direct injection type diesel engine having a DOHC type aluminum cast cylinder head, a conventional four-valve direct injection type diesel engine as described above is used. However, there are the following problems. That is, in the case where the mounting boss of the fuel injection nozzle is formed by press-fitting the pipe into the cylinder head, the press-fitting portion of the pipe cannot be increased because of the material strength of aluminum. Since the pressure cannot be increased, it is difficult to ensure the sealing performance of cooling water and gas.

In addition, the separate pipe press-fitting method is disadvantageous in terms of materials and processing costs. Furthermore, when the arrangement of the four valves is a diamond type, it is difficult to adopt a DOHC type valve train arrangement, and the rocker arm type SOHC
However, in such a format, it is difficult to secure an output in a high-speed range of the engine.

In view of the above situation, DOHC
In a direct-injection diesel engine having an aluminum cast cylinder head of the type, two intake valves and two exhaust valves for each cylinder are arranged in parallel in a direction substantially orthogonal to the center axis direction of the crankshaft. And the mounting boss of the fuel injection nozzle must be formed integrally with the cylinder head.

However, in such a configuration, it is difficult to form a cooling water passage around the nozzle hole of the fuel injection nozzle, and a cooling water passage is formed between the mounting boss of the fuel injection nozzle 3 and the exhaust port. The problem that it is difficult arises. Therefore, the present invention has been made to solve the above-mentioned conventional problems. Two intake valves and two exhaust valves of each cylinder are substantially orthogonal to the center axis direction of the crankshaft. It is an object of the present invention to facilitate the formation of a cooling water passage in a cylinder head of a direct injection diesel engine which is arranged so as to be parallel in the direction and in which a mounting boss of a fuel injection nozzle is integrally formed with a cylinder head.

[0009]

For this reason, the invention according to claim 1 is characterized in that a cylinder head made of casting has two cylinders for each cylinder.
The cylinder head includes four intake and exhaust ports that are opened and closed by the four valves for each cylinder, and the cylinder head has two intake valves and two exhaust valves for each cylinder. In a direct-injection diesel engine in which two exhaust valves are arranged in parallel in a direction substantially orthogonal to the center axis direction of the crankshaft, the rear side is determined based on the intake port opening position in the cylinder head side wall of the adjacent cylinder. The outer wall of each intake port extending to the exhaust port and the outer wall of each exhaust port adjacent to the intake port are connected at their closest point to share the port outer wall, and one end wall of the cylinder head in the cylinder row direction is provided. The outer wall of the exhaust port located on the side is formed thicker in comparison with the outer wall of the other part, while the outer wall of the exhaust port is located substantially at the center axis of the cylinder bore of each cylinder of the cylinder head. A fuel injection nozzle is provided upright, and a boss for mounting the fuel injection nozzle is formed integrally with the cylinder head. A cooling water passage is provided between each throat portion of the two exhaust ports and the boss for mounting the fuel injection nozzle. Was formed.

In the method according to the first aspect of the present invention, in the method of inserting the port forming core at the time of casting the cylinder head into the cooling water jacket forming core at right angles to the cylinder longitudinal direction, It is difficult to form a cooling water passage between the throat portion of the port and the mounting boss of the fuel injection nozzle. Therefore, the outer wall of the exhaust port and the outer wall of the intake port of the adjacent cylinder are partially shared, and the exhaust port at the end of the cylinder head does not have an adjacent intake port. By forming the exhaust port forming core, a space for inserting the exhaust port forming core can be secured, and the exhaust port forming core can be partially used in the existing space of the intake port forming core or at a thick portion of the outer wall. The fuel injection nozzle can be inserted into the cooling water jacket forming core so as to form a curved insertion trajectory while bypassing the fuel injection nozzle mounting position.

According to a second aspect of the present invention, the two intake ports are opened as a helical port and a tangential port on one side wall surface of a cylinder head and communicate with an intake manifold. As a single exhaust port where the flow from the throat portion of each port merges on the way, it opens to the other side wall surface of the cylinder head and communicates with the exhaust manifold.

In the invention according to claim 3, the cylinder head is made of aluminum casting. In the invention according to claim 4, the diesel engine is a DOHC type engine. The invention according to claim 5 has cooling water jackets at upper and lower portions of the exhaust port and at a lower portion of the intake port, respectively, and cools the upper and lower portions by the cooling water passage around a mounting boss of the fuel injection nozzle. It communicated with the water jacket.

According to a sixth aspect of the present invention, there is provided a casting die for casting a cylinder head of a direct-injection diesel engine according to the fifth aspect of the present invention, wherein a core for forming an exhaust port in a throat portion of the exhaust port and a lower cylinder head die. The dimension T1 of the upper surface height of the cooling water passage between the throat portions of the exhaust port or the upper height of the cooling water jacket below the exhaust port, the upper wall thickness T2 of the exhaust port, the cylinder T3, The height T4 and the allowance Δ of the port positioning tenon of the lower head die were set to have the following relationship.

T3> T1 + T4-T2-Δ In the invention according to the fifth aspect, it is possible to set the intake port forming core from above the cooling water jacket forming core. In this case, if it is intended to provide cooling water passages above and below the exhaust port, it is necessary to insert the exhaust port forming core horizontally in the exhaust port forming core arrangement space of the water jacket forming core.

In the invention according to claim 6, the overall height of the exhaust port is reduced, the setability of the exhaust port forming core is improved, and the width of the upper and lower cooling water passages is maximized. I have. Thus, the exhaust port forming core is lifted up using the space for the cooling water jacket forming core, which is the upper wall of the exhaust port, and the space for disposing the exhaust port forming core of the water jacket forming core. Inserted into the insertion part.

According to a seventh aspect of the present invention, a cylinder head made of casting is provided with two intake valves and two exhaust valves for each cylinder, and the cylinder head is opened and closed by the four valves for each cylinder. It has four ports for intake and exhaust respectively, and two intake valves and two exhaust valves for each cylinder are arranged in parallel in a direction substantially orthogonal to the center axis direction of the crankshaft. In a direct-injection diesel engine, the insertion trajectory of the exhaust port forming core used for casting in the cooling water jacket forming core used during casting is curved while bypassing the nozzle hole of the fuel injection nozzle, thereby cooling around the nozzle hole. A water passage was formed.

[0017]

According to the first and seventh aspects of the invention, for example, in a DOHC four-valve direct injection diesel engine having excellent output performance as in the third and fourth aspects, a lightweight aluminum cast cylinder is provided. A cooling water passage around the fuel injection nozzle mounting part when the head is used, the production cost is advantageous, and problems such as gas and water leakage do not easily occur. Can be easily secured, and the cooling performance and the durability can be improved.

According to the second aspect of the present invention, a strong swirling flow (swirl flow) in the lateral direction of the cylinder is formed by the intake air, so that the intake port shape and the exhaust port shape can improve the combustion performance. According to the invention according to claim 5, the setability of the intake port forming core can be improved,
Productivity can be improved.

According to the invention of claim 6, it is possible to improve the setability of the exhaust port forming core and to secure the maximum width of the upper and lower cooling water passages.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the attached drawings. 1 and 2, a cylinder head 11 made of aluminum casting of a direct-injection diesel engine is provided with two direct-acting intake valves and two exhaust valves (not shown), respectively.
There are formed four ports (intake ports 12, 13 and exhaust ports 14A, 14B) that are opened and closed by the four valves.

The two intake valves and the two exhaust valves for each cylinder are arranged in parallel in a direction substantially orthogonal to the central axis of the crankshaft. The two intake ports 12, 13 are opened as helical ports and tangential ports, respectively, on one side of the cylinder head 11, and communicate with an intake manifold (not shown).

Further, two exhaust ports 14A, 14B
Is a single exhaust port 14 in which the flows from the throat portions of the ports 14A and 14B join in the middle, and is opened to the other side surface of the cylinder head 11 and communicates with an exhaust manifold (not shown). On the other hand, a fuel injection nozzle (not shown) is provided upright on a substantially central axis of a cylinder bore of each cylinder of the cylinder head 11, and a mounting boss 15 of the fuel injection nozzle is integrally formed when the cylinder head 11 is cast.

A cooling water passage 16 is formed between each throat portion of each of the exhaust ports 14A and 14B and the mounting boss 15 of the fuel injection nozzle. Here, in a direct injection diesel engine having two intake valves, in order to improve combustion performance,
In order to form a strong swirling flow (swirl flow) in the lateral direction of the cylinder by the intake air, it is necessary to have an intake port shape (helical, tangential) that is asymmetrically arranged with respect to the cylinder.

Accordingly, the exhaust ports also have an asymmetric arrangement. In such a configuration, the port cylinder head 11
The port toward the throat recessed with respect to the end face of the side wall has a length from the center of the cylinder to a position further advanced. For this reason, in the method of inserting the port forming core at the time of casting of the cylinder head 11 into the cooling water jacket forming core 20 (see FIG. 2) at right angles to the cylinder longitudinal direction, the exhaust port It is difficult to form a cooling water passage between the throat portion and the mounting boss of the fuel injection nozzle (all portions where a cooling water passage is to be formed due to the insertion trajectory of the port forming core in the recessed port throat portion) It becomes useless).

Therefore, in the present configuration, the insertion trajectory of the exhaust port forming core 26 (see FIG. 2) is curved while bypassing the nozzle hole 15A of the fuel injection nozzle as shown in FIG. 1A. The cooling water passage 16 can be formed around the nozzle hole 15A. In this case, in order to secure the insertion space for the exhaust port forming core 26, the outer wall of the exhaust port 14A and the outer wall of the intake port 12 of the cylinder adjacent to the exhaust port 14A are partially shared (see FIGS. 1, 3 and 4). Common outer wall 17).

Thus, the exhaust port forming core 26 is formed.
Can be inserted so as to form a curved insertion trajectory while bypassing the nozzle hole 15A by utilizing a part of the space where the intake port forming core 27 (see FIG. 2) exists.
As shown in FIG. 5, the exhaust port 14A at the end of the cylinder head 11 has no adjacent intake ports 12 and 13, so that the exhaust port forming core 2 is not provided.
In order to secure the insertion space of No. 6, a part of the outer wall is formed thick (thick portion 11A).

Therefore, the insertion order of the port forming core is as follows.
Exhaust port forming core 26, intake port forming core 2
The order is 7, 28. In addition, since the heat load of the intake ports 12 and 13 is smaller than that of the exhaust ports 14A and 14B,
No cooling water jacket is required on top of it. Therefore,
Cooling water jackets are provided at upper and lower portions of the exhaust ports 14A and 14B and at lower portions of the intake ports 12 and 13, respectively.
The cooling water passage around the mounting boss 15 of the fuel injection nozzle connects the upper and lower cooling water jackets.

Thus, the intake port forming core 27,
As shown in FIG. 2, it is possible to set 28 from above the cooling water jacket forming core 20, and it is possible to improve the setting property and the productivity. On the other hand, since the exhaust ports 14A and 14B are shaped to cross the cylinder head 11, their entire lengths are long.

Therefore, when the cooling water passages are to be provided above and below the exhaust ports 14A and 14B, the exhaust port forming cores 26 are arranged in the horizontal direction with respect to the exhaust port forming core arrangement space of the water jacket forming core 20. Need to be inserted.
Therefore, in this configuration, the exhaust port forming core 26
Is a parting line 3 between the core 26 and the cylinder head lower mold 29.
The height T3 of the exhaust port 14 (the split surface between the exhaust port forming core 26 and the cylinder head lower mold 29 at the throat portions of the exhaust ports 14A and 14B) is increased to form the exhaust port 1
The overall height of 4A and 14B is reduced, the setability of the exhaust port forming core 26 is improved, and the width of the upper and lower cooling water passages is maximized.

In this case, as shown in FIG.
And the height of the upper surface of the cooling water passage 10B between the throat portions of the exhaust ports 14A, 14B or the exhaust ports 14A, 14B.
A higher dimension T1 of the upper height of the cooling water jacket 10A at the bottom of B, a thickness T2 of the upper wall of the exhaust ports 14A and 14B, a height T4 of the port positioning tenon 29A of the cylinder head lower mold 29, and a margin. Various dimensions are set so that the relationship with the margin Δ is represented by the following equation.

T3> T1 + T4-T2-Δ In such a configuration, the exhaust port forming core 26 is raised while using the space of the cooling water jacket forming core 20 which is the upper wall of the exhaust ports 14A and 14B. The core 20 for forming the jacket is inserted into the insertion portion 19 (see FIG. 4) which is a space for disposing the core for forming the exhaust port.

Thus, the exhaust port forming core 26 is formed.
Is set at a predetermined position by clearing a portion 22 (see FIG. 7) corresponding to a water jacket portion below the cooling water jacket forming core 20 and a positioning tenon 29A provided on the upper surface of the throat portion of the cylinder head lower mold 29. Is done. still,
The allowance Δ takes into account the dimensional variation of the core and the position balance at the time of setting.

The throat portions of the exhaust ports 14A and 14B are formed in a substantially cylindrical shape, and are formed by a core portion 29B which is formed to extend substantially in a substantially cylindrical shape from the lower cylinder head mold 29, and is machined by a throat cutter or the like. Finishes the shape. 4 and 7, 18
A, 18B are insertion portions of the intake port forming cores 27, 28 in the cooling water jacket forming core 20, and 23 are
An intake port lower cooling water jacket forming portion, 25 is an exhaust port lower cooling water jacket forming portion, and 24 is a vertical cooling jacket communication passage forming portion.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of one embodiment of a cylinder head of a direct injection diesel engine according to the present invention.

FIG. 2 is a perspective view showing a method for setting a port forming core to a cooling jacket forming core of the cylinder head.

FIG. 3 is a longitudinal sectional view of an exhaust port forming portion of the jacket according to the first embodiment.

FIG. 4 is a perspective view of a cooling jacket forming core of the cylinder head.

FIG. 5 is a cross-sectional view of the cylinder head.

FIG. 6 is a vertical cross-sectional view of the cylinder head.

FIG. 7 is a perspective view from below of a cooling jacket forming core of the cylinder head.

FIG. 8 is a cross-sectional view of a conventional cylinder head.

FIG. 9 is a cross-sectional view of a conventional cylinder head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Cylinder head 11A Thick part 12,13 Intake port 14,14A, 14B Exhaust port 15 Boss for mounting fuel injection nozzle 16 Cooling water passage 17 Common outer wall 20 Core for forming cooling water jacket 26 Core for forming exhaust port 27 , 28 Inlet port forming core 30 Parting line

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location F02B 31/02 F02B 31/02 H F02F 1/24 F02F 1/24 B J1 / 42 1/42 D F G K F02M 61/14 310 F02M 61/14 310D

Claims (7)

[Claims] 1. A cylinder head made of casting is provided with two intake valves and two exhaust valves for each cylinder, and the cylinder head is provided with four intake and exhaust valves which are opened and closed by the four valves for each cylinder. A direct-injection diesel engine having ports and two intake valves for each cylinder and two exhaust valves arranged in parallel in a direction substantially orthogonal to the central axis direction of the crankshaft. The outer wall of each intake port extending rearward with respect to the intake port opening position on the cylinder head side wall of the adjacent cylinder and the outer wall of each exhaust port adjacent to the intake port are connected at their closest point to share the port outer wall. And the outer wall of the exhaust port located on one end wall side in the cylinder row direction of the cylinder head is formed to be thicker than the outer wall of the other part. A fuel injection nozzle is provided upright on a substantially central axis of a cylinder bore of each cylinder of the cylinder head, and a boss for mounting the fuel injection nozzle is integrally formed with the cylinder head. Each throat portion of the two exhaust ports and the fuel A cylinder head for a direct injection diesel engine, wherein a cooling water passage is formed between the injection nozzle and a mounting boss of the injection nozzle. 2. The two intake ports are respectively opened as a helical port and a tangential port on one side wall surface of a cylinder head and communicate with an intake manifold.
The two exhaust ports are formed as a single exhaust port where the flow from the throat portion of each port joins in the middle, and is opened to the other side wall surface of the cylinder head and communicates with an exhaust manifold. 2. The cylinder head of the direct injection diesel engine according to 1. 3. The cylinder head for a direct injection diesel engine according to claim 1, wherein the cylinder head is made of aluminum casting. 4. The cylinder head of a direct injection diesel engine according to claim 1, wherein said diesel engine is a DOHC type engine. 5. A cooling water jacket is provided at each of an upper portion and a lower portion of the exhaust port and a lower portion of the intake port, and the upper and lower cooling water jackets are formed by the cooling water passage around a mounting boss of the fuel injection nozzle. The cylinder head of a direct injection diesel engine according to any one of claims 1 to 4, characterized in that: 6. A casting mold for casting a cylinder head of a direct-injection diesel engine according to claim 5, wherein a split surface T3 between an exhaust port forming core and a lower cylinder head mold at a throat portion of the exhaust port is formed by an exhaust port. Of the upper surface of the cooling water passage between the throat portions or the upper height of the cooling water jacket below the exhaust port, the upper dimension T1 of the exhaust port, the wall thickness T2 of the upper portion of the exhaust port, and a tenon for positioning the lower port of the cylinder head lower die. A cylinder head casting mold for a direct-injection diesel engine, which is set so as to have the following relationship with the height T4 and the allowance Δ. T3> T1 + T4-T2-Δ 7. A cylinder head made of casting is provided with two intake valves and two exhaust valves for each cylinder, and the cylinder head is provided with four intake and exhaust valves which are opened and closed by the four valves for each cylinder. A direct-injection diesel engine having ports and two intake valves for each cylinder and two exhaust valves arranged in parallel in a direction substantially orthogonal to the central axis direction of the crankshaft. The cooling water passage is formed around the nozzle hole by bending the insertion trajectory of the exhaust port forming core used for casting into the cooling water jacket forming core while bypassing the nozzle hole of the fuel injection nozzle. A cylinder head of a direct injection diesel engine, characterized in that: