JPS62282747A - Expendable pattern for casting cylinder head for internal combustion engine - Google Patents

Abstract

PURPOSE:To eliminate the volumetric change and shape change of a combustion chamber by dividing an expendable pattern for casting a cylinder head by the parting lines extending along the base of water jackets positioned right above the combustion chamber of the cylinder head. CONSTITUTION: The cylinder head 11 is set with the parting line D, E, F, G, H extending from a suction side lateral face 22 toward an exhaust side lateral face 23 along the center line of a suction port 20 and an exhaust port 21. The parting line D positioned right above the combustion chamber 18 is so set as to extend along the base of water jackets 19a, 19b, 19c, 19d. The respective expendable patterns corresponding to blocks 101, 102, 103, 104, 105, 106 divided in the positions of the parting line D, E, F, G, H are then formed and are united to one body by an adhesive agent. The volumetric change and shape change relating to the combstion chamber of the cylinder head are thereby eliminated.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a fugitive model for casting that becomes a gaseous state and disappears due to the action of the molten metal that has been cast, and particularly relates to The present invention relates to a divided structure of a fugitive casting model used for casting engine cylinder heads.

[Conventional technology]

Traditionally, coreless (coreless) castings are produced by making an actual model using a material that becomes gaseous and disappearing due to the action of molten metal, and then pouring molten metal into this model while it is buried in sand.
Core Less) casting method is known (Special Publication Act 5
2-14206).

When manufacturing a cylinder head using a fugitive model (generally, expanded polystyrene is used as the fugitive model, henceforth referred to as a poly model), it is difficult to make the poly model in one piece due to the complicated shape of the cylinder head. , it is necessary to create a poly model by dividing it. Therefore, a plurality of parting lines (dividing lines) extending in the horizontal direction are usually set on the printing head, and the poly model is divided into a plurality of pieces by these parting lines.

The polygon models, which have been divided into multiple pieces, are then glued together using adhesive, but if the glue drips from the bonding surface, the dripping adhesive will disappear when poured and be replaced by molten metal, causing the adhesive to drip from the bonding surface. , causing the adhesion of waste meat. Therefore, it is desirable to make the parting line horizontal because it prevents the adhesive from dripping and improves productivity.

[Problem that the invention seeks to solve]

However, if an attempt is made to completely horizontally divide the image as described above, there is a possibility that performance will be disadvantageous. In other words, if you try to horizontally divide the parts, the joint surface may have to pass through the combustion chamber, and if the adhesive protrudes or the model is misaligned even slightly, the volume and shape of the combustion chamber will change. Therefore, there is a problem in that non-king and combustion variations in each cylinder occur, which significantly deteriorates engine performance.

In order to solve the above-mentioned problems, the present invention sets the dividing plane of the fugitive model at an appropriate position and makes it as horizontal as possible, thereby eliminating changes in volume and shape of the combustion chamber due to misalignment of the fugitive model. The aim is to further improve engine performance.

[Means for Solving the Problems] A fugitive model for casting a cylinder head F for an internal combustion engine according to the present invention in accordance with this object is used for casting a cylinder head of an internal combustion engine, and is used to cast molten metal. A fugitive model for casting a cylinder head for an internal combustion engine that becomes a gas state and disappears due to the action of Consists of parts divided by parting lines.

[Effect]

In the fugitive model for casting a cylinder head for an internal combustion engine configured in this way, the fugitive model is divided along the bottom surface of the water jacket located directly above the combustion chamber, so the combustion chamber itself is not divided. It never happens. In other words, since the fugitive model is divided into shapes along the top surface of the combustion chamber wall, the inner wall of the combustion chamber can be formed in the same shape as the model, regardless of the effects of misalignment of the model or spillage of adhesive. be done. Therefore, there are no steps or cracks that occur on the combustion chamber wall due to positional deviation, and the volume of the combustion chamber on the cylinder head side is maintained at a predetermined value. Therefore, the occurrence of knocking and variations in combustion among the cylinders are eliminated, and engine performance is improved.

〔Example〕

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a fugitive model for casting a cylinder head for an internal combustion engine according to the present invention will be described below with reference to the drawings.

In this embodiment, the shape and division structure of the fugitive model will be explained using a seven-ring head in a completed state, and the actual fugitive model used for casting the throat into the cylinder is not shown. Furthermore, expanded polystyrene is used as the fugitive model material.

1 to 5 show the throat of a cylinder cast using a fugitive model (hereinafter referred to as a poly model) of a cylinder head for an internal combustion engine according to an embodiment of the present invention,
In particular, it shows the cylinder head of a six-cylinder DOHC gasoline engine that has been machined after being cast.

FIG. 5 shows the entire cylinder head.

In the figure, 11 indicates a cylinder head, and 12 indicates a plug tube to which a spark plug is attached. A pulp lifter guide 13 on the intake side is provided on the right side of the figure with the plug tube 12 as the center, and a pulp lifter guide 14 on the exhaust side is provided on the left side.

Furthermore, cam journal portions 15a and 15b are provided on the left and right sides of each plug tube 12, respectively. In addition,
In the figure, 16 indicates a tight plug in the sand removal hole.

FIG. 1 shows a cross section taken along line I-1 in FIG.

In the figure, 17 indicates the lower surface of the cylinder head.

A mountain-shaped combustion chamber 18 is formed on the lower surface 17 side of the cylinder head, and water jackets 19a and 19b are provided diagonally above the combustion chamber 18. Above the water jackets 19a and 19b, an intake port 20 and an exhaust port 21 are provided on the left and right sides of the axis 10. One side of the intake port 20 is open to the combustion chamber 18 , and the other side is opened to the intake side side surface 22 of the cylinder head 11 . One of the exhaust ports 21 is connected to the combustion chamber 18
The other side is opened at the exhaust-side side surface 23 of the cylinder head 11. A water jacket 19C is located directly above the exhaust port 21.

Valve stem holes 24 and 25 are provided above the combustion chamber 18, into which valve stems for intake and exhaust pulp (not shown) are inserted. Below the valve stem hole 24 is the intake boat 2
0, and the lower part of the valve stem hole 25 is opened to the exhaust port 21. Above the valve stem hole 24.25, the above-mentioned valve lifter guide 13.14 is provided. The upper part of the valve stem hole 24 opens toward the center of the valve lifter guide 13 , and the upper part of the valve stem hole 25 opens toward the center of the valve lifter guide 14 . Spring grooves 24a and 25a for supporting valve coil springs (paths shown) are provided on the upper end surface side of the valve stem hole 24, 25.

Between the valve stem hole 24 and the valve stem hole 25,
A water jacket 19d extending toward the combustion chamber 18 is provided. Valve lifter guide 13. ], 4 are provided with cam journal parts i5a, 15b that support the camshaft (path shown).

The above-mentioned cam journal parts 15a, 15b, valve lifter guide 13.14, and valve stem hole 24°2
5 are arranged in a straight line. In addition, in the figure, 2
6 indicates a blow-by gas passage, and the blow-by gas passage 26 is connected to the intake boat 20 and to the cylinder Rad IX.
It is provided on the exhaust side side surface 23 side of the.

The cylinder head 11 integrally constructed in this way is cast using a poly mold made with the same dimensions as the cylinder head 11. The poly model has a split structure due to the casting process, and the split positions of the poly model are set by parting lines, which will be described later. That is, in this example, the poly model is divided into 6 parts by the parting lines E, F, G, and H.
It is divided.

In FIG. 1, the parting line extends from the intake-side side surface 22 of the cylinder Rad 11 along the bottom surface of the blow-by gas passage 26, and extends in the horizontal direction to the bottom surface of the water jacket 19a. From the desk, the parting line extends along the bottom of the chevron-shaped water jacket located directly above the combustion chamber 18, and extends from the bottom of the chevron-shaped water jacket to the cylinder through the bottom of the water jacket 19b. It extends in the horizontal direction to the exhaust side side surface 23 of 11.

The parting line E extends from the intake side side surface 22 of the cylinder Rad 11 along the center line of the intake boat 20, and one end thereof is
It is perpendicular to the parting line. The parting line E extends along the parting line along the upper part of the combustion chamber 18, and
Extending along the center line of the exhaust port 21 from the position of the exhaust port 21 opening to the exhaust side surface 2 of the cylinder head 11
It has reached 3.

Giving up &? IF is above the intake boat 20 and descends from the intake side side surface 22 of the cylinder head 11 along the curvature of the intake boat 20, and is below the spring groove 24a and approximately midway in the vertical direction of the valve stem hole 24. It is moving horizontally. Then, as it is, the valve stem hole 24, the vicinity of the top surface of the water jacket 19d, the valve stem hole 25
, extending across the water jacket 19c to the exhaust side surface 23 of the cylinder 11.

A parting line G extends horizontally from a portion located on the intake side side surface 22 of the cylinder head 11 and between the valve stem hole 24 and the valve lifter guide 13 to the valve stem hole 24.
．． 25 and extends in the direction of the exhaust-side side surface 23 of the cylinder head 11 .

Giving up &? IH is the intake side side surface 22 of the cylinder head 11, and from the part located between the valve lifter guide 13 and the cam journal 15a, the cylinder head 1 is horizontally grazed over the tops of the valve lifter guides 13 and 14.
1 extends in the direction of the exhaust side surface 23 of FIG.

Therefore, if the poly model is divided by the parting line in Figure 1, the poly model will be divided into blocks 101, 102, 103
, 104□tos, 106.

FIG. 2 shows a cross section of the cylinder head taken along the line -u in FIG. 5. In the figure, 18 indicates a combustion chamber, and a plug tube 12 into which a spark plug (path shown) is inserted is formed directly above the combustion chamber 18. The plug tube 12 extends from the upper surface 41 of the cylinder rad 11 to the combustion chamber 18.
The lower part of the plug tube 12 is a plug neck portion 12a. The lower part of the plug tube 12 has a thinned cylindrical shape, and its lower end is integrally connected to the combustion chamber wall 43.

A water jacket 1 is installed around the outer periphery of the plug tube 12.
9e is formed. The water jacket 19e is
It is surrounded by the plug tube 12, cylinder head members 44a and 44b forming an intake boat 21 and an exhaust boat 22, and a combustion chamber wall 43 forming a part of the combustion chamber 18. As a result, especially the upper wall 43 of the combustion chamber 18,
It is possible to contact the water jacket 19e over a wide area.

At approximately the midpoint in the vertical direction of the plug tube 12 and on the outer periphery of the plug tube 12, water sinks 7 f and 19 g each having a parallelogram cross-section are provided. Above the water jackets 19f and 19g,
Cam journal parts 15a and 15b are provided. In addition, in the figure, 26 indicates a blow-by gas passage, and 4
5 is an insertion hole into which a fuel injection valve (path shown) is inserted.

In the cross section of the cylinder head in FIG. 2, the parting line is horizontal from the intake side side surface 22 of the cylinder head 11 to the bottom surface of the water jacket 19e, passing through the vicinity of the bottom surface of the blow-by gas passage 26, as in FIG. extending in the direction. Then, the parting line extends along the upper surface of the combustion chamber wall 43, that is, the bottom surface of the walk shaker 7) 19e, and extends from the point where it crosses the plug threaded portion 12a and ends down the bottom surface of the water jacket 196 to the cylinder head 1.
It extends horizontally toward the exhaust side side surface 23 of 1.

The parting line E extends from the intake-side side surface 22 of the cylinder head 11 along the center line of the intake boat 20, and extends to reach the bottom surface of the water jacket 19e. Also,
The parting line E on the exhaust boat 21 side also extends from the bottom surface of the water jacket 19e along the center line of the exhaust boat 21 toward the exhaust side side surface 23 of the cylinder head 11.

The parting line F extends horizontally above the intake bow 20 from the intake side side surface 22 of the cylinder head 11 toward the plug tube j2. Further, the parting line F is located at the upper part of the exhaust boat 21, and this part is horizontal.

The parting line G is located above the above parting line F, extends horizontally from the intake side side surface 22 of the cylinder Rad 11, crosses the water jacket 19f, the plug tube 12, and the water jacket 19g, and connects to the exhaust side of the cylinder head 11. It extends toward the side surface 23. Note that a part of the parting line G on the outer periphery of the plug tube 12 extends downward and also stands up. That is, the joint portion of the polygon model in this part has a fitting structure, so that the polymorphism model can be easily aligned and the positioning accuracy is improved.

The parting line H extends horizontally from the intake side side surface 22 of the cylinder head 11, and the parting line H at this position
The height is equal to the height of the parting line H shown in FIG. When the parting line H comes directly under the cam journal portion +5a, it rises, extends slightly horizontally, and then falls again, and continues horizontally at the same level as the starting point. and,
When the parting line H comes directly under the cam journal part 15b, it rises up a step and extends horizontally in the same way as described above, and then goes down again and returns to the original level to reach the exhaust side surface 23 of the cylinder rad 11.
extending towards. That is, the parting line H rises in a convex shape only directly below the cam journal parts 15a and 15b, and in the poly model, this part has a fitting structure. This facilitates positioning of the polygon model and ensures a predetermined positioning accuracy.

FIG. 3 shows a cross section taken along the line ■-■ in FIG.

In the figure, reference numeral 31 indicates a current plate that controls the flow direction of cooling water within the water jacket 19.

The current plate 31 has a rhombic shape that is elongated in the flow direction, and a recess 31a is formed in the current plate 31.

This reduces weight and improves cooling effectiveness.

On the upstream and downstream sides of the baffle plate 31, ribs 32. , 33.34°3
5 is provided. Moreover, a tight plug boss 36 which is a sand removal hole is provided above the current plate 31, and this tight plug boss 36 is provided with ribs 37 and 38 along the flow direction of the cooling water.

In the cross section of the cylinder head 11 shown in FIG. 3, the parting lines E, F, G, and H are set as follows. First, the lowermost parting line extends along the bottom surface of the water jacket 19 from below the intake manifold mounting screw hole 39 on the intake side side surface 22 of the cylinder head 11, and continues toward the exhaust side side surface 23. It is extending.

The parting line E extends obliquely downward from above the intake malhold mounting screw hole 39 on the intake side side surface 22 of the cylinder head 11 and reaches between the lip 32 and the rib 33.

The parting line E further extends obliquely downward from this position, passes between the lip 34 and the rib 35, and extends almost horizontally in the direction of the exhaust-side side surface 23 of the cylinder head 11.

A parting line F extends from the intake side side surface 22 of the cylinder head 11 and from directly above the above-mentioned parting line vAE to the tight plug boss 3.
6 and extends horizontally toward the cylinder head 11.
It extends in the direction of the exhaust side surface 23.

The positions of the parting lines G and H in FIG. 3 are set at the same level as in FIG. 1 and extend completely horizontally.

FIG. 4 shows the front side of the cylinder head as seen from the direction of line IV--IV in FIG. In the figure, numeral 51 indicates a tight plug for filling holes for removing sand, and tight plug 5
1 is located approximately at the center of the front side of the cylinder head 11. Cam journal portions 15a and 15b are located on the top side of the cylinder head 11, respectively. A timing cover mounting seat 52 is formed on the exhaust side side surface 23 (ll!l) of the cylinder head 11, and a timing cover mounting seat 52 is formed near the tight plug 51 for filling the sand removal hole. Timing cover mounting seat 5
3 is formed.

In FIG. 7, parting lines E, F, G.

The position of H is as follows. The parting line is located between the cylinder head lower surface 17 and the tight plug 51, and extends horizontally from the intake side surface 22 of the cylinder head 11 toward the exhaust side surface 23 of the Rad 11 toward the cylinder.

A parting line E extends from the intake side side surface 22 of the cylinder head 11 and from diagonally above the tight plug 51.
Cross the center of rad 1 and go down to the cylinder.
It extends in the direction of the exhaust side side surface 23 of No. 1 .

The parting line F is located at the upper part of the tight plug 51 and extends horizontally from directly above the parting line E on the intake side side surface 22 of the cylinder head 11 toward the exhaust side side surface 23 of the Rad 11 into the cylinder.

The parting line G is located above the parting line F, and extends horizontally from the intake-side side surface 22 of the cylinder Radar 11 toward the exhaust-side side surface 23 of the cylinder Radar 11.

The parting line H is located directly below the cam journal portions 15a and 15b, and is located directly below the intake side surface 22 of the Rad 11 to the cylinder.
It extends horizontally from the cylinder to the exhaust side surface 23 of the Rad 11, but is partially curved toward the upper surface of the cylinder head between the cam journal portion 15a and the cam journal portion 15b.

In addition, in this embodiment, five parting lines are set on the cylinder head 11, and the poly model corresponding to these is divided into six parts. , the degree of freedom in design increases and it becomes possible to obtain a cylinder head structure with excellent functionality. Further, the present invention is applicable not only to gasoline engines but also to diesel engines.

Next, the operation of the above-mentioned fugitive model for casting a cylinder head for an internal combustion engine will be explained.

As described above, the cylinder head 11 has a parting line extending from the intake side side surface 22 of the cylinder head 11 toward the exhaust side side surface 23 of the cylinder head 11.

E, F, G, and H are set, and the poly model used for casting the cylinder head 11 is divided into six parts by these parting lines. The polygon model divided into six parts is accurately aligned, and the joining surfaces (parting lines) of the polymorphism model are adhered and tightly attached with an adhesive.

In FIG. 1 and FIG. 2, the inner wall 18a of the combustion chamber 18
A block 101 is joined to a block 102 that forms part of the water jacket, intake boat 20, and exhaust boat 21. The joint surfaces (parting line D) between the block 101 and the block 102 are the water jackets 19a, 19b, 19d, 19
e, and since these bottom surfaces are the upper surfaces of the combustion chamber wall 43, the dividing plane is formed along the upper surface of the combustion chamber wall 43. That is, the combustion chamber 18 is no longer divided by the dividing plane (parting line D),
Even if the alignment of the blocks 101 and 102 is misaligned when they are glued together, the combustion chamber 1 on the Rad 11 side to the cylinder
8 is prevented from changing in shape or volume.

Therefore, if the above-mentioned split structure is used, the combustion chamber 1
No hot spots (high-temperature areas caused by steps, cracks, etc.) are generated on the inner wall 18a of the engine 8, preventing non-king, and maintaining the same volume of each cylinder, preventing variations in combustion among the cylinders. Ru.

In addition, other parting lines other than parting line E are on the intake side side surface 2.
2 toward the exhaust side surface 23, most of the bonding surfaces of the polygon model are horizontal surfaces, and dripping of the adhesive from the bonding surfaces is prevented.

Therefore, the occurrence of cracks and the like due to adhesive dripping is eliminated, and the dimensional accuracy of the cylinder head itself is maintained.

[Effects of the Invention] As explained above, when using the fugitive model for casting a cylinder head for an internal combustion engine of the present invention, the fugitive model is placed on the bottom surface of the water jacket that is positioned directly above the combustion chamber wall of the cylinder head. Since the parts are divided by cutting strips that extend along the sides, there is a risk of unevenness or cracks due to poor alignment of the model or adhesive extrusion, and the shape of the combustion chamber wall on the cylinder head side is maintained at the specified shape. be done. As a result, changes in volume and shape of the combustion chamber are prevented, and non-king and variations in combustion among the cylinders can be prevented. Therefore, the output of the engine can be further increased.

Further, by forming the bonding surface of the fugitive model to be a horizontal surface, it is possible to prevent the adhesive from dripping or protruding, thereby achieving the effect of preventing the occurrence of flakes.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a cylinder head manufactured by a fugitive model for casting a cylinder head for an internal combustion engine according to an embodiment of the present invention, and is a sectional view taken along line I-1 in FIG. 5. A cross-sectional view taken along line nn in Fig. 5, Fig. 3 shows the
A cross-sectional view along the line ■-■ in the figure, Figure 4 is Tl/- of Figure 5.
FIG. 5 is a plan view of the entire cylinder head of FIG. 1, which is a view taken from the direction of the rV line. 11......Cylinder head 18......Combustion chambers 19a, 19b, 19d, 19e- ---
−・Water jacket 43・・・・・・・・・・・・・・・ Combustion chamber wall, B, F, G, H・・・・・・・・・・・・line 1
01, 102.103.104.105.106...
...Block patent for a cylinder head in a DOHC engine divided by a parting line Applicant Toyota Motor Corporation Figure 3 Figure 4

Claims (1)

[Claims] (1) In a fugitive model for casting a cylinder head for an internal combustion engine, which is used to cast a cylinder head for an internal combustion engine and disappears by turning into a gaseous state due to the action of the molten metal that has been cast, the fugitive model is A fugitive model for casting a cylinder head for an internal combustion engine, characterized in that the model is divided by a parting line extending along the bottom surface of a water jacket located directly above a combustion chamber wall of the cylinder head.