JPH0780034B2 - Disappearance model for casting cylinder heads for internal combustion engines. - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an extinguishing model for casting, which disappears in a gas state by the action of cast molten metal, and particularly casts a cylinder head for an internal combustion engine. The present invention relates to a divided structure of a vanishing model for casting used in the.

[Prior Art] Conventionally, a coreless (cast) product is manufactured by making a physical model with a material that disappears in a gas state due to the action of molten metal, and pouring the molten metal while the model is buried in sand. Core Less) Casting method is known (Japanese Patent Publication Sho 52-14206)
Issue).

When manufacturing a cylinder head with an extinguishing model (usually referred to as a poly model because expanded polystyrene is used as the extinguishing model), it is difficult to make the poly model integrally because the shape of the cylinder head is complicated. , It is necessary to divide and make a poly model. Therefore, a plurality of parting lines (dividing lines) extending in the horizontal direction are usually set on the cylinder head, and the poly model is divided into a plurality of parts by the parting lines.

The poly model divided into a plurality of pieces is pasted with an adhesive, but when the adhesive drips from the pasting surface, the adhesive dripping during pouring disappears due to the molten metal and replaces it with molten metal. Causes adhesion of meat. Therefore, it is desirable to make the parting line horizontal so as to prevent the adhesive from sagging and from the viewpoint of productivity.

[Problems to be solved by the invention]

However, if the horizontal division is attempted completely, there is a possibility that the performance may be disadvantageous. In other words, if only horizontal division is attempted, the joint surface may have to pass through the combustion chamber, and if the protrusion of the adhesive or the misalignment of the model is a little, the volume or shape of the combustion chamber changes.
Therefore, there is a problem that knocking and variations in combustion in each cylinder occur, and engine performance is significantly deteriorated.

In order to solve the above problems, the present invention eliminates the volume change and shape change of the combustion chamber due to the misalignment of the fugitive model by setting the dividing surface of the fugitive model to an appropriate position and making it as horizontal as possible. The purpose is to further improve engine performance.

[Means for solving problems]

The extinguishing model for casting a cylinder head for an internal combustion engine of the present invention which achieves this object is used for casting a cylinder head of an internal combustion engine, and disappears in a gas state by the action of the cast molten metal. A vanishable model for casting a cylinder head for an internal combustion engine, the vanishable model being divided by a parting line extending along a bottom surface of a water jacket located immediately above a wall of a combustion chamber of the cylinder head.

[Action]

In the vanishing model for casting of the cylinder head for an internal combustion engine configured as described above, the vanishing model is divided along the bottom surface of the water jacket located immediately above the combustion chamber, and thus the combustion chamber itself is divided. There is no such thing. In other words, the extinguishing model is divided into shapes along the upper surface of the combustion chamber wall, so the inner wall of the combustion chamber is formed in the same shape as the model, despite the misalignment of the model and the protrusion of adhesive. To be done. Therefore, there is no step or burr generated on the inner wall of the combustion chamber due to the displacement, and the volume of the combustion chamber on the cylinder head side is maintained at a predetermined value. Therefore, occurrence of knocking and variation in combustion in each cylinder are suppressed, and engine performance is improved.

〔Example〕

Hereinafter, preferred embodiments of the fugitive model for casting of a cylinder head for an internal combustion engine according to the present invention will be described with reference to the drawings.

In the present embodiment, the shape and division structure of the fugitive model will be described based on the completed cylinder head, and the actual fugitive model used for casting the cylinder head is not shown. Further, expanded polystyrene is used as the disappearing model material.

1 to 5 show a cylinder head cast using a vanishing 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. 1 shows a machined 6-cylinder DOHC gasoline engine cylinder head.

FIG. 5 shows the entire cylinder head. 11 in the figure
Indicates a cylinder head, and 12 indicates a plug tube to which a spark plug is attached. The intake side valve lifter guide is located on the right side of the engine with the straight line connecting the plug tubes 12 as the center of the engine in the left-right direction.
13 is provided, and an exhaust side valve lifter guide 14 is provided on the left side. Further, cam journal portions 15a and 15b are provided on the right and left of each plug tube 12, respectively. In the figure, 16 indicates a tight plug having a second hole.

FIG. 1 shows a cross section taken along the line II of FIG. In the drawing, 17 indicates the lower surface of the cylinder head. A mountain-shaped combustion chamber 18 is formed on the side of the lower surface 17 of the cylinder head, and the water jacket 19a,
19b is provided. Above the water jackets 19a and 19b, an intake port 20 and an exhaust port 21 are provided on the right and left around the axis 10. One end of the intake port 20 is opened to the combustion chamber 18, and the other end is opened to the intake side surface 22 of the cylinder head 11. One end of the exhaust port 21
It is opened to the combustion chamber 18, and the other end is opened to the exhaust side side surface 23 of the cylinder head 11. A water jacket 19c is located directly above the exhaust port 21.

Above the combustion chamber 18, there are provided valve stem holes 24 and 25 through which the valve stems of intake and exhaust valves (not shown) are inserted. The lower end of the valve stem hole 24 is opened to the intake port 20, and the lower end of the valve stem hole 25 is opened to the exhaust port 21. Valve lifter guides 13 and 14 are provided above the valve stem holes 24 and 25. The upper part of the valve stem hole 24 is open toward the center of the valve lifter guide 13, and the upper part of the valve stem hole 25 is the valve lifter guide.
It opens toward the center of 14. Valve stem hole 24,25
Spring grooves 24a and 25a for supporting a valve coil spring (not shown) are provided on the upper end surface side of the.

A water jacket 19d whose cross section extends toward the combustion chamber 18 is provided between the valve stem hole 24 and the valve stem hole 25. Diagonally above the valve lifter guides 13 and 14,
Cam journal portion 15 that supports a cam shaft (not shown)
a and 15b are provided. The cam journal portions 15a and 15b, the valve lifter guides 13 and 14, and the valve stem holes 24 and 25 are arranged in a straight line, respectively. Reference numeral 26 denotes a blow-by gas passage. The blow-by gas passage 26 is provided below the intake port 20 and near the intake side surface 22 of the cylinder head 11.

The integrated cylinder head 11 is a cylinder head.
Cast using a poly model made to the same dimensions as 11. The poly model has a divided structure due to the casting condition, and the dividing position of the poly model is set by a parting line described below. That is, in this embodiment, the poly model is divided into 6 by the parting lines D, E, F, G and H.

In FIG. 1, the parting line D extends in the horizontal direction from the intake side surface 22 of the cylinder head 11 near the bottom surface of the blow-by gas passage 26 to the bottom surface of the water jacket 19a. Then, the parting line D is such that the bottom surface located immediately above the combustion chamber 18 extends along the bottom surface of the mountain-shaped water jacket, and passes from the position below the bottom surface of the mountain-shaped water jacket through the bottom surface of the water jacket 19b to the cylinder head 11 It extends in the horizontal direction up to the exhaust side surface 23.

The parting line E extends from the intake side surface 22 of the cylinder head 11 along the center line of the intake port 20, and one end thereof is orthogonal to the parting line D. The parting line E extends along the parting line D in the upper portion of the combustion chamber 18, extends from the position of the exhaust port 21 opening to the combustion chamber 18 along the center line of the exhaust port 21, and forms the exhaust side surface of the cylinder head 11. It has reached 23.

The parting line F descends above the intake port 20 and from the intake side surface 22 of the cylinder head 11 along the curvature of the intake port 20, below the spring groove 24a, and in the valve stem hole 24.
It has moved to the horizontal parting line at approximately the middle of the vertical direction.
Then, the valve stem hole 24, the vicinity of the top surface of the water jacket 19d, the valve stem hole 25, the water jacket 19c, and the exhaust side surface 23 of the cylinder head 11 are extended as they are.

The parting line G is on the intake side surface 22 of the cylinder head 11 and horizontally from a portion located between the valve stem hole 24 and the valve lifter guide 13 and passes horizontally above the valve stem holes 24, 25 so that the cylinder head 11 extends. It extends to the exhaust side surface 23.

The parting line H is the intake-side side surface 22 of the cylinder head 11 and extends horizontally from the portion located between the valve lifter guide 13 and the cam journal 15a.
Extends to the exhaust side surface 23 of the cylinder head 11 with the top part of the cylinder shredded.

Therefore, if the poly model is divided by the parting line of FIG. 1, the poly model is divided into blocks 101, 102, 103, 104, 105, 10
Divided into 6.

FIG. 2 shows a cross section of the cylinder head taken along the line II-II in FIG. In the figure, 18 indicates a combustion chamber,
Directly above 18 is a plug tube 12 into which a spark plug (not shown) is inserted. The plug tube 12
It penetrates from the upper surface 41 of the cylinder head 11 to the combustion chamber 18, and the plug screw 12a
Are formed. The lower portion of the plug tube 12 has a thinned cylindrical shape, and the lower end thereof is integrally connected to the combustion chamber wall 43.

On the outside of the plug tube 12, a water jacket 19e
Are formed. The water jacket 19e is surrounded by the plug tube 12, cylinder head members 44a and 44b forming the intake port 20 and the exhaust port 21, and the combustion chamber wall 43 forming a part of the combustion chamber 18. As a result, in particular, the upper wall 43 of the combustion chamber 18 contacts the water jacket 19e with a large area.

Water jackets 19f and 19g each having a parallelogram cross section are provided at a substantially intermediate position in the vertical direction of the plug tube 12 and outside the plug tube 12. Above the water jackets 19f and 19g are cam journals 15a and 15b.
Is provided. In the figure, 26 indicates a blow-by gas passage, and 45 is an insertion hole into which a fuel injection valve (not shown) is inserted.

In the cross section of the cylinder head in FIG. 2, the parting line D
1 extends in the horizontal direction from the intake side surface 22 of the cylinder head 11 through the vicinity of the bottom surface of the blow-by gas passage 26 to the bottom surface of the water jacket 19e similarly to FIG. Then, the parting line D extends along the upper surface of the combustion chamber wall 43, that is, the bottom surface of the water jacket 19e, crosses the plug screw portion 12a, and finishes descending from the bottom surface of the water jacket 19e to the exhaust side of the cylinder head 11. Side 23
It extends horizontally toward.

The parting line E extends from the intake side surface 22 of the cylinder head 11 along the center line of the intake port 20 and
It has reached the bottom of 19e. The parting line E on the exhaust port 21 side also extends from the bottom surface of the water jacket 19e along the center line of the exhaust port 21 to the exhaust side surface 23 of the cylinder head 11.

The parting line F extends substantially horizontally above the intake port 20 and from the intake side surface 22 of the cylinder head 11 toward the plug tube 12, and bends in the vertical direction near the plug tube 12 to the water jacket 19e. Further, the parting line F is located above the exhaust port 21, and that part is substantially horizontal.

The parting line G is located above the parting line F and extends horizontally from the intake-side side surface 22 of the cylinder head 11 to the water jacket 19f, the plug tube 12, and the water jacket 1.
It extends across 9g to the exhaust side surface 23 of the cylinder head 11. In addition, a part of the parting line G on the outer periphery of the plug tube 12 extends in a downward direction and rises again.
That is, the joining portion of this poly model has a fitting structure so that the poly model can be easily aligned and the positioning accuracy is improved.

The parting line H extends horizontally from the intake side surface 22 of the cylinder head 11, and the height of the parting line H at this position is equal to the height of the parting line H shown in FIG. When the parting line H is directly below the cam journal portion 15a, the parting line H rises, extends slightly in the horizontal direction, and then decreases again, and extends in the horizontal direction at the same level as the starting point. When the parting line H is located directly below the cam journal portion 15b, it rises in one direction and extends horizontally in the same manner as described above, and also descends and extends to the exhaust side surface 23 of the cylinder head 11 at the original level. That is, the parting line H is the cam journal portion 15a,
It rises in a convex shape only just under 15b, and this part has a mating structure in the poly model. This facilitates the positioning of the poly model and ensures a predetermined positioning accuracy.

FIG. 3 shows a cross section taken along the line III-III in FIG. In the figure, reference numeral 31 denotes a straightening vane that controls the flow direction of the cooling water in the water jacket 19. The current plate 31 has a rhombus shape elongated in the flow direction, and the current plate 31 has a recess.
31a is formed. Thereby, the weight reduction and the cooling effect are improved.

Ribs 32, 33, 34, 35 for controlling the flow direction of the cooling water are provided on the upstream side and the downstream side of the flow straightening plate 31 as described above. Further, a tight plug boss 36, which is a sand removing hole, is provided above the straightening vane 31.
Ribs 37, 38 are provided on the.

In the cross section of the cylinder head 11 shown in FIG. 3, the parting line D,
E, F, G, H are set as follows. First, the parting line D extends along the bottom surface of the water jacket 19 from the lower portion of the intake manifold mounting screw hole 39 on the intake side surface 22 of the cylinder head 11 and extends substantially horizontally to the exhaust side surface 23. There is.

The parting line E extends obliquely downward from the intake side surface 22 of the cylinder head 11 and above the intake malhold mounting screw hole 39, and reaches between the ribs 32 and 33. And
The parting line E extends further obliquely downward from this position and is a rib.
Passes between 34 and rib 35, and makes the cylinder head almost horizontal
11 extends to the exhaust side surface 23.

The parting line F extends horizontally from the portion on the intake side 22 of the cylinder head 11 and directly above the parting line E toward the tight plug boss 36, and extends as it is toward the exhaust side surface 23 of the cylinder head 11.

The positions of the parting lines G and H in FIG. 3 are set to the same level as in FIG. 1, and extend completely in the horizontal direction.

FIG. 4 shows the front side of the cylinder head viewed from the IV-IV line direction in FIG. In the figure, reference numeral 51 denotes a tight plug for filling a sand removing hole, and the tight plug 51 is located substantially at the center of the front side of the cylinder head 11.
On the top surface side of the cylinder head 11, the cam journal portion 15a,
15b are located respectively. A timing cover mounting seat 52 is formed on the exhaust side surface 23 side of the cylinder head 11, and in the vicinity of the tight plug 51 for filling the sand removal hole,
A timing cover mounting seat 53 is formed which extends in the vertical direction and is curved toward the tight plug 51.

In FIG. 4, the positions of the parting lines D, E, F, G, H are as follows. The parting line D is the lower surface of the cylinder head
Located between 17 and tight plug 51, cylinder head 11
Horizontally extending from the intake side surface 22 to the exhaust side surface 23 of the cylinder head 11.

The parting line E extends on the intake side surface 22 of the cylinder head 11 from diagonally above the tight plug 51, crosses the central portion of the tight plug 51, and goes down to the exhaust side surface 23 of the cylinder head 11.

The parting line F is located above the tight plug 51 and extends horizontally from a portion of the intake side surface 22 of the cylinder head 11 directly above the parting line E to the exhaust side surface 23 of the cylinder head 11.

The parting line G is located above the parting line F and extends horizontally from the intake side surface 22 of the cylinder head 11 to the exhaust side surface 23 of the cylinder head 11.

The parting line H is located immediately below the cam journal portions 15a and 15b, and extends horizontally from the intake side surface 22 of the cylinder head 11 to the exhaust side surface 23 of the cylinder head 11. Between the cam journal portion 15b and the cam journal portion 15b, a part is curved toward the upper surface side of the cylinder head.

In the present embodiment, five parting lines are set on the cylinder head 11 and the poly model corresponding to this is divided into six, but the poly model is not limited to six, and if the poly model is further divided into a large number. Thus, the degree of freedom in design is increased, and it becomes possible to obtain a functionally superior cylinder head structure. Further, the present invention is applicable not only to a gasoline engine but also to a diesel engine.

Next, the operation of the extinguishing model for casting the cylinder head for an internal combustion engine will be described.

As described above, the cylinder head 11 includes the intake side surface 22 of the cylinder head 11 to the exhaust side surface of the cylinder head 11.
A parting line D, E, F, G, H extending toward 23 is set, and the poly model used for casting the cylinder head 11 is divided into six parts by this parting line. The six-divided poly model is accurately aligned, and the joining surface (parting line) of the poly model is adhered and adhered with an adhesive.

1 and 2, a block 101 on which an inner wall surface 18a of a combustion chamber 18 is formed is a block that forms a water jacket and a part of an intake port 20 and an exhaust port 21.
Joined with 102. The joint surfaces of the blocks 101 and 102 (parting line D) are water jackets 19a, 19b, 19d, 19
e extends along the bottom surface of the combustion chamber wall 4
Since it is the upper surface of 3, the dividing surface is formed along the upper surface of the combustion chamber wall 43. That is, the combustion chamber 18 is not divided by the dividing surface (parting line D), and even if the alignment of the block 101 and the block 102 at the time of bonding is deviated, the shape and volume of the combustion chamber 18 on the cylinder head 11 side. Is prevented from changing.

Therefore, if the split structure as described above is adopted, the combustion chamber 18
No hot spots (high-temperature portions caused by steps, burrs, etc.) are generated on the inner wall surface 18a of the cylinder, knocking is prevented, the volume of each cylinder is maintained at the same volume, and variations in combustion of each cylinder are prevented. It

The other parting lines except the parting line E are the intake side surface 22.
Since it extends substantially horizontally from the exhaust side surface 23 to the exhaust side surface 23, most of the joining surface of the poly model is a horizontal surface, and the dripping of the adhesive from the joining surface is prevented. Therefore, the occurrence of burrs and the like due to the dripping of the adhesive is eliminated, and the dimensional accuracy of the cylinder head itself is maintained.

〔The invention's effect〕

According to the extinguishing model for casting of the cylinder head for an internal combustion engine of the present invention, the extinguishing model is divided by the parting line extending along the bottom surface of the water jacket located right above the combustion chamber wall of the cylinder head. Therefore, steps and burrs due to misalignment of the model and protrusion of the adhesive do not occur on the wall surface of the combustion chamber, and the shape of the combustion chamber wall on the cylinder head side is maintained at a predetermined shape. As a result, the volume and shape of the combustion chamber can be prevented from changing, and knocking and variations in combustion in each cylinder can be prevented. Therefore, the output of the engine can be further increased.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a cylinder head manufactured by an extinguishing model for casting a cylinder head for an internal combustion engine according to an embodiment of the present invention, which is a cross-sectional view taken along the line II of FIG. 5, and FIG. Sectional view taken along the line II-II in the figure, FIG. 3 is a sectional view taken along the line III-III in FIG. 5, and FIG. 4 is a view taken in the direction of the line IV-IV in FIG. 2 is a plan view of the entire cylinder head of FIG. 1. FIG. 11 …… Cylinder head 18 …… Combustion chamber 19a, 19b, 19d, 19e …… Water jacket 43 …… Combustion chamber wall D, E, F, G, H …… Partition line 101,102,103,104,105,106 …… DOHC engine divided by parting line Block of cylinder head in

Claims (1)

[Claims] 1. A vanishing model for casting of a cylinder head for an internal combustion engine, which is used for casting a cylinder head of an internal combustion engine and disappears in a gas state under the action of a molten metal that has been cast, said vanishing property. An extinguishable 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 immediately above the combustion chamber wall of the cylinder head.