JPH0771728B2 - Cylinder head and mold for cylinder head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to a cylinder head of an engine and a mold for manufacturing the cylinder head.

<Prior Art> As a method of manufacturing a cylinder head for a relatively low-cost mass production engine, die-cast molding in which a molten metal is injected under pressure tends to be frequently used.

On the other hand, in order to smooth the flow of intake air into the valve port,
It is desirable to make the inflow angle into the combustion chamber, that is, the angle between the axis of the intake passage and the axis of the valve port as large as possible.
The intake passage has a push rod insertion hole for transmitting the lift of the cam to the valve, a head tightening bolt insertion hole,
It must be installed at a position where it does not interfere with the cooling air or the cooling water passage.

<Problems to be Solved by the Invention> However, according to the die-cast molding described above, it is difficult to form the curved intake passage with the extraction core due to the mold opening direction of the die plate. There was no choice but to make it linear, and due to the dimensional restrictions of the cylinder head, the above-mentioned demand could not be satisfied. A mold device in which a curved tube is formed by using an arc-shaped core is disclosed in Japanese Utility Model Publication No. 56-26928. According to this, the mold opening operation of the die plate and the core removal are performed. The structure that links movements tends to be complicated,
Moreover, since it is practically impossible to bend it three-dimensionally, it is not sufficient to reduce the restriction on the positional relationship between the insertion hole of the push rod and the intake passage.

The present invention has been made to eliminate such inconvenience, and its main purpose is to form an intake passage that can smooth the intake flow flowing into the valve port and improve the layout flexibility. An object of the present invention is to provide a cylinder head of an engine having such a structure, and a mold device having a relatively simple structure for forming the intake passage.

[Configuration of the Invention] <Means for Solving the Problems> According to the present invention, the object is a cylinder head of an engine formed by die casting, in which combustion is performed from an opening on an outer surface of a Linda head. The cylinder head of the engine, and the cylinder head of the engine, characterized in that the intake passage extending to the vicinity of the intake port of the chamber has a spiral tubular shape wound around a linear axis with a constant curvature and a constant advance angle. And a core for forming an intake passage between the opening on the outer surface of the Linda head and the vicinity of the intake port of the combustion chamber, the core being a straight line with a constant curvature and a constant advance angle. The present invention is achieved by providing a mold for a cylinder head, which has a spiral shape wound around a shaft, and is rotatable about a central axis of the spiral and movable back and forth along the central axis. That.

<Operation> According to such a configuration, by appropriately determining the radius of curvature and the lead angle of the spiral, it is possible to give the intake passage a three-dimensional curved shape that can satisfy the engagement with other portions. . Moreover, since the core can be linearly pulled out along the central axis of the spiral by giving the core a rotation about the spiral axis, the structure of the mold is not complicated.

<Embodiment> A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

1 and 2 show a cylinder head 1 constructed according to the present invention. This cylinder head 1 is made by die-casting an aluminum alloy and has a top surface 2 to which a head cover (not shown) is fixed and a bottom surface 3 to be joined to an upper end surface of a cylinder block (not shown). , The respective surfaces 2 and 3 are formed flat.

On the lower surface of the cylinder head 1, a wedge-shaped combustion chamber 4 is recessed. An intake port 5 and an exhaust port 6 that are opened and closed by an intake valve and an exhaust valve (not shown) are arranged in parallel on the ceiling of the combustion chamber 4. A valve stem guide 7 is embedded above the intake port 5 and the exhaust port 6.

As shown in FIG. 2, a pair of head bolt holes 8 are located on the right of the intake / exhaust ports 5 and 6, and a pair of head bolt holes 9 are also located on the left of the ports. Has a pair of push rod insertion holes 10. And suck
A plug mounting hole 11 for screwing a tip portion of an ignition plug (not shown) is provided in a portion adjacent to both exhaust ports 5 and 6.

From the intake port 5 to the left side of the cylinder head 1,
An intake passage 12 is formed. The outside diameter of the intake passage 12 is increased as it goes outward, and the intake passage 12 is located between the pair of head bolt holes 9 located on the left side of FIG.
And a spiral shape having a constant curvature radius and a constant advance angle having a predetermined turning radius R and a pitch P and communicating with the outside by passing between the push rod insertion holes 10 forming a pair on the left side and the pair thereof. Is doing.

The exhaust passage 13 communicating from the exhaust port 6 to the outside extends in a direction substantially orthogonal to the intake passage 12. The exhaust passage 13 has a straight axis line and has a tapered shape whose outer diameter increases as it goes outward.

A plurality of cooling fins 14 are formed on the side wall of the cylinder head 1 to enhance cooling efficiency. And intake passage 5
An air passage 15 is formed by casting in a portion between the cylinder head lower surface 3 and the cylinder head so as to allow the cooling air to flow therethrough.

Now, in order to improve the combustion efficiency in the medium / low speed rotation range, make the intake passage longer so that the intake inertia can be used.
Moreover, it is advisable to increase the intake air inflow angle into the combustion chamber so that swirl is generated in the combustion chamber. Further, in order to make the intake passage longer and to make the cylinder head compact, it is preferable to extend the intake passage between the push rod insertion holes. However, in order to satisfy such a demand, it is necessary to give the intake passage a three-dimensional curved shape, which makes it virtually impossible to remove the core to form the intake passage portion. Was an obstacle to adopting die-cast molding for the production of.

Therefore, in the present invention, the intake passage 12 is formed so as to have a spiral shape with a constant curvature and a constant advance angle around an appropriate straight line C.
By forming the above, the projection shape of the intake passage 12 from the side surface is smoothly curved toward the intake port 5 (FIG. 1), and the projection shape seen from the upper surface is the intake port 5 And the opening 16 in the side wall of the cylinder head are offset from each other and pass through the portion between the head bolt hole 9 and the push rod insertion hole 10 (FIG. 2).

By making the shape of the intake passage 12 in this way, the opening 16 of the cylinder head side wall and the intake port 5 are connected in an oblique direction, and the passage cross-sectional area of the portion continuous to the intake port 5 is changed. The angle can be made gentle and the angle of inflow into the intake port 5 can be increased. Therefore, it is possible to improve the intake charge efficiency. Also, the intake passage
Since it is possible to form the ventilation passage 15 having a relatively large cross-sectional area in the lower portion of the portion 12, it is possible to improve the cooling performance.

FIG. 3 partially shows a mold 21 for manufacturing the cylinder head 1 described above. The mold 21 is composed of a mother die 22 for forming a side wall portion of the cylinder head 1 and a core 23 attached to the mother die 22 for forming the intake passage 12, and the core 23 is the above intake It has a spiral shape corresponding to the shape of the passage 12, and is engaged with the matrix 22 so as to be rotatable around the center line C of the spiral. When the die plate (not shown) is closed, the core 23 is prevented from rotating with the stopper pin 24, etc., and when the die plate is opened, the stop 23 can be freely rotated. Thus, when the mother die 22 is linearly moved along the center line C of the spiral, the core 23 is pulled out while rotating along the spiral axis.

FIG. 4 shows another embodiment of the mold 21. This core
23, a base portion 26 is fitted to a guide member 25 fixed to the die plate side, a spiral groove 27 is recessed in an outer peripheral surface of the base portion 26, and an inner periphery of a base portion receiving hole 28 in the guide member 25. A pin 29 projecting from is engaged with the spiral groove 27. According to this, when the guide member 25 is moved in the axial direction,
Since the core 23 is rotated, the core 23 can be pulled out as in the first embodiment.

[Effects of the Invention] As described above, according to the present invention, it is possible to form the three-dimensionally curved intake passage with the extraction core. Therefore, the intake passage having a curved shape that smoothly connects to the intake port can be formed by die-casting at a position avoiding interference with the head bolt hole and the push rod insertion hole, which simplifies the engine manufacturing process. Has a great effect on

[Brief description of drawings]

FIG. 1 shows a cylinder head according to the invention as shown in FIG.
FIG. 2 is a cross-sectional view cut along the line I, and FIG.
FIG. 2 is a sectional view taken along line II-II of FIG. 1. FIG. 3 is a partial sectional view of a mold for manufacturing a cylinder head according to the present invention, and FIG. 4 is a partial sectional view showing another embodiment of the mold. 1 ... Cylinder head, 2 ... Upper surface 3 ... Lower surface, 4 ... Combustion chamber 5 ... Intake port, 6 ... Exhaust port 7 ... Valve stem guide 8.9 ... Head bolt hole 10 ... Push rod Insertion hole 11 …… Plug mounting hole, 12 …… Intake passage 13 …… Exhaust passage, 14 …… Cooling fin 15 …… Ventilation passage, 16 …… Opening 21 …… Mold, 22 …… Mother mold 23 …… Medium Child 24: Stopper pin 25: Guide member 26: Fitting part 27: Spiral groove 28: Receiving hole 29: Pin

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display area F02F 1/24 B 7710-3G 1/42 F 7710-3G

Claims (2)

[Claims] 1. A cylinder head of an engine formed by die casting, wherein an intake passage extending from an opening on an outer surface of a Linda head to a vicinity of an intake port of a combustion chamber has a straight axis with a constant curvature. A cylinder head for an engine, which is in the shape of a spiral tube wound around a straight axis at a constant lead angle. 2. A cylinder head mold for forming a cylinder head of an engine, wherein a core for forming an intake passage extending from an opening on an outer surface of a Linda head to a vicinity of an intake port of a combustion chamber. For a cylinder head, which has a spiral shape wound around a linear axis with a constant curvature and a constant advance angle, and is rotatable about the central axis of the spiral and movable back and forth along the central axis. Mold.