JPS62103448A - Engine structure - Google Patents

Abstract

PURPOSE:To make a cylinder head common to various kinds of engines having three intake and exhaust valves in total, to reduce the manufacturing cost of engines, by arranging passages and holes which are formed in the cylinder head, corresponding to a cylinder block, in point-symmetry with respect to the center of the cylinder head. CONSTITUTION:At a lower section deck surface 1A of a cylinder head 1, three, in total, of ports P1 through P3 are opened within a combustion recess 2, one being on one side of the center line LC in the crank axial direction and two being on the other side of the center line LC, and a spark plug hole 3 is formed at a position which is substantially equidistant from the center of the ports. Further, holes and passages such as, cooling water passages W, tension bolt holes (t) and the like are all arranged point symmetry with respect to the center O of the cylinder head 1. With this arrangement, it is possible to cope with the case of two intake valves or the case of two exhaust valves, by reversing the mounting positions of intake and exhaust manifolds, and therefore, it is possible to use the cylinder head to various kinds of engines.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an engine structure having a total of three intake and exhaust valves per cylinder.

[Prior art] Engines in which two intake valves and one exhaust valve are provided for each cylinder are well known, and it is necessary to devise an equal drive system in which the opening and closing timings of these two intake valves are different. This provides the advantage that stratified combustion can be achieved.

Therefore, although an engine with one intake valve and two exhaust valves for each cylinder is not unthinkable in terms of combination, it was considered to be very impractical in reality.

However, in a supercharged engine that supplies intake air under pressure, the density of exhaust energy can be increased by shortening the opening period of the exhaust valve, which improves both torque performance and transient response in the low speed range. This improvement was experimentally verified by the inventors' experiments. In this way, even when the exhaust valve opening period is shortened in the low speed range, there is a demand for ensuring a sufficient valve opening period in the high speed range to ensure scavenging performance, and in that sense, the exhaust valve opening period is shortened in the high speed range. Preferably, the opening period of the valve is variable.

From this point of view, two exhaust valves with different opening periods are arranged on the exhaust side, and at low speeds, the exhaust valve set for a longer valve opening period is stopped, and the exhaust valve set for a shorter valve opening period is operated. method has the highest feasibility.

In this sense, the combination of one intake valve and two exhaust valves can be considered realistic. In that case, if you try to share a cylinder block with an engine with 2 intake valves and 1 exhaust valve, the cooling water passages and oil passages of the cylinder block, as well as various bolt holes, etc., will be located in asymmetric positions. Because some cylinder heads are installed, the cylinder head cannot be shared, and a separate dedicated mold is used to create one intake valve.

It is necessary to manufacture a cylinder head exclusively for two exhaust valves.

[Object of the Invention] The object of the present invention is to use a common cylinder head without having to change the design, whether it is a combination of two intake valves and one exhaust valve, or a combination of one intake valve and two exhaust valves. The objective is to provide an engine structure that can

[Configuration of the Invention] Therefore, the present invention has been designed to correspond to the cylinder block.
The basic feature is that all the passages and holes are arranged in pairs in a positional relationship that is symmetrical with respect to the center of the cylinder head.

[Effects of the Invention] According to the present invention, it is possible to use a common cylinder head for three intake and exhaust valves, and the head manufacturing cost can be halved.

[Example] Hereinafter, an example of the present invention will be specifically described with reference to the accompanying drawings.

As shown in the lower deck surface IA of the cylinder head 1 in FIG. 3 ports P+, 1 on the other side, 2 on the other side,
P2. P 3 is opened and these three ports P
I, P 2. Plug holes 3 for spark plugs are provided at positions approximately equidistant from each center of P 3 .

Now, when we consider the intersection O between the crankshaft direction center line LC and the width direction center line TC orthogonal thereto as the center of the cylinder head ■, all the holes and passages are point symmetrical with respect to the center O of the cylinder head 1. They are arranged in a pairwise positional relationship.

More specifically, the cooling water passage W is shown in white, the bolt holes t are shown in hatching diagonally to the right, the dowel pin holes are shown in cross hatching, and the oil passage 0 is shown in hatching diagonally to the left. In addition, all of these passages and holes are arranged point-symmetrically.

Of the passages and holes arranged point-symmetrically as above, those that are not actually used may be closed off with blind plugs, but the corresponding passages and holes on the cylinder block side may be closed on the cylinder head i side. It is sufficient if they are formed point-symmetrically so that they correspond to each other.

Moreover, as shown in FIG. 2, each port P+, P.

4. A fitting hole into which the valve stem of a valve (not shown) that opens and closes is fitted.
5 is formed to have a symmetrical axis with respect to the vertical center line VC of the cylinder head l.

Each port P1 in the cylinder head 1. In the side wall opening of P2, in other words, in the connection part with the manifold (not shown), reliefs 6 and 7 are respectively formed to receive the tip of the fuel injection nozzle (not shown). (Fig. 3, 4
(see figure).

Also, two ports P2. P3 is divided into two parts within the cylinder head l, and is configured to merge into one exhaust passage 10 in front of the side wall part IS.

Further, as shown by the hatching downward to the right in FIGS. 3 and 4, each side wall IS of the cylinder head 1 has holes 8 and 8 for circulating cooling water to the intake manifold (not shown). , 9.9 are provided respectively.

With this configuration, whether the intake side has two valves or the exhaust side has two valves, it can be easily handled by reversing the installation of the intake manifold and exhaust manifold. There is no need to provide a head.

[Brief explanation of drawings]

1 is a bottom view of a cylinder head according to an embodiment of the present invention, FIG. 2 is a sectional view taken along line 2-2 in FIG. 1, and FIGS. 3 and 4 are a direction A and a direction B in FIG. It is a directional view. 1... Cylinder head, Pl, P2. P3・
... Port, W... Cooling water passage, T - Tension bolt, K - Dowel pin hole, 0... Oil passage. Patent applicant: Mazda Motor Corporation Representative: Patent attorney: Mr. Hao et al. (cited above) and 2 others C)

Claims (1)

[Claims] (1) In an engine equipped with a total of three intake and exhaust valves per cylinder, the passages and holes on the cylinder head side corresponding to the cylinder block side are arranged in a pair of positional relationships that are symmetrical with respect to the center point of the cylinder head. An engine structure characterized by being arranged in.