JPH02119611A - Cooling device for four-cycle engine - Google Patents

Abstract

PURPOSE:To simplify construction by forming spark plug holes on a cylinder, fitted by a specified angle toward the exhaust side, and installing a guide passage on an upper part of the exhaust port in a cylinder head, which guides cooling water to the outside of an engine. CONSTITUTION:On a cylinder 4, an ignition plug installation hole 18 is formed, tilted by a specified angle, for example, by about 15 deg. toward the exhaust side as against the perpendicular L1 of the cylinder head 4. A cooling water passage 20 surrounding each cylinder is formed in the cylinder head 4. Furthermore, on an upper part of the exhaust port 14 of the cylinder head 4, a guide passage 22 is formed, which guides the cooling water from the cooling water passage 20 to the outside of an engine 2. That is, cooling water passages 20-1 to 20-4 of each cylinder are communicated with the guide passage 22, and the downstream side of the guide passage 22 is communicated with the cooling water exit passage 24 of the cylinder head 4. This arrangement makes the construction of the guide passage 22 simpler and its cost less.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a cooling device for a four-stroke engine, and in particular, a cylinder head is formed with a spark plug hole inclined toward the exhaust side, and the spark plug hole This invention relates to a cooling device for a four-stroke engine that cools the surroundings.

[Prior Art] A cooling system for a four-stroke engine has a cooling water passage provided in a cylinder head and a cylinder block, and coolant is forced into the cooling water passage to cool the engine.

Further, as a cooling device for the four-stroke engine, there is one disclosed in Japanese Utility Model Application Publication No. 82-52220.

In the engine cooling system disclosed in this publication,
A spark plug hole is formed vertically in the cylinder head, and an opening is formed on the exhaust side of the cylinder head by a lateral extension, and this opening is connected to the water pump on the upstream side through a cooling water supply piping. The system aims to improve engine cooling efficiency by ensuring a reliable supply of cooling water to the engine.

[Problems to be Solved by the Invention] Incidentally, in the conventional cooling device for a four-stroke engine, as shown in FIG. For example, in the inclined spark plug hole 118, which may be provided at an angle of about 15 degrees, the cross-sectional area of the cooling water passage 120 around the spark plug 116 on the exhaust side is reduced by the exhaust port 114. be.

That is, as shown in FIG. 6, the gaps W1 and W2 at two locations between the mounting hole 118 of the spark plug 116 and the exhaust port 114 are approximately 3 mm.

For this reason, during casting of the cylinder head, it becomes difficult to hold the core for forming the cooling water passage, resulting in problems such as poor molding of the cooling water passage.

Furthermore, even if the cylinder head can be cast, the flow of the cooling water is hindered due to the narrow cross-sectional area of the cooling water passage in the gaps W1 and W2 between the hole 118 and the exhaust port 114. This has disadvantages in that the circulation of cooling water deteriorates and the cooling performance is significantly reduced, which is disadvantageous in practice.

[Objective of the Invention] Therefore, in order to eliminate the above-mentioned disadvantages, an object of the present invention is to provide a spark plug hole in the cylinder head of a four-stroke engine with a predetermined angle slanted toward the tJr air side, so that the exhaust gas inside the cylinder head is By integrally providing a guide passage for guiding the cooling water to the outside of the engine in the upper part of the port, the configuration of the guide passage is simple and the cost can be reduced, and the number of assembly steps can be reduced. Moreover, the present invention aims to realize a cooling device for a four-stroke engine that can reliably hold the core during casting.

[Means for Solving the Problems] To achieve this object, the present invention provides a cooling system for a four-stroke engine in which cooling water flows through the cylinder head to cool the engine. The engine is characterized in that the hole is inclined toward the exhaust side by a predetermined angle, and a guide passage for guiding the cooling water to the outside of the engine is integrally provided in the upper part of the exhaust port in the cylinder head.

[Operation] With the above-described configuration, the spark plug hole is provided in the cylinder head so as to be inclined toward the exhaust side by a predetermined angle, and a guide is provided in the upper part of the exhaust port in the cylinder head to guide the cooling water to the outside of the engine. When the passage is provided integrally, the structure of the guide passage is simplified, the cost is reduced, the number of assembly steps is reduced, and the core is reliably held during casting.

[Embodiments] Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

1 to 4 show embodiments of this invention. 1st
In Figures 1 to 4, 2 is a four-cycle engine, 4 is a cylinder head, 6 is an intake port, 8 is an intake valve, 10 is a combustion chamber, 12 is an exhaust valve, and 14 is an exhaust port.

As shown in Fig. 1.3, the cylinder spatula)'4 has
Inclined by a predetermined angle, for example, perpendicular L1 of the cylinder head 4
A mounting hole 18 for the spark plug 16 is formed at an angle of about 15 degrees toward the exhaust side.

Furthermore, as shown in FIG. 1, cooling water passages 20 are formed in the cylinder head 4 to respectively surround each cylinder (not shown).

A guide passage 22 for guiding the cooling water from the cooling water passage 2o to the outside of the four-stroke engine 2 is integrally provided in the upper part of the exhaust port 14 in the cylinder head 4.

To be more specific, as shown in FIG. 2, the cooling water passage 2 of each cylinder
0-1.20-2.2o-3, 2o-4 guide passage 22
The downstream side of the guide passage 22 is connected to the cooling water outlet passage 24 of the cylinder head 4.

Note that the reference numeral 26 is a thermostat (T/S) provided in the middle of the cooling water outlet passage 24.

Next, the effect will be explained.

The cooling water pumped to the four-stroke engine 2 by a water pump (not shown) cools each cylinder of the four-stroke engine 2, and then flows through each cooling water passage 20-1.20-2.20- in the cylinder head 4. 3. Pass through 20-4 and reach the guide passage 22.

The cooling water is guided to a cooling water outlet passage 24 by this guide passage 22, and is fed to a predetermined part such as a radiator through a thermostat 26.

By integrally molding the guide passage 22 into the cylinder head 4, the structure of the guide passage 22 can be simplified, the cost can be reduced, and this is economically advantageous. The exhaust side of the cylinder head 4 can be downsized, and since the guide passage 22 is not formed separately, the number of man-hours required for assembling the guide passage 22 can be reduced, which is advantageous in practice.

Also, the guide passage 22 allows the 4-cycle engine 2
The cooling efficiency can be improved by efficiently circulating the cooling water in the cylinder head 4.

Furthermore, when casting the cylinder head 4, the guide passage 2 is
2 can reliably hold the core, thereby improving the workability of casting work and reliably avoiding problems such as poor molding of the cooling water passage 20.

Furthermore, since there is no need to seal the mating surfaces of the cylinder head 4 and the guide passage 22 during maintenance, there is no risk of leakage, and usability can be improved.

[Effects of the Invention] As explained in detail above, according to the present invention, the spark plug hole is provided in the cylinder head of a four-cycle engine so as to be inclined toward the exhaust side by a predetermined angle, and the upper part of the exhaust port in the cylinder head is Since the guide passage for guiding the cooling water to the outside of the engine is integrally provided in the part, the configuration of the guide passage is simplified and the cost can be reduced, which is economically advantageous and is suitable for 4-stroke engines. The exhaust side can be made smaller, and the number of assembly steps can be reduced, which is advantageous in practice. Furthermore, cooling efficiency can be improved because the cooling water is efficiently circulated through the guide passage. Furthermore, when casting the cylinder head,
The core can be held securely by the guide passage, and the workability of the casting operation can be improved. Furthermore, there is no need for a seal at the mating surface between the cylinder head and the guide passage.
There is no risk of leakage, and usability can be improved.

[Brief explanation of drawings]

1 to 4 show a first embodiment of the present invention, FIG. 1 is a schematic enlarged sectional view of only the cylinder head, FIG. 2 is a schematic enlarged sectional view of a 4-cycle engine, and FIG. 3 is a schematic enlarged sectional view of the cylinder head. FIG. 4 is a schematic enlarged cross-sectional view showing the installation state of the mounting hole of the spark plug, and FIG. 4 is a schematic enlarged cross-sectional view showing the intake and exhaust ports of the cylinder head. Fig. 5.6 shows the prior art of the present invention, Fig. 5 is a schematic enlarged sectional view of the cylinder head, and Fig. 6 is a VI--
FIG. 3 is a schematic cross-sectional view taken along the VI line. In the figure, 2 is a 4-cycle engine, 4 is a cylinder head, 6 is an intake port, 8 is an intake valve, 10 is a combustion chamber, 12 is an exhaust valve, 14
is an exhaust port, 16 is a spark plug, 18 is a hole, 20 is a cooling water passage, 22 is a guide passage, 24 is a cooling water outlet passage,
26 is a thermostat (T/S). Patent Applicant Suzuki Motor Co., Ltd. Representative Patent Attorney Yoshimi Nishigo Figure 1 Figure 5 Figure 6 'W2

Claims (1)

[Claims] 1. In a cooling system for a four-cycle engine in which cooling water flows through the cylinder head to cool the engine, a spark plug hole is provided in the cylinder head at a predetermined angle toward the exhaust side, and the exhaust gas inside the cylinder head is cooled. A cooling device for a four-cycle engine, characterized in that a guide passage for guiding the cooling water to the outside of the engine is integrally provided in an upper portion of the port.