JPH0727014A - Water jacket structure of multicylinder engine - Google Patents

Abstract

PURPOSE:To efficiently cool the area between cylinder bores even if the pitch between cylinder bores is narrow by boring a bypass passage, which cross the area between the cylinder bores and both ends of which connect with a water jacket, in a cylinder block. CONSTITUTION:A plurality of cylinder bores xsi1-xsi4 are arranged in series in a cylinder block 3, and water jackets 11 and 12 inclusively surround two cylinder bores each xsi1 and xsi2, and xsi3 and xsi4. What is more, the water jackets 11 and 12 break between the cylinder bores xsi1 and xsi2, and xsi3 and xsi4. Bypass passages 15 and 16, which cross the area between cylinder bores xsi1 and xsi2, and xsi3 and xsi4 and both ends of which connect with the water jackets 11 and 12 are bored in a cylinder block 3. Accordingly, cooling water for the water jackets 11 and 12 circulate in the bypass passages 15 and 16 crossing between the cylinder bores xsi1 and xsi2, and xsi3 and xsi4, so the area between cylinder bores xsi1 and xsi2, and xsi3 and xsi4 can be cooled efficiently.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water jacket structure for a multi-cylinder engine.

[0002]

2. Description of the Related Art Recent multi-cylinder engines, especially in-line multi-cylinder engines, have a minimum cylinder bore pitch (interval between cylinder bores) in order to make them lightweight and compact. According to this, since the length of the crankshaft is shortened, there is also an effect of preventing the crankshaft from swinging at high output and high rotation.

FIG. 5 is a top view of a cylinder block of an in-line four-cylinder engine in which the cylinder bore pitch is thus narrowed. Four cylinder bores # 1 to # 4 are formed in the cylinder block 100, and the pitch between the cylinder bores # 1 and # 2 and the pitch between the cylinder bores # 3 and # 4 are minimized. There is. Incidentally, 102 is a cam chain chamber.

In this way, when the pitches between the cylinder bores # 1 and # 2 and between the cylinder bores # 3 and # 4 are minimized,
Due to space constraints, it is impossible to surround the cylinder bores # 1 to # 4 with a water jacket all around. Therefore, the water jacket 103 that comprehensively surrounds the circumferences of the cylinder bores # 1 and # 2 and the water jacket 104 that comprehensively surrounds the circumferences of the cylinder bores # 3 and # 4 are provided.

[0005]

However, in such a shape of the water jackets 103 and 104,
Between the cylinder bores # 1 and # 2, and between the cylinder bores # 3 and #
Since the water jackets 103 and 104 are interrupted between 4 and 4, the cylinder bores # 1, # 2 and # 3, respectively.
There is a risk that the space between # 4 is not cooled efficiently, the temperature of this portion becomes higher than that of other portions, and the cylinder bores # 1 to # 4 are distorted.

Further, the heat of the piston sliding in each of the cylinder bores # 1 to # 4 is less likely to be radiated to the cylinder block 100, so that the piston may be thermally deformed. When the cylinder bore and the piston are deformed in this way, oil and blow-by gas leak from between the cylinder bore and the piston, and in the worst case, the piston sticks to the cylinder bore (burns).

The present invention has been made in order to solve the above problems, and a water jacket structure of a multi-cylinder engine capable of efficiently cooling the space between the cylinder bores even if the pitch between the cylinder bores is narrowed. The purpose is to provide.

[0008]

To achieve the above object, in a water jacket structure for a multi-cylinder engine according to the present invention, a plurality of cylinder bores are arranged in series in a cylinder block, and the circumference of two or more cylinder bores is covered. In a water jacket structure of a multi-cylinder engine in which a water jacket that surrounds the cylinder bore is provided, and the water jacket is interrupted between a plurality of cylinder bores that are comprehensively surrounded by the water jacket, the water jacket is crossed between the cylinder bores and water The cylinder block has a bypass passage connected to the jacket.

Further, the bypass passage is formed in a substantially V shape extending from both sides of the cylinder bore row toward the bottom dead center side toward the center line side of the cylinder bore row.

Further, it is characterized in that the position of the lowermost portion of the bypass passage formed in a substantially V shape is matched with the upper surface position of the piston placed at the bottom dead center.

[0011]

According to the water jacket structure of the multi-cylinder engine having the above-described structure, even if the pitch between the cylinder bores is narrowed, the cooling water from the water jacket circulates in the bypass passage that crosses between the cylinder bores. The space is cooled efficiently.

Further, since the bypass passage is formed in a substantially V shape extending from both sides of the cylinder bore row toward the bottom dead center side toward the center line side of the cylinder bore row, it is drilled from the upper opening of the water jacket. The bypass passage can be easily processed and formed, and the entire length of the bypass passage is increased, so that the cooling efficiency is improved. Moreover, the bypass passage can be easily post-processed in the ready-made cylinder block.

Further, since the position of the lowermost part of the bypass passage formed in a substantially V shape is aligned with the position of the upper surface of the piston placed at the bottom dead center, the total length of the length with which the combustion gas contacts in the cylinder bore is set. Bypass passages are formed thereover, and cooling efficiency is improved.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a left side view of a multi-cylinder engine to which the present invention is applied. The engine 1 is, for example, an in-line four-cylinder engine for a motorcycle, in which a cylinder block 3 and a cylinder head 4 are sequentially installed above a front portion of a crankcase 2, and an intake port provided at a rear portion of the cylinder head 4 is provided. The carburetor 5 is connected, and an exhaust muffler 6 is connected to an exhaust port provided in the front part of the cylinder head 4.

FIG. 2 is a top view of a cylinder block 3 showing an embodiment of the water jacket structure according to the present invention, and FIG. 3 is a vertical sectional view taken along the line III-III of FIG.
In the cylinder block 3, four cylinder sleeves 7A to 7D made of iron are arranged in series on a main body made of aluminum alloy, and cylinder bores # 1 to # 4 are formed in the cylinder sleeves 7A to 7D, respectively. The lower ends of the cylinder sleeves 7A to 7D project from the lower surface of the cylinder block 3.

Around each of the cylinder bores # 1 to # 4, 1
Two stud bolt holes 8 are formed, and a stud bolt (not shown) rising from the crankcase 2 is inserted into the stud bolt hole 8 from below, whereby the cylinder block 3 and the cylinder head 4 are attached to the crankcase 2. Fixed. A cam chain chamber 9 is provided between the cylinder bores # 2 and # 3, and cooling fins 10 are formed around the cylinder block 3.

Water jackets 11 and 12 are provided around the cylinder bores # 1 to # 4, and the water jackets 11 and 12 are provided on the rear surface of the cylinder block 3.
The cooling water inlets 13 and 14 connected to are provided. A water pump (not shown) is installed in the crankcase 2, and cooling water discharged from the water pump is injected into the water jackets 11 and 12 from the cooling water inlets 13 and 14.

The cooling water injected into the water jackets 11 and 12 cools the cylinder bores # 1 to # 4 and also circulates in the water jacket in the cylinder head 4 to cool the periphery of the combustion chamber.

Now, this engine 1 has a cylinder bore #
Since the engine 1 is made lighter and more compact by narrowing the pitch between 1 to # 4 as much as possible, it is not possible to surround the entire circumference of each cylinder bore # 1 to # 4 with a water jacket due to space limitations. Therefore, the left water jacket 11 comprehensively surrounds the cylinder bores # 1 and # 2, and the right water jacket 12 comprehensively surrounds the cylinder bores # 3 and # 4. Therefore, between the cylinder bores # 1 and # 2 and between the cylinder bores # 3 and # 4, the water jacket 11,
12 is broken.

The cylinder block 3 has a cylinder bore #
Cross between 1 and # 2 and between cylinder bores # 3 and # 4,
Bypass passages 15 and 16 having both ends connected to the water jackets 11 and 12 are bored. As shown in FIG. 4, the bypass passages 15 and 16 are formed obliquely from the upper openings of the water jackets 11 and 12 by drilling or the like, and are located on both sides of the cylinder bores # 1 to # 4 on the center line C side of the same row. V extending toward bottom dead center toward
It is formed in a letter shape. And the bypass passages 15 and 1
The lowermost position of 6 is aligned with the upper surface position A of the piston (not shown) placed at the bottom dead center.

In the case of such a water jacket structure, even if the pitch between the cylinder bores # 1 to # 4 is narrowed, the bypass passages 15 and 16 crossing the cylinder bores # 1, # 2 and # 3, # 4 are provided. Since the cooling water from the water jackets 11 and 12 circulates, the cylinder bores # 1 and # 2 and the cylinder bores # 3 and # 4 are efficiently cooled.

Further, since the bypass passages 15 and 16 are formed in a substantially V-shape extending from the both sides of the row of cylinder bores # 1 to # 4 toward the center line C side of the row toward the bottom dead center side, the water jacket 11 is formed. The bypass passages 15 and 16 can be easily formed from the upper openings of the
Since the overall length of the bypass passages 15 and 16 is increased, the cooling efficiency is improved. Moreover, the bypass passages 15 and 16 can be easily post-processed in the ready-made cylinder block.

Further, since the lowermost position of the bypass passages 15 and 16 formed in a substantially V shape is aligned with the upper surface position A of the piston located at the bottom dead center, the cylinder bore # 1 is formed.
The bypass passages 15 and 16 are formed over the entire length of the length in contact with the combustion gas in # 4 to improve the cooling efficiency.

In this embodiment, the bypass passages 15 and 1 are
6 are formed one by one, but the bypass passages 15 and 1
By forming a plurality of 6, the cooling efficiency can be further enhanced. The present invention can be applied not only to the in-line multi-cylinder engine, but also to a multi-cylinder engine having a cylinder bore arrangement of V type, horizontally opposed type, square type, or the like.

[0025]

As described above, in the water jacket structure for a multi-cylinder engine according to the present invention, a plurality of cylinder bores are arranged in series in a cylinder block, and a water jacket that comprehensively surrounds the circumference of two or more cylinder bores. In a water jacket structure of a multi-cylinder engine in which a water jacket is interrupted between a plurality of cylinder bores that are comprehensively surrounded by the water jacket, a bypass that crosses between the cylinder bores and connects both ends to the water jacket. The passage is formed in the cylinder block.

Therefore, even if the pitch between the cylinder bores is narrowed, the cooling water from the water jacket circulates in the bypass passage that crosses between the cylinder bores, so that the space between the cylinder bores can be efficiently cooled.

Further, since the bypass passage is formed in a substantially V shape extending from the both sides of the cylinder bore row toward the bottom dead center side toward the center line side of the cylinder bore row, it is drilled from the upper opening of the water jacket. The bypass passage can be easily processed and formed, and the entire length of the bypass passage is increased, so that the cooling efficiency is improved. Moreover, the bypass passage can be easily post-processed in the ready-made cylinder block.

Further, since the lowermost position of the bypass passage formed in a substantially V shape is aligned with the upper surface position of the piston placed at the bottom dead center, the length of the contact length of the combustion gas in the cylinder bore is reduced. Bypass passages are formed over the entire length to improve cooling efficiency.

[Brief description of drawings]

FIG. 1 is a left side view of a multi-cylinder engine to which the present invention is applied.

FIG. 2 is a top view of the cylinder block taken along the line II-II of FIG. 1, showing an embodiment of the water jacket structure according to the present invention.

FIG. 3 is a vertical cross-sectional view of the cylinder block taken along the line III-III in FIG.

FIG. 4 is a vertical cross-sectional view of the cylinder block taken along line IV-IV in FIG.

FIG. 5 is a top view of a cylinder block of an in-line four-cylinder engine showing a conventional technique.

[Explanation of symbols]

 1 Engine 2 Crankcase 3 Cylinder Block 4 Cylinder Head 7A to 7D Cylinder Sleeve 11,12 Water Jacket 15,16 Bypass Passage # 1 to # 4 Cylinder Bore A Top Position of Piston at Bottom Dead Center C Centerline of Cylinder Bore Row

Claims (3)

[Claims] 1. A plurality of cylinder bores are arranged in series in a cylinder block, and a water jacket is provided to comprehensively surround the circumference of two or more cylinder bores, and the plurality of cylinder bores are comprehensively surrounded by the water jacket. In a water jacket structure of a multi-cylinder engine in which the water jacket is interrupted, the water jacket of the multi-cylinder engine is characterized in that a bypass passage that intersects between the cylinder bores and has both ends connected to the water jacket is bored in the cylinder block. Construction. 2. The multi-passage according to claim 1, wherein the bypass passage is formed in a substantially V shape extending from both sides of the cylinder bore row toward the bottom dead center side toward the center line side of the cylinder bore row. Water jacket structure of cylinder engine. 3. The multi-cylinder according to claim 2, wherein the position of the lowermost portion of the bypass passage formed in a substantially V shape is matched with the position of the upper surface of the piston placed at the bottom dead center. Engine water jacket structure.