JPH04224263A - Construction for cooling cylinder in multicylinder engine - Google Patents

Abstract

PURPOSE:To make a cylinder block compact and in light weight in a multicylinder engine in which cylinders are cooled by flowing cooling liquid through grooves in grooved cylinder liners. CONSTITUTION:Cylinder liners 1 are provided with cooling grooves comprising multiple annular grooves 2 and multiple axial grooves 3 around their outer peripheries. Then lands 5 between the annular grooves 2 for both liners are inserted into the grooves 2 for the liners 1 adjacent to each other, respectively, and made in contact with each other. Flat surfaces 6 of both liners 1 with which a part of the periphery of the uppermost land 5 formed flat is made in contact. Then a bore 8 is formed in a cylinder block 7 to insert these multiple cylinder liners 1, and these multiple cylinder liners 1 are inserted into the bore 8.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder cooling structure for a multi-cylinder engine, in which the cylinders are cooled by flowing a coolant through the grooves of a grooved cylinder liner.

0002

[Prior Art] Coolant grooves are formed on the outer peripheral surface of a liner, and this liner is fitted into the bore of a cylinder block to cool the space defined by the inner peripheral surface of the cylinder block bore and the groove. BACKGROUND ART A cooling structure for cylinders in a multi-cylinder engine is known, which has a liquid flow path and cools the cylinders by flowing a coolant at high speed through the coolant flow path.

0003

[Problems to be Solved by the Invention] In the above, the cylinder block is provided with a plurality of bore portions at intervals into which the cylinder liner is inserted, and the pitch between the bores is larger than the outside diameter of the liner. There is.

However, in recent years, there has been a demand for engines to be smaller and lighter, and the present invention meets these demands. That is, the present invention focuses on the pitch between bores (the pitch between liners)
It is an object of the present invention to provide a cooling structure for cylinders in a multi-cylinder engine in which the cylinder block can be made smaller and lighter than the outer diameter of the liner.

[0005]

[Means for Solving the Problems] The structure of the present invention is directed to a cylinder in a multi-cylinder engine, in which a coolant groove is formed on the outer circumferential surface of a liner, and the cylinder is cooled by flowing the coolant into the coolant groove. In this cooling structure, the land portions between the coolant grooves of adjacent liners are inserted into each other, and the land portions are arranged so as to be in contact with each other, and the land portions of the uppermost land portion are arranged so that the land portions are arranged so as to be in contact with each other, and The cylinder block has a bore portion into which the plurality of cylinder liners are inserted, and the cylinder block has a bore portion into which the plurality of cylinder liners are inserted. It is characterized by a liner inserted into it.

[0006]

[Function] The lands between the coolant grooves of adjacent liners are inserted into each other's coolant grooves, and the lands are placed in contact with each other, and a part of the uppermost land in the circumferential direction Since adjacent liners having flat surfaces are arranged with their flat surfaces in contact with each other, the pitch between the liners can be made smaller than the outer diameter of the liners. Therefore, the cylinder block can be made smaller and lighter.

[0007] Furthermore, the coolant flowing through the coolant grooves has a small cross-sectional area because the lands between the coolant grooves are inserted into the coolant grooves of adjacent liners. The flow velocity increases in that area. Therefore, since the heat transfer coefficient of the cooling fluid in that portion becomes large, the mutually adjacent portions of the cylinder liner are cooled more than other circumferential portions. Therefore, the portions of the cylinder block with poor heat dissipation efficiency in the circumferential direction of the liner are cooled more, contributing to uniformity of temperature in the circumferential direction of the liner.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A case in which an embodiment of the present invention is applied to an in-line four-cylinder engine will be described below with reference to the drawings.

In FIGS. 1 to 3, a cylinder liner 1 has a cooling oil groove formed on its outer periphery, and the cooling oil groove has a plurality of annular grooves 2 formed at equal intervals in the axial direction of the liner. , a plurality of axial grooves 3 that connect adjacent annular grooves 2 to each other, and an axial groove 4 for discharge connected to the annular groove 2 at the lowermost end.

Then, the land portions 5 between the annular grooves 2 are inserted into the annular grooves 2 of adjacent cylinder liners 1, and the land portions 5 are arranged so as to be in contact with each other, and the uppermost land portion 5 A partially flat surface 6 in the circumferential direction of
Adjacent liners 1 are arranged with their flat surfaces 6 in contact with each other. The cylinder liners 1 at both ends in FIG. 3 are provided with one flat surface 6 in the circumferential direction, and the two middle cylinder liners 1 are provided with two flat surfaces 6 in the circumferential direction.

[0011] The cylinder block 7 is formed with a bore portion 8 into which the plurality of cylinder liners 1 are fitted. The lowermost land portion 5 of the cylinder liner 1 is placed on a liner receiving portion 9 provided at the lower end so as to protrude inward.

[0012] Therefore, since the pitch between the cylinder liners 1 is smaller than the outer diameter of the liners 1, the size of the cylinder block 7 can be reduced, and the engine can be made smaller and lighter.

[0013] Then, in the cooling oil groove of the cylinder liner 1,
Engine lubricating oil flows from top to bottom at high speed to cool the cylinder, and the cooling oil is discharged from the axial groove 4 for discharge to an oil pan (not shown). In this case, the cooling oil flows sequentially from top to bottom in the annular groove 2 via the axial groove 3. At the portion where the land portions 5 between the grooves 2 enter into each other, the cross-sectional area of the cooling oil flow path becomes smaller (see FIGS. 1 and 2), so the flow velocity becomes higher.

[0014] Therefore, since the heat transfer coefficient of the cooling oil in that portion becomes large, the mutually adjacent portions of the cylinder liner 1 are cooled more than other circumferential portions. Therefore, in the circumferential direction of the liner 1, the portions of the cylinder block 7 with poor heat dissipation efficiency are further cooled, and the temperature in the circumferential direction of the liner 1 can be made uniform.

[0015] The coolant groove is not limited to the one shown above, but may also include, for example, a spiral groove, or the one shown in U.S. Pat. The plurality of annular grooves are divided into a plurality of annular groove groups. Two axial grooves are formed to communicate with each other and to form an outlet and an inlet of the coolant, and adjacent annular groove groups may be formed by connecting the outlet and inlet of the coolant in series.

[0016]

As explained above, according to the present invention, in a cylinder cooling structure for a multi-cylinder engine in which the cylinders are cooled by flowing a coolant into the grooves of a grooved cylinder liner, adjacent liners are The land portions between the coolant grooves are inserted into the coolant grooves, and the land portions are arranged so as to be in contact with each other, and a portion of the uppermost land portion in the circumferential direction forms a flat surface so that adjacent liners The cylinder block is arranged with its flat surfaces in contact with each other, and the cylinder block has a bore portion into which the plurality of cylinder liners are fitted, and the plurality of cylinder liners are fitted into the bore portion, so that the cylinder block can be made smaller and lighter, and the engine can be made smaller and lighter.

[0017] In addition, at the portion where the land portions between the coolant grooves of adjacent liners enter into each other, the cross-sectional area of the coolant flow path becomes smaller, so the flow velocity increases, and the cooling of that portion is reduced. Since the heat transfer coefficient of the liquid is increased, adjacent portions of the cylinder liner are cooled more than other circumferential portions. Therefore, in the circumferential direction of the liner, the portions of the cylinder block with poor heat dissipation efficiency are further cooled, which can contribute to uniformity of temperature in the circumferential direction of the liner.

[Brief explanation of the drawing]

FIG. 1 is a sectional view taken along line II in FIG. 3;

FIG. 2 is a cross-sectional view of the cylinder liner in FIG. 1;

FIG. 3 is a plan view of a cylinder block into which the cylinder liner of the present invention is fitted.

[Explanation of symbols]

1 Cylinder liner 2 Annular groove 3 Axial groove 4 Axial groove 5 Land part 6. Flat surface 7 Cylinder block 8 Bore part 9 Liner receiving part

Claims (1)

[Claims] Claim 1: In a cylinder cooling structure for a multi-cylinder engine, in which a cooling fluid groove is formed on the outer circumferential surface of the liner, and the cylinder is cooled by flowing the cooling fluid into the cooling fluid groove, adjacent liners are cooled from each other. The adjacent liners are arranged so that the lands between the cooling fluid grooves are inserted into the cooling fluid grooves and the lands are in contact with each other, and a part of the uppermost land in the circumferential direction forms a flat surface. are arranged with their flat surfaces in contact with each other, the cylinder block has a bore portion into which the plurality of cylinder liners are fitted, and the plurality of cylinder liners are fitted into the bore portion. Cylinder cooling structure in a multi-cylinder engine.