JP2010127081A - Internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internal combustion engine having an excellent fuel consuming efficiency, capable of eliminating the component force inward in the radial direction of a cylinder liner even if the cylinder liner is fastened to a cylinder head using a screw means, maintaining the roundness of the cylinder liner, and precluding friction between a piston and the cylinder liner. <P>SOLUTION: The internal combustion engine 100 is structured so that the cylinder liner 101 (2) installed on a cylinder block (1) is fastened to the cylinder head 200 (3) using the screw means 300 (4), wherein the screw means 4 is formed in square thread type. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an internal combustion engine in which a cylinder liner is fastened to a cylinder head by screw means.

  The cylinder block of the internal combustion engine is formed with a cylinder that accommodates the piston in a reciprocating manner.

  A cylindrical cylinder liner made of a material having excellent wear resistance is fastened to the cylinder head by screw means in the bore portion (cylinder bore) of the cylinder so as to withstand friction between the inner wall and the piston. .

  Specifically, the screw means has a male screw engraved on the upper outer periphery of the cylinder liner, and by screwing the male screw on a female screw engraved on the inner peripheral portion of the cylinder head, The cylinder liner is fastened to the cylinder head. (For example, refer to Patent Document 1).

  As the structure of the cylinder liner, two types of structures, a dry liner and a wet liner, are known.

Further, the female screw and the male screw, which are the screw means, are constituted by a triangular screw or a sawtooth screw that is a combination of a square screw and a triangular screw.
JP 10-47055 A JP 2002-276458 A

  Here, FIG. 4 is an enlarged cross-sectional view schematically showing a main part of a conventional internal combustion engine.

  In FIG. 4, the case where the screw means 300 is a triangular screw will be described as an example, but the same applies to the sawtooth screw.

  That is, in the internal combustion engine 100, a force P is applied in the axial direction of the cylinder liner 101 when the cylinder liner 101 is fastened to the cylinder head 200 by the screw means 300 or when the internal combustion engine 100 is operated.

  However, if this axial force P (hereinafter referred to as “axial force P”) is to be generated, the triangular screw which is the screw means 300 is inclined to the triangular screw in proportion to the axial force P. A component Pa is generated from the portion 301 in the inner diameter direction of the cylinder liner 101.

  For this reason, the component force Pa in the inner diameter direction of the cylinder liner 101 acts in the direction of reducing the inner diameter of the cylinder liner 101, and the roundness of the cylinder liner 101 is reduced.

  Specifically, the circular cylinder liner 101 is generally often deformed into an ellipse when its roundness decreases.

  Further, when the roundness of the cylinder liner 101 is lowered, the oil consumption is likely to increase.

  Further, when the oil consumption increases, the ring tension of a piston (not shown) that reciprocates in contact with the inner peripheral surface of the cylinder liner 101 must be increased. As a result, the piston and the cylinder liner 101 Friction increases.

  For this reason, the increase in the friction causes a problem that the ratio of the power extracted from the energy generated by the combustion of the internal combustion engine 100 is reduced, which leads to a reduction in combustion efficiency.

  An object of the present invention is to solve this problem, and to eliminate the component force in the inner diameter direction of the cylinder liner, to maintain the roundness of the cylinder liner and to prevent the friction between the piston and the cylinder liner. An excellent internal combustion engine is provided.

  In order to solve the above problems, an internal combustion engine according to the present invention is characterized in that a cylinder liner is fastened to a cylinder head by screw means, and the screw means is a square screw.

  Here, the square screw means a screw in which a thread of a male screw and a screw groove of a female screw are formed in a rectangular cross section including a square.

  Therefore, an axial force P is generated only in the axial direction of the square screw on the fastening surface of the screw thread and screw groove in the square screw, and the component force in the inner diameter direction of the cylinder head can be eliminated.

  The internal combustion engine of the present invention is characterized in that an inclined portion narrowed outward is formed on a surface facing the fastening surface of the square screw.

  Here, the fastening surface means a surface on which the axial force acts when the male screw and the female screw are tightened, and the facing surface means a surface on which the axial force does not act.

  In the present invention, an inclined portion narrowed outward is formed on a surface facing the fastening surface of the square screw, so that the processing of the square screw is performed while maintaining the axial force P generated on the fastening surface. In addition to improving the performance, it is possible to easily tighten the square screw.

  According to the internal combustion engine of the present invention, even if the cylinder liner is fastened to the cylinder head by screw means, the component force in the inner diameter direction of the cylinder liner can be eliminated.

  Therefore, the roundness of the cylinder liner can be maintained, the friction between the piston and the cylinder liner can be prevented, and the fuel efficiency of the internal combustion engine can be improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a partial cross-sectional view schematically showing an embodiment of the present invention, and FIG. 2 is an enlarged cross-sectional view showing a main part of FIG.

  The internal combustion engine A of the present embodiment is characterized in that a cylinder liner 2 assembled to a cylinder block (crankcase) 1 and a cylinder head 3 are fastened by screw means 4, and the screw means 4 is a square screw. There is. The details will be described below.

  The cylinder block 1 is integrally or dividedly cast with a light aluminum alloy or the like, as in the prior art.

  The cylinder liner 2 is formed into a cylindrical shape made of aluminum alloy or the like, and a male screw 41 constituting the screw means 4 is formed in the circumferential direction at a suitable position on the outer periphery of the cylinder liner 2.

  The cylinder liner 2 can be formed integrally with or separately from the cylinder block 1, but when the cylinder block 1 is an aluminum alloy casting or spheroidal graphite cast iron, in order to improve the wear resistance of the inner surface of the cylinder liner 2, It is desirable to form the cylinder liner 2 separately.

  A piston 5 is slidably fitted in the cylinder liner 2, and the piston 5 is connected to a crankshaft 7 via a connecting rod 6.

  A ring gasket 21 is placed on the upper end of the cylinder liner 2, and the cylinder head 3 is connected via the ring gasket 21.

  The cylinder head 3 is integrally formed of a lightweight aluminum alloy or the like, and a plurality of cylindrical receiving portions 31 are formed on the lower surface of the cylinder head 3 at positions corresponding to the cylinder liner 2.

  Further, on the inner peripheral surface of the receiving portion 31, a female screw 42 constituting the screw means 4 capable of screwing the male screw 41 of the cylinder liner 2 is formed in the circumferential direction.

  Further, the cylinder head 3 is provided with a cooling water passage 32 for circulating cooling water from a water pump (not shown).

  Specifically, the cooling water is circulated through the cooling water passage 32 from the first cylinder side of the cylinder liners 2 arranged in parallel to cool the cylinder liner 2.

  In the present embodiment, a wet liner structure in which the cylinder liner 2 is directly cooled by the cooling water is illustrated. However, the present invention is not limited to this, and the cylinder liner 2 is indirectly indirectly cooled by the cooling water. A dry liner structure that cools the substrate may be used.

  The cylinder block 1 and the cylinder head 3 are fixed to the outside of the cylinder liner 2 by rod-like head bolts 8 so as to be installed.

  The internal combustion engine A of the present embodiment configured as described above is assembled, for example, in the following manner.

  First, the upper end side of the cylinder liner 2 is inserted toward the receiving portion 31 of the cylinder head 3 and the cylinder liner 2 is rotated so that the male screw 41 of the cylinder liner 2 is temporarily attached to the female screw 42 of the cylinder head 3. Tighten.

  Next, the cylinder liner 2 is fastened with a predetermined torque, and the cylinder liner 2 is fastened to the cylinder head 3.

  At this time, an axial force P is generated in the upward direction in proportion to the torque on the fastening surface 43 of the screw means 4, that is, the lower surface of the male screw 41 and the lower surface of the female screw 42 in FIG.

  However, since the screw means 4 of the present embodiment is a square screw, all of this axial force P is generated only in the axial direction (upward direction) of the cylinder liner 2. There is no component force.

  Therefore, when the cylinder liner 2 is fastened to the cylinder head 3, the roundness of the cylinder liner 2 can be maintained without acting in the direction of reducing the inner diameter of the cylinder liner 2 due to the fastening.

  Moreover, since the roundness of the cylinder liner 2 can be maintained, oil consumption can be suppressed.

  Further, since the oil consumption is suppressed, the ring tension of the piston 5 that reciprocates in contact with the inner peripheral surface of the cylinder liner 2 can be maintained, and the increase in friction between the piston 5 and the cylinder liner 2 can be prevented. .

  Therefore, the ratio taken out as motive power from the energy generated by the combustion of the internal combustion engine A is good, that is, the fuel efficiency can be improved.

  Then, the lower end side of the cylinder liner 2 fastened to the cylinder head 3 is press-fitted into the cylinder block 1 and assembled.

  Thus, according to the internal combustion engine A of the present embodiment, even if the cylinder liner 2 is fastened to the cylinder head 3 by the screw means 4, the component force in the inner diameter direction of the cylinder liner 2 can be eliminated.

  Therefore, the roundness of the cylinder liner 2 can be maintained, the friction between the piston 5 and the cylinder liner 2 can be prevented, and the fuel efficiency of the internal combustion engine A can be improved.

  FIG. 3 is an enlarged cross-sectional view of a main part schematically showing another embodiment of the present invention.

  The parts common to FIGS. 1 and 2 are denoted by the same reference numerals, and redundant description is omitted. Only the features of the present embodiment will be described below.

  The internal combustion engine A of the present embodiment is characterized in that inclined portions 41a and 42a narrowed outward are formed on a surface facing the fastening surface 43 of the square screw.

  Specifically, an inclined portion 41a narrowed outward is formed on the surface of the male screw 41 that faces the fastening surface 43, and the female screw 42 corresponds to the inclined portion 41a of the male screw 41. An inclined portion 42a is formed on the surface to be formed.

  Therefore, according to the internal combustion engine A of the present embodiment, the inclined surfaces 41a and 42a narrowed outward are formed on the surface facing the fastening surface 43 of the square screw, thereby generating the fastening surface 43. While maintaining the axial force P, the workability of the square screw can be improved, and the tightening operation of the square screw can be facilitated.

It is the fragmentary sectional view showing one embodiment of the present invention. It is an expanded sectional view which outlined the principal part of FIG. It is an expanded sectional view of the important section showing other embodiments of the present invention. It is an expanded sectional view which outlined the principal part of the conventional internal combustion engine.

Explanation of symbols

A Internal combustion engine P Axial force Pa Component force 1 Cylinder block 2 Cylinder liner 3 Cylinder head 4 Screw means 41a, 42a Inclined portion 43 Fastening surface

Claims (2)

  An internal combustion engine in which a cylinder liner assembled to a cylinder block is fastened to a cylinder head by screw means, wherein the screw means is a square screw. The internal combustion engine according to claim 1,
An internal combustion engine characterized in that an inclined portion narrowed outward is formed on a surface facing a fastening surface of a square screw.

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