JP2004162539A - Fixing structure of cylinder liner to cylinder block - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing structure of a cylinder liner to a cylinder block for attaining at least any one of reducing the area of a press-in work part, restraining deformation of a bore and improving durability of a seal. <P>SOLUTION: (1) The cylinder liner 2 is formed separately from the cylinder block 1. The press-in work part 3 is arranged in a lower end part position of the cylinder liner 2. Radial directional clearance 5 is arranged between the cylinder liner 2 and the cylinder block 1 above the press-in work part 3 and under an overhang part 6. (2) The press-in work part 3 may be formed as a screw work part 3A. (3) A support part by a step part 7 of the overhang part 6 is sealed by a sealant 8. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a structure for fixing an internal combustion engine to a cylinder block of a cylinder liner.
[0002]
[Prior art]
Japanese Utility Model Laid-Open No. 59-64446 discloses a separate wet iron cylinder liner made of cast iron, which is provided over the entire length below the overhanging portion in the height direction of the liner, and is fitted to an aluminum alloy cylinder block. Also disclosed is a structure for fixing a cylinder liner to a cylinder block, in which an O-ring is provided at a fitting portion to prevent water leakage from a water jacket.
[0003]
[Patent Document 1]
JP-A-59-64446 [0004]
[Problems to be solved by the invention]
However, the conventional structure for fixing the cylinder liner to the cylinder block and the sealing structure have the following problems.
(1) Since the entire length below the overhanging part in the height direction of the liner is the press-fitting part or the fitting part with no gap, the processing area on the liner side and block side is wider than the area required for liner positioning. , The cost is great.
{Circle around (2)} The press-fitted part or the fitting part with no gap is thermally deformed during operation, and as a result,
-Deformation of the bore, resulting in deterioration of the roundness of the bore, enlargement of the bore, and
-There is a possibility that a fitting clearance is generated between the liner and the block, and the water sealing property is deteriorated.
{Circle around (3)} Since the seal using the O-ring is a portion where the temperature rises during engine operation, it is not desirable in terms of durability.
An object of the present invention is to provide a structure for fixing a cylinder liner to a cylinder block, which can significantly reduce the area of a press-fit processing portion.
Another object of the present invention is to provide a structure for fixing a cylinder liner to a cylinder block, which can suppress bore deformation due to thermal deformation of a press-fit processing portion.
Another object of the present invention is to provide a structure for fixing a cylinder liner to a cylinder block, with improved seal durability.
[0005]
[Means for Solving the Problems]
The present invention that achieves the above object is as follows.
(1) The cylinder liner is separate from the cylinder block,
A press-fit processing portion is provided at a lower end position of the cylinder liner, and positioning of the cylinder liner with respect to the cylinder block is performed only by the press-fit processing portion,
Above the press-fit portion, and below a water jacket around the upper part of the cylinder liner, a radial clearance is provided between the cylinder liner and the cylinder block.
Fixing structure of cylinder liner to cylinder block.
(2) The cylinder liner is separate from the cylinder block,
A screw portion is provided at a lower end position of the cylinder liner, and positioning of the cylinder liner with respect to the cylinder block is performed only by the screw portion,
Above the screw portion, and below a water jacket around the top of the cylinder liner, a radial clearance is provided between the cylinder liner and the cylinder block.
Fixing structure of cylinder liner to cylinder block.
(3) A protrusion corresponding to the bottom of the water jacket is provided on the cylinder liner and a step is provided on the cylinder block, and a seal is provided at a position where the protrusion is supported by the step. The structure for fixing a cylinder liner to a cylinder block according to (1) or (2), wherein the bottom of the water jacket is sealed with an agent.
[0006]
In the above (1) structure for fixing the cylinder liner to the cylinder block, the press-fit portion at the lower end of the liner is located below the water jacket around the upper portion of the cylinder liner, and the clearance is below the water jacket above the press-fit portion. The area of the press-in processing portion can be greatly reduced on both the liner side and the block side as compared with the case where the entire lower portion of the conventional water jacket is the fitting processing portion. In addition, since the clearance portion is provided, most of the clearance between the cylinder block and the cylinder liner has a clearance, so that bore deformation (enlargement and deterioration of roundness) during operation (at high temperature) can be suppressed.
The structure for fixing the cylinder liner to the cylinder block in the above (2) is such that the press-fitted portion in the above (1) is a threaded portion. Similarly to the above (1), both the liner side and the block side are screwed. The area of the processed part can be greatly reduced. In addition, since the clearance portion is provided, most of the clearance between the cylinder block and the cylinder liner has a clearance, so that bore deformation (enlargement and deterioration of roundness) during operation (at high temperature) can be suppressed.
In the structure (3) for fixing the cylinder liner to the cylinder block, since the bottom portion of the water jacket is sealed with a sealant at a portion supported by the step of the overhanging portion, a rubber O-ring is not used for the seal, and the sealant is not used. For example, by using a thermosetting resin, the durability of the seal can be improved.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a fixing structure of a cylinder liner to a cylinder block according to a preferred embodiment of the present invention will be described with reference to FIGS.
1 to 4 show a first embodiment of the present invention, and FIG. 5 shows a second embodiment of the present invention. Portions common to both embodiments are denoted by the same reference numerals in both embodiments.
[0008]
First, a first embodiment of the present invention will be described with reference to FIGS.
The structure for fixing a cylinder liner to a cylinder block according to the present invention includes a cylinder block 1 and a cylinder liner 2.
The cylinder block 1 is a cylinder block of a multi-cylinder internal combustion engine, and is made of an aluminum alloy or iron.
The cylinder liner 2 is a single wet liner. Here, "single" means that the cylinder liners are not continuous and each cylinder liner is independent. The term "wet" means that at least a part of the outer surface of the cylinder liner 2 comes into direct contact with the engine cooling water. The cylinder liner 2 is made of iron or an aluminum alloy.
In the illustrated example, the cylinder liner 2 is cast iron, and the cylinder block 1 is an aluminum alloy.
[0009]
In the structure for fixing the cylinder liner to the cylinder block according to the present invention, the cylinder liner 2 is of a separate type. Here, the “separate type” refers to a fixing system in which the cylinder liner 2 and the cylinder block 1 are separately manufactured, and the cylinder liner 2 is fixed to the cylinder block 1 by press-fitting or screwing. Therefore, it is different from the integral type by cast-in.
[0010]
At a position corresponding to the lower end portion of the cylinder liner 2, a press-fitting portion 3 by machining is provided on the outer peripheral surface 21 of the lower end portion of the cylinder liner 2 and the corresponding inner peripheral surface 11 of the cylinder block 1. The outer peripheral surface 21 of the lower end of the liner 2 and the inner peripheral surface 11 of the cylinder block 1 are press-fitted to each other. The positioning of the cylinder liner 2 with respect to the cylinder block 1 is performed only by the press-fit processing portion 3. Since the press-fit portion 3 is machined, the positioning accuracy is high.
[0011]
The vertical width of the press-fit portion 3, that is, the press-fit width h is 10% or less, preferably 8% or less of the overall length H of the cylinder liner 2. The reason for 10% and 8% is that exceeding these values makes it difficult to obtain the advantage of reducing the processing cost and the advantage of suppressing deformation of the cylinder bore. When the width of the press-fitted portion 3 is 10% or less of the total length H of the cylinder liner 2, the width is usually lower than the stroke region of the piston top ring, and is a thermally stable region.
[0012]
A radial clearance 5 is provided between the cylinder liner 2 and the cylinder block 1 above the press-fit processing portion 3 and below the water jacket 4 around the upper portion of the cylinder liner 2 (below the overhang portion 6 described later). ing. The outer peripheral surface 22 of the cylinder liner 2 facing the clearance 5 and the inner peripheral surface 12 of the cylinder block 1 may be cast surfaces that have not been machined. The water of the water jacket 4 does not come to the site of the clearance 5.
The size of the clearance 5 is such that the outer peripheral surface 22 of the cylinder liner 2 and the inner peripheral surface 12 of the cylinder block 1 do not interfere with each other even if there is a manufacturing tolerance, for example, 0 mm or more and 2 mm or less.
[0013]
At a position of the cylinder liner 2 corresponding to the bottom of the water jacket 4, a projecting portion 6 projecting radially into the water jacket 4 is formed, and a portion of the cylinder block 1 corresponding to the cylinder liner projecting portion 6. Is formed with a step 7 for supporting the cylinder liner overhang 6 from below.
[0014]
The overhang portion 6 is located near the center position (the 1 / 2H position) of the entire length H of the cylinder liner 2. The upper end of the clearance 5 extends to the lower surface of the overhang portion 6. When the length of the lower portion of the cylinder liner 2 below the lower surface of the overhang portion 6 is 0.5H and the width of the press-fit portion 3 in the vertical direction is 0.1H, the liner length of the portion where the clearance 5 is provided is 0.1H. 5H-0.1H = 0.4H. In the conventional structure, the clearance is 0 over the entire length (0.5H) of the length below the lower surface of the overhang of the cylinder liner. In the present invention, the clearance 5 is provided over 0.4H of the clearance.
[0015]
The bottom of the water jacket is sealed by a sealant 8 at a portion of the overhang portion 6 supported by the step portion 7. Before the cylinder liner 2 is mounted on the cylinder block 1, the sealant 8 is applied to the step portion 7 or the overhang portion 6, or the step portion 7 and the overhang portion 6 ((A) in FIG. 3). The sealant 8 is mainly composed of, for example, a thermosetting resin, and is, for example, an epoxy-based sealant resin, which is liquid when applied and solid after drying. When the cylinder liner 2 is press-fitted into the cylinder block 1, the lower surface of the overhang portion 6 is pressed against the upper surface of the step portion 7 to make a metal touch. At this time, the sealing agent 8a protruding from between the lower surface of the overhang portion 6 and the upper surface of the step portion 7 The bottom of the water jacket is sealed with a sealant 8 by a seal 8b remaining between the lower surface of the overhang portion 6 and the upper surface of the step portion 7 ((b) in FIG. 3). After drying, the sealant 8 hardens, and the cylinder liner 2 is more firmly fixed to the cylinder block 1.
[0016]
Next, the operation of the first embodiment of the present invention will be described.
A portion below the water jacket 4 around the upper portion of the cylinder liner 2 (below the lower surface of the overhang portion 6 of the liner 2) is a press-fit portion 3 at the lower end of the liner, and a clearance 5 above the press-fit portion 3 and below the water jacket. And the area below the water jacket on both the liner 2 side and the block 1 side is significantly larger than that of the conventional water jacket. Has been reduced.
[0017]
As a result, the processing cost of the press-fit processing section 3 is greatly reduced on both the liner 2 side and the block 1 side.
In addition, since the clearance 5 is provided in the majority of the fitting portion between the cylinder block 1 and the cylinder liner 2, deformation (enlargement and deterioration of roundness) of the cylinder bore during operation of the internal combustion engine (at high temperature) is suppressed.
As for the seal, the entire bottom of the water jacket 4 is filled with the sealant 8, so that the seal and the seal can be surely performed. Further, since the rubber O-ring is not used for the seal, the thermal durability and thermal reliability of the seal are improved.
[0018]
In addition, the following functions and effects are obtained by forming the cylinder liner 2 as a separate body.
The defective rate of the cylinder block 1 is reduced. In other words, the specification of the cavity of the cylinder block is strict with respect to the upper surface of the block around the cylinder bore, and the cavity may be relatively large in the block portion other than the bore. If the standard of the cavity is maintained strict as before, the standard of the cavity of the cylinder block 1 can be relaxed as compared with the conventional case, thereby reducing the defective rate of the cylinder block 1.
[0019]
In addition, the life of the cylinder block casting mold is improved, and the productivity of cylinder block casting is improved. In the past, the water jacket core was thin and the mold life was shortened, resulting in an increase in cost. However, since the cylinder liner 2 is a separate type, the water jacket type is integrated with the bore type, eliminating the need for a water jacket core on the back of the liner. And the mold becomes large and the mold life is prolonged. Also, the core exchange setup is reduced and the productivity of cylinder block casting is increased.
[0020]
Also, module design is possible. That is, the specification for increasing the displacement and the specification for increasing the bore diameter can be performed only by changing the cylinder liner 2, and the cylinder block 1 can be commonly used.
Further, the width of the water jacket 4 (the thickness of the water jacket 4 in the bore radial direction) can be reduced. Conventionally, the water jacket width had to be set to a predetermined value or more from the mold life of the water jacket core. However, in the present invention, since the mold life is not relevant, it is necessary to determine the width of the water jacket 4 to a dimension necessary for cooling. As a result, the width of the water jacket 4 can be reduced, and the cylinder block 1 can be made more compact.
In addition, since the cylinder liner 2 is a single type (not a multiple type), the cooling water can be supplied between the cylinder bores, and the space between the bores can be sufficiently cooled.
[0021]
Next, a second embodiment of the present invention will be described with reference to FIG.
In the second embodiment of the present invention, the press-fit portion 3 of the first embodiment of the present invention is a threaded portion 3A.
In the second embodiment of the present invention, a machined threaded portion 3A is provided on the outer peripheral surface 21 of the lower end of the cylinder liner 2 and the inner peripheral surface 11 of the cylinder block 1 corresponding to the lower end. The outer peripheral surface 21 and the inner peripheral surface 11 of the cylinder block 1 are screwed together. The positioning of the cylinder liner 2 with respect to the cylinder block 1 is performed by the threaded portion 3A. Since the positioning accuracy of the threaded portion 3A is lower than that of the press-fitted portion 3, the inner surface of the cylinder liner 2 may be honed after the cylinder liner 2 is screwed into the cylinder block 1.
Other configurations and operations are the same as those of the first embodiment of the present invention.
[0022]
【The invention's effect】
According to the fixing structure of the cylinder liner to the cylinder block according to the first aspect, a portion below the water jacket around the upper portion of the cylinder liner, a press-fit portion at the lower end of the liner, and a portion above the press-fit portion and below the water jacket. Since it is composed of the clearance portion and the liner side and the block side, the area of the press-fit portion can be greatly reduced. In addition, since the clearance portion is provided, most of the clearance between the cylinder block and the cylinder liner has a clearance, so that bore deformation (enlargement and deterioration of roundness) during operation (at high temperature) can be suppressed.
According to the structure for fixing the cylinder liner to the cylinder block according to the second aspect, the area of the threaded portion can be significantly reduced on both the liner side and the block side. In addition, since the clearance portion is provided, most of the clearance between the cylinder block and the cylinder liner has a clearance, so that bore deformation (enlargement and deterioration of roundness) during operation (at high temperature) can be suppressed.
According to the fixing structure of the cylinder liner to the cylinder block according to the third aspect, the bottom portion of the water jacket is sealed with the sealant at the portion supported by the step portion of the projecting portion, so that the durability of the seal can be improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a structure for fixing a cylinder liner to a cylinder block according to Embodiments 1 and 2 of the present invention.
FIG. 2 is a plan view of a fixing structure of a cylinder liner to a cylinder block according to Embodiments 1 and 2 of the present invention.
FIG. 3 is a cross-sectional view of a support portion of the cylinder liner overhanging portion of the cylinder liner overhang portion according to the first and second embodiments of the present invention, which is supported by the cylinder block step portion, and the vicinity thereof (A portion in FIG. (A) is a view before mounting the cylinder liner, and (b) is a view after mounting the cylinder liner.
FIG. 4 is a cross-sectional view (a cross-sectional view of a portion B in FIG. 1) of the press-fit processing portion and its vicinity in the structure for fixing the cylinder liner to the cylinder block according to the first embodiment of the present invention.
FIG. 5 is a cross-sectional view (a cross-sectional view of a portion B in FIG. 1) of a threaded portion and its vicinity in a structure for fixing a cylinder liner to a cylinder block according to a second embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Cylinder block 2 Cylinder liner 3 Press-in processing part 3A Thread processing part 4 Water jacket 5 Clearance 6 Overhang part 7 Step part 8 Sealant 8a Sealant 8b protruding from between the overhang part and the step part Between the overhang part and the step part Sealant 11 remaining on the inner surface 12 of the cylinder block inner peripheral surface 21 of the cylinder block facing the clearance outer peripheral surface 22 of the lower end of the cylinder liner outer surface of the cylinder liner facing the clearance

Claims (3)

The cylinder liner is separate from the cylinder block,
A press-fit processing portion is provided at a lower end position of the cylinder liner, and positioning of the cylinder liner with respect to the cylinder block is performed only by the press-fit processing portion,
Above the press-fit portion, and below a water jacket around the top of the cylinder liner, a radial clearance is provided between the cylinder liner and the cylinder block.
Fixing structure of cylinder liner to cylinder block. The cylinder liner is separate from the cylinder block,
A screw portion is provided at a lower end position of the cylinder liner, and positioning of the cylinder liner with respect to the cylinder block is performed only by the screw portion,
Above the screw portion, and below a water jacket around the top of the cylinder liner, a radial clearance is provided between the cylinder liner and the cylinder block.
Fixing structure of cylinder liner to cylinder block. At a portion corresponding to the bottom of the water jacket, an overhang is provided on the cylinder liner and a step is provided on the cylinder block, and a sealing agent is provided at a portion of the overhang supported by the step. The structure for fixing a cylinder liner to a cylinder block according to claim 1 or 2, wherein a bottom portion of the water jacket is sealed.

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