JP3161301B2 - Cylinder liner for cast-in - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder liner for a cast-in body, which forms a cylinder structure by casting an outer peripheral portion of a liner body with a casting material.

[0002]

2. Description of the Related Art When a cylinder block of an automobile engine is a cast product made of, for example, an aluminum alloy, the cylinder bore portion where the piston slides repeatedly is subjected to seizure resistance against sliding friction, scuff resistance, abrasion resistance, rigidity, and the like. Therefore, a cylinder liner made of a material that can cope with these is used. As one means for integrating the cylinder liner and the block portion, a cylinder liner is set in a mold when a cylinder block is cast, and an outer peripheral portion of the cylinder liner is cast material (aluminum alloy). There is known a method of casting in.

[0003] As a conventional cylinder liner for cast-in, there is known a technique disclosed in Japanese Utility Model Laid-Open No. 1-105065. In this technique, a spiral groove is formed on the outer peripheral surface of the cylinder liner, and the spiral angle and pitch of the spiral groove are set so as to prevent relative rotation between the cylinder liner and the block portion after casting. I have.

[0004]

When casting a cylinder block, the molten metal is usually poured into the mold from below, but the molten metal flows along the axis of the cylinder liner. Therefore, on the outer periphery of the cylinder liner, the spiral groove is positioned obliquely to the flow direction of the molten metal, and the molten metal does not sufficiently enter the inside (bottom) of the spiral groove.
As a result, a gap is generated between the cylinder liner and the casting material (block portion), and mutual adhesion is reduced. Also, when the dimension between adjacent cylinder liners is reduced to shorten the entire length of the cylinder block, the casting material between the cylinder liners may contract and move in the process of solidification and contraction after casting and crack.

It is an object of the present invention to provide a space between adjacent liner bodies.
Between the casting material in the narrowest part and the outer peripheral surface of the liner body.
To improve the adhesion and the solidification shrinkage of the casting material in this area.
The purpose of the present invention is to prevent the casting material from cracking by dispersing the tensile stress .

[0006]

SUMMARY OF THE INVENTION The present invention relates to a mold for casting.
The outer periphery of the multiple liner bodies set in
A cylinder cylinder liner for assembling to form a cylinder structure by squeezing, only in the portion of the outer peripheral surface of the liner body that is closest to the adjacent liner body,
Protrusions or grooves extending along the axis of the liner body
Wherein the but has been eclipsed set. Adjacent like this
Casting material narrowest portion interval of the liner body with molten metal enters write Mukoto in between or grooves of the protrusions, casting material
And the outer surface of the liner body have increased adhesion.
Of tensile stress due to solidification shrinkage of cast material in
Cracking of the casting material is prevented .

[0007]

[0008]

[0009]

Embodiments of the present invention will be described below. FIG. 1 shows the structure of a cylinder liner for assembling, FIG. 1 (A) is a perspective view showing the structure of a liner main body 2, and FIG. 1 (B) is an expanded view thereof. This liner body 2
Has a cylindrical shape, and a groove 10 is formed on the outer peripheral surface 4 thereof. The groove 10 extends straight in the direction Z along the axis of the liner body 2 and is formed in a plurality in the circumferential direction of the liner body 2. Note that the left-right direction in FIG. 1B is a direction Yd in which a tensile stress is generated at the time of solidification shrinkage of the casting material 30 described later.

FIG. 1C is a sectional view taken along line CC of FIG. 1B. The details of the groove 10 will be described with reference to this drawing. Each groove 10 is formed by machining so that its cross-sectional shape is substantially semicircular, and the radius R, depth H, and pitch P are determined by the material and size of the liner body 2 and the casting material 30, or Based on the casting conditions and the like, the adhesion between the liner body 2 and the casting material 30 is enhanced, and the casting material 30
Is set to the most effective value for preventing cracks. 1A and 1B, only a part of the groove 10 is shown and other parts are omitted. However, the groove 10 is actually formed over the entire outer peripheral surface 4 of the liner body 2. I have.

Next, a description will be given of a procedure for manufacturing a cylinder liner for insert molding. First, in manufacturing the liner body 2, the basic shape of the liner body 2 is formed by casting or extrusion. The cast product or the extruded product is subjected to internal grinding and end face processing, and the cast product is further subjected to external grinding to finish it into a predetermined cylindrical shape. As for the formation of each groove 10, the liner main body 2 manufactured as described above is held by a holding mechanism (not shown) rotatable around its central axis. Then, a cutting tool (not shown) is brought into contact with one point of the outer peripheral surface 4 of the liner body 2 to move the holding mechanism together with the liner body 2 in the direction Z along the axis of the liner body 2 shown in FIGS. Let it. Thereby, one groove 10 is formed. Subsequently, the liner main body 2 is rotated by a slight angle corresponding to the pitch P by the holding mechanism, and the next groove 10 is formed in the same manner as described above.
To form By repeating this operation until the liner body 2 makes one rotation, a plurality of grooves 10 are formed at a predetermined pitch P over the entire outer peripheral surface 4 in parallel with the direction Z along the axis of the liner body 2.

The cylinder block of the engine is manufactured by performing the insert using the insert cylinder liner having such a structure. In this production, first, a plurality of liner bodies 2 are set in a mold for a cylinder block, and a molten metal such as an aluminum alloy is poured into the mold from below. At this time, the molten metal flows in the direction Z along the axis of the liner main body 2, and since the flow direction of the molten metal is the same as the direction of the grooves 10 on the outer periphery of the liner main body 2, the molten metal reaches the inner bottom of each groove 10. (Casting material 30) penetrates sufficiently. As a result, the outer peripheral surface 4 of the liner main body 2 and the casting material 30 are in close contact with each other in a state where they are meshed with each other.

FIG. 2 is a plan view showing a part of the as-filled cylinder liner in the as-filled state. Here, FIG.
The block portion made of the casting material 30 shown in (A) is divided into a portion Xb in which the interval between two adjacent liner bodies 2 is the smallest, and a portion Xc located above and below the portion Xb in the drawing. When the volume of the casting material 30 poured during casting is reduced by cooling and solidification, the volume of the portion Xc is larger than that of the portion Xb, so that the amount of shrinkage also increases. For this reason, a tensile stress in the Yd direction is generated in the portion Xb of the casting material 30 at the time of solidification shrinkage.
As shown in (B), cracks 32 may occur. This crack 32 extends in the direction Z along the axis of the liner body 2 and may extend the entire length of the liner body 2. In order to prevent the crack 32, there is a means for increasing the distance Xa between two adjacent liner bodies 2 as shown in FIG. 2 (A). However, in this case, the entire length of the cylinder block becomes longer than necessary. .

In the present embodiment, since the adhesion between the outer peripheral surface 4 of the liner body 2 and the casting material 30 is enhanced as described above, the tensile stress in the Yd direction during cooling and solidification of the casting material 30 is increased. Are dispersed, and even if the distance Xa between two adjacent liner bodies 2 is reduced, the portion X of the casting material 30 is reduced.
The occurrence of the cracks 32 in b is prevented. In particular, since each of the grooves 10 is located substantially perpendicular to the direction Z along the axis of the liner body 2, that is, the direction Yd in which the stress occurs when the casting material 30 solidifies and contracts, the tensile stress in the Yd direction Can be more effectively dispersed and suppressed. In this way, the size of the entire cylinder block can be reduced by reducing the interval Xa while preventing the generation of the cracks 32.

The liner body 2 is formed by the grooves 10 described above.
That the adhesion between the outer peripheral surface 4 and the casting material 30 is improved.
During the operation of the engine, the casting material 30 is
The expansion in the circumferential direction (Yd direction) is suppressed. This function is more effective because each groove 10 is located in the direction Z along the axis of the liner main body 2. Therefore, it is possible to prevent a gap from being generated between the liner body 2 and the casting material 30 due to a difference in the coefficient of thermal expansion between the liner body 2 and the casting material 30 during the actual operation of the engine. Therefore, heat conduction from the liner main body 2 to the casting material 30 is improved, and the compression ratio during engine operation can be increased.

Groove 1 for outer peripheral surface 4 of liner body 2
The formation of 0 is performed by cutting using a cutting tool as described above, but other processing means can be used. FIG. 3 is a sectional view of a groove 16 formed by extrusion. Each groove 16 is formed by extruding a substantially trapezoidal cross section, and has a groove width L, depth H2, and pitch P
2. The inclination angle θ of the groove side surface increases the adhesion between the liner body 2 and the casting material 30 based on the material and size of the liner body 2 and the casting material 30, or the casting conditions, and reduces the crack 32. It is set to the most effective value for prevention.

A rib-shaped projection may be formed on the outer peripheral surface 4 of the liner main body 2 instead of the grooves 10 and 16. FIG.
4 is a sectional view of a projection 20 formed on the outer peripheral surface 4 of the liner main body 2. FIG. As in the case of the grooves 10 and 16, the projections 20 also extend straight in the direction Z along the axis of the liner main body 2 and are formed in a plurality in the circumferential direction of the liner main body 2. These projections 20 are also formed by cutting or extrusion. The width L2, height H3, pitch P3, and side surface inclination angle θ2 of each projection 20 are determined based on the material and size of the liner body 2 and the casting material 30, or the casting conditions, etc. Is set to the most effective value for enhancing the adhesiveness of the metal and preventing the crack 32.

In particular, the inclination angle θ2 is set such that the width L2 of each projection 20 is the maximum dimension on the outer peripheral side of the outer peripheral surface 4 of the liner main body 2. As a result, the casting material 30 that has entered between the projections 20 is held in close contact with the outer peripheral surface 4 of the liner main body 2 by the anchor effect. Therefore, when the engine is in operation, the casting material 3
0 is more effectively suppressed from expanding in the circumferential direction of the liner body 2, and the generation of a gap due to the difference in the coefficient of thermal expansion between the liner body 2 and the casting material 30 is almost certainly prevented.
The anchor effect can be exerted, for example, also in the groove 16. That is, by setting the inclination angle θ so that the width L shown in FIG. 3 is the minimum dimension on the outer peripheral side of the outer peripheral surface 4 of the liner main body 2, the casting material 30 and the liner main body 2 Is held in close contact with the outer peripheral surface 4 by the anchor effect.

The grooves 10, 16 and the projections 20 can be formed at the time of casting the liner body 2 in addition to cutting and extrusion. In other words, a convex shape corresponding to the grooves 10 and 16 or a concave shape corresponding to the protrusion 20 may be formed on the cavity surface of a mold for casting the liner body 2, and the liner body 2 may be cast using this mold. Also, after the liner body 2 is manufactured, the grooves 10, 16 and the projections 20 can be formed on the outer peripheral surface 4 by press working.

Further, the grooves 10, 16 and the projections 20 may be formed only in the portion of the outer peripheral surface 4 of the liner body 2 which is closest to the adjacent liner body 2. Even in such a case, for the portion Xb of the casting material 30 shown in FIG. 2A, the adhesion to the outer peripheral surface 4 of the liner body 2 is enhanced, and the tensile stress in the Yd direction during cooling and solidification of the casting material 30 is dispersed. And a crack 32 is formed in the portion Xb of the casting material 30.
Is prevented from occurring. However, if the grooves 10, 16 and the projections 20 are formed over the entire outer periphery 4 of the liner body 2, the adhesion to the casting material 30 can be improved over the entire outer periphery 4 of the liner body 2. That is, when setting the liner main body 2 in the mold at the time of casting of the cylinder block, the positioning is performed so that the grooves and projections formed on a part of the outer peripheral surface 4 are closest to the adjacent liner main body 2. There is no need to consider it.

[0021]

According to the present invention, it is possible to prevent the occurrence of a gap between the liner main body and the casting material, thereby improving the mutual adhesion, and to prevent the casting material between the liner bodies from cracking during the solidification shrinkage process after casting. Can be prevented.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a cylinder liner for insert molding.

FIG. 2 is a plan view showing a part of the as-filled cylinder liner in the as-filled state.

FIG. 3 is a cross-sectional view illustrating a groove formed by extrusion.

FIG. 4 is a sectional view showing a protrusion formed on the outer peripheral surface of the liner main body.

[Explanation of Signs] 2 Liner main body 4 Outer peripheral surface 10, 16 Groove 20 Projection 30 Casting material

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-58-17304 (JP, A) JP-A-56-147329 (JP, U) JP-A-53-75604 (JP, U) (58) Field (Int.Cl. ⁷ , DB name) B22D 19/00 B22D 19/08 F02F 1/08

Claims (1)

(57) [Claims] An as-cast cylinder liner for forming a cylinder structure by casting an outer peripheral portion of a plurality of liner bodies set in a mold during casting with a casting material. Adjacent liner bodies on the outer circumference of the body
Closest part only, insert casting cylinder liners, characterized in that the projections or grooves extending in a direction along the axis of the liner body is kicked set to.