This non-provisional application incorporates by reference the subject matter of Application No. 2003-431207 filed in Japan on Dec. 25, 2004, on which a priority claim is based under 35 U.S.C. §119(a).
1. Field of the Invention
The present invention relates to an engine cylinder liner construction in which a cylinder liner is cast into a cylinder block, and more particularly to an engine cylinder liner construction in which projections are formed on an outer surface of the cylinder liner so as to strengthen the adhesion properties of the cylinder liner to the cylinder block.
2. Description of the Related Art
There have been adopted lots of engines in which a cylinder block main body is made of aluminum alloy with a view to reducing the weight thereof. Incidentally, in the aluminum alloy-made cylinder block of this type, in many cases, separate cylinder liners of cast iron or steel alloy are integrally cast into the cylinder block at the time of producing a cylinder block main body with a view to increasing wear resistance against pistons. In this case, cylinder liners are cast or pressed into the cylinder block. An example of such a pressing process is disclosed in JP-UM-A-3-89955.
Incidentally, in a case where the casting process is adopted to produce engines in which cylinder liners are cast into a cylinder block, when casting cylinder liners made of a different material into the cylinder block, due to the difficulty in making the cylinder block to completely adhere to the cylinder liners at the time of producing a cylinder block main body, minute gaps are produced between the cylinder block and the cylinder liners with time, and there are caused problems of reduction in accuracy of the roundness of the cylinder liner and of reduction in cooling performance thereof.
In a cylinder block disclosed in JP-A-2002-97998, for example, the adhesion properties of cylinder liners to a cylinder block are attempted to be secured by casting into the cylinder block cylinder liners each having a large number of spines or prickles which are formed on an outer surface thereof. Note that in this cylinder block, spines are eliminated between the adjacent cylinder liners so as to suppress the casting failure in facing gaps between the adjacent cylinder liners to thereby prevent the reduction in rigidity.
Incidentally, a cylinder head is superposed on the cylinder block via a gasket, and both the cylinder head and the cylinder bock are fastened together with bolts. As this occurs, in the cylinder block 100 shown in
As shown in
The invention was made based on the problem, and a primary object thereof is to provide an engine cylinder liner construction which can suppress the generation of a crack in the vicinity of an end portion of a joint portion between the casting portion of the cylinder block and the cylinder liner having spines to thereby prevent the reduction in sealing properties of combustion gases.
A secondary object of the invention is to provide an engine cylinder liner construction which can ensure the suppression of the generation of a crack in the vicinity of an extended portion on a cylinder block main body side to thereby prevent the reduction in sealing properties due to a damage to a cylinder gasket when applied to a cylinder block into which a cylinder liner having projections is cast while an end portion of the cylinder liner which faces the cylinder head is covered with the extended portion from the cylinder head side.
According to a first aspect of the invention, there is provided an engine cylinder liner construction in which a cylinder liner that is cast into a cylinder block has a tubular portion and a large number of spines integrally formed on an outer surface of the tubular portion, the engine cylinder liner construction comprising, a chamfered portion formed at an end portion of the tubular portion which faces a cylinder head by chamfering the end portion together with the spines located thereat.
According to a second aspect of the invention, there is provided an engine cylinder liner construction in which a cylinder liner that is cast into a cylinder block has a tubular portion and a large number of spines integrally formed on an outer surface of the tubular portion, and in which the cylinder liner is so cast while an end portion of the cylinder liner which faces a cylinder head adapted to be fastened to the cylinder block is being covered with an annular extended portion on the cylinder block side from the cylinder head side, the engine cylinder liner construction a chamfered portion formed at an end portion of the tubular portion which faces a cylinder head by chamfering the end portion together with the spines located thereat.
According to a third aspect of the invention, there is provided an engine cylinder liner construction as set forth in the first or second aspect of the invention, wherein the chamfered portion is such that an angle of inclination relative to a cylinder center line is set to be about 12° to 30°.
According to a fourth aspect of the invention, there is provided an engine cylinder liner construction as set forth in the first, second or third aspect of the invention, characterized in that a portion between the chamfered portion and an end face of the tubular portion which faces the cylinder head is rounded.
According to the first aspect of the invention, since the chamfered portion is formed at the end portion of the tubular portion positioned in the vicinity of the end portion of the joint portion between the cylinder block and the cylinder liner or positioned on the cylinder head side by chamfering the end portion together with the spines located thereat in a tapered fashion, the spines located in the vicinity of the end portion of the joint portion can be removed so as to suppress the generation of a crack from the spines to thereby suppress the generation of damage to the cylinder gasket due to a crack that would otherwise be generated, thereby making it possible to ensure the prevention of reduction in sealing properties between the cylinder block and the cylinder head.
According to the second aspect of the invention, since the chamfered portion is formed at the end portion of the tubular portion positioned in the vicinity of the end portion of the joint portion between the cylinder block and the cylinder liner or positioned on the cylinder head side by chamfering the end portion together with the spines located thereat in a tapered fashion, the spines located in the vicinity of the extended portion which covers the end portion of the cylinder liner which faces the cylinder head can be removed so as to suppress the generation of a crack from the spines in the vicinity of the extended portion to thereby suppress the generation of damage to the cylinder gasket due to a crack that would otherwise be generated, thereby making it possible to ensure the prevention of reduction in sealing properties between the cylinder block and the cylinder head.
According to the third aspect of the invention, since the angle of inclination of the chamfered portion formed at the end portion of the tubular portion is set to be about 12° to 30°, when the fastening load, which varies to be increased or decreased in accordance with a variation in the gas pressure, is applied to the chamfered portion via the extended portion, a component of the fastening load which is divided in a radial direction of a cylinder is suppressed to thereby suppress, in turn, an inclined displacement of the end portion of the joint portion of the tubular portion to the cylinder block into the interior of the cylinder, and moreover, since the spines are cut within a range where a cut with of the chamfered portion in an axial direction of the cylinder does not become too large, the reduction in adhesion properties between the tubular portion and the cylinder block can be prevented.
According to the fourth aspect of the invention, since the chamfered portion and the end face of the tubular portion which faces the cylinder head are rounded so as to eliminate any edge-like shape thereat, the generation of a crack in the extended portion in the vicinity of the rounded overlapping portion R can be prevented in an ensured fashion, in particular, together with the advantage of the formation of the chamfered portion at the end portion of the tubular portion which faces the cylinder head by chamfering the end portion together with the spines located thereat, the generation of a crack in the vicinity of the end portion of the joint portion between the tubular portion and the cylinder block can be prevented in a more ensured fashion.
A gasoline engine (hereinafter, simply referred to as an engine) 2 adopting a cylinder block to which a cylinder liner construction as an embodiment of the invention is applied is shown in
A main body of the engine 2 has a cylinder block 3 into which a cylinder liner 1 is cast, a cylinder head 4 and a head cover, not shown, which are sequentially connected together to an upper side of the cylinder block 3 in that order and an oil pan 6 which is integrally connected to a lower side of the cylinder block 3. The engine 2 is a multi-cylinder engine having a plurality of cylinders S which are formed into the same configuration, a piston 7 is disposed in each cylinder S in such a manner as to slide vertically, and a combustion chamber is defined by the cylinder liner 1, the piston 7 and a lower wall of the cylinder head 4 in such a manner that the capacity thereof can be changed.
A gasket 5 is disposed between the cylinder block 3 and the cylinder head 4, which is placed on the upper side of the cylinder block 3, and the cylinder block 3 and the cylinder head 4 are strongly and integrally fastened together by tightening head bolts, not shown, with the gasket 5 being held therebetween. A fuel supply system, intake and exhaust systems and a valve driving system or a valve train, which are all not shown, are mounted on the cylinder head 4, whereby the flow control of fuel supplied to the combustion chamber C in each cylinder, intake gas drawn into the combustion chamber C and exhaust gas exhausted from the combustion chamber C can be implemented.
In the cylinder block 3 to which the engine cylinder liner construction according to the invention is applied, a plurality of cylinders S are disposed in a straight line along a longitudinal direction X of the series of cylinders (refer to
The cylinder block 3 is cast using a high-pressure die casting method in which a molten aluminum alloy is cast into a mold under high pressure, and cast together are a cylinder block main body 8, a plurality of cylinder liners 1 which are cast into the cylinder block main body 8, the water jacket 9 formed to surround the outer circumferential portions of the respective cylinders s, the external wall portion 15 which surrounds the outer circumference of the water jacket 9 so formed and a crankcase 19 which constitutes a lower portion of the cylinder block main body 8.
Each cylinder S in the cylinder block 3 is made up of the cylinder liner 1 and a casting portion 11 on the cylinder block main body 8 side into which the entirety of an outer surface of the cylinder liner 1 is cast. Here, the whole area of the outer surface of the cylinder liner 1 is cast by the casting portion 11 while an end portion m of a joint portion between the cylinder liner 1 and the casting portion 11 which is situated at an upper end in a vertical direction Y constituting a direction of the axis L of the cylinder and which faces the cylinder head 4 is being covered with an extended portion 14 which is caused to extend from the casting portion 11 via a neck portion n.
The extended portion 14 caused to extend from the upper end of the casting portion 11 towards the axis L of the cylinder is formed in such a manner as to cover the joined end portion m constituting an upper end of a tubular portion 12 in an annular fashion from the cylinder head 4 side. Upper wall surfaces fb of the casting portion 11 and the extended portion 14, which are both situated on the cylinder block 3 side, are formed in such a manner as to be situated on the same plane and to protrude in the vertical direction Y, which constitutes the direction of the axis L of the cylinder by an extended width d (refer to
The cylinder liner 1 contains cast iron and is cast as a cylinder liner, and more particularly, as a spiny liner including the tubular portion 12 and a large number of spines 13 as projections which are provided on an outer surface of the tubular portion 12 in such a manner as to protrude therefrom, whereby the adhesion properties of the cylinder liner 1, which is the spiny liner, to the casting portion 11 is ensured. As shown in
The cylinder liner 1 is chamfered by a tapered cut surface fc where the joined end portion m of the cylinder liner 1, which is the upper end portion thereof in the vertical direction which faces the cylinder head 4, and the spines 13 (indicated by double-dashed chain lines in
In contrast, in the event that the cut width B in the vertical direction Y is too large, the adhesion properties between the casting portion 11 on the cylinder block 3 side and the vicinity of the joined end portion m of the cylinder liner 1 are reduced, whereas in the event that cut width B is too small, the protruding end of the spike 13 comes too close to the neck portion n of the extended portion 14, whereby the function to suppress the generation of a crack is deteriorated. Due to this, while the cut width B is experimentally set depending on cylinder liners 1, generally, the cut width B is set within a range of values which ranges from a value corresponding to the addition of the thickness A of the tubular portion 12 and the protruding width h of the spike 13 to a value on the order of two times larger than the value resulting from the addition.
Furthermore, while the angle of inclination of the tapered cut surface fc is set to 15°, this value desirably ranges within 3° plus or minus from 15°, and the angle of inclination may range between 12° to 30° as the case may be, the reason for this being described below.
The fastening load W is applied from the extended portion to the tapered cut surface fc and the upwardly oriented surface fh of the joined end portion m of the tubular portion 12 which follows the tapered cut surface fc. Of the fastening load W so applied, a fastening load W applied to the tapered cut surface fc is, as shown in
Here, in the event that the fastening load W is applied when the angle of inclination is 45°, the divided component ws in the radial direction of the cylinder is relatively large and the inclined displacement of the joined end portion m of the tubular portion 12 towards the axis L of the cylinder is facilitated, whereby the possibility is increased that the relative displacement between the upper end of the casing portion 11 and the extend portion 14 is enhanced.
In contrast to this, in the event that the angle of inclination is reduced from 45°, the divided component ws in the radial direction of the cylinder becomes relatively small, the inclined displacement of the joined end portion m of the tubular portion 12 towards the axis L of the cylinder can be suppressed. In case the angle of inclination is too small, or in case the angle is set to a value which is smaller than 12°, for example, however, the cut width B from the joined end portion m becomes excessively large, and as this occurs, the reduction in adhesion properties of the casing portion 11 on the cylinder block 3 side to the vicinity of the joined end portion m of the cylinder liner 1 is facilitated.
On the contrary, in case the angle of inclination becomes excessively large (for example, 80°), the cut width B from the joined end portion m becomes excessively small, and as this occurs, the protruding end of the spike 13 comes too close to the main part of the casting portion 11 and the neck portion n of the extended portion 14 which continues therefrom, whereby the crack generation suppressing function is deteriorated. Due to this, the angle of inclination is desirably in the range of 3° plus and minus from 15°, and when the angle of inclination is in the range of 12° to 30°, the protruding end of the spike 13 is refrained from coming close to the neck portion n, whereby a risk is eliminated that the cut width B is increased excessively to thereby cut the spike 13, the adhesion properties of the casting portion 11 to the joined end portion m of the cylinder liner 1 being thereby deteriorated.
Furthermore, in the joined end portion m of the tubular portion 12 of the cylinder liner 1, the overlapping portion R between the tapered cut surface fc and the upwardly oriented surface fh which follows the tapered cut surface fc and faces the cylinder head is rounded or radiused. By radiusing the overlapping portion R, the stress is attempted to be dispersed at the neck portion n of the extended portion 14 which faces the overlapping portion R, whereby the generation of a crack in the vicinity of the neck portion n is suppressed as well. Thus, the joined end portion m of the tubular portion 12 and the spikes 13 located in the joined end portion m are chamfered by the tapered cut surface fc, and in addition to this, the overlapping portion R between the tapered cut surface fc and the upwardly oriented surface fh is radiused, whereby the generation of a crack in the neck portion n in the vicinity of the joined end portion m can be prevented in a further ensured fashion.
In the engine 2 utilizing the cylinder block 3 to which the invention is applied, the cylinder head 4 and the cylinder block 3 are fastened to each other by head bolts with the gasket 5 being held therebetween, whereby the gas tightness at the joint surface between the cylinder head 4 and the cylinder block 3 is secured by the predetermined fastening load W applied to the joint surface. When the engine 2 is running, the combustion pressure in the combustion chamber C changes in an intermittent fashion, and in association with the change, the fastening load W changes to rise and fall, whereby the press contact state between the upper wall surfaces fb of the external wall portion 15 in the vicinity of the upper wall side of the cylinder block 3, the casting portion 11 and the extended portion 14 and the cylinder head 4 via the gasket 5 changes. As this occurs, the fastening load W from the main part of the extended portion 14 is borne by the upwardly oriented surface fh of the tubular portion 12 in the vertical direction. In contrast, the fastening load W borne by the neck portion n of the extended portion 14 is applied to the tapered cut surface fc, as shown in
Furthermore, since the joining properties between the casting portion 11 and the spikes 13 which constitute the outer surface of the tubular portion 12 are held strongly, the relative displacement between the casting portion 11 and the spikes 13 is eliminated, and the relative displacement between the upper ends of the joined end portion m and the casting portion 11 which are situated thereabove and the neck portion n is also eliminated. In particular, since the spikes 13 in the casting portion 11 are removed over the cut width B from the vicinity of the neck portion n, the generation of a crack (refer to reference numeral 170 in
Thus, in the cylinders S in the cylinder block 3 to which the cylinder liner construction of the invention is applied, the casting portion 11 and the cylinder liner 1 having the spikes 13 on the outer surface thereof are caused to adhere to each other strongly, and the extended portion 14 is provided on the casting portion 11 via the neck portion n, whereby the gasket 5 is prevented from facing the joint surface F directly, so that the reduction in sealing properties between the cylinder block 3 and the cylinder head 4 can be prevented in an ensured fashion.
Moreover, in particular, the tapered cut surface fc is formed at the inclination angle over the cut width B so as to remove the spikes 13, and the overlapping portion R between the tapered cut surface fc and the upwardly oriented surface fh is radiused, whereby, in the event that the fastening load W is applied from the cylinder head 4 side, the generation of a crack in the vicinity of the neck portion n is prevented in an ensured fashion, whereby the reduction in sealing properties, which would otherwise occur if a crack were generated to reach the upper wall surfaces fb of the casing portion 11 and the extended portion, is prevented. Thus, by this construction, the reduction in sealing properties between the cylinder block 3 and the cylinder head 4 can also be prevented in an ensured fashion.
In the cylinder block 3 shown in
In this case, a tapered cur surface fc is formed in a joined end portion m of a cylinder liner 1a, and the joined end portion m is cast by an inner expanded portion 111 at an upper end of a casting portion 11a, whereby a main part of the casting portion 11a, the inner expanded portion 111 and the joined end portion m are brought into a press contact with a lower wall surface of a cylinder head 4 via a gasket 5. Also, here, as has been described with reference to
Thus, as with the cylinder S shown in
In the cylinder block 3a shown in
In this case, the tapered cut surface fc, the radiused stepped portion 121 and a tubular end portion 122 are formed over the cut width B in a joined end portion m of a cylinder liner 1b, and the joined end portion is cast by an inner expanded portion 112 at an upper end of the casting portion 11b, whereby a main part of the casting portion 11b, the inner expanded portion 112 and the joined end portion m are brought into a press contact with the lower wall surface of the cylinder head 4 via the gasket 5. Also, here, as has been described with reference to
Also with this cylinder block 3b, a substantially similar function and advantage to that obtained by the cylinder block 3a shown in
As has been described heretofore, while the cylinder block used in the engine cylinder liner construction is described as being cast in such a manner as to cast the cylinder liner thereinto using the high-pressure die casting method, the invention can be applied in a similar fashion to an engine cylinder block into which cylinder liners are cast using a gravity casting method.
Number | Date | Country | Kind |
---|---|---|---|
P 2003-431207 | Dec 2003 | JP | national |
Number | Name | Date | Kind |
---|---|---|---|
1437904 | Moomaw | Dec 1922 | A |
1896098 | Poyer | Feb 1933 | A |
2062394 | Brown | Dec 1936 | A |
2126089 | Brown | Aug 1938 | A |
3165983 | Thomas | Jan 1965 | A |
5050547 | Takahashi | Sep 1991 | A |
5199166 | Torigai et al. | Apr 1993 | A |
6640765 | Land et al. | Nov 2003 | B2 |
6925981 | Ibukuro et al. | Aug 2005 | B2 |
Number | Date | Country |
---|---|---|
3-89955 | Sep 1991 | JP |
2002-97998 | Apr 2002 | JP |
Number | Date | Country | |
---|---|---|---|
20050161014 A1 | Jul 2005 | US |