JP2007270812A - Piston for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piston for an internal combustion engine capable of easily forming a cooling channel, and accurately and easily joinable by bringing interface surfaces into close contact with each other. <P>SOLUTION: This piston for the internal combustion engine has an annular passage 17a of the cooling channel 17 inside a head part 11, and is formed by joining a piston body 18 having a skirt part 12 having a boss 13 and a central part 11a of the head part 11, and a head annular part 11c forged with a land part 14 having a piston ring groove 15 and a peripheral edge part 11e of the head part 11, in the interface surfaces 11d and 18d. The interface surfaces 11d and 18d are formed of a single tapered surface crossing the annular passage 17a of the cooling channel 17 and inclined so that an end part on the central part 11a side more than an end part on the peripheral edge part 11e side, approaches a top surface 11b. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a piston used in an internal combustion engine such as a diesel engine, a reciprocating engine such as a gasoline engine, and more particularly to an internal combustion engine provided with a cooling channel for cooling that circulates a coolant such as lubricating oil inside a head portion. Related to pistons.

  A piston for an internal combustion engine such as a reciprocating engine has a head portion and a skirt portion. The head portion has a top surface facing the combustion chamber and a piston ring groove, and a land portion facing the cylinder. The piston is formed in the skirt portion. A boss into which a pin is inserted is provided.

  In such a piston, different performance is required for each part. For example, the top surface of the head part is required to have heat resistance because heat at the time of combustion is directly transmitted, and the land part of the head part and the piston Since the ring groove slides in the cylinder and comes into contact with the piston ring that receives a high combustion pressure, high wear resistance and body surface pressure resistance are required, and the boss portion of the skirt portion is required to have high surface pressure resistance.

  Conventionally, in order to achieve such different performances, different materials have been used for each part. For example, in order to ensure the heat resistance strength of the head portion at high temperature, as described in Patent Document 1, a rapidly solidified powder aluminum alloy, a fiber reinforced aluminum alloy, particles on the top surface side of the head portion or a part thereof Forming by forging using a reinforced aluminum alloy or the like, or disposing a Ni-resist ring in a piston ring groove, particularly a pressure ring groove, has been performed.

  In addition, in order to cool the head portion, for example, as described in Patent Documents 2 and 3 below, a device in which a cooling channel serving as a cooling oil flow path is provided inside the head portion has been proposed. .

In these Patent Documents 2 and 3, the piston for the internal combustion engine is composed of an upper forming body and a lower forming body, and a cooling cavity is formed between the upper forming body and the lower forming body, so that the inside of the head portion is formed. An annular cooling cavity is provided.
JP-A-9-310639 Japanese Utility Model Publication No. 6-25537 JP 2000-230458 A

  However, in Patent Document 1 in which materials are made different between the lower part and the upper part of the head part using a rapidly solidified powder aluminum alloy containing silicon carbide in the upper part of the head part, different materials are forged at a high pressure. Therefore, it is difficult to provide a cooling cavity inside the head, and the strength cannot be improved while improving the cooling performance.

  On the other hand, in Patent Documents 2 and 3 provided with cooling cavities, the joint surface between the upper formation body and the lower formation body of the piston is a horizontal plane from the land portion to the cooling cavity, and from the cooling cavity to the top of the head portion. Therefore, it is not easy to join the upper forming body and the lower forming body with high accuracy. That is, when formed with a plurality of surfaces as described above, one joining surface having a smaller tolerance contacts, so that the joining accuracy of the other joining surface deteriorates and all the joining surfaces are joined with sufficient accuracy. It was difficult.

  Accordingly, an object of the present invention is to provide a piston for an internal combustion engine that can easily form a cooling channel, and at the same time, allows the joining surfaces to be in close contact with each other and can be joined with high accuracy.

  In order to solve the above-mentioned problems, the invention according to claim 1 is directed to an internal combustion engine piston having a cooling channel annular passage inside a head portion, and a skirt portion having a boss formed with a piston pin hole and the head portion. A piston body integrally provided with a central portion thereof, a land portion having a piston ring groove, and a head annular portion forged integrally with a peripheral portion of the head portion are joined at a joining surface, and the joining is performed. The surface is formed of a single tapered surface that traverses the annular channel of the cooling channel and is inclined so that the end on the center side is closer to the top surface than the end on the peripheral edge side. And

  According to a second aspect of the present invention, in addition to the configuration of the first aspect, the head portion has a cavity on the top surface, and the head annular portion includes a lip portion that protrudes inside the cavity. It is characterized by that.

  According to a third aspect of the invention, in addition to the configuration of the second aspect, the head annular portion includes an outer peripheral portion having the land portion and an inner peripheral portion having the lip portion, and the outer peripheral portion. And the inner peripheral portion are made of different materials, the outer peripheral portion has higher wear resistance than the inner peripheral portion, and the inner peripheral portion has higher heat resistance than the outer peripheral portion.

  According to a fourth aspect of the present invention, in addition to the configuration according to any one of the first to third aspects, the head annular portion is made of a material having higher heat resistance than the piston body.

  According to a fifth aspect of the present invention, in addition to the configuration according to any one of the first to fourth aspects, the head annular portion is formed by forging a rapidly solidified alloy.

  The invention according to claim 6 is characterized in that, in addition to the structure according to any one of claims 1 to 5, the piston body is forged.

  According to a seventh aspect of the present invention, in addition to the configuration according to any one of the first to sixth aspects, the cooling channel is formed from the annular path toward the top surface of the head annular portion. An extension path comprising end holes is provided, and a plurality of the extension paths are arranged at predetermined intervals in the circumferential direction of the piston.

  According to an eighth aspect of the present invention, in addition to the configuration according to any one of the first to seventh aspects, the cooling channel is arranged in the direction of the piston axis in addition to the annular path traversed by the joint surface. The other annular path formed in the part is provided, The two said annular paths are connected by the bypass path, It is characterized by the above-mentioned.

  According to the piston for an internal combustion engine according to claim 1, since the joint surface between the piston main body and the head annular portion is formed so as to cross the annular channel of the cooling channel, the annular channel can be opened to the joint surface. The annular path can be easily formed from the joint surface side. Therefore, it is possible to form an annular path at the same time when the head annular portion is forged, and manufacturing is easy.

  Further, since the joining surface is formed by a single tapered surface, the tolerance can be kept small over the entire joining surface, and the joining surfaces are easily brought into close contact with each other and can be easily joined with high accuracy. In addition, if the start point and the end point of the joint surface are not changed, the joint surface can be made the shortest distance and the joining can be performed more easily and accurately, and at the same time, the volume of the head annular portion can be reduced. It is easy to form the head annular portion by forging.

  According to the piston for an internal combustion engine according to claim 2, the head annular portion includes the land portion having the piston ring groove and the lip portion protruding inside the cavity of the top surface of the head portion. The lip portion, which is a portion that requires high performance, and the land portion, which is a portion that requires high wear resistance and surface pressure resistance, can be integrated into the head annular portion, and the durability of the piston can be easily improved.

  According to the piston for an internal combustion engine according to claim 3, the head annular portion has an outer peripheral portion having a land portion and an inner peripheral portion having a lip portion, and the outer peripheral portion and the inner peripheral portion are different materials. The outer peripheral part is made of a material that has higher wear resistance than the inner peripheral part, and the inner peripheral part is made of a material that has higher heat resistance than the outer peripheral part. It is possible to ensure the wear resistance of the part where the head is likely to occur, and it is easy to improve the durability of the head annular portion.

  According to the piston for an internal combustion engine according to claim 4, since the head annular portion is made of a material having a higher heat resistance than the piston main body, it is possible to ensure the heat resistance strength of the portion that is likely to become higher in temperature and to improve the durability. Easy to do.

  In addition, since the head annular portion is divided from the piston main body by a joint surface comprising a single tapered surface, the volume of the head annular portion can be kept small, and the amount of material having higher heat resistance strength than the piston main body is reduced. It is possible to suppress.

  According to the piston for an internal combustion engine according to claim 5, since the head annular portion particularly required for heat resistance and wear resistance is forged from a rapidly solidified alloy, the durability of the head annular portion is improved. It can certainly improve.

  According to the piston for an internal combustion engine according to claim 6, since the piston main body and the head annular portion having the joint surfaces crossing the annular path of the cooling channel are respectively formed by forging, the cooling channel is formed inside the head portion. Even if it is provided, it is possible to form the piston with sufficient strength.

  Moreover, the wall thickness can be reduced due to forging, the passage cross-sectional area of the cooling channel can be increased, and the weight of the entire piston can be reduced.

  According to the piston for an internal combustion engine of the seventh aspect, the cooling channel includes an extension path including an end hole bored from the head annular portion toward the top surface of the head annular portion, and the extension path is provided on the piston. Since a plurality of them are arranged at predetermined intervals in the circumferential direction, it is easier to cool the top surface side of the head portion that is particularly easily heated.

  According to the piston for an internal combustion engine according to claim 8, in addition to the annular path crossed by the joint surface, the other annular path formed in the head annular part is provided, so that the head part is cooled by the plurality of annular paths. And efficient cooling is possible.

[Embodiment 1]
Embodiment 1 of the present invention will be described below with reference to the drawings.

  1 to 6 show a piston for a direct injection diesel engine according to the first embodiment. In the figure, reference numeral 10 denotes a piston, which has a head portion 11 arranged on the combustion chamber side of a cylinder (not shown) and a skirt portion 12 arranged on the crank side (not shown). The skirt portion 12 is provided with a boss 13 having a piston pin hole 13 a, and a land portion 14 having three piston ring grooves 15 is provided on the side peripheral surface side of the head portion 11. The top surface 11b of 11a is provided with a cavity 16 that constitutes a part of the combustion chamber and into which fuel is directly blown from the fuel injection device. A cooling channel 17 is provided inside the head portion 11.

  The piston 10 includes a piston body 18 in which an entire skirt portion 12 having a boss 13 and a central portion 11a of the head portion 11 are integrally formed, a land portion 14 having a piston ring groove 15, and a peripheral portion 11e of the head portion 11. An integrally formed head annular portion 11c is configured to be joined at the respective joining surfaces 11d and 18d.

  The piston main body 18 includes a bottom surface 16 a of a cavity 16 provided on the top surface 11 b of the central portion 11 a of the head portion 11. Further, the piston pin hole 13a of the boss 13 of the skirt portion 12 is directly opened in a thick portion formed in a pair of opposed portions of the skirt portion 12 without arranging a bronze bush member or the like, and has a predetermined accuracy. It is a through hole.

  On the other hand, the head annular portion 11 c includes a top surface 11 b of the head portion 11 and a lip portion 11 f that protrudes inside the periphery of the cavity 16.

  Further, as shown in FIG. 2, the cooling channel 17 includes an annular path 17 a that continues in an endless annular manner along the head annular portion 11 c, and 2 that penetrates from the bottom of the head portion 11 to the annular path 17 a as shown in FIG. 4. A cooling oil supply path 17c and a discharge path 17d are provided.

  In the first embodiment, the cooling channel 17 includes a plurality of extension passages 17b each having an end hole drilled from the annular passage 17a toward the top surface 11b of the head annular portion 11c. A plurality of the extension paths 17b are arranged at predetermined intervals in the circumferential direction. As shown in FIG. 2, the extension path 17 b is provided at a position corresponding to the fuel 16 b injected into the cavity 16 of the head portion 11, so that the cooling efficiency of a particularly high temperature portion is improved. Yes.

  The joint surfaces 11d and 18d of the head annular portion 11c and the piston main body 18 are inclined so that the end portion on the central portion 11a side is closer to the top surface 11b than the end portion on the peripheral edge portion 11e side of the head portion 11. It is composed of a single tapered surface having a constant gradient.

  The joint surfaces 11d and 18d are formed so as to cross the annular passage 17a, and the joint surfaces 11d and 18d of the head annular portion 11c and the piston main body 18 are opposed to each other to form the annular passage 17a. Thus, annular grooves 11g and 18g are provided.

  Next, a method for manufacturing such a piston 10 will be described with reference to FIG.

  First, the head annular portion 11c and the piston body 18 are produced separately. Here, by producing the head annular portion 11c by forging, sufficient strength such as light weight and tensile strength is ensured. The piston body 18 can be produced by an appropriate method such as forging or casting. In this embodiment, the piston body 18 is produced by forging because it is easy to ensure the strength.

  At that time, it is preferable to manufacture the head annular portion 11c and the piston main body 18 using different materials. The head annular portion 11c is preferably made of a material having higher heat resistance than the piston main body 18, and the piston main body 18 is It is preferable to use a material that can ensure the surface pressure resistance because of the relationship of supporting the piston pin.

Specifically, as the material of the head annular portion 11c, for example, a rapidly cooled aluminum alloy obtained by rapidly solidifying after melting silicon and / or iron-containing aluminum alloy, or further, nickel, chromium, manganese, etc. It may be a powder or metal foil obtained by melting and solidifying the aluminum alloy containing the element. Other metal elements may be contained, and particles and whiskers such as SiC and Al ₂ O ₃ may be added to the above powder and foil as a reinforcing material. Alternatively, a continuous casting rod of aluminum alloy may be used. In that case, particles such as SiC and Al ₂ O ₃ and whiskers may be added as a reinforcing material.

  The material of the piston body 18 may be an aluminum alloy having a different silicon and / or iron content than the material of the head annular portion 11c, or an aluminum alloy having a different content such as copper or magnesium.

  In order to produce the head annular portion 11c by forging using such a material, the quenched powder aluminum alloy is extruded into a round bar shape (step a) and cut into a billet having a size corresponding to the head annular portion 11. (Step b) is performed by forging (step c) and machining (step d) by sandwiching and pressing between a pair of molding dies in the piston axial direction.

  In the forging step (step c), it is preferable to form a tapered surface corresponding to the joint surface 11d on the mold, and further, an annular groove for forming the annular path 17a of the cooling channel 17 on the tapered surface. It is preferable to form 11 g.

  In the step of machining the obtained molded body (step d), the bonding surface 11d is processed to have a single taper surface with a predetermined accuracy. Further, the extension path 17b is formed at a predetermined interval in the circumferential direction from the annular groove 11g toward the top surface 11b.

  Further, in order to produce the piston main body 18 by forging using the material as described above, it is extruded into a round bar shape (step e) and cut into billets having a size corresponding to the piston main body 18 (step f). It is performed by forging (step g) and machining (step h) by sandwiching and pressing between a pair of molding dies in the piston axial direction.

  In the forging step (step g), it is preferable to form a tapered surface corresponding to the joint surface 18d on the mold, and further, an annular groove for forming the annular path 17a of the cooling channel 17 on the tapered surface. It is preferable to form 18 g. Furthermore, the cavity 16 is preferably formed on the top surface 11b side of the head portion 11 by a molding die.

  In the step of machining the obtained molded body (step h), the bonding surface 18d is processed into a single taper surface with a predetermined accuracy so as to be the same as the bonding surface 11d of the head annular portion 11c. Further, a supply path 17c and a discharge path 17d penetrating from the bottom of the head portion 11 to the annular groove 18g are formed.

  After the machining of the head annular portion 11c and the piston main body 18, the head annular portion 11c and the piston main body 18 are joined at the joining surfaces 11d and 18d (step i). This joining method can be performed by various methods such as electron beam welding, laser beam welding, brazing, and friction welding.

  At that time, it is preferable to reduce the melting range. For example, it is also preferable to perform bonding with an electron beam in a small melting range, or bonding without melting the aluminum alloy itself by brazing.

  After joining and integrating, if necessary, the outer shape of the piston 10, the land portion 14 and the piston ring groove 15, and further the machining of the piston pin hole 13a are performed, and if necessary, the piston ring groove 15 and the piston ring groove 15a are machined. An iron-based or nickel-based metal, ceramic, or the like is sprayed on the pin hole 13a or the like (step j).

  Thereafter, final finishing is performed (step k) to complete the manufacture of the piston 10.

  According to the piston 10 of the first embodiment as described above, the joint surfaces 18d and 11d of the piston main body 18 and the head annular portion 11c are formed so as to cross the annular path 17a of the cooling channel 17, so that the piston When the main body 18 and the head annular portion 11c are manufactured, the annular path 17a can be opened in the longitudinal direction on the joint surface, and the annular path 17a can be easily formed as the annular grooves 11g and 18g from the joint surfaces 11d and 18d side. it can. Therefore, it is possible to form the annular grooves 11g and 18g when the head annular portion 11c is forged, and the formation of the annular path 17a of the cooling channel 17 is easy. At the same time, it is not necessary to cast the head annular portion 11c by using a core or burying a pipe for forming a cooling channel, so that the head annular portion 11c itself can be easily manufactured and the strength of the head annular portion 11c itself can be improved. .

  In addition, since the joining surfaces 11d and 18d are formed as a single tapered surface, the entire joining surfaces 11d and 18d have a tolerance as compared with the case where a joining surface is formed by combining a plurality of surfaces such as a horizontal surface and a vertical surface. Can be suppressed, and the joining surfaces 11d and 18d can be easily brought into close contact with each other and can be joined with high accuracy. Further, if the contact is made with high accuracy, joining by electron beam welding or the like can be performed more easily.

  In addition, if the start point and the end point of the joint surface are not changed, the joint surfaces 11d and 18d can be formed with the shortest distance, so that the joining can be performed more easily and accurately, and the volume of the head annular portion 11c can be easily reduced. Therefore, it is easy to forge and the head annular portion 11c can be easily manufactured.

  Further, since the piston main body 18 and the head annular portion 11c are joined by a single taper surface protruding from the central portion 11a side, the thickness of the upper portion of the hole of the boss 13 provided in the piston main body 18 is set to the piston main body 18. Therefore, it is easy to ensure sufficient strength of the boss 13 with respect to the head portion 11. Therefore, the so-called compression height between the top surface 11b of the head portion 11 and the axis of the boss 13 can be kept short.

  Further, in the piston 10, the head annular portion 11 c includes the land portion 14 having the piston ring groove 15 and the lip portion 11 f protruding inside the cavity 16. Sites that require high performance and surface pressure resistance can be concentrated in the head annular portion 11c, and the durability of the piston 10 can be easily improved.

  Furthermore, in this piston 10, since the head annular portion 11c is made of a material having higher heat resistance than the piston main body 18, it is possible to ensure the heat resistance strength of the portion that is likely to become higher in temperature and to improve the durability.

  In addition, since the head annular portion 11c is divided from the piston main body 18 by the joint surfaces 11d and 18d formed of a single tapered surface, the volume of the head annular portion 11c can be reduced, and as a result, the head annular portion 11c. Even if it is made of a special material having a higher heat resistance than the piston body, it is possible to reduce the amount of the material used.

  In particular, since the head annular portion 11c, which requires heat resistance, wear resistance, and surface pressure resistance, is forged from a quenched powder aluminum alloy, the durability can be reliably improved.

  Moreover, in this piston 10, since the piston main body 18 and the head annular portion 11c having the joint surfaces 11d and 18d crossing the annular path 17a are respectively formed by forging, the cooling channel 17 is provided inside the head portion 11. However, it is possible to form the piston 10 with sufficient strength.

  Moreover, the wall thickness can be reduced due to forging, the passage cross-sectional area of the cooling channel can be increased, and the weight of the entire piston can be reduced.

  Further, in the piston 10, the cooling channel 17 includes an extension path 17b drilled from the annular path 17a toward the top surface 11b of the head annular portion 11c. The extension path 17b is provided at a plurality of predetermined intervals in the circumferential direction of the piston. Since it is arranged, it is easier to cool the top surface 11b side of the head portion 11 which is particularly easily heated.

  The above-described first embodiment can be appropriately changed within the scope of the present invention. For example, in the above description, the annular path 17a is formed as a complete endless annular path, but an end portion is provided along the head annular portion 11c. Alternatively, it may be formed as a passage.

Further, in the above, the land portion 14 and all the piston ring grooves 15 are formed in the head annular portion 11c, but it is not particularly limited, and the head annular portion 11c and the piston body 18 are processed after joining, A part of the land part 14 and a part of the piston ring groove 15 may be formed in the piston main body 18. In this case, the top land portion closest to the top surface 11b of the head portion 11 and the pressure ring groove are preferably formed in the head annular portion 11c in order to ensure durability.
[Embodiment 2]

  7 and 8 show a diesel engine piston according to the second embodiment.

  In the piston 20 of the second embodiment, the cooling channel 17 has a configuration different from that of the first embodiment. Here, an annular path 17e as another annular path is formed around the side of the lip portion 11f in the head annular portion 11c on the top surface 11b side from the annular path 17a and is formed side by side in the piston axial direction. It is provided and covered with the ring lid 19, and the annular path 17 a and the annular path 17 e are communicated with each other by a bypass path 17 f. Further, in the piston 20, a cooling oil discharge passage 17 d is provided in an upper portion of the piston pin hole 13 a of the boss 3. Others are the same as in the first embodiment.

  In order to form such an annular passage 17e of the cooling channel 17, for example, when forging the head annular portion 11c with a molding die, a groove corresponding to the annular passage 17e is formed from the top surface 11b side, Next, in a state where the head annular portion 11c is not joined to the piston body 18, the bypass passage 17f including a hole penetrating between the annular groove 11g of the annular passage 17a and the groove corresponding to the annular passage 17e is processed, and thereafter The ring lid body 19 made of the same material as the head annular portion 11c can be formed by electron beam bonding on the top surface 11b side of the groove corresponding to the annular path 17e.

  According to such a piston 20, the same effects as those of the first embodiment can be obtained, and in addition to the annular path 17a traversed by the joint surfaces 11d and 18d, another annular path 17e is provided in the head annular portion 11c. Therefore, the head portion 11 can be cooled by the plurality of annular paths 17a and 17e, and efficient cooling is possible.

In the second embodiment, an example in which the supply path 17c of the cooling channel 17 is connected to the annular path 17a is illustrated. However, it can be changed as appropriate, and the supply path 17c is provided in another annular path 17e. Also good. In that case, since the coolant can be supplied first from the higher temperature side, more efficient cooling is possible.
[Embodiment 3]

  9 and 10 show a piston for a gasoline engine according to the third embodiment.

  The piston 30 of the third embodiment has substantially the same configuration as the piston 10 of the first embodiment except that the extension path 17b is not provided.

Even in the case of a gasoline engine piston as in the third embodiment, the same effects as in the first embodiment can be obtained by applying the present invention.
[Embodiment 4]

  11 to 14 show the head annular portion used in the piston according to the fourth embodiment. The fourth embodiment is a modification of the head annular portion 11c of the first to third embodiments.

  As shown in FIG. 11B, the head annular portion 41c has a land portion 14 having a piston ring groove 15 and an outer peripheral portion 42 having a peripheral edge portion 11e, and an inner peripheral portion 43 having a lip portion 11f. The outer peripheral portion 42 and the inner peripheral portion 43 are integrally formed from different materials. Here, the outer peripheral portion 42 is made of a material 42 a having higher wear resistance and surface pressure resistance than the inner peripheral portion, and the inner peripheral portion 43 is made of a material 43 a having higher heat resistance than the outer peripheral portion 42.

  Specifically, as the material 42a of the outer peripheral portion 42, for example, an alloy used for the head annular portion 11c of the first embodiment or an alloy having an increased SiC content in this alloy can be used. . On the other hand, as the material 43a of the inner peripheral portion 43, an alloy in which the Fe content is increased to the alloy used for the head annular portion 11c of the first embodiment can be used.

  Such a head annular portion 41c can be produced by partially changing steps a to d in FIG. 6, as shown in FIG.

  Here, first, a molding material 40 as shown in FIG. 11A is produced, in which a material 42a constituting the outer peripheral portion 42 and a material 43a constituting the inner peripheral portion 43 are previously molded into a double ring structure inside and outside. .

  The molding material 40 is not particularly limited. For example, different materials as described above, preferably, materials 42a and 43a made of two types of rapidly solidified alloys are laminated (steps). p) It can be formed into a hollow double tube shape by double tube extrusion, or formed into a hollow double tube shape by plasma discharge sintering or other sintering (step q).

  In order to form by double tube extrusion, for example, as shown in FIG. 11, an inner peripheral portion 43 is formed inside a molded body formed into a container shape by casting, forging or sintering from a material 42a of the outer peripheral portion 42. The material 43a is filled with powder (a), and is passed through a mold 44 that can be extruded into a hollow shape to form a hollow cylinder corresponding to the outer diameter of the head annular portion 11c (b). The forming material 40 can be obtained by cutting (c) with a length corresponding to the head annular portion 11c.

  Further, in order to produce the molding material 40 by plasma sintering or other sintering, for example, as shown in FIG. 13, a container 45 having a core disposed at the center is partitioned by a cylindrical body 46, and the inside of the container 45 is The inside and outside of the cylindrical body 46 are filled with the respective powder materials 42a and 43a, and after the cylindrical body 46 is extracted, sintered, and then forged under strong pressure, the outer diameter of the head annular portion 11c and A molding material 40 having a dimension corresponding to the length can be obtained.

  Next, using such a molding material 40, forging is performed by strongly pressing the upper and lower molds in the same manner as in the first embodiment (step c), and the head annular portion 11c having the annular groove 11g is formed. Mold to the corresponding shape.

  Then, by machining, as shown by the phantom line in FIG. 11B, a joint surface 11d formed of a single tapered surface is formed with a predetermined accuracy (step d) to form the head annular portion 41c. it can.

  Thereafter, the head annular portion 41c is joined to the piston body 18 (step i), the top surface 11b, the land portion 14 and the piston ring groove 15 are machined or thermally sprayed with metal or ceramics as required (step j). When the final finishing process is performed (step k), the head annular portion 11c as shown by the phantom line in FIG. 11B can be finished with a predetermined accuracy in an integrated state with the piston body 18. Pistons 10, 20, and 30 can be obtained.

  In the pistons 10, 20, and 30 using the head annular portion 41c, the outer peripheral portion 42 including the land portion 14 is made of a material having higher wear resistance and surface pressure resistance than the inner peripheral portion 43, and the lip portion 11f. Since the inner peripheral portion 43 having the heat resistance is made of a material having higher heat resistance than the outer peripheral portion 42, an optimum material corresponding to different properties required in each part of the head annular portion 41c can be used, and the temperature becomes higher. It is possible to ensure the heat resistance strength of the easy part and the wear resistance of the part where wear is likely to occur, and it is possible to further improve the durability of the head annular portion 41c.

  In the fourth embodiment, the head annular portion 41c using two different types of materials has been described. However, the head annular portion 41c can be similarly manufactured using three or more types of different materials.

  On the other hand, the manufacturing process can be variously changed. For example, as shown in FIG. 14B, three or more types of aluminum powder may be laminated in the step p. Further, before the aluminum powder is sintered, a wear ring for the piston ring groove 15 may be installed and sintered (step r). In that case, after joining the head annular portion 41c and the piston main body 18 (step i), it is not necessary to spray metal or ceramics. Furthermore, it is also possible to sufficiently machine each part before joining (step i) and to perform finishing (step k) without performing machining after joining (step i).

It is a side view of the piston for diesel engines which concerns on Embodiment 1 of this invention. It is a top view of the piston of the first embodiment. It is AA sectional drawing of the same Embodiment 1. FIG. It is BB sectional drawing of the same Embodiment 1. It is a bottom view of the piston of the first embodiment. It is a figure which shows the manufacturing process of the piston of the same Embodiment 1. FIG. FIG. 5 is a cross-sectional view showing a piston for a diesel engine according to Embodiment 2 of the present invention and corresponding to the AA cross section of FIG. 2. It is sectional drawing equivalent to the BB cross section of FIG. 2 which shows the piston of the same Embodiment 2. FIG. FIG. 5 is a cross-sectional view showing a gasoline engine piston according to Embodiment 3 of the present invention and corresponding to the AA cross section of FIG. 2. It is sectional drawing equivalent to the BB cross section of FIG. 2 which shows the piston of the same Embodiment 3. It is sectional drawing which shows the head annular part of the piston which concerns on Embodiment 4 of this invention, (a) is the raw material before shaping | molding, (b) shows the state after shaping | molding and a process. It is a figure which shows the process of producing the molding raw material of FIG. 11 by double extrusion. It is sectional drawing which shows the container for producing the shaping | molding raw material of FIG. 11 by sintering. (A) is a figure which shows the manufacturing process of the head annular part of Embodiment 4, and a piston using the same, (b) is a figure which shows the modification of a manufacturing process.

Explanation of symbols

10, 20, 30 Piston 11 Head portion 11a Central portion 11b Top surface 11c, 41c Head annular portion 11d, 18d Joint surface 11e Peripheral portion 11f Lip portion 12 Skirt portion 13 Bin boss 14 Land portion 15 Piston ring groove 16 Cavity 17 Cooling channel 17a , 17e annular path 17b extension path 18 piston body 42 outer peripheral part 43 inner peripheral part

Claims (8)

In the piston for an internal combustion engine provided with an annular passage of a cooling channel inside the head part,
Forged with a piston body integrally provided with a skirt portion having a boss formed with a piston pin hole and a central portion of the head portion, a land portion having a piston ring groove, and a peripheral portion of the head portion. The head annular portion is joined at the joining surface,
The joint surface is formed of a single tapered surface that traverses the annular channel of the cooling channel and is inclined so that the end on the center side is closer to the top surface than the end on the peripheral edge side. A piston for an internal combustion engine. The head portion has a cavity on the top surface;
2. The piston for an internal combustion engine according to claim 1, wherein the head annular portion includes a lip portion protruding inward of the cavity.   The head annular portion includes an outer peripheral portion having the land portion and an inner peripheral portion having the lip portion, and the outer peripheral portion and the inner peripheral portion are made of different materials, and the outer peripheral portion is the inner peripheral portion. The piston for an internal combustion engine according to claim 2, characterized in that the wear resistance is higher than that of the portion, and the inner peripheral portion has higher heat resistance than the outer peripheral portion.   The piston for an internal combustion engine according to any one of claims 1 to 3, wherein the head annular portion is made of a material having higher heat resistance than the piston main body.   The piston for an internal combustion engine according to any one of claims 1 to 4, wherein the head annular portion is forged from a rapidly solidified alloy.   The piston for an internal combustion engine according to any one of claims 1 to 5, wherein the piston body is forged.   The cooling channel includes an extension path including an end hole drilled from the annular path toward the top surface of the head annular portion, and a plurality of the extension paths are arranged at predetermined intervals in the circumferential direction of the piston. The piston for an internal combustion engine according to any one of claims 1 to 6, wherein the piston is used. The cooling channel includes, in addition to the annular path traversed by the joining surface, another annular path formed in the head annular portion side by side in the piston axial direction, and the two annular paths communicate with each other by a bypass path. The piston for an internal combustion engine according to any one of claims 1 to 7.

Images