JPH0625537U - Piston for internal combustion engine - Google Patents

Abstract

(57) [Summary] [Object] To provide a welded assembly type piston for an internal combustion engine capable of preventing damage to a cooling passage and ensuring a cooling effect. [Structure] A first divisional body 1 and a second divisional body 2 are welded at respective divisional surface portions to form a crown portion 4 of a piston body 3, and an annular cooling passage 5 is formed in the crown portion 4. In a piston for an internal combustion engine, the divided surface portions of the first divided body 1 and the second divided body 2 are composed of two continuous crossing divided surface portions 6 and 7 which are welded and joined by an electron beam. One of the divided surface portions 6 is arranged outside the cooling passage 5, and the other divided surface portion 7 is arranged so as to intersect with the cooling passage 5.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a welded assembly type piston for an internal combustion engine used in a diesel engine or the like.

[0002]

[Prior art]

 In a diesel engine, in order to improve the cooling function of the crown part of the piston with the increase in output and longer stroke, when providing an annular cooling passage in the crown part, install it integrally with the piston by casting etc. Therefore, it is necessary to weld the first divided body and the second divided body at the respective divided surface portions to form the crown portion of the piston body and to form the annular cooling passage in the crown portion. ing . The welding-assembled type internal combustion engine pistons manufactured in this manner include those disclosed in, for example, Japanese Patent Publication No. 61-169646 and Japanese Utility Model Publication No. 1-78249.

In the piston for internal combustion engine disclosed in Japanese Patent Laid-Open No. 61-169646, as shown in FIG. 3, the first divided body 20 and the second divided body 21 are divided into two divided surface portions 23 reaching the cooling passage 22. , 24, and the respective divided surface portions 23, 24 are joined from the inner end portions 23a, 24a facing the cooling passage 22 by first tungsten inert (TIG) welding and then by layer welding by metal argon gas (MAG) welding. .

Further, in the internal combustion engine piston described in Japanese Utility Model Laid-Open No. 1-78249, as shown in FIG. 4, the first divided body 26 and the second divided body 27 have cooling passages at inner end portions 28a and 29a. There are two division surface portions 28 and 29 up to 30. Each division surface portion 28, 29 does not weld the inner end portions 28a, 29a, but only the portions 28b, 29b outside the inner end portion are welded and joined by electron beam. is doing.

[0005]

However, in the piston for the internal combustion engine shown in FIG. 3, flash due to the welding material protruding from the inner end portions 23a, 24a of the two split surface portions 23, 24 into the cooling passage 22 is generated. There is a risk that the cooling passage 22 may be deformed, the cooling oil may not flow smoothly, and a sufficient cooling effect may not be obtained.

Further, in the piston for internal combustion engine shown in FIG. 4, since the inner end portions 28a and 29a of the split surface portions 28 and 29 are not welded, when the engine output is increased, the unwelded portions 28a and 29a thereof are not welded. There is a possibility that cracks may occur in the welded portions formed at the welded portions 28b and 29b starting from, and the cooling passage 30 may be damaged.

The present invention has been made to solve the above-mentioned conventional problem, and provides a piston for an internal combustion engine of a welded assembly type capable of preventing damage to a cooling passage and ensuring a cooling effect. With the goal.

[0008]

[Means for Solving the Problems]

 In order to achieve the above object, a piston for an internal combustion engine according to the present invention forms a crown portion of a piston body by welding a first division body and a second division body at respective division surface portions, and In an internal combustion engine piston in which an annular cooling passage is formed in the crown portion, the divided surface portions of the first divided body and the second divided body are formed by two intersecting continuous divided surface portions which are welded and joined by an electron beam. One of the two divided surface portions is arranged outside the cooling passage, and the other divided surface portion is arranged so as to intersect with the cooling passage.

[0009]

[Action]

 According to the above configuration, one split surface portion arranged outside the cooling passage and the other split surface portion that intersects with the cooling passage are welded by the electron beam so as to cross each other continuously, and there is no unwelded portion. , Even if the engine power is increased, the cooling passage will not be damaged. The other split surface is welded across the cooling passage, but since it is electron beam welding, the projections (welding spatter) generated on the inner surface of the cooling passage are extremely small, so the cooling effect is impeded. I can't.

[0010]

【Example】

 An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 is an enlarged view of an essential part showing an example of a crown portion of a piston body.

In the figure, 1 is a first divided body, 2 is a second divided body, and the crown portion 4 of the piston body 3 is formed by the first divided body 1 and the second divided body 2, and An annular cooling passage 5 is formed in the crown portion 4. The cooling passage 5 has a substantially elliptical cross section along the axial direction of the piston body 3.

The first divided body 1 and the second divided body 2 have two divided surface portions 6 and 7 which are welded and joined by an electron beam and which are continuous at an angle of 90 °. One of the divided surface portions 6 and 7 is arranged outside the cooling passage 5 and extends cylindrically in the axial direction of the piston body 3. The other split surface portion 7 is arranged so as to intersect with one end portion of the cooling passage 5 and extends in the radial direction of the piston body 1, and is divided into two parts, an inner portion 7 a and an outer portion 7 b, via the cooling passage 5. It is divided into two.

In the above structure, the split surface portions 6 and 7 are welded by an electron beam from the piston crown surface side and the piston side surface toward the intersection portion A, respectively. Are continuous. For this reason, the crown portion 4 of the piston body 3 can be firmly assembled without an unwelded portion, and as a result, even if the engine output is increased, the cooling passage 5 in the crown portion 4 is not damaged.

Further, the split surface portion 7 is welded to intersect one end of the cooling passage 5, but since it is electron beam welding, a protrusion (welding spatter) generated on the inner surface of the cooling passage 5 is extremely difficult. Small. Therefore, the cooling oil smoothly flows in the cooling passage 5, and a sufficient cooling effect can be obtained.

In this embodiment, one split surface portion 6 of the first split body 1 and the second split body 2 that extends in the axial direction of the piston body 3 is arranged outside the cooling passage 5, and the piston body 1 The other divided surface portion 7 extending in the radial direction was arranged so as to intersect with the cooling passage 5, but as shown in FIG. 2, the piston body 3 of the first divided body 11 and the second divided body 12 is Even if one split surface portion 16 that extends in the axial direction intersects the cooling passage 5 and the other split surface portion 17 that extends in the radial direction of the piston body 1 is disposed outside the cooling passage 5, good. In this case, one split surface portion 17 arranged outside the cooling passage 5 and the other split surface portion 16 that intersects the cooling passage 5 are welded by an electron beam from the intersection B side, and both split surface portions 16, 17 are formed. The welds are continuous at the intersection B of the above.

Further, although the two divided surface portions 6, 7; 16 and 17 intersect and continue at 90 °, it goes without saying that the intersecting angle is not limited to 90 °.

[0018]

[Effect of device]

 As described above, according to the present invention, the respective divided surface portions of the first divided body and the second divided body which form the crown portion of the piston body and form the annular cooling passage in the crown portion are welded and joined by the electron beam. It is composed of two divided surface sections that are continuous in succession. One of the two divided surface sections is arranged outside the cooling passage, and the other divided surface section is arranged so as to intersect the cooling passage. Since the crown part of the piston body can be firmly assembled without welding parts, the cooling passage will not be damaged even if the engine output is increased. Also, although the other split surface is welded across the cooling passage, the projections (welding spatter) generated on the inner surface of the cooling passage are very small because of electron beam welding, so the inside of the cooling passage is Cooling oil flows smoothly, and sufficient cooling effect can be secured.

[Brief description of drawings]

FIG. 1 is an enlarged view of a main part showing an embodiment of the present invention.

FIG. 2 is an enlarged view of a main part showing another embodiment of the present invention.

FIG. 3 is an enlarged view of a main part showing one conventional example.

FIG. 4 is an enlarged view of a main part showing another conventional example.

[Explanation of symbols]

 1, 11 1st division body 2, 12 2nd division body 3 Piston body 4 Crown part 5 Cooling passage 6, 7, 16, 17 Division surface part A, B Intersection part

Claims (1)

[Scope of utility model registration request] 1. A piston for an internal combustion engine, wherein a first divided body and a second divided body are welded at respective divided surface portions to form a crown portion of a piston body, and an annular cooling passage is formed in the crown portion. , The divided surface portions of the first divided body and the second divided body are constituted by two intersecting continuous divided surface portions that are welded and joined by an electron beam, and one of the divided surface portions is outside the cooling passage. The piston for an internal combustion engine, wherein the other split surface portion is disposed so as to intersect with the cooling passage.