JPH0542738U - Connecting - Google Patents

Abstract

(57) [Summary] [Purpose] To increase the strength and weight of sintered connecting rods. [Structure] A connecting rod with a three-layer structure of an intermediate layer made of a sintered material and both end layers made of steel plates, and the column section having an H-shaped cross section. This connecting rod having a three-layer structure can be manufactured by sandwiching a sintered body, which is an intermediate layer, between two steel plate members, which are both end layers, and joining them. Since the sintered body is reinforced by the steel plate, the thickness of the sintered body is reduced to reduce the weight, and the outer diameter of the small end portion of the steel plate member and the width of the column portion have the same size to eliminate stress concentration portions.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a connecting rod, which is a component for a reciprocating engine, and specifically to a lightweight and high-strength non-forged connecting rod.

[0002]

[Prior Art]

 It is well known that the connecting rod that connects the piston and the crankshaft is composed of a small end having a piston pin hole, a large end having a crankshaft hole, and a column portion between both ends. .. In order to manufacture a connecting rod with such a complicated shape, the sintering method is more advantageous than the general hot forging method in terms of productivity and manufacturing cost.

The connecting rod is a component that is required to have a predetermined rigidity and fatigue strength and be lightweight. Therefore, a conrod having a column-shaped cross-section with an H shape to reduce weight has been developed. Strictly speaking, this H-shape is the cross-sectional shape when the connecting rod is positioned so that the axes of both the large-end hole and the small-end hole are on the same horizontal plane, and the column part is cut along the plane perpendicular to the longitudinal direction. The column portion having such a shape is simply referred to as a column portion having an H-shaped cross section in this specification.

Since a connecting rod having a column portion having an H-shaped cross section has a concave groove that is an undercut in the column portion, it is not possible to manufacture all such connecting rods at once by a sintering method due to restrictions on the mold structure. Therefore, when a connecting rod having a column portion having an H-shaped cross section is manufactured by a sintering method, first, a connecting rod is divided into two parts by a sintering method, as disclosed in Japanese Patent Laid-Open No. 2-129305. Then, they are joined and manufactured.

A sleeve-shaped bearing metal is attached to each hole at both ends of the connecting rod. However, if the large end portion is largely deformed under load, sludge is generated on the metal rear surface on the large end side, and the metal rear surface is Fretting (fine wear) of the connecting rod, fretting of the mating surface of the connecting rod with the metal, etc., may cause seizure, damage to the large end, and engine vibration noise, so it is particularly high at the large end of the connecting rod. Needs rigidity. Since the rigidity is determined by the product of Young's modulus and the moment of inertia of area, in order to obtain the same rigidity as the ingot material (E ≈ 21000 kg / mm ² ) with a sintered material having a Young's modulus E as low as 16000 kg / mm ² , It is necessary to increase the second moment of area. The conventional method for increasing the second moment of area is to enlarge the large end, that is, to increase the wall thickness a of the large end 61 [see Figs. 3 (a) and (c)]. If there is a limit to avoiding interference with the cylinder block, it is a method of providing a surplus portion at another appropriate portion.

[0006]

[Problems to be solved by the device]

 However, since the weight is increased by enlarging the large end in such a manner, there is a problem in that the weight of the fired connecting rod is still insufficient even if the column portion has an H-shaped cross section.

There are other reasons that make it difficult to sufficiently reduce the weight of the sintered H-type connecting rod, which cannot reduce the column width d (width dimension of the column portion) shown in FIG. 3A. Here it is. When the column width d is made smaller than the outer diameter c of the small end portion by force, an R-shaped concave portion is formed near the boundary between the column portion 62 and the small end portion 63. In the H-shaped connecting rod, since the cross-sectional area of this recessed portion is smaller than that of the I-shaped connecting rod (by casting), the stress concentration is large, and this stress concentration is the fatigue strength near the boundary between the column portion 62 and the small end portion 63. Will weaken.

In order to eliminate this stress concentration, it is desirable to make the outer diameter c of the small end portion and the column width d as equal as possible. That is, it is ideal that the thickness b (see FIG. 3 (b)) of both side portions of the H-shaped column portion 62 is reduced in order to reduce the cross-sectional area after d≈c. However, even if an attempt is made to reduce the thickness b from the current thickness of at least 3 mm to reduce the weight, molding cracks or uneven density may occur in the thinned portion during molding. The problem is that the wall thickness b cannot be reduced.

The present invention has been made for the purpose of solving the above problems, and the problem to be solved is that it can be manufactured without forging, and has rigidity and fatigue strength comparable to those of forged connecting rods. It is an object of the present invention to provide a connecting rod which has a further reduced weight compared to the conventional sintered connecting rod.

[0010]

[Means for Solving the Problems]

 The connecting rod having a column portion having an H-shaped cross-section according to the present invention that can achieve the above object is integrated by sandwiching an intermediate layer made of a sintered material between two connecting rod-shaped steel plate members having holes at both ends. It has a three-layer structure.

This connecting rod having a three-layer structure can be manufactured by sandwiching a sintered body, which is an intermediate layer, between two steel plate members, which are both end layers, and joining them. At that time, a steel plate member having a column-shaped “one” shape, a sintered body having a column-shaped “I” shape, and a steel plate member having a column-shaped “one” shape were sequentially stacked and joined to each other, thereby manufacturing a controller. The cross section of the column portion of the cord has an H shape.

The material and manufacturing method of the sintered body may be the same as those of the conventional sintered connecting rod. The term "sintered body" as used herein includes, of course, those that are obtained by sintering, but also those that are lightly forged after sintering. The steel plate member may be cast, but it is convenient to manufacture it by simply punching it from the steel plate. It is preferable to select a material having a high mechanical strength, especially a material having a high Young's modulus, for example, carbon steel for machine structural use or chrome steel is sufficient. The thickness of the steel plate member depends on the material and strength required for the connecting rod, but may be approximately 2 to 5 mm. Various welding methods can be applied to join the sintered body and the steel plate member, but the brazing method is the simplest method.

[0013]

[Operation] The steel plate is relatively stronger than the sintered material. Therefore, when the connecting rod is made to have a predetermined strength, if a steel plate is used, it becomes possible to omit the sintered material in excess of the weight used, for example, to reduce the wall thickness of the large end portion or reduce the column width. Therefore, the weight of the conrod is reduced. By using a steel plate made of a material having mechanical properties that are tougher than forged steel, the three-layer structure connecting rod can have rigidity and fatigue strength comparable to those of a forged connecting rod. Also, when the column width of the sintered connecting rod is made narrower than the outer diameter of the small end, the stress concentration that occurs near the boundary between the column portion and the small end is caused by equalizing the column width and the outer diameter of the small end in the steel plate member. It won't happen.

[0014]

【Example】

The connecting rod of the present embodiment has a three-layer structure in which the steel plate member 1, the sintered body 2 and the steel plate member 3 shown in FIGS. 1 and 2 are joined. Since the sintered body 2 constitutes the intermediate layer, and the column width d ₂ of the sintered body 2 is considerably smaller than the column widths d ₁ and d ₃ of the steel sheet members 1 and 3 of both end layers, The cross section of the entire three-layer structure column section taken along the plane perpendicular to the longitudinal direction is H-shaped. This connecting rod having a three-layer structure is manufactured by sandwiching and joining the sintered body 2 between the steel plate members 1 and 3.

The method of manufacturing the connecting rod of this example is as follows: (1) Manufacture of a sintered body 2% by weight of iron powder (Fe-0.6P) containing 0.6% by weight of phosphorus was prepared. Copper powder, 0. 6% by weight of graphite and 0.8% by weight of zinc stearate as a lubricant were mixed, and the mixed powder was filled in a compression mold for forming a connecting rod, and the average of about 6 ton / cm ² was obtained. Molding is carried out under surface pressure to produce a powder compact having a density of approximately 7.0 g / cm ^{3 in} each part. The powder compact thus obtained is fired in an N ₂ atmosphere at 1250 ° C. for 60 minutes to obtain a sintered compact which will be an intermediate layer of the connecting rod. (2) Manufacture of steel plate member Using a general punching die equipped with a punch and a die, a steel plate having a thickness of 2 mm and made of carbon steel (S45C) is punched out to obtain a steel plate having the same shape as the side surface of the connecting rod. Steel plate members used as both end layers of the. As shown in FIG. 2, the column widths d ₁ and d _{3 of the} steel plate members ₁ and ₃ and the small end outer diameters c ₁ and c ₃ are the same. (3) Joining of Sintered Body and Steel Plate Member When sandwiching the sintered body 2 between the two steel sheet members 1 and 3, a copper plate with a thickness of 0.2 mm cut into a joint surface shape is used for each steel sheet member 1 and 3. 3 and the sintered body 2, and heated in a vacuum furnace at 1100 ° C. for about 5 minutes to bond them.

As can be seen from FIG. 2, in the connecting rod of this embodiment, the collum widths d ₁ and d ₃ and the small outer diameters c ₁ and c ₃ of the steel plate members 1 and ₃ are the same. Since there is no concave shape of the R curved surface near the boundary between the column part and the small end, the stress concentration that occurs near the boundary between the column part and the small end of the conventional connecting rod does not occur. While satisfying the strength criteria required for connecting rods, it is even lighter than conventional sintered connecting rods.

[0017]

[Effect of the device]

 According to the present invention, since the connecting rod has a three-layer structure of a steel plate layer-sintered material layer-steel plate layer, steel plates having a high Young's modulus can be combined to improve rigidity and fatigue strength, and the thickness of the sintered body can be increased. Can be made thinner and the connecting rod can be made lighter. In addition, since the wall thickness of the large end can be reduced in this way, interference between the connecting rod and the cylinder block is less likely to occur, and the degree of freedom in engine design can be increased. Moreover, since the shape of the sintered body is simple, the structure of the molding die is simple and the variation in density is small. Also, the mold cost can be reduced.

Further, in the conventional sintered connecting rod by two-piece molding / joining, it was not possible to omit the extra thickness 7 (see FIG. 3) in the vicinity of the small end due to restrictions on molding, but the present proposal Since the connecting rod can be manufactured by a molding method that does not require extra thickness, the weight can be reduced in this respect as well. In particular, the present invention is significant in that it opens the way for manufacturing lightweight and high-strength connecting rods without forging.

[Brief description of drawings]

FIG. 1 is an exploded front view of a connecting rod according to an embodiment of the present invention.

FIG. 2 is a side view of the same.

FIG. 3 is a view showing a conventional sintered connecting rod, (a) is a side view showing a part in section, (b) is a front view, and (c) is a front view.
It is an AA line cutting end view of (a).

[Explanation of symbols]

1 steel plate member 2 sintered body 3 steel plate member 61 large end portion 62 column portion 63 small end portion c, c ₁ , c ₂ , c ₃ small end outer diameter d, d ₁ , d ₂ , d ₃ column width (column Width of part)

Claims (1)

[Scope of utility model registration request] 1. A connecting rod-shaped 2 having holes at both ends.
A connecting rod having a column portion with an H-shaped cross section, characterized by having a three-layer structure in which an intermediate layer made of a sintered material is sandwiched between a plurality of steel plate members and integrated.