JPH0526223A - Connecting rod for internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent fretting abrasion in the mating surface of a big end and a rod part of a three-split connecting rod. CONSTITUTION:A theft part 4 is provided in mating surfaces 11a, 12a of a rod part 12 and a big end 11 to form a non-contact part 5 within a range at 20-70% of a full width. Bolt fastening force is thereby concentrated to the contact part of the mating surfaces to fasten the bolt strongly under the condition that a high surface pressure is maintained. Furthermore, since a part near the central part is maintained non-contact, fretting abrasion at the mating surfaces is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a three-part connecting rod used in a relatively large internal combustion engine.

[0002]

2. Description of the Related Art A three-divided connecting rod is divided into a central portion of a large end to which a crankshaft is connected and a portion where a rod portion above the large end is continuous. It has a structure that is integrated by bolting. A compressive force associated with bolt tightening is applied to this mating surface. In addition to this, a compressive force due to generation of in-cylinder pressure and a tensile force due to inertial force alternately act during engine operation. Especially in the mating surface between the large end and the rod, the combined force varies greatly,
Moreover, because of the structure, it is difficult to apply a sufficient tightening force by the bolt to the central portion, so that when the inertial force acts, the surface pressure becomes almost zero and the so-called open state occurs. This phenomenon is remarkable in an engine having a high rotation speed and an engine having a long stroke, and since minute friction and collision are repeated between the mating surfaces, fretting wear is likely to occur in the central part of the mating surfaces.

Countermeasures against this fretting wear are taken, for example, by increasing the strength of the housing at the large end. For example, in Japanese Utility Model Publication No. 47-1132, the mating surface between the large end and the rod is a conical surface. It has been proposed to improve the rigidity of the upper housing at the large end. But,
Although this proposal is effective in preventing fatigue damage to the housing, it is not very effective in fretting wear and has not solved the problem.

[0004]

In view of this point, the present invention has been made to prevent the above-mentioned fretting wear on the mating surface between the large end portion and the rod portion.

[0005]

In order to achieve the above object, in the first aspect of the invention, in a three-divided connecting rod, the central portion of at least one of the mating surfaces of the rod portion and the large end portion is dull. By forming the portion, a non-contact portion where the mating surfaces do not contact each other is formed within a range of 20% to 70% with respect to the entire width in the direction perpendicular to the crankshaft. Further, the connecting rod is provided with a lubricating oil passage extending from the large end portion to the rod portion, and the opening at the mating surface of the lubricating oil passage is provided at a portion other than the recessed portion. In this case, it is desirable to provide the recessed portion on the mating surface of the upper housing at the large end.

According to the second aspect of the present invention, a protrusion is provided at the center of the mating surface above the large end, and a recess is provided on the mating surface of the rod portion so that the protrusion fits without a gap. A non-contact portion is formed between the end surface and the bottom surface of the recess. Further, according to the third aspect of the invention, by forming the recessed portions on both outer edges of at least one of the mating surfaces of the rod portion and the large end portion, the total width is 10% to 50% with respect to the entire width in the direction perpendicular to the crankshaft. In the range of%, non-contact portions where the mating surfaces do not contact each other are formed in the bolted portion.

[0007]

According to the first aspect of the present invention, the tightening force of the bolt can be concentrated on the contact portion of the mating surface to maintain a high surface pressure for firm tightening, and the fretting wear of the mating surface is likely to occur. Since the portions in the vicinity are not brought into contact with each other, fretting wear due to insufficient tightening is prevented. By providing the opening of the lubricating oil passage in a portion other than the recessed portion, that is, a portion that is firmly tightened while maintaining a high surface pressure, a sealing member such as an O-ring for preventing leakage of lubricating oil from the mating surface is provided. It becomes unnecessary. Also, since the mating surface side of the rod portion is generally thinner than the large end portion, stress concentration is likely to occur if a slim portion is provided, but the slim portion should be provided on the mating surface of the upper housing at the large end portion. This prevents stress concentration.

According to the second aspect of the invention, the rigidity of the upper housing is increased by the projection of the large end portion, the deformation of the housing during operation is reduced, and the bearing wear is reduced. Also, since the end face of the protrusion does not contact the rod part, fretting wear near the center, which tends to cause insufficient tightening, is prevented, and the tightening force of the bolt is applied to the fitting of the protrusion and the recess for a stronger connection. Becomes According to the third invention, since the tightening force of the bolt is concentrated on the contact portion of the mating surfaces, the surface pressure near the center is also kept high, the mouth opening due to the inertial force is prevented, and the fretting caused by insufficient tightening is prevented. Wear is prevented.

[0009]

[First Embodiment of the Invention] The illustrated embodiment will be described below. 1 and 2 show an embodiment of the first invention, in which reference numeral 1 is a connecting rod composed of a large end portion 11, a rod portion 12 and a small end portion 13. The large end portion 11 is divided at the central portion, and the upper housing 11-1 and the lower housing 11-2 are integrated by tightening the bolt 2, and the upper housing 11-1 and the rod portion 12 are connected to each other by the bolt 3. It is integrated by tightening. The small end portion 13 is formed integrally with the rod portion 12.

Reference numeral 4 denotes a recessed portion, which is the upper housing 1.
Although it is formed on at least one of the mating surface 11a on the upper surface of 1-1 and the mating surface 12a on the lower end of the rod portion 12, the example shown in the drawing is formed on the mating surface 11a. The recessed portion 4 is formed by cutting the central portion of the mating surface 11a in the direction of the crankshaft to a depth of, for example, about 50 μm to 1 mm. As shown in FIG. 20% to 70 with respect to the total width B in the direction perpendicular to
%, So that the mating surfaces 11a, 12
A non-contact portion 5 that does not contact each other is formed between a. Reference numerals 6a and 6b denote lubricating oil passages for supplying lubricating oil from the large end portion 11 to the small end portion 13. The lubricating oil passages are formed in the large end portion 11 and the rod portion 12, respectively. Since they are open to the unopened portion and communicate with each other, a sealing member such as an O-ring is unnecessary. 6c is a plug, 3a and 3b are bolt holes, 7 is a knock pin, and 7a is a knock pin hole.

FIG. 3 shows the state of the surface pressure between the mating surfaces 11a and 12a. (A) shows the case where the formation area A of the recessed portion 4 is less than 20% of the total width B, (b). Shows the case of 70%, and (c) shows the case of 40%. The horizontal axis shows the position from the center of the mating surface to the outer edge in%. C in the figure is the bolt position, and the bolt tightening force is highest at the position C as shown by the solid line, and becomes smaller toward the outside and inside. When the in-cylinder pressure action and the inertial force action also change in almost the same tendency as shown by the chain line and the broken line, respectively, but the formation range A of the recessed portion 4 is 20% or less of the total width B. Is almost zero in the center when the inertial force acts near 20%, and when the forming range A is 70% or more of the total width B, the surface pressures increase with the in-cylinder pressure. The surface pressure of No. 1 suddenly increases around 70%.

As described above, when the recessed portion 4 is small, the surface pressure in the vicinity of the center becomes low, and when the inertial force acts, the mouth is easily opened and fretting wear occurs. On the other hand, when the recessed portion 4 is large, the surface pressure during the action of the in-cylinder pressure becomes excessive near the boundary of the recessed portion 4, which causes damage and wear, but the formation range of the recessed portion 4 is appropriate. If so, an appropriate surface pressure is maintained as shown in (c). FIG. 4 illustrates the relationship between the size of the recessed portion 4 and the amounts of fretting wear and damage wear, and the solid line represents the fretting wear amount and the broken line represents the damage wear amount. That is, the fretting wear tends to start from about 20% in the formation range of the recessed portion 4 and rapidly increase below that, and the damage wear tends to start from about 70% and rapidly increase above that. . Therefore, it is considered appropriate that the formation range of the recessed portion 4 is about 20% to 70%, and by providing the recessed portion 4 in this range, both fretting wear and damage wear can be eliminated.

FIGS. 5 and 6 show another embodiment, in which the recessed portion 4 is formed on the mating surface 12a at the lower end of the rod portion 12,
The lubricating oil passages 6a and 6b are opened in the portion where the recessed portion 4 is formed so as to communicate with each other. In this case, it is necessary to prevent the lubricating oil from leaking from the slime portion 4,
Although the O-ring 8a is provided by providing the O-ring groove 8a on the mating surface 11a, such a structure facilitates the processing of the lubricating oil passage 6b. Note that the recessed portion 4 is the mating surface 11 a of the large end portion 11 and the mating surface 1 of the rod portion 12.
Although it may be provided on any of 2a, if the recessed portion 4 is formed on the mating surface 12a, the thickness of the portion indicated by D in the figure becomes thin, which may cause stress concentration. For this reason, depending on the shape of the rod portion 12, the recessed portion 4 may be formed into the large end portion 11
It may be more desirable to provide it on the mating surface 11a.

[0014]

[Embodiment of the Second Invention] FIGS. 7 to 9 show an embodiment of the second invention. The same parts as those in the above-described embodiment are designated by the same reference numerals, and different points will be mainly described. In the figure, 21 is a protrusion provided in the central portion of the mating surface 11a of the large end 11, 22 is a recess provided in the mating surface 12a of the rod portion 12 corresponding to the protrusion 21,
The protruding portion 21 and the recessed portion 22 are formed to have a size of about H6 or H7 so that they can be fitted tightly with no space. The height of the protrusion 21 and the depth of the recess 22 are selected so that the end surface 21a of the protrusion 21 does not contact the bottom surface 22a of the recess 22 and the non-contact portions 5 do not contact each other between them. The height h of 21 is 10% of the thickness H of the lower end of the rod portion 12.
To 60%. The protrusion 21 and the recess 22
The formation range A is selected to be 20% to 70% of the total width B.

This embodiment has the above-described structure, and the rigidity of the upper housing 11-1 is increased by the protruding portion 21, so that the deformation of the housing during operation is reduced and the contact of the bearing is made uniform. Bearing wear at the portion 11 is reduced. Further, since the end surface 21a of the protruding portion 21 is not brought into contact with the bottom surface 22a of the recessed portion 22, fretting wear in the vicinity of the center where tightening by the bolt 3 is likely to be insufficient is prevented. Furthermore, since the projection 21 and the recess 22 are fitted together without a gap, a positioning function is obtained and a knock pin is not required, and relative sliding of the mating surfaces is prevented at the fitting portion, and a strong connection is achieved by the tightening force of the bolt 3. It will be possible. Although the protrusion 21 and the recess 22 are square in FIGS. 7 and 8, they may have a circular cross section as shown in FIG. By doing so, it becomes possible to process the lathe easily and efficiently.

[0016]

[Embodiment of the Third Invention] Next, an embodiment of the third invention will be described. In FIGS. 10 and 11, reference numeral 14 denotes a recessed portion, which is a mating surface 11a on the upper surface of the upper housing 11-1.
Although it is formed on at least one of the mating surfaces 12a at the lower end of the rod portion 12, the drawing shows an example in which it is formed on the mating surface 12a. The recessed portion 14 is formed by cutting the outer surface of the mating surface 12a where the bolt holes 3b are provided at a depth of, for example, 50 μm to 1 mm in the direction of the crankshaft. Forming range A
′ Is selected to be 10% to 50% with respect to the total width B in the direction perpendicular to the crankshaft, whereby the mating surface 11
A non-contact portion 15 that does not contact each other is formed between a and 12a. The lubricating oil passages 6a, 6b are open at the central portions of the mating surfaces 11a, 12a where the recessed portion 4 is not formed and communicate with each other, and no O-ring or the like is used.

FIG. 12 shows the state of the surface pressure between the mating surfaces 11a and 12a. (A) shows the case where the total forming area A'of the recessed portion 14 is 10% of the total width B, (b) ) Is 6
In the case of 0%, (c) exemplifies the case of 30%. C in the figure is the bolt position, the solid line is the bolt tightening force,
The chain line and the broken line respectively indicate the surface pressure when the in-cylinder pressure acts and when the inertial force acts. When the formation range A ′ of the slime portion 14 is 10% or less of the total width B, the surface pressure during the action of inertial force becomes substantially zero in the vicinity of the center, and the formation range A ′ is compared with the total width B. When the pressure is 50% or more, each surface pressure becomes large, so that the surface pressure does not become zero in the vicinity of the center, but the surface pressure when the in-cylinder pressure acts rapidly increases in the vicinity of 60%.

As described above, when the recessed portion 14 is small, the surface pressure in the vicinity of the center becomes low, and when the inertial force acts, the mouth is easily opened and fretting wear occurs. On the contrary, when the recessed portion 14 is large, The bolt tightening force and the surface pressure at the time of in-cylinder pressure become excessive near the boundary of the recessed portion 14, resulting in damage and wear, but if the formation range of the recessed portion 14 is appropriate, an appropriate surface pressure is maintained. Be done. FIG. 13 illustrates the relationship between the size of the thin portion 14 and the amounts of fretting wear and damage wear, and the solid line represents the fretting wear amount and the broken line represents the damage wear amount. That is, fretting wear begins to occur in the range of formation of the recessed portion 14 from about 10% and increases rapidly below that, and damage wear is 50%.
%, And the formation range of the recessed portion 14 is 10%.
% To 50% is considered appropriate,
By providing the recessed portion 14 in this range, both fretting wear and damage wear can be eliminated.

[0019]

As is apparent from the above description, in the first aspect of the present invention, the mating surface of the rod portion and the large end portion is provided with the recessed portion, and the mating surface is provided in the range of 20% to 70% with respect to the entire width. The non-contact portion is formed. Therefore, it is possible to concentrate the tightening force of the bolt on the contact part of the mating surface to maintain a high surface pressure for firm tightening, and do not contact the part near the center where fretting wear of the mating surface is likely to occur. Therefore, fretting wear due to insufficient tightening is prevented. Further, in the case where the opening of the lubricating oil passage is provided in a portion other than the recessed portion,
A sealing member such as an O-ring becomes unnecessary. Furthermore, by providing the recessed portion on the mating surface of the upper housing at the large end, it is possible to prevent stress concentration due to a thin portion on the mating surface side of the rod portion.

According to a second aspect of the present invention, a protrusion is provided on the mating surface of the upper end of the large end, and a recess is provided on the mating surface of the rod portion. A non-contact portion is formed between the recess and the bottom surface. Therefore, the rigidity of the upper housing is increased by the protrusion, the deformation of the housing during operation is reduced, and the bearing wear is reduced. In addition, the non-contact portion prevents fretting wear in the vicinity of the center, and furthermore, the projection and the recess are fitted together and the bolts are tightened to enable a strong connection.

A third aspect of the invention is to provide a recessed portion on at least one bolt fastening portion of the mating surfaces of the rod portion and the upper housing of the large end portion so that the total width is 10% to 5%.
A non-contact portion is formed on the mating surface in the range of 0%. Therefore, the tightening force of the bolt is concentrated on the contact portion of the mating surfaces, the surface pressure near the center is kept high, the mouth opening due to the inertial force is prevented, and the fretting wear is prevented.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view of an embodiment of the first invention.

FIG. 2 is a plan view of a mating surface of a large end portion and a rod portion of the embodiment.

FIG. 3 is a graph showing a surface pressure state of a mating surface of the example.

FIG. 4 is a graph showing a worn state of a mating surface of the example.

FIG. 5 is a partially cutaway front view of a main part of another embodiment.

FIG. 6 is a plan view of a mating surface of a large end portion and a rod portion of the embodiment.

FIG. 7 is a partially cutaway front view of an essential part of an embodiment of the second invention.

FIG. 8 is a plan view of a mating surface of the large end portion and the rod portion of the embodiment.

FIG. 9 is a plan view of a mating surface of a large end portion and a rod portion of another embodiment.

FIG. 10 is a partially cutaway front view of an essential part of an embodiment of the third invention.

FIG. 11 is a plan view of a mating surface of the large end portion and the rod portion of the embodiment.

FIG. 12 is a graph showing a surface pressure state of a mating surface of the example.

FIG. 13 is a graph showing a worn state of a mating surface of the example.

[Explanation of symbols]

1 connecting rod A few bolts 4,14 Null part 5,15 Non-contact part 6a, 6b Lubricating oil passage 11 large end 11-1, 11-2 housing 11a, 12a Mating surface 12 Rod part 21 Projection 21a end face 22 recess 22a bottom

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiroaki Umehara             1-32 Chayamachi, Kita-ku, Osaka Yanmar Day             Inside the company (72) Inventor Toru Takahashi             1-32 Chayamachi, Kita-ku, Osaka Yanmar Day             Inside the company (72) Inventor Shita Akimoto             1-32 Chayamachi, Kita-ku, Osaka Yanmar Day             Inside the company

Claims (5)

[Claims] 1. A three-part connecting rod which is divided into a central part and an upper part of the large end, and which is integrated by bolting together the mating surfaces of the divided parts. 20% of the total width in the direction perpendicular to the crankshaft by forming a hollow part in at least one central part of the surface
A connecting rod for an internal combustion engine, characterized in that a non-contact portion where the mating surfaces do not contact each other is formed in the range of 70 to 70%. 2. The connecting rod for an internal combustion engine according to claim 1, wherein an opening at a mating surface of the lubricating oil passage extending from the large end portion to the rod portion is provided in a portion other than the recessed portion. 3. The connecting rod for an internal combustion engine according to claim 2, wherein the recessed portion is provided on the mating surface of the large end portion. 4. A three-part connecting rod which is divided into a central portion and an upper portion of the large end and which is integrated by bolting together the mating surfaces of the respective divided portions. In addition, a recess is provided on the mating surface of the rod portion, and a non-contact portion is provided between the end surface of the protrusion and the bottom surface of the recess. A characteristic connecting rod for internal combustion engines. 5. A three-part connecting rod which is divided into a central part and an upper part of the large end and which is integrated by bolting the mating surfaces of the respective divided parts together. The non-contact portions where the mating surfaces do not contact each other in the range of 10% to 50% in total with respect to the total width in the direction perpendicular to the crankshaft are bolted by forming the recessed portions on both side edges of at least one of the surfaces. A connecting rod for an internal combustion engine, characterized in that it is formed in a tightened portion.