JPH0763216A - Connecting rod for internal combustion engine - Google Patents

Abstract

PURPOSE:To reduce a bending moment to be applied to bolts and improve durability of the bolts in a connecting rod wherein a large end which is divided into two is fastened by means of the paired bolts, and positione by a pair of knock pins. CONSTITUTION:A large end 4 of a connecting rod 1 can be divided into a rod main body 7 and a cap 8. Both members 7, 8, sandwiching a large bearing port 6 on both sides in a widthwise direction, are fastened by a pair of bolts 9. The rod main body 7 and the cap 8 are positioned by a pair of knock pins 12 arranged adjacently to the bolts 9. An axis of each knock pin 12 is arranged nearer the large bearing port 6 than an axis of each bolt 9. Namely, a span S1 of the knock pin 12 is sat smaller than a span S2 of the bolt 9. A bending moment generated at a large end 6 is received by the knock pins 12, so that the bending moment applied to the bolts 9 is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connecting rod used for connecting a piston and a crankshaft in an internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, as a technique relating to this type of connecting rod, for example, one disclosed in Japanese Utility Model Laid-Open No. 4-49221 can be cited. In this connecting rod, the large end of the column is divided into a rod body and a cap. The rod main body and the cap are fastened with a pair of bolts on both sides in the width direction with a bearing hole interposed therebetween. Here, since a bolt that does not require a nut is used, it contributes to weight reduction of the connecting rod. Further, pin rings are respectively interposed between the bolts and the bolt insertion holes formed in the rod body and the cap. Further, a pair of knock pins are used to connect the rod body and the cap, and the positioning accuracy of the rod body and the cap is improved by these knock pins. Here, each knock pin is arranged close to each bolt, and the distance from the bearing hole at the large end to the shaft center of each bolt is the same as the distance from the bearing hole to the shaft center of each knock pin. Has become. That is, the span of both bolts and the span of both knock pins are the same.

[0003]

By the way, in the above-mentioned prior art, when the connecting rod is used in an internal combustion engine, a bending moment acts around both bolts due to the inertial force at the large end of the connecting rod. It will be. However, in the above connecting rod, since the distance from the bearing hole to the axis of each bolt is the same as the distance from the bearing hole to the axis of each knock pin, most of the bending moment at the large end is The burden was on the bolt side, and the amount of burden on the knock pin was extremely small. Therefore, it is necessary to improve the durability by the amount of the bending moment applied to the bolt side, and therefore, it is necessary to increase the bolt diameter and the pin ring diameter. However, when the bolt diameter and the pin ring diameter are increased, the weight of the connecting rod is increased, which is against the intention of weight reduction, which is a problem.

The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to connect a large end portion divided into a rod body and a cap with a pair of bolts and to position with a pair of knock pins. In order to provide a connecting rod for an internal combustion engine, which can reduce the bending moment applied to the bolt and improve the durability of the bolt.

[0005]

In order to achieve the above object, the present invention is a connecting rod for connecting a piston and a crankshaft in an internal combustion engine, which has a bearing hole connected to the crankshaft. The large end is divided into a rod body and a cap, and the rod body and the cap are fastened with a pair of bolts with bearing holes on both sides in the width direction. The structure is such that a pair of knock pins respectively arranged adjacent to the bolts are used for positioning, and the shaft center of each knock pin is arranged closer to the bearing hole than the shaft center of each bolt.

[0006]

According to the above construction, the shaft centers of both knock pins arranged on both sides of the large end in the width direction with the bearing hole interposed therebetween are arranged closer to the bearing hole than the shaft centers of the bolts. Therefore, the bending moment generated at the large end portion during operation of the internal combustion engine is also borne by both knock pins, and the bending moment applied to the bolt is reduced accordingly.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which a connecting rod of an internal combustion engine according to the present invention is embodied will be described in detail below with reference to FIGS.

FIG. 1 is an exploded front view showing the structure of the connecting rod 1 of this embodiment. The connecting rod 1 connects a piston of an internal combustion engine and a crankshaft, and includes a rod-shaped column 2 and small ends 3 and large ends 4 provided at both ends thereof. The small end portion 3 is provided with a small bearing hole 5 connected to the piston pin. A large bearing hole 6 connected to the crank pin is provided in the large end portion 4. The large end portion 4 is divided into a rod body 7 and a cap 8 that are continuous with the column 2, and the rod body 7 and the cap 8 are paired with the large bearing hole 6 interposed therebetween on both sides in the width direction. The structure is such that it can be tightened with bolts 9.

Here, a bolt 9 that does not require a nut is adopted, and the bolt 9 has a male screw 9 only at its tip.
a is formed. Further, bolt holes 10 and 11 corresponding to the bolts 9 are formed in the rod body 7 and the cap 8 at the large end portion 4, respectively. Then, with respect to the bolt hole 10 on the rod body 7 side, a female screw 10a is formed only in the upper half thereof. On the other hand, no female screw is formed in the bolt hole 11 on the cap 8 side. Thus, the bolt 9 is of the nutless type, so that the weight of the connecting rod 1 is reduced.

Further, in this embodiment, the rod body 7 and the cap 8 are positioned by a pair of knock pins 12 arranged adjacent to each bolt 9. That is, in the rod body 7 and the cap 8 at the large end portion 4, the pin holes 13 and 14 corresponding to the knock pins 12 are formed.
Are formed respectively. These pin holes 13, 14
Are arranged closer to the large bearing hole 6 than the bolt holes 10 and 11 described above. That is, in FIGS. 2 and 3, the end faces 7a of the rod body 7 and the cap 8 which are butted against each other,
8a is shown. As shown in these figures, in this embodiment, the positions of the pin holes 13 and 14 are formed closer to the large bearing hole 6 than in the conventional position. Further, in this embodiment, the distance between the center P1 of the bolt holes 10 and 11 and the center P2 of the pin holes 13 and 14 is the same as the conventional one, but the pin holes 13 and 14 approach the large bearing hole 6 respectively. It is arranged. With the above configuration, the axis of each knock pin 12 is arranged closer to the large bearing hole 6 than the axis of each bolt 9. That is, as shown in FIG. 1, the span S1 of both knock pins 12 is the span S2 of both bolts 9.
It is set to be smaller than.

To connect the connecting rod 1 configured as described above to a crank pin of a crank shaft (not shown), the following procedure is performed. That is, with the cap 8 removed from the rod body 7 at the large end portion 4, each pin hole 13 of the rod body 7 or the cap 8 is removed.
Half of each pin 12 is previously fitted into each pin hole 14 of the above. Then, the large bearing hole 6 on the rod body 7 side is fitted to the crank pin, and the large bearing hole 6 on the cap 8 side is fitted to the crank pin from the opposite side. At this time,
Due to the action of both knock pins 12, the rod body 7 and the cap 8 are accurately positioned and coupled,
It is possible to improve the assembling precision of both 7 and 8.

Thereafter, the bolts 9 are sequentially inserted into the bolt holes 11 and 10 from the cap 8 side, and the male screw 9a of each bolt 9 is fastened to the female screw 11a of the bolt hole 10. By this tightening, as shown in FIG. 4, the rod body 7 and the cap 8 are integrally coupled, and the connecting rod 1 is coupled to the crank pin 15.

On the other hand, as is well known, the connecting rod 1 is connected to a piston through a piston pin inserted into a small bearing hole 5 in the small end portion 3. Therefore, when the connecting rod 1 is assembled to an internal combustion engine and rotates during its operation, as shown by a stress distribution line L in FIG. 4, the large end 4 is bent by the inertial force. A moment is generated. Then, the bending moment acts around the both bolts 9. However, in this embodiment, since the shaft ends of both knock pins 12 are arranged closer to the large bearing hole 6 than the shaft centers of both bolts 9 at the large end portion 4, bending that occurs at the large end portion 4 is caused. The moment is also applied to both knock pins 12, and the bending moment applied to both bolts 9 is correspondingly reduced.

The graph of FIG. 5 shows the relationship between the inertial force at the large end 4 and the bending moment of the bolt 9 caused by it. From this graph, it can be seen that the bending moment in this example is smaller than that in the conventional example. Here, the bending moment is reduced in the range of "2 to 10%".

As a result, the bending moment applied to both bolts 9 can be reduced and the durability of both bolts 9 can be improved. That is, the durability of the bolt 9 can be afforded, and there is no inconvenience even if the strength of the bolt 9 itself is lowered to some extent. Specifically, as can be seen from the stress distribution line L shown in FIG. 4, the bending moment generated in the bolt 9 is maximum at the portion of the male screw 9a. According to the configuration of this embodiment, the male screw is There is no inconvenience even if the strength of 9a is lowered to some extent. Therefore, the bolt 9 can be made smaller in diameter including the portion of the male screw 9a, and thus the weight of the connecting rod 1 can be reduced.
Also, when the bolt 9 has a reduced diameter, the wall thickness d of the large end portion 4, that is, the wall thickness d of the rod body 7 and the cap 8 can be reduced as shown in FIGS. It is also possible to reduce the size and weight of device 1.

Further, in this embodiment, the bolt holes 10 and 11 are
The pin holes 13 and 14 are brought closer to the large bearing hole 6 while keeping the distance between the center P1 of the pin hole and the center P2 of the pin holes 13 and 14 the same as the conventional one. Therefore, the positions of the pin holes 13 and 14 are brought closer to the center of the large end portion 6 in the wall thickness direction, and the wall thickness d of the large end portion 4 can be reduced accordingly. Therefore, also in this sense, the connecting rod 1 can be reduced in size and weight.

Further, in this embodiment, unlike the conventional connecting rod in which the pin ring is interposed between the bolt and the bolt insertion hole, the pin ring is omitted, so that the connecting rod 1 is correspondingly provided. It is also possible to reduce the weight and the size.

The present invention is not limited to the above-described embodiment, but may be implemented as follows with a part of the configuration appropriately changed without departing from the spirit of the invention. (1) In the above embodiment, the connecting rod 1 using the nutless type bolt 9 is embodied, but it may be embodied as a connecting rod using a nut for the bolt.

(2) In the above embodiment, the bolt holes 10, 1
The pin holes 13 and 14 were arranged close to the large bearing hole 4 while the distance between the center P1 of No. 1 and the center P2 of the pin holes 13 and 14 was the same as the conventional one. On the other hand, the pin hole may be arranged closer to the large bearing hole while changing the distance between the center of the bolt hole and the center of the pin hole as compared with the conventional one.

[0020]

As described above in detail, according to the present invention, the large end portion is divided into the rod main body and the cap, and the pair of bolts are formed on both sides in the width direction with the bearing holes interposed therebetween. By tightening, the rod body and the cap are positioned by a pair of knock pins arranged adjacent to each bolt, and the axis of each knock pin is arranged closer to the bearing hole than the axis of each bolt. Therefore, the bending moment generated at the large end is also carried by both knock pins, and the bending moment applied to the bolt is reduced accordingly. As a result, the excellent effect that the bending moment applied to the bolt can be reduced and the durability of the bolt can be improved is exhibited.

[Brief description of drawings]

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

FIG. 2 is a diagram showing an end surface of a rod body in one embodiment.

FIG. 3 is a diagram showing an end surface of a cap in one embodiment.

FIG. 4 is a front view showing an assembled state of a large end portion of a connecting rod in one embodiment.

FIG. 5 is a graph showing a relationship between an inertial force and a bending moment at a large end portion of a connecting rod in one example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Connecting rod, 4 ... Large end part, 6 ... Large bearing hole, 7 ... Rod main body, 8 ... Cap, 9 ... Bolt, 12
Is a knock pin, 15 ... a crank pin.

Claims (1)

[Claims] 1. A connecting rod for connecting a piston and a crankshaft in an internal combustion engine, wherein a large end portion having a bearing hole connected to the crankshaft is divided into two parts, a rod body and a cap, The rod main body and the cap are tightened by a pair of bolts sandwiching the bearing hole on both sides in the width direction thereof, and the rod main body and the cap are respectively arranged adjacent to the bolts. A connecting rod for an internal combustion engine having a structure for positioning by a knock pin, wherein the axis of each knock pin is arranged closer to the bearing hole than the axis of each bolt.