JPH048906A - Connecting rod for internal combustion engine - Google Patents

Abstract

PURPOSE:To lighten an internal combustion engine in weight and improve its durability by assembling a steel made cap on an alminium alloy made connecting rod main body divided at its large edge part and providing a female screw part at least on a part of a cap side through hole and a bolt locking part on the connecting rod main body side. CONSTITUTION:A connecting rod is divided into an alminium alloy made connecting rod main body 1 and a steel made cap 2 on its large edge part 5, and a falling preventive ring 15 is provided on a through hole 6 on the side of the connecting rod main body 1 of s bolt 11 to connect the two. Subsequently, a female screw part 9 is formed on a through hole 8 on the side of the cap 2. Accordingly, as the female screw part 9 to screw a bolt 12 is on the side of the cap 2 with large strength, it is possible to lighten the whole system, give through strength and durability to it and easily carry out assembling work.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to an improvement in a connecting rod that connects a piston pin and a crank pin of an internal combustion engine.

As shown in FIG. 7, a connecting rod for a conventional internal combustion engine has a small end portion 23 connected to a piston pin, a large end portion 24 connected to a crank pin, and a rod portion 25 between the two ends.
It has the function of transmitting the reciprocating motion of the piston as rotational motion of the crankshaft. Additionally, this connecting rod has a mating surface 2 passing through the center of the large end 24.
6, the connecting rod body 2 includes a small end portion 23 and a rod portion 25, and a semicircular cap 22, both of which are connected to a pair of bolts 2.
connected by 9.

Here, the bolt 29 is normally screwed in from the cap 22 side as shown in the figure, since it is necessary to perform the tightening operation from the cap 22 side for convenience in assembling the internal combustion engine. In other words, the female threaded portion 28 is formed on the connecting rod body 2] side, and the bolt 29 inserted into the bolt insertion hole 27 on the cap 22 side is inserted into the female threaded portion 28.
It has a structure in which it is screwed together with 8.
(See Publication No. 823, etc.).

In some cases, a stud bolt is installed in advance in the female threaded portion 28 on the side of the connecting rod body 21, and the cap 22 is fixed using a nut.

Problems to be Solved by the Invention In recent years, in order to reduce the weight of the entire internal combustion engine, attempts have been made to form the above-mentioned connecting rods from a lightweight aluminum alloy, but aluminum alloys have high notch sensitivity and fatigue strength. Therefore, in the conventional configuration described above, the female threaded portion 2 provided on the connecting rod body 21 side
Fatigue-induced damage is likely to occur from the valley of No.8.

A Means to Solve the Problems Therefore, the present invention makes only the main connecting rod body made of aluminum alloy, and provides a female threaded portion on the steel cap side, so that the bolt tightening work can be done from the cap side. did.

That is, the connecting rod for an internal combustion engine according to the present invention includes a connecting rod body made of aluminum alloy and a cap made of steel, which are divided at the large end.
5), a hole formed through the main body side), a female threaded portion formed in at least a part of the through hole provided on the cap side, and a connecting hole. A bolt that has a retaining part on the rod body side, a male thread part on the distal end side, and a polygonal hole for tightening on the distal end surface, and is inserted between this bolt and the bolt insertion hole. It is characterized by being equipped with a fall prevention ring.

Function In the above configuration, the bolt is inserted from the connecting rod main body side, and the male threaded portion on the distal end side is screwed into the female threaded portion provided on the steel cap.

In other words, only a port insertion hole without a female thread is formed through the aluminum alloy connecting rod body side.

The tightening operation of the bolt is performed from the cap side using a polygonal hole formed in the front end surface of the bolt. At this time, the bolt is held in the bolt insertion hole by the drop-off prevention ring, and is prevented from falling off.

Embodiment FIG. 1 shows an embodiment of a connecting rod according to the present invention. As described above, this connecting rod has a small end 3 connected to the piston pin, a large end 5 connected to the crank pin, and a rod portion 4 between the two, and the center of the large end 5 is The connecting rod main body 1 includes a small end portion 3 and a loft portion 4, and a cap 2 has a semicircular shape. The connecting rod body 1 is made of lightweight aluminum alloy, and the cap 2 is made of steel, which has better notch sensitivity and fatigue strength than aluminum alloy.

On both sides of the big end 5 of the connecting rod body l,
A port insertion hole 6 is formed through the port.

The shoulder portion 7 of the connecting rod main body l, in which one end of the port insertion hole 6 is open, is machined into a flat surface. In addition, at the end of the port insertion hole 6 on the shoulder 7 side, there is a large diameter 1tJ6 which is slightly larger in diameter than other general parts.
A is provided.

On the other hand, in the rj through holes 8 provided on both sides of the cap 2,
A female threaded portion 9 is formed. The end of the through hole 8 on the mating surface 10 side is a large diameter portion 8a without a thread (see FIG. 2).

This large diameter portion 8a serves as a guide during assembly q as will be described later, and its diameter is slightly larger than the outer diameter of the thread of the male threaded portion 13 of the bolt II.

The bolt 11 that connects the connecting rod body 1 and the cap 2 is inserted from the connecting rod body 1 side, and has a circular head 12 at one end of the shaft ff1N1a that comes into contact with the shoulder 7 as a stopper. and has a male threaded part 13 on the distal end side which is threadedly engaged with the female threaded part 9 on the cap 2 side. Further, as shown in FIGS. 3 and 4, a polygonal hole for tightening work, specifically a hexagonal hole 14, is formed on the tip end surface on the male threaded portion 13 side. Therefore, as will be described later, the bolt 11 can be tightened from the cap 2 side using a hexagonal wrench.

Then, when tightening from the cap 2 side, bolt 1
A cylindrical drop-off prevention ring ]5 is inserted between the large diameter portion 6a of the port insertion hole 6 and the shaft portion 11a of the bolt 11 in order to hold it in the bolt insertion hole 6. This fall prevention ring 15 is made of a polymeric material with excellent self-lubricating properties to allow rotation of the bolt 11, and is attached to the inner circumferential surface of the large diameter portion 62L of the port insertion hole and the outer circumferential surface of the bolt shaft portion 11a, respectively. It is a tight fit.

FIG. 5 shows the procedure for assembling the connecting rod configured as described above. First, as shown in (&), the bolt 11 is inserted into the bolt insertion hole 6 of the connecting rod body 1 to prevent it from falling out. Insert together with ring 15. Here, the bolt 11 is held relatively firmly by the falling-off prevention ring 15, and the temporarily assembled state as shown is reliably maintained. Next, as shown in (b), the cap 2 is butted against the tips of the pair of poles If, and each bolt is
Perform step 1 tightening. At this time, the bolt 11 is
It will be pushed up from the side, but the fall prevention ring 15
This will prevent its falling off. Furthermore, when the cap 2 is brought into contact with the tip of the bolt 11, the tip of the bolt 11 fits into the large diameter portion 8a of the through hole 8 on the cap 2 side, making it very easy to align the cap 2 and the bolt II. becomes. Note that the pair of bolts 11 may be alternately tightened little by little, but if the pair of hex wrenches 16 are configured to rotate synchronously, the tightening work of both bolts 11 will be made easier. be able to. By the above steps (
As shown in c), the assembly of the connecting rod is completed.

Therefore, with the piston and crankshaft assembled to the cylinder block, the connecting rod can be assembled from the crankcase opening side of the cylinder block without any hindrance.

Next, FIG. 6 shows a different embodiment of this invention.

In this embodiment, the shaft portion 11a of the bolt 11 itself is formed in a tapered shape as a part to prevent the bolt 11 from coming off, and the formation of the head 12 is omitted. The bolt insertion hole 6 on the connecting rod body 1 side into which this bolt 11 is inserted also has a tapered shape corresponding to the bolt II. Further, in this embodiment, a large diameter portion 6a is formed on the mating surface IO side of the bolt insertion hole 6, and a fall prevention ring 15 is disposed here.

According to the configuration of this embodiment, by omitting the head 12 of the bolt 11, it is possible to further reduce the weight of the entire connecting rod.

Effects of the Invention As is clear from the above explanation, in the connecting rod for an internal combustion engine according to the present invention, a significant weight reduction can be achieved by making the connecting rod main body made of aluminum alloy, and the internal thread into which the bolt is screwed is Since the portion is formed on the steel cap side, damage due to fatigue can be prevented and sufficient strength and durability can be obtained.

In addition, since bolts can be tightened from the cap side in the same way as when inserting bolts from the cap side, the connecting rod can be assembled without any problems when the piston and crankshaft are assembled to the cylinder block. This does not complicate the assembly work.

[Brief explanation of drawings]

Fig. 1 is a partially cutaway sectional view showing an embodiment of the connecting rod according to the present invention, Fig. 2 is a sectional view of the main part of the cap, and Fig. 3 is a partially cutaway sectional view of the bolt in this embodiment. Figures 4 and 4 are the same (a front view of the bolt, Figure 5 is a process explanatory diagram showing the procedure for assembling this connecting rod, and Figure 6 is a partially cutaway diagram showing a different embodiment of the connecting rod according to the present invention). 7 is a partially cutaway sectional view showing an example of the configuration of a conventional connecting rod. ■ Connecting rod body; 2. Cap;
6・Bolt insertion hole, 8・Through hole, 9・Female thread part, 1
1...Bolt, 12.Head, 13...Male thread part, I
4...Hexagonal hole, 15 - Fall-off prevention ring. Figure Figure Figure Figure Hexagonal Hole Figure Figure Figure

Claims (1)

[Claims] (1) At least an aluminum alloy connecting rod body and a steel cap divided at the large end, a bolt insertion hole formed through the connecting rod body side, and a through hole formed on the cap side. A bolt that has a female thread formed in a part, a retaining part on the connecting rod body side, a male thread on the tip side, and a polygonal hole for tightening on the tip surface; A connecting rod for an internal combustion engine, comprising a fall prevention ring inserted between the bolt insertion hole and the bolt insertion hole.