JPS605132Y2 - Aluminum alloy connecting rod - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a connecting rod that connects a piston and a crankshaft of an internal combustion engine via a piston pin and a crank pin, respectively.

As shown in Fig. 1, the conventional connecting rod has a small end attached to a large end of a rod body 5 which is pivotally connected to a piston 3 via a piston pin 1, and has a structure that has resistance to break-in and resistance under high speed and high load conditions. In order to improve seizure resistance, fatigue resistance, etc., a bearing metal 7 made of copper-lead alloy or high-tin aluminum alloy is attached, and the cap 9 is screwed and fixed to the large end of the rod body 5 with bolts 11 and nuts 13. It is rotatably supported on the crank pin 15.

Note that 17 is between the piston pin boss and piston pin 1,
It also contains oil to supply lubricating oil for cooling the piston.

The conventional connecting rod structure as described above has various drawbacks because it uses a bearing metal.

That is, the use of such a bearing metal increases the material cost, and the process of machining and assembling the bearings is required, which complicates the manufacturing process and tends to increase the manufacturing cost.

Further, it is cumbersome as it requires adjustment of the amount of protrusion (amount of crush).

Furthermore, when the connecting rod is in use, the bearing metal rotates around the crank pin, and the oil filling therein may not align with the oil filling in the rod body, resulting in seizure.

In this invention, the connecting rod body and cap are made of aluminum alloy, and the connecting rod itself functions as a bearing metal, thereby eliminating the use of bearing metal and eliminating the various drawbacks caused by the use of bearing metal. do.

The aluminum alloy connecting rod itself acts as a bearing metal, and is seizure resistant even under high speed and high load.
It satisfies fatigue resistance, reduces friction loss, improves fuel efficiency, and eliminates bearing metal, reducing costs.

However, when designing bearings to achieve a specified bearing clearance under high speed and high load conditions, aluminum alloy connecting rods have a higher coefficient of thermal expansion than the steel and cast iron that make up the crankshaft. The diameter of the bearing part tends to be smaller than that of the crank pin, and there is a risk of seizure.

Therefore, the sliding surface of the connecting rod with the crankshaft has a predetermined surface roughness to form an oil pool, improving seizure resistance and wear resistance during cold startup, and improving initial break-in. It is.

The surface roughness of the sliding surface is in the range of 1 to 4 μmRz based on the ten-point average roughness defined in JISBO601.

If it is less than this range, a predetermined amount of oil will not accumulate when the engine is stopped, and seizure is likely to occur when the engine starts.

On the other hand, if the above range is exceeded, a large amount of oil will accumulate on the sliding surface and there will be insufficient lubricating oil to other parts.

In order to form a sliding surface with a surface roughness within the above range, liquid honing, anodizing surface treatment, or machining can be employed, but liquid honing is particularly effective in obtaining a sliding surface suitable for oil reservoirs. Optimal.

Referring to FIG. 2, the connecting rod of the present invention is similar to the conventional connecting rod shown in FIG. The end portion includes a cap 9 surrounding a crank pin 15 fixed by a bolt 11 and a nut 13.

The differences from conventional connecting rods are that the connecting rod body 5 and cap 9 are made of high-strength aluminum alloy, that the bearing metal 7 (Fig. 1) is not used, and that the connecting rod body 5 and cap 9 are made of high-strength aluminum alloy. The sliding surfaces 5a, 9a of No. 9 are
The oil reservoir is formed with a surface roughness of mRz, preferably by liquid honing.

Note that 17 is an oil filler formed in the connecting rod body 5.

The present invention described above makes it possible to obtain a connecting rod that has low manufacturing costs and can reduce wear loss and improve fuel efficiency.

[Brief explanation of the drawing]

FIG. 1 is a front view of a conventional connecting rod, FIG. 2 is a front view of the connecting rod of the present invention, and FIG. 3 is a view taken along arrows 1--2 in FIG. 3...Piston, 5...Connecting rod body, 9...Connecting rod cap, 5a, 9a...Sliding surface, 15----
--Crank pin.

Claims (1)

[Claims for Utility Model Registration] 1. In a connecting rod that connects a piston and a crankshaft of an internal combustion engine via a piston pin and a crank pin, respectively, the connecting rod is made of an aluminum alloy, and the contact surface with the crank pin is 4μmR
This is an aluminum alloy connecting rod that can be mounted on a crank pin without the need to install a bearing metal due to the Z surface roughness and oil sump. 2. The aluminum alloy connecting rod according to claim 1, wherein the contact surface is liquid honed.