JPH01158212A - Shaft subjected to oil leak preventing measure - Google Patents

Abstract

PURPOSE:To prevent oil leak so as to reduce the manufacturing cost of the title shaft by forming a nitrided layer on a sliding portion along an oil seal or fitting a sleeve having the nitrided layer on its surface along the same portion. CONSTITUTION:A sleeve 7 is fitted to a sliding portion along on oil seal 3 in a crank shaft 2. An O-ring 11, a flywheel 22 and the retainer oil seal 4 of a cylinder block are provided. The sleeve 7 sliding along the oil seal 3 has a nitrided layer 10 on its surface. The base material of the sleeve 7 is martensite group stainless steel. The crank shaft 2 is made of carbon steel. Thus, the effect of oil leak prevention is demonstrated and also the manufacturing cost can be reduced.

Description

[Detailed Description of the Invention] <Industrial Application Fields> The present invention relates to a rotating shaft, such as a crankshaft or a camshaft of an engine, which passes through a partition wall between an oil-filled chamber and an outside space (non-oil chamber, atmospheric space). It is related to.

(Prior art) For example, in an engine, as shown in FIG.
In the portion indicated by , the crankshaft 2 extends from the interior 8 to the exterior 9 of the engine body 1 . By the way, since the inside of the engine body l is filled with oil, the part indicated by arrow A is from inside 8 to outside 9.
It must be sealed to prevent oil from leaking.

Conventionally, the sealing method has been to use a rubber oil seal 3 as shown in Fig. 5. In the figure, 5 is an oil pan, 14 is a cylinder block, and 22 is a frying pan. It's a wheel.

Therefore, the crankshaft 2, which is tightened by the oil seal fixed to the engine body l, slides with the oil seal 3 as it rotates, but in such a seal structure, the harder the shaft, the harder the shaft is. It is also said that the smaller the surface roughness, the better.

Such a seal structure has the following drawbacks.

That is, since one side of the oil seal 3 is surrounded by the outside 9, dirt, sand, etc. may invade from the outside 9, and the oil seal 3 may get caught in them.
Abnormal wear occurs on the sliding surface 6 of the crankshaft 2 (ie, the portion that contacts the oil seal 3).

This abnormal wear also occurs when foreign matter gets mixed into the oil or when the oil deteriorates, and especially when deteriorated oil is used in a diesel engine, ``carbon suit gets in,''
Since the oil seal gets caught in the carbon suit, the wear on the crankshaft and camshaft becomes severe.

As a countermeasure against such wear, it is conceivable to increase the hardness of the moving parts of the shaft (usually Hv=200 to 300) by induction hardening or the like. On the other hand, it is possible to form a hardened layer by re-melting and hardening using a high-density energy source such as pulsed TIG or a laser beam.
Publication No. 6241, Japan Institute of Invention and Innovation Publication Technical Report No. 84-13056
Disclosed in the issue.

(Problems to be Solved by the Invention) However, the above countermeasure methods have the following problems.

First, although induction hardening provides hardness, the surface becomes rough, so the surface must be polished afterwards to make it smooth, but this polishing work is extremely difficult. Furthermore, even if the hardness is increased, the wear resistance is not sufficient, and there is little effect especially in the case of a diesel engine with a large amount of carbon suit.

In addition, the method of forming a hardened layer on the sliding surface by remelting is
The hardness is only about 600 Hv, and the anti-wear effect is not sufficient, especially when there is a large amount of carbon suit in a diesel engine, -1 hardly shows any effect.

In this way, once wear occurs in the oil seal portion of the shaft, the problem develops that the entire shaft must be replaced.

The present invention has been made to solve the above-mentioned conventional problems, and its purpose is to provide a shaft that can prevent oil leakage with almost no wear at the oil seal portion. .

<Means for Solving the Problems> The shaft in which the oil leakage prevention measure of the present invention which can achieve the above object is provided has a nitrided layer formed on the sliding part with the oil seal, or It is characterized in that a sleeve having a nitride layer on the surface is fitted.

If the shaft is a crankshaft or camshaft,
These shafts are usually made of steel (JIS 550C)
It is made of spheroidal graphite cast iron (JISFCD70),
With this component, even if the shaft is directly nitrided, the desired hardness and depth cannot be obtained, so it is preferable to fit a sleeve on which a nitrided layer is formed onto the shaft. The above-mentioned sleeve with a nitrided layer on its surface has a nitrided layer with a hardness of HV900 to 1600 formed on a base material made of martensitic stainless steel in which fine carbides mainly composed of C are precipitated. It is preferable that the hardness of the nitrided layer is Hv900.
If it is less than 1,600 Hv, the wear resistance will be insufficient, and if it is more than 1600 Hv, cracks will occur during processing and the wear of the oil seal will increase. The thickness of the nitrided layer (Hv700 or more) should be 5 to 1, because if it is less than 5IL, the durability will not be sufficient, and if it is more than 1OOIL, the processing time will become longer and the processing cost will increase.
00t is good.

The sleeve base material may be any material that can form the above-mentioned nitrided layer, and is approximately CO15~4%, Cr12, O~
A steel containing 19.0% iron and the balance iron is preferable, or it may further contain elements contained in general steel.

If the shaft is made of such a material, it is of course possible to form a nitrided layer directly on the shaft itself, but in order to be able to nitride many parts at the same time, it is better to nitride the sleeve to which it is fitted. is advantageous.

Since the shaft constructed as described above is provided with a hard nitrided layer, no wear occurs even if foreign matter enters the sliding portion with the oil seal. That is, the nitrided layer prevents oil leakage.

In particular, the fact that a sleeve having a nitrided layer can be fitted makes it possible to prevent oil leakage even from a shaft made of a material in which a nitrided layer cannot be formed, thereby improving the efficiency of the nitriding process.

<Examples> The present invention will be described in more detail below with reference to examples of shafts in which oil leak prevention measures according to the present invention have been taken.

Embodiment FIG. 1 is a partial sectional view showing a seal portion on the rear side of an engine to which a crankshaft is attached according to an embodiment. A sleeve 7 is fitted into the crankshaft 2 at a portion that slides with the oil seal 3. In this figure, 11 is an O-ring, 22 is a flywheel, and 4
is the cylinder block retainer oil seal.

As shown in Fig. 2, the sleeve 7 that slides with the oil seal 3 has a nitrided layer on its surface, and its base material is martensitic stainless steel (C1.0%, Si0.8%
, Po, 02%, So, 02%, Cr1a&, balance Fe
). The crankshaft 2 to which the sleeve 7 is fitted is made of carbon steel (JIS 550C).

The nitrided layer 10 of the sleeve 7 has a base material surface roughness of 1 by grinding.
．． Finished to 61LRz, then heated at 550℃ in NH Yugas
After performing nitriding treatment for 10 hours to form a hard layer, grinding (10 g) was performed to obtain a surface roughness of 1.41 LRz. The surface hardness of the nitrided layer is Hv 1200
”, and the thickness of the nitride layer having a hardness of Iv700 or more (in terms of cross-sectional hardness distribution) is 40 l.

After forming the nitrided layer, the sleeve with an O-ring fitted into the inner circumferential groove is press-fitted into the crankshaft to obtain a crankshaft in which the sleeve having the nitrided layer is fitted to the sliding portion with the oil seal. Ta.

Test Examples Comparative Examples 1 to 3 shown in the table below and the crankshaft fitted with the sleeves of the above examples were used in an actual engine.
Durability tests were conducted on each shaft. 1800cc 4-cylinder 4-stroke diesel engine, 52000 rpm
This is a high-speed durability test of 200 hours under full load. Oil is not changed. The oil seal used was a silicone oil seal. The material and properties of the sliding part (sleeve) between the crankshaft oil seal and the tested crankshaft are shown in the table below.

Figure 5 shows the amount of wear on the sliding parts of each shaft with the oil seal after the durability test on the material and properties of the outer sleeve. From the figure, it can be seen that even in a test using oil with a large amount of deteriorated carbon suit, the nitrided layer-formed products of the examples exhibited significantly less wear than the shafts of Comparative Examples 1 to 3 and were in good condition. The quenched and tempered product of Comparative Example 1 had a lot of wear, and oil leakage was observed at the end of the test. Furthermore, it can be seen that under the present test conditions, as seen in Comparative Example 2, even if induction hardening is performed, the effect of reducing wear is small.

<Effects of the Invention> As is clear from the above explanation, the shaft in which the oil leakage prevention measures of the present invention are taken has extremely little wear due to the formation of a hard nitrided layer in the sliding part with the oil seal. , both have excellent oil leakage prevention effects over a long period of time.

In addition, if it is difficult to form a nitrided layer directly on the shaft itself, a hard nitrided sleeve may be fitted and the oil seal may slide with it, so it is possible to Can also be applied to shafts,
It also has the effect of reducing manufacturing costs.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a main part showing a contact portion of a crankshaft with an oil seal in which an oil leak prevention measure according to an embodiment has been taken. Figure 2 is an enlarged sectional view of the main parts of the sleeve fitted to the shaft of one example, Figure 3 is a graph showing the durability test results of the crankshafts of each example and comparative example, and Figure 4 is the engine part. Sectional View FIG. 5 is an enlarged sectional view of the arrow A section in FIG. 4. In the diagram: 2...Crankshaft 3...Oil seal 7
...Sleeve l O-...Nitrided layer patent applicant Toyota Motor Corporation representative Patent attorney Yumi Kaly (2 idiots) Figure 1 Figure 3 Figure 4

Claims (2)

[Claims] (1) A shaft with an oil leak prevention feature characterized in that a nitrided layer is formed on the sliding portion with the oil seal, or a sleeve having a nitrided layer on the surface is fitted. (2) A patent for a sleeve having a nitrided layer on its surface, in which a nitrided layer with a hardness of Hv900 to Hv1600 is formed on a base material made of martensitic stainless steel in which fine carbides mainly composed of Cr are precipitated. A shaft according to claim 1.