JPS5836161B2 - rotary piston engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotary piston engine, particularly a rotary piston engine that combines a side housing (including an intermediate housing in the case of a multi-rotor type) and an oil seal.

Conventionally, the side housing of a rotary piston engine is made of cast iron (FCH-2), and this cast iron surface is used for various seals attached to the rotor, such as oil seals,
The side seals, corner seals, and avex seals each slide at high speed.

Among these various seals, the oil seal requires the most severe customization between the side housing and the side housing.

This is because other seals are gas seals and are designed to make surface contact with the side housing, whereas oil seals are designed to make line contact with the side housing in order to scrape off oil. This is because it is configured to scratch the surface.

As shown in Fig. 1, a conventionally used oil seal 1 has a hard chrome plating 3 applied to the inner peripheral surface of a ring-shaped base material 2 made of high phosphorus and high boron cast iron. As a result, the contact width (lip width) t of the lip portion 4 of the seal increases, deteriorating the sealing function, that is, oil retention, and resulting in an increase in the amount of oil consumed by the engine.

In general, oil consumption is proportional to increasing rapidly as the lip width increases, so in order to prevent oil consumption from increasing, it is sufficient to prevent the lip width of the seal from increasing. Various attempts have been made to improve this.

As a successful example, it has been proposed that a high-hardness sintered chip containing carbide of 50 volumes or more is fused to the lip of an oil seal.

According to this product, as shown in Fig. 3, the custom-made wear curve shown by the sintered chip product (comparative example 2) is lower than the custom-made wear curve shown by the high-phosphorus, high-boron cast iron plated with chrome (comparative example 1). It can be seen that the wear resistance ratio is significantly improved.

The inventors were not satisfied with this result, and after researching an oil seal that showed better wear resistance, they found a specific oil seal that was made from steel, which had been thought to be bad, and was coated with chrome. It was discovered that when the side housing surfaces were combined, unexpectedly excellent wear resistance was exhibited, and the present invention was developed based on this knowledge.

The present invention uses Fe formed on the surface of a material made of iron-based material by nitrocarburizing treatment in a rotary piston engine.
- It has a C-N compound layer, the layer thickness of this compound layer is 1.0μ or more, and the surface roughness of the sliding surface part is at least 0.3
It is characterized by a combination of a side housing with a thickness of ~15μ and an oil seal that is retractably fitted into a ring groove provided on both sides of the rake, and whose lip is plated with hard chrome. It is something.

The method of manufacturing the side housing according to the present invention is to mechanically finish the necessary parts of a material made of ferrous material such as cast iron or cast steel to a predetermined dimensional accuracy by grinding, etc., and then perform gas nitrocarburizing or tuft-riding. A process in which a Fe-C-N compound layer is formed on the surface by nitrocarburizing treatment, and then at least the part of the compound layer that slides on the oil seal is polished to a predetermined surface roughness. It is manufactured through the process.

The side housing manufactured in this way has Fe-
It has a surface coating structure having a C--N compound layer and a diffusion layer underneath.

In particular, the layer thickness of the compound layer in the part that slides with the oil seal is 1
, 0μ or more and the surface roughness is within the range of 0.3 to 15μ.

Next, we will discuss the characteristics required of the side housing.

- Regarding wear resistance and lubricity, the side housing itself does not wear out or get damaged when it is rocked with oil seals, side seals, avex seals, and corner seals at high temperatures and high speeds. It must also be something that will not wear out.

As is well known, the compound layer formed by soft nitriding methods such as gas soft nitriding method and tuftride method is a Fe-C-N compound and has high hardness, but on the other hand, the surface shape is extremely uneven. If this is used as it is as a side housing, there is a drawback that the lip of the oil seal will wear out significantly when the engine is left idling for a long time.

This appears to be because the uneven surface is ground during low-speed rotation, and the ground compound particles are held within the grinding motion and function as grindstone grains.

However, the smaller the surface roughness, the better.

In other words, the inner surface of the side housing also serves as a moving mechanism between the combustion chamber wall surface and various seals, so if the surface roughness is too small, the oil film that should be on the moving mechanism will be burned away and there will be insufficient lubrication during shaking. This is because there is a risk that this may cause seizure or abnormal wear.

To address this problem, we have attempted to ensure oil retention, that is, lubrication, by leaving the fine irregularities that are inherent on the surface of the nitrocarburized layer.

Therefore, the surface roughness of the compound layer on the side housing surface must be of a level that satisfies both wear resistance and lubrication.

As a result of various experiments based on these requirements, the surface roughness was determined to be 0.3.
It has been found that it is necessary to be within the range of ~15μ.

If it is less than 0.3μ, oil retention on the surface is insufficient,
This is because sufficient lubricity cannot be obtained, and conversely, if it exceeds 15μ, the chrome plating of the oil seal will wear out and have a negative effect on cutting wear.

Further, the thickness of the compound layer must be at least 1 μm from the viewpoint of durability against abrasion.

That is, an automobile engine is required to be able to withstand 100,000 cycles, which is a rough guideline.

On the other hand, the oil seal's base is made of steel (carbon steel, alloy steel, etc.), and its inner circumferential surface is plated with hard chrome to a thickness of 0.1 to 2.
0 mm, and the sliding part of the oil seal is slightly inclined so that this chrome plated part contacts the side housing.

(See Figure 1) The side housing and oil seal described in detail above exhibit extremely excellent wear resistance as shown in the test examples described later.

This degree is much superior to that of a combination of the above-mentioned side housing and the above-mentioned oil seal in which the hard sintered tip is fused.

This simply means that conventional oil seals with fused sintered chips were superior, but the relationship of superiority is reversed when the side housing surface is nitrocarburized.

This is thought to be due to the fact that the nitrocarburized side housing and the chromium plating are particularly compatible with each other.

Wear Test It is a ring-shaped oil cylinder having a cross-sectional shape as shown in Fig. 1, an outer diameter of 130 mm, an inner diameter of 124 r/LrIL, and a height of 6.0 mm, and its base material 1 is made of carbon steel (S55CS2J).
IS), and chrome plating 2 is applied to the inner surface to a thickness of 0.15.
The test piece with a length of 10 mm was prepared by dividing the test piece.

On the other hand, a first test device shown in Fig. 2 was manufactured, and the rotating disk 3 was made of cast iron (FCH-2JI
S), the surface thereof was subjected to gas nitrocarburizing treatment (processing conditions may be within commonly used ranges), and the sliding surface was further polished to a surface roughness of 1 to 5 μm.

In the figure, 6 is the test piece described above, which is biased by a spring 7.

The test apparatus configured as described above was operated at a relative speed of 5.2 m/s of the sliding part and a load (pressing force by the spring 7) of 5.0 m/s.
The test piece was operated under conditions of 5 kg and no lubrication, and the amount of wear on the test piece was measured.

The results are shown in FIG. As comparative examples, two examples were prepared in the same way as the above test pieces and rotating disks: the oil seal was fused with the sintered chip described above, and the side housing was made of cast iron that had not been subjected to gas nitrocarburizing. The results of installation and testing are shown below.

In the figure, Comparative Example 1 is a high-phosphorus, high-boron cast iron with a chrome-plated oil seal and an untreated cast iron side housing, and Comparative Example 2 is a side housing that is the same as Comparative Example 1. Comparative Example 3 corresponds to a combination of a housing material and a sintered chip fused oil seal, and Comparative Example 3 corresponds to a combination of a sintered chip fused oil seal and a side housing subjected to gas nitrocarburizing.

As is clear from these results, it can be seen that the products of the examples of the present invention exhibit extremely excellent wear resistance.

In particular, chromium-plated oil seals, which traditionally tended to be unreliable due to lack of wear resistance, are extremely improved only when the mating material is gas nitrocarburized and finished to a specified surface roughness. I understand that.

The reason why wear resistance is improved so much is that mutual injection is particularly good.

As stated above, the combination of the oil seal and side housing in the present invention is practically excellent.
In driving tests using an actual engine, it has demonstrated sufficient durability for 200,000 miles of driving.

[Brief explanation of the drawing]

Figure 1 is a partially cutaway view showing the structure of the oil seal, Figure 2 is a schematic diagram of the wear test device, Figure 3 shows the results of the wear test, and Figure 4 is the one shown in this book. FIG. 3 shows a front view of a rotor equipped with an inventive oil seal. 1...Oil seal, 2...Base material, 3
...Chrome plating, 4...Riff part.

Claims (1)

[Claims] 1 In a rotary piston engine in which a rotor within a gap formed by a rotor housing and a side housing performs star-selecting rotation, Fe-C formed on the surface of a material made of iron-based material by nitrocarburizing treatment is used. - A side housing having an N-based compound layer, the thickness of this compound layer being 1.0μ or more, and a surface roughness of at least 0.3 to 15μ on the sliding surface, and grooves on both sides of the rotor. A rotary piston engine characterized by a rotary piston engine that is fitted in a ring groove so as to be freely retractable, and is combined with an oil seal whose base is made of steel and whose lip is plated with hard chrome.