JPS62258120A - Side housing for rotary piston engine - Google Patents

Abstract

PURPOSE:To attempt improvement of wear resistance and burning resistance by providing a number of oil retaining recesses encircled by chilled layer dispersedly on a sliding surface other than the oil seal sliding surface of a side housing. CONSTITUTION:In a casing consisting of a rotor housing with a trochoid inner circumferential surface and a pair of a right and a left side housing 7 provided at both sides of said housing, the sliding surface 7a of the side housing 7 is formed cut of a cast iron plate 7b so as to be a composite casting product where said cast iron plate is internally chilled with an aluminum metal. And a chilled layer 9 is dispersedly formed on an oil seal sliding surface (c) in the outside of the sliding surface made of the cast iron plate 7b, and furthermore oil retaining recesses 11, the bottom of which is encircled by a chiiled layer 10, are dispersedly formed on the outer sliding surface (d) in the outside of said sliding surface (c). Owing to this constitution, lubricant is retained in the recesses 10 thereby improving lubricity against sealing members fitted on a rotor 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the structure of a side housing that forms the casing of a rotary piston engine together with a rotor housing, and particularly to the structure of its sliding surface.

[Prior Art] Conventionally, in order to meet the demand for weight reduction of automobiles, attempts have been made to make the side housing, which constitutes a part of the casing, of an aluminum alloy instead of cast iron in a rotary piston engine. However, since the sliding surface of the rotor with the side seal is subject to severe wear,
It has been proposed to use a cast iron plate for the seal sliding surface and to cast it in an aluminum alloy to create a composite seal.

However, even in this case, sufficient wear resistance is still not obtained, so especially on the sliding surface outside the outer envelope of the oil seal sliding trajectory where oil lubrication is insufficient.
The quench-hardened layer (
A side housing has been proposed in which the wear resistance is improved by forming a chill layer (see Japanese Patent Publication No. I6-20202). However, even with such a structure, the current situation is that sufficient wear resistance has not yet been achieved.

On the other hand, conventionally used cast iron side housings are treated with gas nitrocarburizing to improve their wear resistance, and the gas nitrocarburizing method is also applied to composite side housings such as those described above. It is possible to apply this method.

However, it is impossible to perform gas nitrocarburizing treatment after casting a cast iron plate with aluminum alloy because the treatment temperature is too high. Furthermore, even if the cast iron plate is subjected to gas soft nitriding treatment before casting, the nitrided layer and diffusion layer (approximately 30μ) will be removed when the cast iron plate is processed after casting, making it impractical for practical use. It is possible.

[Object of the Invention] An object of the present invention is to provide a lightweight side housing for a rotary piston engine that has excellent wear resistance and seizure resistance.

[Structure of the Invention] For this reason, the present invention provides a side housing for a rotary piston engine, in which a large number of oil holding recesses surrounded by a chill layer are distributed and formed on the sliding surface outside the sliding locus of the oil seal. This is a basic feature.

Such an oil retaining recess can be formed, for example, by irradiating a cast iron plate cast with an aluminum alloy with a laser beam.

[Effects of the Invention] In the structure of the present invention, lubricating oil is supplied into the working chamber in a large number of four oil holding parts, and the lubricity for the sole member piped in the rotor is improved, and the structure is surrounded by a chill layer. As a result, the wear resistance is improved, and it is possible to provide a lightweight side housing that has overall wear resistance and seizure resistance superior to, but not inferior to, conventional cast iron side housings.

[Example] Hereinafter, an example of the present invention will be specifically described with reference to the accompanying drawings.

As shown in FIG. 1, a casing 2 in which a rotor l makes planetary rotational motion includes a rotor housing 3 defining a trochoid inner circumferential surface 3a, a side seal fitted to a side surface Is of the rotor 1, and a Specifically, it is basically constituted by a side seal 4 and a side housing 7 that forms a sliding surface 7a for the outer and inner oil seals 5.6. The rotor housing 3 has a trochoid inner peripheral surface 3a of C
It is formed by casting a trochoidal steel plate 3c formed of an r-Mo alloy plating layer 3b with an aluminum alloy motherboard 13d.

In addition, the side housing 7 has a sliding surface 7a formed by a cast iron plate 7b.
The cast iron plate 7b is cast into an aluminum base material 7c to form a composite cast product.

The surface of the cast iron plate 7b is subjected to two types of treatments as described below.

That is, as shown in FIG. 2, the sliding surface 7a formed by the cast iron plate 7b has an outer envelope (circle) a of the sliding trajectory of the outer oil seal 5 and an inner envelope of the sliding trajectory of the inner oil seal 6. Oil seal sliding surface C enclosed between line (circle) II
and an outer sliding surface d outside the oil seal sliding surface C, and each sliding surface c, d is subjected to different types of treatment.

Incidentally, as shown in the cross-sectional structure in FIG. 3, the cast iron plate 7b
is actually a rectangular closed cross section 7b' and this closed cross section! A pair of side plates 7b'' and 7b'' on both sides supported by 7b'
It is formed as a cast product with a framework structure consisting of.

The oil seal sliding surface C has a circle S in FIG.

As shown enlarged in FIG. 1, the chill layer 9 is dispersed and formed, while the remaining sliding surface d has a circle S in FIG.

As shown in an enlarged view, oil holding recesses 11 whose bottoms are surrounded by chill layers 10 are formed in a dispersed manner.

To explain more specifically, first, the cast iron plate composite aluminum side housing has a thickness of about 411 mm as shown in the cross section in Figure 3.
The cast iron plate 7b of II11 is set in a mold for an aluminum side housing, and is pressure cast using molten aluminum alloy, subjected to a predetermined heat treatment, and then roughly processed to form a side housing.

The composition of the cast iron plate is C3.5vt%, Si 2.1vt
%, Mn 0.7wt%, P O, 1wt% or less, S
o, 1vt% or less, Cr O, 3wt%, Cu O, 7
wt%, balance of Fe. Furthermore, the composition of the aluminum alloy used is JIS standard AC4D. In addition,
A Zn core was used as the core, a molten metal forging method was used as the pressure casting method, and the material was pressure cast with a pressure cuff of 00 kg/cm.
child. In addition, the heat treatment conditions for the aluminum side housing are in accordance with the so-called T6 treatment, which is 500℃ and 3.
After being held for a period of time, it is water-cooled and hardened, then held at 180°C for 6 hours, and then air-cooled to perform a tempering treatment.

Next, surface treatment of the seal sliding surface by laser will be explained.

(a) Oil seal sliding part A laser device with an output of 100 W was used, and Ar gas was used as the assist gas. The gas pressure of the assist gas is approximately 0.5 kg/cm' for the oil seal sliding portion C, and the chilling rate is approximately 70%.

(b) Outside the oil seal sliding trajectory In the region d outside the oil seal sliding trajectory, increase the gas pressure of the unstuck gas to a gas pressure in the range of 1.0 to 3.0 Kg/Cm, and use a 40 Hz AC laser beam. Chilling rate 50%
Laser irradiation is performed so that

The hole diameter of the oil retaining recess to be formed is preferably 80 to 120 microns. The hole diameter can be controlled to a desired value by adjusting the assist gas pressure. If the hole diameter is 80μ or less, the amount of oil retained is small and the effect of improving wear resistance is small. If the hole diameter is 120 μm or more, combustion gas may blow through from the side seal, which is not preferable. In addition, each chill layer 1
It is preferable that the large area ratio of the oil retaining recesses to 0 is about 15%.

(c) Bench test As described above, the del layer 9 is formed in the sliding part C of the oil seal, and the oil holding recess surrounded by the del layer 10 is formed in the seal sliding part d outside the oil seal sliding part. A rotary piston engine was constructed using the side housing 7 formed with 11, and a bench test was conducted on the rotary piston engine.

*Test conditions (+) Engine used: turbocharged exhaust ff 11300cc, output horsepower 200PS engine (2) Operating conditions No-load operation at 1500 rpm for 20 seconds, then full-load operation at 700 rpm with the accelerator fully open for 75 seconds. After that, the process of releasing the accelerator, shifting to no-load operation, and lowering the rotation speed to 150 rpm was defined as one cycle, and this process was repeated for 6000 cycles.

(3) Lubrication method *Lubricating oil supply method A combination of direct lubrication into the rotor housing and lubrication into the intake passage was used.

*Refueling ratio Direct and indirect refueling amounts were set at equal ratios, that is, 50% each.

(4) Test results As a result of the above test operation, the amount of lip wear on the oil seal, the amount of wear on the side seals, and the stepped wear in the hot zone on the short axis side of the trochoid on the sliding surface of the side seals (shown as e in Figure 2) part) was measured. The measurement results are shown in the table below.As an oil seal material,
C3.7wt%.

Si 2.5wt%, Mn 0.7wt%, PO,
4wt%.

So, 12wt% or less, B 0.05wt%, Fe
The sealing surface of the remaining alloyed cast iron was chrome-plated. In addition, as a side seal, Fe-3%C
Use one made of sintered alloy.

As is clear from the above test results, the aluminum alloy side housing according to the present invention exhibits wear resistance equivalent to that of the cast iron side housing that has been subjected to gas nitrocarburizing treatment, which has been used in practical use. It turned out that there was no problem.

[Brief explanation of drawings]

FIG. 1 is a partial sectional view of a rotary piston engine according to an embodiment of the present invention, FIG. 2 is a front view of a side housing, and FIG. 3 is a sectional view taken along line A--A in FIG. 4...Side seal, 5.6...Oil seal, 7
...Side housing, 7b...Cast iron plate, 9,10
...Chill layer, 11...oil holding recess. 2nd t! 1 *3g] A

Claims (1)

[Claims] (1) On the sliding surface of the side housing of the rotary piston engine that makes sliding contact with the seal member attached to the rotor, an oil holding recess surrounded by a chill layer is provided on the sliding surface outside the oil seal sliding range of the side housing. A side housing for a rotary piston engine characterized by a large number of distributed piston housings.