JPH0647948B2 - Side housing of rotary piston engine and manufacturing method thereof - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a side housing of a rotary piston engine and a manufacturing method thereof.

(Prior Art) Currently, the side housing of a rotary piston engine is made of cast iron, and the rotor seal, that is, the sliding surface on which the side seal and the oil seal slide, is subjected to soft nitriding treatment to increase wear resistance. .

By the way, recently, due to demands such as the multi-rotor of a rotary piston engine, it has been desired that the side housing is made of a light metal material such as an aluminum alloy or a magnesium alloy. In such a case, it is necessary to treat the sliding surface on which the rotor seal slides so as to have wear resistance. There is a method of thermal spraying ceramics or ceramics (see Jpn.

(Problems to be solved by the invention) However, when a hard layer is formed on the sliding surface on which the seal of the rotor slides by thermal spraying, the bonding strength between the hard layer and the light metal forming the side housing is not sufficient. Causes the problem.

Further, a light metal, particularly an aluminum alloy generally used as a light metal, has extremely good heat conduction as compared with an iron-based metal, so that there is a problem that supercooling is likely to occur.

Therefore, a first object of the present invention is to firmly integrate a hard layer formed on a sliding surface on which a seal of a rotor slides into a side housing when the side housing is mainly composed of a light metal. It is an object of the present invention to provide a side housing of a rotary piston engine, which is capable of preventing overcooling.

A second object of the present invention is to provide a method for manufacturing a side housing of a rotary piston engine, which allows the above-mentioned side housing to be easily and inexpensively formed.

(Means and Actions for Solving Problems) In order to achieve the above-mentioned object, the side housing of the present invention has the following configuration. That is, at least a light metal is mainly used, the sliding surface on which the rotor seal slides is formed of a hard plating layer, and at least the inner surface of the cooling water passage is covered with an anodic oxide film.

With such a structure, the hard plating layer can be treated at a low temperature due to the characteristics of the plating and has sufficient bonding strength to light metals. Therefore, the hard plating layer is firmly integrated with the side housing. Can be converted. Further, since the inner surface of the cooling water passage is covered with the anodic oxide film having excellent throwing power and heat insulating properties, the transfer of heat to and from the cooling water flowing through this cooling water passage is suppressed, and the engine Supercooling will also be prevented.

In order to achieve the second object, the method of the present invention has the following configuration. That is, a step of masking a sliding surface on which the seal of the rotor slides, of the surface of the side housing body mainly composed of light metal, and the masked side housing body,
A step of anodizing at least the periphery of the masked surface and the inner surface of the cooling water channel; and a step of removing the masking and then performing a hard plating treatment on the exposed sliding surface. It is as a configuration.

With such a configuration, the portion to be plated can be made into a minimum necessary area range of the sliding surface on which the seal of the rotor slides due to the insulating function of the anodic oxide film, and the manufacturing cost can be reduced. You can hold it down. In particular, since the anodic oxide film used for ensuring heat insulation is used as it is as masking when plating only the desired portion, compared to when masking separately when plating. This is advantageous in terms of cost and omission of the manufacturing process. Further, since the portion to be masked during the anodic oxidation treatment may be performed on a flat surface such as a seal sliding surface, this masking work can be easily performed. Furthermore, since the anodic oxide film is much harder than light metal, when polishing with a grindstone to make the surface having the hard plating and the anodic oxide film a flat surface, the light metal is clogged with the grindstone. Without this, this polishing process can be performed easily and accurately.

Of course, since the anodic oxide film has good throwing power, it is possible to sufficiently cover the inner surface of the cooling water channel with the anodic oxide film, and also to cover the entire surface except the hard plating layer with this anodic oxide film. By doing so, it is possible to obtain not only supercooling prevention but also excellent corrosion resistance as the entire side housing.

Embodiments Embodiments of the present invention will be described below with reference to the accompanying drawings.

In FIG. 7, reference numeral 1 is a rotor housing, 2 is a rotor housed inside the rotor housing, and an inner peripheral surface 1 of the rotor housing 1 is shown.
a is a cocoon-shaped peritrochoid curve, while the rotor outer peripheral surface 2a is an inner envelope of this peritrochoid curve, and between the rotor housing 1 and the rotor 2, three working chambers 3, 4, 5 are defined. In FIG. 7, among the three working chambers 3, 4, 5, the working chamber 3 is in the exhaust stroke communicating with the exhaust port 6 formed in the rotor housing 1, and the working chamber 4 is the side housing. 7 shows the state in the intake stroke communicating with the intake port 8 opening to 7, and the case where the working chamber 5 is in the expansion stroke after ignition by the spark plug 9.

As is known, the rotor 2 is provided with an apex seal 11 at each top thereof, while a side face thereof is provided with a corner seal 11, an oil seal 12, and a side seal 13. The apex seal 11 slides on the inner peripheral surface 1a of the rotor housing 1, and the other seals 11, 12 and 13 slide on the side housing 7, respectively.

The side housing 7 according to the present invention is, in the embodiment, the first
As shown in FIG. 2 and FIG. 2, the side housing main body 21 made of a light alloy such as an aluminum alloy, and the inner side central portion of the side housing main body 21, ie, the nose seals 11, 12, 13
The entire surface of the side housing main body 21 including the iron-based metal plate 22 embedded in the sliding portion, the hard plating layer 23 applied to the exposed surface of the iron-based metal plate 22, and the inner surface of the cooling water passage 24. And the anodic oxide film 25 applied to the. The iron-based metal plate 22 is integrated with the side-housing main body 21 by being encased when the side-housing main body 21 is cast (high-pressure casting). The back surface is uneven. The iron-based metal plate 22 is a concept including a titanium alloy plate.

With the above configuration, the hardness of the hard plating layer 23 on which the seals 11, 12, 13 slide is sufficiently high, and the wear resistance of the side housing 7 is sufficiently ensured. Since the bonding strength of the plating to the light metal is sufficiently larger than the bonding strength when the metal or ceramic is sprayed on the light metal, peeling of the hard layer made of the hard plating layer 23 is prevented for a long period of time. Particularly, when the hard plating layer 23 is formed on the side housing body 21 via the iron-based metal plate 22 as in the embodiment, the bonding strength of the hard-plated layer 23 to the iron-based metal plate 22 is extremely strong. It is more preferable than the above.

In addition, the inner surface of the cooling water passage 24 has an anodized film 2 with excellent heat insulation.
Since it is covered with 5, the heat exchange with the cooling water flowing in the cooling water passage 24 is suppressed, and the supercooling of the engine is prevented. In particular, if the anodic oxide film 25 is formed on the entire surface of the side housing body 21 (excluding the hard plating layer 23 portion) as in the embodiment, it is more advantageous in preventing overcooling. The hard plating layer 23 and the anodic oxide film 25 around it are polished so that they are flush with each other.

Next, a method of manufacturing the above-mentioned side housing 7 will be described.

First, as shown in FIG. 3, the side housing body 21
Is subjected to high pressure casting so as to surround the iron-based metal plate 22.

Next, as shown in FIG. 4, after the exposed surface of the iron-based metal plate 22 is masked, the side housing body 21 is anodized, and the entire surface other than the masked iron-based metal plate 21 is anodized. The film 25 (hard alumite when the light metal forming the side housing body 21 is an aluminum alloy) is formed. Since the masking may be performed on the flat surface of the side housing body 21, the masking work can be easily performed.

Thereafter, as shown in FIG. 5, the masking is removed from the iron-based metal plate 22, and the exposed surface of the metal plate 22 is hard-plated to form a hard-plated layer 23. At this time, since the anodic oxide film 25 fulfills a masking function (insulating function) at the time of plating, it becomes unnecessary to separately carry out masking when the hard plating layer 23 is formed only at a desired position.

Finally, as shown in FIG. 6, the hard plating layer 23
The side housing 7 is completed by polishing the surface of the. During this polishing, since the anodic oxide film 25 is sufficiently harder than the light metal, that is, the side housing main body 21, clogging of the grindstone is prevented, and the adverse effect due to this clogging is prevented.

(Example) (1) A cast iron plate having a plate thickness of 4 mm is used as the iron-based metal plate 22,
After being set in the side housing mold, an aluminum alloy is pressure cast by a molten metal casting method to manufacture a side housing having a predetermined shape. After this, heat treatment (T-6 treatment) is performed and mechanical processing (rough processing) is performed.

Components of cast iron plate (wt%) Alloy cast iron: C3.5, Si2.1, Mn0.7, P0.1 or less, S0.
1 or less, Cr0.3, Cu0.7, balance Fe Aluminum alloy material: JIS standard AC4D alloy equivalent Molten metal casting method: Pressure 700 Kg / cm ² Core used: Zn core Heat treatment: T6 treatment 500 ° C x 3 hours (water cooling) → 180 ° C × 6 hours air cooling (2) The surface of the cast iron plate is masked with a commercially available acid-resistant fluorine-based masking paint and then anodized. After the treatment, the masking paint is removed.

Anodizing conditions Bath composition: 15 vol% sulfuric acid, Electrode (cathode) plate: Lead Electrolysis conditions: Current density 1.5 A / cm ² , bath temperature -5 ° C, electrolysis time 2.5 hours (anodic oxide layer thickness about 100 μ) (3) After the anodic oxidation treatment, in order to improve the corrosion resistance and the electric insulation, it is immersed in boiling water (using ion-exchanged water) for 30 minutes or more for sealing treatment. Since the anodic oxide film is porous, this sealing treatment is performed, but it is preferable that the thickness of the anodic oxide film is 50 μm or more in order to secure the insulating property.

(4) The surface of the cast iron (sliding surface) is plated with hard chrome using a normal Sargent type chrome plating bath.

Plating bath composition: Chromic anhydride 250 g /, Sulfuric acid 2.5 g / Plating conditions: Bath temperature 50 ° C, current density 50 A / cm ² , plating time 3 hours (plating thickness 70μ) At this time, formed on the aluminum surface by anodizing treatment The formed oxide layer (alumina: AlO ₃ ) plays a role of masking during plating. This inorganic oxide layer has electrical insulation and acid resistance. Then, due to the excellent throwing power peculiar to the anodizing treatment, the oxide film is uniformly formed on the entire surface including the bag structure portion of the side housing.

(5) Polish the sliding surface and machine parts to complete the process.

An engine test was conducted on the side housing 7 manufactured as described above under the following test conditions.

Engine specifications: Displacement 1300 cc (2 rotors), maximum output 145 ps Lubricating oil supply method: direct, separate combined type Lubricating oil supply ratio: direct / separation = 50/50 Operating cycle: 1500 rpm no-load operation 20 seconds, then After fully rotating the accelerator to 7,000 rpm and maintaining it for 1.25 minutes in a fully loaded state, the process of returning the accelerator to no load and reducing the rotational speed to 1500 rpm was set as one cycle, and this cycle was repeated up to 6000 cycles.

The results after passing through the above operation cycle are shown in the following table, and the result equal to or higher than that of the cast iron gas nitrocarburized product of the current specification was obtained. No peeling of the hard plating 23 was observed.

(Effect of the Invention) As is apparent from the above description, the side housing according to the present invention is mainly made of a light metal to achieve a significant reduction in weight as a whole, and is excellent in the bonding strength of the hard layer on which the rotor seal slides. In addition, it is possible to prevent supercooling.

Further, according to the method of the present invention, the side housing as described above can be easily and inexpensively manufactured.

[Brief description of drawings]

FIG. 1 is a front view of a side housing of the present invention. 2 is a sectional view taken along the line II-II in FIG. 3 to 6 are front views showing the manufacturing process of the side housing of the present invention. FIG. 7 is a front sectional view of a rotary piston engine. 7: Side housing 21: Side housing body made of light metal 23: Hard plating layer 24: Cooling water passage 25: Anodized film

Claims (2)

[Claims] 1. A main component is at least a light metal,
A side housing of a rotary piston engine, wherein a sliding surface on which a seal of a rotor slides is formed of a hard plating layer, and at least an inner surface of a cooling water passage is covered with an anodic oxide film. 2. A step of masking a sliding surface on which a seal of a rotor slides, of the surface of a side housing body mainly composed of at least light metal, and the masked side housing body,
A step of anodizing at least the periphery of the masked surface and the inner surface of the cooling water channel; and a step of removing the masking and then subjecting the exposed sliding surface to a hard plating treatment. A method for manufacturing a side housing of a rotary piston engine, which is characterized in that