JPS6036760Y2 - Rotor housing of rotary piston engine - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) This invention relates to the improvement of the rotor housing of a rotary piston engine, and is particularly applicable to the rotor housing of the so-called axial flow cooling system in which coolant flows through the engine in the axial direction. The purpose is to prevent the heat generated by the spark plug from having an adverse effect on the spark plug and the plug hole.

(Prior art) A polygonal rotor rotates planetarily in a casing consisting of a rotor housing with a multi-arc inner peripheral surface and side housings placed on both sides of the rotor housing, compressing the air-fuel mixture taken in from the intake port. In a rotary piston engine, which is then ignited by a spark plug, explodes, expands, and is discharged from an exhaust port, an axial coolant passage is provided in the rotor housing to cool the engine. A so-called axial flow cooling system in which the flow flows through in the axial direction is known.

The outline of the structure of the above-mentioned axial cooling type rotor housing will be explained with reference to FIG. Tightening is achieved by integrally forming a large number of bolt bosses 6 or a large number of ribs 7 that constitute the bolt hole 5.

Furthermore, the rotor housing 1 is provided with a plug hole 8.8 that penetrates through the inner wall 2 and outer wall 3 and into which a spark plug is installed, and the plug bosses 9, 9 connect the inner wall 2 and the outer wall 3. It also works.

The rotor housing 1 having the above structure is tightened by bolts inserted through the side housings arranged on both sides and the tightening bolt holes 5, thereby forming a casing and preventing deformation of the rotor housing 1 in the axial direction. It has become.

Generally, in this type of rotary piston engine,
Since each operating stroke is repeated in the same part of the casing, the rotary housing 1 has a locally heated part called a hot zone and a cooled part called a cold zone.

In particular, the inner wall 2 of the rotor housing 1 in the vicinity of the plug hole 8 is exposed to the high-temperature gas at the time of the explosion and also to the cold air-fuel mixture at the end of the compression stroke, so the temperature changes are extremely severe.

Therefore, large thermal stress is generated in the vicinity of the plug hole 8, causing permanent deformation and damage, and concentrated stress is generated around the plug hole 8, which is open in the inner wall portion 2, due to this thermal stress. There were problems such as cracks forming from hole 8.

In order to solve the above problem, a structure is developed in which an insert member made of a metal material having higher thermal conductivity than the base material forming the rotor housing is provided in the plug hole 8 to improve the cooling effect in the vicinity of the plug hole. This is known (for example, see Japanese Utility Model Publication No. 48-2884).

To explain this structure with reference to FIG. 2, when casting the rotor housing 1 whose base material is aluminum alloy,
A copper cylinder 10 passing through the inner wall 2 and the outer wall 3 with a gap between it and the core forming the coolant passage 4 at the position of the plug hole 8 is cast (FIG. 2A), and then the above-mentioned cylinder is A plug hole 8 is formed by drilling a hole in 10 with a drill, and then performing threading 8a and counterbore 8b (Fig. 2).

In this case, if the gap between the cylinder 10 for forming the core plug hole 8 that forms the coolant passage 4 is made smaller, the molten metal will not flow properly, so there is a limit to casting technology in order to make the gap smaller. be.

(Problems to be Solved by the Invention) In the conventional structure described above, although a part of the plug boss 9 is formed of the insert member 9a having good thermal conductivity, there is a large gap between the plug boss 9 and the coolant passage 4. Excess thickness of base material of target thickness 9
Due to the presence of b, the cooling effect of the plug hole 8 by the cooling liquid was not sufficiently improved.

Therefore, in the above structure, it may be possible to form the plug boss only with an insert member with good thermal conductivity, but in this case, the plug boss can pass through the gap between the insert member and the base material, which is caused by the difference in the coefficient of thermal expansion between the two members. There are problems such as the coolant leaking into the counterbore 8b of the plug hole 8 or into the working chamber, or the pressure gas in the working chamber entering the coolant passage 4.

(Means for solving the problem) This invention is based on the idea that a cylindrical insert member made of a metal material with higher thermal conductivity than the base material is inserted into the base material so that its inner peripheral surface is exposed in the coolant passage. A plug hole is formed in the base material that is cast and filled into the inner hole of the insert member, leaving excess thickness of the base material, and a plug boss is formed by the insert member and the excess thickness of the base metal. This is a rotor housing for a rotary piston engine.

(Embodiment) An embodiment of this invention will be explained with reference to FIG.
The insert member 11 is formed into a cylindrical shape having a waist, with the outer circumferential surface between the collar portions 11a and lla of the insert member 11 being sandwiched between the ends of the core or mold forming the coolant passage 4, and the insert member 11 is formed into a base material ( Aluminum alloy) is cast into (3rd
In Figure A), a hole is then drilled into the base material filled in the inner hole of the insert member 11 using a drill, and a plug hole 8 is formed by performing threading 8a and counterbore 8b.

In this case, the outer peripheral surface of the insert member 11 is connected to the coolant passage 4.
The plug boss 12 is formed by the insert member 11 and the extra thickness 12a of the base material on the inner peripheral surface thereof.

Since the entire inner portion 12a of the base material is formed by drilling after the rotor housing is cast, it can be thinned to a desired thickness.

Note that 13 in the opening of FIG. 3 is a base member made of iron plate provided on the inner wall portion 2, and the surface thereof is plated with chrome.

In this invention, cast iron is used as the base material in addition to the aluminum alloy of the above embodiment, and copper or a copper alloy is used as the metal material having higher thermal conductivity than the base material.

In the above embodiments, the insert member is provided with a flange, but it may be a simple cylindrical member with the flange removed.

However, the force provided by the flange portion is preferable because it facilitates positioning of the insert member during casting and further improves heat shrinkage in the vicinity of the plug hole.

(Effects of the invention) According to this invention, it is possible to reduce the thickness of the extra wall of the base material forming the plug boss, and as a result, the cooling effect of the cooling liquid near the plug hole is significantly improved.

As a result, cracks are prevented from forming in the inner wall portion of the rotor housing where the plug hole opens, and the temperature of the center electrode of the spark plug is lowered by cooling inside the plug hole, thereby preventing pre-ignition.

Further, according to this invention, the coolant does not leak from the coolant passage to the outer wall side, and the pressure inside the working chamber does not intrude into the coolant passage.

[Brief explanation of the drawing]

Fig. 1 is a vertically cut front view of a part of the rotor housing, Fig. 2 is a side view cut along line A-A in Fig. 1 explaining the order in which insert members are provided in the plug boss, and Fig. 3 is a cross-sectional view showing an embodiment of this invention. FIG. 2 is a cutaway side view similar to FIG. 2; 1: rotor housing, 4: coolant passage, 8 nib lug hole, 11: insert member, 11a: collar, 12 nib lug boss, 12a: extra wall portion.

Claims (1)

[Scope of Claim for Utility Model Registration] [1] A cylindrical insert member made of a metal material with higher thermal conductivity than the base material is cast into the base material so that its outer peripheral surface is exposed in the coolant passage, A plug hole is formed in the base material filled in the inner hole of the insert member, leaving excess thickness of the base material, and a plug boss is formed by the insert member and the excess thickness of the base metal. Rotor housing of rotary piston engine. [2] Utility model registration claim 1 where the base material is aluminum alloy and the insert member is copper or copper alloy
The rotor housing of the rotary piston engine described in . [3] The rotor housing for a rotary piston engine according to claim 1 or 2, wherein the insert member is a cylinder with flanges formed at both ends.