JPH0730713B2 - Exhaust port structure of rotary piston engine - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust port structure for a rotary piston engine, and more particularly to an exhaust port structure having an exhaust port insert inserted therein.

(Prior Art) Exhaust of a rotary piston engine in which a cylindrical exhaust port insert is inserted into an exhaust port having an opening on the trochoid inner peripheral surface of a rotor housing, leaving a gap for secondary air supply on the outer periphery thereof. The port structure is actually 60-
It is disclosed in Japanese Patent No. 108727. According to the above configuration, since there is a gap between the outer circumference of the exhaust port insert and the inner circumference of the exhaust port, the exhaust gas passing through the exhaust port insert can be separated from the aluminum alloy housing, which is a separate example. Is reduced, the temperature of the exhaust gas passing through the exhaust port is prevented from lowering, and the reaction in the exhaust gas purification device provided in the exhaust pipe is promoted. Also, oxygen is replenished by the secondary air introduced into the gap, and the reaction in the exhaust gas purification device is promoted. On the other hand, in a rotary piston engine, during the overlap period in which the working chamber in the intake stroke and the working chamber in the exhaust stroke communicate with each other through the opening in the exhaust port, the exhaust gas from the working chamber in the exhaust stroke opens in the opening in the exhaust port. There is a phenomenon in which the idle rotation becomes unstable due to a decrease in ignition performance by flowing into the working chamber through the intake stroke.
By letting the next air flow into the working chamber in the intake stroke from the above-mentioned gap, the exhaust gas mixed in the intake air is diluted and pollution by the exhaust gas of the intake air is reduced, and normal combustion is maintained in the subsequent combustion stroke. It is known to be done.

However, when the secondary air is introduced into the gap formed on the outer circumference of the exhaust port insert, the secondary air is introduced into the gap because of the opening of the cooling water passage, the bolt insertion hole and the like around the exhaust port. The air passage for supplying the air must be provided so as to penetrate from the lower part of the rotor housing to reach the lower part of the exhaust port insert, and the opening in the gap of the secondary air supply passage is formed on the inner circumference of the trochoid. It had to be formed at a position away from the surface. Therefore, the secondary air is ejected only slightly into the working chamber in the intake stroke, and there is a problem that the exhaust gas dilution effect in the intake air by the secondary air in the overlap period as described above cannot be sufficiently obtained.

(Object of the Invention) In view of the above-mentioned circumstances, the present invention can sufficiently dilute the exhaust gas flowing into the working chamber in the intake stroke in the overlap period by the secondary air, and further advances the exhaust gas. An object of the present invention is to provide an exhaust port structure for a rotary piston engine, which can also prevent the inflow by a secondary air flow.

(Constitution of the Invention) Therefore, according to the present invention, a cylindrical exhaust port insert is inserted into the exhaust port having an opening on the trochoid inner peripheral surface of the rotor housing, leaving a gap for secondary air supply on the outer periphery thereof. In the exhaust port structure of the rotary piston engine, a secondary air supply passage is provided inside the exhaust port insert, and the secondary air supply passage reaches the above-mentioned gap through the air passage formed in the rotor housing. An inlet for introducing secondary air into the secondary air supply passage in the vicinity of the opening of the air passage facing the gap, and an opening of an exhaust port from the secondary air supply passage to the secondary air. The above-mentioned object is achieved by forming a lead-out port leading out to the leading side with respect to the rotation of the rotor, that is, on the minor axis side of the trochoid.

(Effects of the Invention) According to the present invention, 2 is provided inside the exhaust port insert.
A secondary air supply passage is provided, and an introduction port for introducing secondary air into the secondary air supply passage is provided in the vicinity of the opening of the air passage formed in the rotor housing facing the gap. Therefore, the secondary air supplied from the air passage is efficiently introduced into the secondary air supply passage, and the secondary air outlet of the secondary air supply passage outputs the secondary air. Since it is provided so as to lead to the leading end of the opening of the exhaust port, it flows from the working chamber side in the exhaust stroke to the working chamber side in the intake stroke through the opening of the exhaust port during the intake / exhaust overlap period. The exhaust gas that is generated is reliably diluted by the secondary air that is ejected from the secondary air outlet formed on the leading side of the opening of the exhaust port, and this secondary air flow forms an air curtain, so the intake stroke It is also possible to shut off the flow of exhaust gas into certain working chamber side.

(Examples) Examples of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of a rotary piston engine including an exhaust port structure of the present invention. The rotor 2 has a trochoid inner peripheral surface 1a, and the rotor 2 performing planetary rotational motion along the inner peripheral surface 1a has three working chambers 3a. An exhaust port 4 having an opening 4a on the trochoid inner peripheral surface 1a is provided in the rotor housing 1 in which is formed. Also rotor housing 1
An intake port 6 is opened in one of the side housings 5 which are attached so as to sandwich.

As shown in FIGS. 2 and 3, a cylindrical exhaust port insert 7 is inserted into the exhaust port 4 with a gap 8 left on the outer periphery thereof. The exhaust port insert 7
The central portion has a double structure including an outer cylinder 7a and an inner cylinder 7b, and an annular secondary air supply passage 9 is formed by the gap between the outer cylinder 7a and the inner cylinder 7b. The end of the secondary air supply passage 9 on the side opposite to the exhaust port opening 4a side is closed, and the end on the exhaust port opening 4a side is also the leading side with respect to rotor rotation, that is, inside the rotor housing 1. It is closed except for the minor axis side of the trochoidal curve forming the peripheral surface 1a. Then, only the outer cylinder 7a and the inner cylinder 7b on the leading side are extended toward the leading side of the exhaust port opening 4a to form the nozzle 10, and by this nozzle 10, secondary air is supplied from the secondary air supply passage 9. A secondary air outlet 11 for ejecting the air into the working chamber 3 is formed.

On the other hand, in the rotor housing 1, the secondary air supply passage 9 formed by the outer cylinder 7a and the inner cylinder 7b of the exhaust port insert 7 and the gap 8 formed outside the passage 9 are separated from the air pump. An air passage 12 for supplying secondary air is provided, and this air passage 12 opens into the gap 8 at the opening 12a. Then, in the outer cylinder 7a of the exhaust port insert 7, the secondary air is introduced into the passage 9 in the vicinity of the opening 12a, preferably at a position facing the opening 12a, as shown in FIG. A secondary air inlet 13 is provided for introducing. Therefore, the secondary air supplied from the air passage 12 flows into the gap 8 through the opening 12a, enters the passage 9 from the inlet 13, and is ejected from the nozzle 10.

The above is an example of the structure of the exhaust port structure according to the present invention. Next, the operation will be described. The combustion gas explosively expanded by the ignition of the spark plug 14 causes the rotor 2 to rotate in the direction of arrow 15. The rotor 2 rotates to the position shown in Fig. 2 and the working chamber 3A begins to enter the exhaust stroke, while the working chamber 3B on the leading side of the working chamber 3A begins to enter the intake stroke,
This is an overlap period in which the working chambers 3A and 3B communicate with each other through the exhaust port opening 4a. Therefore, the exhaust gas in the working chamber 3A is exhausted through the exhaust port 4, and a part of this exhaust gas flows into the working chamber 3B on the leading side from the exhaust port opening 4a and is mixed into the intake air. However, it was efficiently introduced into the secondary air supply passage 9 from the secondary air introduction port 13 formed in the outer cylinder of the exhaust port insert 7 near the opening 12a of the air passage 12 facing the gap 8. Since the secondary air is ejected from the nozzle 10 as shown by the arrow 16 and flows into the working chamber 3B together with the exhaust gas, the exhaust gas is diluted and the pollution degree of the intake air is reduced. Moreover, since the secondary air flow ejected from the nozzle 10 forms an air curtain to block the inflow of exhaust gas into the working chamber 3B, the degree of pollution of intake air is further reduced. Therefore, the working chamber 3B
The explosion stroke at is performed with intake air in a state close to normal, and it is possible to avoid a decrease in engine output.

On the other hand, during the exhaust stroke, the secondary air ejected from the nozzle 10 and the secondary air flowing out of the gap 8 flow out from the exhaust port 4 together with the exhaust gas, and the exhaust gas purification installed in the exhaust pipe downstream of the exhaust port 4 is performed. Introduced into the device. The exhaust port insert 7 has a gap 8 for supplying secondary air to the exhaust port 4.
The exhaust port insert 7 does not come into direct contact with the cooled rotor housing 1 since it has been inserted. Therefore, the temperature of the exhaust gas flowing in the exhaust port insert 7 can be maintained and the above-mentioned 2
The secondary air replenishes the combustion oxygen in the purifier to promote the purifying reaction.

[Brief description of drawings]

FIG. 1 is a sectional view of a rotary piston engine to which the exhaust port structure of the present invention is applied, FIG. 2 is an enlarged sectional view of a main portion thereof, and FIG. 3 is a sectional view taken along line III-III of FIG. FIG. 4 is a front view of the exhaust port opening. 1 …… Rotor housing, 4 …… Exhaust port 7 …… Exhaust port insert 7a …… Outer cylinder, 7b …… Inner cylinder 8 …… Gap 9 …… Secondary air supply passage, 10 …… Nozzle 11 …… 2 Secondary air outlet, 12 …… Air passage 13 …… Secondary air inlet

Claims (1)

[Claims] 1. A rotary piston engine in which a cylindrical exhaust port insert is inserted into an exhaust port having an opening on the trochoid inner peripheral surface of a rotor housing with a gap for secondary air supply left in the outer periphery thereof. In the exhaust port structure, a secondary air supply passage is provided inside the exhaust port insert, and the secondary air supply passage reaches the gap through an air passage formed in the rotor housing.
An inlet for guiding the secondary air into the secondary air supply passage in the vicinity of the opening of the air passage facing the gap, and an opening of the exhaust port for introducing the secondary air from the secondary air supply passage. An exhaust port structure of a rotary piston engine, characterized in that a lead-out port leading to the leading side of the is formed.