JPH0341651B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an exhaust port structure for a rotary piston engine, in which an exhaust port is opened on the inner peripheral surface of a rotor housing having a trochoidal inner peripheral surface.

(Prior Art) A conventional rotary piston engine includes a rotor housing having a trochoidal inner circumferential surface in which a rotor is rotatably housed, and side housings attached to both sides of the rotor housing. together to form a rotor chamber. The rotor chamber has an apex seal portion between the rotor housing and the inner circumferential surface of the rotor housing at the corner vertices of the regular polygonal rotor, thereby defining a plurality of working chambers. The housing is formed with one or more intake ports and one exhaust port opening into the working chamber. The exhaust port of a conventional rotary piston engine is
Only one approximately oval hole having a long axis in the direction of the rotor's rotational axis is formed on the inner peripheral surface of the trochoid of the rotor housing, and this port is opened when the apex seal portion of the rotor passes through. It's becoming like that. Since this exhaust port has a long axis in the direction of the rotational axis of the rotor, the opening area of the exhaust port increases rapidly when the apex seal portion passes through the exhaust port. For this reason, a problem arises in that a large amount of exhaust gas concentrates at the exhaust port, creating a turbulent flow and rapidly expanding, producing high exhaust noise. In order to solve this problem, a so-called honeycomb structure has been proposed, in which the exhaust port is composed of a set of three circular ports, two on the leading side and one on the trailing side. -Refer to Publication No. 148621). Although this structure is effective to some extent in reducing exhaust noise, it has the drawback of increasing exhaust passage resistance.

(Objective of the present invention) The present invention provides a rotary piston engine having an exhaust port opened in a rotor housing.
Another object of the present invention is to provide an exhaust port structure that can reduce engine exhaust noise by suppressing rapid expansion of exhaust gas.

(Configuration of the present invention) In order to achieve the above object, the present invention is configured as follows. That is, the present invention defines an exhaust port opened on the inner peripheral surface of the rotor housing in the circumferential direction of the rotor housing, and a horizontal partition plate that extends in the flow direction of the exhaust gas, and a cylindrical outer cylinder that encompasses the horizontal partition plate. In an exhaust port structure for a rotary piston engine, the exhaust port structure for a rotary piston engine includes a port insert inserted in the exhaust flow direction into an exhaust passage portion formed in a rotor housing, in which a cylindrical outer cylinder of the port insert has an upstream side in the exhaust flow direction. The present invention is characterized in that a partition plate is provided on the side so as to cover the trailing side of the central portion of the port in the rotor rotational direction. According to the present invention, the exhaust passage is partitioned by the partition plate in the circumferential direction of the rotor housing, that is, in the rotational direction of the rotor, and in the extending direction of the partition plate, that is, in the longitudinal direction of the exhaust port. A screen plate extending perpendicularly is erected to cover the trailing side of the central portion of the port. Therefore, due to the rotation of the rotor, the rate at which the opening area of the exhaust port expands is substantially relatively slow, and the exhaust port is gradually opened.

(Effects of the present invention) According to the present invention, the above-described structure suppresses the opening speed of the exhaust port to a relatively low level, thereby alleviating the concentration of exhaust gas on the exhaust port, and the partition plate The presence of the exhaust gas prevents turbulence of the exhaust flow and rapid expansion of the exhaust gas. Therefore, exhaust noise can be effectively reduced.

(Embodiment) FIG. 1 shows a side port intake type rotary piston engine Z having an exhaust port structure according to an embodiment of the present invention. This rotary piston engine Z includes a rotor housing 1 having a trochoidal inner circumferential surface 4 and a pair of side housings 2 that seal both sides of the rotor housing 1, thereby forming a rotor chamber 10 therein. A substantially triangular rotor 3 is disposed inside the rotor chamber 10, and the rotor 3 is provided with an apex portion 30 having an apex seal that makes sliding contact with the inner circumferential surface 4 of the rotor housing 1. . As a result, working chambers 27a, 27b, and 27c are formed by the rotor housing 1 and the side surface of the rotor 3, respectively. The rotor 3 is supported by an eccentric shaft 5 and rotates in the direction indicated by the arrow in FIG. As the rotor 3 rotates, the volumes of the working chambers 27a, 27b, and 27c change periodically, thereby forming intake, compression, explosion, and exhaust strokes.
In FIG. 1, the state shown in the working chamber 27a is at the end of the explosion stroke and at the beginning of the exhaust stroke.
The working chamber 27b is in the intake stroke, and the working chamber 27c is in the compression stroke. The side housing 2 is provided with an intake port 6 that opens into the working chamber 27b during the intake stroke, and is adapted to introduce the air-fuel mixture into the working chamber 27b. The rotor housing 1 is provided with an exhaust port 7.
During the exhaust stroke, combustion gas is exhausted from the working chamber 27a.

Referring to FIG. 2, the exhaust port 7 includes one exhaust passage section or through hole 9 provided in the rotor housing 1, and the through hole 9 is connected to the rotor chamber through a lip 7a. 10 and penetrates through the rotor housing 1 in the thickness direction. The through hole 9 has a seat hole portion 9a facing inward from the rotor housing outer surface 1b,
It is composed of an inclined hole portion 9b extending further inward from the seat hole portion 9a, and a parallel hole portion 9c closest to the inner circumferential surface 4. Referring to FIG. 4, the mouth edge 7a has a rectangular shape with curved corners. The parallel hole portion 9c of the through hole 9 is the mouth edge portion 7
It has almost the same shape as a. Slanted hole part 9
At its inner end, that is, on the rotor chamber 10 side, the width of the rotor 3 in the direction of the rotation axis is slightly larger than the mouth edge 7a, and the length in the direction perpendicular to it is wider than the mouth edge 7a. As a result, a stepped portion S1 is formed on the trailing side and a stepped portion S2 is formed on the leading side. The slanted hole portion 9b is expanded outward on its leading side, so that its cross-sectional area increases outwardly.
The seat hole portion 9a is larger in both width and length than the outer end of the slanted hole portion 9b.
A step S3 is formed around the periphery. As shown in FIG. 2, a port insert 8 is adapted to be inserted into the through hole 9. Referring to FIG. 3, the port insert 8 includes a flange 11 that can be seated in a step S3 formed between a seat hole portion 9a and an inclined hole portion 9b. This port insert 8 is formed with a cylindrical outer cylinder, that is, an inclined cylinder part 12 extending from a collar part 11. The inclined cylinder portion 12 has a shape corresponding to the inclined hole portion 9b of the through hole 9. In this case, the inclined cylinder part 1
2 is configured such that a clearance G exists between it and the inclined hole portion 9b. Inside the port insert 8, there is provided a horizontal partition plate 16 that extends in the width direction of the insert, that is, in the horizontal direction. (exhaust passage) and a trailing side exhaust passage 21. The port insert 8 further includes a pair of vertical partition plates 17 that divide the trailing side exhaust passage 21 and extend in the vertical direction, that is, in a direction perpendicular to the direction in which the horizontal partition plate 16 extends.
As a result, the trailing side exhaust passage 21 has three
two subdivisions, namely, the second exhaust branch passage 22, the third
It is divided into an exhaust branch passage 23 and a fourth exhaust branch passage 24. The fourth exhaust branch passage 24 is formed between the two vertical partition plates 17, and the second and third exhaust branch passages 22 and 23 are formed at opposing positions on both sides of the fourth exhaust branch passage 24. Ru. The horizontal partition plate 16 and the vertical partition plate 17 extend outward from the inner end of the collar portion 11, that is, in the exhaust gas outflow direction, and extend inwardly along the inclined cylinder portion 12.
2 protrudes from the inner end and reaches the mouth edge 7a of the through hole 9. The tips 16a and 17a are
It reaches a position extremely close to the inner circumferential surface 4 of the rotor housing 1. The trailing side of the inclined cylindrical portion 12 extends inward from the tip 12a, that is, from the inner circumferential surface 4.
A screen plate 15 is formed that extends to the side and is bent at its tip toward the leading side, and covers a part between the pair of vertical partition plates 17. This limits the entrance area of the fourth exhaust passage 24. Therefore, the trailing side open end 24a of the fourth exhaust branch passage 24 is the same as the trailing side open end 22a of the second and third exhaust branch passages 22, 23,
It is located closer to the leading side than 23a by the length of the screen plate 15 in the circumferential direction of the rotor housing.

Next, the operation of the rotary piston engine Z of the illustrated embodiment will be explained. When the engine Z is operated, the rotor 3 slides the apex portions 30 attached to the three ridges onto the trochoid inner circumferential surface 4. The rotor 3 rotates planetarily around the eccentric shaft 5, and during one rotation of the rotor 3, intake air is sucked into the working chamber from the intake port 6, pressurized, and then combusted and exploded, and the combustion gas (exhaust gas) is sent to the exhaust port 7. discharge from.

Incidentally, as the rotor 3 rotates, the apex portion 30 passes through the exhaust port 7 from the trailing side to the leading side, and the exhaust port 7 is connected to the trailing side working chamber of the apex portion 30 (in FIGS. 1 and 2). 27a), the high pressure and high temperature exhaust gas in the trailing side working chamber 27a is discharged to the outside from the opened exhaust port 7 through the exhaust passage.

In this case, in this embodiment, the exhaust port 7
Leading side exhaust passage (first exhaust branch passage) 2
0 and a trailing side exhaust passage 21, and furthermore, this trailing side exhaust passage 21
is divided into three parts in the width direction of the rotor housing 1 to form second, third, and fourth exhaust branch passages 22, 23, and 24, so even if the exhaust gas pressure is particularly high (exhaust energy is large) immediately after opening, , the exhaust gas passes through the second, third, and fourth exhaust branch passages 22, 2, each having a small volume.
3 and 24, the rapid expansion of the exhaust gas is prevented and the exhaust energy of the exhaust gas is dispersed, and the horizontal partition plate 16 and the vertical partition plate 17 are used as a type of rectifying plate, The exhaust gas flow is rectified. Therefore,
There is less vibration noise and the exhaust noise of the engine Z is reduced.

In particular, in this embodiment, immediately after the opening of the exhaust port 7, each exhaust branch passage 22, 23, 24
The fourth exhaust branch passage 2 has a rectangular opening and whose opening area increases rapidly as the rotor 3 rotates.
The opening edge on the trailing side of No. 4 is closed with a screen plate 15, and the opening area immediately after opening is small.
Exhaust gas is discharged only from the third exhaust branch passages 22 and 23. Since the second and third exhaust passages 22 and 23 are shaped so that the opening area gradually increases as the rotor 3 rotates, the amount of exhaust gas released suddenly increases immediately after opening. Since the increase is suppressed, turbulence of the exhaust gas flow and rapid expansion of the exhaust gas are further suppressed, and the exhaust noise of the engine Z is further reduced.

Note that this exhaust port 7 has an exhaust passage partitioned off by a thin horizontal partition plate 16 and a vertical partition plate 17, and especially on the trailing side.
Because it has a unique structure, the passage area decreases less than that of the conventional honeycomb port type exhaust port structure, and therefore the exhaust port 7
When the exhaust gas is fully opened, a sufficient passage area can be secured, and problems such as a decrease in engine output due to an increase in exhaust resistance can be prevented from occurring.

The relationship between the noise reduction effect and the structure of the screen board 15 will be described in detail.

In this case, as shown in FIG. 2A, a tangent to the surface forming the working chamber 27a at the trailing side end of the exhaust port 7 and a hole portion at the trailing side of the inclined hole portion 9b of the exhaust port 7. A straight line drawn along the inner surface of 9b toward the working chamber l ₁
The angle θ ₂ formed by the tangent at the intersection of the straight line drawn along the top surface of the screen plate 15 in the direction of the working chamber _27a and the surface forming the working chamber 27b and the straight line l ₁ , the angle between the surface of the screen plate 15 on the working chamber 27a side and the above straight line _l1 , that is, the screen plate inclination angle θ,
Further, a distance A between the surface of the screen plate 15 on the working chamber 27a side and a surface forming the working chamber 27a, and a distance B from the trailing side of the exhaust port 7 to the top of the screen plate 15 are defined, respectively. The angle θ and the distances A and B were changed as appropriate, and a test was conducted on the relationship with changes in the noise level.

Test conditions Engine rotation speed 3000 rpm Engine load condition Full load (load condition such that the engine rotation speed is 3000 rpm with the throttle valve fully open) Port timing Intake port open Eccentric shaft angular position 75° before BDC Intake port closed Eccentric shaft angular position TDC The relationship between the inclination angle θ of the rear 48° screen plate 15 and the noise level is shown in FIG. The noise reduction effect is high when the angle θ is between the angle θ ₁ and the angle θ ₂ . In this example, B=5 mm and A=2.5 mm, so B/A=2.

Further, the distances A and B were varied, and changes in the noise level were investigated under the above test conditions. The result is the 6th
As shown in the figure. In this case, the screen plate inclination angle θ is 59°.
It is. According to this result, a high noise reduction effect appears when B/A=1 to 2.5.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a rotary piston engine according to the present invention, FIG. 2 is a partially enlarged sectional view of the vicinity of the exhaust port of the rotary piston engine of FIG. 1, and FIG. FIG. 3 is a perspective view of a port insert according to the present invention, FIG. 4 is a view taken along the - arrow in FIG. 2, and FIGS. It is a graph showing a relationship. 1... Rotor housing, 2... Side housing, 3... Rotor, 4... Trochoid inner peripheral surface,
6...Intake port, 7...Exhaust port, 8...Port insert, 9...Through hole, 10...Rotor chamber, 16...Horizontal partition plate, 17...Vertical partition plate.

Claims (1)

[Claims] 1. The rotor housing has a horizontal partition plate that partitions an exhaust port opened in the inner circumferential surface of the rotor housing in the circumferential direction of the rotor housing and extends in the flow direction of the exhaust gas, and a cylindrical outer cylinder that encompasses the horizontal partition plate, and In the exhaust port structure of a rotary piston engine, the exhaust port structure of a rotary piston engine includes a port insert inserted in the exhaust flow direction into the exhaust passage portion formed in the housing, and the port insert has a rotor rotation direction in the central portion of the port on the upstream side in the exhaust flow direction. An exhaust port structure for a rotary piston engine characterized by being provided with a screen plate erected to cover the trailing side.