JPH0341652B2 - - 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 rotary piston engine generally 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. Forms 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 has only one approximately oval hole having a long axis in the direction of the rotor's rotational axis, formed on the trochoid inner circumferential surface of the rotor housing. It is designed to open when the Tsukusu seal part is passed through. 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). This structure has the following advantages in terms of reducing exhaust noise:
Although this is effective to some extent, it has the drawback of increasing exhaust passage resistance.

To address the issue of exhaust noise and exhaust resistance,
It has been proposed to provide a horizontal partition plate that partitions the exhaust port in the circumferential direction of the rotor housing, that is, in the short axis direction of the exhaust port, and according to this proposal, the exhaust branch divided by the horizontal partition plate Of the passages, the trailing side branch passage is further divided into smaller sections using vertical partition plates to disperse the exhaust energy immediately after the exhaust port opens, to prevent turbulence of the exhaust, and rapid expansion of the exhaust. In this way, noise is reduced, and the partition plate is disposed only on the trailing side of the port to suppress an increase in passage resistance as much as possible. Dividing the exhaust passage into small sections using partition plates is effective in reducing exhaust noise, but on the other hand, when exhaust gas passes through the exhaust passage, it comes into contact with the partition plates and the temperature increases. This causes a new problem in that the reaction of the exhaust gas in the exhaust passage is inhibited and the emission performance deteriorates.

(Object of the present invention) Therefore, an object of the present invention is to provide an exhaust port structure for a rotary piston engine that can minimize the influence on the reaction in the exhaust passage described above and effectively reduce exhaust noise. It is to provide.

(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 the rotary piston engine exhaust port structure, 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 the rotor housing, wherein the downstream end of the horizontal partition plate in the exhaust flow direction is connected to the rotor housing. It is characterized in that it extends inward by a predetermined amount from the downstream end of the exhaust passage portion.

In order to disperse exhaust energy and prevent exhaust gas from becoming turbulent and rapidly expanding, the longer the partition plate is in the flow direction of the exhaust gas, the more effective it will be, and therefore the more effective it will be at reducing noise. However, on the other hand, since the contact area with the exhaust gas also increases in accordance with the length of the partition plate, the reactivity in the exhaust passage decreases, and therefore the emission performance deteriorates. The present invention
The horizontal partition plate is configured to be shorter than the length of the exhaust passage portion of the rotor housing on the downstream side, so as to minimize the contact area with exhaust gas. Preferably, the horizontal partition plate has a downstream side that is 20 mm wide with respect to the length of the exhaust passage section of the rotor housing.
It is configured to be about 50% shorter.

When the amount of shortening exceeds about 50%, the noise reduction effect decreases significantly, and when it is less than about 20%,
This is because the temperature drop in exhaust gas temperature is large and has a significant effect on emission performance.

(Effects of the Invention) By configuring the partition plate as described above, it is possible to simultaneously prevent deterioration of emission performance without substantially impairing the noise reduction function. Furthermore, in the present invention, since the downstream side of the partition plate is shortened, there is an advantage that the effect on the dividing and rectifying function of the partition plate can be 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. According to the rotation of the rotor 3, the volumes of the working chambers 27a, 27b, and 27c change periodically, thereby forming the intake, compression, explosion, and exhaust steps.
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, from which combustion gas is exhausted from the working chamber 27a during the exhaust stroke.

Referring to FIG. 2, the exhaust port 7 includes one exhaust passage section or through hole 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 is composed of a seat hole portion 9a, an inclined hole portion 9b extending 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 has substantially the same shape as the mouth edge portion 27a. The width of the inclined hole portion 9b in the direction of the rotational axis of the rotor 3 at its inner end, that is, on the rotor chamber 10 side, is slightly larger than the mouth edge 7a, and the length in the direction perpendicular thereto is as wide as the mouth edge. It is larger than the portion 7a, thereby forming a stepped portion S1 on the trailing side and a stepped portion S2 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, 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 .
It protrudes from the inner end and reaches the mouth edge 7a of the through hole 9. The tips 16a and 17b reach a position extremely close to the inner circumferential surface 4 of the rotor housing 1. Further, the rear ends 16b and 17b of the horizontal partition plate 16 and the vertical partition plate 17 are located inward, that is, on the inner circumferential surface 4 side, from the rear end of the port insert 8, and therefore, the horizontal partition plate 16 The vertical partition plate 17 has a notched shape on the downstream side in the exhaust gas outflow direction.

The trailing side of the inclined cylindrical portion 12 extends inward from the tip 12a, that is, toward the inner circumferential surface 4 side, and is bent toward the leading side at the tip, and forms a part between the pair of vertical partition plates 17. A screen plate 15 is formed to cover the. 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 closer to the screen plate 1 than the trailing side open ends 22a, 23a of the second and third exhaust branch passages 22, 23.
It is located on the leading side by the circumferential length of the rotor housing No. 5.

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
The trailing side exhaust passage 21 is further divided into three parts in the width direction of the rotor housing 1 into second, third, fourth exhaust passages 22, 23 and 24, even immediately after the opening where the exhaust gas pressure is particularly high (exhaust energy is large), the exhaust gas flows through the second, third, and fourth exhaust branch passages 22, 2, which have small volumes.
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 act 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.

Furthermore, in this embodiment, the horizontal partition plate 16
Since the downstream side of the vertical partition plate 17 is formed shorter than the port insert 8, the contact area with the circulating exhaust gas is reduced. As a result, the temperature drop while the exhaust gas flows through the port insert 8 is not large enough to inhibit the reaction of the exhaust gas in the exhaust passage, and therefore, good emission performance can be maintained.

In addition, in this embodiment, immediately after the opening of the exhaust port, the fourth exhaust passage, which has a rectangular opening shape among the exhaust branch passages 22, 23, and 24 and whose opening area rapidly increases as the rotor 3 rotates, Branch passage 24
The opening edge on the trailing side is closed with a screen plate 15 so that exhaust gas is discharged only from the second and third exhaust branch passages 22 and 23, which have a small opening area immediately after the opening. And this second and third
Since the exhaust branch passages 22 and 23 are shaped so that the opening area gradually increases as the rotor 3 rotates, a sudden increase in the amount of exhaust gas released immediately after opening is controlled. , turbulence of the exhaust gas flow, and rapid expansion of the exhaust gas are further controlled, 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.

Next, changes in exhaust noise level and exhaust manifold outlet gas temperature were investigated in relation to the lengths of the horizontal partition plate 16 and the vertical partition plate 17. In this case, as shown in FIG.
6a is L, and the distance from the outer surface 1b of the rotor housing 1 to the rear ends 16b, 17b of the horizontal partition plate 16 and the vertical partition plate 17 is l. l/
By varying L, changes in exhaust manifold outlet gas temperature and exhaust noise level were tested.

Regarding the shape of the screen plate 15, as shown in FIG. 2A, there is a shape along the surface of the screen plate 15 on the working chamber 27a side and the inner surface of the inclined hole portion 9b of the exhaust port 7 on the trailing side of the hole portion 9b. The angle formed by the straight line _l1 drawn toward the working chamber, that is, the screen plate inclination angle θ, the distance A between the surface of the screen plate 15 on the working chamber 27a side and the surface forming the working chamber 27a, and the tray of the exhaust port 7. A distance B from the ring side to the top of the screen plate 15 is defined.

In this test, the screen plate inclination angle θ = 59°,
A=2.5mm, B=5mm, port timing...Intake port open, eccentric shaft angular position 75° before BDC, intake port closed, eccentric shaft angular position 48° after TDC.

a Exhaust manifold outlet gas temperature test The maximum value of the exhaust manifold outlet gas temperature was measured during warm-up operation, that is, during a corded start.

This result is shown in FIG. 5. According to this test result, the gas temperature drops significantly when l/L is about 20% or less, and it is thought that the emission performance also deteriorates in this region.

b Exhaust noise level test Exhaust noise level was measured by changing l/L.

Engine speed: 3000 rpm Engine load condition: Full load (load condition where the engine speed is 3000 rpm with the throttle valve fully open) The results are shown in FIG. According to this, it is shown that the noise level becomes high when l/L exceeds about 50%.

[Brief explanation of the drawing]

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 FIG. 5 shows the relationship between the length of the partition plate and the exhaust gas temperature. The graph shown in FIG. 6 is a graph showing the relationship between the length of the partition plate and the noise level. DESCRIPTION OF SYMBOLS 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 defines an exhaust port opened on the inner circumferential surface of the rotor housing in the circumferential direction of the rotor housing, and extends in the flow direction of 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 housing, wherein the downstream end of the horizontal partition plate in the exhaust flow direction is connected to the exhaust passage portion of the rotor housing. An exhaust port structure for a rotary piston engine, characterized in that the exhaust port extends inward by a predetermined amount from the downstream end of the exhaust port.