JPH0647941B2 - Exhaust device for rotary piston engine - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust system for a rotary piston engine, particularly a multi-cylinder rotary piston engine.

(Prior Art) Generally, in a rotary piston engine, an exhaust port opened on a trochoid inner peripheral surface of a rotor housing is sequentially opened and closed by each top portion of the rotor as the rotor rotates. In particular, when the engine is operating at a high rotation speed and a high load, high-temperature, high-pressure exhaust gas is rapidly ejected from the working chamber in the exhaust initial state immediately after the opening of the exhaust port to the exhaust passage side. It is known that a so-called blowdown phenomenon occurs in which the exhaust gas pressure inside the cylinder rapidly increases (see FIG. 4). When a blowdown phenomenon occurs immediately after the opening of the exhaust port, (1) high temperature /
The high-pressure exhaust gas collides with the relatively low-temperature and low-pressure exhaust gas remaining in the exhaust passage to generate a collision wave, which causes large exhaust noise and exhaust vibration or increases exhaust resistance. ) In the middle of the opening of the exhaust passage (i.e., the apex seal on the rotor top is located directly above the exhaust port, and immediately before the end of the exhaust stroke on the leading side in the rotor rotation direction from the exhaust port (in other words, just before the start of the intake stroke) And the working chamber immediately after the start of the exhaust stroke on the trailing side are in temporary communication with each other via the exhaust port), the high-temperature, high-pressure exhaust gas suddenly ejected to the exhaust passage side due to a blowdown phenomenon The exhaust gas flowing into the working chamber immediately before the start of the intake stroke through the exhaust passage causes the phenomenon of blow-by phenomenon, which reduces the charging efficiency of the intake air in the working chamber on the intake side. And thus to live.

Therefore, in order to reduce exhaust noise / vibration and exhaust resistance in the rotary piston engine, it is necessary to take some effective measures to prevent the blowdown phenomenon immediately after the opening of the exhaust port. The applicant has developed and has already proposed an exhaust structure as disclosed in Japanese Patent Publication No. 46-6642 as a specific means for efficiently suppressing the occurrence of the blowdown phenomenon.

By the way, in this known exhaust structure, the exhaust port, which has conventionally been constituted by a single opening, is appropriately separated in the axial direction (thickness direction) of the rotor housing, and has a predetermined dimension in the circumferential direction. It is composed of three small openings that are arranged in a stepwise manner in a state of retreating in sequence, and the above three small openings are opened stepwise in accordance with the rotation of the rotor, so that high temperature and high pressure immediately after the exhaust port opening. The exhaust gas is suddenly jetted out to the exhaust port side as much as possible.

However, in the case where the exhaust port is configured by a plurality of small openings that are sequentially formed in the circumferential direction of the rotor housing in this manner, the occurrence of the blowdown phenomenon immediately after the opening of the exhaust port is suppressed. On the other hand, (1) since the opening length of the exhaust port in the circumferential direction of the rotor housing becomes longer than that of the conventional structure, for example, the exhaust port is located on the trailing side of the rotor rotation direction from the exhaust port via the exhaust port. The communication period between the working chamber located on the leading side and the working chamber located on the leading side becomes longer, and as a result, the blow-through amount of exhaust gas between the working chambers can be increased even though the blowdown phenomenon is suppressed. (2) Since the length of the exhaust port opening in the circumferential direction of the rotor housing becomes longer, it is inevitable compared to the conventional structure. There is no choice but to adopt an alternative structure of advancing the opening timing of the exhaust port or delaying the closing timing of the exhaust port. As a result, for example, when the structure of advancing the opening timing is adopted, it is in an expanded state. Exhaust gas will be exhausted from the exhaust port, and energy loss will increase accordingly, and if a structure that delays the closing timing is adopted, the blow-through amount of exhaust gas may increase accordingly. There was room for improvement in terms of filling efficiency and thermal efficiency.

On the other hand, in the rotary piston engine, since the working chamber in the combustion stroke is a flat space, the flame propagation speed of the air-fuel mixture becomes slower than that of a reciprocating piston engine having a rectangular working chamber space. Due to the structure of the chamber, the absolute amount of intake charge is small during low speed / low load operation, and the opening time of the exhaust port is longer than during high speed operation. Due to the operational characteristics that a large amount of exhaust gas is brought into the working chamber in the intake stroke due to the blow-through of air, and the inert gas component in the air-fuel mixture increases by that much,
There is a risk that the combustibility of the air-fuel mixture will deteriorate during low-load operation, and in order to improve this, the air-fuel ratio of the air-fuel mixture is generally set to the rich side during low-speed / low-load operation.

However, when the air-fuel ratio of the air-fuel mixture is set to the rich side in this way, the combustibility itself is improved, but on the other hand, a large amount of unburned gas components such as HC and CO are generated in the exhaust gas,
This causes a new problem that exhaust emission deteriorates. For this reason, conventionally, in a rotary piston engine, a secondary air port for supplying secondary air is formed near the exhaust port, and in the low speed / low load operation region of the engine, the operation in the exhaust stroke from this secondary air port is performed. An appropriate amount of secondary air is supplied into the room, and unburned gas components generated in the exhaust gas are oxidized and removed by this secondary air to improve exhaust emission. Further, in this case, the secondary air supply amount is supplied in a larger amount than that required for oxidizing and removing the unburned gas components, and at the same time, the exhaust gas and the secondary air are mutually replaced in the working chamber in the exhaust stroke. By reducing the exhaust gas concentration (diluting action of exhaust gas), the amount of exhaust gas blown through the exhaust port from the working chamber in the exhaust stroke to the working chamber side in the intake stroke (that is, the inert gas component). It is intended to further improve the flammability by substantially reducing the carry-in amount).

However, when the secondary air port is formed in the vicinity of the exhaust port as described above, the secondary air is supplied from one side portion of the working chamber toward the working chamber, so that the secondary air and the exhaust gas in the working chamber are discharged. Even mixing and stirring with the gas is relatively difficult, and there is a possibility that the unburned gas components in the exhaust gas cannot be sufficiently oxidized and removed.

Further, since the secondary air is supplied in the vicinity of the exhaust port, the amount of air that has once been supplied into the working chamber but not introduced into the working chamber is directly carried out together with the exhaust gas from the exhaust port to the exhaust pipe side (that is, The amount of short circuit air) is relatively large, so there is not much adverse effect in terms of exhaust purification (that is, the oxidation removal action of unburned gas is performed even in the exhaust passage), but it is replaced with exhaust gas. The amount of secondary air (that is, the amount of air that contributes to the dilution of exhaust gas) is small relative to the total amount of air supplied, and the effect of improving the combustibility by the supply of secondary air cannot be sufficiently obtained.

Further, in order to secure a sufficient amount of the secondary air that contributes to the dilution of the exhaust gas in this way, it is inevitable that the supply amount of the secondary air itself must be increased. This is not preferable because the air supply device becomes large and has a large capacity.

(Object of the Invention) In view of the problems pointed out in the above-mentioned prior art, the present invention reduces exhaust noise, vibration, and exhaust resistance by reducing the occurrence of a blowdown phenomenon immediately after the opening of an exhaust port. (EN) An exhaust device for a rotary piston engine, which is designed to be reduced as much as possible, to improve the intake charging efficiency, and to effectively improve the exhaust gas purification performance and combustibility of the engine by effectively utilizing secondary air. It was made for the purpose.

(Means for Achieving the Object) As a means for achieving the above object, the present invention provides a rotor housing having an intermediate housing and trochoid inner peripheral surfaces disposed on both sides of the intermediate housing, and the rotor. A side housing disposed laterally of the housing at the end of the engine, and a substantially triangular rotor supported by an eccentric shaft in a trochoid space formed by the intermediate housing or the side housing and the rotor housing. In a rotary multi-cylinder rotary piston engine, the working chambers included in a pair of trochoid spaces that are adjacent to each other with an intermediate housing between them extend from immediately before the start of the exhaust stroke to a predetermined stroke period after the start of the exhaust stroke. One of the trochoid spaces at the beginning of the exhaust stroke Exhaust gas blowdown phenomenon occurs in the exhaust port part on the trochoid space side where the exhaust start period working chamber is located between the exhaust start stage working chamber and the other exhaust middle period working chamber on the other trochoid space side in the middle or latter half stage of the exhaust stroke. The intermediate housing is provided with a communication passage communicating at a predetermined timing before the generation, and a secondary air port for supplying secondary air is opened in the communication passage.

(Operation) In the present invention, by the above means, (1) the exhaust start period working chamber of one trochoid space of the pair of adjacent trochoid spaces and the exhaust mid-term working chamber of the other trochoid space are Since they are made to communicate with each other through the communication passage at a predetermined timing before the blowdown phenomenon occurs, a part of the high-temperature and high-pressure exhaust gas in the exhaust start operation chamber is relatively exhausted through the communication passage. The pressure of the trochoid space is reduced to the side of the exhaust medium-term working chamber on the side of the trochoid space, and as a result, the exhaust gas blowdown phenomenon occurs in the exhaust port portion on the side of the exhaust-starting period working chamber as much as possible. (2) The secondary air passes through a communication passage formed at a position relatively distant from the exhaust port, not near the exhaust port located on one side of the working chamber in the exhaust stroke. hand Since it is introduced directly into the inner side of the working chamber, (2-a) the mixing state of the exhaust gas and the secondary air in the working chamber is made good, and the unburned gas component in the exhaust gas due to the secondary air (2-b) The short circuit air amount of the secondary air is reduced compared to the case where secondary air is supplied near the exhaust port, and the exhaust gas is diluted by the secondary air. The action is accelerated, and the amount of the inert gas component brought into the working chamber side in the suction stroke from the working chamber side in the exhaust stroke through the exhaust port along with the exhaust gas is reduced.

(Technical Background of the Invention) In the process of studying a method for effectively suppressing the occurrence of blowdown phenomenon of exhaust gas at the time of opening an exhaust port, the inventors of the present invention featured a configuration of a multi-cylinder rotary piston engine, That is, between a pair of adjacent engine units of a multi-cylinder rotary piston engine in which a plurality of engine units are arranged in the axial direction, the rotors of the engine units rotate with a phase angle of 180 °. However, in that case, the exhaust port of each engine unit repeatedly opens and closes at a 120 ° cycle as the rotor rotates, as shown by the broken curve in FIG.
In addition, between the exhaust port opening / closing characteristic of the first engine unit side and the exhaust port opening / closing characteristic of the second engine unit side, the operation at the initial stage of exhaust of one engine unit (that is, an exhaust gas blowdown phenomenon occurs) region)
And the middle exhaust period of the other engine unit (that is, the operating region where the exhaust gas pressure is relatively low) are in a state of overlapping with each other. In the present specification, the term "exhaust start period" is a concept including not only the initial stage of the exhaust stroke but also the stage immediately before the start of the exhaust stroke, which is closely related to the exhaust stroke, and is further referred to as "exhaust start period working chamber". Is used in the meaning of the working chamber in the stroke stage of the "exhaust start period" defined above) and the middle exhaust working chamber on the other engine unit side (the working chamber in the middle stage of the exhaust stroke). ) Are communicated with each other at a predetermined timing before the exhaust gas blowdown phenomenon occurs, and a part of the high-temperature and high-pressure exhaust gas in the operation start chamber is adjacent to the adjacent exhaust gas To flow into the dynamic chamber, in which conceived to suppress the occurrence of blowdown phenomenon of the exhaust gas in the exhaust onset working chamber side with.

Hereinafter, an exhaust device for a rotary piston engine according to the present invention, which has been made based on the above technical background, will be specifically described based on embodiments.

(Embodiment) (Structure) FIGS. 1 and 2 show a two-rotor rotary piston engine Z for an automobile equipped with an exhaust system according to an embodiment of the present invention.
In the figure, reference numeral 1 is an engine including a pair of side housings 2 and 3, a pair of rotor housings 4 and 5 whose inner peripheral surfaces are trochoidal surfaces, and an intermediate housing 6. Trochoid spaces 10 and 11 are formed inside the rotor housings 4 and 5 on both sides of the intermediate housing 6, which are casings. In the pair of trochoid spaces 10 and 11, rotors 7 and 8 which make planetary rotational motion around the eccentric shaft portion 9a of the eccentric shaft 9 are fitted, respectively, and on the three sides of the rotors 7 and 8, respectively. Three working chambers 10A, 10B, 10C and 11A, 11B, 11C
The first engine unit X ₁ and the second engine unit X ₂ having the above are configured.

As shown in FIGS. 1 and 2, the intermediate housing 6 has the intermediate housing 6
The sliding surface 6a of the first engine unit X ₁ side of the second
A pair of left and right intake ports 13A to each opening on the sliding surface 6b of the engine unit X ₂ side, 14A are formed. The two intake ports 13A and 14A are respectively paired with intake ports 13B and 14B formed in the pair of side housings 2 and 3, respectively, and intake pipes 18 are connected to the outer ends thereof, respectively. There is.

On the other hand, in the rotary housings 4 and 5 of the engine units X ₁ and X ₂ , as shown in FIG. 1 and FIG. Exhaust ports 15 and 16 opening on the surface are formed, respectively. These two exhaust ports 15,
16 are corresponding rotors 7, as shown in FIG.
With the rotation of 8, the top of each rotor opens and closes with a rotation cycle of 120 °, but the opening / closing phase difference between the _two is as shown by broken curves l ₁ and l ₂ ,
It has a phase difference of 180 ° based on the rotational phase difference of 8. Therefore, the two exhaust ports 15 and 16 are provided with a predetermined period from a predetermined period before the opening of one exhaust port 15 to the first half of the opening period of the same exhaust port 15 and the other exhaust port 16.
The middle or second half of the opening period of will overlap each other.

Therefore, in this embodiment, the present invention is applied to the intermediate housing 6 so that the communication passage 12 penetrating the intermediate housing 6 in the thickness direction thereof.
Through the communication passage 12, and in the trochoid space 10 (or 11) of one of the engine units, the exhaust start period working chamber (for example, the second engine unit X ₂ in the rotor rotation position shown in FIG. 1) is formed. Side exhaust working chamber 1
1A) and the trochoid space 11 of the other engine unit
(Or 10) exhaust medium-term working chamber (for example, the exhaust working chamber 1 on the side of the first engine unit X _{1 in} FIG. 1)
0A) are communicated with each other. In this case, in this embodiment, the opening start timing of the communication passage 12 is set to the exhaust port 15 (or 1) as shown in FIG.
6) The timing is set slightly earlier than the opening start timing of 6), while the closing timing of the communication passage 12 is set considerably earlier than the closing timing of the exhaust port 15 (or 16). Therefore, the opening period of the communication passage 12 on the first engine unit X ₁ side and the opening period of the communication passage 12 on the second engine unit X ₂ side overlap with each other with a predetermined phase difference, and the overlapping period of the both (The period indicated by (θ) in FIG. 3) is the period during which the communication passage 12 is actually open.

In the present invention, the opening timing of the communication passage 12 is set to the exhaust port 15 (or 16) as in the example of FIG.
The opening timing of the exhaust port 15 is not limited to a timing slightly earlier than the opening timing of the exhaust port 15.
In order to achieve the purpose of suppressing the blowdown phenomenon in the (or 16) portion, it may be in the vicinity of the opening start point of the exhaust port 15 (or 16), for example, the exhaust port 15 (or 16) is opened at the same time. In some cases.

The shape of the opening edge of the exhaust ports 15 and 16 is a flat opening that is narrow in the circumferential direction of the trochoidal surface and wide in the width direction, but this is based on the requirements of the operating performance of the engine. In other words, (1) In order to prevent the intake charging efficiency from decreasing due to the exhaust gas blow-through phenomenon at the exhaust port, set the leading edge of the exhaust port on the leading side in the rotor rotation direction to the trailing side as much as possible and set the exhaust port closing timing. (2) From the viewpoint of effectively utilizing the energy of combustion gas, set the exhaust port rotor rotation direction trailing side edge to the leading side as much as possible to open the exhaust port. The opening width in the circumferential direction of the trochoidal surface of the exhaust port is kept as small as possible for two reasons that it is effective to delay the timing.
On the other hand, as the exhaust resistance increases, the output loss of the engine also increases, so from the standpoint of improving output characteristics, the opening area of the exhaust port should be as large as possible to minimize exhaust gas flow resistance in the exhaust port. Therefore, the exhaust port is largely opened in the width direction on the trochoidal surface.

A trumpet-shaped exhaust insert 21 is attached to the inner surfaces of the outer ends of the exhaust ports 15 and 16, and the exhaust pipe 17 is attached to the outer end of the exhaust insert 21.
Are connected. Further, in FIG. 2, reference numeral 19 is a water jacket.

Further, in this embodiment, the present invention is applied to open the secondary air port 30 for supplying secondary air in the communication passage 12 of the intermediate housing 6.
A secondary air supply pipe 31 is connected to the outer end portion of the secondary air port 30. An air pump 33 is attached to the upstream end of the secondary air supply pipe 31, and a control valve 32 is attached to the downstream side of the air pump 33. The control valve 32 is composed of a tire flam valve that operates in accordance with the intake negative pressure of the engine.
8, the valve body 38 is displaced in the axial direction substantially by the magnitude of the intake negative pressure introduced into the pressure chamber 37 via the negative pressure introduction pipe 35 opening at the downstream position of the throttle valve 34, and The first valve opening 39A communicating with the next air port 30 and the second valve opening 39B communicating with the atmosphere are selectively opened and closed. In this embodiment, the opening of the throttle valve 34 is small and a large intake negative pressure is generated in the intake pipe 18 during low speed and low load operation of the engine. Next Airport 3
The operating characteristic of the control valve 32 is set so that it communicates with the 0 side and the second valve port 39B is opened and the air pump 33 is opened to the atmosphere in other operating regions.

(Operation and Its Action) Next, the operation of the rotary piston engine Z and its action will be described together with FIG. 3 to FIG.

When the engine is operated, each engine unit X ₁ , X
₂ , the rotors 7 and 8 make planetary rotational movements around the eccentric shaft 9, and the working chambers 10A, 10B, 10C and 11A, 1A formed on the three periphery of the rotors 7 and 8 respectively.
The air-fuel mixture sucked into 1B and 11C sequentially undergoes compression-explosion-expansion steps, and then is discharged to the exhaust pipe 17 side through the exhaust ports 15 and 16. In this case, if the communication passage 12 is not formed in the intermediate housing 6, immediately after the exhaust ports 15 and 16 are opened, high-temperature and high-pressure exhaust gas is discharged from the exhaust initial working chamber to the exhaust passage side as shown in FIG. A blowdown phenomenon occurs in which the exhaust pressure on the exhaust passage side rises rapidly due to sudden ejection, and as a result, the relatively low-pressure residual exhaust gas remaining in the exhaust passage collides with the ejected exhaust gas. A collision wave is generated, which causes a large amount of exhaust noise and vibration, and a large amount of exhaust gas is rapidly discharged, which increases exhaust resistance and causes engine output loss, or exhaust gas pressure. As described above, there is a possibility that such an increase in the amount of exhaust gas passing through the exhaust ports 15 and 16 to the side of the intake working chamber increases, resulting in a decrease in intake charging efficiency. It is as.

However, in the embodiment, the communication passage 12 is formed in the intermediate housing 6 by applying the present invention, and the exhaust start period working chamber of one engine unit and the other engine are formed through the communication passage 12. Since it is designed to communicate with the exhaust medium-term working chamber of the unit,
As shown by the arrow G in each of the drawings and FIG. 3, a part of the high-temperature, high-pressure exhaust gas G inside the exhaust-start-stage working chamber flows out to the exhaust middle-stage working chamber side through the communication passage 12. Therefore, in the working chamber at the beginning of exhaust, the amount and the gas pressure of the exhaust gas ejected from the exhaust port 15 (or 16) are reduced by the amount of outflow to the side of the middle working chamber for exhaust, so that the solid curve in FIG. As shown in, the increase in exhaust gas pressure on the exhaust port side immediately after opening the exhaust ports 15 and 16 is suppressed to be smaller than that in the case of the conventional structure (that is, without the communication passage 12, see FIG. 5, broken curve). Therefore, the occurrence of the blowdown phenomenon of the exhaust gas is suppressed as much as possible (the blowdown is suppressed only in the shaded portion in FIG. 5).

Therefore, it is possible to prevent the above-mentioned problems caused by the occurrence of the exhaust gas blowdown phenomenon, that is, increase in exhaust noise and vibration, engine output loss, and decrease in intake charging efficiency as much as possible.

The opening area of the exhaust ports 15 and 16 is the minimum area where the exhaust resistance can be suppressed to a predetermined value or less in the state where the exhaust gas flow rate is maximum, that is, in the high load operation state and immediately after the opening of the exhaust port. However, as in the above embodiment, a part of the exhaust gas is discharged from the working chamber side at the exhaust start stage to the exhaust port (15
Alternatively, if the gas is allowed to flow to the exhaust medium-term working chamber side where there is a margin in the opening area of 16), the amount of exhaust gas passing through the exhaust port (16 or 15) on the other side at the initial stage of exhaust is reduced by the amount of the above-mentioned outflow. It is possible to reduce the opening area of the exhaust ports 15 and 16. In this way, if the opening area of the exhaust ports 15 and 16 can be reduced, the edge of the exhaust ports 15 and 16 on the leading side in the rotor rotation direction is set closer to the trailing side and the exhaust ports 15 and 16 are set. You can accelerate the blockage timing of
Blow-through of exhaust gas to the intake working chamber side through the exhaust ports 15 and 16 can be further suppressed, and the intake charging efficiency is improved accordingly.

On the contrary, it is also possible to delay the opening timing of the exhaust port 14 by setting the trailing side edges of the exhaust ports 15 and 16 on the trailing side in the rotor rotation direction to the leading side. The energy can be effectively used and the thermal efficiency is improved.

On the other hand, the low-speed / low-load operating region of the engine (that is, a large amount of unburned gas component is generated in the exhaust gas, and the opening time of the exhaust ports 15 and 16 is relatively long, the exhaust ports 15 and 16 are In the operating region where the amount of exhaust gas blown through from the working chamber in the exhaust stroke to the working chamber in the suction stroke increases), the control valve 32 allows the secondary air port 30 to communicate with the air pump 33 side. The pressurized air discharged from the air pump 33 is supplied as secondary air from the secondary air port 30 into the communication passage 12 as indicated by an arrow A in FIG. The secondary air A thus supplied into the communication passage 12 is discharged when the communication passage 12 is opened, that is, in the trochoid space 10 (or 11) of the one engine unit. At the rotor rotation position shown in the figure, the exhaust working chamber 11A on the _second engine unit X ₂ side and the trochoid space 11 (or 1) of the other engine unit
0) when the exhaust medium-term working chamber (for example, the exhaust working chamber 10A on the side of the first engine unit X ₁ ) communicates with each other through the communication passage 12, the exhaust gas G flowing through the communication passage 12 Is introduced into the exhaust medium-term working chamber together with the exhaust gas G.

The secondary air A introduced into the exhaust medium-term working chamber through the communication passage 12 acts to stir and mix with the exhaust gas G in the working chamber to oxidize and remove unburned gas components in the exhaust gas G. To do. In this case, in this embodiment, the secondary air A
Is not from the vicinity of the exhaust port that opens to one side of the working chamber, but as shown in FIG. 1, the exhaust mid-term working chamber (for example, the exhaust working chamber 10 of the first engine unit X _{1 in} FIG. 1).
Since it is introduced into the working chamber from the communication passage 12 that opens in the substantially central portion of A), the stirring and mixing of the secondary air A and the exhaust gas G is swift and almost even in almost the entire working chamber. Therefore, as compared with the case where the secondary air A is introduced into the working chamber from the vicinity of the exhaust port 15, the secondary air A is performed.
The mixing state of the exhaust gas G with the exhaust gas G is improved, and the oxidation removal action of the unburned gas component in the exhaust gas G by the secondary air A is promoted accordingly, and the exhaust gas purification performance is improved.

Further, the secondary air A introduced into the working chamber also replaces the exhaust gas G in the working chamber to dilute the exhaust gas G remaining in the working chamber. With the structure in which the gas G is introduced into the working chamber from a position near the exhaust port 15 (or 16), even if the secondary air A is introduced into the working chamber, unburned gas in the exhaust gas in the working chamber is not eliminated. The exhaust port 15 with almost no oxidation removal of gas components or dilution of exhaust gas
(Or 16), the amount of secondary air discharged to the exhaust passage side, that is, the short circuit air amount increases, and as a result, the exhaust gas G in the working chamber in the exhaust stroke remains at a relatively high concentration Through the suction chamber to the side of the working chamber in the suction stroke, and as a result, the substantial amount of working gas (mixture) filled in the working chamber in the suction stroke is reduced by an amount corresponding to the amount of exhaust gas that has blown through. Instead, the amount of inert gas component in the mixture increases due to the mixed exhaust gas,
As described above, the flammability deteriorates.

However, in this embodiment, as described above, the present invention is applied and the secondary air port 30 is replaced with the exhaust port 15.
(Or 16) is opened in the communication passage 12 formed at a position relatively distant from (or 16), so that the secondary air A supplied into the working chamber is exhausted with almost no contribution to the dilution action of the exhaust gas. The amount of short circuit air discharged from the port as it is is reduced as much as possible. Therefore, the action of diluting the exhaust gas G by the secondary air is promoted, and the amount of the inert gas component brought into the working chamber side in the intake stroke from the working chamber in the exhaust stroke together with the exhaust gas G is reduced as much as possible. However, the combustibility of the air-fuel mixture is improved accordingly.

Further, the supply amount of the secondary air is preset so that the oxidation removing action of the unburned gas components and the exhaust gas diluting action are properly performed, but in the embodiment, Since the secondary air is supplied to a position distant from the exhaust port, the amount of the short circuit air of the secondary air is smaller than that in the case where the secondary air is supplied near the exhaust port. It is possible to reduce the supply amount itself (that is, the size and capacity of the secondary air supply device can be reduced).

(Effects of the Invention) An exhaust device for a rotary piston engine according to the present invention includes an intermediate housing, a rotor housing having trochoid inner peripheral surfaces disposed on both sides of the intermediate housing, and an engine end lateral to the rotor housing. A multi-cylinder rotary piston having a side housing disposed in a portion thereof, and a substantially triangular rotor supported by an eccentric shaft in a trochoidal space formed by the intermediate housing or the side housing and a rotor housing In the engine, one of the working chambers contained in a pair of trochoid spaces that are adjacent to each other with the intermediate housing in between is in the exhaust stroke start period that extends from immediately before the exhaust stroke starts to the predetermined stroke period after the exhaust stroke starts. Trochoid space side exhaust start operation Between the chamber and the other trochoid space in the middle or the latter half of the exhaust stroke, and the predetermined period before the exhaust gas blowdown phenomenon occurs at the exhaust port on the trochoid space side where the exhaust start working chamber is located. Is provided in the intermediate housing, and a secondary air port for supplying secondary air is opened in the intermediate passage.

Therefore, according to the exhaust device of the rotary piston engine of the present invention, (1) the exhaust start period working chamber of one trochoid space of the pair of trochoid spaces adjacent to each other and the exhaust mid-term working chamber of the other trochoid space are exhausted. At the predetermined timing before the gas blowdown phenomenon occurs, they are communicated with each other through the communication passage, so at the beginning of the exhaust stroke, part of the high temperature, high pressure exhaust gas in the exhaust start period working chamber is connected to the above-mentioned communication. Exhaust gas blowdown phenomenon may occur in the exhaust port part on the side of the discharge start period working chamber where the exhaust gas pressure is relatively low via the passage to the other trochoid space side. Is effectively and effectively suppressed,
As a result, the effects of reducing exhaust noise and vibration and exhaust resistance due to the blowdown phenomenon and improving the charging efficiency of intake air can be obtained.

(2) The secondary air is not in the vicinity of the exhaust port on one side of the working chamber in the exhaust stroke but inside the working chamber via the communication passage formed at a position relatively distant from the exhaust port. Since it is directly introduced to the side, (2-a) the mixing state of the exhaust gas and the secondary air in the working chamber becomes good, and the oxidation removal action of the unburned gas component in the exhaust gas by the secondary air is promoted, The exhaust purification performance of the engine is improved by that much. (2-b) The short circuit air amount of the secondary air is reduced compared to the case where secondary air is supplied near the exhaust port, and the exhaust gas generated by the secondary air is reduced. Since the diluting action of is promoted, the inert components brought into the working chamber in the suction stroke from the working chamber side in the exhaust stroke through the exhaust port together with the exhaust gas are reduced, and the combustibility is improved accordingly. And so on. It

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of a main part of a rotary piston engine equipped with an exhaust system according to an embodiment of the present invention, and FIG.
II-II transverse sectional view, FIG. 3 is an operating characteristic diagram of the exhaust port and the communication passage of the rotary piston engine shown in FIG. 1, 4
FIG. 5 and FIG. 5 are exhaust gas pressure characteristic diagrams. 1 …… Engine casing 2,3 …… Side housing 4,5 …… Rotor housing 6 …… Intermediate housing 7,8 …… Rotor 9 …… Eccentric shaft 10,11 …… Trochoid space 12 …… Communication passage 13A , 13B, 14A, 14B …… Intake port 15, 16 …… Exhaust port 17 …… Exhaust pipe 18 …… Intake pipe 30 …… Secondary air port 31 …… Secondary air supply pipe X ₁ , X ₂ …… Engine unit

Claims (1)

[Claims] 1. An intermediate housing, a rotor housing having trochoid inner peripheral surfaces disposed on both sides of the intermediate housing, and a side housing disposed laterally of the rotor housing at an end of the engine. In a multi-cylinder rotary piston engine in which a substantially triangular rotor is supported by an eccentric shaft in a trochoidal space formed by an intermediate housing or a side housing and a rotor housing, and a planetary rotary motion is performed, the intermediate housing is sandwiched. Of the working chambers included in a pair of adjacent trochoid spaces, the one exhaust chamber of the trochoid space, which is in the exhaust stroke start period immediately before the start of the exhaust stroke and extends over the predetermined stroke period after the start of the exhaust stroke, The other toro in the middle or second half of the exhaust stroke The intermediate passage for communicating with the mid-term exhaust working chamber on the id space side at a predetermined timing before the blowdown phenomenon of the exhaust gas occurs at the exhaust port portion on the trochoid space side where the exhaust starting period working chamber is located. An exhaust device for a rotary piston engine, wherein the exhaust device is provided in a housing and a secondary air port for supplying secondary air is opened in the communication passage.