JPH0396624A - Pumping loss reduction device for engine - Google Patents

Abstract

PURPOSE:To enhance stability in combustion by constituting a device in such a way that the close ending time of a recessed hole is delayed from the open ending time of a late closing port by a specified angle in the pumping loss reduction device wherein the side housing a rotary piston engine is provided with an air intake late closing port and a recessed hole. CONSTITUTION:When the side housing 3 of a rotary piston engine is provided with an air intake late closing port 21 for reduction in pumping loss and recessed hole 25 which communicates working chambers 7 with the space 26 of a rotor side section within a side seal 9, the air intake late closing port 21 is opened to a space within a cylinder at a position somewhat close to the leading side from air intake ports 17 and 18 when viewed from the rotor rotating direction so that it is thereby opened/closed by the rotation of a rotor 5. On the other hand, the recessed hole 25 is provided at the position of suction side close to the minor axis L2 in the compression side close to the major axis L1 of a casing 1, and it is concurrently interposed into a relative position that the close ending time of the recessed hole 25 by the rotor is delayed from the open ending time of the air intake late closing port 21 by a specified angle.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a device for reducing pumping loss in a rotary piston engine and improving combustibility under light loads.

[Conventional technology]

Conventionally, in rotary piston engines, in order to reduce pumping loss at low loads and improve fuel efficiency, the side housing was provided with an intake slow-close port that was opened and closed by the rotor and closed later than the intake port, separate from the intake port. A device is known. For example, JP-A-63-715
In the device disclosed in Publication No. 25, intake slow-closing ports provided in each side housing of a rotary piston engine are communicated between cylinders via communication passages equipped with control valves, and the intake ports are connected to each other in a predetermined operating range. By opening the communication passage and allowing a portion of the intake air from the cylinder at the beginning of the compression stroke to flow into the other cylinder at the front stage of the intake stroke, intake negative pressure is suppressed and pumping loss is reduced. In addition, in the device disclosed in this publication, during low rotation speeds and light loads such as when idling, the communication passage is closed to reduce pumping loss in order to avoid destabilizing combustion due to dilution gas being brought in. I'm trying to stop the control.

[Problem to be solved by the invention]

By the way, apart from the pumping loss reduction measures mentioned above, the air-fuel mixture with good ignitability under light loads is unevenly distributed near the spark plugs, especially in rotary piston engines where each spark plug is provided with a pair of spark plugs. There is a technology that attempts to improve combustion stability by locating it unevenly near the leading side spark plug. As this type of technology, for example, one in which a fuel injection valve is provided to directly supply fuel to the compression combustion chamber has been known.
It is desired to achieve combustion stability with a simpler structure.

Therefore, the applicant has provided a recessed hole in the side housing of a rotary piston engine that is opened and closed by the rotor to communicate the working chamber with the rotor side space inside the side seal at predetermined times during the latter half of the intake stroke and during the compression stroke. The fuel-air mixture that has become well atomized in the rotor side space is sent to the leading side of the working chamber through the recessed hole, thereby improving combustion stability. I thought about it and filed the application first (Japanese Patent Application Laid-open No. 1-72467)
issue). This device will be described with reference to FIG. 11. As the rotor 105 rotates, the recessed hole 125 shown in FIG. It is closed to the working chamber 107 during the compression stroke of the chamber 107 (the state shown in FIG. 11), and is positioned inside the side seal 109 of the rotor 105 until the compression stroke working chamber passes the compression top dead center. It is provided at a predetermined position on the side housing 103. During the compression stroke, before the recessed hole 125 is fully opened, the working chamber 107 and the rotor side space inside the side seal 109 are communicated with each other, and a part of the air-fuel mixture is introduced into the rotor side space. After the atomization of the air-fuel mixture is promoted within the space, and before the recessed hole 125 for the working chamber is fully opened in the latter half of the intake stroke, this working chamber and the rotor side space are communicated, and the air-fuel mixture in a well-atomized state is conveyed. It is designed to be supplied to the leading side of the working chamber.

Although this device has a simple structure, the stratification effect that unevenly distributes the well-atomized air-fuel mixture on the leading side of the working chamber improves combustion stability under light loads.

In particular, when this device is combined with the aforementioned pumping loss reduction device equipped with the intake late closing port, combustion can be stabilized even under light loads such as during idling, where conventional pumping loss reduction control would have caused combustion fluctuations. It can be expected to have a great effect when reducing bombing loss.

However, as shown in FIG. 11, the recessed hole 125 is provided at a predetermined position of the side housing 103 where the above-mentioned effect can be obtained, and the intake slow closing port 121 is provided in the same side housing 3 as in the conventional case. If they are arranged in this manner, there is a problem in that they influence each other and the effect of improving combustion stability is impaired. That is, in the positional relationship between the intake slow closing port 121 and the recessed hole 125 as shown in FIG.
07, the side seal 109 along the next working chamber 107' passes through the intake late closing port 121, thereby closing the intake late closing port 1.
21 opens, and the time when the intake late closing port 121 finishes opening (fully open) is later than the time when the recessed hole 125 finishes closing.And when the side seal 109 crosses the intake late closing port 121, The rotor side space communicates with the working chamber 107' through the intake slow closing port 121. Therefore, when the air-fuel mixture flows into the rotor side space from the working chamber 107 during the compression stroke through the recessed hole 125, Due to the increase in compression pressure, a large amount of the air-fuel mixture that flows in just before the concave hole 125 finishes closing escapes into the next working chamber 107' through the intake late closing port 121.

Therefore, the amount of air-fuel mixture stored in the rotor side space decreases, reducing the effect of stabilizing combustion, and furthermore, the problem arises that the effective compression ratio also decreases significantly.

In view of the above-mentioned circumstances, the present invention reduces pumping loss by using an intake late-closing port, and improves combustion stability at light loads by providing a recessed hole at a predetermined position in the side housing. Prevents functional deterioration due to mutual influence between late-closing port and recessed hole,
It is an object of the present invention to provide a pumping loss reduction device for an engine that can effectively exhibit the effect of reducing pumping loss and the effect of improving combustion stability.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the first invention includes an intake late closing port that is opened and closed by the rotor and closes later than the intake port in the side housing of the rotary piston engine. At the same time, the rotor opens and closes the intake stroke working chamber to the compression stroke working chamber, and communicates the working chamber with the rotor side space inside the side seal at each predetermined period before and before fully opening the working chamber. An engine pumping loss reduction device provided with a recessed hole,
The intake late-closing port and the recessed hole are provided in the same side housing, and the positional relationship is such that the time when the rotor finishes closing the recessed hole with respect to the working chamber is delayed by a predetermined angle from the time when the late-closing port ends opening. The slow-closing port and the recessed hole are provided.

Further, the second invention provides a side housing of the rotary piston engine with an intake late closing port that is opened and closed by the rotor and closes later than the intake port, and is also opened and closed by the rotor to transfer the intake stroke working chamber from the compression stroke working chamber. An engine pumping loss reduction device having a concave hole that opens and communicates the working chamber with the rotor side space inside the side seal at predetermined periods before and before fully opening the working chamber. The intake slow closing port is provided in one of the opposing side housings, and the recessed hole is provided in the other side housing.

[Effect]

According to the structure of the first invention, the late-closing port has the effect of reducing the intake negative pressure and reducing pumping loss, while the recessed hole allows the air to be removed from the rotor side from the working chamber during the compression stroke. A stratification effect can be obtained in which the air-fuel mixture flows into the space, promotes atomization of the air-fuel mixture in the rotor side space, and then sends the air-fuel mixture to the leading side of the working chamber. and,
By setting the time at which the rotor finishes closing the recessed hole relative to the working chamber to be delayed by a predetermined angle from the time at which the intake late closing port ends opening, the recessed hole passes from the working chamber during the compression stroke. When the air-fuel mixture flows into the rotor side space, it is possible to avoid a situation in which the air-fuel mixture, which flows in a large amount immediately before the concave hole finishes closing, flows out into the next working chamber through the intake late closing port.

Further, according to the structure of the second invention, the above-mentioned effects of the intake slow-closing port and the effects of the recessed hole can be obtained, and the intake slow-closing port and the recessed hole are provided in separate side housings with the rotor in between. This prevents communication between the rotor side space on the concave hole side and the intake slow closing port.

(Example) Embodiments of the present invention will be described based on the drawings.

1 to 3 schematically show the structure of a rotary piston engine equipped with a pumping loss reduction device according to a first embodiment of the present invention. In these figures, a casing 1 of a rotary piston engine includes a rotor housing 2 whose inner peripheral surface 2a is formed in a trochoid shape and side housings located on both sides of the rotor housing 2. It is equipped with two rotor housings 2.2 arranged in the middle, a side housing (intermediate housing) 3 located in the middle thereof, and side housings 4, 4 on both outer sides, and each cylinder is constituted by these. has been done. A substantially triangular rotor 5 is accommodated in the space within each cylinder, and each rotor 5 is supported by an eccentric shaft 6 and rotates planetarily. The rotor 5 divides the space within the cylinder into three working chambers 7, and as the rotor 5 rotates, intake, compression, explosion, and exhaust strokes are performed.

The rotor 5 has an avex seal 8 in sliding contact with the inner circumferential surface of the rotor housing 2ak at each top in order to seal between each working chamber 7, and an arcuate side seal 9 along each side of both sides. There are also 10 corner seals on both sides of each top.
are each installed. Furthermore, oil seals 11 are installed on both inner circumferential side surfaces of the rotor 5.

The rotor housing 2 of the casing 1 is formed with an exhaust port 13 that communicates with the exhaust passage 12 and opens into the working chamber 7 at a position where the exhaust stroke is to be performed, and on the leading side where the explosion stroke is to be performed. A pair of spark plugs 14, 15 are attached to the and trailing sides.

Further, the side housing 3.4 is formed with an intake port that communicates with the intake passage 16 and opens into the working chamber 7 at a position where an intake stroke is to be performed. As the intake ports, a primary intake port 17 for low load and a secondary intake port 18 for high load are usually opened at opposite positions. In this case, it is necessary to provide intake ports for both sides of the intermediate side housing 3, respectively;
Because the secondary intake port 18 needs to have a larger passage area than the primary intake port 17, the primary intake port 17 is provided in the intermediate side housing 3, and the secondary intake port 17 is provided in the side housing 4 on the opposite side. Next intake port 1
8 are arranged.

Further, the side housing is provided with a recessed hole 25 that communicates between an intake slow-closing port 21 for reducing pumping loss and a rotor side space 26 inside the working chamber 7 side seal 9 during a predetermined interval (described later). ing.

The intake late-closing port 21 opens into the space inside the cylinder at a position slightly on the leading side of the intake port 17.18 when viewed from the rotor rotational direction.
The intake ports 17 and 18 are opened and closed during the intake stroke, and are arranged to be closed at the early stage of the compression stroke, later than the closing timing of the intake ports 17 and 18. The intake slow closing ports 21 and 21 provided for each air vent are connected to the communication path 2.
The communication passage 22 is provided with a control valve 23 that is controlled by a control circuit (not shown) and opens and closes the communication passage 22 according to the operating state.

When the communication passage 22 is open, a portion of the intake air from the working chamber 7 at the beginning of the compression stroke of one gas passes through the passage 22 to the working chamber during the intake stroke of the other gas. 7, the intake negative pressure is suppressed and pumping loss is reduced. In this embodiment, in order to simplify the structure for reducing pumping loss, intake slow closing ports 21 for each air pump are provided on both sides of the intermediate side housing 3, and communication passages 22 are provided on both sides of the intermediate side housing 3. It is formed to penetrate through.

On the other hand, the recessed hole 25 is provided in the side housing 3 on the compression side of the long axis L1 of the casing 1 and on the intake side of the short axis L2, and is opened and closed by the rotor 5 to open from the intake stroke working chamber to the compression stroke working chamber. At the same time, the working chamber and the rotor side space 26 inside the side seal are communicated with each other during predetermined periods before and after the working chamber 7 is fully opened. Further explanation with reference to FIGS. 4 to 6:
The recessed hole 25 is opened at a position closer to the leading side of the working chamber in the latter half of the intake stroke, indicated by reference numeral 7A in FIG. The working chamber 7Eh is closed at a predetermined time in the middle of the compression stroke to reach the state shown by 7B1, and the working chamber of the compression stroke reaches compression top dead center (the state shown by 7C in FIG. 6). The rotor 5 is located inside the side seal 9 of the rotor 5 until it passes through. Then, there is a predetermined period from the beginning of opening of the recessed hole 25 for the working chamber 7A in the latter half of the intake stroke to the end of opening (fully opened), and a predetermined period from the beginning of closing of the recessed hole 25 for the working chamber 7B1 to the end of closing during the compression stroke. In this case, the side seal 9 is inserted into the recessed hole 25.
When passing through, the working chamber outside the side seal 9 and the rotor side space 26 inside the side seal 9 are communicated with each other.

This recessed hole 25 is located at the secondary intake port 1 as will be described in detail later.
In order to prevent the stratified air-fuel mixture from escaping to the intermediate side housing 3, which is the side on which the primary side intake port 17 is provided, the concave hole 25 and the intake late closing port 21 are connected to each other. are provided in the same side housing 3.

In particular, the positional relationship is such that the timing at which the recessed hole 25 finishes closing for the working chamber B1 in the middle of the compression stroke in FIG. , the above slow closing port 2
1 and a recessed hole 25 are provided. Specifically, as follows, under the constraints to satisfy the functions of the slow-closing port 21 and the recessed hole 25, the slow-closing intake port 21 is made smaller than the conventional slow-closing intake port (see FIG. 11). It is set to open early.

That is, in order to obtain the combustion stabilizing effect of the recessed hole 25 described later, the position of the recessed hole 25 is limited, and on the other hand, in order to obtain the pumping loss reduction effect of the intake late closing port 21, the position of the recessed hole 25 is limited. The positions of the side 21a and the side 2lb on the closed end side are also restricted. Under these restrictions, by flattening the intake late closing port 21 and moving the side 21C on the opening end side closer to the opening side 21a, the timing at which it ends closing is made earlier.

The opening/closing relationship between the recessed hole 25 and the intake slow closing port 21 is shown in a timing chart as shown in FIG. 7. This figure shows the open transition period AO from the beginning of opening to the end of opening (fully open) of the recessed hole 25 for one working chamber, the closing transition period AC from the beginning of closing to the end of closing, and the slow intake closing for the next working chamber. The transition period BO from the beginning of opening to the end of opening (fully open) of the port 21 is represented by a chevron-shaped line.As shown in this figure, the timing of the beginning of closing of the recessed hole 25 with respect to the working chamber during the compression stroke and the next Although the opening timing of the intake late closing port 21 with respect to the working chamber is almost the same, the opening timing of the intake late closing port 21 is brought forward, so that the concave hole 25 opens a predetermined angle Δθ later than this timing. Closing is completed. The predetermined angle Δθ is
during the closing transition period AO (that is, the working chamber 7Bt in the middle of the compression stroke)
This period is set to correspond to a period in which more air-fuel mixture flows from the working chamber 7B1 to the rotor side space 26 due to an increase in compression pressure.

In order to effectively exhibit the effects of pumping loss reduction and combustion stabilization, the intake late-closing port 21 starts opening at about 85° ATDC, finishes opening at about 110' ATDC, and starts closing at about 110' ATDC. ATDC
The recessed hole 25 is set at about 320', the closing time is set at about ATDC 400', and the opening time of the recessed hole 25 is set at about ATDC.
It is desirable to set the opening end time to about 250", the opening end time to about ATDC 290", the closing start time to about ATDC 440", and the closing end time to about ATDC 490'.

In the device of this embodiment as described above, while the pumping loss is reduced by the intake late closing port 21,
Combustion at light loads is stabilized by the stratification effect of supplying a well-atomized air-fuel mixture to the leading side of the working chamber 7 through the concave holes 26.

The layering effect of the recessed holes 26 will be explained with reference to FIGS. 4 to 6. In the state shown in FIG. 5, as the rotor 5 rotates from the two-dot chain line position to the solid line position, the recessed hole 25 gradually closes with respect to the working chamber 7B1 in the middle of the compression stroke, and from the beginning of closing to the end of closing. In between, the working chamber 7B+ and the rotor side space 26 are communicated through the recessed hole 25, and a part of the air-fuel mixture flows from the working chamber 7B1 into the rotor side space 26 due to the pressure difference between the two. When the rotor 5 further rotates to the state shown in FIG. 6, the inside of the working chamber 7C near the compression top dead center becomes high temperature and high pressure due to ignition, and a part of the gas leaks through the side seal 9 and enters the rotor side space 26. The air-fuel mixture enters the air-fuel mixture and mixes with the air-fuel mixture that flowed in earlier, resulting in rapid atomization of the air-fuel mixture.

When the rotor 5 rotates to the state shown in FIG. 4, the working chamber 7A in the latter half of the intake stroke and the rotor side space 26 are communicated through the concave hole 25, and a good atomization state is obtained from the rotor side space 26. The stratifying air-fuel mixture is injected into the leading side of the working chamber 7A through the concave hole 25. Therefore, at the time of ignition, a stratified state in which the air-fuel mixture in a good atomized state is unevenly distributed near the leading side ignition plug 14 is obtained, and combustion stability is improved.

By the way, in this embodiment, when the concave hole 25 for the working chamber 7B1 finishes closing during the compression stroke in FIG. Since the closing timing is set to be delayed by a predetermined angle Δθ from the opening end timing of the slow closing port 21 for the next working chamber 7B2, the intake slow closing port 21 and the recessed hole 25 are located in the same side housing 3. Even if it is provided, the air-fuel mixture that flows from the working chamber 7B1 through the concave hole 26 into the rotor side space 26 in the state shown in FIG. things are suppressed. That is, during the opening transition until the end of opening of the intake late closing port 21, the intake late closing port 21 communicates with the rotor side space 26, but the air-fuel mixture flows from the working chamber 7B1 to the rotor side space 26 during the compression stroke. Immediately before the concave hole 25 finishes closing when the amount of inflow increases, the intake late closing port 21 has already finished opening and is no longer communicating with the rotor side space 26, so that the mixture from the rotor side space 26 is This will prevent air from blowing out.

In addition, in order to effectively supply the stratified air-fuel mixture to the working chamber in the latter half of the intake stroke, it is necessary to create a recess on the side opposite to the side where the secondary intake port 18 is provided (on the primary intake port 17 side). It is desirable to provide the hole 25, and the reason for this will be explained with reference to FIG.

FIG. 8 shows a closed transition period CC from the beginning of closing to the end of closing of the primary intake port 17 with respect to the working chamber, a closing transition period DC from the beginning of closing to the end of closing of the secondary intake port 18,
The opening transition period from the beginning of opening to the end of opening of the recessed hole 25 is indicated as AO. As is clear from this figure, the secondary intake port 18 has a closing transition period DC that largely overlaps the transition period AO between the recesses 25 and begins to close before the recesses 25 begin to open with respect to the working chamber. Therefore, if the secondary intake port 18 and the recessed hole 25 are provided in the same side housing, the air-fuel mixture in the rotor side space will escape to the secondary intake port 18 before the recessed hole 25 is opened to the working chamber. It becomes easier. On the other hand, a concave hole 25 is provided in the side housing 3 on the side where the primary intake port 17 is provided, and
If the recessed hole 25 is opened to the working chamber before the primary intake port 17 begins to close to the working chamber, the air-fuel mixture in the rotor side space is effectively fed into the working chamber.

For this reason, the recessed hole 25 is connected to the primary intake port 17.
It is provided in the middle side housing 3 which is the side. In this embodiment, combustion is stabilized due to structural simplification and pumping loss is effectively reduced by the intake late-closing port 21.

FIG. 9 shows a second embodiment of the invention. In the second embodiment, an intake slow closing port 131 is provided in one of the side housings 4 facing each other across the rotor, and a recess 25 is provided in the other side housing 3. That is, the primary intake port and the secondary intake port (not shown in FIG. 9) are arranged in the same manner as in the first embodiment, and the recessed hole 25 is also provided in the intermediate side housing 3 in the same manner as in the first embodiment. However, the intake slow closing ports 31 are provided in the side housings 4 on both sides.
．． 4, and a control valve 33 is provided in the communication path 32.

In this second embodiment as well, while the pumping loss is reduced by the intake late closing port 31, the recessed hole 26 reduces the pumping loss.
The air-fuel mixture is introduced into the rotor side space 26 from the working chamber in the middle of the compression stroke, atomization is promoted within the rotor side space 26, and then the air-fuel mixture is sent to the leading side of the working chamber in the latter half of the intake stroke. The effect of stabilizing combustion is
This is the same as the first embodiment. In this embodiment, the recessed hole 26 and the intake slow closing port 21 are provided in separate side housings 3 and 4 with the rotor 5 in between. The rotor side space 26 does not directly communicate with the intake late closing port 31. For this reason, there is a situation where the air-fuel mixture flowing into the rotor side space 26 through the recessed hole 25 from the working chamber during the compression stroke blows through through the intake late closing port 31.
Definitely prevented.

In addition, although each of the above embodiments shows a case where the present invention is applied to a two-cylinder rotary piston engine, it can also be applied to a three-cylinder or more multi-cylinder rotary piston engine.
In this case as well, for example, as shown in FIG. 10, the intake late closing port 21 and the recessed hole 25 may be disposed in the same side housing in the same manner as in the first embodiment, or the rotor of each cylinder may be disposed in the same manner as in the second embodiment. An intake slow closing port and a recess may be provided in one and the other of the side housings on both sides. In addition, in such a case, as shown in FIG.
5 and a control valve 36 in each communication path 34.
may be provided.

[Effects of the Invention] As described above, according to both the first and second aspects of the invention, pumping loss can be reduced by the intake late closing port provided in the side housing, and
Separately, a recessed hole provided at a predetermined position in the side housing allows the air-fuel mixture to flow into the rotor side space from the working chamber during the compression stroke, promoting atomization of d2 aiki within the rotor side space. By layering the fuel into the leading side of the working chamber, combustion stability under light loads can be improved.

In particular, in the invention according to claim 1, the intake late closing port and the recessed hole are provided in the same side housing, and the timing at which the rotor finishes closing the recessed hole with respect to the working chamber is determined by the opening of the late closing port. By delaying the end of the compression stroke by a predetermined angle, the air-fuel mixture flowing into the rotor side space from the working chamber during the compression stroke is prevented from blowing through through the intake late closing port, reducing pumping loss. and combustion stabilization. Further, according to the invention as set forth in claim 2, by providing the intake late closing port and the recessed hole in separate side housings with the rotor in between, the rotor side space on the side housing side where the recessed hole is located and the intake air Since communication with the late-closing port is avoided, both of the above functions can be achieved satisfactorily.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of a rotary piston engine showing a first embodiment of the present invention, Fig. 2 is a sectional view of the intake port arrangement portion of the rotary piston engine, and Fig. 3 is an intake slow-retardation diagram of the rotary piston engine. 4 to 6 are action explanatory diagrams, FIG. 7 is a timing chart showing the opening/closing relationship between the recessed hole and the intake slow closing port, and FIG. Timing chart showing the opening/closing relationship between the hole, the primary intake port, and the secondary intake port, No. 9
FIG. 10 is a sectional view showing the second embodiment, FIG. 10 is a schematic diagram showing an example of the application to a three-cylinder rotary piston engine, and FIG. 11 is an explanatory diagram showing problems based on the prior art. 1...Casing, 3, 4...Side housing,
5... Rotor, 7... Working chamber, 21.31... Intake slow closing port, 25... Recessed hole.

Claims (1)

[Claims] 1. In the side housing of a rotary piston engine,
In addition to providing an intake late-closing port that is opened and closed by the rotor and closes later than the intake port, it is also opened and closed by the rotor to open from the intake stroke working chamber to the compression stroke working chamber, and to open and close the intake stroke before fully opening and before fully closing the working chamber. An engine pumping loss reduction device having a concave hole that communicates between the working chamber and the rotor side space inside the side seal for a predetermined period of time, wherein the intake late closing port and the concave hole are provided in the same side housing. , the late-closing port and the recessed hole are arranged in such a positional relationship that the timing at which the rotor finishes closing the recessed hole with respect to the working chamber is delayed by a predetermined angle from the timing at which the late-closing port finishes opening. Engine pumping loss reduction device. 2. On the side housing of the rotary piston engine,
In addition to providing an intake late-closing port that is opened and closed by the rotor and closes later than the intake port, it is also opened and closed by the rotor to open from the intake stroke working chamber to the compression stroke working chamber, and to open and close the intake stroke before fully opening and before fully closing the working chamber. An engine pumping loss reduction device that has a concave hole that communicates the working chamber with the rotor side space inside the side seal for a predetermined period of time, and is located on one side of both side housings facing each other with the rotor in between. A pumping loss reduction device for an engine, characterized in that a housing is provided with the intake slow closing port, and the other side housing is provided with the recessed hole.