JP5359268B2 - Rotary piston engine - Google Patents

Description

  The present invention relates to a rotary piston engine, and more particularly to a direct injection type in which fuel is directly injected into a working chamber in an intake or compression stroke.

Conventionally, a triangular rice ball-shaped rotor is accommodated in a bowl-shaped rotor housing having an inner peripheral surface of a tocoloid, and each step of intake, compression, expansion, and exhaust is performed in each of the three working chambers on the outer periphery side along with the rotation A Wankel type rotary piston engine is known. For example, as described in Patent Document 1, it is also possible to arrange a direct injection injector on one side in the long axis direction of the rotor housing and inject fuel directly into the working chamber in the intake or compression stroke. Proposed.
JP-A-6-288249

  However, since a rotary piston engine generally has a weak intake flow in a low rotation range compared to a reciprocating engine, the fuel is directly injected into the working chamber as in the conventional example (Patent Document 1). In the low-load and low-rotation region such as idling, the fuel and intake air are likely to be insufficiently mixed, and the fuel vaporization and atomization are not promoted so much. .

  In this regard, the inventor of the present application made a prototype of an engine in which the fuel injection direction by the direct injection injector is directed to the intake port so that mixing with the intake air is promoted as much as possible, and conducted an experimental study. It has been found that if the fuel is injected when the top of the rotor passes through the injector hole that opens to the inner peripheral surface of the trochoid, the ignition stability in the idling state is dramatically improved.

  In view of the above, the present invention promotes mixing of fuel spray with intake air in a rotary piston engine in which fuel is directly injected into a working chamber in an intake or compression stroke by a direct injection injector. The purpose is to promote atomization and improve the ignition stability of the air-fuel mixture.

  In order to achieve the above object, the invention according to claim 1 of the present application is that the plurality of working chambers partitioned on the outer peripheral side move in the circumferential direction as the rotor accommodated in the housing rotates, respectively, and suck and compress Intended for a rotary piston engine configured to perform expansion and exhaust strokes.

  An injector hole is opened on the inner peripheral surface of the trochoid on the one side in the long axis direction of the rotor housing where the top of the rotor partitions the two working chambers of the intake stroke and the compression stroke, and the working chamber is opened from the opening of the injector hole. When a direct injection injector is provided so as to directly inject fuel, the fuel injection period by the direct injection injector in a predetermined operation state, the period during which the top of the rotor passes through the opening of the injector hole ( It is set to overlap at least partly with the injector hole passage period).

  That is, when a direct injection injector is disposed on one side in the long axis direction of the rotor housing in order to inject fuel into the intake or compression stroke working chamber as in the above-described configuration, the top of the rotor has an intake stroke. Therefore, when the top part of the rotor passes, instantaneously, from the working chamber of the compression stroke through the injector hole, the opening of the rotor is passed through in a state where the working chamber of the compression stroke and the working chamber of the compression stroke are separated. Air is violently ejected into the working chamber of the intake stroke (hereinafter referred to as Spitzback flow).

  Therefore, when fuel is injected at the timing when the top of the rotor passes through the opening of the injector hole as described above, the fuel spray is entrained in the intense Spitzback flow and atomized, and toward the intake side working chamber. Widely distributed. Therefore, for example, even in an operating state where the intake air flow is weak as in idling, the vaporization of the fuel spray can be promoted very effectively, and the ignition stability of the air-fuel mixture can be sufficiently enhanced.

Thus, in order to sufficiently obtain the effect of atomizing the fuel spray by the Spitzback flow and widely dispersing it, the fuel injection period by the direct injection injector is ended before the injector hole passage period at the top of the rotor is ended. In other words, it is preferable to set the end of the fuel injection period to an advance side with respect to the end of the injector hole passage period (claim 1) . This is because the fuel injected after the top of the rotor passes through the opening of the injector hole is not affected by the Spitzback flow.

  On the other hand, the fuel injected before the top of the rotor reaches the opening of the injector hole adheres to the seal member (apex seal) on the top of the rotor, but is peeled off by the intense Spitzback flow generated thereafter, It is blown away to the working chamber on the intake side.

In addition, the fuel injection direction by the direct injection injector is set so as to go from the injector hole opening to the intake port as seen along the axis of the output shaft, and the fuel injection period depends on the rotation of the rotor. Accordingly, it is preferable that the intake port is set so as to overlap at least partly with a predetermined period of the first half of the intake stroke (Claim 2 ). In this way, the intake port starts to open with the rotation of the rotor, and fuel is injected toward the intake flow that flows in at a high speed through a narrow gap. Therefore, the fuel that has been widely dispersed by the Spitzback flow as described above Vaporization and atomization of the spray can be further promoted.

As described above, it is particularly preferable to promote the vaporization and atomization of fuel by using the Spitzback flow in the low load and low rotation region of the engine including idling (claims 3 to 6 ), and the high intake air flow becomes high. In the load or high rotation range, it is better to inject the fuel at a timing at which it collides with the intake flow as efficiently as possible. Therefore, the fuel injection period here is set to start after the passage of the injector hole passage period. (Claim 3 ).

By the way, as described above, when a direct injection injector is disposed on one side in the long axis direction of the rotor housing and fuel is injected from the side closer to the intake port, in the vicinity of the opening of the injector hole so as to avoid interference with this fuel in is preferably centered provided oblong enlarged diameter portion as deviated as the rotor rotational direction delayed side toward the open end (claim 4). In this case, since the opening becomes longer in the rotation direction of the rotor, the period during which the top portion of the rotor passes through the opening is also appropriately increased, and the above-described action by the Spitzback flow is sufficiently obtained.

In addition, the injector hole is preferably provided so that the opening center is positioned on the delay side of the rotor rotation with respect to the long axis of the rotor housing (Claim 5 ), and in this way, the top of the rotor forms the opening of the injector hole. The passing timing is a preferable timing for fuel injection in a predetermined operation region.

  As described above, according to the rotary piston engine of the present invention, when the fuel is directly injected into the working chamber in the intake or compression stroke by the injector, the top of the rotating rotor passes through the opening of the injector hole. In addition, fuel is injected in accordance with the generation of a strong Spitzback flow that is ejected from the compression side working chamber to the intake side working chamber via the injector hole, so that atomization of the fuel spray is promoted and widely dispersed. Thus, the vaporization atomization can be promoted very effectively. Therefore, sufficient ignition stability can be ensured even in a low load and low rotation region such as idling.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the following description of preferable embodiment is only an illustration essentially, and is not intending restrict | limiting this invention, its application thing, or its use.

  FIG. 1 shows a configuration of a main part of a rotary piston engine 1 according to an embodiment of the present invention, in a rotor housing chamber 4 surrounded by a saddle-shaped rotor housing 2 having a trochoid inner peripheral surface 2a and a side housing 3. Contains a generally triangular rice ball-like rotor 6, and three working chambers 5 are defined so as to surround the outer periphery thereof. In this example, the engine 1 is not shown in the figure, but the three side housings 3 and the two rotor housings 2 are alternately overlapped and integrated, and the rotors 6 are respectively provided in two rotor accommodating chambers 4 formed therein. Is a two-rotor type housing.

  The basic shape of the rotor 6 is a peritrochoid inner envelope corresponding to the trochoid inner peripheral surface 2a of the housing, and the outer peripheral surface of the rotor 6 is constituted by three rectangular surfaces each curved slightly outward. A recess 61 is formed on each of the rectangular surfaces, and a seal member 62 (apex seal) is disposed on the top of the rotor, which is the boundary between the rectangular surfaces.

  Although not shown, an internal gear is formed inside the rotor 6. The internal gear meshes with the external gear on the side housing side, and the rotor 6 has an output shaft 7 (eccentric) penetrating the side housing 3. It is supported so as to make a planetary rotational movement with respect to the shaft. That is, the rotational motion of the rotor 6 is defined by the meshing of the internal gear and the external gear, and the rotor 6 is configured so that the apex seal 62 disposed on the top of the rotor 6 is in sliding contact with the trochoid inner peripheral surface 2a. It revolves around its axis X while rotating around the eccentric 7a.

  Then, while the rotor 6 makes one rotation, the three working chambers 5 formed correspondingly between the tops of the rotor 6 move in the circumferential direction and perform the strokes of intake, compression, expansion (combustion), and exhaust. Do. During one rotation of the rotor 6, the output shaft 7 rotates three times. During this time, the three working chambers 5 each perform a combustion cycle once, so that eventually, each rotor 6 has one output shaft 7 for each rotation. Multiple combustion cycles will be performed.

  More specifically, when viewed in the direction of the axis X of the output shaft 7 as shown in the figure, one side in the short axis direction (right side in the figure) of the rotor housing 2 is an area for compression and expansion strokes, and sandwiches the short axis. Thus, the spark plugs 8 and 9 are arranged on the advance side and the delay side in the rotor rotation direction, respectively. The opposite side (left side in the figure) is an intake and exhaust stroke region. In the figure, the working chamber 5 in the intake stroke is connected to the intake port 11 on the upper left side, and the intake air on the upstream side is communicated with the intake port 11. Air is sucked from the passage 12.

  In this embodiment, in order to inject fuel directly into the working chamber 5 in the intake stroke, in this embodiment, one side in the direction in which the long axis (indicated by a dashed line in the drawing) of each rotor accommodating chamber 4 extends, That is, the injector 10 is disposed on the upper side of the drawing. This injector 10 is accommodated in an injector hole 20 formed on the rotor rotation delay side (left side in the figure) with respect to the long axis of the rotor housing 2, and from the opening of the injector hole 20 in the trochoid inner peripheral surface 2 a to the working chamber. The fuel is injected slightly toward the rotor delay side.

  That is, when viewed along the axis X of the output shaft 7 as shown in the figure, the fuel injection direction by the injector 10 is set so as to be directed from the opening of the injector hole 20 toward the intake port 11 and thus injected. In order to avoid interference with the fuel, an elliptical enlarged diameter portion 20b (see FIG. 4) is formed in the vicinity of the opening of the injector hole 20 so that the center of the injector hole 20 is shifted toward the delay side of the rotor rotation toward the opening end. Is provided. Thus, the fuel injected toward the intake port 11 collides with the intake flow, and atomization and dispersion are promoted.

  Thus, the working chamber 5 into which fuel is injected and supplied in the intake stroke moves in the clockwise direction in the drawing as the rotor 6 rotates to enter the compression stroke, and the air-fuel mixture is compressed therein. When the ignition plugs 8 and 9 are ignited at the end of the compression stroke as in the working chamber 5 shown on the right side of the drawing, the air-fuel mixture starts to burn, and the rotor 6 further rotates by receiving this combustion pressure ( Expansion stroke). And if it connects to the exhaust port 13 like the working chamber 5 on the lower left side of the figure, the burned gas is discharged from the exhaust port 13 to the exhaust passage 14 (exhaust stroke).

  As schematically shown in FIG. 2, the ignition by the spark plugs 8 and 9, the fuel injection by the injector 10, and the like are controlled by a control unit 30 (hereinafter abbreviated as ECU). That is, at least signals from the air flow sensor 21 of the intake passage 12, the rotation angle sensor 22 of the output shaft 7, the water temperature sensor 23, the accelerator opening sensor 24, and the like are input to the ECU 30. Based on these inputs, the operating state of the engine 1 is determined, and the ECU 30 determines the fuel injection amount and injection timing by the injector 10, the ignition timing by the spark plugs 8 and 9, and the opening of the throttle valve 25 in the intake passage 12. Etc. are controlled.

  As an example, the ECU 30 controls the fuel injection amount so that the air-fuel ratio of the air-fuel mixture in the working chamber 5 becomes substantially the stoichiometric air-fuel ratio in almost all operation regions of the engine 1 except for the high load region near the full load. . That is, the flow rate of the intake air adjusted by the throttle valve 25 is detected by the air flow sensor 21, and the fuel injection amount by the injector 10 is determined according to the detected value and the engine speed.

  Further, the fuel injection timing is set so that the fuel spray directed toward the intake port 11 collides with a relatively strong intake flow as described above. That is, as shown in FIG. 3 for the change in the intake air flow velocity during the intake stroke, in the engine 1 of this embodiment, the intake port 11 starts to open as shown in FIG. 3 (a) for a while from the intake top dead center (TDC). Then, the flow velocity of the intake air flowing into the working chamber 5 through the narrow gap temporarily increases to show a peak p1, and then once the flow velocity decreases, the moving velocity of the rotor 6 increases, so that the intake air flow velocity again increases. It becomes higher and reaches the second peak p2.

  The first peak appears approximately in the range of BBDC235 to 215 ° Ecc.A when expressed by the rotation angle of the output shaft 7 (Ecsen angle: Ecc.A) with reference to the intake bottom dead center (BDC). In the range of BBDC 240 to 195 ° Ecc. A, the intake air flow velocity becomes considerably high. The second peak p2 appears in the range of approximately BBDC 160 to 140 ° Ecc.A, and the intake flow velocity is relatively high even in the range of BBDC 180 to 130 ° Ecc.A.

  By the way, as shown in FIG. 6A, the top of the rotor 6 that divides the working chamber 5 for the intake stroke (the left side in the drawing) and the working chamber 5 for the compression stroke (the right side in the drawing) is the arrangement of the injector 10. The portion passing through the installed portion (ie, the injector hole 20) is about BBDC 212 to 197 ° Ecc. A between the two peaks p1 and p2 of the intake flow velocity described above, and until that time, the injector 10 is in the compression stroke. The fuel cannot be injected into the working chamber 5 in the intake stroke.

  Therefore, in consideration of the time when the intake air flow velocity becomes high as described above, in this embodiment, fuel is injected by the direct injection injector 10 basically during the period corresponding to the second peak p2. Although illustration is omitted, in this embodiment, an injector is also provided in the intake port 11 and the intake passage 12 on the upstream side thereof, and fuel is also injected by the injector as necessary, and the intake stroke is performed together with air. The working chamber 5 is inhaled.

-Fuel injection timing during idling-
By the way, in general, a rotary piston engine has a weak intake flow in a low rotation range as compared with a reciprocating engine. Therefore, when the fuel is directly injected into the working chamber 5 as in this embodiment, the fuel and the intake air Insufficient mixing. This is the same even when the fuel spray from the injector 10 is directed to the intake port 11 and collides with the intake air flow as described above. For example, in an operation state of low load and low rotation such as during idling. There was a possibility that the ignition stability of the air-fuel mixture would be reduced.

  In order to solve this problem, the inventor of the present application has conceived that the first peak p1 of the intake air flow velocity described above is used, and in the experiment using the prototype engine, the injector 10 as shown in FIG. When the injection timing is advanced to the last timing facing the working chamber 5 of the intake stroke, if the fuel is injected when the top of the rotor 6 just passes through the injector hole 20, the idle stability can be dramatically improved. I found.

That is, in this embodiment, as described above with reference to FIG. 3, the top of the rotor 6, that is, the apex seal 62, passes through the opening of the injector hole 20 in the trochoid inner peripheral surface 2 a. ° Ecc.A period (hereinafter also referred to as injector hole passage period). At this time, as shown in an enlarged view in FIG. 4, the intake side working chamber 5 which is in a negative pressure and the high pressure compression side operation. The chamber 5 is communicated with the injector hole 20 to momentarily generate a strong jet S (hereinafter referred to as “Spitzback flow”) from the compression side to the intake side.

  Then, when the inventors of the present application photographed the state of fuel spraying with the high-speed camera in the above experiment, when the fuel was injected at the timing when the apex seal 62 at the top of the rotor just passed through the injector hole 20 as described above, It was observed that the spray was entrained in the spitzback flow S, the droplets were atomized, and the entire fuel spray was dispersed over a wide range.

  Therefore, in the rotary piston engine 1 according to this embodiment, the tying of the fuel injection by the direct injection injector 10 facing the working chamber 5 in the intake stroke is basically the second in which the flow velocity of the intake air from the intake port 11 increases. Corresponding to the peak p2 of the first half of the intake stroke, for example, in the range of BBDC 180-130 ° Ecc.A, to promote fuel spray dispersion and vaporization atomization by collision with a relatively strong intake flow I have to. In other words, the fuel injection period at this time starts after the elapse of the period during which the top of the rotor 6 (apex seal 62) passes through the opening of the injector hole 20.

  On the other hand, at the time of idling when the intake flow is particularly weak, the fuel injection period by the injector 10 is set so that at least a part thereof overlaps the injector hole passage period, and the above-described Spitzback flow S is effectively used. Thus, atomization and wide dispersion of the fuel spray are promoted, and the vaporization atomization is sufficiently promoted to improve the ignition stability of the air-fuel mixture.

  More specifically, when the fuel injection is started before the injector hole passing period, a part of the injected fuel adheres to the apex seal 65, but is separated by the intense spitzback flow S generated thereafter. Then, it is blown off to the working chamber 5 on the intake side. On the other hand, since the effect of the Spitzback flow S is not exerted on the fuel injected after the passage of the injector hole passage period, the end of the fuel injection period is set to be more advanced than the end of the injector hole passage period. Is preferred.

  In addition, in this embodiment, since the injector hole 20 is opened to the rotor rotation delay side with respect to the long axis of the rotor housing 2 as described above, the timing at which the top of the rotor 6 passes through the opening of the injector hole 20 is as follows. As described above with reference to FIG. 3, this corresponds to the period during which the intake air flow velocity becomes high at the beginning of the intake stroke. By this relatively fast intake flow, the vaporization of the fuel spray atomized and widely dispersed by the Spitzback flow S as described above is further promoted.

  Furthermore, in this embodiment, as described above, an elliptical enlarged diameter portion 20b that is long in the rotation direction of the rotor 6 is provided in the vicinity of the opening of the injector hole 20 so as to avoid interference with the fuel spray. For this reason, while the amount of air flowing out from the compression side working chamber 5 to the intake side working chamber 5 during the injector hole passing period is not so much increased, the injector hole passing period becomes moderately long, and this causes the above-mentioned Spitzback. The action of the flow S can be sufficiently obtained as intended.

  FIG. 5 is a graph of experimental results showing the effect of improving the combustion stability by the Spitzback flow S during idling described above. As shown in the graph of ◯, the engine 1 according to this embodiment has a working chamber. Even if the air-fuel mixture of 5 is leaner than the stoichiometric air-fuel ratio, the rotational fluctuation is very small. On the other hand, the graph of ● is a test conducted on a conventional general port injection rotary piston engine for comparison, and it can be seen that the rotational fluctuation rapidly increases when the air-fuel ratio becomes leaner than the stoichiometric air-fuel ratio. That is, in the engine 1 of this embodiment, the idling stability is remarkably increased as compared with the port injection type in spite of the direct injection type.

  The data in FIG. 5 indicates that the fuel injection is completed when the Aspec seal 62 is near the center in the rotor rotation direction of the opening of the injector hole 20 (BBDC205 ° Ecc. A), as indicated by the solid line in FIG. It is a thing. As shown by the phantom line on the left side of FIG. 4, the injector hole passage period starts at BBDC 212.6 ° Ecc.A. Generally, the fuel injection period at idling is approximately 13-18 ° Ecc.A. Therefore, the data of the above ○ is when the fuel injection starts before the injector hole passing period and ends in the middle of this period.

  Note that the operating region in which fuel is injected at the timing as described above is not limited to idling, but may be expanded to an operating state where the load is slightly higher or the engine speed is higher. Further, if fuel injection is performed in a plurality of times even in an operation region of higher load and higher rotation, any one of them can be performed at the timing as described above.

  Further, in the above-described embodiment, the fuel is injected into the working chamber 5 in the intake stroke by the direct injection injector 10, but the present invention is not limited thereto, and the fuel may be injected into the working chamber 5 in the compression stroke. For example, as shown in FIG. 6, two injectors 10 and 15 are provided side by side in the rotational direction of the rotor 6, and fuel is injected into the working chamber 5 of the intake stroke by one of them, and the working chamber of the compression stroke by the other. 5 may be injected with fuel.

  Alternatively, the fuel may be injected into the working chamber 5 in the intake stroke by both of these two injectors 10 and 15, or the fuel may be injected in the compression stroke with respect to the added injector 15. Even in such a case, if the fuel is injected during the injector hole passing period by at least one of the injectors 10 and 15, the above-described effects of the Spitzback flow S can be obtained.

  The present invention can improve idle stability of a direct injection type rotary piston engine, and is particularly suitable for a vehicle engine.

It is explanatory drawing which shows the principal part structure of an engine. It is a schematic block diagram of a control system. It is explanatory drawing shown by matching with a rotor position about the change of the intake air flow velocity in an intake stroke. When the apex seal of the rotor top to pass through the injector holes are schematically shown to explaining how the Spitz back flow S is produced. It is a graph which shows the improvement of the combustion stability at the time of idling by this invention. It is the FIG. 1 equivalent view which concerns on other embodiment which added one direct injection injector.

DESCRIPTION OF SYMBOLS 1 Rotary piston engine 2 Rotor housing 2a Trochoid inner peripheral surface 5 Actuation chamber 6 Rotor 62 Apex seal (top part of rotor)
7 Output shaft (Eccentric shaft)
10 Injector (direct injection injector)
11 Intake port 15 Additional injector (direct injection injector)
20 Injector hole 20a Expanded portion X near the opening X Center axis of output shaft

Claims (6)

As the rotor accommodated in the housing rotates, a plurality of working chambers partitioned on the outer peripheral side move in the circumferential direction, and perform the intake, compression, expansion, and exhaust strokes. A piston engine,
On the one side in the long axis direction of the rotor housing, the top of the rotor separates the two working chambers of the intake stroke and the compression stroke, an injector hole is opened on the inner surface of the trochoid,
A direct injection injector is provided to inject fuel directly from the opening of the injector hole into the working chamber;
The fuel injection period by the direct injection injector in a predetermined operation state is set so as to overlap at least partly with the injector hole passage period in which the top of the rotor passes through the opening of the injector hole ,
The rotary piston engine , wherein the fuel injection period is set to end before the end of the injector hole passage period . As the rotor accommodated in the housing rotates, a plurality of working chambers partitioned on the outer peripheral side move in the circumferential direction, and perform the intake, compression, expansion, and exhaust strokes. A piston engine,
On the one side in the long axis direction of the rotor housing, the top of the rotor separates the two working chambers of the intake stroke and the compression stroke, an injector hole is opened on the inner surface of the trochoid,
A direct injection injector is provided to inject fuel directly from the opening of the injector hole into the working chamber;
The fuel injection period by the direct injection injector in a predetermined operation state is set so as to overlap at least partly with the injector hole passage period in which the top of the rotor passes through the opening of the injector hole,
The direction of fuel injection by the direct injection injector is set so as to go from the opening of the injector hole to the intake port as seen along the axis of the output shaft,
The fuel injection period by the direct injection injector is set so as to overlap at least partly with a predetermined period in the first half of the intake stroke in which the intake port opens as the rotor rotates.
This is a rotary piston engine. As the rotor accommodated in the housing rotates, a plurality of working chambers partitioned on the outer peripheral side move in the circumferential direction, and perform the intake, compression, expansion, and exhaust strokes. A piston engine,
On the one side in the long axis direction of the rotor housing, the top of the rotor separates the two working chambers of the intake stroke and the compression stroke, an injector hole is opened on the inner surface of the trochoid,
A direct injection injector is provided to inject fuel directly from the opening of the injector hole into the working chamber;
The fuel injection period by the direct injection injector in a predetermined operation state is set so as to overlap at least partly with the injector hole passage period in which the top of the rotor passes through the opening of the injector hole,
It is set so that at least a part of the fuel injection period overlaps the injector hole passage period in the low load and low rotation range,
The fuel injection period in the high load or high rotation range is set to start after the injector hole passage period elapses.
This is a rotary piston engine. As the rotor accommodated in the housing rotates, a plurality of working chambers partitioned on the outer peripheral side move in the circumferential direction, and perform the intake, compression, expansion, and exhaust strokes. A piston engine,
On the one side in the long axis direction of the rotor housing, the top of the rotor separates the two working chambers of the intake stroke and the compression stroke, an injector hole is opened on the inner surface of the trochoid,
A direct injection injector is provided to inject fuel directly from the opening of the injector hole into the working chamber;
The fuel injection period by the direct injection injector in a predetermined operation state is set so as to overlap at least partly with the injector hole passage period in which the top of the rotor passes through the opening of the injector hole,
It is set so that at least a part of the fuel injection period overlaps the injector hole passage period in the low load and low rotation range,
In the vicinity of the opening of the injector hole, the diameter of the injector hole is increased in an elliptical shape so that the center is shifted toward the end of the opening so as to shift toward the rotor rotation direction delay side.
This is a rotary piston engine. As the rotor accommodated in the housing rotates, a plurality of working chambers partitioned on the outer peripheral side move in the circumferential direction, and perform the intake, compression, expansion, and exhaust strokes. A piston engine,
On the one side in the long axis direction of the rotor housing, the top of the rotor separates the two working chambers of the intake stroke and the compression stroke, an injector hole is opened on the inner surface of the trochoid,
A direct injection injector is provided to inject fuel directly from the opening of the injector hole into the working chamber;
The fuel injection period by the direct injection injector in a predetermined operation state is set so as to overlap at least partly with the injector hole passage period in which the top of the rotor passes through the opening of the injector hole,
It is set so that at least a part of the fuel injection period overlaps the injector hole passage period in the low load and low rotation range,
The center of the opening of the injector hole is located behind the major axis of the rotor housing in the rotor rotation direction.
This is a rotary piston engine. 3. The rotary piston engine according to claim 1, wherein at least a part of a fuel injection period overlaps with an injector hole passage period in a low load and low rotation range.

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