JP4811256B2 - Fuel injection device for rotary piston engine - Google Patents

Description

  The present invention relates to a rotary piston engine in which fuel is directly injected into a working chamber, and particularly relates to measures for promoting vaporization and atomization of fuel spray using intake air flow.

  Conventionally, as a rotary piston engine of this type, as disclosed in, for example, Patent Document 1, a high-temperature dilution gas that flows from a working chamber in an exhaust stroke to a working chamber in an intake stroke is used. There are known ones that promote vaporization and atomization of spray. In this device, the intake port is opened on the inner peripheral surface of the trochoid of the housing surrounding the outer periphery of the rotor (so-called peripheral port), and the fuel injection valve is arranged so as to inject fuel toward the intake port opening. .

When the top (apex) of the rotor passes through the intake port opening, the working chamber in the exhaust stroke and the working chamber in the intake stroke are communicated with each other through the intake port (overlap of intake and exhaust). High-temperature burned gas (dilution gas) flows into the working chamber in the intake stroke. By injecting fuel at this timing, the fuel spray collides with the high-temperature dilution gas. Vaporization and atomization can be sufficiently promoted.
JP-A-7-63063

  By the way, in the rotary piston engine currently put into practical use for automobiles, for example, in order to reduce fuel consumption and emission, the intake port is usually opened on the side surface of the housing where the side surface of the rotor is in sliding contact (so-called side port). In this opening, there is no overlap between the intake and exhaust as in the conventional example, so that the vaporization and atomization of the fuel cannot be promoted using the dilution gas.

  In addition, the flow of the intake air flowing into the working chamber from the intake port that opens in the side surface of the housing changes its direction in the moving direction of the rotor after flowing into the working chamber (see arrow F in FIG. 4). At this time, if the inertia of the intake flow from the intake port opening is small, the flow will change direction immediately after entering the working chamber ((a) in the figure), while the inertia of the intake flow is large. In this case, the flow changes direction while greatly wrapping around in the working chamber ((b) in the figure).

  As a result, the main flow of the intake air flow in the working chamber in the moving direction of the rotor passes closer to the intake port opening on the low load and low rotation side where the inertia of the intake air flow is relatively small, while the inertia of the intake air flow is reduced. On the relatively large, high-load, high-rotation side, it passes through the opposite side of the intake port opening, so it is not easy to make fuel spray collide with this mainstream.

  The present invention has been made in view of the above points, and the object of the present invention is to focus on the fact that the flow field of the intake air changes depending on the operating state of the engine as described above. By changing the direction, it is to maximize the fuel vaporization and atomization by the intake air flow.

  In order to achieve the above object, according to the first aspect of the present invention, the intake port opens on the side surface of the housing that faces the working chamber and the side surface of the rotor is in sliding contact, and the fuel is directly injected into the working chamber. For a fuel injection device of a rotary piston engine provided with possible fuel injection means, the fuel injection means is arranged close to the intake port opening in the rotor width direction when the engine is in a predetermined operating region of low load and low rotation. On the other hand, the fuel is injected in the direction opposite to the above in the rotor width direction at a higher load or higher rotation side than the predetermined operation region.

  With the above structure, when fuel is injected by the fuel injection means into the working chamber in the intake stroke during the operation of the engine, the fuel spray is caught in the flow of the intake air and diffused, and the fuel droplets are vaporized and fogged. The fuel vapor is mixed with the intake air to form an air-fuel mixture. At this time, since the inertia of the intake air flow is relatively small in a predetermined operation region of low load and low rotation, the intake air flowing into the working chamber from the intake port opening in the side surface of the housing immediately goes in the moving direction of the rotor. The main flow passes near the intake port opening in the rotor width direction.

  Further, since the inertia of the intake air flow is relatively higher at a higher load or higher rotation side than the predetermined operation region, the intake air flows into the working chamber as a strong jet from the intake port opened on the side surface of the housing. After proceeding to near the side of the housing on the opposite side, the direction is changed in the moving direction of the rotor while largely turning around. Therefore, the main flow of the intake air flow in the working chamber passes through the opposite side of the intake port opening in the rotor width direction.

  In response to such a change in the flow field of the intake air, the fuel injection means injects fuel closer to the intake port opening in the rotor width direction in the predetermined operation region of low load and low rotation, while higher load than that. On the high rotation side, the fuel is injected in the direction opposite to the intake port opening in the rotor width direction. The fuel spray injected in this way collides with the main flow of the intake air flow regardless of the change in the flow field as described above, so that fuel atomization, vaporization, and atomization are effectively promoted.

  As the fuel injection means for changing the injection direction as described above, specifically, a first fuel injection valve that faces the working chamber on the inner surface of the trochoid of the housing and injects fuel near the intake port opening in the rotor width direction. And a second fuel injection valve that injects fuel in the direction opposite to the above in the rotor width direction, and when the engine is in a predetermined operating region of low load and low rotation, fuel is injected by the first fuel injection valve, An injection control means for injecting fuel with the second fuel injection valve on a higher load or higher rotation side than the predetermined operation region may be provided.

  In this way, the fuel injection direction can be changed in response to a change in the operating state of the engine by properly using the first and second fuel injection valves. Also, if the first fuel injection valve used on the relatively low load side has a smaller capacity than the second fuel injection valve used on the high load side, the injection accuracy can be increased even when the fuel injection amount is small. easy.

  In this case, it is preferable that the first fuel injection valve used in the predetermined operation region of low load and low rotation as described above is disposed on the delay side with respect to the moving direction of the rotor relative to the second fuel injection valve. Item 3). In other words, when the engine load is low, the intake charging efficiency, that is, the density is low, and the flow rate of the intake air is low at low engine speeds. It is desirable to inject the fuel as soon as possible so that the intake air flow is not attenuated in the room.

  Therefore, as described above, the first fuel injection valve is disposed relatively behind the moving direction of the rotor, that is, at a position relatively facing the working chamber that becomes the intake stroke as the rotor moves. For example, the fuel can be injected relatively quickly by the first fuel injection valve, and the fuel spray can collide before the intake flow is attenuated so much.

  It is particularly preferable that the timing of fuel injection by the first fuel injection valve is set within a period in which the flow rate of the intake air drawn from the intake port into the working chamber becomes higher than a predetermined value as the rotor moves in the first half of the intake stroke. (Claim 5). In this way, the vaporization and atomization of the fuel spray can be further effectively promoted by the collision with the high-speed intake flow. In addition, the fuel droplets become smaller and their momentum decreases, so that the fuel spray penetration is weakened and the adhesion to the wall surface is reduced. In addition, it is preferable to perform not only the first fuel injection valve but also the fuel injection from the second fuel injection valve within the above-described period if possible.

  Also, a first intake port that opens on one side of the housing and is always open, and a second intake port that opens on the other side of the housing and is opened at a higher rotation side than the predetermined operation region are provided. Preferably, the first fuel injection valve injects fuel closer to the first intake port opening, and the second fuel injection valve is closer to the opposite side (that is, closer to the second intake port opening). The fuel is injected, and after the second intake port is opened, the fuel is injected by both the fuel injection valves.

  In this way, in the predetermined operation region of low load and low rotation and the operation region of higher load or high rotation side and until the second intake port is opened, as in the first and second aspects of the invention. In addition to obtaining the action, the intake air is supplied from the first intake port only to the working chamber until the second intake port is opened. It is easy to promote fuel vaporization and atomization by the intake air flow.

  On the other hand, if the second intake port is opened, the intake air flows into the working chamber from both sides together with the first intake port, so that the main flow of the intake flow is not deviated and the intake flow rate is increased. Since the flow itself becomes stronger, by injecting fuel from both the first and second fuel injection valves at this time, it is possible to cope with an increase in the required fuel injection amount, and injection from only one of them. Compared to this, the fuel can be widely dispersed in the rotor width direction, which is advantageous for forming a favorable air-fuel mixture.

  As described above, according to the fuel injection device for a rotary piston engine according to the present invention, when the engine is in a predetermined operation region of low load and low rotation, while fuel is injected near the intake port opening in the rotor width direction, By injecting fuel in the opposite direction on the higher load or high rotation side, the fuel injection direction is changed in response to the change in the flow field of the intake air, and the fuel spray collides with the main flow of the intake air flow. The fuel can be effectively atomized, vaporized and atomized.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that the following description of the preferred embodiment is merely illustrative in nature, and is not intended to limit the present invention, its application, or its use.

(Entire engine configuration)
FIG. 1 shows a configuration of a main part of a rotary piston engine 1 according to an embodiment of the present invention, and is schematically shown in a rotor housing chamber 4 surrounded by a bowl-shaped rotor housing 2 having a trochoid inner peripheral surface 2a and a side housing 3. A triangular rotor 6 is accommodated, and three working chambers 5, 5, and 5 are formed on the outer peripheral side thereof. As shown in FIG. 2, the engine 1 is formed by integrating two rotor housings 2, 2 so as to be sandwiched between three side housings 3, 3, 3, and two rotor housing chambers 4 formed therebetween. 4 is a two-rotor type in which rotors 6 and 6 are accommodated respectively.

  Hereinafter, in this embodiment, the side housing 3 (shown in FIG. 1) positioned between the two rotor housings 2 and 2 is referred to as an intermediate housing 3 in distinction from those at both ends.

  An internal gear (not shown) is formed inside the rotor 6, and the internal gear meshes with the external gear on the side housing 3 side, and the rotor 6 penetrates the intermediate housing 3 and the side housing 3. The eccentric shaft 7 (hereinafter also simply referred to as the shaft 7) is supported so as to make a planetary rotational movement.

  That is, the rotational movement of the rotor 6 is defined by the meshing of the internal gear and the external gear, and the rotor 6 has a seal portion disposed at each of the three tops of the outer periphery sliding on the trochoidal inner peripheral surface 2 a of the rotor housing 2. While rotating, the shaft 7 revolves around the axis X of the shaft 7 while rotating around the eccentric ring 7 a. And, while the rotor 6 makes one rotation, the working chambers 5, 5,. A stroke is performed, and the rotational force generated thereby is output from the shaft 7 via the rotor 6.

  More specifically, when viewed in the direction of the axis X of the shaft 7 as shown in FIG. 1, one side (left side in the illustrated example) of each rotor accommodating chamber 4 is generally an intake and exhaust stroke region. The opposite side (the right side in the figure) is generally the region of compression and expansion strokes. In the figure, the working chamber 5 (the upper left working chamber in the figure) communicating with the first intake port 11 is in the latter half of the intake stroke, and this working chamber 5 moves clockwise in the figure as the rotor 6 rotates. When the process proceeds to the compression stroke, the air-fuel mixture is compressed inside. Thereafter, as in the working chamber 5 shown on the right side of the figure, the ignition plugs 9 and 10 are ignited at a predetermined timing from the final stage of the compression stroke to the expansion stroke, and the combustion / expansion stroke is performed.

  The intermediate housing 3 has a pair of first intake ports 11 and 11 (only one is shown in FIG. 1) so as to communicate with the working chamber 5 in the intake stroke in the two rotor accommodating chambers 4 and 4 on both sides. Similarly, a pair of first exhaust ports 12 and 12 (only one is shown in FIG. 1) are formed so as to communicate with the working chambers 5 and 5 in the exhaust stroke, respectively. On the other hand, the side housing 3 is formed with second and third intake ports 13 and 14 so as to communicate with the working chamber 5 in the intake stroke, respectively, and communicates with the working chamber 5 in the exhaust stroke. Thus, the second exhaust port 15 is formed.

  The first, second, and third intake ports 11, 13, and 14 constitute downstream end portions of the intake passage 16 that supplies intake air to the working chamber 5 in the intake stroke of each rotor accommodating chamber 4. ing. That is, as shown in FIG. 3, the intake passage 16 branches into three for each rotor accommodating chamber 4 and communicates with the three intake ports 11, 13, and 14, respectively. Is changed in accordance with the operating state of the engine 1 so that the intake air can be efficiently charged over the entire operating region from the low load low rotation to the high load high rotation.

  FIG. 3 schematically shows the overall structure of the intake and exhaust system by dividing one of the two rotor accommodating chambers 4 and 4 (the front side in FIG. 2) into two schematically. The left side of the figure shows the intermediate housing 3 side as in FIG. 1, and the right side of the figure shows the side housing 3 side.

  As shown in FIG. 3, an air cleaner 17 and an air flow sensor 18 are disposed upstream of the intake passage 16, while the downstream side of the intake passage 16 branches into two passages 19, 20. The passage 19 is further divided into two independent intake passages 21 and 22 on the downstream side. The downstream end of the first independent intake passage 21 communicates with the first intake port 11, and the downstream end of the second independent intake passage 22 communicates with the second intake port 13. Further, the downstream end of the other passage 20 communicates with the third intake port 14.

  An electric throttle valve 23 that is driven by a stepping motor or the like and adjusts the cross-sectional area of the passage is disposed in the intake passage 16 before branching as described above. It comes to adjust. A shutter valve 24 is provided in the second independent intake passage 22 and is driven by an electromagnetic pneumatic actuator 25 that uses the negative pressure of the intake passage 16 to fully close the second independent intake passage 22. Or either fully open.

  Further, although not shown, a rotary valve driven by an actuator is disposed at the downstream end of the other passage 20, and only intake air is supplied by the first and second independent intake passages 21 and 22. Then, the intake air is supplied only in a predetermined high rotation state where the intake air amount is insufficient (hereinafter, this passage 20 is referred to as an additional intake passage 20).

  1 and 3, reference numeral 26 denotes a catch tank that collects a part of the blow-by gas blown through from the side surface of the rotor 6. The blow-by gas collected here is blown by a blow-by gas passage 27 shown only in FIG. 3. It is introduced into the intake passage 16.

  In this embodiment, fuel is directly injected into the working chamber 5 into which intake air is introduced by the intake system as described above, that is, the working chamber 5 in the intake stroke. First and second injectors 30 and 31 (fuel injection valves) are arranged facing one side (upper side in FIG. 1). The two injectors 30, 31 respectively face the rotor accommodating chamber 4 from the trochoid inner peripheral surface 2 a of the rotor housing 2, and the first injector 30 is arranged on the delay side with respect to the moving direction of the rotor 6 relative to the second injector 31. Has been.

  Further, when viewed in the direction of the axial center X as shown in FIG. 1, the two injectors 30 and 31 are arranged so as to inject fuel toward the first and second intake ports 11 and 13, respectively. As is apparent from one side in the long axis direction (upper side in FIG. 1) as shown in FIG. 4, the first injector 30 injects fuel closer to the opening of the first intake port 11 in the width direction of the rotor 6. In addition, the second injector 31 injects fuel toward the opposite side of the rotor width direction, in other words, toward the opening of the second intake port 13.

  In order to inject fuel in such a way as to be offset in the rotor width direction, the axial centers of the injectors 30 and 31 may be inclined, but the direction of the injection hole formed at the tip of the injector is the axis of the injector. You may make it incline from. In this embodiment, as an example, a multi-hole type in which a plurality of nozzle holes are provided at the tip is used, and the direction of each nozzle hole is inclined with respect to the injector axis. The injector may be a well-known swirler type or a slit type.

  As described above, the fuel sprays S1 and S2 from the two injectors 30 and 31 have different directions, as will be described in detail later, but the flow of intake air that changes according to the operating state of the engine 1 (FIG. ) And (b) (see arrow F)), for the purpose of performing a more appropriate mixture formation. In other words, in this engine 1, by properly using the two injectors 30 and 31, the fuel spray collides with the main flow regardless of the change in the flow field of the intake air, and its vaporization and atomization are promoted to achieve good homogeneity. An air-fuel mixture is formed and ignited and burned.

  Burned gas generated by such combustion is discharged from the working chamber 5 that has shifted to the exhaust stroke to the passage in the exhaust manifold 33 via the first and second exhaust ports 12 and 15. In the exhaust manifold 33, the exhaust from the two rotor accommodating chambers 4, 4 is collected and flows out to the exhaust pipe 34 on the downstream side. The exhaust manifold 33 is provided with an O2 sensor 35 for detecting the oxygen concentration in the exhaust gas, and the exhaust pipe 34 is provided with two catalytic converters 36 and 37 for purifying the exhaust gas. The O2 sensor 35 is used for feedback control of the fuel injection amount by the injectors 30 and 31.

  Although only shown in FIG. 3, reference numeral 38 denotes an electromagnetic rotation angle sensor (eccentric angle sensor) that is disposed on one end side of the eccentric shaft 7 and detects its rotation angle. Reference numeral 39 denotes a water temperature sensor that detects the temperature state of the cooling water (engine water temperature) facing a water jacket (not shown) formed inside the rotor housing 2.

(Outline of engine control)
The ignition circuit of the spark plugs 9 and 10, the motor of the throttle valve 23, the actuator 25 of the shutter valve 24, the injectors 30 and 31 and the like are controlled by a control unit 40 (hereinafter abbreviated as ECU). At least the output signal of the air flow sensor 18, the output signal of the O 2 sensor 35, the output signal of the eccentric angle sensor 38, and the output signal of the water temperature sensor 39 are input to the ECU 40, and further from the accelerator opening sensor 41. A signal is input. The ECU 40 determines the operating state of the engine 1 (for example, engine load and engine speed), and controls the fuel injection amount, injection timing, ignition timing, etc. for each working chamber 5 of each rotor 6 accordingly. In addition, the route through which the intake air flows is switched.

  That is, first, the fuel injection amount is controlled so that the air-fuel ratio of the air-fuel mixture in the working chambers 5, 5,. This is because the flow rate of intake air adjusted by the throttle valve 23 is detected by the air flow sensor 18, and the fuel injection amounts by the injectors 30 and 31 are determined according to the detected value and the engine rotational speed. In the high load region near the load, the control may be made to be richer than the stoichiometric air-fuel ratio. However, the present invention is not limited to this, and the control can be performed so that the stoichiometric air-fuel ratio becomes the entire operating region.

  Further, the opening / closing states of the shutter valve 24 of the second independent intake passage 22 and the rotary valve of the additional intake passage 20 are switched mainly corresponding to the engine speed, and the intake circulation path is switched in three ways. That is, as shown in an example of the control map in FIG. 5, the shutter valve 24 has a low engine speed ne1 (for example, 3000 rpm) or less in a low engine speed range (the first operating range (I) shown). At this time, since the rotary valve is also closed, the intake air flows from the first independent intake passage 21 through the first intake port 11 and flows into the working chamber 5.

  When the engine rotational speed ne exceeds the first set rotational speed ne1, the shutter valve 24 is fully opened, and intake air flows from the first and second independent intake passages 21, 22 through the first and second intake ports 11, 13. Then, it flows into the working chamber 5 from both sides thereof (the second operation area (II) shown in the figure). The rotary valve is also opened in the high speed range (the third operating range (III) shown in the figure) in which the engine speed ne exceeds the second set speed ne2 (for example, 6500 rpm), and an additional intake passage is provided in the working chamber 5. The intake air also flows in from the 20 and the third intake port 14.

  Further, as a feature of the present invention, in this embodiment, the shutter valve 24 is closed as described above, and the first operating region (I) on the low rotation side where the intake air is supplied to the working chamber 5 only from the first intake port 11. , The flow field of the intake air changes depending on the operating state of the engine 1, and the first and second injectors 30 and 31 are used correspondingly and the fuel injection direction is changed accordingly. The fuel vaporization and atomization can be promoted to the maximum.

  First, when the engine 1 is in the predetermined operation region R1 (shown with a cross hatch in the drawing) in which the engine 1 is also in the first operation region (I) on the low rotation side, particularly at low rotation, the intake air density is low. Since the flow velocity is low, when the inertia of the intake air flow becomes small, the air flows into the working chamber 5 from the first intake port 11 opened on the side surface of the intermediate housing 3 as schematically shown in FIG. The intake flow F immediately moves in the moving direction of the rotor 6, and the main flow passes near the opening of the first intake port 11 in the rotor width direction.

  On the other hand, since the inertia of the intake air flow is relatively large in the region R2 (shown with hatching) on the higher load or high rotation side than the region R1, as schematically shown in FIG. After the intake flow F flows into the working chamber 5 from the opening of the first intake port 11 and flows into the working chamber 5 and advances to near the side of the housing on the opposite side, the direction of movement of the rotor 6 is changed while greatly turning around. become. Therefore, the main flow of the intake air flow F in the working chamber 5 passes through the rotor width direction opposite to the opening of the first intake port 11 (closer to the opening of the second intake port 13).

  The two injectors 30 and 31 are selectively used for such a change in the flow field of the intake air. In the region R1, fuel is injected near the opening of the first intake port 11 by the first injector 30, while in the region R2, the first fuel is injected. By injecting fuel in the direction opposite to the above by the two injectors 31, each fuel spray S1, S2 collides with the main flow of the intake air flow F, and fuel atomization, vaporization, and atomization are effective. Promoted.

  In addition, from the relatively high load side operation region of the first operation region (I) excluding the two regions R1 and R2 to the second and third operation regions (II) and (III) of medium and high rotations. , Fuel is injected by both the first and second injectors 30 and 31. This is to cope with an increase in the required fuel injection amount and to disperse the fuel widely in the rotor width direction. The fuel injected in this way becomes stronger as the engine speed increases. And get mixed well.

(Fuel injection control)
Below, the specific procedure of the control which uses two injectors 30 and 31 properly as mentioned above is demonstrated based on the flowchart of FIG. This control is executed at a predetermined timing synchronized with the ignition timing for each of the working chambers 5, 5,.

  First, in step SA1 after the start, various signals from the air flow sensor 18, the O2 sensor 35, the exhaust angle sensor 38, the accelerator opening sensor 41, and the like are read. In the subsequent step SA2, the engine 1 enters the first operating range (I). Determine if there is. This determination is made with reference to the control map of FIG. 5 based on the engine rotation speed calculated based on the signal from the eccentric angle sensor 38, and if it is determined as NO that is not in the first operating range (I), it will be described later. On the other hand, if it is determined YES in the first operating range (I), the process proceeds to step SA3.

  In step SA3, it is determined whether or not the vehicle is in the low rotation and low load region R1 in the first operating region (I). If the determination is NO and the region is not R1, the process proceeds to step SA7, which will be described later. If YES in step S4, the flow advances to step SA4 to set the first injector 30 as the injector to be used. Further, in consideration of the flow rate characteristic of the first injector 30, the injection pulse width for obtaining the target fuel injection amount is determined. The target fuel injection amount is calculated so as to be the target air-fuel ratio with respect to the intake charging efficiency ce calculated based on the output (intake flow rate) of the air flow sensor 18 and the engine speed. .

  Subsequently, in step SA5, the fuel injection timing by the first injector 30 is set based on an injection timing map as shown in FIG. The injection timing map experimentally obtains in advance optimal injection timings corresponding to the engine load (for example, intake charging efficiency ce) and the engine speed, that is, the operating state of the engine 1, for each of the first and second injectors 30 and 31. As shown schematically in the figure, the injection pulse is included in a period in which the flow velocity of the intake air is higher than a predetermined value.

  Referring to FIG. 8, in the rotary piston engine 1 of this embodiment, when any of the working chambers 5 is at an eccentric angle of 270 ° before bottom dead center (BBDC 270 ° Ecc. A) ( When the intake stroke starts from (a)) and then the first intake port 11 starts to open as shown in (a) in the figure, the flow velocity of the intake air flowing into the working chamber 5 through the narrow gap shows the first peak p1. Then, after the intake port opening is increased and the flow velocity is once reduced, the moving speed of the rotor 6 is increased, whereby the BBDC 180 to 140 ° Ecc. Within the range of A, the intake flow velocity reaches the second peak p2.

  Here, in the engine 1 of this embodiment, the BBDC 190 ° Ecc. Up to A, the first and second injectors 30 and 31 do not face the working chamber 5 in the intake stroke, and BBDC 190 ° Ecc. For the first time after A, the first injector 30 is ready to inject fuel into the working chamber 5. Therefore, the injection timing desirable for colliding the fuel spray from the first injector 30 with the intake air flow and promoting the vaporization and atomization is within a period including the second peak of the intake air flow velocity (the first half of the intake stroke). In the period when the flow velocity of the intake air becomes higher than a predetermined value as the rotor 6 moves.

  Therefore, in this embodiment, the change in the intake air flow velocity at the portion where the fuel spray S1 from the first injector 30 is formed in the working chamber 5 is examined in advance through experiments or the like, and the timing at which the second peak occurs is injected. The injection timing as shown in FIG. 7 is included so that the intake flow velocity is always 70% or more of the second peak value during the injection period, that is, from the start of injection to the end of injection. A map (map for the first injector 30) is created.

  After setting the fuel injection timing of the first injector 30 in step SA5 based on the injection timing map in which appropriate injection timing is set as described above, the process proceeds to step SA6 and the signal from the eccentric angle sensor 38 is set. Thus, the position of the working chamber 5 in the intake stroke (position based on the exhaust angle) is detected. When the set injection timing comes, the first injector 30 is operated to inject fuel, and then the process returns.

  That is, in the first operating region (I), particularly in the region R1 of low rotation and low load, fuel is injected only from the first injector 30 and relatively closer to the intake port 11 as shown in FIG. An incoming fuel spray S1 is formed. The fuel spray S1 collides with the main flow of the intake flow F that passes relatively closer to the first intake port 11, and the atomization, vaporization, and atomization thereof are effectively promoted.

  On the other hand, in step SA7, which is determined by not being in the region R1 (NO) in step SA3, it is determined whether or not the region is in the region R2 on the higher load or high rotation side, and this determination is NO. For example, while the process proceeds to step SA10 described later, if it is the region R2 (YES), the process proceeds to step SA8, the second injector 31 is set as the injector to be used, and the injection pulse width is determined in consideration of the flow rate characteristics. .

  Subsequently, in step SA9, the fuel injection timing by the second injector 31 is set based on the injection timing map as in step SA5. In this injection timing map, as in the case of the first injector 30, the change in the intake air flow velocity at the portion where the fuel spray S2 from the second injector 31 is formed in the working chamber 5 is examined in advance through experiments or the like. The injection timing is set a little later than the first injector 30 in accordance with the intake air flow F that largely circulates in the working chamber 5.

  If the injection timing is set, the process proceeds to step SA6. If it is determined that the set injection timing is reached based on the signal from the eccentric angle sensor 38, the second injector 31 is operated to inject fuel. And then return.

  That is, in the region R2 on the higher load or high rotation side than the region R1, the fuel flows only to the second injector 31 in response to the intake air flow F greatly flowing in the working chamber 5 and passing closer to the second intake port 13. As shown in FIG. 4B, a fuel spray S2 directed toward the second intake port 13 is formed. Thereby, the fuel spray S2 collides with the main flow of the intake air flow F in the same manner as in the region R1, and the atomization, vaporization, and atomization can be effectively promoted.

  Further, in step SA10, which is determined to be NO in steps SA2 and SA7, both the first and second injectors 30 and 31 are set, and the injection pulse width is set in consideration of their respective flow characteristics. To decide. In the subsequent step SA11, as in steps SA5 and SA9, the injection timings of the first and second injectors 30 and 31 are set from the injection timing map, and the process proceeds to step SA6. Fuel is supplied from both of the injectors 30 and 31. Inject, and then return.

  By operating both the two injectors 30 and 31 in this way, it becomes possible to inject fuel required in a relatively high load operation state in a relatively short period of time, and compare the fuel sprays S1 and S2. Since it can be formed when the static intake flow velocity is high, it is advantageous in promoting the vaporization and atomization. In particular, in the middle and high rotation range beyond the second operating range (II), the intake air flows into the working chamber 5 through the first and second intake ports 11 and 13 from both sides, and the operations of both injectors 30 and 31 are performed. As a result, the fuel spray widely dispersed in the rotor width direction is caught in the intake air flow and is sufficiently mixed.

  6 as a whole, when the engine 1 is in a predetermined operation region (region R1) of low load and low rotation, fuel is injected by the first injector 30, while higher load or higher rotation side is injected. In the region R2, it corresponds to the injection control means 40a for injecting fuel by the second injector 31.

  The injection control means 40a performs the fuel injection of the first injector 30 in the region R1 so that the flow rate of the intake air sucked into the working chamber 5 from the first intake port 11 with the movement of the rotor 6 in the first half of the intake stroke exceeds a predetermined value. It is configured so as to be performed within a period during which the price increases. Such a function of the injection control means 40a is realized by the CPU executing a program stored in the memory of the ECU 40.

(Function and effect)
Therefore, in the rotary piston engine 1 according to this embodiment, first, the shutter valve 24 of the second independent intake passage 22 is closed in the first operating region (I) on the low rotation side, and intake air is supplied to the first independent intake passage 21. Only when the flow rate of the intake air is small, the flow velocity can be increased and the intake air flow in the working chamber 5 can be strengthened. Therefore, it is advantageous in promoting vaporization and atomization of the fuel spray by the intake air flow.

  In particular, in the low-load low-rotation region R1, fuel is injected by the first injector 30 within a period in which the intake air flow rate becomes higher than a predetermined value as the rotor 6 moves, and the first intake port 11 is closer to the rotor width direction. On the other hand, in the region R2 on the higher load or higher rotation side than that, the fuel is injected by the second injector 31 to form the fuel spray S2 opposite to the above in the rotor width direction. By doing so, the fuel sprays S1 and S2 collide with the main flow of the intake air flow in the working chamber 5 regardless of changes in the operating state of the engine 1, and the atomization, vaporization, and atomization are effectively promoted. Can do.

  Further, in the middle / high rotation range from the high load side (except for the regions R1 and R2) to the second and third operation regions (II) and (III) of the first operation region (I), the two injectors 30 and 31 By injecting fuel from both, it is possible to cope with an increase in the fuel injection amount and to inject fuel during a period of relatively high intake flow velocity, and to promote vaporization and atomization by the intake air flow. Become advantageous.

  In particular, if the shutter valve 24 is opened and the intake air flows through both the first and second independent intake passages 21 and 22 and flows into the working chamber 5 from both sides, both the injectors 30 and 31 Fuel injected so as to be widely dispersed in the rotor width direction can be entrained in the intake air flow and sufficiently mixed, which is also advantageous in promoting fuel vaporization and atomization.

  In addition, the structure of this invention is not limited to the thing of the said embodiment, Other various structures are included. That is, in the above-described embodiment, the first and second injectors 30 and 31 are selectively used to change the direction of fuel injection into the working chamber 5. However, the present invention is not limited to this. By making the assist air supply direction variable in the assist type injector, the direction of fuel injection into the working chamber 5 can be changed by one injector, as in the case of changing the fuel injection direction.

  However, if the two injectors 30 and 31 are used properly as in the above embodiment, the first injector 30 used on the relatively low load side has a smaller capacity than the second injector 31 used on the high load side. By setting it as the thing, the precision of the injection control in area | region R1 with few fuel injection amounts can be raised, and it is preferable.

  Moreover, in the said embodiment, although the 1st, 2nd two injectors 30 and 31 are arrange | positioned at some intervals, you may arrange | position both close. However, it is preferable to arrange the first injector 30 used on the low load side relatively on the delay side in the moving direction of the rotor 6 as in the above-described embodiment. This is because the fuel is injected as soon as possible so that the intake flow is not attenuated, and also because it is disposed relatively close to the opening of the intake port 11.

  Further, in the above-described embodiment, the engine 1 has the additional intake passage 20, and supplies intake air from the additional intake passage 20 in addition to the first and second independent intake passages 21 and 22 in a high speed region where the intake amount is large. However, the additional intake passage 20 may not be provided.

  As described above, the rotary piston engine according to the present invention can promote the vaporization and atomization of the fuel to be injected directly into the working chamber and increase the combustibility of the air-fuel mixture. Suitable for engines and the like.

It is sectional drawing which shows the principal part structure of the rotary piston engine which concerns on embodiment of this invention. It is a perspective view of the principal part of the engine. It is a whole block diagram including the control system of the engine. It is explanatory drawing which shows typically the fuel spray injected from the two injectors in the rotor width direction. It is explanatory drawing which shows an example of the control map of an engine. It is a flowchart figure of the control which uses an injector properly. It is explanatory drawing which shows an example of an injection time map. It is explanatory drawing which shows the change of the intake flow velocity accompanying the change of an eccentric angle.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rotary piston engine 2 Rotor housing 2a Trochoid inner peripheral surface 3 Side housing, intermediate housing 5 Working chamber 6 Rotor 11 First intake port 13 Second intake port 30 First injector (first fuel injection valve)
31 Second injector (second fuel injection valve)
40 Control unit (ECU)
40a Injection control means S1, S2 Fuel spray

Claims (5)

A fuel injection device for a rotary piston engine in which an intake port is opened on a side surface of a housing facing the working chamber, and fuel injection means capable of directly injecting fuel is provided in the working chamber,
The fuel injection means injects fuel closer to the intake port opening in the width direction of the rotor when the engine is in a predetermined operation region of low load and low rotation, while at a higher load or higher rotation side than the predetermined operation region. A fuel injection device for a rotary piston engine, wherein the fuel is injected in a direction opposite to the above in the rotor width direction. The fuel injection device according to claim 1.
The fuel injection means
A first fuel injection valve that faces the working chamber on the inner circumferential surface of the trochoid of the housing, injects fuel near the intake port opening in the rotor width direction, and injects fuel in the direction opposite to the above in the rotor width direction. Two fuel injectors;
When the engine is in a predetermined operation region of low load and low rotation, fuel is injected by the first fuel injection valve, while fuel is injected by the second fuel injection valve at a higher load or high rotation side than the predetermined operation region. And a fuel injection device for a rotary piston engine. The fuel injection device according to claim 2, wherein
The fuel injection device for a rotary piston engine, wherein the first fuel injection valve is disposed on the delay side with respect to the moving direction of the rotor relative to the second fuel injection valve. The fuel injection device according to claim 2, wherein
A first intake port that opens on one side of the housing and is always open; and a second intake port that opens on the other side of the housing and is opened on the higher rotation side than the predetermined operation region;
The fuel injection device for a rotary piston engine, wherein the injection control means is configured to inject fuel by both the first and second fuel injection valves after the second intake port is opened. The fuel injection device according to claim 1.
The fuel injection timing that the fuel injection means injects closer to the intake port opening in the rotor width direction is a period in which the flow rate of the intake air drawn from the intake port into the working chamber becomes higher than a predetermined value as the rotor moves in the first half of the intake stroke A fuel injection device for a rotary piston engine, wherein the fuel injection device is set inside.

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