JP4888092B2 - 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. .

Then, 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, and a high-temperature burned gas (die The solution gas flows into the working chamber in the intake stroke, and by injecting fuel at this timing, the fuel spray collides with the high-temperature dilution gas, and the vaporization and atomization are sufficiently performed. Can be promoted.
JP-A-7-63063

  However, in recent rotary piston engines, in order to reduce fuel consumption and emissions, the overlap of intake and exhaust is reduced as much as possible. Since vaporization and atomization cannot be promoted, it is difficult to improve the combustibility of the air-fuel mixture.

  In a rotary piston engine, the working chamber formed around the outer periphery of the rotor has a flat shape, and since the distance from the fuel injection valve arranged on the housing side to the outer periphery of the rotor is usually short, it is directed toward the intake port opening. Even if the fuel is injected, a part of the fuel spray tends to adhere to the outer peripheral surface of the rotor, and this also becomes a factor that hinders fuel vaporization and atomization.

  The present invention has been made in view of such various points, and has been devised in the shape of the fuel spray directly injected into the working chamber to promote the vaporization and atomization of the fuel spray by utilizing the intake air flow. It aims at improving the combustibility of air-fuel | gaseous mixture by suppressing wall surface adhesion.

In order to achieve the above object, in the invention of claim 1 of the present application, the first and second fuels are directly injected into the working chamber formed around the outer periphery of the rotor accommodated in the housing. For a fuel injection device of a rotary piston engine provided with an injection valve, the first and second fuel injection valves each inject fuel toward an intake port that opens to the housing, and A multi-hole type in which a plurality of injection holes are provided, and the length of the fuel flow for each injection hole is made different depending on the setting of the length and cross-sectional area of the injection hole. Yes, the length of the fuel jet is shorter in the plurality of nozzle holes in the first fuel injection valve than in the nozzle hole on the side closer to the intake port, Said second fuel injection valve In the plurality of nozzle holes, the length of the fuel jet stream is longer than the nozzle hole on the side closer to the intake port than the nozzle hole on the far side. Injection control means for injecting fuel by the first fuel injection valve when in the predetermined operation region, and for injecting fuel by the second fuel injection valve at a higher load or higher rotation side than the predetermined operation region Is provided .

  That is, when the engine load is low, the charging efficiency of the intake air, that is, the density is low, and the flow velocity of the intake air is low in the low engine speed range. In a predetermined operation region, it is difficult to promote vaporization and atomization of fuel spray using the intake air flow. Therefore, if the penetration of fuel spray is increased at a portion near the intake port at this time, the fuel adheres to the periphery of the intake port opening, that is, to the wall surface of the housing. Thus, the fuel adhering to the wall surface of the housing is discharged without being used for combustion, which directly leads to an increase in fuel consumption and emission.

On the other hand, in the first aspect of the invention, when the engine is in the predetermined operating range, fuel is injected by the first fuel injection valve, and the penetration of fuel spray is relatively weakened at a portion near the intake port ( The penetration of the fuel to the housing wall surface can be suppressed by increasing the penetration on the side where the fuel jet is long and weakening the penetration on the side where the jet is short . At this time, the penetration of the fuel spray near the rotor is relatively strong and the fuel adheres to the outer peripheral surface of the rotor. However, since the fuel injection amount is small in the predetermined operating region where the load is low, the outer periphery of the rotor Thereafter, the fuel adhering to the surface is vaporized and burned, so that fuel consumption and emission are not increased.

On the other hand, in the high load side operation region where the fuel injection amount is larger than that in the predetermined operation region and the high rotation side operation region where the intake air flow is strong, fuel is injected by the second fuel injection valve and fuel spray penetration is achieved. Is relatively strong at the part near the intake port, fuel atomization is promoted by collision with the flow of intake air from the opposite intake port opening, and its vaporization and atomization is effectively promoted. The Further, since the fuel spray penetration is weak at the portion near the rotor, the adhesion of fuel droplets to the outer peripheral surface of the rotor is suppressed. This makes it possible to form a favorable air-fuel mixture and increase its combustibility.

The injection control means performs the fuel injection of the first fuel injection valve when the engine is in a predetermined operating range of low load and low rotation from the intake port as the rotor moves in the first half of the intake stroke. It is preferable that the flow rate of the intake air sucked into the chamber is set within a predetermined period.

By doing so, it is possible to suppress the fuel from penetrating the opposing intake flow and adhering to the vicinity of the opening of the intake port, thereby preventing an increase in fuel consumption and emission.

As described above, according to the fuel injection device for a rotary piston engine according to the present invention, the first and second multi-hole fuel injection valves facing the working chamber inject fuel toward the intake port. The length of the fuel jet is shorter in the plurality of nozzle holes in the first fuel injection valve than in the nozzle hole on the side closer to the intake port. In the plurality of nozzle holes in the fuel injection valve of No. 2, the length of the fuel jet flow is longer than the nozzle hole on the side closer to the intake port, and the engine has a low load. Injection in which fuel is injected by the first fuel injection valve when in a predetermined operation region of low rotation, while fuel is injected by the second fuel injection valve at a higher load or high rotation side than the predetermined operation region Control hand By providing, when the engine is in the predetermined operating region, it suppresses the adhesion of fuel to the housing wall, since a small amount of fuel injection in a low predetermined operating region of a load, fuel adhering to the rotor outer circumference is then Vaporizes and burns, and does not increase fuel consumption or emissions. On the other hand, in a high load side operation region where the fuel injection amount is larger than that in the predetermined operation region and a high rotation side operation region where the intake air flow is strong, the fuel is caused by a collision with the intake air flow from the opposed intake port opening. Atomization is promoted, vaporization and atomization are effectively promoted, and fuel droplets are prevented from adhering to the outer peripheral surface of the rotor, so that a good mixture can be formed and its combustibility is improved. Becomes higher.

  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). These two injectors 30 and 31 are arranged so as to inject fuel toward the opening of the first intake port 11 when viewed in the axial center X direction as shown in FIG. In the fuel spray S1, the penetration of the portion relatively close to the intake port 11 is weaker than the portion relatively close to the rotor 6, and the fuel spray S2 from the second injector 31 is relatively close to the intake port 11. The penetration of the part is relatively stronger than the part closer to the rotor 6.

  Specifically, each of the two injectors 30 and 31 is a multi-hole type provided with a plurality of injection holes for ejecting fuel, and the first injector 30 operates as shown in FIG. For example, eight nozzle holes 30a,..., 30b,... Are arranged in two rows and four at a tip of the injector facing the chamber 5. From these nozzle holes 30a,..., 30b,..., Fuel is ejected at spread angles of about 10 to 20 degrees as shown by broken lines in the figure (hereinafter referred to as individual sprays). A fuel spray S1 is formed as a body.

In the example shown in the drawing, the four nozzle holes 30b,... On the lower side (the side far from the intake port 11 ) are smaller than the four nozzle holes 30a,. ) Is large, the length of the jets ejected from the upper four injection holes 30a,..., That is, the length of the individual sprays is relatively short, and the length of the individual sprays from the lower four injection holes 30b,. The length becomes relatively long. In this way, in the fuel spray S1, the penetration near the intake port 11 is weaker than that near the rotor 6.

Although not shown, eight nozzle holes are arranged in two rows at the tip of the second injector 31 in the same manner as described above, and on the upper side (side closer to the intake port 11) as opposed to the above. The four nozzle holes are larger in diameter than the lower four (the side far from the intake port 11 ). Thus, the penetration of the fuel spray S2 is stronger at the portion near the intake port 11 than at the portion near the rotor 6. In addition to the setting of the nozzle hole diameter (cross-sectional area) as described above, the length of the individual sprays can be adjusted by setting the length thereof, and the penetration strength of the fuel sprays S1 and S2 can be biased. it can.

  As described above, the fuel sprays S1 and S2 from the two injectors 30 and 31 have different penetration biases. As will be described in detail later, it corresponds to the strength of the intake air flow that varies depending on the operating state of the engine 1. Thus, an appropriate air-fuel mixture can be formed. The fuel directly injected into the working chamber 5 from the first and second injectors 30 and 31 is diffused into the working chamber 5 by the intake air flowing from the intake ports 11, 13 and 14, and a good homogeneous air-fuel mixture is obtained. It is 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. , By properly using the two injectors 30 and 31 corresponding to the strength of the flow of the intake air, it is possible to promote the vaporization and atomization of the spray while suppressing the adhesion of the fuel to the wall, thereby forming a favorable mixture Like to do.

  That is, first, when the engine 1 is in the predetermined operating region R1 (shown with a cross hatch in the drawing) in the first operating region (I) on the low speed side, particularly at a low speed and low load, that is, the intake air density. However, if the flow of the intake air is very weak, even if the fuel is injected toward this intake flow, if the penetration is strong, the fuel will penetrate the intake flow and around the intake port opening ( It adheres to the wall of the side housing 3. Thus, the fuel adhering to the wall surface of the housing is discharged without being used for combustion, which directly leads to an increase in fuel consumption and emission.

  Therefore, at this time, the fuel is injected only into the first injector 30 and the fuel spray S1 having a relatively weak penetration near the intake port 11 is used to suppress the adhesion of the fuel to the housing wall as described above. To do. At this time, the penetration of the fuel spray S1 near the rotor 6 is relatively strong and the fuel adheres to the outer peripheral surface of the rotor 6. However, in the first operating region (I), the fuel injection amount is high. Since there are very few fuels, the fuel adhering to the outer peripheral surface of the rotor 6 is then sufficiently vaporized and burned.

  On the other hand, in the region R2 (shown with hatching in the figure) from the high load side to the high rotation side where the fuel injection amount is larger than that in the region R1, and the intake flow becomes stronger, the fuel is supplied only to the second injector 31. The fuel spray S2 has a relatively weak penetration near the rotor 6 to suppress fuel adhesion to the outer peripheral surface of the rotor 6. At this time, the penetration near the intake port 11 is strong, but the atomization of the fuel advances due to the collision with the opposed intake flow, and the vaporization and atomization are effectively promoted, and the fuel adheres to the vicinity of the intake port opening. Is also suppressed.

  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 because if the amount of fuel injection required in response to a high load increases and if the intake air flow increases as the engine speed increases, the fuel sprays S1 and S2 are sufficiently mixed with the intake air. To be promoted.

(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. The fuel can be injected into the working chamber 5 for the first time after A. Therefore, when the vaporization and atomization of the fuel spray is promoted using the intake air flow, a desirable injection timing is within a period including the second peak of the intake air flow velocity (with the movement of the rotor 6 in the first half of the intake stroke). It is within a period when the flow velocity of the intake air is higher than a predetermined value.

  Therefore, in this embodiment, the change in the intake flow velocity in the working chamber 5 is examined in advance by experiments or the like, and the injection period includes the timing at which the second peak occurs, and the injection period, that is, the injection from the start of injection. The injection timing map as shown in FIG. 7 is created so that the intake flow velocity is always 70% or more of the second peak value until the end.

  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.

  In other words, in the first operating range (I), particularly in the low-rotation and low-load region R1, fuel is injected only from the first injector 30, and the fuel spray S1 with relatively weak penetration near the intake port 11 is used. To do. As a result, even if the intake flow is very weak, the adhesion of fuel around the intake port opening can be suppressed.

  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, as in step SA5, the fuel injection timing by the second injector 31 is set based on the injection timing map. Thereafter, the process proceeds to step SA6, and if the set injection timing is reached, the second injector is set. 31 is operated to inject fuel, and then return.

  That is, in the region R2 at a higher load or higher rotation side than the region R1, in consideration of the fact that the fuel injection amount increases and the intake air flow also becomes stronger, only the second injector 31 is injected with fuel. The fuel spray S2 has a strong penetration near the intake port 11. Thus, fuel vaporization and atomization can be effectively promoted by collision with the opposed intake air flow, and fuel adhesion to the outer peripheral surface of the rotor 6 can also be suppressed.

  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 injected by both of the injectors 30 and 31. Let me return, then return.

  That is, even in the first operating region (I), on the high load side where the fuel injection amount is large, by operating both of the two injectors 30 and 31, the injection period is compared to operating only one of them. Becomes shorter, so that the injection pulses of both the injectors 30 and 31 are included in a period higher than a predetermined value of the above-described intake flow velocity, that is, fuel can be injected in a concentrated manner during a period of high intake flow velocity. .

  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 at least in the region R1, and the flow rate of the intake air drawn 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 is greater than or equal to a predetermined value. It is configured so as to be performed within a period during which it becomes high. 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.

  In addition, in the low-load region R1 where the intake air flow is weak, the fuel is injected by the first injector 30 within a period in which the intake air flow velocity becomes higher than a predetermined value as the rotor 6 moves, and the intake port 11 is relatively moved. A fuel spray S1 having a weak penetration at a nearby portion is formed. As a result, it is possible to suppress the fuel from penetrating the opposing intake flow and adhering to the vicinity of the opening of the first intake port 11, thereby preventing an increase in fuel consumption and emission.

  On the other hand, the penetration of the fuel spray S1 near the rotor 6 is relatively strong. However, since the fuel injection amount is very small in the first operating region (I), the amount of fuel adhering to the outer peripheral surface of the rotor 6 is small. Thereafter, the gas is sufficiently vaporized and combusted, and a decrease in combustibility can be suppressed to a minimum.

  Further, in the region R2 on the higher load or high rotation side than the region R1, the amount of fuel adhering to the outer peripheral surface of the rotor 6 increases as the fuel injection amount increases, and the vaporization and atomization tend to be insufficient. As the engine speed increases, the intake flow becomes stronger. Therefore, this time, fuel is injected only into the second injector 31 to form a fuel spray S2 having a relatively strong penetration near the intake port 11 and a weak penetration near the rotor 6.

  In this way, in the portion near the intake port 11 where the fuel spray S2 is strongly penetrating, the vaporization and atomization of the fuel can be effectively promoted by the collision with the opposed intake flow, and the fuel droplets become smaller and the momentum thereof is increased. By decreasing, the penetration becomes weaker, so that the fuel wall surface adhesion can be reduced. Further, since the penetration is originally weak at the portion near the rotor 6, fuel adhesion to the outer peripheral surface of the rotor 6 can be sufficiently suppressed.

  Furthermore, on the high load side (except for the regions R1 and R2) of the first operating region (I), fuel is injected by both of the two injectors 30 and 31, thereby responding to an increase in fuel injection amount and intake air. The fuel can be injected in a concentrated manner during a period during which the flow velocity is high, and fuel vaporization and atomization can be effectively promoted by the intake air flow.

  Furthermore, in the middle and high rotation range above the second operating range (II), intake air is supplied from both the first and second independent intake passages 21 and 22 and is passed through the first and second intake ports 11 and 13. Then, intake air is introduced into the working chamber 5 from both sides. As a result, not only the intake flow rate increases, but also the intake air flows facing each other collide with each other, causing strong turbulence in the working chamber 5 and promoting the vaporization and atomization of the fuel sprays S1 and S2. Air-fuel mixture formation is performed. At this time, fuel is injected from both of the two injectors 30 and 31, and sufficient fuel supply is performed up to a high rotation and high load range.

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, multi-hole type injectors 30 and 31 as shown in FIG. 4 are used, and eight nozzle holes 30a,... However, the number and layout of the nozzle holes are not limited thereto, and various modes are possible although not specifically illustrated .

  Further, in the embodiment, the fuel injection of the first injector 30 in at least the region R1 is performed within a predetermined period in which the intake air flow rate increases with the movement of the rotor 6, but setting of this injection timing is essential. Is not.

  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 a figure which shows typically the layout of the nozzle hole of an injector, and fuel spray. 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.

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

Claims (2)

A fuel injection device for a rotary piston engine in which first and second fuel injection valves are disposed so as to inject fuel directly into a working chamber formed surrounding an outer periphery of a rotor accommodated in a housing,
Each of the first and second fuel injection valves is a multi-hole type in which fuel is injected toward an intake port that opens in the housing, and a plurality of injection holes for ejecting fuel are provided. According to the setting of at least one of the length and the cross-sectional area of the nozzle hole, the length of the fuel jet for each nozzle hole is varied.
In the plurality of nozzle holes in the first fuel injection valve, the length of the fuel jet is shorter than the nozzle hole on the side closer to the intake port,
In the plurality of nozzle holes in the second fuel injection valve, the length of the fuel jet is longer than the nozzle hole on the side closer to the intake port,
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 at a higher load or high rotation side than the predetermined operation region, the second fuel injection valve is used. A fuel injection device for a rotary piston engine, comprising injection control means for injecting fuel. The fuel injection device according to claim 1.
The injection control means performs the fuel injection of the first fuel injection valve when the engine is in a predetermined operating range of low load and low rotation from the intake port 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 configured to be performed within a period in which a flow rate of intake air sucked into the chamber is higher than a predetermined value.

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