JP2010156289A - Fuel injection control device of rotary piston engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize especially low fuel consumption in a partial load operation area while increasing torque in a heavy load operation area. <P>SOLUTION: The rotary piston engine 1 is constituted by housing a rotor 2 which partitions the rotor holding chamber 31 into three working chambers 8 and which performs each of the strokes of intake, compression, expansion, and exhaust in order while moving each of the working chambers 8 circumferentially by making planetary rotational movements about an output shaft X. The rotary piston engine 1 is provided with a first fuel injection valve 15 and a second fuel injection valve 16. The first fuel injection valve 15 directly injects fuel into the working chamber 8 which is in an intake stroke, and the second fuel injection valve 16 directly injects fuel into the working chamber 8 which is in a compression stroke. A control means 100 performs intake stroke injection by the first fuel injection valve 15 when the operating condition of the engine 1 is in the heavy load operation area, and performs fuel injection during the intake stroke by the first fuel injection valve 15 and fuel injection during the compression stroke by the second fuel injection valve 16 when the operating condition of the engine 1 is in the partial load operation area. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The technology disclosed herein generally relates to a fuel injection control device for a rotary piston engine.

  The rotary piston engine is an engine in which a substantially triangular rotor is accommodated in a rotor accommodating chamber formed by disposing side housings on both sides of a rotor housing having a substantially elliptical trochoid inner peripheral surface. As the rotor rotates, the rotary piston engine causes each of the three working chambers partitioned between the rotor and the housing to move in the circumferential direction, and sequentially performs intake, compression, expansion, and exhaust strokes (for example, Patent Documents). 1).

  The fuel supply in such a rotary piston engine is generally performed by injecting fuel from a fuel injection valve attached to an intake port and / or an intake manifold.

Further, in Patent Document 1, in order to form a stratified mixture around the spark plug, the fuel injection valve disposed near the major axis so as to face the working chamber in the intake stroke is directed toward the spark plug. Thus, a rotary piston engine in which fuel is directly injected into the working chamber at a timing after the latter half of the intake stroke is also disclosed.
JP-A-6-288249

  By the way, when the operation state of the rotary piston engine is in the high load operation region, high torque is required. On the other hand, when the operation state of the rotary piston engine is in the partial load operation region, lower fuel consumption is required than the torque request. The However, the present applicant has found that the conventional rotary piston engine is difficult to satisfy both of these requirements.

  The fuel injection control device for a rotary piston engine disclosed herein aims to improve the torque in the high load operation region, while achieving particularly low fuel consumption in the partial load operation region.

  The applicant of the present application has at least two fuel injections: a first fuel injection valve that directly injects fuel into the working chamber in the intake stroke, and a second fuel injection valve that directly injects fuel into the operating chamber in the intake or compression stroke. A valve is provided, and the fuel injection mode by the first and second fuel injection valves is changed according to the operating state of the rotary piston engine.

  Specifically, when the operation state of the rotary piston engine is in a predetermined high-load operation region, fuel injection during the intake stroke (hereinafter also referred to as intake stroke injection) is performed by the first fuel injection valve. While the intake air is cooled by the vaporization latent heat effect and the intake charge efficiency is increased to improve the torque, when the operation state of the rotary piston engine is in the partial load operation region, the intake stroke injection and the first injection by the first fuel injection valve are performed. (2) Fuel injection during the compression stroke by the fuel injection valve (hereinafter also referred to as compression stroke injection) is performed so as to homogenize the air-fuel mixture in the working chamber and improve fuel consumption by improving combustion characteristics. .

  A fuel injection control device for a rotary piston engine is partitioned by a rotor housing having a substantially elliptical trochoid inner peripheral surface defined by a long axis and a short axis perpendicular to each other, and a side housing arranged so as to sandwich the rotor housing. The rotor is accommodated in the rotor accommodating chamber to divide the three working chambers, and by rotating the planets around the output shaft, the rotor is moved in the circumferential direction, and the intake, compression, A rotary piston engine configured to perform each of the expansion and exhaust strokes in order, and a fuel that is attached to the rotor housing so as to face the working chamber in the intake stroke and directly into the working chamber in the intake stroke A first fuel injection valve that injects, and the rotor facing the working chamber in the intake or compression stroke A second fuel injection valve which is attached to the wing and directly injects fuel into the working chamber in the intake or compression stroke, and an air-fuel ratio in which the air-fuel mixture in the working chamber is set according to the operating state of the rotary piston engine Control means for controlling fuel injection by the first and second fuel injection valves so that at least one of the side housings communicates with the working chamber in the intake stroke and When the intake port is opened so that air can be sucked into the working chamber, and the operating means of the rotary piston engine is in a predetermined high load operating region, the first fuel injection valve The fuel is injected during the intake stroke of the rotary piston engine, and the operation state of the rotary piston engine is in a partial load operation region where the load is lower than the high load operation region. Sometimes, it is configured to perform the fuel injection during the compression stroke and fuel injection during the intake stroke by the first fuel injection valve according to the second fuel injection valve.

  When the operation state of the rotary piston engine is in a predetermined high load operation region, intake stroke injection is performed by the first fuel injection valve. The intake stroke injection cools the intake air by the effect of latent heat of vaporization of the fuel and increases the intake charge efficiency. As a result, the torque is improved in the high load operation region. On the other hand, when the operation state of the rotary piston engine is in the partial load operation region, intake stroke injection by the first fuel injection valve and compression stroke injection by the second fuel injection valve are performed. In addition to the effect of improving the charging efficiency due to the intake air cooling, the fuel injection during the intake stroke ensures the vaporization atomization time for a long time because the fuel is injected at a much earlier timing than the ignition timing. . Therefore, the intake stroke injection by the first fuel injection valve is advantageous in forming an air-fuel mixture with good vaporization atomization.

  The air-fuel mixture supplied with fuel through the first fuel injection valve shifts from the intake stroke to the compression stroke as the rotor rotates. At this time, the flow of the air-fuel mixture (fuel) is relatively delayed with respect to the rotation of the rotor, and as a result, in the compression / expansion operation chamber having a flat shape in the rotation direction of the rotor, the advance side of the rotor rotation direction is relatively This region becomes lean, and inhomogeneity occurs such that the region on the delay side in the rotor rotation direction becomes relatively rich. Fuel injection by the second fuel injection valve is performed in the compression stroke. This fuel injection can enrich the relatively lean region in the working chamber and eliminate the heterogeneity of the air-fuel mixture. Eliminating the heterogeneity of the air-fuel mixture can improve the combustion characteristics of the rotary piston engine, and the improvement of the combustion characteristics can improve the fuel consumption.

  The rotary piston engine includes at least one spark plug that is attached to the rotor housing so as to face the working chamber in the compression or expansion stroke, and the first and second fuel injection valves are respectively long in the rotor housing. The first fuel injection valve is disposed in the vicinity of the shaft, and when viewed in the output shaft direction, the first fuel injection valve directs fuel in the direction of the intake port, and the second fuel injection valve The fuel may be injected in the direction of the spark plug when viewed in the axial direction.

  Since the first fuel injection valve injects the fuel from the vicinity of the long axis of the rotor housing toward the intake port, the spray flight distance becomes relatively long, which is advantageous in suppressing the fuel wall surface adhesion.

  Since the second fuel injection valve injects fuel from the vicinity of the long axis of the rotor housing toward the spark plug, the fuel is supplied to the region on the advance side in the rotational direction of the rotor in the working chamber in the compression stroke. This is advantageous. That is, by supplying fuel to a relatively lean area, the area can be enriched, which is effective in eliminating the heterogeneity of the air-fuel mixture in the working chamber.

  When the operation state of the rotary piston engine is in the partial load operation region, the control means is configured to perform fuel injection during the intake stroke by the first fuel injection valve and during the compression stroke by the second fuel injection valve. It may be configured to further perform the preceding injection by the second fuel injection valve at a timing between the fuel injection.

  In the pre-injection, since fuel is injected into the working chamber at a timing earlier than the compression stroke injection, the vaporization atomization time is secured, and the vaporization atomization ratio of the fuel is increased accordingly. This is advantageous in achieving homogenization of the air-fuel mixture in the working chamber. In addition, by injecting the fuel into three parts at different timings with the rotation of the rotor, the concentration distribution in the working chamber that is flat in the rotation direction of the rotor can be controlled more finely.

  The fuel injection timing during the intake stroke by the first fuel injection valve is set to overlap with the timing when the intake port is open, and the timing of the preceding injection by the second fuel injection valve is determined by the working chamber. The fuel injection timing during the compression stroke may be set when the working chamber is in the middle of the compression stroke, while the fuel injection timing during the compression stroke is set when the time is from the latter half of the stroke to the beginning of the compression stroke. .

  At the opening timing of the intake port, intense intake flow is formed in the working chamber. Injecting the fuel at this timing, that is, performing the intake stroke injection is advantageous for efficiently diffusing the fuel and homogenizing the air-fuel mixture. On the other hand, by executing the compression stroke injection in the middle of the compression stroke, the fuel can be efficiently supplied to a relatively lean region in the compression working chamber in relation to the rotation angle of the rotor.

  The fuel injection control means is further controlled by the control means and further includes a third fuel injection valve for injecting fuel into the intake port, and the control means has a predetermined high operating state of the rotary piston engine. When in the rotational operation region, at least both fuel injection into the intake port by the third fuel injection valve and fuel injection during the intake stroke by the first fuel injection valve may be executed.

  The rotary piston engine has a feature that the maximum rotational speed is relatively high and the operation range is relatively wide. For this reason, combining the fuel injection into the working chamber by the first and second fuel injection valves with the port injection is effective in a rotary piston engine having a wide operating range.

  The rotary piston engine may be configured such that an air-fuel ratio set in the high load operation region and an air-fuel ratio set in the partial load operation region are different from each other.

  When the air-fuel ratio is relatively low and the amount of fuel to be supplied is relatively large, a long vaporization atomization time is ensured by performing the intake stroke injection. Further, since the amount of fuel to be supplied is relatively large, the fuel concentration is relatively high even in the relatively lean region in the working chamber described above, and the combustion characteristics are not deteriorated even with only the intake stroke injection. . On the other hand, when the air-fuel ratio is relatively high and the amount of fuel to be supplied is relatively small, the fuel mixture is divided into intake stroke injection and compression stroke injection to inject the fuel in the working chamber as described above. To improve combustion characteristics.

  As described above, the fuel injection control device of the rotary piston engine performs the intake stroke injection by the first fuel injection valve when the operation state is in the predetermined high load operation region, thereby improving the intake charging efficiency by the intake air cooling. As a result of the improvement, while the torque is improved, when the operation state is in the partial load operation region, the intake stroke injection by the first fuel injection valve and the compression stroke injection by the second fuel injection valve are performed, thereby mixing in the working chamber. It is possible to eliminate the inhomogeneity of the gas and improve the fuel consumption by improving the combustion characteristics.

  Hereinafter, a fuel injection device for a rotary piston engine will be described with reference to the drawings. In addition, the following description is only an illustration essentially and does not intend restrict | limiting an application thing or a use.

  1 and 2 show an example of a rotary piston engine 1 (hereinafter also simply referred to as engine 1). The engine 1 is of a two-rotor type having two rotors 2 and 2, and the two rotor housings 3 and 3 on the front side and the rear side sandwich an intermediate housing (side housing) 4 therebetween. These are integrated by being sandwiched between two side housings 5 and 5 from both sides. In FIG. 1, a part of the right side (front side) is cut away to show the inside, and the left side (rear side) side housing 5 is also separated to show the inside. In addition, a symbol X in the figure is a rotation axis (output shaft) that is an axial center of the eccentric shaft 6.

  And the trochoid inner peripheral surfaces 3a and 3a drawn by parallel trochoid curves of the rotor housings 3 and 3, inner side surfaces 5a and 5a of the side housings 5 and 5 sandwiching the rotor housings 3 and 3 from both sides, and intermediate As shown in FIG. 2, the rotor accommodating chamber 31 having a substantially elliptical shape as a ridge as seen from the direction of the rotation axis X has two front side and rear side two inner side surfaces 4 a and 4 a on both sides of the housing 4. One rotor 2 is accommodated in each of the rotor accommodating chambers 31. Each rotor accommodating chamber 31 is arranged symmetrically with respect to the intermediate housing 4 and has the same configuration except that the position and phase of the rotor 2 are different. Therefore, hereinafter, one rotor accommodating chamber 31 is provided. Will be described.

  The rotor 2 is formed of a substantially triangular block body in which the central portion of each side bulges when viewed from the direction of the rotation axis X, and three substantially rectangular flank surfaces 2a, 2a are formed on the outer periphery between the top portions. , 2a. A recess 2b extending in the major axis direction is formed at the center of each flank surface 2a.

  The rotor 2 has apex seals (not shown) at the respective tops, and these apex seals are in sliding contact with the trochoid inner peripheral surface 3a of the rotor housing 3, and the trochoid inner peripheral surface 3a of the rotor housing 3 and the intermediate housing 4 The inner side surface 4a, the inner side surface 5a of the side housing 5, and the flank surface 2a of the rotor 2 define three working chambers 8, 8, and 8 inside the rotor accommodating chamber 31, respectively. Therefore, the engine 1 has a total of six working chambers, ie, first to third three working chambers 8 on the front side and fourth to sixth three working chambers 8 on the rear side ( (See FIG. 7).

  A phase gear is provided inside the rotor 2 (not shown). That is, the internal gear (rotor gear) inside the rotor 2 and the external gear (fixed gear) on the side housing 5 mesh with each other, and the rotor 2 is connected to the eccentric shaft 6 that penetrates the intermediate housing 4 and the side housing 5. On the other hand, it is supported to make a planetary rotation.

  That is, the rotational motion of the rotor 2 is defined by the meshing of the internal gear and the external gear, and the rotor 2 has an eccentric wheel of the eccentric shaft 6 while the three seal portions are in sliding contact with the trochoid inner peripheral surface 3a of the rotor housing 3, respectively. (Eccentric shaft) Revolving around the rotation axis X in the same direction as the rotation while rotating around the eccentric shaft 6a (including rotation and revolution, simply referred to as rotation of the rotor). Then, the three working chambers 8, 8, and 8 move in the circumferential direction while the rotor 2 makes one rotation, and intake, compression, expansion (combustion), and exhaust strokes are performed in each of them, and are generated thereby. A rotational force is output from the eccentric shaft 6 via the rotor 2.

  More specifically, in FIG. 2, the rotor 2 rotates clockwise as indicated by an arrow, and the left side of the rotor storage chamber 31 is separated by the long axis Y of the rotor storage chamber 31 passing through the rotation axis X. Is generally the region for the intake and exhaust strokes, and the right side is generally the region for the compression and expansion strokes.

  When attention is paid to the upper left working chamber 8 in FIG. 2, this shows an intake stroke in which an air-fuel mixture is formed by the intake air and the injected fuel (hereinafter, the working chamber in this state is referred to as the intake working chamber 8). When the working chamber 8 shifts to the compression stroke as the rotor 2 rotates, the air-fuel mixture is compressed therein (not shown, but hereinafter, the working chamber in this state is referred to as the compression working chamber 8). Say). Thereafter, as in the working chamber 8 shown on the right side of FIG. 2, the ignition plugs 91 and 92 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 (hereinafter referred to as this state). A working chamber is also referred to as a compression / expansion working chamber 8). Then, when the exhaust stroke such as the lower left working chamber 8 in FIG. 2 is reached (hereinafter, the working chamber in this state is also referred to as the exhaust working chamber 8), after the combustion gas is exhausted from the exhaust port 10, Returning to the intake stroke again, each stroke is repeated.

  A plurality of intake ports 11, 12, 13 communicate with the intake working chamber 8. That is, the first intake port 11 is opened on the inner side surface 4 a of the intermediate housing 4 facing the intake working chamber 8 near the short axis Z on the outer peripheral side of the rotor accommodating chamber 31. Further, as shown in FIG. 1, the inner side surface 5 a of the side housing 5 facing the intake working chamber 8 is close to the short axis Z on the outer peripheral side of the rotor accommodating chamber 31 so as to face the first intake port 11. The second intake port 12 and the third intake port 13 are open. For example, in the low rotation range of the engine 1, intake is performed only from the first intake port 11, and when the intake amount becomes insufficient, intake is also performed from the second intake port 12 (medium rotation range), and the intake amount is further insufficient. Then, the intake air is also taken from the third intake port 13 (high rotation range), and the optimum intake flow velocity is maintained even if the intake amount changes, and the entire operation from the low load low rotation to the high load high rotation of the engine 1 is maintained. The air can be efficiently sucked in across the area.

  A plurality of exhaust ports 10 and 10 communicate with the exhaust working chamber 8. That is, the exhaust port 10 is opened on the inner side surface 4 a of the intermediate housing 4 facing the exhaust working chamber 8 near the short axis Z on the outer peripheral side of the rotor accommodating chamber 31. As shown in FIG. 1, the exhaust port 10 is also opened on the inner surface 5 a of the side housing 5 facing the exhaust working chamber 8 so as to face the exhaust port 10. As described above, the engine 1 employs a so-called side exhaust system, and the opening position and the opening shape of the exhaust port 10 are set so that the intake open timing and the exhaust open timing do not overlap. . As a result, the residual exhaust gas brought into the next stroke is reduced, and as a result, the combustion stability is improved even when the air-fuel mixture is lean.

  A first injector (fuel injection valve) 15 and a second injector 16 are attached near the top of the rotor housing 3 corresponding to the long axis Y of the rotor housing 3. The first injector 15 is disposed facing the intake working chamber 8, and the second injector 16 is disposed facing the compression working chamber 8.

  As shown in FIGS. 2 and 3, the first injector 15 is arranged on the delay side in the rotor rotation direction with respect to the long axis Y, that is, on the left side in FIG. 3. The first injector 15 is configured to inject fuel directly into the intake working chamber 8, and the first injector 15, particularly when viewed in the direction of the rotation axis X shown in FIG. Fuel is injected from the vicinity of the top toward the intake ports 11, 12, 13. The first injector 15 is a multi-hole type having a plurality of injection holes for injecting fuel at the tip thereof. Here, as shown in FIG. 4, the first injector 15 has a total of eight directions (D1-1, D1-2, D2-1, D2) including four directions in the rotor rotation direction and two directions in the rotor width direction. Eight injection holes are formed so as to inject fuel into (-2, D3-1, D3-2, D4-1, D4-2). The number of nozzle holes of the first injector 15 is not limited to this. FIG. 4 shows the spray positions of the fuel injected from the injectors 15 and 16 on a virtual plane that is separated from the tip positions of the first and second injectors 15 and 16 by a predetermined distance. Double circles indicate the axial positions of the first and second injectors 15 and 16 projected onto the virtual plane, respectively. In addition, the injection direction of the 1st injector 15 shown to FIG.3, 4 is an illustration, and is not limited to this.

  As shown in FIGS. 2 and 3, the second injector 16 is disposed on the leading side in the rotor rotation direction with respect to the long axis Y, that is, on the right side in FIG. 3. The second injector 16 is configured to inject fuel directly into the intake or compression working chamber 8, and the second injector 16 is particularly suitable for the rotor housing when viewed in the direction of the rotation axis X shown in FIG. 3. The fuel is injected from the vicinity of the top of 3 toward the spark plug 91 described later. Similarly to the first injector 15, the second injector 16 is a multi-hole type having a plurality of injection holes for injecting fuel at the tip thereof. Here, the second injector 16 is, as shown in FIG. Two injection holes are formed so as to inject fuel in one direction with respect to the rotor rotation direction and in two directions with respect to the width direction of the rotor. By injecting fuel in two directions with respect to the width direction of the rotor, it is possible to avoid spraying directly on the plug hole of the spark plug 91. In addition, the injection direction of the 2nd injector 16 shown to FIG.3, 4 is an illustration, and is not limited to this. Here, the first and second injectors 15 and 16 may employ the same injector as the main body, but may be different from each other only in the plate on which the nozzle hole attached to the tip is formed.

  As shown in FIG. 3, the first and second injectors 15 and 16 are respectively attached to the rotor housing 3 so that the axial directions thereof are parallel to each other. Here, in FIG. 3, the axial centers of the first and second injectors 15 and 16 are arranged so as to have a predetermined angle with respect to the long axis Y, but the first and second injectors are arranged. The angle at which 15 and 16 are disposed is not particularly limited. The arrangement angle of the first and second injectors 15 and 16 may be set as appropriate so that the angle formed between the direction of the fuel injected from the tip and the axis is optimum. Although not shown, first and second injectors 15 and 16 are provided for each of the two rotor housing chambers 31 on the front side and the rear side. The first and second injectors 15 and 16 are disposed so as to be parallel to each other. Therefore, in this engine 1, as shown in FIG. 5, a total of four injectors 15 and 16 are arranged so as to be parallel to each other. In FIG. 5, the illustration of the side housings 5 and 5 in the engine 1 is omitted.

  As shown in FIGS. 3 and 5, the injectors 15 and 16 are connected to the accumulator 7, and the accumulator 7 is connected to a high-pressure fuel pump (not shown). The accumulator 7 stores the fuel supplied from the high-pressure fuel pump in a high-pressure state so that the fuel can be supplied to the injectors 15 and 16 at an arbitrary timing. The pressure accumulator 7 includes a first fuel supply pipe 71 and a second fuel supply pipe 72. The first fuel supply pipe 71 includes a first injector 15 attached to the front rotor housing 3 (right rotor housing 3 in FIG. 5) and a rear rotor housing 3 (left rotor housing 3 in FIG. 5). Rotation axis X direction (precisely, a direction inclined by a predetermined angle with respect to the rotation axis X) across the front and rear rotor housings 3 so as to communicate with the second injector 16 attached to each other It is arrange | positioned so that it may extend. The second fuel supply pipe 72 has a front side and a rear side so that the second injector 16 attached to the front rotor housing 3 and the first injector 15 attached to the rear rotor housing 3 communicate with each other. Is disposed so as to extend in the direction of the rotation axis X (more precisely, a direction inclined by a predetermined angle on the opposite side of the rotation axis X from the first fuel supply pipe 71). ing. The first and second fuel supply pipes 71 and 72 intersect at a substantially central position in the length direction, and communicate with each other at the intersecting position. Thus, the pressure accumulator 7 is configured to have an X shape when viewed in plan view.

  In this configuration, the distances between the four injectors 15 and 16 through the fuel supply pipes 71 and 72 can be made substantially equal to each other. This is effective in suppressing variations in fuel injection amount errors in the injectors 15 and 16. That is, when fuel is injected from a certain injector 15, 16, the pulsation accompanying the fuel injection propagates through the fuel supply pipes 71, 72 and reaches the other injectors 15, 16. The transmission of pulsation may affect the fuel injection of the injectors 15 and 16. For example, when the distance between the injectors 15 and 16 is different, the influence of pulsation is relatively large between the injectors 15 and 16 having a relatively short distance, and between the injectors 15 and 16 having a relatively long distance. The influence of pulsation becomes relatively small. The magnitude of the influence of such pulsation causes the magnitude of the error in the fuel injection amount in each of the injectors 15 and 16. On the other hand, when the distances between the injectors 15 and 16 are made equal, the influences of pulsation become equal to each other, so that the fuel injection amount errors in the injectors 15 and 16 become equal. That is, variation in fuel injection amount error in each of the injectors 15 and 16 is suppressed.

  As shown in FIG. 3, each of the first and second fuel supply pipes 71 and 72 protrudes downward at both ends, and is connected to the upper ends of the first or second injectors 15 and 16. 73. As described above, since the four injectors 15 and 16 are arranged in parallel to each other, the connecting portions 73 and the injectors 15 and 16 are aligned, and the connecting portions 73 are connected to the injectors 15 and 16. If the pressure accumulator 7 is pushed in so as to be fitted on the upper end of the injector, all of the injectors 15 and 16 can be connected to the pressure accumulator 7 at a time. The pressure accumulator 7 is separately fixed to the rotor housing 3. Thus, the structure which integrated the 1st and 2nd fuel supply pipes 71 and 72 is effective in simplifying the structure of the pressure accumulator 7, making it easy to assemble.

  One end (the right end in FIG. 5) of the first fuel supply pipe 71 is closed, while the other end (the left end in FIG. 5) is opened for drilling when the pressure accumulator 7 is manufactured. A blind plug 74 is attached to the opening to ensure airtightness and liquid tightness. One end (the right end in FIG. 5) of the second fuel supply pipe 72 is also closed, while the other end (the left end in FIG. 5) is opened for drilling, and this opening has a high-pressure fuel pump. An end portion 75 of the connecting pipe connected to is attached.

  In the pressure accumulator 7, a fuel pressure sensor 76 is attached at a position where the first and second fuel supply pipes 72 intersect. The fuel pressure sensor 76 measures the fuel pressure in the accumulator 7, and outputs the measurement signal to a control unit 100 (hereinafter abbreviated as ECU) described later (see FIG. 6). The ECU 100 uses the fuel pressure signal when setting the pulse width (fuel injection signal) to be supplied to the injectors 15 and 16. In this configuration, the distance between the fuel pressure sensor 76 and each of the injectors 15 and 16 is substantially equal to each other. This suppresses variations in the injectors 15 and 16 with respect to the measured value of the fuel pressure sensor 76.

  Although not shown in the drawings, in the pressure accumulator 7 having the above-described configuration, the fuel pressure sensor 76 is not attached to the intersection of the first and second fuel supply pipes 71 and 72 but is attached to the other end of the first fuel supply pipe 71. A fuel pressure sensor 76 may be attached. This configuration has the advantage of minimizing the seal portion in the accumulator 7.

  As shown in FIG. 2, a third injector 17 that injects fuel into the intake port 11 is attached near the first intake port 11 so as to face the first intake port 11.

  In addition, at the side of the rotor housing 3, the trailing side (lagging side) position and the leading side (leading side) position in the rotor rotation direction across the short axis Z are respectively set to the T side spark plug 91 and the L side. A spark plug 92 is attached. These two spark plugs 91 and 92 face the compression / expansion working chamber 8 and ignite the air-fuel mixture in the compression / expansion working chamber 8 simultaneously or sequentially with a phase difference. By providing the two spark plugs 91 and 92 in this manner, the combustion speed is increased in the compression / expansion working chamber 8 having a flat shape.

  FIG. 6 shows a configuration related to the control of the rotary piston engine 1. The ECU 100 controls the operation of the first to third injectors 15, 16, 17, the ignition circuits of the T-side and L-side ignition plugs 91, 92, the motor of the throttle valve 107, and the like. For this ECU 100, at least an air flow sensor 105 for detecting the intake flow rate taken into the intake passage, a linear O2 sensor 106 for detecting the oxygen concentration in the exhaust, and an eccentric angle sensor for detecting the rotational angle of the eccentric shaft 6. 103, a water temperature sensor 104 that detects a temperature state of the cooling water (engine water temperature), an accelerator opening sensor 101, an engine speed sensor 102, and a fuel pressure sensor 76 each output a signal. The ECU 100 determines the operating state of the engine 1, and according to the operating state, the opening of the throttle valve 107, the ignition timing by the T-side and L-side spark plugs 91 and 92 in each working chamber 8, the first Control of the fuel injection amount and fuel injection timing by the third injectors 15, 16, and 17 is performed. Further, when the engine 1 is started, the ECU 100 drives the starter motor 108.

  Here, as shown in FIG. 10, the engine 1 is operated in a low rotation low load region (lower left region in FIG. 10), a low rotation high load region (upper left region in FIG. 10), and high rotation. It is divided into four regions, a low load region (lower right region in FIG. 10) and a high rotation high load region (upper right region in FIG. 10). In each region, the first to third injectors 15, 16, The fuel injection modes according to 17 are different from each other. With regard to the classification of this operation region, a relatively low load region (low rotation / low load region and high rotation / low load region) and a relatively high load region (low rotation / high load region and high rotation / high load region) The air-fuel ratio is set to be different from each other. That is, the boundary line between the relatively low load region and the relatively high load region is determined by the air-fuel ratio.

  Thus, in the low rotation and low load region, the ECU 100 performs the intake stroke injection in which the fuel is injected into the working chamber 8 in the intake stroke by the first injector 15 and the working chamber 8 in the compression stroke by the second injector 16. In the low rotation and high load range, the ECU 100 executes only the intake stroke injection by the first injector 15 and in the high rotation and low load range, the ECU 100 The ECU 100 executes three fuel injections, namely, an intake stroke injection by the first injector 15, a compression stroke injection by the second injector 16, and a port injection by the third injector 17. The two fuel injections are performed, that is, the intake stroke injection by the first injector 15 and the port injection by the third injector 17. .

  Here, the fuel amount injected from the first to third injectors 15, 16, 17 will be described. These first to third injectors 15, 16 operate so as to have an air-fuel ratio corresponding to the operating state of the engine 1. The fuel supplied into the chamber 8 is divided and injected. That is, the total amount of the amount of fuel injected by the first injector 15, the amount of fuel injected by the second injector 16, and the amount of fuel injected by the third injector 17 is the amount of fuel to be supplied into the working chamber 8. equal.

  When comparing the fuel injection amounts by the first and second injectors 15 and 16 in the relatively low load region (low rotation low load region and high rotation low load region), the fuel injection amount of the first injector 15 is The fuel injection amount of the second injector 16 is set to be relatively small. In addition, the fuel injection amount of the third injector 17 executed in the relatively high rotation regions (the high rotation low load region and the high rotation high load region) is the first injector 15 or the first and second injectors 15. , 16 is set so as to compensate for an insufficient amount. Therefore, the fuel injection amount of the third injector 17 is relatively small. The rotary piston engine 1 can be operated up to a higher speed than a reciprocating engine, and its operating range is relatively wide. For this reason, it is advantageous to provide not only the first and second injectors 15 and 16 but also the third injector 17 in order to cope with a wide operating range of the rotary piston engine 1.

  Next, fuel injection control in the rotary piston engine 1 configured as described above will be described with reference to the timing chart of FIG. As shown in FIG. 3, the first injector 15 injects fuel from the vicinity of the top of the rotor housing 3 toward the intake ports 11, 12, 13 in the intake working chamber 8. For this reason, the fuel injection by the first injector 15 may be referred to as intake counter-injection. The fuel injection timing of the first injector 15 is based on the state (compression top dead center: TDC) in which the rotor 2 is in the state shown in FIG. 1 and the volume of the compression / expansion working chamber 8 is minimized (0 °). , The rotational angle (eccentric angle) on the rotational direction side of the eccentric shaft 6 is set within the range of −450 ° to −330 ° ATDC. The rotation angle of the rotor 2 at this time is indicated by a two-dot chain line in FIG. This fuel injection timing is a timing at which the kinetic energy of the intake air in the intake working chamber 8 is large and the intake air flow velocity is also large, and intense intake flow is formed in the intake working chamber 8. For this reason, the fuel can be efficiently diffused by injecting the fuel toward the intake ports 11, 12, and 13 at this timing. Further, since this timing is significantly earlier than TDC, it is possible to ensure a long vaporization atomization time. In this way, a relatively large amount of fuel is efficiently diffused by the intake air opposed injection by the first injector 15, and an air-fuel mixture with good vaporization atomization is formed by securing a long vaporization atomization time. Further, the intake air opposed injection can cool the intake air by the latent heat of vaporization of the fuel and improve the charging efficiency. Thereafter, the working chamber 8 shifts to the compression stroke.

  The second injector 16 injects fuel from the top position of the rotor housing 3 toward the ignition plug 91 in the compression working chamber 8. When the second injector 16 performs fuel injection, both compression injection and preceding injection at a timing before the compression injection are executed, as virtually shown in FIG.

  The timing of compression injection is set within a range of −180 ° to −150 ° ATDC. The rotation angle of the rotor 2 at this time is indicated by a solid line in FIG. 3, which corresponds to the middle stage of the compression stroke. As described above, as the working chamber 8 shifts from the intake stroke to the compression stroke, the flow of the air-fuel mixture (fuel) is relatively delayed with respect to the rotation of the rotor 2. As a result, in the compression / expansion working chamber 8. Causes an inhomogeneity such that the region on the advance side in the rotor rotation direction becomes lean and the region on the delay side in the rotor rotation direction becomes rich. On the other hand, as shown by a thick solid line in FIG. 3, the fuel is injected by the second injector 16 in the direction of the spark plug 91, so that the inside of the compression working chamber 8 is related to the rotation angle of the rotor 2. The fuel can be supplied to a relatively lean area. As a result, the lean region in the compression working chamber 8 and the subsequent compression / expansion working chamber 8 is enriched, and the heterogeneity of the air-fuel mixture with respect to the rotor rotation direction can be eliminated.

  The timing of the preceding injection is set from the latter half of the intake stroke to the beginning of the compression stroke, which corresponds to a range before and after −270 ° ATDC. In the preceding injection, a small amount of fuel is injected at a timing earlier than that of the compression injection, so that the vaporization atomization time is as long as possible to improve the vaporization of the fuel, and the rotor The homogenization of the air-fuel mixture in the compression or expansion working chamber that is flat in the rotation direction is further enhanced.

  Further, when fuel injection is performed by the third injector 17, it is executed at the opening timing of the intake ports 11, 12, 13.

  Then, after the fuel injection by the first, second and / or third injectors 15, 16, 17 is performed, the two T-side and L-side spark plugs 91, 92 are simultaneously connected at a predetermined timing. Alternatively, ignition is performed in the order of the leading side and the trailing side.

  In addition, since the fuel injection timing of the second injector 16, particularly the compression injection, is a slow timing, it is difficult to ensure a sufficient vaporization atomization time. However, since the amount of fuel injected by the second injector 16 is smaller than the amount of fuel injected by the first injector 15, the disadvantage that the vaporization atomization time is short is minimized and the deterioration of the emission property is suppressed. It is possible. Further, the preceding injection may be omitted, and the second injector 16 may perform only one compression injection.

  Here, referring to FIG. 8, a heat generation pattern (see Example, solid line) when intake counter-injection and compression injection are performed in the rotary piston engine 1 having the first and second injectors 15 and 16. ) And a heat generation pattern of a conventional rotary piston engine that performs intake port injection (see comparative example, broken line). The heat generation pattern of the engine of the conventional configuration is a pattern in which two peaks are lined up so that late combustion occurs after the main combustion, which is the first peak, and the heat generation rate (peak height) by the main combustion is also Relatively low. As described above, this is due to the heterogeneity of the air-fuel mixture in the compression / expansion operation chamber. On the other hand, in the engine 1 having the first and second injectors 15 and 16, the air-fuel mixture in the compression / expansion working chamber 8 is homogenized by the divided injection including the intake air facing injection and the compression injection. Therefore, the late combustion is suppressed, and the heat generation rate due to the main combustion is increased accordingly. In addition, in the compression / expansion working chamber 8, the advance side region in the rotor rotation direction is enriched, so that the combustion speed is also increased, and the peak of heat generation due to the main combustion is faster than that of the engine of the conventional configuration. It occurs at the timing. Such improvement of the heat generation pattern (combustion pattern) contributes to improvement of fuel consumption and torque. Therefore, the engine 1 configured as described above can achieve low fuel consumption in a relatively low load operation region.

  Next, fuel injection control of the first to third injectors 15, 16, and 17 by the ECU 100 will be described with reference to the flowchart shown in FIG.

  First, in step S1, the measured values of the above-described various sensors 76, 101 to 106, etc. are read to determine the operating state of the engine 1. In the following step S2, it is determined whether or not a stop condition for the engine 1 is satisfied. If the engine stop condition is satisfied, the process proceeds to step S3 to stop the engine.

  On the other hand, when the stop condition of the engine 1 is not satisfied in step S2, it is determined in step S4 whether the start condition of the engine 1 is satisfied. When the start condition is satisfied, the process proceeds to step S7. When the start condition is not satisfied, in other words, when the engine 1 is operating, the process proceeds to step S5.

  In step S5, it is determined which operating region the operating state of the engine 1 corresponds to in FIG. 10, and in the subsequent step S6, a plurality of maps preset and stored for each operating region of the engine 1 are stored. To read the corresponding map. The ECU 100 also injects an amount of fuel set by the map at a predetermined timing by the corresponding injectors 15, 16, and 17 based on the read map.

  On the other hand, in step S7 for starting the engine 1, it is determined whether or not the engine water temperature is equal to or higher than a predetermined temperature (for example, 60 ° C.), and when the temperature is higher than the predetermined temperature, the process proceeds to step S8. In step S9, the process proceeds to step S9. In step S9, it is determined whether or not the engine 1 is cold (for example, 0 ° C. or lower). If NO, the process proceeds to step S8. If cold, YES, the process proceeds to step S8. The process proceeds to S10.

  In step S8, where the temperature of the engine 1 is relatively high, the starter motor 108 is driven and the intake air counter-injection by the first injector 15 is executed at the start. While the fuel pressure in the accumulator 7 is low and a large amount of fuel cannot be injected from the first injector 15, the warm start is performed by the first injector 15 because the amount of fuel supplied is relatively small. The engine 1 is started by performing the intake counter-injection.

  On the other hand, in step S10 where the temperature of the engine 1 is extremely low, the starter motor 108 is driven and the port injection by the third injector 17 is executed at the time of starting. As described above, since the fuel pressure in the pressure accumulator 7 is low and a large amount of fuel cannot be injected from the first injector 15, the cold start is relatively large in the amount of fuel supplied. Intake-opposed injection by the first injector 15 is difficult. Therefore, port injection is performed by the third injector 17 that allows fuel injection even when the fuel pressure is relatively low. Then, after the fuel pressure has increased, switching to the intake-opposed injection by the first injector 15 is performed.

  As described above, in the engine 1, the charging efficiency improvement effect by the intake air cooling can be obtained by performing the intake air opposing injection by the first injector 15 in the operation region of the relatively high load. This is effective in improving the torque. In addition, the intake counter-injection is more advantageous than the port injection in terms of improving fuel consumption and emission, since the wall surface adhesion of the injected fuel is suppressed. In the relatively high load operation region, injection during the compression stroke is not performed. However, in this operation region, since the set air-fuel ratio is low and the amount of fuel to be supplied is large, relatively lean fuel is generated in the working chamber. Also in the region, the concentration of fuel is relatively high. Therefore, the deterioration of the combustion characteristics is suppressed without performing the compression stroke injection.

  On the other hand, in the operation region where the load is relatively low, intake counter-injection by the first injector 15 and preceding injection and compression injection by the second injector 16 are performed. In the intake counter-injection, fuel is injected at a timing that is significantly earlier than the ignition timing, so that the vaporization atomization time can be secured for a long time. Therefore, the intake air opposed injection by the first injector 15 is advantageous in forming an air-fuel mixture with good vaporization atomization. The compression injection by the second injector 16 can enrich the relatively lean region in the working chamber 8 and eliminate the heterogeneity of the air-fuel mixture. The elimination of the heterogeneity of the air-fuel mixture can improve the combustion characteristics of the rotary piston engine 1, and the improvement of the combustion characteristics can improve the fuel efficiency. Further, the preceding injection by the second injector 16 makes the vaporization atomization time longer to improve the fuel vaporization atomization, and further improves the intake charging efficiency when the preceding injection is performed in the intake stroke. Can be expected.

  FIG. 11 shows a modification related to the arrangement of the first and second injectors 15 and 16. In this engine 1, the first injector 15 is on the compression stroke side with the long axis Y interposed therebetween (on the advance side in the rotational direction of the rotor 2), and the second injector 16 is on the intake stroke side with the long axis Y interposed therebetween (the rotor 2 Are arranged on the delay side of the rotation direction).

  The first injector 15 is directed in the direction of the intake ports 11, 12, 13 to inject fuel directly into the intake working chamber 8, and the second injector 16 is directed in the direction of the spark plug 91 to perform the compression operation. Fuel is directly injected into the chamber 8. Since this arrangement increases the spray flight distance of each of the first injector 15 and the second injector 16, this arrangement is advantageous in suppressing the fuel wall surface adhesion. In FIG. 11, the first and second injectors 15 and 16 are arranged so that their axial centers are parallel to the long axis Y, but as described above, the first and second injectors are arranged. The angle at which the injectors 15 and 16 are disposed is not particularly limited. However, from the viewpoint of simplifying the mounting of the pressure accumulator 7, it is desirable to arrange the first and second injectors 15 and 16 in parallel with each other.

  FIG. 12 shows a modification related to the pressure accumulator 7. In the accumulator 7, the first fuel supply pipe 71 connects the first injectors 15 in the front and rear rotor housings 3 to each other, while the second fuel supply pipe 72 has front and rear rotors. The second injectors 16 in the housing 3 are connected to each other. For this reason, the first and second fuel supply pipes 71 and 72 are disposed so as to extend in parallel to each other in the direction of the rotation axis X. A communication pipe 77 that communicates the first and second fuel supply pipes 71 and 72 with each other is disposed at the center position in the length direction of the first and second fuel supply pipes 71 and 72. The pressure accumulator 7 is configured so as to have an H-shape that is inclined laterally as a whole. Also in this pressure accumulator 7, since the distance between the injectors 15 and 16 using the first and second fuel supply pipes 71 and 72 and the communication pipe 77 as paths becomes equal, the fuel injection amount of each injector 15 and 16 is The error is equal.

  In this pressure accumulator 7, the other end of the first fuel supply pipe 71 is attached to the other end (the left end in FIG. 12) of the connecting pipe connected to the high pressure fuel pump, and the other end of the second fuel supply pipe 72. A fuel pressure sensor 76 is attached to the left end in FIG. The pressure accumulator 7 also has a third opening at the center in the length direction of the first fuel supply pipe 71 in order to perform drilling of the communication pipe 77, and this opening has a blind plug 74. Is attached. Alternatively, the fuel pressure sensor 76 and the blind plug 74 may be interchanged so that the fuel pressure sensor 76 is attached to the position of the blind plug 74 and the blind plug 74 is attached to the position of the fuel pressure sensor 76.

  Here, a two-rotor type engine having two rotors 2 is exemplified, but the number of rotors 2 is not limited to this.

  As described above, this technique is useful in satisfying the requirements for each operation region in a rotary piston engine.

It is a perspective view which shows the outline | summary of a rotary piston engine. It is sectional drawing which simplified the one part which shows the principal part of the same engine. It is a figure which expands and shows the top vicinity in the rotor housing of the same engine. It is explanatory drawing which shows the fuel-injection direction of a 1st and 2nd injector. It is a top view of the engine which shows the composition of a pressure accumulator. It is a block diagram which shows the structure which concerns on control of a rotary piston engine. It is a timing chart regarding operation of a rotary piston engine. It is the figure which compared the heat generation pattern. It is a flowchart which concerns on the fuel injection control of a rotary piston engine. It is a figure which shows an example of the operation area | region regarding fuel-injection control. FIG. 4 is a view corresponding to FIG. 3 showing a modified example related to the arrangement of the first and second injectors. FIG. 6 is a diagram corresponding to FIG. 5 illustrating a modified example of the pressure accumulator.

Explanation of symbols

1 Rotary Piston Engine 11 Intake Port 15 First Injector (First Fuel Injection Valve)
16 Second injector (second fuel injection valve)
17 Third injector (third fuel injection valve)
2 Rotor 3 Rotor housing 31 Rotor housing chamber 3a Trochoid inner peripheral surface 4 Intermediate housing (side housing)
5 Side housing 8 Working chamber 92 Leading side spark plug 91 Trailing side spark plug 100 ECU (control means)
X Output shaft Y Long shaft Z Short shaft

Claims (6)

The rotor is housed in a rotor housing chamber defined by a rotor housing having a substantially elliptical trochoid inner circumferential surface defined by a major axis and a minor axis orthogonal to each other and a side housing arranged so as to sandwich the rotor housing. The three working chambers are partitioned, and the rotor makes a planetary rotational movement around the output shaft, so that the respective strokes of intake, compression, expansion and exhaust are performed in order while moving the working chambers in the circumferential direction. A rotary piston engine configured as follows:
A first fuel injection valve attached to the rotor housing so as to face the working chamber in the intake stroke and directly injecting fuel into the working chamber in the intake stroke;
A second fuel injection valve attached to the rotor housing so as to face the working chamber in the intake or compression stroke and directly injecting fuel into the working chamber in the intake or compression stroke;
Control means for controlling fuel injection by the first and second fuel injection valves such that the air-fuel mixture in the working chamber has an air-fuel ratio set according to the operating state of the rotary piston engine,
At least one of the side housings has an intake port that communicates with the working chamber in the intake stroke so that air can be sucked into the working chamber.
The control means performs fuel injection during the intake stroke by the first fuel injection valve when the operating state of the rotary piston engine is in a predetermined high load operating region, and the operating state of the rotary piston engine is When in the partial load operation region of lower load than the high load operation region, the fuel injection during the intake stroke by the first fuel injection valve and the fuel injection during the compression stroke by the second fuel injection valve are performed. A fuel injection control device for a rotary piston engine. The fuel injection control device for a rotary piston engine according to claim 1,
The rotary piston engine includes at least one spark plug attached to the rotor housing so as to face a working chamber in the compression or expansion stroke,
Each of the first and second fuel injection valves is disposed near a long axis of the rotor housing;
The first fuel injection valve injects fuel in the direction of the intake port when viewed in the output shaft direction;
The second fuel injection valve is a fuel injection control device for a rotary piston engine that injects fuel in the direction of the spark plug when viewed in the output shaft direction. The fuel injection control device for a rotary piston engine according to claim 1 or 2,
When the operation state of the rotary piston engine is in the partial load operation region, the control means is configured to perform fuel injection during the intake stroke by the first fuel injection valve and during the compression stroke by the second fuel injection valve. A fuel injection control device for a rotary piston engine configured to further execute a pre-injection by the second fuel injection valve at a timing between fuel injection. The fuel injection device for a direct injection engine according to claim 3,
The fuel injection timing during the intake stroke by the first fuel injection valve is set so as to overlap with the timing when the intake port is open,
The timing of the preceding injection by the second fuel injection valve is set when the working chamber is in the period from the latter half of the intake stroke to the early stage of the compression stroke, while the fuel injection timing during the compression stroke is the working chamber. A fuel injection control device for a rotary piston engine that is set when is in the middle of the compression stroke. The fuel injection control device for a rotary piston engine according to claim 1 or 2,
A third fuel injection valve controlled by the control means and for injecting fuel into the intake port;
When the operation state of the rotary piston engine is in a predetermined high rotation operation region, the control means is configured to perform fuel injection into the intake port by the third fuel injection valve and intake stroke by the first fuel injection valve. A fuel injection control device for a rotary piston engine that executes at least both fuel injection. The fuel injection control device for a rotary piston engine according to any one of claims 1 to 5,
The rotary piston engine is a fuel injection control device for a rotary piston engine configured such that an air-fuel ratio set in the high-load operation region and an air-fuel ratio set in the partial-load operation region are different from each other.

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