JP4862797B2 - Fuel injection device for rotary piston engine - Google Patents

Description

  The present invention relates to a so-called direct injection type rotary piston engine, and more particularly to a combustion injection technique for improving the combustion stability thereof.

  With regard to this type of technology, for example, there is one in which injected fuel is concentrated in the vicinity of a spark plug during ignition (Patent Document 1). There, the fuel is injected along the flow of the vortex generated so as to swirl in the rotation direction of the rotor from the latter half of the intake stroke to the compression stroke as the rotor rotates.

By doing so, stable stratified combustion can be realized and adhesion of fuel to the inner wall surface of the working chamber can be reduced.
JP-A-6-288249

  On the other hand, from another viewpoint, an attempt is made to diffuse the injected fuel on the flow of intake air to form a uniform air-fuel mixture in the working chamber and burn it.

  However, in this case, since the flow state of the intake air in the working chamber of the rotary piston engine greatly changes depending on the operating state of the engine, the injected fuel is uniformly diffused without adhering the fuel to the inner wall surface of the working chamber. It is difficult to get stable.

  The present invention has been made in view of such a point, and the object of the present invention is to stably suppress the fuel adhesion to the wall surface of the working chamber even when the flow state of the intake air changes greatly, and to reduce the injected fuel. An object of the present invention is to provide a fuel injection device for a rotary piston engine that can be uniformly diffused.

  In order to achieve the above object, according to the present invention, the fuel injection valve is provided with a plurality of injection holes, and in the working chamber in the intake stroke, the spray of fuel from these injection holes causes the intake port and the recess of the rotor to respectively Set to be oriented.

  Specifically, a fuel injection device for a rotary piston engine having a fuel injection valve that directly injects fuel into a working chamber in an intake stroke, the rotor flank surface facing the working chamber in the intake stroke. The fuel injection valve has a plurality of injection holes for injecting fuel, and a part of the plurality of injection holes opens facing the working chamber in the intake stroke. It is configured to inject fuel toward the intake port, and the remaining injection holes are configured to inject fuel toward the recess.

  According to this configuration, first, fuel is injected from a part of the plurality of nozzle holes toward the intake port, but the intake port is opened facing the working chamber, and there is no wall surface there. Therefore, fuel spray does not adhere (hereinafter referred to as non-impact spray). In addition, the atomization, vaporization, and atomization of the fuel are promoted by the collision with the intake air flowing into the working chamber from the opening, and the fuel is effectively diffused by the intake air.

  On the other hand, fuel is injected from the remaining nozzle holes toward the recess formed in the flank surface of the rotor. Although this fuel spray collides with the recess of the rotor (hereinafter referred to as a collision spray), a part of the fuel spray is reflected in the working chamber to prevent the fuel from adhering to the inner wall surface and to effectively disperse the fuel. The

  The non-collision spray is strongly influenced by the intake flow, whereas the collision spray is not greatly influenced by the intake flow. Thus, by dividing the fuel spray in two directions and combining different actions, The influence of the change in the flow state can be alleviated, and it is possible to stably realize the suppression of the fuel adhesion to the inner wall surface and the uniform diffusion of the fuel.

  In this case, the fuel injection timing by the fuel injection valve may be set within a period in which the intake flow velocity in the first half of the intake stroke is equal to or higher than a predetermined value. By doing so, it is possible to efficiently utilize the kinetic energy of the intake air and promote fuel diffusion.

  In particular, based on the results of verification by experiment, it is preferable that the amount of collision spray directed to the recess and the amount of non-impact spray directed to the intake port are set to be substantially the same. Then, stable combustion performance can be obtained. Note that “substantially the same” here means substantially the same meaning, and includes a practically acceptable range in the vicinity of the same spray amount in which the same effect can be obtained.

  Further, the plurality of nozzle holes of the fuel injection valve are close to the intake port on the rotation direction delay side of the rotor in the vicinity of the major axis of the rotor accommodating chamber having a substantially elliptic shape when viewed from the rotation axis direction of the rotor. It is good to arrange it. Then, fuel can be injected relatively quickly into the working chamber in the intake stroke.

  As described above, according to the present invention in which the spray of fuel is directed to the intake port and the recess of the rotor, the inner wall surface of the working chamber is stable even if the flow of the intake air in the working chamber changes greatly. As a result, it is possible to realize a rotary piston engine that can suppress the fuel from adhering to the fuel and can evenly diffuse the injected fuel and exhibit excellent combustion performance.

  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)
1 and 2 show a rotary piston engine 1 (hereinafter simply referred to as engine 1) to which the fuel injection device of the present invention is applied.

  As shown in FIG. 1, the engine 1 is a two-rotor type including two rotors 2 and 2, and the two rotor housings 3 and 3 sandwich these intermediate housings 4 between them. The two side housings 5 and 5 are further integrated from both sides. In FIG. 1, a part of the right side is cut away to show the inside, and the left side housing 3 is also separated to show the inside. In addition, a symbol X in the figure is a rotation axis 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, the inner 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, two inner sides of the rotor accommodating chamber 7 having a substantially elliptical shape like a bowl when viewed from the direction of the rotation axis X are partitioned by the inner side surfaces 4 a and 4 a on both sides of the housing 4. Each of the rotors 2 is accommodated in each of the rotor accommodating chambers 7. The rotor accommodating chambers 7 and 7 are arranged symmetrically with respect to the intermediate housing 4 and have the same configuration except that the position and phase of the rotor 2 are different. The storage chamber 7 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 the outer periphery thereof has three substantially rectangular flank surfaces 2a, 2a, 2a are provided. A recess 2b extending in the major axis direction is formed at the center of each flank surface 2a. The specific shape of the recess 2b will be described later.

  The rotor 2 has a seal portion (not shown) at each top portion, and these seal portions 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 intermediate Three working chambers 8, 8, 8 are defined in the interior of the rotor accommodating chamber 7 by the inner surface 4 a of the housing 4, the inner surface 5 a of the side housing 5, and the flank surface 2 a of the rotor 2.

  A phase gear is provided inside the rotor 2 (not shown). That is, the inner gear (rotor gear) on the inner side of the rotor 2 and the outer gear (fixed gear) on the side housing 5 side mesh with each other, and the rotor 2 is connected to the intermediate shaft 4 and the eccentric shaft 6 that penetrates the side housing 5. And is supported to make 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. While rotating around 6a, it revolves around the rotation axis X in the same direction as rotation (this rotation and revolution are simply referred to as rotation of the rotor in a broad sense). 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 is on the left side of the rotor housing chamber 7 separated from the major axis Y of the rotor housing chamber 7 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, this shows an intake stroke in which an air-fuel mixture is formed by the intake air and the injected fuel, and the working chamber 8 shifts to a compression stroke as the rotor 2 rotates. Then, the air-fuel mixture is compressed inside. Thereafter, as in the working chamber 8 shown on the right side of the figure, the ignition plugs 9 and 9 are ignited at predetermined timings from the end of the compression stroke to the expansion stroke, and the combustion / expansion stroke is performed. Finally, when the exhaust stroke such as the working chamber 8 on the lower left side of the figure is reached, the combustion gas is exhausted from the exhaust port 10 and then returns to the intake stroke to repeat each stroke. Since the fuel injection device of the present invention targets the intake stroke among the above-described strokes, the working chamber 8 (hereinafter referred to as the intake working chamber 8) in the intake stroke will be described in more detail.

(Configuration of fuel injection device)
As described above, the intake working chamber 8 is formed on one end side (the upper side in FIG. 2) of the rotor housing chamber 7 in the major axis Y direction with the rotation of the rotor 2. An injector 15 (fuel injection valve) is arranged to inject fuel directly.

  A plurality of intake ports 11, 12, 13 communicate with the intake working chamber 8. That is, the first intake port 11 is opened near the short axis Z on the outer peripheral side of the rotor housing chamber 7 on the inner side surface 4 a of the intermediate housing 4 facing the intake working chamber 8. Further, as shown in FIG. 1, the inner 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 7 so as to face the first intake port 11. The second intake port 12 and the third intake port 13 are open.

  Thus, 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 region), and further the intake amount When the air intake becomes insufficient, the air is also drawn from the third intake port 13 (high rotation range), and the optimum intake flow rate is maintained even if the intake air amount changes, so that the engine 1 is driven at a low load and a low rotation to a high load and a high rotation. Efficient intake can be achieved over the entire operating range.

  However, when the intake air amount, the intake air direction, and the like change greatly depending on the operating state of the engine 1 as described above, the flow state in the intake working chamber 8 also changes greatly. It is important to improve performance.

  Therefore, first, for the intake working chamber 8 provided with such a plurality of intake ports 11, 12, 13, the fuel injection timing is the intake air flow velocity in the first half of the intake stroke so that the diffusibility of the fuel by the intake air is optimal. Is set within a period in which is equal to or greater than a predetermined value. In other words, the fuel injection timing is set within a period centering on the timing at which the intake working chamber 8 becomes -150 ° (−150 ° ABDC) after the bottom dead center at the eccentric angle.

  Specifically, the flow analysis of the intake air in the intake working chamber 8 as shown in FIG. 3 was performed, and the kinetic energy of the intake air in each period of the intake stroke was examined. The arrow lines in the figure indicate the direction of the intake flow at each point.

  The eccentric angle referred to here is a state in which the top of the rotor 2 is located at the lower end and the volume of the intake working chamber 8 is maximized (bottom dead center: as shown by a virtual line in FIG. 3B). BDC) is the reference (0 ° ABDC), and the rotational angle of the eccentric shaft 6 in the rotational direction with respect to this, and as indicated by the solid line, the state where the rotor 2 has returned about 80 ° in the reverse direction is −150 ° ABDC It corresponds to.

  The graph of FIG. 4 shows the result of comparing the kinetic energy of the intake air in the intake working chamber 8 in the range of −210 ° to −60 ° ABDC in the intake stroke. As shown in this graph, it can be seen that the kinetic energy of the intake air is large with the peak at −150 ° ABDC, the flow velocity of the intake air is large, and a vigorous flow of the intake air flow is formed. Therefore, if fuel is injected within the range of -170 ° to -130 ° ABDC, more preferably from -160 ° to -140 ° ABDC, centering on -150 ° ABDC in the first half of the intake stroke, fuel can be efficiently used. Can be diffused.

  The fuel is injected from one injector 15 provided on the side of the rotor accommodating chamber 7 where the intake working chamber 8 is formed directly into the intake working chamber 8 (for example, FIG. 2). This injector 15 is a multi-hole type having a plurality of injection holes 15a,... For injecting fuel at the tip, and in this embodiment, there are eight injection holes 15a as shown in FIG. Each nozzle hole 15a can adjust the spray amount and the spray direction by setting the nozzle hole diameter (cross-sectional area), its length, and angle, and these nozzle holes can be used for optimal fuel injection. The device is devised for the injection direction and the injection position.

  First, as for the injection direction, as shown in FIG. 6A, a part of the injection holes 15a (here, four injection holes) are provided so that the fuel spray does not collide with the inner wall of the intake working chamber 8. Is set to inject fuel toward the intake ports 11, 12, 13 (sprays injected from these injection holes 15 a,... Are collectively referred to as non-impact spray S 1). On the other hand, as shown in FIG. 5B, the remaining injection holes 15a (here, four injection holes) are recessed in the flank surface 2a of the rotating rotor 2 so that the fuel spray collides with the rotor 2. Are set so as to inject the fuel in the direction (the sprays injected from these injection holes 15a,... Are collectively referred to as a collision spray S2). FIG. 5 shows a state at −150 ° ABDC.

  Specifically, in FIG. 6A, in the non-impact spray S <b> 1, the spray center is in a direction inclined approximately 40 ° toward the intake ports 11, 12, and 13 with respect to the long axis Y of the rotor accommodating chamber 7. Each nozzle hole 15a,... Is oriented so as to match. This approximately 40 ° is based on the inclination angle between the straight line connecting the tops of the rotors 2 located at both ends of the intake working chamber 8 in this state (−150 ° ABDC) and the long axis Y of the rotor accommodating chamber 7.

  On the other hand, in the collision spray S2, as shown in FIG. 6 (b), 0 ° to 30 ° toward the intake ports 11, 12, 13 with respect to the long axis Y of the rotor housing chamber 7 in accordance with the shape of the recess 2b. Each nozzle hole 15a is oriented so that the spray center coincides with the inclined direction.

  Here, the shape of the recess 2b will be specifically described. As shown in FIG. 1, the recess 2b is a substantially central portion of each flank surface 2a of the rotor 2 and has a curved surface that is gently inclined inward from the flank surface 2a. It has a long and narrow shape extending in the long axis direction of the flank surface 2a. Therefore, when the fuel injected toward the surface of the recess 2b collides with the surface of the recess 2b as shown by the arrow line in FIG. 7, it is reflected toward the center in the intake working chamber 8, and the intake working chamber 8 8 hardly adheres to the inner side surfaces 4a and 5a.

  Next, as for the injection position, the eight injection holes 15a,... And is configured to face the intake working chamber 8 from there.

  Specifically, in FIG. 6A, a tangent line L1 inclined by 40 ° contacting the trochoid inner peripheral surface 3a defining the rotor accommodating chamber 7 facing the intake working chamber 8 and the rotor facing the intake working chamber 8 are used. Each of the nozzle holes 15a,... Is provided at a site on the long axis Y side where the intermediate line L3 between the tangent line L2 which is in contact with the surface of the second recess 2b and which is inclined by 40 ° intersects the trochoid inner peripheral surface 3a. . By doing so, fuel can be injected into the intake working chamber 8 relatively early, and in combination with the fuel injection direction of the non-collision spray S1 of approximately 40 °, the fuel is injected with the non-collision spray S1. It is possible to increase the spray distance that the fuel flies in the intake working chamber 8 without colliding.

  Furthermore, it is preferable that the spray amount of the non-collision spray S1 and the spray amount of the collision spray S2 thus distributed are set substantially the same. The ratio of the spray amount has been found by various experiments. Hereinafter, the contents of Experiments 1 to 3 will be described.

  First, in conducting the experiment, as shown in FIG. 8, spray conditions in which the ratios of the spray amounts of the non-collision spray S1 and the collision spray S2 are different are set. For example, in the figure, the condition A is a comparative example in which the total spray amount is set to a non-impact spray S1 (S1: 100, S2: 0), and the conditions B to D are those in which the spray amount is distributed as a test example. (For example, B is S1: 75, S2: 25). Moreover, the schematic of the spray state is shown under each condition.

(Experiment 1)
The fuel efficiency improvement rate (%) at a predetermined injection pressure (12 MPa) was compared under each of the spray conditions of conditions A to D. The result is shown in the graph of FIG. The vertical axis in the figure represents the fuel efficiency improvement rate (%), and the horizontal axis represents the ratio of the collision spray S2 when the total spray amount is 100. The fuel efficiency improvement rate (%) is for a known port injection type rotary piston engine, and is a predetermined condition of a general low speed and low load (engine speed: 1500 rpm, BMEP: 294 kPa, etc.). Compared below.

  As shown in the figure, an increase in fuel efficiency improvement rate of about 2% was observed under any condition including the comparative example, but the fuel efficiency improvement ratio under condition C (S1: 50, S2: 50) was the highest. The fuel efficiency improvement rate tended to decrease as the difference in spray amount increased. Although not shown in the figure, when the fuel injection pressure is changed, the difference in the fuel efficiency improvement rate tends to increase as the spray amount difference increases. The ratio of the spray amount of the spray S2 is preferably about 30 to 60 with the total spray amount being 100, and it has been confirmed that it is more preferable to set both to be the same.

(Experiment 2)
Next, the effect of changes in the flow state of intake air on the fuel improvement rate was investigated. The fact that the flow state of the intake air changes greatly in conjunction with the operating state of the engine 1 has been described above, but it is necessary to realize stable and efficient combustion against the change.

  In the experiment, in the case of intake from only the first intake port 11, the case of intake from the first and second intake ports 11, 12, and the case of intake from the first and second intake ports 11, 12, The fuel efficiency improvement rate (%) was compared in three intake states when the intake amount was reduced to half. Other conditions are the same as in the previous test.

  The result is shown in the graph of FIG. There, the results of the condition A (S1: 100: S2: 0) as a comparative example and the condition D (S1: 25, S2: 75) as a test example are shown. In the figure, the symbol P indicates the case of intake from the first intake port 11, the symbol P + S indicates the intake from the first and second intake ports 11, 12, and the symbol P + S / 2 indicates the first and second intake ports. A case is shown in which the intake air amount is reduced by half from the intake ports 11 and 12.

  As is apparent from this graph, under condition D, a fuel efficiency improvement rate of nearly 2% was recognized under any conditions with different intake states, and the variation was small and stable. In condition A, a condition showing a fuel efficiency improvement rate exceeding 2% was recognized, but on the other hand, a condition of less than 0.5% was recognized, and a tendency for the fuel efficiency improvement ratio to vary greatly was recognized. This is mainly because the total spray amount is injected toward the intake ports 11, 12, and 13 in the condition A, so that it is strongly influenced by the intake state, whereas the spray amount is distributed in the condition D. The effect seems to have been suppressed.

  Therefore, it is confirmed that an excellent fuel efficiency improvement rate can be stably exhibited even when the intake state changes by distributing not only the non-collision spray S1 but also a part thereof to the collision spray S2. It was.

(Experiment 3)
When the fuel adheres to the inner wall surface of the intake working chamber 8, a combustion defect is caused and a small amount of smoke is generated. Suppressing the generation of smoke is an important issue in terms of engine combustion performance as well as improving fuel efficiency. Therefore, in order to examine the influence of the ratio of the spray amount on the generation of smoke, fuel injection is performed at each timing of the intake stroke (−210 ° to −60 ° ABDC) described above, and the amount of smoke generated at that time (FSN) were compared. The other conditions, such as the engine speed, are the same as in Experiment 1 above.

  The result is shown in the graph of FIG. There, the results of the condition B (S1: 75, S2: 25) and the condition D (S1: 25, S2: 75) are shown. As shown in the figure, in condition B, no smoke was observed in a wide range of the intake stroke, and a slight occurrence was observed after -100 ° ABDC. On the other hand, in condition D, no smoke was observed at the initial stage of the intake stroke, but a tendency to smoke was observed after -140 ° ABDC. This is because the collision spray S2 uses the reflection of the recess 2b of the rotating rotor 2 and is easily affected by the rotation angle of the rotor 2. When the ratio of the spray amount increases, the adhesion amount increases and the vaporization occurs. It seems that the atomization was insufficient and the combustion failure increased. Therefore, it is considered that excessively increasing the ratio of the collision spray S2 may cause the generation of smoke. From the viewpoint of suppressing the generation of smoke, the ratio of the spray amount of the collision spray S2 does not exceed 75. It was confirmed that the generation of smoke can be effectively suppressed if it is less than that.

  As described above, when the fuel supply device of the present invention is applied to a rotary piston engine, the adhesion of fuel can be effectively suppressed and the injected fuel can be evenly diffused to realize stable and efficient combustion. Will be able to.

  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 embodiment, the two-rotor type engine 1 is shown, but the present invention is not limited to this. The number of nozzle holes 15a may be two or more. The number of intake ports is not limited to three and may be two. The plurality of injection holes 15 a of the injector 15 can be arranged on the long axis Y line of the rotor accommodating chamber 7 or in the vicinity thereof away from the intake ports 11, 12, 13.

1 is a perspective view showing an outline of a rotary piston engine according to an embodiment of the present invention. It is sectional drawing which simplified one part which shows the principal part of the same engine. FIG. 5 is a diagram for explaining a flow analysis in the intake working chamber 8. (A) is a perspective view, (b) is the side view. 6 is a graph showing the result of flow analysis in the intake working chamber 8; It is a schematic diagram of the nozzle hole of an injector. It is a figure for demonstrating the specific structure of a fuel-injection apparatus. (A) has shown the structure of non-impact spray, (b) has shown the structure of collision spray. It is a figure for demonstrating the reflection of the fuel in a recess. It is the figure which put together the spraying conditions in experiment. 6 is a graph showing the results of Experiment 1. 10 is a graph showing the results of Experiment 2. 10 is a graph showing the results of Experiment 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rotary piston engine 2 Rotor 2a Frank surface 2b Recess 3 Rotor housing 4 Intermediate housing 5 Side housing 7 Rotor accommodating chamber 8 Working chamber (intake working chamber)
11 First intake port 12 Second intake port 13 Third intake port 15 Injector (fuel injection valve)
15a nozzle hole
X Rotating axis Y Long axis Z Short axis

Claims (4)

A fuel injection device for a rotary piston engine having a fuel injection valve for directly injecting fuel into a working chamber in an intake stroke,
A recess is provided in the flank of the rotor facing the working chamber in the intake stroke,
The fuel injection valve includes a plurality of injection holes for injecting fuel,
A portion of the plurality of nozzle holes is provided so as to inject fuel toward an intake port that opens facing the working chamber in the first half of the intake stroke;
A fuel injection device for a rotary piston engine, wherein the remaining injection holes are provided so as to inject fuel toward the recess. The fuel injection device for a rotary piston engine according to claim 1,
The fuel for the rotary piston engine is characterized in that the fuel injection timing by the fuel injection valve is set within a period of -170 ° to -130 ° ABDC centering on -150 ° ABDC in the first half of the intake stroke. Injection device. The fuel injection device for a rotary piston engine according to claim 1 or 2,
The fuel injection of the rotary piston engine, wherein the spray amounts of the collision spray that is fuel spray directed to the recess and the non-impact spray that is fuel spray directed to the intake port are set to be substantially the same. apparatus. In the fuel-injection apparatus of the rotary piston engine as described in any one of Claims 1-3,
The rotor accommodating chamber has a substantially elliptical shape when viewed from the rotational axis direction of the rotor,
The fuel injection device for a rotary piston engine, wherein the plurality of injection holes of the fuel injection valve are disposed near the intake port on the rotation direction delay side of the rotor in the vicinity of the long axis of the rotor accommodating chamber. .

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