JP3302736B2 - Engine fuel control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel control system for an engine, and more particularly to a fuel control system for a rotary engine having a high-pressure fuel injection valve for directly injecting fuel into a cylinder.

[0002]

2. Description of the Related Art Early rotary engines were of a premixed combustion type in which a mixture was sucked through an intake port. However, in order to satisfy the recent demands such as reduction of fuel consumption, purification of exhaust gas, and improvement of rotational performance, stratification that controls ignition and combustion propagation by appropriately distributing air-fuel mixtures having different air-fuel efficiencies in the working chamber. Has been attempted.

As one of them, in addition to a premixed combustion system, a DISC (Direct Inje
The system has a high-pressure fuel pump and high-pressure injection valve for ction stratified charge (direct injection stratified intake), and uses a premixed combustion + DISC system in the area where high output is required, and a system using only DISC in the low rotation light load area. Are known. For example, JP-A-1-18732 discloses a rotary engine using both premixing and DISC.

As for stratified combustion by in-cylinder high-pressure injection, a system without a throttle condition (boost 0 mmHg) is generally known as in a diesel engine, but RE-DISC is a premixed system. Therefore, all the areas of only the DISC are under the throttle condition. For that purpose, if the stratification of the diesel engine is assumed to be a strong stratification, in the throttle-DISC,
It is necessary to raise the air utilization rate by creating a weakly stratified state with many vaporized states.

[0005]

However, as shown in FIG. 4, the high-pressure injection nozzle is placed at 40 ^° to 2 ^° after the compression top.
At 40 ^o on the trochoid through which the apex seal passes, when the distance between the spark plug and the high-pressure injection nozzle is close, the boost is close to the atmosphere (-100 mm) (even if the injection direction is optimized).
(Hg or lower) state, ignition and stable combustion occur in a certain region, but the boost is -200, -300, -400 mmHg.
As fuel consumption increases, fuel economy deteriorates significantly, and finally the vehicle cannot be driven. The reason that the fuel efficiency and driving performance deteriorate significantly under the throttle condition is that the stratification is strong because the injection distance is short and the vaporization time is short where the intake air volume is small. -There will be problems with DISC.

On the other hand, as shown in FIG. 2 of JP-A-1-187321, when the high-pressure injection nozzle is provided on a trochoid through which an apex seal passes on the intake side more than 30 ^° before the compression top, the former phenomenon can be solved. Conversely, stratification cannot be achieved and the state becomes close to a premixed combustion state. This is the injection distance
This is because it is easy to vaporize due to the long time, and furthermore, because the fuel mixes air with the air flow, stratification does not occur.
The effect as C disappears.

Further, in the fuel injection timing, during a cold start, the vaporization state is poor, so that it is desirable to shorten the vaporization time by the early injection. However, it is difficult to start the fuel injection when the injection valve is located on the compression top side or depending on the direction.

The present invention, the removed conventional drawbacks, having an engine structure and a fuel injection timing which is improved to solve conflicting requests simultaneously that sufficient vaporization and stratification
An engine fuel control device is provided.

[0009]

In order to solve this problem, an engine fuel control apparatus according to the present invention is directed to a rotary engine having a high-pressure fuel injection valve for directly injecting fuel into a cylinder. Approximately 3 compression valves
0 ° before, almost 40 ° after the compression top, after the compression top
With apex seals provided on trochoid passing toward the spark plug located in the fuel injection direction from the high-pressure fuel injection valve is set to be substantially parallel to the trochoid major axis, the fuel of the high-pressure fuel injection valves Injection hole
Into an oval shape with the major axis in the crankshaft direction for cold start
The timing of fuel injection at the time
It is characterized in that it shall be the fastest time to fit in the recess
You .

[0010]

【Example】

<Configuration Example of Rotary Engine of the Present Embodiment> FIG. 1 is a schematic configuration diagram of a rotary engine that uses both DISC and premixed combustion of the present embodiment. Reference numeral 10 denotes a rotary engine body, which has a trochoid inner wall 11, and a rotor 18 which presses against the trochoid inner wall 11 is rotated by three apex seals 11a to 11c. An output shaft 19 is provided at the center of the rotor 18.
Rotates three times, whereby ignition combustion is performed once per rotation of the output shaft 19. Reference numeral 12 denotes a high-pressure fuel injection nozzle, which is arranged at a position close to the spark plugs 13 and 14 in this embodiment, as shown in FIG. Details of this position will be described below with reference to FIGS.

Reference numeral 15 denotes an intake system having a throttle 16, and a nozzle 17 for premixing is provided. Reference numeral 20 denotes a microcomputer (ECU) that controls the fuel of the engine of the present embodiment, and has a CPU, a ROM, and a RAM as basic elements. In FIG. 1, thin elements and signals directly related to the present embodiment are omitted. The high pressure fuel injection nozzle 12 controls the angle sensor 2 under the control of the ECU 20.
The fuel is injected at a predetermined timing from 1.

FIG. 2 is a diagram showing a DISC in the engine of this embodiment.
FIG. 7 is a diagram illustrating control of premixing and premixing. Note that the DISC region and the premixed region are not clearly separated as shown in FIG. 2, and the DISC and the premixed region are used together in a considerably wide range of the boundary region. FIG. 3 illustrates two examples of preferred nozzle positions of the present embodiment. FIG. 3 (a)
Indicates a position before the top (approximately 30 ° before the output shaft = 10 ° from the rotor), and FIG. 3B illustrates a position after the top (substantially 30 ° after the output shaft). This position is, as described above with reference to FIG.
This is a position where the fuel efficiency is low and the fluctuation due to boost is not increased. Further, the nozzle is installed so as to inject fuel in a direction substantially square with the major axis of the trochoid. This is an arrangement in which stratification is realized and fuel is sufficiently vaporized. The nozzle position is approximately 30 ° before the top to approximately 40 ° after the top
Is preferable.

FIGS. 5 and 6 are diagrams for explaining the injection timing from the nozzle at the above-mentioned position. FIG. 5 is a diagram of a rig test result showing a relationship between a spray reaching distance and time, and FIG. 6 is a diagram showing a preferable fuel injection. As shown in FIG. 6, which is a diagram showing an example of the state performed, the injection timing is preferably such that the tip of the spray just reaches the trailing edge of the rotary recess, and is not generally determined by the angle of the output shaft. FIG.
Assuming that the nozzle is substantially at the top position and the plug and the nozzle are separated from each other by about 100 mm from the conditions shown in FIG. 4, the preferred timing is about 90 ° before the top during the cold start. Note that the state of spraying the fuel is different at the time of a cold start, at the time of operation, and the like, and it is more preferable to consider an optimal timing.

FIG. 8 is a diagram showing the tip shape and spray state of the nozzle tip designed in consideration of the nozzle position of the present embodiment. FIG. 7 is an improved tip shape and spray state of the nozzle tip of the present embodiment. FIG. In particular, at the nozzle position of this embodiment as shown in FIG. 3B, since the tip of the nozzle and the trochoid wall are not separated, it is necessary to prevent the spread of the spray by reducing the diameter of the nozzle as shown in FIG. is there. However, when the nozzle diameter is reduced, the spread in the Y direction is also reduced as shown in FIG. 8, and the spray does not spread in the rotary recess, so that vaporization is hindered.

Therefore, as shown in FIG. 7, when the tip of the nozzle is formed into an elliptical shape whose major axis is in the X direction (crankshaft direction), it is possible to suppress the spread of the spray in the X direction and obtain a sufficient shape in the Y direction. The spread can be secured. The shape of the tip of the nozzle tip makes the features of the nozzle position and spray direction of the present invention shown in FIG. 3 more effective.

<Points of Rotary Engine of this Embodiment> Point 1 A high-pressure injection valve is provided on a trochoid through which an apex seal passes from 30 ^° before the compression top to 60 ^° after the top. The direction of the injection valve is almost parallel to the long axis of the trochoid (downward in the case of a mass-produced engine). The hole system of the injection hole provided on the trochoid sliding surface is compressed pressure and combustion gas blow-through (leakage)
Is desirably φ2 mm or less (which does not affect the performance). With the above configuration,
The driving line in the high boost region, which was a problem with the throttle-DISC, and a significant improvement in fuel efficiency can be obtained.

Point 2 In the injection timing obtained from the actual machine data by the configuration of point 1, the fuel efficiency is highest at 60 ^° before the compression top. The ignition timing at this time is 30 ^° before the top. The distance from the injection valve of the actual machine to the L plug is 100 mm, and the injection time is about 3 ms as shown in the graph. From this, the injection timing at the mounting position of the injection valve described at the point 1 using the mass-produced trochoid is such that the distance between the injection valve and the plug is approximately 90 to 120 mm.
Then, the flying time of the injection at that time is about 2.5 to 4.
It is 5 ms, and if it is injected at about 50 to 70 ^° before the compression top, an optimum air-fuel mixture (stratification) can be obtained, which is effective for fuel consumption.

Point 3 When the injection valve is mounted at a position 100 mm away from the spark plug (described in the first point), the injection timing at the cold start is the fastest timing at which the injection fits in the rotary recess, before the compression top. By injecting at 90 ^° , the vaporization time until ignition can be obtained, and the startability is improved by optimal stratification.

Point 4 Since the injection hole of the conventional injection valve is circular, the injection has a generally long conical shape. In order to further increase the air utilization rate while maintaining the stratification, the injection hole is made into an elongated hole (an oval shape) to make the injection flat. The flattened injection is expanded in the width direction of the housing as far as it enters the recess, and the short axis direction is prevented from hitting the trochoid wall surface. An improvement is obtained.

[0020]

According to the present invention , fuel control of an engine having an improved engine structure and fuel injection timing simultaneously solving the conflicting requirements of sufficient vaporization and stratification.
Equipment can be provided. That is, stratification is possible in the entire operation range. Further, both vaporization and stratification can be achieved. Moreover, stratification can be performed in the recess without spraying the trochoid wall surface, and there is an effect that startability and fuel efficiency are improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a rotary engine using both DISC and premix according to the present embodiment.

FIG. 2 is a diagram illustrating control of DISC and premixing in the engine of the embodiment.

FIG. 3 is a diagram illustrating two examples of nozzle positions in the engine of the embodiment.

FIG. 4 is a diagram illustrating the influence of the distance between a plug and a nozzle in the engine of the embodiment.

FIG. 5 is a diagram illustrating a relationship between a spray reaching distance and a delay time in the engine of the present embodiment.

FIG. 6 is a diagram showing one preferable injection timing (at the time of a cold start) in the engine of the embodiment.

FIG. 7 is a diagram showing a tip shape and a spray state of an improved nozzle tip in the engine of the present embodiment.

FIG. 8 is a diagram illustrating a tip shape and a spray state of a nozzle tip according to a nozzle position in the engine of the present embodiment.

[Explanation of symbols]

10: Rotary engine body, 11: Trochoid inner wall, 11a to 11c: Apex seals 11a to 11
c, 12 high-pressure fuel injection nozzle, 13, 14 spark plug, 15 intake system, 16 throttle, 17 premix nozzle, 18 rotor, 19 output shaft, 20 micro computer (ECU), 21 Angle sensor

──────────────────────────────────────────────────続 き Continuation of the front page (56) References Japanese Utility Model Showa 51-33603 (JP, U) Japanese Utility Model Showa 49-19109 (JP, U) (58) Fields surveyed (Int. Cl. ⁷ , DB name) F02B 53/10 F02M 61/18

Claims (1)

(57) [Claims] 1. A rotary engine having a high pressure fuel injection valve for direct fuel injection into the cylinder, the high-pressure fuel injection valve, approximately 30 ° before after approximately 40 ° of the compression top compression top, after compression top Ignition plug
And a fuel injection direction from the high-pressure fuel injection valve is set to be substantially parallel to the long axis of the trochoid, and a fuel injection hole of the high-pressure fuel injection valve is provided. The crank
The axial and oval shape with the major axis, the timing of fuel injection during a cold start, fuel spray
There fuel engine control apparatus wherein the fastest time and be Rukoto falling within Rotarisesu.