JP3329239B2 - Fuel injection valve - 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 injection valve for a direct injection internal combustion engine having a plurality of slit-shaped injection holes.

[0002]

2. Description of the Related Art In a spark ignition type direct injection engine, when the load is low, fuel is injected in the latter half of the compression stroke to improve stratified combustion to improve fuel efficiency, and when the load is high, fuel is injected into the intake stroke to achieve homogeneous combustion. Is generally performed to increase the output.
In this case, the ideal injection mode is a mode in which fuel is concentrated near the spark plug in the former (stratified combustion), and a mode in which the fuel is uniformly dispersed in the entire combustion chamber in the latter (homogeneous combustion). To satisfy both, JP-A-3-78562 describes that
A fuel injection valve having a plurality of slit-shaped injection holes and forming a flat wide-angle spray has been proposed. The direction and shape of the spray are substantially constant irrespective of the change in the fuel injection amount due to the change in the engine load.

[0003]

However, since the most desirable values of the fuel injection direction and the spray angle change depending on the injection amount and the strength of the airflow, the ideal fuel supply in the entire operation range of the engine is achieved. There is a problem that the distribution is not obtained. Therefore,
It is desired that the injection direction and the injection shape can be changed according to the engine operating state by some method so that the fuel distribution state is optimized. An object of the present invention is to provide a fuel injection valve whose injection direction and spray shape change according to the engine operating state (accordingly, the fuel injection amount). Another object of the present invention is to provide an engine operating condition (hence,
The purpose of the present invention is to make it possible to form an ideal injection direction and spray shape in all engine operating states by using a fuel injection valve whose injection direction and spray shape change according to the fuel injection amount).

[0004]

The present invention to achieve the above object is as follows. (1) A fuel injection valve having a plurality of slit-shaped injection holes , wherein the plurality of slit-shaped injection holes are formed in a fuel injection valve shaft center.
Formed only on one side, the plurality of slit-shaped injection holes
The plurality of slots are formed to be inclined with respect to the axis of the fuel injection valve.
Angle of the slit-shaped injection hole from the axis of the fuel injection valve
The angle between the injection holes is set in the range of 10 to 50 ° so that the spray shape changes due to a change in fuel pressure. When the engine is under a high load, the fuel injection amount is large and the fuel pressure is increased. Lowering the spray shape to a wide-dispersion type in which multiple sprays extend in the injection direction and are separated from each other.When the engine is at medium load, the fuel injection amount is medium and the fuel pressure is increased to increase the spray shape. The sprays are concentrated under a negative pressure to form a single united spray at the center.When the engine is under low load, the fuel injection amount is small and the fuel pressure is increased to increase the spray shape. A fuel injection valve which is a mixed centralized type in which a dispersed type and a centralized type of the single united spray are mixed. (2) When there are two slit-shaped injection holes, one injection hole is inclined at an angle α from the fuel injection valve axis, and the other injection hole is inclined at an angle α + θ from the fuel injection valve axis. In addition, the forming directions of the spray are (α, α + θ) and (α + θ).
(2).

[0005] In the fuel injection valve of the above (1), since the angle formed by the slit-shaped injection holes is in the range of 10 to 50 °, the spray forming direction and the spray shape are variable. In this case, 10 °
If smaller, the sprays sprayed from the plurality of injection holes are always united into one, and cannot form a plurality of separate sprays.
If the angle is larger than 0 °, the sprays sprayed from the multiple orifices are always separated and cannot form a single combined spray, and the shape of the spray changes between the separated spray and the combined spray. However, in the present invention, the angle formed by the injection hole is 10 to 50 °.
, The fuel injection direction and the spray shape are variable. Also, by changing the fuel pressure, the direction of spray formation and the shape of the spray are changed. The direction of spray formation and the shape of spray are changed depending on the fuel injection amount and fuel pressure.However, the injection amount is determined according to the load, and the determined value cannot be changed. by changing the formation of the spray direction, Ru alter the spray pattern. In addition, due to changes in fuel pressure, the spray shape is a wide dispersion type in which multiple sprays extend in the injection direction and are separated from each other, and multiple sprays are brought together under negative pressure to unite to form a single united spray in the center Centralized type, and a centralized type in which the wide dispersion type and the combined type are mixed. When the injection amount is small, the fuel pressure is high.
In other cases, a mixed centralized type is formed. When the injection amount is medium to large, when the fuel pressure is low, a concentrated type in which a wide dispersion type and a united type are mixed is formed, and when the fuel pressure is high, a concentrated type having a single united spray is formed. Also, the fuel pressure is high at low engine load,
Higher in engine load, low in the engine high load, since it is controlled, when the injection injection amount is and the fuel pressure is high small spray centralized the combined type with wide distributed mixed is formed, the medium is injection quantity When the fuel pressure is high and the fuel pressure is low, a wide dispersion type spray is formed, and when the injection amount is medium to large and the fuel pressure is high, a concentrated spray having a single united spray is formed. This is an optimal spray shape according to the engine load. Fuel injection of (2) above
In the firing valve, the direction of spray formation is
(Α, α + θ) and (α + θ / 2). injection
When the amount is small, spraying is performed in two directions, α and α + θ, when the fuel pressure is low.
When the fuel pressure is high, the spray is
formed in two directions of θ and one direction of α + θ / 2 in the later stage of injection.
It is. When the injection amount is medium to large, the spray is α when the fuel pressure is low.
And α + θ are formed in two directions. When the fuel pressure is high, the spray
It is formed in one direction of θ / 2.

[0006]

1 and 2 show a front end portion of a fuel injection valve 1 according to an embodiment of the present invention and a portion in the vicinity thereof. This fuel injection valve 1 is used for a direct injection type spark ignition type internal combustion engine. The fuel injection valve 1 includes a valve body 2 having a valve seat 6.
A valve body 5 that is detachably seated on the valve seat 6, a sack portion 7 formed on the tip side (downstream side) of the valve seat 6, a fuel pool 3 formed in the sack portion 7, and a sack portion 7. It has a plurality of (in the figure, two cases are shown) slit-shaped injection holes 4 a and 4 b formed in the wall, and a fuel passage 8. The tip of the sack 7 has a hemispherical shape.

[0007] A plurality of slit-shaped (flat) injection holes 4a, 4
b is formed only on one side of the fuel injection valve shaft core 9,
Moreover, it is formed so as to be inclined with respect to the fuel injection valve axis 9. The angles of the plurality of injection holes 4a, 4b from the fuel injection valve shaft center 9 are different from each other. When the number of the injection holes 4a and 4b is two, one injection hole 4a is inclined at an angle α (α> 0) from the fuel injection valve axis 9 and the other injection hole 4b is further inclined at an angle θ from the injection hole 4a. (Θ> 0). Therefore, the angle of the injection hole 4b from the fuel injection valve axis 9 is α + θ.

The angle formed by the plurality of injection holes 4a and 4b (the injection holes 4a and 4b)
are set to an angle in the range of 10 to 50 °. The reasons for limiting the numerical values of 10 ° and 50 ° are as follows. When the angle is smaller than 10 °, the sprays sprayed from the plurality of injection holes 4a and 4b cannot always be combined with each other to form a separate spray, and when the angle is larger than 50 °, the sprays from the plurality of injection holes 4a and 4b This is because the applied spray cannot always be separated to form a combined spray. That is, 10
Only when the angle is set in the range of 50 °, by changing the injection amount and the fuel pressure, the spray is separated spray,
The spray may be changed to a combined spray or a mixed spray of separation and coalescence, and an optimal spray form according to the load of the internal combustion engine may be obtained.

The reason why the injection holes 4a and 4b are formed in a slit shape is to make the spray from each of the injection holes 4a and 4b into a flat spray. Further, as shown in FIG. 2, each of the injection holes 4a, 4b
Is δ (δ> 0) from the center 10 of the hemisphere of the sack 7
Only downstream, so that the spray is fan-shaped.

The angle θ between the injection holes 4a and 4b is 10 to 50.
When the condition of being in the range of ° is satisfied, the form of the spray (the forming direction of the spray, the shape of the spray) changes as shown in FIG. 3 depending on the injection amount and the fuel pressure (fuel pressure). This is for the following reason. For a while after the start of the injection, the jets fly out in the directions of α and α + θ, which are the directions of the injection holes 4a and 4b. If the spray speed is low, it will fly in each direction as it is, so the spray will spread over a wide area,
A nearly homogeneous fuel distribution is obtained over a wide range of the combustion chamber. When the speed of the spray is high, the spray attracts the surrounding air, and the air in the space between the two sprays is sucked out and the atmospheric pressure is lower than that of the surroundings. Spray coalesces, coalescing spray α + θ /
It will fly in the direction of the angle of 2.

The following two points are necessary for the above-mentioned coalescing spray phenomenon to occur. Spray flying at high speed to attract air. Spraying for a time equal to or longer than the time required until the pressure in the space between the two sprays decreases. The columns a, b, c, and d in FIG. 3 show the spray forms when the injection amount and the fuel pressure are changed.

[0012] The injection amount is medium to large and the fuel pressure is high (for example, 1
In the case of 0 MPa or higher and high speed) (column d in FIG. 3), the above two requirements are satisfied, and the combined spray is α + θ / 2.
Are formed in the direction of the angle. When the injection amount is medium to large and the fuel pressure is low (for example, lower than 10 MPa, the speed is low) (column C in FIG. 3), since the injection speed is low, the requirement is not satisfied, and in the α, α + θ directions, Two sprays are formed. When the injection amount is small (the injection time is short because the injection amount is controlled by the length of the injection time, the injection time is short) and the fuel pressure is high (for example, 10 MPa or more, the speed is high) (column B in FIG. 3). Since the time is short, the requirement becomes insufficient, and two sprays formed in the α and α + θ directions, which are the initial spray directions, and a combined spray formed in the α + θ / 2 direction by being attracted to each other are mixed. are doing. When the injection amount is small and the fuel pressure is low (for example, lower than 10 MPa, the speed is low) (column a in FIG. 3), the spray is almost similar in shape to the one in FIG.

An apparatus in which the fuel injection valve 1 according to the embodiment of the present invention is applied to a spark ignition type direct injection type internal combustion engine will be described.
In this device, as shown in Table 1, the required spray form differs depending on the engine operating state. To achieve this, the fuel pressure is changed according to the engine operating state to change the spray form. ing. Since the injection amount has a proportional relationship with the load, it cannot be an operation parameter of the spray forming condition. Therefore, the spray form is changed only by the fuel pressure.

[0014]

[Table 1]

FIG. 4 shows an in-cylinder direct injection spark ignition type internal combustion engine equipped with the fuel injection valve 1 of the embodiment of the present invention to satisfy the requirements of Table 1. In FIG. 1, reference numeral 11 denotes a piston having a cavity (corresponding to the cavity in Table 1) 11a, reference numeral 12 denotes a spark plug, and reference numeral 1 denotes a fuel injection valve.
Fuel from the fuel tank 13 is pressurized by the pump 14 and supplied to the fuel injection valve 1 through the reservoir 15. The pressure of the fuel in the reservoir 15 can be adjusted to a higher or lower level by a pressure regulator 16.

An ECU (electronic control unit) 17 receives a current engine operating state load signal 19 from an accelerator 18, a rotation speed sensor, etc., and receives a required spray form (spray forming direction, spray forming direction, spraying) required by the current engine load. Shape etc.)
Is determined from Table 1 or the like stored in advance, and the spray formation conditions (fuel injection amount value, fuel pressure value) corresponding to the required spray form
Is obtained from Table 1, and a fuel injection control signal 21 and a fuel pressure control signal 20 corresponding to the spray formation conditions are issued to the fuel injection valve 1 and the pressure regulator 16, respectively.

Thus, the required spray form is realized, and an optimum spray form for each engine operating state is generated.
The operation and effect of the embodiment of the present invention are achieved. In this case, the injection amount is determined according to the load, and the required spray form is controlled by increasing or decreasing the fuel pressure. Means to raise and lower the fuel pressure,
A known method may be used.

[0018]

According to the fuel injection valve of the first aspect, since the angle formed by the slit-shaped injection holes is in the range of 10 to 50 °, the spray forming direction and the spray shape can be changed. Also, by changing the fuel pressure, the direction of spray formation and the shape of the spray are changed. Therefore, even if the injection amount changes in proportion to the engine load, the desired spray form can be realized by changing the fuel pressure. . Further, the spray shape is a wide dispersion type in which a plurality of sprays extend in the ejection direction and are separated from each other, a concentrated type in which a plurality of sprays are brought together under negative pressure and united to form a single united spray in the center, Centralized type, where a wide dispersion type and the united type are mixed,
The three types can be changed. Also, the fuel pressure
Engine high at low load, high in the engine load, low in the engine high load, since it is controlled, when the injection injection amount is and the fuel pressure is high at small formation spray centralized the combined type with wide distributed mixed When the injection amount is medium to large and the fuel pressure is low, a wide dispersion type spray is formed, and when the injection amount is medium to large and the fuel pressure is high, a concentrated spray having a single united spray is formed. As a result, it is possible to generate an optimal spray form according to the engine load. According to the fuel injection valve of the second aspect, the forming direction of the spray is
Wide range dispersion type corresponding to (α, α + θ) and (α + θ /
It can be changed to a centralized type corresponding to 2).

[Brief description of the drawings]

FIG. 1 is a sectional view of a tip portion of a fuel injection valve according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of the fuel injection valve of FIG.

3 is a side view of each state in which the spray from the fuel injection valve in FIG. 1 changes according to the injection amount and the fuel pressure.

4 is a diagram showing an internal combustion engine equipped with the fuel injection valve of FIG. 1 and a control system thereof.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fuel injection valve 4a, 4b Slit-shaped injection hole 11a Caby 17 ECU

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) F02M 61/18 320 F02M 61/18 330 F02M 61/18 360 F02D 41/04 325 F02D 41/32

Claims (2)

(57) [Claims] 1. A fuel injection valve having a plurality of slit-shaped injection holes , wherein the plurality of slit-shaped injection holes are provided on one side of a fuel injection valve shaft core.
And the plurality of slit-shaped injection holes are opposed to the axis of the fuel injection valve.
Formed from the fuel injection valve shaft center of the plurality of slit-shaped injection holes.
And the angle of the injection holes is set in the range of 10 to 50 ° so that the spray shape changes due to the change of the fuel pressure. When the engine is under a high load, the fuel injection amount is large. Therefore, the fuel pressure is lowered and the spray shape is a wide dispersion type in which multiple sprays extend in the injection direction and are separated from each other.When the engine is at medium load, the fuel pressure is increased because the fuel injection amount is medium and the spray is increased The shape is a centralized type, in which multiple sprays are brought together under negative pressure and united to form a single united spray at the center. A fuel injection valve, wherein the wide dispersion type and the centralized type of the single united spray are mixed. 2. There are two slit-shaped injection holes, one of which is inclined at an angle α from the axis of the fuel injection valve, and the other is one.
2. The fuel injection valve according to claim 1, wherein, when the two injection holes are inclined at an angle of [alpha] + [theta] from the fuel injection valve axis, the spray forming direction is changed to ([alpha], [alpha] + [theta]) and ([alpha] + [theta] / 2). .