JP2014194202A - Fuel injection nozzle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent lowering of a flow rate coefficient even when an injection pressure is increased, in a fuel injection nozzle for injecting a fuel into an internal combustion engine.SOLUTION: With respect to a limit value Q defined as an upper limit of a flow rate of fuel passing through a single injection hole, for example, in a nozzle including a first structure, the limit value Q is determined so as to satisfy an inequality 20 cc/min.≤Q≤339 cc/min., so that a flow rate coefficient Cd can be made 0.82 or more even when an injection pressure is increased to 220 MPa. Further by determining the limit value Q so as to satisfy an inequality 20 cc/min.≤Q≤302 cc/min., the flow rate coefficient Cd can be made 0.82 or more even when the injection pressure is increased to 240 Mpa. Furthermore by determining the limit value Q so as to satisfy an inequality 20 cc/min.≤Q≤240 cc/min., the flow rate coefficient Cd can be made 0.82 or more even when the injection pressure is increased to 260 Mpa.

Description

  The present invention relates to a fuel injection nozzle for injecting fuel (hereinafter sometimes abbreviated as a nozzle).

  2. Description of the Related Art Conventionally, for example, a fuel injection valve that injects and supplies fuel to an internal combustion engine includes a nozzle that injects fuel and an actuator that drives to open or close the nozzle. Further, a nozzle (fuel injection nozzle) used for a fuel injection valve is known that includes a cylindrical nozzle body and a needle that is accommodated in the inner periphery of the nozzle body so as to be movable in the axial direction. . The nozzle starts or stops fuel injection as the needle moves in the axial direction on the inner periphery of the nozzle body.

  That is, the inner wall of the nozzle body is provided with a seat position where the seat portion provided near the tip of the needle in the axial direction is separated, and further, the inner wall on the tip end side in the axial direction from the seat position is provided with fuel. A plurality of nozzle holes are opened. Then, when the seat portion is separated from the seat position, the fuel is guided from the inner periphery of the nozzle body to the outside through the injection hole (for example, see Patent Document 1).

By the way, in the fuel injection nozzle, in order to adopt an energy advantageous structure, various studies for increasing the flow coefficient have been made.
However, since the flow coefficient of the fuel injection nozzle decreases as the injection pressure increases, the higher the injection pressure, the more disadvantageous in terms of energy. For this reason, for example, a fuel injection valve that directly injects fuel into a cylinder of a diesel engine, such as a fuel injection valve that requires high injection pressure, a structure that does not decrease the flow coefficient even when the injection pressure is increased is required. Yes.

  Note that Patent Document 1 describes that the properties of spraying can be suitably improved by making the opening edge of the inner wall of the nozzle hole a curved surface. Further, Patent Document 2 describes that the friction loss can be reduced by providing the nozzle hole so as to satisfy a specific mathematical expression regarding the radius r of the nozzle hole and the distance (L) from the opening on the inner wall. Has been. However, by adopting the structures of Patent Documents 1 and 2, it is completely unknown how much effect can be obtained in response to the recent demand for higher injection pressure. .

JP 2010-180763 A JP 2001-182641 A

  The present invention has been made to solve the above-described problems, and an object of the present invention is to prevent a flow coefficient from being lowered even if the injection pressure is increased in a fuel injection nozzle that injects fuel into an internal combustion engine.

  According to the first invention of the present application, the fuel injection nozzle includes a cylindrical nozzle body and a needle that is accommodated in the inner periphery of the nozzle body so as to be movable in the axial direction. The fuel injection is started or stopped by moving in the axial direction around the circumference. The fuel injection nozzle includes a next seat position, an injection hole, and a first structure.

  First, the seat position is a part of the inner wall of the nozzle body, and the seat portion provided near the tip in the axial direction of the needle is detached. The nozzle hole opens in the inner wall of the nozzle body on the tip end side in the axial direction from the seat position, and guides the fuel from the inner periphery of the nozzle body to the outside by the seat portion being separated from the seat position.

  Further, the first structure is a structure that defines the shape of the wall portion in the inner wall where the seat position and the opening (11a) in the inner wall of the nozzle hole are present. According to the first structure, the sheet surface including the sheet position in the wall portion is provided as a conical surface coaxial with the axis (β) and has a smaller diameter toward the tip end in the axial direction, and the tip is a circle. is there. The nozzle hole opening surface, which is a portion including the opening (11a), is a cylindrical surface that is coaxial with the axis (β) and has a diameter equal to or smaller than the diameter of the front end of the sheet surface, or the front end side in the axial direction of the cylindrical surface And a hemispherical surface having the same diameter as that of the cylindrical surface and forming a convex on the tip side in the axial direction.

  And according to 1st invention of this application, a fuel injection nozzle satisfy | fills an inequality 20cc / min <= Q <= 339cc / min regarding the upper limit (Q) of the flow volume of the fuel which passes a single nozzle hole.

Thereby, even if it raises an injection pressure to 220 Mpa in the nozzle provided with a 1st structure, the flow coefficient Cd can be 0.82 or more. The flow coefficient Cd is defined by the following formula 1.
[Formula 1] q = Cd · A · (2 · Pdif / ρ) ^1/2
Here, q is the amount of fuel injected from a single injection hole, A is the cross-sectional area of the outlet of the injection hole, and Pdif is the space in which the injection pressure and fuel are injected (internal combustion engine) And ρ is the density of the fuel (the units of q, A, Pdif and ρ are MKS unit systems).

  That is, according to the earnest study by the present inventors, the upper limit value (Q) is set to 339 cc / min in the nozzle having the first structure (that is, the limit value (Q) is set to 339 cc / min or less). Thus, it was confirmed that the flow coefficient Cd was 0.82 or more in the range where the injection pressure was 220 MPa or less.

Further, the lower limit of the limit value (Q), 20 cc / min, is determined based on whether or not a single injection hole with a limit value (Q) of less than 20 cc / min can be provided. is there.
That is, the smaller the limit value (Q), the smaller the hole diameter of the nozzle hole, making it difficult to provide by electric discharge machining or laser machining. It is extremely difficult to provide a single nozzle hole with a limit value (Q) of less than 20 cc / min.

  As described above, in the nozzle having the first structure, by setting the limit value (Q) so as to satisfy the inequality 20 cc / min ≦ Q ≦ 339 cc / min, the flow coefficient Cd becomes 0. It can be 82 or more.

According to the second invention subordinate to the first invention of the present application, the fuel injection nozzle satisfies the inequality 20 cc / min ≦ Q ≦ 302 cc / min with respect to the limit value (Q).
According to the earnest study by the present inventors, the upper limit value (Q) is set to 302 cc / min in the nozzle having the first structure (that is, the limit value (Q) is set to 302 cc / min or less). It was confirmed that the flow coefficient Cd was 0.82 or more when the injection pressure was 240 MPa or less.

  For this reason, in the nozzle having the first structure, by setting the limit value (Q) so as to satisfy the inequality 20 cc / min ≦ Q ≦ 302 cc / min, the flow coefficient Cd is set to 0. 0 even if the injection pressure is increased to 240 MPa. It can be 82 or more.

According to the third invention subordinate to the second invention of the present application, the fuel injection nozzle satisfies the inequality 20 cc / min ≦ Q ≦ 240 cc / min with respect to the limit value (Q).
According to the diligent study of the present inventors, by setting the upper limit value (Q) to 240 cc / min in the nozzle having the first structure (that is, by setting the limit value (Q) to 240 cc / min or less). It was confirmed that the flow coefficient Cd was 0.82 or more when the injection pressure was 260 MPa or less.

  For this reason, in the nozzle having the first structure, by setting the limit value (Q) so as to satisfy the inequality 20 cc / min ≦ Q ≦ 240 cc / min, the flow coefficient Cd becomes 0. It can be 82 or more.

According to the fourth invention of the present application, the fuel injection nozzle includes the following second structure.
Here, according to the second structure, the sheet surface including the sheet position in the wall portion is provided as a conical surface coaxial with the axis (β) and has a smaller diameter toward the front end in the axial direction, and the opening (11a ) Is also present on the sheet surface.
According to the fourth aspect of the present invention, the fuel injection nozzle satisfies the inequality 20 cc / min ≦ Q ≦ 320 cc / min with respect to the limit value (Q).

That is, according to the earnest study by the present inventors, the upper limit value (Q) is set to 320 cc / min in the nozzle having the second structure (that is, the limit value (Q) is set to 320 cc / min or less). Thus, it was confirmed that the flow coefficient Cd was 0.82 or more in the range where the injection pressure was 220 MPa or less.
Thereby, in the nozzle having the second structure, the flow rate coefficient Cd is set to 0. 0 even if the injection pressure is increased to 220 MPa by setting the limit value (Q) so as to satisfy the inequality 20 cc / min ≦ Q ≦ 320 cc / min. It can be 82 or more.

According to a fifth invention subordinate to the fourth invention of the present application, the fuel injection nozzle satisfies the inequality 20 cc / min ≦ Q ≦ 288 cc / min with respect to the limit value (Q).
According to the diligent study by the present inventors, by setting the upper limit value (Q) to 288 cc / min in a nozzle having the second structure (that is, by setting the limit value (Q) to 288 cc / min or less). It was confirmed that the flow coefficient Cd was 0.82 or more when the injection pressure was 240 MPa or less.

  For this reason, in the nozzle having the second structure, by setting the limit value (Q) so as to satisfy the inequality 20 cc / min ≦ Q ≦ 288 cc / min, the flow coefficient Cd is reduced to 0. 0 even if the injection pressure is increased to 240 MPa. It can be 82 or more.

According to a sixth invention subordinate to the fifth invention of the present application, the fuel injection nozzle satisfies the inequality 20 cc / min ≦ Q ≦ 230 cc / min with respect to the limit value (Q).
According to the earnest study by the present inventors, by setting the upper limit value (Q) to 230 cc / min in the nozzle having the second structure (that is, by setting the limit value (Q) to 230 cc / min or less). It was confirmed that the flow coefficient Cd was 0.82 or more when the injection pressure was 260 MPa or less.

  For this reason, in the nozzle having the second structure, by setting the limit value (Q) so as to satisfy the inequality 20 cc / min ≦ Q ≦ 230 cc / min, the flow coefficient Cd becomes 0. It can be 82 or more.

According to the seventh invention of the present application, the fuel injection nozzle has the following third structure.
Here, according to the third structure, the sheet surface including the sheet position in the wall portion is provided as a conical surface coaxial with the axis (β) and has a smaller diameter toward the tip end in the axial direction, and the tip is circular. It is. In addition, the nozzle hole opening surface, which is a portion including the opening (11a), is formed as a conical surface having an angle formed between the axis (β) and the generatrix smaller than that of the seat surface and coaxial with the axis (β). The smaller the diameter, the closer to the tip end in the axial direction.
And according to 7th invention of this application, a fuel-injection nozzle satisfy | fills inequality 20cc / min <= Q <= 332cc / min regarding a limit value (Q).

That is, according to the earnest study by the present inventors, the upper limit value (Q) is set to 332 cc / min in the nozzle having the third structure (that is, the limit value (Q) is set to 332 cc / min or less). Thus, it was confirmed that the flow coefficient Cd was 0.82 or more in the range where the injection pressure was 220 MPa or less.
Thus, in the nozzle having the third structure, the flow coefficient Cd is set to 0. 0 even if the injection pressure is increased to 220 MPa by setting the limit value (Q) so as to satisfy the inequality 20 cc / min ≦ Q ≦ 332 cc / min. It can be 82 or more.

According to an eighth invention that is dependent on the seventh invention of the present application, the fuel injection nozzle satisfies the inequality 20 cc / min ≦ Q ≦ 299 cc / min with respect to the limit value (Q).
According to the earnest study by the present inventors, by setting the upper limit value (Q) to 299 cc / min in the nozzle having the third structure (that is, by setting the limit value (Q) to 299 cc / min or less). It was confirmed that the flow coefficient Cd was 0.82 or more when the injection pressure was 240 MPa or less.

  For this reason, in the nozzle having the third structure, by setting the limit value (Q) so as to satisfy the inequality 20 cc / min ≦ Q ≦ 299 cc / min, the flow coefficient Cd becomes 0. It can be 82 or more.

According to the ninth invention subordinate to the eighth invention of the present application, the fuel injection nozzle satisfies the inequality 20 cc / min ≦ Q ≦ 239 cc / min with respect to the limit value (Q).
According to the earnest study by the present inventors, by setting the upper limit value (Q) to 239 cc / min in the nozzle having the third structure (that is, by setting the limit value (Q) to 239 cc / min or less). It was confirmed that the flow coefficient Cd was 0.82 or more when the injection pressure was 260 MPa or less.

  For this reason, in the nozzle having the third structure, by setting the limit value (Q) so as to satisfy the inequality 20 cc / min ≦ Q ≦ 239 cc / min, the flow coefficient Cd becomes 0. It can be 82 or more.

It is sectional drawing which shows the whole fuel-injection nozzle (Examples 1-15 and Comparative Examples 1-6). It is a fragmentary sectional view showing the important section of a fuel injection nozzle (Examples 1-15 and comparative examples 1-6). It is a characteristic view which shows the correlation of the limit value Q, the injection pressure, and the flow coefficient Cd (Examples 1-15 and Comparative Examples 1-6). It is a fragmentary sectional view showing an important section of a fuel injection nozzle (Examples 16-30 and comparative examples 7-12). It is a characteristic view which shows the correlation of the limit value Q, the injection pressure, and the flow coefficient Cd (Examples 16-30 and Comparative Examples 7-12). It is a fragmentary sectional view which shows the principal part of a fuel-injection nozzle (Examples 31-45 and Comparative Examples 13-18). It is a characteristic view which shows the correlation of the limit value Q, the injection pressure, and the flow coefficient Cd (Examples 31-45 and Comparative Examples 13-18).

Hereinafter, the form for inventing is demonstrated based on the following Examples 1-45 and Comparative Examples 1-18.
In addition, the fuel injection nozzles of Examples 1 to 15 and Comparative Examples 1 to 6 (hereinafter sometimes referred to as nozzles) have a first structure to be described later with respect to the inner wall near the tip of the nozzle body. Examples 1 to 15 and Comparative Examples 1 to 6 may be collectively referred to as a first group.

In addition, the nozzles of Examples 16 to 30 and Comparative Examples 7 to 12 have the second structure described later with respect to the inner wall near the tip of the nozzle body, and Examples 16 to 30 and Comparative Examples 7 to 12 are summarized. Sometimes called the second group.
Furthermore, the nozzles of Examples 31 to 45 and Comparative Examples 13 to 18 have a third structure described later with respect to the inner wall near the tip of the nozzle body, and Examples 31 to 45 and Comparative Examples 13 to 18 are summarized. Sometimes called the third group.

[Configuration of the first group]
The configuration of the first group of nozzles 1 will be described with reference to the drawings.
In the first group, the nozzles 1 of Examples 1 to 15 and Comparative Examples 1 to 6 are different from each other in terms of a limit value Q and an injection pressure described later.
The nozzle 1 is opened to inject fuel, and constitutes a fuel injection valve together with an actuator (not shown) that drives the nozzle 1 to open or close. The fuel injection valve is mounted on, for example, an internal combustion engine (not shown), and is used to directly inject high-pressure fuel exceeding 100 MPa into the cylinder.

The actuator drives the valve body by increasing / decreasing the back pressure acting on the valve body (needle 2 described later) of the nozzle 1, for example, and generates magnetism by energizing a coil (not shown). The back pressure is increased or decreased by opening and closing a back pressure chamber (not shown) using force.
The fuel injection valve is, for example, a fuel supply pump (not shown) that discharges the fuel at a high pressure, and a pressure accumulation container (not shown) that accumulates the fuel discharged from the fuel supply pump in a high pressure state. At the same time, an accumulator fuel supply device is constructed, and high-pressure fuel is distributed from the accumulator vessel and injected into the cylinder.

  As shown in FIG. 1, the nozzle 1 includes a cylindrical nozzle body 3 and a needle 2 as a valve body that is accommodated in the inner periphery of the nozzle body 3 so as to be movable in the axial direction. The nozzle 1 starts or stops fuel injection when the needle 2 moves in the axial direction on the inner periphery of the nozzle body 3.

Here, the needle 2 has a sliding shaft portion 2a that is slidably supported in the axial direction by the nozzle body 3, and a conical tip portion 2b that substantially functions as a valve portion. A cylindrical portion 2c that is long in the axial direction is formed between the portion 2a and the tip portion 2b.
The inner periphery of the nozzle body 3 has a cylindrical shape that is long in the axial direction, and the tip is closed. A part of the inner periphery of the nozzle body 3 is locally enlarged in the radial direction to form a fuel reservoir 4 in which fuel to be injected is temporarily stored.

  A region on the axially rear end side of the fuel reservoir 4 in the inner periphery of the nozzle body 3 forms a sliding hole 5 for slidably supporting the sliding shaft portion 2a. The region on the front end side in the direction accommodates the front end portion 2b and the cylindrical portion 2c to form an annular cylindrical fuel passage 6. In addition, a fuel passage 7 for guiding the fuel received from the pressure accumulating vessel to the fuel reservoir 4 is connected to the fuel reservoir 4 separately in the nozzle body 3.

Hereinafter, a characteristic configuration of the nozzle 1 will be described with reference to FIG.
As a characteristic configuration, the nozzle 1 includes a sheet position 10 and an injection hole 11, and further includes a first structure that defines the shape of the inner wall near the tip of the nozzle body 3. The nozzle 1 is set with various numerical values with respect to a limit value Q described later.

First, the sheet position 10 is a part of the inner wall near the tip of the nozzle body 3, and the sheet portion 13 provided at the tip 2b is detached.
Here, the outer peripheral surface of the front end portion 2b is, for example, one in which three different conical surfaces 14a, 14b, and 14c are coaxially continuous from the front end to the axial rear end side, and the conical surfaces 14a to 14c are the respective buses. The angle formed between the needle 2 and the axis α of the needle 2 increases toward the distal end side. The intersecting line 15a between the conical surfaces 14a and 14b and the intersecting line 15b between the conical surfaces 14b and 14c are circles perpendicular to the axis α, the intersecting line 15b functions as the sheet portion 13, and the sheet position 10 is circular. It is.

  Further, the nozzle hole 11 opens to the inner wall of the nozzle body 3 on the tip end side in the axial direction with respect to the sheet position 10, and the seat portion 13 is separated from the sheet position 10, so that fuel flows from the inner periphery of the nozzle body 3 to the outside. Lead. That is, when the seat portion 13 is separated from the seat position 10, a gap is formed between the seat portion 13 and the seat position 10, and fuel is introduced from the fuel passage 6 into the nozzle hole 11 through this gap. Injected to the outside of the nozzle body 3.

  In addition, the first structure is a nozzle surface that is a portion including an opening 11a of the nozzle hole 11 in the inner wall of the nozzle body 3 and a sheet surface that is a portion including the sheet position 10 in the inner wall near the tip of the nozzle body 3. It defines the relationship with the opening surface. More specifically, according to the first structure, the sheet surface and the nozzle hole opening surface are defined as follows. First, the sheet surface is provided as a conical surface that is coaxial with the axis β and has a smaller diameter toward the tip end in the axial direction, and the tip is a circle. Further, the nozzle hole opening surface is coaxial with the axis β and has a diameter equal to or less than the diameter of the front end of the sheet surface, or is continuous with the front end side in the axial direction of the cylindrical surface, and the diameter of the cylindrical surface It is a hemispherical surface having the same diameter and forming a convex on the tip side in the axial direction.

More specifically, the inner wall in the vicinity of the tip of the nozzle body 3 has the following conical surface 17, cylindrical surface 18, and hemispherical surface 19, and the inner peripheral tip of the nozzle body 3 is closed in a bag shape.
The conical surface 17 is provided coaxially with the axis β, has a smaller diameter toward the tip in the axial direction, and has a circle 20 at the tip. The conical surface 17 is a seat surface including the seat position 10.

  Moreover, the cylindrical surface 18 is provided coaxially with the axis β, has the same diameter as the circle 20, and continues from the circle 20 to the tip side in the axial direction. Further, the hemispherical surface 19 has the same diameter as the cylindrical surface 18 and is continuous with the cylindrical surface 18 so as to form a convex on the tip end side in the axial direction. And the opening 11a is provided so that the cylindrical surface 18 and the hemispherical surface 19 may be straddled, and the cylindrical surface 18 and the hemispherical surface 19 are nozzle hole opening surfaces.

Next, the limit value Q will be described.
The limit value Q is defined as the upper limit of the flow rate of the fuel passing through the single nozzle hole 11. Then, the limit value Q and the injection pressure are changed as parameters to obtain Examples 1 to 15 and Comparative Examples 1 to 6, and the respective nozzles 1 of Examples 1 to 15 and Comparative Examples 1 to 6 are defined by Formula 1. The numerical value of the flow coefficient Cd is determined. The injection pressure is the pressure of the fuel injected from the nozzle hole 11 and substantially coincides with the pressure indicated by the fuel in the fuel reservoir 4, the fuel passages 5 and 6, or the pressure accumulating vessel.

The survey results are shown in Table 1 below. Note that three numerical values of 220 MPa, 240 MPa, and 260 MPa are used for the injection pressure. Specifically, Examples 1 to 5 and Comparative Examples 1 and 2 have an injection pressure of 220 MPa, Examples 6 to 10 and Comparative Examples 3 and 4 have an injection pressure of 240 MPa. In Examples 11 to 15 and Comparative Examples 5 and 6, the injection pressure was 260 MPa.
[Table 1]

Further, the limit value Q and the flow coefficient Cd are taken on the horizontal axis and the vertical axis, respectively, and the shape of the mark is changed for each of the three numerical values of the injection pressure, and the result of Table 1 is shown in the graph of FIG.
As a result, it has been found that the correlation between the limit value Q and the flow coefficient Cd draws a different curve for each numerical value of the injection pressure, and that the curve with the higher injection pressure appears on the left side of the figure (the smaller side of the limit value Q). It has also been found that each curve can be approximated by a quadratic function having a convexity upward (a quadratic function in which the quadratic term has a negative coefficient).

  Therefore, the correlation between the limit value Q and the flow coefficient Cd was obtained as a quadratic function for each of the three injection pressures. Furthermore, a numerical value 0.82 that can be allowed as the lower limit of the flow coefficient Cd is applied to each of these three quadratic functions, and the numerical value of the limit value Q when the flow coefficient Cd becomes 0.82 is set for each injection pressure. Asked. The numerical value of the limit value Q obtained by this calculation was 339 cc / min, 302 cc / min, and 240 cc / min in the respective correlations of the injection pressures 220, 240, and 260 MPa.

  As a result, in the nozzle 1 having the first structure, by setting the upper limit value Q to 339 cc / min (that is, by setting the limit value Q to 339 cc / min or less), the injection pressure is in the range of 220 MPa or less. It was confirmed that the flow coefficient Cd was 0.82 or more. Further, when the upper limit value Q is set to 302 cc / min (that is, the limit value Q is set to 302 cc / min or less), the flow coefficient Cd is 0.82 or more when the injection pressure is 240 MPa or less. I was able to confirm that Furthermore, by setting the upper limit of the limit value Q to 240 cc / min (that is, by setting the limit value Q to 240 cc / min or less), the flow coefficient Cd is 0.82 or more when the injection pressure is 260 MPa or less. I was able to confirm that

[Effects of Examples 1 to 15]
According to the nozzles 1 of Examples 1 to 5, the limit value Q satisfied the inequality Q ≦ 339 cc / min, the injection pressure was 220 MPa, and the flow coefficient Cd was 0.82 or more. Further, according to the nozzle 1 of Comparative Examples 1 and 2, the limit value Q was larger than 339 cc / min, the injection pressure was 220 MPa, and the flow coefficient Cd was less than 0.82.
Thereby, in the nozzle 1 having the first structure, the flow rate coefficient Cd is set to 0.82 or more even if the injection pressure is increased to 220 MPa by setting the limit value Q so as to satisfy the inequality Q ≦ 339 cc / min. be able to.

  In addition, the lower limit of the limit value Q is determined based on whether or not the single injection hole 11 with which the limit value Q is less than the lower limit numerical value can be provided. That is, the smaller the limit value Q is, the smaller the hole diameter of the nozzle hole 11 becomes, and it becomes difficult to provide it by electric discharge machining or laser machining. From this viewpoint, the lower limit of the limit value Q can be set to 20 cc / min, for example.

  As described above, in the nozzle 1 having the first structure, by setting the limit value Q so as to satisfy the inequality 20 cc / min ≦ Q ≦ 339 cc / min, the flow coefficient Cd is 0.82 even if the injection pressure is increased to 220 MPa. This can be done.

According to the nozzles 1 of Examples 6 to 10, the limit value Q satisfied the inequality 20 cc / min ≦ Q ≦ 302 cc / min, the injection pressure was 240 MPa, and the flow coefficient Cd was 0.82 or more. Further, according to the nozzle 1 of Comparative Examples 3 and 4, the limit value Q was larger than 302 cc / min, the injection pressure was 240 MPa, and the flow coefficient Cd was less than 0.82.
Thus, in the nozzle 1 having the first structure, the flow rate coefficient Cd is set to 0.82 even if the injection pressure is increased to 240 MPa by setting the limit value Q so as to satisfy the inequality 20 cc / min ≦ Q ≦ 302 cc / min. This can be done.

According to the nozzles 1 of Examples 11 to 15, the limit value Q satisfied the inequality 20 cc / min ≦ Q ≦ 240 cc / min, the injection pressure was 260 MPa, and the flow coefficient Cd was 0.82 or more. Further, according to the nozzles 1 of Comparative Examples 5 and 6, the limit value Q was larger than 240 cc / min, the injection pressure was 260 MPa, and the flow coefficient Cd was less than 0.82.
Thereby, in the nozzle 1 having the first structure, the flow rate coefficient Cd is set to 0.82 even if the injection pressure is increased to 260 MPa by setting the limit value Q so as to satisfy the inequality 20 cc / min ≦ Q ≦ 240 cc / min. This can be done.

[Configuration of the second group]
The configuration of the second group of nozzles 1 will be described with reference to FIG.
In the second group, the nozzles 1 of Examples 16 to 30 and Comparative Examples 7 to 12 are different from each other in terms of the limit value Q and the injection pressure.
The second group of nozzles 1 includes the following second structure as a structure that defines the shape of the inner wall near the tip of the nozzle body 3.

  Here, as in the first structure, the second structure defines the relationship between the sheet surface and the nozzle hole opening surface. However, according to the second structure, the sheet surface and the jet are shown in FIG. The hole opening surface is a common conical surface 17, and both the sheet position 10 and the opening 11 a exist in the common conical surface 17.

That is, the second structure is such that the seat surface is provided as a conical surface 17 coaxial with the axis β, the diameter is smaller toward the tip end side in the axial direction, and the opening 11a exists in the seat surface.
According to the nozzle 1 of the second embodiment, the inner wall in the vicinity of the tip of the nozzle body 3 does not have portions corresponding to the cylindrical surface 18 and the hemispherical surface 19 existing in the nozzle 1 of the first group 1. A relief 22 by grinding is formed at the circumferential tip.

Next, the limit value Q of the second group will be described.
In the second group, the limit value Q and the injection pressure are changed as parameters to obtain Examples 16 to 30 and Comparative Examples 7 to 12, and the flow coefficient Cd in each nozzle 1 of Examples 16 to 30 and Comparative Examples 7 to 12 is set. Was investigated.

The survey results are shown in Table 2 below. Note that three numerical values of 220 MPa, 240 MPa, and 260 MPa are used for the injection pressure. Specifically, Examples 16 to 20 and Comparative Examples 7 and 8 have an injection pressure of 220 MPa, and Examples 21 to 25 and Comparative Examples 9 and 10 have an injection pressure of 240 MPa. Examples 26 to 30 and Comparative Examples 11 and 12 have an injection pressure of 260 MPa.
[Table 2]

Further, the limit value Q and the flow coefficient Cd are taken on the horizontal axis and the vertical axis, respectively, and the shape of the mark is changed for each of the three numerical values of the injection pressure, and the results of Table 2 are shown in the graph of FIG.
As a result, it has been found that the correlation between the limit value Q and the flow coefficient Cd draws a different curve for each numerical value of the injection pressure, and that the curve with the higher injection pressure appears on the left side of the figure (the smaller side of the limit value Q). Further, it has been found that each curve can be approximated by a quadratic function having an upward convexity.

  Then, as in the first group, the correlation between the limit value Q and the flow coefficient Cd is obtained as a quadratic function for each of the three injection pressures, and the flow coefficient Cd becomes 0.82 from each of these three quadratic functions. The numerical value of the limit value Q was determined for each injection pressure. The numerical value of the limit value Q obtained by this calculation was 320 cc / min, 288 cc / min, and 230 cc / min in the correlation of the injection pressures 220, 240, and 260 MPa, respectively.

  As a result, in the nozzle 1 having the second structure, the upper limit value Q is set to 320 cc / min (that is, the limit value Q is set to 320 cc / min or less). It was confirmed that the flow coefficient Cd was 0.82 or more. Further, by setting the upper limit of limit value Q to 288 cc / min (that is, by setting limit value Q to 288 cc / min or less), in the range where the injection pressure is 240 MPa or less, the flow coefficient Cd is 0.82 or more. I was able to confirm that Furthermore, by setting the upper limit of the limit value Q to 230 cc / min (that is, by setting the limit value Q to 230 cc / min or less), the flow coefficient Cd is 0.82 or more when the injection pressure is 260 MPa or less. I was able to confirm that

[Effects of Examples 16 to 30]
According to the nozzles 1 of Examples 16 to 20, the limit value Q satisfied the inequality 20 cc / min ≦ Q ≦ 320 cc / min, the injection pressure was 220 MPa, and the flow coefficient Cd was 0.82 or more. Further, according to the nozzles 1 of Comparative Examples 7 and 8, the limit value Q was larger than 320 cc / min, the injection pressure was 220 MPa, and the flow coefficient Cd was less than 0.82.
Thereby, in the nozzle 1 having the second structure, the flow rate coefficient Cd is set to 0. 0 even if the injection pressure is increased to 220 MPa by setting the limit value Q so as to satisfy the inequality 20 cc / min ≦ Q ≦ 320 cc / min. It can be 82 or more.

According to the nozzles 1 of Examples 21 to 25, the limit value Q satisfied the inequality 20 cc / min ≦ Q ≦ 288 cc / min, the injection pressure was 240 MPa, and the flow coefficient Cd was 0.82 or more. Further, according to the nozzle 1 of Comparative Examples 9 and 10, the limit value Q was larger than 288 cc / min, the injection pressure was 240 MPa, and the flow coefficient Cd was less than 0.82.
Thereby, in the nozzle 1 having the second structure, the flow rate coefficient Cd is set to 0.82 even if the injection pressure is increased to 240 MPa by setting the limit value Q so as to satisfy the inequality 20 cc / min ≦ Q ≦ 288 cc / min. This can be done.

According to the nozzles 1 of Examples 26 to 30, the limit value Q satisfied the inequality 20 cc / min ≦ Q ≦ 230 cc / min, the injection pressure was 260 MPa, and the flow coefficient Cd was 0.82 or more. Further, according to the nozzles 1 of Comparative Examples 11 and 12, the limit value Q was larger than 230 cc / min, the injection pressure was 260 MPa, and the flow coefficient Cd was less than 0.82.
Accordingly, in the nozzle 1 having the second structure, the flow rate coefficient Cd is set to 0.82 even if the injection pressure is increased to 260 MPa by setting the limit value Q so as to satisfy the inequality 20 cc / min ≦ Q ≦ 230 cc / min. This can be done.

[Configuration of the third group]
The configuration of the third group of nozzles 1 will be described with reference to FIG.
In the third group, the nozzles 1 of Examples 31 to 45 and Comparative Examples 13 to 18 are different from each other in terms of the limit value Q and the injection pressure.
The third group of nozzles 1 includes the following third structure as a structure that defines the shape of the inner wall near the tip of the nozzle body 3.

  Here, the third structure defines the relationship between the sheet surface and the nozzle hole opening surface as in the first and second structures, but according to the third structure, the sheet surface and the nozzle hole opening surface. Are two different conical surfaces. More specifically, according to the third structure, the sheet surface and the nozzle hole opening surface are defined as follows. That is, according to the third structure, the seat surface is provided as a conical surface coaxial with the axis β, and has a smaller diameter toward the tip end side in the axial direction, and the tip end is a circle. Further, the nozzle hole opening surface has an angle formed between the axis β and the generatrix smaller than that of the seat surface, and is provided as a conical surface coaxial with the axis β and has a smaller diameter toward the tip end in the axial direction.

More specifically, as shown in FIG. 6, the inner wall in the vicinity of the tip of the nozzle body 3 has the following first and second conical surfaces 17a and 17b.
The first and second conical surfaces 17a and 17b are coaxial with the axis β, and the first conical surface 17a has a smaller diameter toward the tip end in the axial direction and a tip 20 at the tip. Further, the second conical surface 17b is continuous with the tip end side in the axial direction of the circle 20, and the angle formed between the axis β and the generatrix is smaller than that of the first conical surface 17a.

The seat position 10 is provided on the first conical surface 17a, and the first conical surface 17a is a seat surface. The opening 11a is provided in the second conical surface 17b, and the second conical surface 17b is a nozzle hole opening surface.
According to the nozzle 1 of the third group, the inner wall near the tip of the nozzle body 3 does not have portions corresponding to the cylindrical surface 18 and the hemispherical surface 19 present in the nozzle 1 of the first group. The tip is closed by the third conical surface 17c.

Next, the limit value Q of the third group will be described.
In the third group, Examples 31 to 45 and Comparative Examples 13 to 18 are made by changing the limit value Q and the injection pressure as parameters, and the flow coefficient Cd is obtained in each nozzle 1 of Examples 31 to 45 and Comparative Examples 13 to 18. Was investigated.

The survey results are shown in Table 3 below. Note that three numerical values of 220 MPa, 240 MPa, and 260 MPa are used for the injection pressure. Specifically, Examples 31 to 35 and Comparative Examples 13 and 14 have an injection pressure of 220 MPa, Examples 36 to 40 and Comparative Examples 15 and 16 have an injection pressure of 240 MPa, and Examples 41 to 45 and Comparative Examples 17 and 18 have an injection pressure of 260 MPa.
[Table 3]

Further, the limit value Q and the flow coefficient Cd are taken on the horizontal axis and the vertical axis, respectively, and the shape of the mark is changed for each of the three numerical values of the injection pressure, and the result of Table 3 is shown in the graph of FIG.
As a result, it has been found that the correlation between the limit value Q and the flow coefficient Cd draws a different curve for each numerical value of the injection pressure, and that the curve with the higher injection pressure appears on the left side of the figure (the smaller side of the limit value Q). Further, it has been found that each curve can be approximated by a quadratic function having an upward convexity.

  Then, as in the first and second groups, the correlation between the limit value Q and the flow coefficient Cd is obtained as a quadratic function for each of the three injection pressures, and the flow coefficient Cd is 0. 0 from each of these three quadratic functions. The numerical value of the limit value Q when it becomes 82 was obtained for each injection pressure. The numerical value of the limit value Q obtained by this calculation was 332 cc / min, 299 cc / min, and 239 cc / min in the correlation of the injection pressures 220, 240, and 260 MPa, respectively.

  As a result, in the nozzle 1 having the third structure, the upper limit value Q is set to 332 cc / min (that is, the limit value Q is set to 332 cc / min or less). It was confirmed that the flow coefficient Cd was 0.82 or more. Further, by setting the upper limit of limit value Q to 299 cc / min (that is, by setting limit value Q to 299 cc / min or less), in the range where the injection pressure is 240 MPa or less, the flow coefficient Cd is 0.82 or more. I was able to confirm that Further, by setting the upper limit of the limit value Q to 239 cc / min (that is, by setting the limit value Q to 239 cc / min or less), the flow coefficient Cd is 0.82 or more when the injection pressure is 260 MPa or less. I was able to confirm that

[Effects of Examples 31 to 45]
According to the nozzles 1 of Examples 31 to 35, the limit value Q satisfied the inequality 20 cc / min ≦ Q ≦ 332 cc / min, the injection pressure was 220 MPa, and the flow coefficient Cd was 0.82 or more. Further, according to the nozzles 1 of Comparative Examples 13 and 14, the limit value Q was larger than 332 cc / min, the injection pressure was 220 MPa, and the flow coefficient Cd was less than 0.82.
Thus, in the nozzle 1 having the third structure, the limit value Q is set so as to satisfy the inequality 20 cc / min ≦ Q ≦ 332 cc / min. It can be 82 or more.

According to the nozzles 1 of Examples 36 to 40, the limit value Q satisfied the inequality 20 cc / min ≦ Q ≦ 299 cc / min, the injection pressure was 240 MPa, and the flow coefficient Cd was 0.82 or more. Further, according to the nozzles 1 of Comparative Examples 15 and 16, the limit value Q was larger than 299 cc / min, the injection pressure was 240 MPa, and the flow coefficient Cd was less than 0.82.
Thus, in the nozzle 1 having the third structure, the flow rate coefficient Cd is set to 0.82 even if the injection pressure is increased to 240 MPa by setting the limit value Q so as to satisfy the inequality 20 cc / min ≦ Q ≦ 299 cc / min. This can be done.

According to the nozzles 1 of Examples 41 to 45, the limit value Q satisfied the inequality 20 cc / min ≦ Q ≦ 239 cc / min, the injection pressure was 260 MPa, and the flow coefficient Cd was 0.82 or more. Further, according to the nozzles 1 of Comparative Examples 17 and 18, the limit value Q was larger than 239 cc / min, the injection pressure was 260 MPa, and the flow coefficient Cd was less than 0.82.
Thereby, in the nozzle 1 having the third structure, the flow rate coefficient Cd is set to 0.82 even if the injection pressure is increased to 260 MPa by setting the limit value Q so as to satisfy the inequality 20 cc / min ≦ Q ≦ 239 cc / min. This can be done.

[Modification]
The aspect of the nozzle 1 is not limited to an Example, A various modification can be considered. For example, in the nozzle 1 having the second structure, the tip of the sack chamber may be provided on a plane perpendicular to the axis β.

DESCRIPTION OF SYMBOLS 1 Nozzle (fuel injection nozzle) 2 Needle 3 Nozzle body 10 Seat position 11 Injection hole 11a Opening 13 Sheet part 17 Conical surface 18 Cylindrical surface 19 Hemispherical surface 20 yen Q Limit value β axis

Claims (9)

A cylindrical nozzle body (3) and a needle (2) accommodated in the inner periphery of the nozzle body (3) so as to be movable in the axial direction, the needle (2) being the nozzle body ( In the fuel injection nozzle (1) that starts or stops fuel injection by moving in the axial direction on the inner circumference of 3),
A seat position (10) at which a seat portion (13) that is a part of the inner wall of the nozzle body (3) and is provided near the tip of the needle (2) in the axial direction;
The nozzle body (3) is opened to the inner wall of the nozzle body (3) on the front end side in the axial direction from the sheet position (10), and the seat portion (13) is separated from the sheet position (10). Nozzle hole (11) for guiding fuel from the inner periphery to the outside;
Of the inner wall, the sheet position (10) and the structure of the wall portion where the opening (11a) in the inner wall of the injection hole (11) is defined, the seat position ( 10) is provided as a conical surface (17) coaxial with the axis (β) of the nozzle body (3), and the seat surface is smaller in diameter toward the tip end in the axial direction and the tip is a circle (20). The nozzle hole opening surface, which is a portion including the opening (11a), is a cylindrical surface (18) that is coaxial with the axis (β) and has a diameter equal to or smaller than the diameter of the front end of the sheet surface, or the cylindrical surface A first structure which is a hemispherical surface (19) which is continuous to the axial tip side of (18) and has a diameter the same as the diameter of the cylindrical surface (18) and forms a convex on the tip side in the axial direction With
A fuel injection nozzle (1) characterized by satisfying the inequality 20cc / min ≦ Q ≦ 339cc / min with respect to the upper limit value (Q) of the flow rate of fuel passing through the single nozzle hole (11). The fuel injection nozzle (1) according to claim 1,
The fuel injection nozzle (1) characterized by satisfying the inequality 20cc / min ≦ Q ≦ 302cc / min with respect to the limit value (Q). The fuel injection nozzle (1) according to claim 2,
The fuel injection nozzle (1) characterized by satisfying the inequality 20cc / min ≦ Q ≦ 240cc / min with respect to the limit value (Q). A cylindrical nozzle body (3) and a needle (2) accommodated in the inner periphery of the nozzle body (3) so as to be movable in the axial direction, the needle (2) being the nozzle body ( In the fuel injection nozzle (1) that starts or stops fuel injection by moving in the axial direction on the inner circumference of 3),
A seat position (10) at which a seat portion (13) that is a part of the inner wall of the nozzle body (3) and is provided near the tip of the needle (2) in the axial direction;
The nozzle body (3) is opened to the inner wall of the nozzle body (3) on the front end side in the axial direction from the sheet position (10), and the seat portion (13) is separated from the sheet position (10). Nozzle hole (11) for guiding fuel from the inner periphery to the outside;
Of the inner wall, the sheet position (10) and the structure of the wall portion where the opening (11a) in the inner wall of the injection hole (11) is defined, the seat position ( 10) is provided as a conical surface (17) coaxial with the axis (β) of the nozzle body (3) and has a smaller diameter toward the tip end in the axial direction, and the opening (11a) is also the sheet A second structure present on the surface,
A fuel injection nozzle (1) characterized by satisfying the inequality 20cc / min ≦ Q ≦ 320cc / min with respect to the upper limit value (Q) of the flow rate of fuel passing through the single nozzle hole (11). The fuel injection nozzle (1) according to claim 4,
The fuel injection nozzle (1) characterized by satisfying the inequality 20cc / min ≦ Q ≦ 288cc / min with respect to the limit value (Q). The fuel injection nozzle (1) according to claim 5,
The fuel injection nozzle (1) characterized by satisfying the inequality 20cc / min ≦ Q ≦ 230cc / min with respect to the limit value (Q). A cylindrical nozzle body (3) and a needle (2) accommodated in the inner periphery of the nozzle body (3) so as to be movable in the axial direction, the needle (2) being the nozzle body ( In the fuel injection nozzle (1) that starts or stops fuel injection by moving in the axial direction on the inner circumference of 3),
A seat position (10) at which a seat portion (13) that is a part of the inner wall of the nozzle body (3) and is provided near the tip of the needle (2) in the axial direction;
The nozzle body (3) is opened to the inner wall of the nozzle body (3) on the front end side in the axial direction from the sheet position (10), and the seat portion (13) is separated from the sheet position (10). Nozzle hole (11) for guiding fuel from the inner periphery to the outside;
Of the inner wall, the sheet position (10) and the structure of the wall portion where the opening (11a) in the inner wall of the injection hole (11) is defined, the seat position ( 10) is provided as a conical surface (17a) that is coaxial with the axis (β) of the nozzle body (3), and the seat surface is smaller in diameter toward the tip end in the axial direction and the tip is a circle (20). The nozzle hole opening surface, which is a portion including the opening (11a), has an angle formed between the axis (β) and the generatrix smaller than the seat surface and is coaxial with the axis (β). A third structure provided as a conical surface (17b) and having a smaller diameter toward the tip end in the axial direction;
A fuel injection nozzle (1) characterized by satisfying the inequality 20cc / min≤Q≤332cc / min with respect to the upper limit value (Q) of the flow rate of fuel passing through the single nozzle hole (11). The fuel injection nozzle (1) according to claim 7,
The fuel injection nozzle (1) characterized by satisfying the inequality 20cc / min ≦ Q ≦ 299cc / min with respect to the limit value (Q). The fuel injection nozzle (1) according to claim 8,
The fuel injection nozzle (1) characterized by satisfying the inequality 20cc / min ≦ Q ≦ 239cc / min with respect to the limit value (Q).

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