JP6428540B2 - Fuel injection device - Google Patents

Description

  The present invention relates to a fuel injection device that supplies fuel to an engine system such as a diesel engine.

2. Description of the Related Art Conventionally, a twin needle type fuel injection device that controls fuel injection by adjusting lift amounts of an outer needle and an inner needle accommodated coaxially in a housing is known.
On the other hand, a diesel cycle and a sabatate cycle having a constant pressure heating process are thermal cycles used for compression ignition engines such as medium-speed and high-speed diesel engines, and have excellent thermal efficiency. For this reason, since the diesel cycle and the sabatate cycle can extract a lot of kinetic energy with a small amount of fuel, the amount of carbon dioxide emission is small and it is environmentally friendly. Therefore, it is required to control the fuel injection amount with high accuracy in order to create a good combustion state by the diesel cycle or the sabatate cycle.

JP2009-062920A

  In the twin needle type fuel injection device having the configuration of Patent Document 1, the fuel injection amount is controlled by adjusting the pressure on the back side of the inner needle and the outer needle. For this reason, the fuel injection amount can be changed in two stages of the inner needle and the outer needle. However, since the fuel injection amount of the fuel injection device having this configuration is determined by the minimum flow path area of the first injection hole and the minimum flow path area of the second injection hole, it converges to a certain amount. When a certain amount of fuel is injected, combustion is not promoted in the constant pressure heating process of the diesel cycle or the sabatate cycle. For this reason, when the piston of the combustion chamber of the engine moves backward, that is, when the volume expands, there is a problem that the pressure is lowered despite the constant pressure heating process, and a good combustion state is not obtained.

  The present invention has been created in view of the above-mentioned problems, and its purpose is to control the fuel injection amount with high accuracy in an engine using a thermal cycle having a constant pressure heating process, thereby reducing the pressure drop in the constant pressure heating process. It is providing the fuel-injection apparatus which suppresses.

The present invention is a fuel injection device that controls the amount of fuel injected into a combustion chamber of an engine of an engine system, and includes a housing (10), an outer needle (38), and an inner needle (37).
The housing has a first nozzle hole (121) through which fuel is injected at the front end of the bottomed cylindrical shape, and a second nozzle hole (122) through which fuel is injected by being positioned on the rear end side of the first nozzle hole. And a housing collar (101).
The housing flange protrudes inward in the radial direction from the inner surface (102) of the housing.

The outer needle is slidably accommodated in the housing, and the second nozzle hole can be opened and closed in accordance with axial sliding. The inner side surface (391) of the side wall and the outer side surface (392) of the side wall are provided on the side wall. At least one communication hole.
The communication hole includes an inlet surface (382) on the outer peripheral side of the outer needle and an outlet surface (384) on the inner peripheral side of the outer needle, and communicates the inlet surface and the outlet surface. Further, the communication hole is formed on the front end side of the housing collar when the outer needle is closed.

The inner needle is slidably accommodated in the outer needle, can open and close the first nozzle hole in accordance with axial sliding, and has an inner needle collar (371).
The inner needle collar projects from the outer surface (372) of the inner needle outward in the radial direction. Further, the inner needle collar overlaps with the outlet surface of the communication hole when the inner needle is closed.

When the inner needle or the outer needle slides, the first flow path (27), the second flow path (28), the third flow path (29), which are flow paths constituted by the housing, the outer needle and the inner needle, An outlet hole channel (385) and an inlet hole channel (383) are formed.
The first channel is a channel formed between the outer surface of the inner needle and the inner surface of the outer needle, and the second channel is formed between the inner surface of the housing and the outer surface of the outer needle. It is a flow path. The third channel is a channel formed between the outer surface of the inner needle and the inner surface of the housing.

  The outlet hole channel is a channel formed by the inner needle collar and the outlet surface of the communication hole. The inlet hole channel is a channel formed by the housing flange and the inlet surface of the communication hole. When the inner needle and the outer needle are closed, the first channel communicates with the outlet hole channel and the inlet hole channel.

When the inner needle or the outer needle slides, that is, when the inner needle or the outer needle opens and closes, the inner needle collar portion passes along the outlet surface of the communication hole, and closes and opens the outlet hole channel. . At this time, the channel area of the outlet hole channel is changed.
The inner needle collar is formed such that when the inner needle slides, the rate of change of the channel area of the outlet hole channel is smaller than the rate of change of the channel area of the first channel. For this reason, the diameter of a housing, an inner needle, an inner needle collar part, an outer needle, and a communicating hole is set.

  The outlet hole channel is formed so that the channel area of the outlet hole channel is smaller than the channel area of the first nozzle hole when the inner needle and the outer needle are closed. This is because when the flow area of the first injection hole is larger than the flow area of the first injection hole, the fuel injection amount is determined by the flow area of the first injection hole.

When the outer needle slides, the housing collar passes along the inlet surface of the communication hole, and closes and opens the inlet hole channel. At this time, the channel area of the inlet hole channel is changed.
Further, the housing collar is formed such that when the outer needle slides, the rate of change of the channel area of the inlet hole channel is smaller than the rate of change of the channel area of the second channel. For this reason, the diameter of a housing, a housing collar part, an inner needle, an outer needle, and a communicating hole is set.

  In the present invention, the inner needle collar part and the housing collar part change the flow channel areas of the inlet hole channel and the outlet hole channel of the communication hole by sliding between the inner needle and the outer needle. Thereby, a flow path structure increases and the controllability of a flow path area improves. Since the fuel injection amount changes depending on the flow path area, the fuel injection amount can be continuously increased. Therefore, the fuel injection amount can be controlled with high accuracy, and the pressure drop in the constant pressure heating process of the thermal cycle can be suppressed.

Sectional drawing which shows the injector by 1st Embodiment. (A) II section enlarged view at the time of valve opening of the injector by 1st Embodiment, (b) IIb-IIb sectional view taken on the line of Fig.2 (a). (A) III part enlarged view at the time of valve closing of the injector by 1st Embodiment, (b) IIIb-IIIb sectional view taken on the line of Fig.3 (a). The IV section enlarged view at the time of valve opening of the injector by 1st Embodiment. The V section enlarged view at the time of valve closing of the injector by 1st Embodiment. The VI section enlarged view which the inner needle collar part of the injector by 1st Embodiment begins to pass through the exit surface of a communicating hole. The VII part enlarged view when the inner needle collar part of the injector by 1st Embodiment passes the exit surface of a communicating hole. The VIII part enlarged view when the inner needle collar part of the injector by 1st Embodiment passes the exit surface of a communicating hole. The IX part enlarged view after the inner needle collar part of the injector by 1st Embodiment passes the exit surface of a communicating hole. The X section enlarged view when the housing collar part of the injector by 1st Embodiment passes the entrance surface of a communicating hole. The XI section enlarged view when the housing collar part of the injector by 1st Embodiment passes the entrance surface of a communicating hole. The XII section enlarged view after the housing collar part of the injector by 1st Embodiment passes the entrance surface of a communicating hole. The change of the flow-path area of the injector by 1st Embodiment. The heat cycle figure of the Sabate cycle which has a constant pressure heating process. (A) Fuel injection amount of the injector according to the first embodiment (b) Constant pressure heating process of the XV section enlarged view by the injector of the first embodiment. Sectional drawing which shows the injector by 2nd Embodiment. The XVII part enlarged view which the inner needle collar part of the injector by 2nd Embodiment starts passing the exit surface of a communicating hole. The XVIII part enlarged view when the inner needle collar part of the injector by 2nd Embodiment passes the exit surface of a communicating hole. The XIX part enlarged view after the inner needle collar part of the injector by 2nd Embodiment passes the exit surface of a communicating hole. The XX part enlarged view which the housing collar part of the injector by 2nd Embodiment starts passage through the entrance surface of a communicating hole. The XXI part enlarged view when the housing collar part of the injector by 2nd Embodiment passes the entrance surface of a communicating hole. The XXII section enlarged view when the housing collar part of the injector by 2nd Embodiment passes the entrance surface of a communicating hole. The XXIII section enlarged view after the housing collar part of the injector by 2nd Embodiment passes the entrance surface of a communicating hole. The change figure of the channel area of the injector by 2nd Embodiment. The change figure of the channel area of the injector by 3rd Embodiment. The change figure of the fuel injection quantity of the injector by 3rd Embodiment. (A) The front end side enlarged view of the injector by other embodiment, (b) XXVIIb-XXVIIb sectional view taken on the line of Fig.27 (a). (A) The front end side enlarged view of the injector by other embodiment, (b) XXVIIIb-XXVIIIb sectional view taken on the line of Fig.28 (a). (A) The front end side enlarged view of the injector by other embodiment, (b) XXIXb-XXIXb sectional view taken on the line of Fig.29 (a). (A) Enlarged view of tip of injector according to other embodiment, (b) XXXb-XXXb cross-sectional view of FIG. 30 (a), (c) XXXc-XXXc cross-sectional view of FIG. 30 (a), (d) FIG. XXXd-XXXd sectional view taken on the line 30 (a). The front end side enlarged view of the injector by other embodiment. The front end side enlarged view of the injector by other embodiment. The front end side enlarged view of the injector by other embodiment.

A fuel injection device according to an embodiment of the present invention will be described with reference to the drawings. In the description of the plurality of embodiments, the same reference numerals are given to the substantially same configurations as those in the first embodiment. This fuel injection device has an outer needle and an inner needle accommodated coaxially in a housing, and performs fuel injection control by adjusting the lift amount of the outer needle and the inner needle.
(First embodiment)

  The fuel injection device according to the first embodiment of the present invention (hereinafter referred to as “injector”) will be described with reference to FIGS. The configuration will be described with reference to FIGS. A broken line is abbreviate | omitted with respect to sectional drawing of a figure.

The injector 1 of this embodiment is attached to each cylinder of a diesel engine, and injects fuel stored in a common rail 8 in a high pressure state into each cylinder.
As shown in FIG. 1, the injector 1 includes a housing 10, an outer needle 38, an inner needle 37, and a drive unit 90.

The housing 10 is formed in a bottomed cylindrical shape by a metal material such as carbon steel, for example. The housing 10 has fuel passages 17, 23, 24, 25, 251, a first back pressure chamber 21 and a second back pressure chamber 22 on the rear end side.
Further, the housing 10 has a nozzle chamber 11, a valve seat 13, a first injection hole 121, a second injection hole 122, and a housing flange 101 on the tip side.

  The fuel passage 24 communicates with the fuel passage 17, the fuel passage 25, and the fuel passage 251. The fuel passage 23 and the fuel passage 25 are communicated with the first back pressure chamber 21. The fuel passage 251 communicates with the second back pressure chamber 22.

The nozzle chamber 11 communicates with the fuel passage 17. The valve seat 13 is formed on the conical inner wall surface at the bottom.
The first injection hole 121 is formed on the tip side of the second injection hole 122, that is, on the axial center side of the housing 10. A plurality of first nozzle holes 121 and second nozzle holes 122 are formed at predetermined intervals in the circumferential direction of the housing 10.

  As shown in FIG. 2, the housing flange 101 expands in the radially inward direction and protrudes from the inner side surface 102 of the housing 10. It contacts an outer surface 392 of an outer needle 38 to be described later. Further, the housing flange 101 is disposed on the rear end side of the communication hole 381 of the outer needle 38 when the outer needle 38 is closed. Further, the housing flange 101 passes through the inlet surface 382 of the communication hole 381 when the outer needle 38 slides.

The outer needle 38 is formed in a cylindrical shape, and is accommodated in the housing so as to be slidable in the axial direction. It slides with the sliding contact portion 15 of the housing 10 with a predetermined clearance.
The outer needle 38 has an outer needle spring 93 on the rear end side. The outer needle 38 has a seat portion 19, a protruding portion 389, and a communication hole 381 on the distal end side.

The outer needle spring 93 abuts on the housing 98 and the head 98 which is the rear end side of the outer needle 38 in the second back pressure chamber 22 to urge the outer needle 38 toward the front end side.
The seat portion 19 is formed at the end portion on the distal end side of the outer needle 38. The seat part 19 opens and closes the second injection hole 122 by being separated and seated on the valve seat 13 by the outer needle 38.
The protruding portion 389 is disposed on the rear end side of the communication hole 381, expands in the radial inner direction of the outer needle 38, and protrudes from the inner side surface 391 of the outer needle 38.

  As shown in FIGS. 2 and 3, the communication hole 381 includes an inlet surface 382 disposed on the outer surface 392 of the outer needle 38 and an outlet surface 384 disposed on the inner surface 391 of the outer needle 38. And the exit surface 384 are communicated. Further, the same number of four communication holes 381 as the housing flange 101 are formed at equal intervals.

  Furthermore, the communication hole 381 is formed so as to be disposed on the front end side of the housing flange 101 when the outer needle 38 is closed. The hole diameter of the communication hole is constant and the cross section in the radial direction is rectangular. Any method may be used for machining the communication hole, such as machining with a tool such as a drill or electric discharge machining.

  The inner needle 37 is formed in a cylindrical shape, and is accommodated in a radially inward direction of the outer needle 38 so as to reciprocate in the axial direction coaxially with the outer needle 38. The inner needle 37 is in fluid-tight sliding contact with the inner wall of the outer needle 38 in the radial direction, and regulates the flow of fuel in the first back pressure chamber 21. The outer surface 378 of the inner needle 37 is recessed from a part on the rear end side to the front end side with respect to the communication hole 381.

The inner needle 37 has an inner needle spring 92 on the rear end side. The inner needle 37 has a seat portion 18 and an inner needle collar portion 371 on the distal end side.
The inner needle spring 92 abuts against the head portion 97 that is the end portion on the rear end side of the inner needle 37 and the housing 10 in the first back pressure chamber 21 to urge the inner needle 37 toward the front end side.
The seat portion 18 is formed at the end portion on the distal end side of the inner needle 37. The seat part 18 opens and closes the first injection hole 121 by being separated and seated on the valve seat 13 by the inner needle 37.

  As shown in FIG. 3, like the housing collar 101, the inner needle collar 371 is formed in the same number as the communication hole, expands radially outward, and projects from the outer surface 378. The inner needle collar 371 contacts the inner side surface 391 of the outer needle 38.

The inner needle collar portion 371 closes the outlet surface 384 of the communication hole 381 when the inner needle 37 is closed.
Further, when the inner needle 37 slides, the inner needle collar 371 abuts the upper end surface 376 of the inner needle collar 371 and the lower end surface 386 of the protruding portion 389 of the outer needle 38. Furthermore, the inner needle collar 371 passes through the outlet surface 384 of the communication hole 381 when the inner needle 37 slides.

  The drive unit 90 opens and closes the fuel passage 23 of the first back pressure chamber 21 and includes an electronic control unit (ECU). It is configured by a solenoid coil that is energized by an ECU command to generate a magnetic attractive force and displaces the fuel passage 23 in the opening direction.

Next, the operation of the injector 1 of the first embodiment will be described.
High pressure fuel is supplied from the common rail 8 to the nozzle chamber 11 of the housing 10 via the fuel passages 24 and 17. The high-pressure fuel in the nozzle chamber 11 is supplied through the communication hole 381 of the outer needle 38. The supplied fuel acts on the pressure receiving surface 372 of the first brim portion 371 of the inner needle 37 and urges the inner needle 37 in the valve opening direction. Here, a pressure receiving surface may be provided separately. For example, a fuel passage hole that penetrates the outer needle 38 is provided on the rear end side of the housing flange 101. The high-pressure fuel in the nozzle chamber 11 is supplied through the fuel passage hole, and the supplied fuel acts on the recessed surface of the inner needle as a pressure receiving surface.

  The first back pressure chamber 21 is supplied with high-pressure fuel having the same pressure as that of the nozzle chamber 11 from the common rail 8 via the fuel passage 25. The high-pressure fuel in the first back pressure chamber 21 acts on the head 97 of the inner needle 37 and urges the inner needle 37 in the valve closing direction.

  The biasing force that the fuel pressure in the first back pressure chamber 21 acts on the head 97 is F1, and the biasing force of the inner needle spring 92 is Fs1. In addition, Fi is a biasing force that the fuel pressure in the nozzle chamber 11 acts on the pressure receiving surface 372. The urging forces F1 and Fs1 are forces that urge the inner needle 37 in the valve closing direction, and the urging forces Fi are forces that urge the inner needle 37 in the valve opening direction.

When the solenoid coil of the drive unit 90 is not energized, that is, when the valve body is displaced in the closing direction, the following relational expression (1) is satisfied.
F1 + Fs1> Fi (1)
Therefore, the seat portion 18 of the inner needle 37 is seated on the valve seat 13 and closes the first injection hole 121.

  The urging force at which the fuel pressure in the second back pressure chamber 22 acts on the head 98 is F2, and the urging force of the outer needle spring 93 is Fs2. The urging forces F2 and Fs2 are forces that urge the outer needle 38 in the valve closing direction. The outer needle 38 is urged by the urging forces F2 and Fs2. For this reason, the seat part 19 of the outer needle 38 is seated on the valve seat 13 and closes the second injection hole 122.

In response to an instruction from the ECU, when the solenoid coil of the drive unit 90 is energized, the fuel flows out from the first back pressure chamber 21 and the fuel pressure in the first back pressure chamber 21 decreases. At this time, the following relational expression (2) is satisfied.
F1 + Fs1 <Fi (2)
For this reason, the inner needle 37 slides in the valve opening direction. When the seat portion 18 of the inner needle 37 is separated from the valve seat 13, the nozzle chamber 11 and the first injection hole 121 communicate with each other, and fuel is injected from the first injection hole 121.

When the solenoid coil is continuously energized, the upper end surface 376 of the first collar 371 of the inner needle 37 and the lower end surface 386 of the protruding portion 389 of the outer needle 38 come into contact with each other. The inner needle 37 and the outer needle 38 come into contact with each other, and the biasing force that the inner needle 37 acts on the outer needle 38 is defined as Fio. The urging force Fio is a force that urges the outer needle 38 in the valve opening direction. At this time, the following relational expression (3) is satisfied.
F2 + Fs2 <Fio (3)
For this reason, the outer needle 38 slides in the valve opening direction together with the inner needle 37. When the seat portion 19 of the outer needle 38 is separated from the valve seat 13, fuel is injected from the first injection hole 121 and the second injection hole 122.

  When energization of the solenoid coil is stopped by a command from the ECU, fuel flows into the first back pressure chamber 21 via the fuel passage 25, and the fuel pressure in the first back pressure chamber 21 increases. Thereby, the relational expression (1) is also satisfied. For this reason, the inner needle 37 slides in the valve closing direction. At this time, since the urging force Fo becomes zero, the outer needle 38 also slides in the valve closing direction by the urging forces F2 and Fs2, that is, the inner needle 37 and the outer needle 38 both slide in the valve closing direction. . When the seat portion 18 of the inner needle 37 is seated on the valve seat 13, the fuel injection through the first injection hole 121 is stopped. Similarly, when the seat portion 19 of the outer needle 38 is seated on the valve seat 13, fuel injection through the second injection hole 122 is stopped.

  Next, the flow path constituted by the housing 10, the outer needle 38, and the inner needle 37 will be described. The configured channels are the first channel 27, the second channel 28, the third channel 29, the inlet hole channel 383, and the outlet hole channel 385.

  As shown in FIG. 4, the first flow path 27 is a flow path formed between the outer surface 378 of the inner needle 37 and the inner surface 391 of the outer needle 38. The channel area of the first channel is A1. The channel area A1 is the area of the side surface of the truncated cone having the shortest distance α between the outer surface 378 of the inner needle 37 and the inner surface 391 of the outer needle 38 as a hypotenuse.

  As shown in FIG. 5, the second flow path 28 is a flow path formed between the inner surface 102 of the housing 10. The channel area of the second channel 28 is A2. The flow path area A2 is the area of the side surface of the truncated cone having the shortest distance β between the outer peripheral surface 392 of the outer needle 38, the inner peripheral surface 102 of the housing 10 and the outer peripheral surface 392 of the outer needle 38 as a hypotenuse.

  The third channel 29 is a channel formed between the outer surface 378 of the inner needle 37 and the inner surface 102 of the housing 10. The channel area of the third channel is A3. The flow path area A3 is the area of the side surface of the truncated cone having the shortest distance γ between the outer surface 378 of the inner needle 37 and the inner surface 102 of the housing 10 as a hypotenuse.

  The inlet hole channel 383 is a channel formed by the housing flange 101 and the inlet surface 382 of the communication hole 381. Let Ai be the channel area of the inlet hole channel 383. The flow path area Ai is maximum when the outer needle 38 is closed. When the outer needle 38 is closed, the housing flange 101 is located on the rear end side of the communication hole 381 and does not block the inlet surface 382 of the communication hole 381.

  The outlet hole channel 385 is a channel formed by the inner needle flange 371 and the outlet surface 384 of the communication hole 381. A channel area of the outlet hole channel 385 is defined as Ao. Further, the flow path area Ao when the inner needle valve 37 is closed is Ao0. The first flow path 27 communicates with the outlet hole flow path 385, that is, the flow path area Ao0> 0.

  4 and 5, the high-pressure fuel supplied from the nozzle chamber 11 passes through the outlet hole channel 385 and the first channel 27 when the inner needle 37 slides in the valve opening direction. Then, it is injected from the first nozzle hole 121. As indicated by a dashed line, the high-pressure fuel is injected from the second injection hole 122 via the second flow path 28 when the outer needle 38 slides in the valve opening direction.

  The change rate with respect to time of the flow passage area A1 when the inner needle 37 slides in the valve opening direction is ΔA1, and the change rate with respect to time of the flow passage area A2 when the outer needle 38 slides in the valve opening direction is ΔA2. And Further, a change rate with respect to time of the flow passage area A3 when the inner needle 37 slides in the valve opening direction is denoted by ΔA3.

  Further, the change rate of the flow passage area Ai with respect to time when the housing flange 101 passes through the inlet surface 382 of the communication hole 381 is represented by ΔAi. Let ΔAo be the rate of change of the channel area Ao with respect to time when the inner needle collar 371 passes through the outlet surface 384 of the communication hole 381. Here, the change rate may be a change rate of the flow path area with respect to the sliding amount of the inner needle 37 and the outer needle 38, that is, the lift amount.

The diameters of the housing 10, the housing collar 101, the inner needle 37, the inner needle collar 371, the outer needle 38, and the communication hole 381 are set so that the following relational expressions (4.1) to (4.3) are satisfied: Is set.
Ao0> 0 (4.1)
ΔA1> ΔAo (4.2)
ΔA2> | ΔAi | (4.3)
Since the change rate ΔAi has a negative value, the absolute value is used for the relational expression (4.3). The housing flange 101 is for closing and opening the inlet hole channel 383 when the outer needle 38 slides.

The channel area of the first nozzle hole 121 is Ah1, and the channel area of the second nozzle hole 122 is Ah2. The maximum value of the channel area Ao is set to Max (Ao). Further, the maximum value of the flow path area A2 is set to Max (A2), and the diameter of the first injection hole 121 and the second injection hole 122 are satisfied so that the following relational expressions (5.1) and (5.2) are satisfied. The diameter of is set.
Max (Ao) ≧ Ah1> Ao0 (5.1)
Max (A2) ≧ Ah2 (5.2)

Next, the fuel injection amount of the injector 1 according to the first embodiment will be described.
From the orifice equation according to Bernoulli's law, the fuel injection amount is expressed by the following relational expression (6).
Q = C × Amin × √ (2ΔP / ρ) (6)
Here, Q is the fuel injection amount, C is the flow coefficient, Amin is the minimum flow path area, ΔP is the pressure difference, and ρ is the density. The flow coefficient C is a constant resulting from the structure and is a constant. The pressure difference ΔP is a constant because the supplied fuel pressure is constant. The fuel is incompressible and the density ρ is also a constant. Therefore, the fuel injection amount is determined by the minimum flow path area Amin of the path through which the fuel is injected. Hereinafter, the fuel injection amount will be described using the minimum flow path area Amin.

  The minimum flow path area Amin1 of the path through which the fuel is injected from the first injection hole 121 via the first flow path 27 is set. In the first embodiment, the third channel 29 is not used because the channel area A3 is large. Further, the minimum flow path area of the path through which the fuel is injected from the second injection hole 122 via the second flow path 28 is Amin2. The minimum flow path area Amin related to the fuel injection amount of the first embodiment is the sum of Amin1 and Amin2.

  In the present embodiment, the inner needle 37 has an inner needle collar 371 that protrudes outward in the radial inner direction on the outer surface of the inner needle 37. The housing 10 also has a housing flange 101 that protrudes inward in the radial direction on the inner surface of the housing 10. Further, the outer needle 38 has at least one communication hole 381.

  The inner needle collar 371 is formed so as to pass through the outlet surface 384 of the communication hole 381 of the outer needle 38 when the inner needle 37 slides in the valve opening direction. The housing flange 101 is formed so as to pass through the inlet surface 381 of the communication hole 381 of the outer needle valve 38 when the outer needle 38 slides in the valve opening direction. Thereby, the flow path area of the flow path to which fuel is supplied can be changed, and the fuel injection amount can be controlled with high accuracy.

  The action of the inner needle collar 371, the housing collar 101, and the communication hole 381 of the outer needle 38 of the first embodiment changing the flow path area will be described with reference to FIGS.

  As shown in FIG. 6, when the solenoid coil is not energized, the inner needle collar 371 overlaps the outlet surface 385 of the communication hole 381. The outlet hole channel 385 is opened and communicates with the first channel 27, that is, Ao0> 0. The flow path area Ao is smaller than the flow path area Ai, that is, Ai> Ao. Since the inner needle 37 and the outer needle 38 are closed, the flow path area A1 is zero and the flow path area A2 is zero. Therefore, the minimum flow path area Amin1 at this time is zero, and the minimum flow path area Amin2 is zero.

As shown in FIG. 7, when the solenoid coil is energized according to a command from the ECU, the inner needle 37 slides in the valve opening direction. The inner needle 37 opens the first flow path 27, and the inner needle collar 371 opens the outlet hole flow path 385. From the relational expression (4.1), the following relational expressions (7.1) to (7.4) are satisfied at this time.
Ao> A1 (7.1)
Amin1 = A1 (7.2)
Amin2 = 0 (7.3)
Amin = A1 (7.4)
Accordingly, the fuel injection amount at this time is determined by the flow path area A1.

  As the inner needle 37 slides in the valve opening direction, the first flow path 27 is opened, the distance α increases, and the flow path area A1 increases. In addition, since the inner needle collar 371 opens the outlet hole channel 385, the channel area Ao increases.

As shown in FIG. 8, when the inner needle collar 371 passes through the outlet surface 384 of the communication hole 381, the following relational expressions (8.1) to (8.4) are obtained from the relational expression (4.2). It is filled.
A1> Ao (8.1)
Amin1 = Ao (8.2)
Amin2 = 0 (8.3)
Amin = Ao (8.4)
Accordingly, the fuel injection amount at this time is determined by the flow path area Ao.

As shown in FIG. 9, the inner needle collar 371 opens the closed outlet hole channel 385, and the channel area Ao is the maximum, that is, the channel area Ao at this time is Max (Ao). It is. The channel area Ao is equal to the channel area Ai, that is, Ao = Ai. From the relational expression (5.1), the following relational expressions (9.1) to (9.3) are satisfied.
Amin1 = Ah1 (9.1)
Amin2 = 0 (9.2)
Amin = Ah1 (9.3)
Accordingly, the fuel injection amount at this time is determined by the flow path area Ah1.
Furthermore, when the inner needle 37 slides in the valve opening direction, the upper end surface 376 of the inner needle collar 371 and the lower end surface 386 of the protruding portion 389 of the outer needle 38 abut. That is, both the inner needle 37 and the outer needle 38 slide in the valve opening direction.

As shown in FIG. 10, the outer needle 38 opens the second flow path 28, and the housing flange 101 closes the inlet hole flow path 383. At this time, the following relational expressions (10.1) to (10.4) are satisfied.
Ao> Ai (10.1)
Amin1 = Ai (10.2)
Amin2 = A2 (10.3)
Amin = Ai + A2 (10.4)
Accordingly, the fuel injection amount at this time is determined by the sum of the flow passage areas Ai and A2.
As the outer needle 38 slides, the second flow path 28 is opened, the distance β increases, and the flow path area A2 increases.

As shown in FIG. 11, when the end surface of the housing flange 101 is included in the inlet surface 382 of the communication hole 381, the area of the inlet hole channel 383 does not change. Therefore, the change rate ΔAi is zero, and the flow path area Ai is constant. The flow path area at this time satisfies the following relational expressions (11.1) to (11.4) similarly to the relational expressions (10.1) to (10.4).
Ao> Ai (11.1)
Amin1 = Ai (11.2)
Amin2 = A2 (11.3)
Amin = Ai + A2 (11.4)
Accordingly, the fuel injection amount at this time is determined by the sum of the flow passage areas Ai and A2.
Further, when the housing collar 101 passes through the inlet surface 382, the housing collar 101 opens the inlet hole channel 385. At this time, the change rate ΔAi becomes a positive value, and the flow path area Ai increases.

As shown in FIG. 12, the housing flange 101 fully opens the inlet hole channel 383. From the relational expressions (5.1) and (5.2), the following relational expressions (12.1) to (12.4) are satisfied.
Ao = Ai (12.1)
Amin1 = Ah1 (12.2)
Amin2 = Ah2 (12.3)
Amin = Ah1 + Ah2 (12.4)
Therefore, the fuel injection amount at this time is determined by the sum of the flow path areas Ah1 and Ah2.

  With reference to FIG. 13, the change of the minimum flow path areas Amin1 and Amin2 with respect to time in the first embodiment will be described. Here, the rate of change of the minimum channel area Amin1 with respect to time is ΔAmin1, and the rate of change of the minimum channel area Amin2 with respect to time is ΔAmin2.

Times T0 to T1 correspond to FIG. 6 and FIG. 7, and are the time for the inner needle collar 371 to pass through the outlet surface 384 from the start of passage. Time T0 is a time during which the solenoid coil is energized in accordance with a command from the ECU. Time T1 is when the channel area A1 becomes equal to the channel area Ao. From the relational expressions (7.2) and (7.3), the change rates ΔAmin1 and ΔAmin2 from the time T0 to the time T1 are expressed by the following expressions (7.5) and (7.6).
ΔAmin1 = ΔA1 (7.5)
ΔAmin2 = 0 (7.6)

Similarly, times T1 to T2 are times corresponding to FIG. From the relational expressions (8.2) and (8.3), the change rates ΔAmin1 and ΔAmin2 from the time T1 to the time T2 are expressed by the following expressions (8.5) and (8.6).
ΔAmin1 = ΔAo (8.5)
ΔAmin2 = 0 (8.6)
From the relational expression (5.2), the change rate ΔAmin1, that is, the slope of the minimum flow path area Amin1 decreases from the time T1. Time T2 is the time for the inner needle collar 371 to fully open the outlet hole channel 385.

Times T2 to T3 are times corresponding to FIG. From the relational expressions (9.1) and (9.2), the change rates ΔAmin1 and ΔAmin2 from the time T2 to the time T3 are expressed by the following expressions (9.4) and (9.5).
ΔAmin1 = 0 (9.4)
ΔAmin2 = 0 (9.5)
The change rate ΔAmin1 from time T2 to T3 is zero because the minimum flow path area Amin1 is the flow path area Ah1. Further, the rate of change ΔAmin2 from time T0 to T3 is zero because the outer needle valve is closed.
Time T3 is a time when the upper end surface 376 of the inner needle collar 371 and the lower end surface 386 of the protruding portion 389 of the outer needle 38 abut.

Times T3 to T4 are times corresponding to FIG. From the relational expressions (10.2) and (10.3), the change rates ΔAmin1 and ΔAmin2 from time T3 to T4 are expressed by the following expressions (10.5) and (10.6).
ΔAmin1 = ΔAi (10.5)
ΔAmin2 = ΔA2 (10.6)

From time T3 to T4, the housing flange 101 closes the inlet hole channel 383, so that the change rate ΔAi has a negative value. For this reason, the minimum flow path area Amin1 decreases. From the relational expression (4.3), the sum of the change rates ΔAmin1 and ΔAmin2 increases. Accordingly, the fuel injection amount also increases from time T3 to T4.
Time T4 is a time during which the end surface of the housing flange 101 is included in the inlet surface 382 of the communication hole 381.

Times T4 to T5 are times corresponding to FIG. From the relational expressions (11.2) and (11.3), the change rates ΔAmin1 and ΔAmin2 from time T4 to T5 are expressed by the following relational expressions (11.5) and (11.6).
ΔAmin1 = 0 (11.5)
ΔAmin2 = ΔA2 (11.6)
The time T5 is the time when the flow path area A2 exceeds the flow path area Ah2, and the time when the housing flange 101 opens the inlet hole flow path 383.

Times T5 to T6 are times corresponding to FIG. From the relational expressions (12.2) and (12.3), the change rates ΔAmin1 and ΔAmin2 from time T5 to T6 are expressed by the following relational expressions (12.5) and (12.6).
ΔAmin1 = ΔAi (12.5)
ΔAmin2 = 0 (12.6)
Time T6 is the time when the housing flange 101 opens the inlet hole channel 383. Therefore, from time T6 to T7, the minimum flow path area Amin1 is the flow path area Ah1, and the minimum flow path area Amin2 is the flow path area Ah2. The change rates ΔAmin1 and ΔAmin2 from time T6 to T7 are both zero because the channel area Ah1 and the channel area Ah2 do not change.

As described above, the flow passage area can be changed by the inner needle flange 371, the housing flange 101, and the communication hole 381 of the outer needle 38. Therefore, the fuel injection amount can be changed according to the change of the flow path area.
(effect)

First, with reference to FIG. 14, the sabate cycle which has a constant pressure heating process is demonstrated.
The Sabate cycle consists of five steps: adiabatic compression process from S1 to S2, a constant volume heating process from S2 to S3, a constant pressure heating process from S3 to S4, adiabatic expansion process from S4 to S5, and a constant volume cooling process from S5 to S1. The process related to fuel injection is a constant pressure heating process from S3 to S4. In the constant pressure heating process, when the fuel is directly injected from the injector 1 into the compressed air of high pressure and high temperature, the fuel spontaneously ignites and burns, and this thermal energy is injected into the combustion chamber under a constant pressure.

  Referring to FIG. 15, as a comparative example, for example, the fuel injection amount with respect to time of a fuel injection device that does not have an inner needle collar part, a housing collar part, and a communication hole of an outer needle described in Patent Document 1 This relationship is indicated by a broken line. The fuel injection amount of the comparative example converges to a certain amount in two stages. This is because the flow path configuration is only a flow path corresponding to the first flow path, the second flow path, the first injection hole, and the second injection hole. Moreover, the minimum flow area of the first nozzle hole is determined for the fixed amount in the first stage. Furthermore, since the fixed amount in the second stage is determined by the minimum flow path area of the first nozzle hole and the minimum flow path area of the second nozzle hole, it converges to a certain amount in two stages.

  On the other hand, in this embodiment, it has the inner needle collar part 371, the housing collar part 101, and the communication hole 381 of an outer needle. The inner needle collar 371 and the housing collar 101 change the flow area of the inlet hole channel 383 and the outlet hole channel 385 of the communication hole 381 of the outer needle 38 by sliding between the inner needle 37 and the outer needle 38. To do. Thereby, a flow path structure increases and the controllability of a flow path area improves.

As shown in FIG. 15A, the fuel injection amount changes depending on the flow path area, and therefore, the fuel injection amount can be changed to increase continuously.
As shown in FIG. 15 (b), the pressure in the constant pressure heating process decreases in the Sabatate cycle of the comparative example, but in the present embodiment, the pressure in the constant pressure heating process becomes constant. In the comparative example, since the fuel injection amount is constant in the constant pressure heating process of the sabatate cycle, when the volume increases, the in-cylinder pressure cannot be maintained and the pressure decreases.

  In the present embodiment, combustion is promoted by continuously increasing the fuel injection amount. That is, as the explosion force increases continuously, the cylinder pressure can be maintained when the volume increases, and the pressure is kept constant. Therefore, the fuel injection amount can be made highly accurate, the pressure drop in the constant pressure heating process of the sabatate cycle can be suppressed, and a good combustion state can be achieved.

(Second Embodiment)
The injector 2 of 2nd Embodiment is demonstrated with reference to FIGS. In the second embodiment, the outer needle 38 opens prior to the inner needle 37 in the same configuration as in the first embodiment. Hereinafter, the change of the structure of the housing 10, the outer needle 38, the inner needle 37, and the drive part 90 is demonstrated.

The housing 10 further includes a fuel passage 231 instead of the sealing valve 105 and the fuel passage 23.
The sealing valve 105 is formed on the rear end side of the housing flange 101. Further, the high pressure fuel supplied from the nozzle chamber 11 is sealed in close contact with the outer surface 392 of the outer needle 38. For this reason, high-pressure fuel is not supplied to the nozzle chamber 11 on the tip side from the sealing valve 105.
The fuel passage 231 communicates with the second back pressure chamber 22 and is connected to the drive unit 90.

The outer needle 38 is recessed at the tip side from the fuel passage 17, and includes an inter-needle flow passage 26, a pressure receiving surface 393, and a fuel passage hole 394. Further, the arrangement of the protruding portion 389 of the outer needle 38 is changed.
The inter-needle channel 26 is a channel that is formed by the outer surface 378 of the inner needle 37 and the inner surface 391 of the outer needle 38 and is located on the rear end side of the communication hole 381. Further, the inter-needle channel 26 communicates with the second channel 28 via the outlet hole channel 385 and the inlet hole channel 383 when the outer needle 38 is closed.

The pressure receiving surface 393 is formed between the fuel passage 17 and the nozzle chamber 11, and is recessed so as to receive the pressure of the high-pressure fuel supplied from the common rail 8 through the fuel passage 17.
The fuel passage hole 394 is disposed on the rear end side of the sealing valve 105 and penetrates the inner surface 391 and the outer surface 392 of the outer needle 38. The fuel passage hole 394 supplies high-pressure fuel supplied from the common rail to the inter-needle passage 26 via the fuel passage 17 and the nozzle chamber 11.
The protruding portion 389 is disposed on the distal end side with respect to the communication hole 381. Further, when the outer needle 38 slides in the valve opening direction, the upper end surface 390 of the protruding portion 389 contacts the lower end surface 377 of the inner needle collar portion 37.

The inner needle 37 contacts the housing 10 when the inner needle 37 is closed, and has a third flow path. The third flow path is a flow path formed by the inner needle 37 and the housing 10.
The drive unit 90 is a valve body that opens and closes the fuel passage 231 of the second back pressure chamber 22, and is configured by a solenoid coil as in the first embodiment.

The operation of the second embodiment will be described.
The high pressure fuel supplied via the fuel passage 17 acts on the pressure receiving surface 393 of the outer needle 38. The high pressure fuel in the nozzle chamber 11 is supplied to the third flow path 29 via the fuel passage hole 394 of the outer needle 38 and the inter-needle flow path 26.

Let the fuel pressure be the urging force Fo acting on the pressure receiving surface 393 of the outer needle 38. The urging force Fo is a force that urges the outer needle 38 in the valve opening direction.
When the solenoid coil of the drive unit 90 is not energized, the following relational expression (13) is satisfied.
F2 + Fs2> Fo (13)
For this reason, the seat part 19 of the outer needle 38 is seated on the valve seat 13 and closes the second injection hole 122. In the second embodiment, the inner needle 37 has an urging force Fi of zero, and is urged by the urging forces F1 and Fs1. Therefore, the seat portion 18 of the inner needle 37 is seated on the valve seat 13 and closes the first injection hole 121.

According to a command from the ECU, when the solenoid coil of the drive unit 90 is energized, the fuel flows out from the second back pressure chamber 22 and the fuel pressure in the second back pressure chamber 22 decreases. At this time, the following relational expression (14) is satisfied.
F2 + Fs2 <Fo (14)
For this reason, the outer needle 38 slides in the valve opening direction. When the seat portion 19 of the outer needle 38 is separated from the valve seat 13, the inter-needle flow path 26, the second flow path 28, and the second injection hole 122 communicate with each other, and fuel is injected from the second injection hole 122.

When the solenoid coil is continuously energized, the upper end surface 390 of the protruding portion 389 of the outer needle 38 and the lower end surface 377 of the inner needle collar portion 371 of the inner needle 37 abut. The urging force that the outer needle 38 acts on the inner needle 37 is Foi. The urging force Foi is a force that urges the inner needle 37 in the valve opening direction. At this time, the following relational expression (15) is satisfied.
F1 + Fs1 <Foi (15)
For this reason, the inner needle 37 slides in the valve opening direction together with the outer needle 38. When the seat portion 18 of the inner needle 37 is separated from the valve seat 13, fuel is injected from the first injection hole 121 and the second injection hole 122.

  When the energization of the solenoid coil is stopped by an instruction from the ECU, fuel flows into the second back pressure chamber 22 via the fuel passage 251 and the fuel pressure in the second back pressure chamber rises. Thereby, the relational expression (13) is also satisfied. For this reason, as in the first embodiment, both the outer needle 38 and the inner needle slide in the valve closing direction, and fuel injection through the first injection hole 121 and the second injection hole 122 stops.

  The configuration of the flow path of the second embodiment will be described. The configuration of the flow path is the same as that of the first embodiment, and the first flow path 27 is replaced with the third flow path 29.

  As indicated by a broken line in FIG. 17, the high-pressure fuel supplied from the nozzle chamber 11 flows between the needle passage 26, the outlet hole passage 385, and the second passage 28 when the outer needle 38 slides in the valve opening direction. And is ejected from the second nozzle hole 122. As indicated by a dashed line, the high-pressure fuel is injected from the first injection hole 121 via the inter-needle passage 26 and the third passage 29 when the inner needle 37 slides in the valve opening direction. The

The diameters of the housing 10, the housing collar 101, the inner needle 37, the inner needle collar 371, the outer needle 38, and the communication hole 381 so that the relational expression (4.1) and the following relational expression (16.1) are satisfied. Is set.
ΔA2> ΔAo (16.1)
ΔA3> | ΔAi | (16.2)
Similar to the first embodiment, an absolute value is used.

Furthermore, the diameter of the first injection hole 121 and the diameter of the second injection hole 122 are set so that the following relational expressions (17.1) and (17.2) are satisfied.
Max (Ao) ≧ Ah2> Ao0 (17.1)
Max (A3) ≧ Ah1 (17.2)

  Let Amin3 be the minimum flow path area of the path through which the fuel is injected from the first injection hole 121 via the third path 29. The minimum flow path area Amin related to the fuel injection amount of the second embodiment is the sum of Amin2 and Amin3.

  The action of the inner needle collar 371, the housing collar 101, and the communication hole 381 of the outer needle 38 of the second embodiment changing the flow path area will be described with reference to FIGS.

  As shown in FIG. 17, when the solenoid coil is not energized, the inner needle collar 371 overlaps with the outlet surface 385 of the communication hole 381 as in the first embodiment. The outlet hole channel 385 is opened and communicates with the second channel 28. The flow path area Ao is smaller than the flow path area Ai, that is, Ai> Ao.

As shown in FIG. 18, when the solenoid coil is energized in accordance with a command from the ECU, the outer needle 38 slides in the valve opening direction. The outer needle 38 opens the second flow path 28, and the inner needle collar 371 opens the outlet hole flow path 385. From the relational expression (4.1), the following relational expressions (18.1) to (18.4) are satisfied at this time.
Ao> A2 (18.1)
Amin2 = A2 (18.2)
Amin3 = 0 (18.3)
Amin = A2 (18.4)
Accordingly, the fuel injection amount at this time is determined by the flow path area A2.

  As the outer needle 38 slides in the valve opening direction, the second flow path 28 is opened, the distance β increases, and the flow path area A2 increases. In addition, since the inner needle collar 371 opens the outlet hole channel 385, the channel area Ao increases.

As shown in FIG. 19, when the inner needle collar 371 passes through the outlet surface 384 of the communication hole 381, the following relational expressions (19.1) to (19.4) are obtained from the relational expression (16.1). It is filled.
A2> Ao (19.1)
Amin2 = Ao (19.2)
Amin3 = 0 (19.3)
Amin = Ao (19.4)
Therefore, the fuel injection amount at this time is determined by Ao.

As shown in FIG. 20, the inner needle collar 371 opens the closed outlet hole channel 385, and the channel area Ao is maximized. From the relational expression (16.1), the following relational expressions (20.1) to (20.3) are satisfied.
Amin2 = Ah2 (20.1)
Amin3 = 0 (20.2)
Amin = Ah2 (20.3)
Therefore, the fuel injection amount at this time is determined by Ah2.
Further, when the outer needle 38 slides in the valve opening direction, the upper end surface 390 of the protruding portion 389 of the outer needle 38 and the lower end surface 377 of the inner needle collar 371 contact each other. That is, both the outer needle 38 and the inner needle 37 slide in the valve opening direction.

As shown in FIG. 21, the inner needle 27 opens the third flow path 29, and the housing flange 101 closes the inlet hole flow path 383. At this time, the following relational expressions (21.1) to (21.4) are satisfied.
Ao> Ai (21.1)
Amin2 = Ai (21.2)
Amin3 = A3 (21.3)
Amin = Ai + A3 (21.4)
Accordingly, the fuel injection amount at this time is determined by the sum of the flow passage areas Ai and A3.
Further, as the inner needle 37 slides, the third flow path 29 is opened, the distance γ increases, and the flow path area A3 increases.

As shown in FIG. 22, when the end surface of the housing flange 101 is included in the inlet surface 382 of the communication hole 381, the area of the inlet hole channel 383 does not change. Therefore, the change rate ΔAi is zero, and the flow path area Ai is constant. The flow path area at this time satisfies the relational expressions (22.1) to (22.4) as in the relational expressions (21.1) to (21.4).
Ao> Ai (22.1)
Amin2 = Ai (22.2)
Amin3 = A3 (22.3)
Amin = Ai + A3 (22.4)
Accordingly, the fuel injection amount at this time is determined by the sum of the flow passage areas Ai and A3.

As shown in FIG. 23, the housing flange 101 fully opens the inlet hole channel 383. From the relational expressions (17.1) and (17.2), the following relational expressions (23.1) to (23.4) are satisfied.
Ao = Ai (23.1)
Amin2 = Ah2 (23.2)
Amin3 = Ah1 (23.3)
Amin = Ah2 + Ah1 (23.4)
Accordingly, the fuel injection amount at this time is determined by the sum of the flow path areas Ah2 and Ah1.

  With reference to FIG. 24, the change of the minimum flow path areas Amin2 and Amin3 with respect to time in the second embodiment will be described. Here, the change rate with respect to time of the minimum flow path area Amin3 is set to ΔAmin3.

Times T0 to T1 correspond to FIGS. 17 and 18, and are times when the inner needle collar 371 passes through the outlet surface 384 from the start of passage. Time T0 is a time during which the solenoid coil is energized in accordance with a command from the ECU. Time T1 is when the channel area A2 becomes equal to the channel area Ao. From the relational expressions (18.2) and (18.3), the change rates ΔAmin2 and ΔAmin3 from the time T0 to the time T1 are expressed by the following expressions (18.5) and (18.6).
ΔAmin2 = ΔA2 (18.5)
ΔAmin3 = 0 (18.6)

Similarly, times T1 to T2 are times corresponding to FIG. From the relational expressions (19.2) and (19.3), the change rates ΔAmin2 and ΔAmin3 from the time T1 to the time T2 are expressed by the following expressions (19.5) and (19.6).
ΔAmin2 = ΔAo (19.5)
ΔAmin3 = 0 (19.6)
From the relational expression (16.1), the change rate ΔAmin2, that is, the slope of the minimum flow path area Amin2 decreases from the time T1. The time T2 is the same as that in the first embodiment.

Times T2 to T3 are times corresponding to FIG. From the relational expressions (20.1) and (20.2), the change rates ΔAmin2 and ΔAmin3 from the time T2 to the time T3 are expressed by the following expressions (20.4) and (20.5).
ΔAmin2 = 0 (20.4)
ΔAmin3 = 0 (20.5)
The rate of change ΔAmin2 from time T2 to T3 is zero because the minimum flow path area Amin2 is the flow path area Ah2. Further, the rate of change ΔAmin3 from time T0 to T3 is zero because the inner needle 37 is closed.
The time T3 is a time when the upper end surface 390 of the protruding portion 389 of the outer needle 38 and the lower end surface 377 of the inner needle collar portion 371 come into contact with each other.

Times T3 to T4 are times corresponding to FIG. From the relational expressions (21.2) and (21.3), the change rates ΔAmin2 and ΔAmin3 from time T3 to T4 are expressed by the following relational expressions (21.5) and (21.6).
ΔAmin2 = ΔAi (21.5)
ΔAmin3 = ΔA3 (21.6)
From time T3 to T4, the housing flange 101 closes the inlet hole flow path 383 as in the first embodiment. From the relational expression (16.2), the sum of the change rates ΔAmin2 and ΔAmin3 of the minimum flow path area increases. Therefore, the fuel injection amount increases from time T3 to T4 as in the first embodiment.
Time T4 is a time during which the end surface of the housing flange 101 is included in the inlet surface 382 of the communication hole 381.

Times T4 to T5 are times corresponding to FIG. From the relational expressions (22.2) and (22.3), the change rates ΔAmin2 and ΔAmin3 from the time T4 to the time T5 are expressed by the following relational expressions (22.5) and (22.6).
ΔAmin2 = 0 (22.5)
ΔAmin3 = ΔA3 (22.6)
Time T5 is the time when the flow path area A3 exceeds the flow path area Ah1, and the housing flange 101 opens the inlet hole flow path 383.

Times T5 to T6 are times corresponding to FIG. From the relational expressions (23.2) and (23.3), the change rates ΔAmin2 and ΔAmin3 from time T5 to T6 are expressed by the following relational expressions (23.5) and (23.6).
ΔAmin2 = ΔA2 (23.5)
ΔAmin3 = 0 (23.6)
Time T6 is the time when the housing flange 101 opens the inlet hole channel 383. Therefore, from time T6 to T7, the minimum flow path area Amin2 is the flow path area Ah2, and the minimum flow path area Amin3 is the flow path area Ah1. The change rates ΔAmin2 and ΔAmin3 from time T6 to T7 are both zero because the channel area Ah1 and the channel area Ah2 do not change.
(effect)

  As described above, in the second embodiment, the flow passage area can be changed similarly to the first embodiment, and the fuel injection amount can be changed in accordance with the change in the flow passage area. Therefore, even in the form in which the outer needle 38 is opened prior to the inner needle 37, the fuel injection amount can be continuously increased, and the same effect as in the first embodiment can be obtained.

(Third embodiment)
The injector 3 according to the third embodiment will be described with reference to FIGS. 25 and 26. The injector 3 has the same configuration as that of the first embodiment, and the drive unit 90 has a speed variable mechanism that makes the sliding speed of the inner needle 37 and the outer needle 38 variable. The speed variable mechanism includes, for example, a piezoelectric actuator that is a piezoelectric element, and a pressure adjustment chamber whose volume changes due to expansion and contraction of the piezoelectric actuator.

The operation of the injector 3 of the third embodiment will be described.
The piezo actuator expands when the ECU applies the voltage Vs. When the piezoelectric actuator is extended, the volume of the pressure adjusting chamber is reduced and the fuel pressure in the first back pressure chamber 21 is increased. The voltage Vs is adjusted so that the relational expression (1) is satisfied, and the inner needle 37 is closed.

The ECU drops the voltage and the piezo actuator contracts. At this time, the volume of the pressure adjustment chamber is expanded, and the fuel pressure in the first back pressure chamber 21 is reduced. Accordingly, as in the first embodiment, since the relational expression (2) is satisfied, the inner needle 37 slides in the valve opening direction.
Further, when the ECU drops the voltage and contracts the piezo actuator, the outer needle 38 slides in the valve opening direction together with the inner needle 37.

  The ECU boosts the voltage to the voltage Vs, the piezo actuator expands, and the fuel pressure in the first back pressure chamber 21 similarly increases. Thereby, since the relational expression (1) is satisfied, the inner needle 37 and the outer needle 38 slide in the valve closing direction. Thereby, the fuel injection of the 1st nozzle hole 121 and the 2nd nozzle hole 122 stops.

  The ECU controls the voltage applied to the piezo actuator. By changing the voltage step-down speed, the fuel pressure in the first back pressure chamber 21 can be precisely controlled. Therefore, the sliding speed of the inner needle 37 in the valve opening direction can be changed, that is, the sliding speed of the inner needle 37 and the outer needle 38 can be made variable. Thereby, the change of the flow path area by the inner needle collar part 371 and the housing collar part 101 can be made precise, and the fuel injection amount can be controlled with higher accuracy.

By changing the sliding speed of the inner needle 37, the change rates ΔA1, ΔAo, ΔA2, and ΔAi can be changed. Further, the time T2 when the inner needle collar 371 fully opens the outlet hole channel 385 and the time T3 when the upper end surface 376 of the inner needle collar 371 and the lower end surface 386 of the protrusion 389 of the outer needle 38 abut are adjusted. be able to. For example, the sliding speed is adjusted so that the following relational expressions (24.1) to (24.3) are satisfied.
ΔAo = | ΔAi | (24.1)
ΔA2 = 2 | ΔAi | (24.2)
T2 = T3 (24.3)
Since the change rate ΔAi has a negative value, an absolute value is used.

With reference to FIG. 25, the change rates ΔAmin1 and ΔAmin2 according to the third embodiment will be described.
The change rates ΔAmin1 and ΔAmin2 from time T0 to T7 are the same as in the first embodiment, but in the third embodiment, the change rate ΔAmin1 from time T1 to T5 and the change rate Amin2 from time T3 to T5 change.

The change rate ΔAmin1 from the time T1 to the time T3 can be expressed by ΔAi from the relational expression (24.1). Further, from time T2 to T3, the change rate Amin1 can be prevented from becoming zero according to the relational expression (24.3). Further, the sliding speed is adjusted so that the end surface of the housing flange 101 is not included in the inlet surface 382 of the communication hole 381 from time T4 to T5.
The change rate ΔAmin2 from time T3 to T5 can be expressed by the change rate ΔAi. Further, it can be adjusted from time T4 to T5 so that the time when the housing flange 101 opens the inlet hole channel 383 coincides with the time when the channel area A2 exceeds the channel area Ah2.

  Thus, in the third embodiment, the change rates ΔAmin1 and ΔAmin2 can be expressed by the change rate ΔAi, and the sum of the change rates ΔAmin1 and ΔAmin2 is constant from the time T1 as the absolute value of the change rate ΔAi. is there. The sum of ΔAmin1 and ΔAmin2 is the rate of change of the minimum flow path area Amin related to the fuel injection amount. Therefore, the change rate of the minimum flow path area Amin in the third embodiment is constant.

(effect)
With reference to FIG. 26, the fuel injection amount Q of 3rd Embodiment is demonstrated. As with the first embodiment, the fuel injection amount Q is calculated from Amin, which is the sum of the minimum flow path areas Amin1 and Amin2, with reference to FIG. 25. The third embodiment is the same as the first embodiment. The effect of. In the third embodiment, by controlling the sliding speed of the inner needle 37 and the outer needle 38 in the valve opening direction, the inclination of the fuel injection amount Q with respect to time, that is, the rate of change of the fuel injection amount can be made constant. it can. This means that the fuel injection amount can be controlled with higher accuracy.

  Among them, in the engine system, exhaust gas regulations are increasing, and particularly advanced control is required in order to realize a good combustion state in the combustion chamber. Therefore, according to the present embodiment, it is particularly effective to make the fuel injection amount highly accurate.

(Other embodiments)
(A) In the first embodiment, only the inner needle 37 may be opened, and fuel may be injected only from the first injection hole 121. Similarly, in the second embodiment, only the outer needle 38 may be opened and fuel may be injected only from the second injection hole 122. The same effects as in the above embodiment are achieved.

  When the inner needle 37 and the outer needle 38 slide, friction between the inner needle collar 371 and the outer needle 38 occurs. At the same time, friction occurs between the housing flange 101 and the outer needle 38. The inner needle collar 37 and the housing collar 101 are worn by friction. Due to the wear, the inlet hole channel 383 and the outlet hole channel 385 in which the inner needle collar 371 and the housing collar 101 are opened and closed change, and the channel areas Ao and Ai change. As described above, the fuel injection amount is greatly affected by the flow path area.

  The inner needle 37 and the outer needle 38 are accommodated coaxially and have an auxiliary role of holding the shaft. For this reason, the radial sliding position accuracy is high. Therefore, the inner needle collar 371, the housing collar 101, and the communication hole 381 of the outer needle 38 are not decentered, there is no contact with shoulders, and the influence of wear due to sliding is reduced. Accordingly, the auxiliary role of holding the shafts of the inner needle 37 and the outer needle 38 is great.

(A) As shown in FIGS. 27A and 27B, the number of communication holes 381 may be eight at regular intervals.
(C) As shown in FIGS. 28 (a) and 28 (b), the number may be two.
(D) Like the form shown to Fig.29 (a), (b), arrangement | positioning of the four communicating holes 381 may not be equidistant.
(E) As shown in FIGS. 30A, 30B, 30C, and 30D, the cross-sectional shape in the radial direction of the communication hole 381 may be a circle, a parallelogram, and an ellipse. Further, the cross-sectional shape in the radial direction of the communication hole 381 may be a rhombus or a square.
As described above, the same effects as those of the above embodiment can be obtained regardless of the number, arrangement, and shape of the communication holes.

  (F) The thermal cycle to which the present embodiment is applied is not limited to the sabatate cycle. For example, the same effect is exhibited in a thermal cycle having a constant pressure heating process such as a diesel cycle, an Ericsson cycle, and a gas turbine cycle.

  (G) As in the third embodiment, the speed variable mechanism of the drive unit 90 that makes the speeds of the inner needle and the outer needle variable may use a solenoid coil. For example, the voltage applied to the solenoid may be controlled to adjust the magnetic attractive force, and the fuel pressure in the first back pressure chamber 21 may be controlled. Further, the drive unit 90 may be a direct acting actuator that directly connects the inner needle 37 and the outer needle 38 to the drive unit 90 and operates them.

(H) As shown in FIG. 31, a reverse formed from an elastic member at the distal end portion 387 of the outer needle 38 disposed at the rear end side from the first injection hole 121 and at the front end side from the second injection hole 122. A stop valve 388 may be further provided. The elastic member is, for example, a stainless steel spring plate or rubber. The check valve 388 expands and contracts when the outer needle 38 is opened and closed using the elastic force of the elastic member. Further, when the outer needle 38 is closed, the check valve 388 contacts the housing 10 between the first nozzle hole 121 and the second nozzle hole 122 to block the second flow path.
By further including the check valve 388, when the inner needle 37 and the outer needle 38 are opened, the flow rate through the first flow path 27 can be prevented from flowing back to the second flow path. Thereby, the precision of each injection quantity from the 1st nozzle hole 121 and the 2nd nozzle hole 122 improves.

  (K) As shown in FIG. 32, the wear-resistant coding 374 may be applied to the end surface 373 of the inner needle collar 371 that contacts the outlet surface 384 of the communication hole 381. Further, the wear-resistant coating 104 may be applied to the end surface 103 of the housing flange 101 that contacts the inlet surface 382 of the communication hole 381. For the wear resistant coating, for example, DLC (diamond-like carbon) or CNx (carbon nitride) is used. These are known as coatings having excellent wear resistance. Alternatively, coating may be performed by PVD methods such as sputtering and ion beam evaporation, and plasma CVD methods such as RF plasma and surface wave excitation plasma (SWP). Further, the wear resistant codings 374, 104 may be coded simultaneously with the inner surface 102 of the housing 10.

  When the inner needle 37 and the outer needle 38 slide repeatedly, the flow passage areas Ao and Ai change due to wear of the inner needle collar 371 and the housing collar 101. The wear-resistant codings 374 and 104 suppress wear of the inner needle collar 371 and the housing collar 101 caused by repeated sliding. Therefore, highly accurate control of the fuel injection amount can be maintained.

  (E) As shown in FIG. 33, in the first embodiment, the third flow path 29 may be used by contacting the housing 10 when the inner needle 37 is closed instead of the first flow path 27. . The same effect is produced.

  As mentioned above, this invention is not limited to such embodiment, In the range which does not deviate from the meaning of invention, it can implement with a various form.

1 ... Fuel injection device,
10 ・ ・ ・ Housing,
101 ... Housing collar,
102 ... Inner surface (housing),
121 ... 1st nozzle hole,
122 ... the second nozzle hole,
27 ... 1st flow path,
28 ... the second flow path,
29 ... the third flow path,
37 ・ ・ ・ Inner needle,
371 ... inner needle buttocks,
372 ... Outer surface (inner needle),
38 ・ ・ ・ Outer needle,
381 ... Communication hole,
382 ... entrance surface,
383 ... inlet hole flow path,
384 ... exit surface,
385 ... outlet hole channel,
391 ... inner surface (outer needle),
392 ... Outer surface (outer needle).

Claims (11)

A first injection hole (121) for injecting fuel and a second injection hole (122) for injecting fuel located at the rear end side of the first injection hole are provided at the bottomed cylindrical tip. A housing (10) having;
The second nozzle hole is slidably accommodated inside the housing and can be opened and closed with axial sliding. The side wall includes an inner side surface (391) and an outer side surface (392) of the side wall. An outer needle (38) having at least one communication hole (381) communicating with
An inner needle (37) that is slidably accommodated inside the outer needle and that can open and close the first nozzle hole in accordance with axial sliding;
With
The inner needle protrudes from the outer surface (372) of the inner needle and passes along the outlet surface (384) of the communication hole when the inner needle or the outer needle slides. Have
The housing has a housing flange (101) protruding from the inner surface (102) of the housing and passing along the inlet surface (382) of the communication hole when the outer needle slides,
A first flow path (27) is formed between the inner needle and the outer needle,
A second flow path (28) is formed between the outer needle and the housing;
A third flow path (29) is formed between the inner needle and the housing,
An outlet hole channel (385) is formed by the inner needle flange and the outlet surface of the communication hole,
A fuel injection device in which an inlet hole channel (383) is formed by the housing flange and the inlet surface of the communication hole.   When the inner needle slides, the rate of change (ΔAo) of the channel area (Ao) of the outlet hole channel is the rate of change of the channel area (A1) of the first channel. The fuel injection device according to claim 1, wherein the fuel injection device is formed to be smaller than (ΔA1).   When the outer needle slides, the inner needle collar portion has a rate of change (ΔAo) in the channel area (Ao) of the outlet hole channel and a rate of change in the channel area (A2) of the second channel. The fuel injection device according to claim 1, wherein the fuel injection device is formed to be smaller than (ΔA2).   When the inner needle slides, the rate of change (ΔAo) of the channel area (Ao) of the outlet hole channel is the rate of change of the channel area (A3) of the third channel. The fuel injection device according to claim 1, wherein the fuel injection device is formed to be smaller than (ΔA3).   When the outer needle slides, the housing flange portion has a rate of change (ΔAi) of the channel area (Ai) of the inlet hole channel (rate of change of the channel area (A2) of the second channel ( The fuel injection device according to claim 1, wherein the fuel injection device is formed to be smaller than ΔA2).   The outlet hole channel is configured such that the channel area (Ao0) of the outlet hole channel when the inner needle and the outer needle are closed is smaller than the channel area (Ah1) of the first nozzle hole. The fuel injection device according to claim 2 or 4, wherein the fuel injection device is formed.   The outlet hole channel is configured such that the channel area (Ao0) of the outlet hole channel when the inner needle and the outer needle are closed is smaller than the channel area (Ah2) of the second nozzle hole. The fuel injection device according to claim 3 or 5, wherein the fuel injection device is formed.   The fuel injection device according to any one of claims 1 to 7, wherein the outer needle has a plurality of communication holes at the same height in the axial direction.   The fuel injection device according to claim 8, wherein the plurality of communication holes are arranged at equal intervals in the circumferential direction. A drive unit (90) for controlling sliding of the outer needle and the inner needle;
The fuel injection device according to any one of claims 1 to 9, wherein the drive unit includes a speed variable mechanism that varies a sliding speed of the outer needle and the inner needle.   When the outer needle is closed, the outer needle is inserted into the first needle 387 at the distal end portion (387) of the outer needle valve, which is rearward of the first nozzle hole and distal of the second nozzle hole. The fuel injection device according to any one of claims 1 to 10, further comprising a check valve (388) that contacts the housing between the hole and the second injection hole to close the second flow path.

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