JP4239945B2 - Fuel injection valve - Google Patents

Description

  The present invention relates to a fuel injection valve, and is suitably applied to, for example, a fuel injection valve that injects and supplies fuel to an internal combustion engine.

  Conventionally, for example, fuel injection valves that inject fuel into a cylinder of a diesel engine are known (see Patent Documents 1 and 2). The characteristics, shape, and the like of the fuel spray injected from the fuel injection valve are optimal depending on the operating state of the engine.

  As a means for realizing the above, in Patent Document 1, for example, needles and valve seats as two sets of valve portions, nozzle holes shared by them, and control for alternately opening the needles for fuel injection from the nozzle holes There is disclosed a technique in which an apparatus is provided and the fuel is alternately injected during one cycle of fuel injection. The control device is generally for independently driving the needles hydraulically, and controls the hydraulic pressure in the back pressure chamber as the hydraulic chamber corresponding to each needle.

In Patent Document 2, two needles arranged inside and outside double, a valve seat shared by these needles, a valve seat formed with a nozzle hole corresponding to each needle, and the needles are alternately opened. Thus, a technique for changing the opening area of the nozzle hole is disclosed.
JP-A-62-118055 JP-A-4-232375

  In the prior art disclosed in Patent Document 1, a back pressure chamber corresponding to each needle and a control device that independently controls the hydraulic pressure of these back pressure chambers are required, which may complicate the system. In addition, since the plurality of valve portions are built in, the physique becomes large and it is difficult to mount the engine on the engine.

  In the prior art disclosed in Patent Document 2, it is possible to prevent the body from becoming large because the two needles are arranged inside and outside, but the fuel of the hydraulic source leaks from the sliding portion between the needles. There was a risk of outflow from the nozzle hole.

  The present invention has been made in view of such circumstances, and the object thereof is to prevent fuel leakage from the nozzle hole due to leakage from the sliding portion between the needles and to prevent the size of the body from increasing. An object of the present invention is to provide a fuel injection valve having a simple configuration.

  In order to achieve the above object, the present invention comprises the following technical means.

That is, according to the first to third aspects of the present invention, there are provided a first seal portion and a second seal portion that block and allow the flow of fuel, and a nozzle body having an injection hole disposed on the downstream side of these seal portions. A nozzle needle that is accommodated in the nozzle body so as to be reciprocally movable, and has a first needle and a second needle that are separated and seated on the seal portion, and a pressure source that applies a pressure in the seating direction to the nozzle needle,
The first seal portion and the second seal portion are formed by different first valve seats corresponding to the first seal portion and second valve seats corresponding to the second seal portion,
Pressure source, first needle and the second needle is characterized by Tei Rukoto has a pressure control chamber to be shared.

  According to this, the nozzle hole provided in the nozzle body is opened and closed independently by the first needle and the second needle constituting the nozzle needle. That is, in the case where the nozzle hole provided in the nozzle body is opened and closed independently by the first needle and the second needle constituting the nozzle needle, the first seal portion and the second seal portion are different from each other. Since the first valve seat corresponding to the first seal portion and the second valve seat corresponding to the second seal portion are formed, the fuel leaked from the sliding portion between the first needle and the second needle Can be prevented from flowing out of the nozzle hole.

Furthermore, since the pressure source that applies the pressure in the seating direction to the nozzle needle has a pressure control chamber shared by the first needle and the second needle, it is possible to provide a simple configuration that can prevent the physique from becoming large .

In the first aspect of the invention, one of the first needle and the second needle is slidably disposed inside the other needle offset from the axial center of the other needle. It is characterized by.

  In general, when one needle is accommodated inside the other needle, for example, when the first needle and the second needle are arranged inside and outside, the first valve seat corresponding to the first seal portion; There is a possibility that the second valve seat corresponding to the second seal portion is shared by one valve seat.

On the other hand, in the invention according to claim 1, one of the first needle and the second needle is slidably disposed inside the other needle offset from the axial center of the other needle. Therefore, the first seal portion and the second seal portion are surely formed by different first and second valve seats.

The invention according to claim 2 is characterized in that the radial cross-sectional area of one of the first needle and the second needle is smaller than the radial cross-sectional area of the other needle. .

  According to this, since the radial cross-sectional area of either one of the first needle and the second needle is formed smaller than that of the other needle, the nozzle needle composed of the first needle and the second needle The enlargement of the physique in the substantially radial direction is suppressed.

  Further, since the radial cross-sectional areas of the first needle and the second needle are different, the valve opening pressures of the first needle and the second needle can be changed. As a result, the characteristics and shape of the fuel spray such as the injection rate can be made variable. .

Further, the invention according to claim 3 is characterized in that the first seal portion and the second seal portion are shifted in the axial direction.

  In general, between the nozzle hole corresponding to the first seal part and the nozzle hole corresponding to the second seal part, the first seal part and the second seal part are close to each other in order to reduce the size of the body. Therefore, the arrangement of the nozzle holes may be difficult.

On the other hand, in the invention according to claim 3 , since the first seal portion and the second seal portion are shifted in the axial direction, the proximity state between the first seal portion and the second seal portion is alleviated. I can plan.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments in which a fuel injection valve of the present invention is embodied will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a schematic cross-sectional view showing a fuel injection valve of the present embodiment. FIG. 2 is a cross-sectional view showing the first needle and the second needle in FIG. FIG. 3 is a cross-sectional view showing a tip portion on the nozzle hole side of the nozzle body in FIG. FIG. 4 is a cross-sectional view showing an inner periphery around the first needle and the second needle of the nozzle body in FIG.

  A fuel injection valve 10 shown in FIG. 1 is inserted and mounted in a cylinder head of an engine (not shown), and is configured to inject directly into each cylinder of the engine. Specifically, the fuel injection valve 10 has a substantially cylindrical shape, receives fuel from a fuel introduction portion (not shown) (in the direction of the arrow indicating fuel inflow in the figure), and from the tip via an internal fuel passage (see FIG. 1). Inject fuel. The fuel injection valve 10 includes a valve portion that blocks and allows fuel injection, and an electromagnetic drive portion that drives the valve portion, and fuel that has flowed into the fuel passage from the fuel introduction portion through the valve portion to the engine cylinder. Supply to the jet.

  Note that high-pressure fuel supplied from a fuel injection pump (not shown) through a fuel pipe to a common rail (not shown) is accumulated at a constant high pressure in the common rail, and passes through the fuel pipe to the fuel injection valve 10 disposed in each cylinder. It is introduced into the fuel introduction part. Of the introduced fuel, surplus fuel is returned to a fuel tank (not shown) via a fuel outlet (not shown) (in the direction of the arrow indicating fuel return in the figure). A fuel injection pump (not shown) is provided to adjust the fuel discharge pressure in accordance with the engine speed, load, intake fuel pressure, intake air amount, cooling water temperature, and the like.

  As shown in FIG. 1, the fuel injection valve 10 includes a nozzle body 20, a first needle 50 and a second needle 60 that are accommodated in the nozzle body 20 so as to be reciprocally movable, and an electromagnetic valve 90. . The nozzle body 20, the first needle 50, and the second needle 60 constitute a valve portion that blocks and allows fuel injection. The electromagnetic valve 90 constitutes an electromagnetic drive unit that drives the valve unit by hydraulic pressure. Moreover, the 1st needle 50 and the 2nd needle 60 comprise the nozzle needle accommodated in the nozzle body 20 so that reciprocation is possible.

  As shown in FIG. 1, the nozzle body 20 is a bottomed, generally hollow cylindrical body, and includes a guide hole 20 a that accommodates the first needle 50 and the second needle 60 in a reciprocating manner therein, and a valve seat 21. , 22, nozzle holes 30, 40, and sack portions 27, 28 are formed. This guide hole 20a extends in the axial direction inside the nozzle body 20, and accommodates the first needle 50 and the second needle 60 so as to be independently movable in the axial direction. Further, the guide hole 20 a has one end connected to a back pressure chamber 70 as a pressure control chamber, and the other end connected to the valve seats 21 and 22.

  As shown in FIG. 1, the valve seats 21 and 22 have a substantially truncated cone surface, one end on the large diameter side is continuous with the guide hole 20a, and the other end on the small diameter side is connected to the sack portions 27 and 28. ing. Specifically, a contact portion 51 of the first needle 50 is disposed on a valve seat (hereinafter referred to as a first valve seat) 21 so as to be capable of contacting and separating. A contact portion 61 of a second needle 60 is disposed on a valve seat (hereinafter referred to as a second valve seat) 22 so as to be capable of contacting and separating. The contact portions 51 and 61 are theoretically circular.

  Here, the contact portions 51 and 61 and the first valve seat 21 and the second valve seat 22 corresponding to the contact portions 51 and 61 are the contact portions 51 and 61, respectively. By making contact with and separating from the two valve seats 22, a substantially circular first seal portion S <b> 1 and a second seal portion S <b> 2 that block and allow fuel flow are configured. In the present embodiment, the first seal portion S1 and the second seal portion S2 are arranged so as not to overlap as shown in FIGS.

  The sac portions 27 and 28 are sac holes formed in a bag shape with a small space volume on the tip side of the nozzle body. The opening side of the sack hole continues to the small diameter side of the valve seats 27 and 28. Here, the sac portions 27 and 28 constitute a sac chamber having a bag-like predetermined space volume.

  As shown in FIG. 1, the nozzle holes 30 and 40 are formed as passages that allow the inside and outside of the nozzle body 20 to communicate with the sac portions 27 and 28. Here, the nozzle hole (hereinafter referred to as the first nozzle hole) 30 is arranged on the downstream side of the first valve seat 21, that is, the first seal portion S1, and is blocked and allowed by the first seal portion S1. Constitutes a first fuel injection means for injecting fuel. An injection hole (hereinafter referred to as a second injection hole) 40 is disposed downstream of the first valve seat 22, that is, the second seal portion S2, and injects fuel that is blocked and allowed by the second seal portion S2. A second fuel injection means is configured.

  In addition, when there are a plurality of nozzle holes 30 and 40, as shown in FIG. 3, the nozzle holes 30 and the nozzle holes 40 are arranged so as to intersect each other so as not to be connected.

  As shown in FIG. 1, the oil sump chamber 24 is formed in an annular recess in the middle portion of the inner wall that forms the guide hole 20 a. A fuel supply passage 22 through which fuel is supplied is connected to the oil reservoir chamber 24. The oil sump chamber 24 divides the guide hole 20a into an upper part of the guide hole and a lower part of the guide hole in the axial direction.

  The first needle 50 is formed in a substantially cylindrical shape, and is loosely fitted in the guide hole 20a through a predetermined gap. A first upper end surface 53 that receives the hydraulic pressure in the back pressure chamber 70 is formed on the side opposite to the nozzle hole of the first needle 50, and the first valve 50 faces the first valve seat 21 on the nozzle hole side of the first needle 50, A substantially conical first lower end surface 54 is formed. The first lower end surface 54 is disposed on the inner peripheral side with respect to the contact portion 51, and is disposed on the outer peripheral side with respect to the first lower end surface inner peripheral portion 54 a formed in a truncated cone shape and the contact portion 51. It is comprised from the 1st lower end surface outer peripheral part 54b formed in the cone shape. When the contact portion 51 is seated and separated from the first valve seat 21, the first needle 50 is closed and opened, so that the fuel from the first injection hole 30 is blocked and allowed.

  A first spring 59 as an urging means is disposed between the first upper end surface 53 and the back pressure chamber 70, and the first spring 59 is first in the seating direction for seating on the first valve seat 21. The upper end surface 53 is configured to be biased. By adjusting the pressure in the back pressure chamber 70, the first needle 50 is reciprocated in the axial direction. A fuel passage 25 is formed between the outer periphery of the first needle 50 and the inner periphery of the guide hole 20a of the nozzle body 20 facing the outer periphery (see FIG. 4). More specifically, it is a step passage formed in a concave shape on the inner wall of the guide hole 20a. The fuel passage 25 constitutes a fuel path that guides the high-pressure fuel supplied through the oil reservoir chamber 24 to the first injection hole 30 side.

  The second needle 60 is formed in a substantially cylindrical shape, and is loosely fitted into the guide hole 20a through a predetermined gap. A second upper end surface 63 that receives the hydraulic pressure in the back pressure chamber 70 is formed on the side opposite to the nozzle hole of the second needle 60, and the second valve seat 22 is opposed to the nozzle hole side of the second needle 60, A substantially conical second lower end surface 64 is formed. The second lower end surface 64 is disposed on the inner peripheral side with respect to the contact portion 61, and is disposed on the outer peripheral side with respect to the second lower end surface inner peripheral portion 64 a formed in a truncated cone shape and the contact portion 61. It is comprised from the 2nd lower end surface outer peripheral part 64b formed in the cone shape. When the contact portion 61 is seated and separated from the second valve seat 22, the second needle 60 is closed and opened, so that the fuel from the second injection hole 40 is shut off and allowed.

  Between the second upper end surface 63 and the back pressure chamber 70, a second spring 69 is disposed as an urging means, and the second spring 69 is second in the seating direction in which the second valve seat 22 is seated. The upper end surface 63 is configured to be biased. By adjusting the pressure in the back pressure chamber 70, the second needle 60 is reciprocated in the axial direction. A fuel passage 26 is formed between the outer periphery of the second needle 60 and the inner periphery of the guide hole 20a of the nozzle body 20 facing the outer periphery (see FIG. 4). More specifically, it is a step passage formed in a concave shape on the inner wall of the guide hole 20a. The fuel passage 26 constitutes a fuel path that guides the high-pressure fuel supplied through the oil reservoir chamber 24 to the second injection hole 40 side.

  In the present embodiment, as shown in FIGS. 1 and 2, the first needle 50 and the second needle 60 are configured so as to be in sliding contact with each other so that the first needle 50 and the second needle can move substantially in the axial direction. Yes. Specifically, as shown in FIG. 2, the first needle 50 and the second needle having a substantially circular cross-sectional shape are partly formed in a flat shape. The plane 50a of the first needle 50 and the plane 60a of the second needle 60 are arranged to face each other, and the plane 50a and the plane 60a are arranged so as to be slidable in the axial direction.

  A fuel supply passage 22 and a return passage 29 are connected to the back pressure chamber 70. A first inlet throttle 71 is provided at the inlet, and a first outlet throttle 72 is provided at the outlet. The fuel supply passage 22 is branched in the middle to supply high-pressure fuel to the back pressure chamber 70 and the oil reservoir chamber 24. The return passage 29 is connected to a return fuel path for returning surplus fuel in the back pressure chamber 70 to the fuel tank. An electromagnetic valve 90 is provided on the downstream side of the return fuel path to switch communication between the return path 23 and the low pressure path on the fuel tank side. By adjusting the area ratio of the flow path cross-sectional area of the first inlet throttle 71 and the first outlet throttle 72 by the electromagnetic valve 90, the balance between the inflow amount and the outflow amount of the high-pressure fuel into the back pressure chamber 70 can be adjusted. Accordingly, the fuel pressure increase / decrease speed in the back pressure chamber 70 is adjusted.

  Here, the back pressure chamber 70 constitutes a common pressure control chamber that applies a seating direction pressure to the first upper end surface 53 of the first needle 50 and the first upper end surface 63 of the second needle 60.

  The electromagnetic valve 90 includes a control valve 91, and a solenoid 92 and a third spring 93 are provided above the control valve 91. When the drive current is not supplied to the solenoid 92, the control valve 91 is seated on a valve seat (not shown) by the urging force of the third spring 93 and the return passage 29 is blocked. When the drive current is supplied, the control valve 91 is separated from the valve seat by the exciting suction force generated in the solenoid 92 and opens the return passage 29. The drive current is supplied to the solenoid 92 at a timing determined according to the operating state of the engine by an engine control unit (ECU) (not shown).

  Here, the conditions for opening and closing the first needle 50 and the second needle 60 will be described. Since the first needle 50 and the second needle 60 are basically the same in configuration, only the first needle 50 will be described here. The pressure Pu of the back pressure chamber 70 and the urging force Fs of the first spring 59 act on the first upper end surface 53 in the seating direction of the first valve seat 21. On the other hand, the pressure of high-pressure fuel (hereinafter referred to as common rail pressure) Pd supplied from the common rail acts on the first lower end surface 54 in response to opening and closing of the valve. Specifically, under the valve opening conditions, the first needle 50 is closed, that is, the contact portion 51 is seated on the second valve seat and the first seal portion S1 is sealed, so the common rail pressure Pd Acts on the outer peripheral portion 54b of the first upper end surface. Under the valve closing condition, the first needle 50 is opened, so the common rail pressure Pd acts on the first upper end surface outer peripheral portion 54b and the second upper end surface inner peripheral portion 54a, that is, the first upper end surface 54.

  The pressure receiving areas of the first upper end surface 53, the first lower end surface outer peripheral portion 54b, and the first lower end surface 54 are A53, A54o, and A54c, respectively. The outer diameter of the first needle 51 (specifically, the first upper end surface 53 and the first lower end surface 54) is D50, and the diameter of the contact portion 51 (hereinafter referred to as the seal diameter) is D50s. From the above balance condition, the valve opening condition is A54o × Pd> A53 × Pu + Fs, and the valve closing condition is A54c × Pd> A53 × Pu + Fs. Therefore, the valve opening pressure and the valve closing pressure of the first needle 50 vary depending on the pressure receiving area A53, the seal diameter D50s, that is, the pressure receiving area A54o, the biasing force Fs due to the spring size of the first spring 59, and the like.

  For the second needle 60, the pressure receiving areas of the second upper end surface 63, the second lower end surface outer peripheral portion 64b, and the first lower end surface 64 are A63, A64o, and A64c, respectively, and the outer diameter of the second needle 60 is Let D60 be the seal diameter D60s of the contact portion 61. Since the valve opening condition is A64o × Pd> A63 × Pu + Fs and the valve closing condition is A64c × Pd> A63 × Pu + Fs, the valve opening pressure and the valve closing pressure of the second needle 60 are the pressure receiving area A63. The sheet diameter D60s, that is, the pressure receiving area A64o, and the urging force Fs due to the spring size of the second spring 69 and the like change.

  In the above description, the pressure receiving area does not indicate the actual surface area of each surface, but a shaft for receiving the acting force of the pressure Pu and the common rail pressure Pd so that the needles 50 and 60 move in the axial direction. Direction projected area. For example, the valve opening pressure can also be adjusted by adjusting the area ratio between the pressure receiving area A63 of the second upper end face 63 of the second needle 60 and the pressure receiving area A64o of the second lower end face outer peripheral part 64b. The first needle 50 and the second needle 60 can be opened independently, or the first needle 50 and the second needle 60 can be opened almost simultaneously. In the following description of the valve opening pressure of the first needle 50 and the second needle 60, it is assumed that the valve opening pressure is different and the valve opening pressure of the first needle 50 is larger than the valve opening pressure of the second needle 60.

  The operation of the fuel injection valve 10 having the above-described configuration will be described below. FIG. 1 shows when fuel injection is stopped.

(When injection stops)
The relatively high-pressure fuel accumulated in the common rail is supplied to the back pressure chamber 70 and the fuel passage 25 through the fuel supply passage 22 as shown in FIG. At this time, since the drive current is not supplied to the solenoid 92, the control valve 91 is seated on the valve seat by the urging force of the third spring 93 to block the return passage 29. Since the supplied fuel stays in the back pressure chamber 70, the fuel pressures in the first and second pressure control chambers 70, 80 and the fuel passages 25, 26 are substantially equal. Since the urging force for pressing the first needle 50 against the first valve seat 21 is larger than the urging force for lifting, the contact portion 51 is seated on the first valve seat 21, The fuel is not injected from the first injection hole 30. Further, since the urging force for pressing the second needle 60 against the second valve seat 22 is larger than the urging force for lifting, the contact portion 61 is seated on the second valve seat 22 and the fuel passage 26. The fuel inside is not injected from the second injection hole 40.

  At this time, the first needle 50 and the second needle 60 are kept closed, and the fuel leaking from the sliding portion between the first needle 50 and the second needle 60 is the first seal portion S1. The flow can be blocked downstream by the second seal portion S2, so that the leaked fuel can be prevented from flowing out from the first injection hole 30 and the second injection hole 40.

(Operation to the opening of the first nozzle hole and the second nozzle hole)
When a drive current is supplied to the control valve 91 to the solenoid 92, the control valve 91 is lifted by the magnetic attractive force generated by the solenoid 92, and the return passage 23 is opened. When the return passage 23 is opened, the fuel pressure in the back pressure chamber 70 decreases. The pressure decreases at a predetermined lowering speed according to the area ratio of the first inlet throttle 71 and the first outlet throttle 72. When the fuel pressure in the back pressure chamber 70 decreases to the valve opening pressure of the second needle 60, the second needle 60 is lifted, the contact portion 61 is separated from the second valve seat 22, and the second needle 60 is opened. To be spoken. When the second needle 60 is opened, the fuel in the fuel passage 26 flows into the second injection hole 40 and the fuel is injected from the second injection hole 40.

  Since the valve opening pressure of the first needle 50 is higher than the valve opening pressure of the second needle 60, the contact portion 51 is seated on the first valve seat 21 and the first seal portion S1 is sealed. As a result, the valve opening of the first needle 50 is maintained, and fuel does not flow out from the first nozzle hole 30. At this time, since the fuel is injected only from the second injection hole 40, the injection rate as the fuel injection characteristic is in a relatively low state.

  Next, when the pressure in the back pressure chamber 70 decreases to the valve opening pressure of the first needle 50, the first needle 50 is lifted, the contact portion 51 is separated from the first valve seat 21, and the first needle 50 Is opened. When the first needle 50 is opened, the fuel in the fuel passage 25 flows into the first injection hole 30 and the fuel is injected from the first injection hole 30. At this time, since the fuel is injected from both the first injection hole 30 and the second injection hole 40, the injection rate is higher than that at the time of fuel injection from the second injection hole 40 alone.

(Operation to stop injection)
When a predetermined valve opening time corresponding to the operating state of the engine has elapsed, the supply of drive current to the solenoid 92 is stopped. When the supply of the drive current is stopped, the magnetic attractive force of the solenoid 92 is lost and the control valve 91 blocks the return passage 23. Then, since the fuel outflow from the first outlet throttle 72 to the downstream is stopped, the pressure in the back pressure chambers 70 and 80 starts to rise again. When the pressure in the back pressure chambers 70, 80 rises to the valve closing pressure of the first needle 50, the first needle 50 closes, and when it rises to the valve closing pressure of the second needle 60, the second needle 60 closes. . As a result, fuel injection from the first nozzle hole 30 and the second nozzle hole 40 is stopped.

  Next, the operation and effect of this embodiment will be described. (1) In this embodiment, the nozzle holes 30 and 40 provided in the nozzle body 20 are opened and closed independently by the first needle 50 and the second needle 60. The first valve seat corresponding to the first seal portion S1 is different from each other in the first seal portion S1 and the second seal portion S2 that block and allow the flow of fuel to the nozzle hole. 21 and a second valve seat 22 corresponding to the second seal portion S2. As a result, the first seal portion S1 and the second seal portion S2 do not overlap, so that fuel leaking from the sliding portion between the first needle 50 and the second needle 60 flows out from the nozzle holes 30 and 40. Can be prevented.

  Further, the pressure source that applies the pressure in the seating direction to the first needle 50 and the second needle 60 is formed by the back pressure chamber 70 shared by the first needle 50 and the second needle 60. The fuel circuit that operates in the seating direction and the fuel circuit that operates in the seating direction on the second needle have a simple configuration, and the size of the fuel injection valve 10 can be prevented from increasing in size.

  (2) In the present embodiment, the first needle 50 and the second needle are formed in a substantially circular cross-sectional shape, and a part thereof (specifically, the flat surface 50a and the flat surface 50b) are formed in a flat shape. The first needle 50 and the second needle 60 are configured to slidably contact each other so that the first needle 50 and the second needle can move substantially in the axial direction by the plane 50a and the plane 60a. Since it comprises in this way, it is possible to make the physique of the substantially radial direction of the nozzle needle comprised from the 1st needle 50 and the 2nd needle 60 small compared with what is formed in the conventional circular cross-sectional shape.

(Second Embodiment)
A second embodiment will be described with reference to FIG. In the following description, the same or equivalent components as those in the first embodiment are denoted by the same reference numerals, and description thereof will not be repeated. FIG. 5 is a cross-sectional view showing an example of the inner periphery surrounding the first needle and the second needle of the nozzle body according to the present embodiment.

  In the second embodiment, in the fuel passages 25 and 26 described in the first embodiment, instead of the step passage formed on the inner wall side of the guide hole 20a of the nozzle body 20, as shown in FIG. The step passages are formed on the outer wall side of the first needle 50 and the outer wall side of the second needle 60.

  As shown in FIG. 5, a stepped portion 58 is formed on the outer wall side of the first needle 50. A space defined by the step portion 58 and the guide hole 20a forms the step passage. Further, a stepped portion 68 is formed on the outer wall side of the second needle 60, and a space defined by the stepped portion 68 and the guide hole 20a forms the stepped passage.

  In the present embodiment described above, even when configured in this way, the same effects as those of the first embodiment can be obtained. Further, since the first needle 50 and the second needle 60 can be accommodated in the axial direction by the guide hole 20a, the high-pressure fuel in the back pressure chamber 70 can be kept relatively oil-tight.

(Third embodiment)
In the third embodiment, in the first needle 50 and the second needle 60 that are in sliding contact with each other described in the first embodiment, instead of the one in which the flat surfaces 50a and 60a are in sliding contact with each other, as shown in FIG. It shall be in sliding contact with each other. FIG. 6 is a cross-sectional view showing the first needle and the second needle according to the present embodiment.

  As shown in FIG. 6, the second needle 60 is formed in a circular cross section, and the first needle 50 is formed with a concave curved surface portion 50 b along the outer periphery of the second needle 60.

  In the present embodiment described above, even when configured in this way, the same effects as those of the first embodiment can be obtained. In the present embodiment, the outer periphery of the first needle 50 is formed in the concave curved surface portion 50b along the outer periphery of the second needle 60. However, the first needle 50 is formed in a circular cross-sectional shape and is disposed on the second needle 60 side. A concave curved surface portion 50b may be provided.

(Fourth embodiment)
In general, when one needle is accommodated inside the other needle, such as when the first needle 50 and the second needle 60 are arranged in an inner and outer double, the second needle corresponding to the first seal portion S1. One valve seat 21 and the second valve seat 22 corresponding to the second seal portion S2 may be shared by one valve seat.

  In the fourth embodiment, instead of the first needle 50 and the second needle 60 described in the first embodiment, the second needle 160 is offset inside the first needle 150 as shown in FIG. Deploy. FIG. 7 is a schematic cross-sectional view showing the fuel injection valve of the present embodiment. FIG. 8 is a cross-sectional view showing the first needle and the second needle in FIG.

  As shown in FIGS. 7 and 8, the second needle 160 is slidably disposed inside the first needle 150 that is offset from the axial center. As shown in FIG. 8, the first seal portion S1 corresponding to the first needle 150 and the second seal portion S2 corresponding to the second needle 160 are arranged so as not to overlap each other.

  In the present embodiment described above, since the second needle 160 is disposed inside the first needle 150 that is offset from the axial center, the first seal portion S1 and the second seal portion S2 are disposed so as not to overlap. be able to. This is because the first seal portion S1 and the second seal portion S2 are surely formed by different first valve seat 21 and second valve seat 22. Even if comprised in this way, the effect similar to 1st Embodiment can be acquired.

  Since the second needle 160 is housed inside the first needle 150, the pressure receiving areas such as the first upper end surface 53 and the second upper end surface 63 are set to be different between the second needle 160 and the first needle 150. (See FIG. 8). Thereby, a pressure difference can be reliably provided between the valve opening pressure of the first needle 150 and the valve opening pressure of the second needle 160. Therefore, it is possible to obtain an injection characteristic that makes the injection rate variable, such as so-called boot injection.

(Fifth embodiment)
In the fifth embodiment, between the first needle 50 and the second needle 60 described in the first embodiment, as shown in FIG. 9, the first needle 50 and the second needle 60 are reciprocated substantially in the axial direction. A partition wall 20h that is movable is disposed. FIG. 9 is a schematic cross-sectional view showing the fuel injection valve of the present embodiment. FIG. 10 is a cross-sectional view showing the first needle and the second needle in FIG.

  As shown in FIG. 9, the first needle 50 and the second needle 60 are arranged with a partition wall 20 h that allows the first needle 50 and the second needle 60 to reciprocate substantially in the axial direction.

  Here, generally, in order to accommodate the first needle 50 and the second needle 60 so as to be reciprocally movable, the nozzle body 20 forms the first needle 50 and the second needle 60 by drilling the inside thereof. It is necessary to form a guide hole 20a having a slidable inner periphery.

  On the other hand, in the present embodiment, of the inner periphery of the guide hole 20a, an inner peripheral portion that accommodates the first needle 50 is slidable and an inner peripheral portion that accommodates the second needle 60 is slidable. The barrier ribs 20h can be configured not to overlap each other. Therefore, when drilling the nozzle body 20 or the like, drilling can be easily performed.

  When the partition wall 20 h is disposed between the first needle 50 and the second needle 60, the radial cross-sectional area of one of the first needle 50 and the second needle 60 is made smaller than the other. It is preferable to do so (see FIG. 10). Thereby, the enlargement of the physique of the substantially radial direction of the nozzle needle comprised from the 1st needle 50 and the 2nd needle 60, ie, the fuel injection valve 10, is suppressed.

  Furthermore, since the radial cross-sectional areas of the first needle 50 and the second needle 60 are different, the valve opening pressures of the first needle 50 and the second needle 60 can be changed. As a result, the characteristics and shape of the fuel spray such as the injection rate can be changed. Can be made variable.

  Furthermore, it is preferable that the first seal portion S1 and the second seal portion S2 are shifted in the axial direction (see FIG. 9).

  In general, between the first nozzle hole 30 corresponding to the first seal part S1 and the second nozzle hole 40 corresponding to the second seal part S2, the first seal part S1 and the second seal part 2 are intended to reduce the size of the body. Since the seal part S2 comes close, the arrangement of the nozzle holes 30 and 40 may be difficult.

  On the other hand, in the present embodiment, the first seal portion S1 and the second seal portion S2 are shifted in the axial direction, so that the proximity state between the first seal portion S1 and the second seal portion S2 is alleviated. I can plan. Therefore, the design freedom of the arrangement of the nozzle holes 30 and 40 can be improved, and the nozzle holes 30 and 40 can be easily arranged.

(Sixth embodiment)
In the fifth embodiment, instead of the first needle 50 and the second needle 60 described in the first embodiment, as shown in FIG. The first needle 250 and the second needle 260 are arranged. FIG. 11 is a schematic cross-sectional view showing the fuel injection valve of the present embodiment. 12 is a cross-sectional view showing the first needle and the second needle in FIG.

  As shown in FIG. 11, the first needle 250 and the second needle 260 are arranged such that their axial centers intersect in the direction of the injection hole. The first lower end surface 254 of the first needle 250 includes a first lower end surface inner peripheral portion 254a formed on the inner peripheral side with respect to the first seal portion S1, and a first lower end surface outer peripheral portion formed on the outer peripheral side. 254b. The second lower end surface 264 of the second needle 260 includes a second lower end surface inner peripheral portion 264a formed on the inner peripheral side with respect to the second seal portion S1, and a second lower end surface formed on the outer peripheral side. It is comprised from the outer peripheral part 264b.

  The first lower end surface outer peripheral portion 254b and the second lower end surface outer peripheral portion 264b are formed in a relatively thin taper shape. The first lower end surface outer peripheral portion 254b and the second lower end surface outer peripheral portion 264b are configured to be slidable with each other.

  In the present embodiment described above, the outer periphery between the end portion of the first needle 250 on the first seal portion S1 side and the end portion of the second needle 260 on the second seal portion S2 side is the outer periphery of the first lower end surface. As in the shape of the portion 254b and the second lower end surface outer peripheral portion 264b, it is relatively thin such as a tapered tapered body. As a result, an increase in the size of the fuel injection valve 10 is suppressed.

It is typical sectional drawing which shows the fuel injection valve of the 1st Embodiment of this invention. It is sectional drawing which shows the 1st needle and 2nd needle in FIG. It is sectional drawing which shows the front-end | tip part by the side of the nozzle hole of the nozzle body in FIG. It is sectional drawing which shows the surroundings of the inner periphery which accommodates the 1st needle and 2nd needle of the nozzle body in FIG. It is sectional drawing which shows an Example of the inner periphery circumference which accommodates the 1st needle and 2nd needle of the nozzle body concerning 2nd Embodiment. It is sectional drawing which shows the 1st needle and 2nd needle concerning 3rd Embodiment. It is typical sectional drawing which shows the fuel injection valve of 4th Embodiment. It is sectional drawing which shows the 1st needle and 2nd needle in FIG. It is typical sectional drawing which shows the fuel injection valve of 5th Embodiment. It is sectional drawing which shows the 1st needle and 2nd needle in FIG. It is typical sectional drawing which shows the fuel injection valve of 6th Embodiment. It is sectional drawing which shows the 1st needle and 2nd needle in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Fuel injection valve 20 Nozzle body 21 1st valve seat 22 2nd valve seat 30 1st injection hole 40 2nd injection hole 50 1st needle 51 Contact part 53 1st upper end surface 54 1st lower end surface 54a 1st lower end surface Inner peripheral portion 54b First lower end surface outer peripheral portion 59 First spring 60 Second needle 61 Contact portion 63 Second upper end surface 64 Second lower end surface 64a Second lower end surface inner peripheral portion 64b Second lower end surface outer peripheral portion 69 Second Spring 70 Back pressure chamber (pressure control chamber)
71 First inlet throttle 72 First outlet throttle S1 First seal portion S2 Second seal portion

Claims (3)

A nozzle body having first and second seal portions that block and allow fuel flow, and nozzle holes disposed downstream of the seal portions;
A nozzle needle that is accommodated in the nozzle body so as to be reciprocally movable and has a first needle and a second needle that are separated from and seated on the seal portion;
A pressure source for applying a pressure in the seating direction to the nozzle needle,
The first seal portion and the second seal portion are formed by a first valve seat corresponding to the first seal portion and a second valve seat corresponding to the second seal portion, which are different from each other. And
The pressure source has a pressure control chamber shared by the first needle and the second needle,
One of the first needle and the second needle is slidably disposed inside the other needle offset from the axial center of the other needle . 2. The fuel injection according to claim 1, wherein a radial cross-sectional area of one of the first needle and the second needle is smaller than a radial cross-sectional area of the other needle. valve. 3. The fuel injection valve according to claim 1, wherein the first seal portion and the second seal portion are shifted in an axial direction . 4.

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