JP2010209875A - Fuel injection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection device capable of accurately controlling an injection quantity of fuel. <P>SOLUTION: The fuel injection device 1 includes a nozzle body 40 and an injection control valve 20 capable of advancing and retreating in a first fuel holding chamber 41. The injection control valve 20 provides communication between a first fuel passage 51 and the first fuel holding chamber 41 and shuts off communication between the first fuel holding chamber 41 and a third fuel passage 53 by advancing to a first position, and shuts off communication between the first fuel passage 51 and the first fuel holding chamber 41 and provides communication between the first fuel holding chamber 41 and the third fuel passage 53 by retreating to a second position. The device includes a fifth fuel passage 55 of which the one-end side communicates with a section at a downstream side of the first fuel holding chamber 41 and an upstream side of a communication part of a fourth fuel passage 54 communicating with a needle valve blocking chamber 43, and of which the other end side communicates with the fourth fuel passage 54. The fifth fuel passage 55 suppresses pressure fluctuation caused by the fluctuation of a blocking assist piston 30 by discharging fuel between the third fuel passage 53 and the needle valve blocking chamber 43. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fuel injection device. In particular, the present invention relates to a fuel injection device that is used in a diesel engine and injects fuel supplied at a high pressure from a fuel supply source.

Conventionally, a fuel injection device that injects fuel is used for a diesel engine.
FIG. 7 is a cross-sectional view of a fuel injection device 701 according to a conventional example.
The fuel injection device 701 has a first fuel storage chamber 741, a second fuel storage chamber 742, a needle valve closing chamber 743, and an injection hole 745 extending from the second fuel storage chamber 742 to the outside of the fuel injection device 701. The nozzle body 740, the needle valve 710 held by the needle valve holding portion 746 inside the nozzle body 740, the closing auxiliary piston 730 provided inside the needle valve closing chamber 743 of the nozzle body 740, and the nozzle body 740 And an injection control valve 720 that is held by the injection control valve holding part 744 and can advance and retreat in the first fuel storage chamber 741.

  The nozzle body 740 includes a first fuel passage 751 extending from the fuel supply source to the first fuel storage chamber 741, a second fuel passage 752 extending from the first fuel storage chamber 741 to the second fuel storage chamber 742, and a first fuel storage chamber. A third fuel passage 753 from 741 to the needle valve closing chamber 743 and a fourth fuel passage 754 from the needle valve closing chamber 743 to the low pressure portion outside the fuel injection device 701 are formed.

The injection control valve 720 moves to the first position where the injection control valve 720 moves forward and contacts the inner wall of the first fuel storage chamber 741 on the third fuel passage 753 side. The housing chamber 741 is communicated, and the first fuel housing chamber 741 and the third fuel passage 753 are shut off. Further, the injection control valve 720 moves backward to the second position where the injection control valve 720 contacts the inner wall near the first fuel passage 751, thereby blocking the first fuel passage 751 and the first fuel storage chamber 741, and the first The fuel storage chamber 741 and the third fuel passage 753 are communicated.
The injection control valve 720 includes a substantially cylindrical guide portion 722 that can slide in the injection control valve holding portion 744, and a substantially disk-shaped bowl-shaped enlarged diameter portion 723 that is provided on the distal end side of the guide portion 722. And a substantially cylindrical closing portion 724 provided on the distal end side of the enlarged diameter portion 723.

  The needle valve 710 moves forward and is seated on the nozzle body 740, thereby blocking the second fuel storage chamber 742 and the injection hole 745, and retreating and separating from the nozzle body 740, thereby 742 and the nozzle hole 745 are communicated.

The operation of the fuel injection device 701 is as follows.
Fuel is supplied to the first fuel passage 751 from the fuel supply source. In this state, when the injection control valve 720 is advanced to the first position, the first fuel passage 751 and the first fuel storage chamber 741 communicate with each other, and the first fuel storage chamber 741 and the third fuel passage 753 are blocked. Is done. Therefore, fuel flows from the first fuel passage 751 through the first fuel storage chamber 741 and the second fuel passage 752 into the second fuel storage chamber 742, and the fuel pressure in the second fuel storage chamber 742 increases. Then, due to the fuel pressure in the second fuel storage chamber 742, the needle valve 710 moves backward and separates from the nozzle body 740. As a result, the fuel in the second fuel storage chamber 742 is injected from the injection hole 745.

  On the other hand, when the injection control valve 720 is retracted to the second position, the first fuel passage 751 and the first fuel storage chamber 741 are blocked, and the first fuel storage chamber 741 and the third fuel passage 753 communicate with each other. . Therefore, fuel flows from the second fuel passage 752 through the first fuel storage chamber 741 and the third fuel passage 753 into the needle valve closing chamber 743, and the fuel pressure in the needle valve closing chamber 743 increases. Then, the closing assist piston 730 advances due to the fuel pressure in the needle valve closing chamber 743. When the closing auxiliary piston 730 advances, the inside of the needle valve closing chamber 743 is partitioned by the closing auxiliary piston 730 into a closing auxiliary pressure chamber 7432 communicating with the third fuel passage 753 and a return pressure chamber 7433 on the needle valve 710 side. The Further, the advanced closing assist piston 730 pushes the needle valve 710 forward. As a result, the needle valve 710 is seated on the nozzle body 740 and fuel injection stops.

At this time, the fuel in the closed auxiliary pressure chamber 7432 flows out into the return pressure chamber 7433 formed under the closed auxiliary piston 730 through the minute communication passage 7331 formed in the closed auxiliary piston 730. Then, as the fuel pressure in the closing auxiliary pressure chamber 7432 decreases, the closing auxiliary piston 730 is moved toward the third fuel passage 753 by the spring 731 that urges the closing auxiliary piston 730 and the needle valve 710 in a direction away from each other. Retreat and return to the initial position.
Thus, when fuel injection is stopped (when the injection control valve 720 shifts from the first position to the second position), the fuel in the first fuel storage chamber 741 is transferred to the third fuel passage 753, the needle valve closing chamber 743, And outflow to the outside through the fourth fuel passage 754 is suppressed.

Japanese Patent Application No. 2008-159266

  The injection control valve 720 moves forward from the second position where the injection control valve 720 contacts the inner wall of the first fuel storage chamber 741 near the first fuel passage 751 and contacts the inner wall of the first fuel storage chamber 741 near the third fuel passage 753. When moved to the first position, the third fuel passage 753 and the first fuel storage chamber 741 are blocked by the injection control valve 720. However, depending on the moving speed of the injection control valve 720, when the injection control valve 720 moves from the second position to the first position, fuel flows from the first fuel storage chamber 741 into the third fuel passage 753, This entrained fuel may flow into the needle valve closing chamber 743. Then, the closing assist piston 730 is pressed by the fuel pressure to move forward, and the needle valve 10 may be loaded in the forward direction.

  Further, when the closing auxiliary piston 730, which has advanced by the entrained fuel flowing into the needle valve closing chamber 743, moves to the last retracted position, which is the initial position, by the spring 731, the closing auxiliary pressure chamber 7432 and the third fuel. The fuel in the passage 753 is pushed back to the first fuel storage chamber 741 side. Then, the fuel pushed back to the first fuel storage chamber 541 side may push back the injection control valve 720 located at the first position and leave the first position.

  Thus, the closing assist piston 730 fluctuates due to pressure fluctuations that occur while the injection control valve 720 moves from the second position to the first position. As a result, the injection amount from the nozzle hole 745 fluctuates, and accurate control is achieved. There was a case where it was not possible.

  In the present invention, the injection control valve reverses from the second position where the injection control valve contacts the inner wall near the first fuel passage in the first fuel storage chamber, and contacts the inner wall near the third fuel passage in the first fuel storage chamber. It is an object of the present invention to provide a fuel injection device capable of suppressing pressure fluctuations that occur while moving to one position and accurately controlling the amount of fuel injected.

  (1) A fuel injection device of the present invention (for example, a fuel injection device 1 described later) includes a first fuel storage chamber (for example, a first fuel storage chamber 41 described later) and a second fuel storage chamber (for example, a first fuel storage device described later). 2 fuel storage chamber 42), a third fuel storage chamber (for example, a needle valve closing chamber 43 described later), and an injection hole (for example, an injection hole 45 described later) from the second fuel storage chamber to the outside of the fuel injection device. And a needle valve (for example, a needle valve to be described later) held by a needle valve holding part (for example, a needle valve holding part 46 to be described later) inside the nozzle body. 10) and needle valve opening means (for example, a second fuel storage chamber 42, a stepped portion 13 described later) and a needle valve opening means provided on the tip side of the needle valve holding portion inside the nozzle body and having the second fuel storage chamber. Fuel sump Portion 421) and needle valve closing means (for example, a needle valve closing chamber 43 and a closing auxiliary piston, which will be described later) provided on the proximal end side of the needle valve holding portion inside the nozzle body and having the third fuel storage chamber. 30) and an injection control valve (for example, an injection control valve 20 to be described later) that is held inside the nozzle body and can advance and retreat in the first fuel storage chamber, the nozzle body from a fuel supply source A first fuel passage (for example, a first fuel passage 51 described later) reaching the first fuel storage chamber and a second fuel passage (for example, a first fuel passage 51 described later) from the first fuel storage chamber to the second fuel storage chamber. 2 fuel passage 52), a third fuel passage (for example, a third fuel passage 53 described later) from the first fuel storage chamber to the third fuel storage chamber, and a fuel injection device from the third fuel storage chamber. To the external low pressure section 4 fuel passages (for example, a later-described fourth fuel passage 54), and the injection control valve moves forward to a first position (for example, a later-described first position), thereby the first fuel passage and The first fuel storage chamber communicates with the first fuel storage chamber and the third fuel passage, and the first fuel storage chamber is retracted to a second position (for example, a second position to be described later). The fuel passage and the first fuel storage chamber are shut off, and the first fuel storage chamber and the third fuel passage are communicated. The needle valve is advanced and seated on the nozzle body, thereby allowing the first fuel storage chamber and the first fuel storage chamber to communicate with each other. (2) The fuel storage chamber and the nozzle hole are shut off, retreated and separated from the nozzle body, thereby allowing the second fuel storage chamber and the nozzle hole to communicate with each other. The needle valve is controlled by the fuel pressure in the fuel storage chamber. The needle valve closing means moves backward, the needle valve is advanced by the fuel pressure in the third fuel storage chamber, one end side is downstream from the first fuel storage chamber, and the third fuel storage chamber And a fifth fuel passage (for example, a fifth fuel passage 55 described later) that communicates with the fourth fuel passage upstream of the communicating portion of the fourth fuel passage. Fuel injection device.

According to the invention of (1), the operation of the fuel injection device is as follows.
That is, fuel is supplied from the fuel supply source to the first fuel passage. When the injection control valve is advanced to the first position in this state, the first fuel passage and the first fuel storage chamber communicate with each other, and the first fuel storage chamber and the third fuel passage are blocked.
Fuel flows from the first fuel passage through the first fuel storage chamber and the second fuel passage into the second fuel storage chamber, and the fuel pressure in the second fuel storage chamber rises. Then, the needle valve opening means operates, and the needle valve is retracted by the fuel pressure in the second fuel storage chamber and is separated from the nozzle body. Thereby, the fuel in the second fuel storage chamber is injected from the injection hole.
In the process in which the fuel injection valve advances to the first position, the fuel that has flowed into the third fuel passage or the third fuel storage chamber flows into the fourth fuel passage through the fifth fuel passage, and the outside of the fuel injection device. To be discharged.

  On the other hand, when the injection control valve is retracted to the second position, the first fuel passage and the first fuel storage chamber are shut off, and the first fuel storage chamber and the third fuel passage communicate with each other. Therefore, the fuel flows into the third fuel storage chamber through the first fuel storage chamber and the third fuel passage, and the needle valve is advanced by the needle valve closing means. As a result, the needle valve is seated on the nozzle body, and fuel injection stops.

  A fifth fuel having one end side downstream of the first fuel storage chamber and communicating upstream of the communication portion of the fourth fuel passage in the third fuel storage chamber and the other end communicating with the fourth fuel passage. A passage is provided. As a result, the fuel that has flowed into the third fuel passage and the third fuel storage chamber quickly flows out to the fourth fuel passage via the fifth fuel passage, and the injection control valve advances from the second position to the first position. It is possible to suppress pressure fluctuations that occur in the third fuel passage and the third fuel storage chamber that occur during the process. Then, it is possible to suppress the injection control valve from being pushed back in the backward direction and the needle valve from being loaded in the forward direction.

  (2) The needle valve closing means further includes a closing auxiliary piston (for example, a closing auxiliary piston 30 described later) provided so as to be able to advance and retreat in the third fuel storage chamber, and the closing auxiliary piston is in the last retracted position. The third fuel passage and the third fuel storage chamber are shut off, and the third fuel passage and the third fuel storage chamber are communicated with each other by shifting to the forward movement state. When the closing auxiliary piston is in the forward state, a closing auxiliary pressure chamber (for example, a closing auxiliary pressure chamber 432 described later) that communicates with the third fuel passage by the closing auxiliary piston and a return that communicates with the fourth fuel passage. A pressure chamber (for example, a return pressure chamber 433 described later), and the closing auxiliary piston moves from the advanced state to the last retracted position, and the third fuel passage, the closing auxiliary pressure chamber, By shutting off, the fuel in the first fuel storage chamber is prevented from flowing into the third fuel storage chamber through the third fuel passage, and the fuel in the first fuel storage chamber is prevented from flowing into the fuel injection device. Outflow to the outside is suppressed, and one end side of the fifth fuel passage communicates with the closing auxiliary pressure chamber.

According to the invention of (2), the needle valve closing means has the closing auxiliary piston that advances and retreats in the third fuel storage chamber, and the third fuel passage and the third fuel are located when the closing auxiliary piston is located at the last retracted position. The storage chamber is shut off, and when the closing auxiliary piston moves forward, the third fuel passage and the third fuel storage chamber communicate with each other. The third fuel storage chamber is partitioned into a closing auxiliary pressure chamber and a return pressure chamber when the closing auxiliary piston is in a forward state. And one end side of the 5th fuel passage was supposed to be in communication with the closed auxiliary pressure chamber.
As a result, in the process in which the injection control valve advances to the first position, the fuel that has flowed into the third fuel passage and the closing auxiliary pressure chamber of the third fuel storage chamber passes through the fifth fuel passage to the outside of the fuel injection device. Can be discharged.

  (3) The flow from the first fuel storage chamber side to the third fuel storage chamber side is allowed in the third fuel passage, and the flow from the third fuel storage chamber side to the first fuel storage chamber side is allowed. A check valve (for example, a check valve chamber 531 and a check valve piston 60 described later) is provided, and one end side of the fifth fuel passage is more than a seating portion of the check valve of the third fuel passage. It communicates with the third fuel storage chamber side.

  According to the invention of (3), the check valve is provided in the third fuel passage, and one end side of the fifth fuel passage is communicated with the third fuel storage chamber side rather than the seating portion of the check valve. By providing the check valve, it is possible to prevent the fuel that has flowed from the third fuel passage to the downstream side of the check valve from flowing back into the first fuel storage chamber through the third fuel passage. Further, since the fifth fuel passage communicates with the downstream side of the check valve, the fuel flowing into the third fuel passage can be discharged to the outside of the fuel injection device via the fifth fuel passage.

  According to the present invention, by providing the fifth fuel passage, it is possible to suppress pressure fluctuation that occurs while the injection control valve moves from the second position to the first position, and to perform precise control of the fuel injection amount. A fuel injection device that can be provided can be provided.

It is sectional drawing which shows the structure of the fuel-injection apparatus which concerns on one Embodiment of this invention. FIG. 6 is a diagram (No. 1) for explaining the operation of the fuel injection device according to the embodiment; FIG. 6 is a diagram (No. 2) for explaining the operation of the fuel injection device according to the embodiment; FIG. 6 is a view (No. 3) for explaining the operation of the fuel injection device according to the embodiment. It is sectional drawing which shows the structure of the fuel-injection apparatus which concerns on 2nd Embodiment of this invention. It is sectional drawing which shows the structure of the fuel-injection apparatus which concerns on 3rd Embodiment of this invention. It is sectional drawing which shows the structure of the fuel-injection apparatus which concerns on the prior art example of this invention.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
An overall outline of the fuel injection device 1 will be described with reference to FIG.
FIG. 1 is a cross-sectional view showing a configuration of a fuel injection device 1 according to an embodiment of the present invention. In addition, in the following FIGS. 1-6, the dimension and movement stroke amount of the needle valve 10, the injection control valve 20, and the closing auxiliary piston 30 are drawn exaggerated from the actual for easy understanding.

The fuel injection device 1 is accommodated in a housing (not shown), and injects fuel supplied at a high pressure from a fuel supply source in accordance with the operation of the actuator 70.
The fuel injection device 1 includes a needle valve 10, an injection control valve 20, a spring 21 that biases the injection control valve, a closing assist piston 30 as a needle valve closing means, and a biasing force for the closing assist piston 30. A spring 31 as an elastic member, a check valve piston 60 as a check valve for stopping fuel from flowing backward, and a columnar nozzle body 40 for accommodating them.

  The nozzle body 40 is composed of four members. Inside the nozzle body 40, a first fuel storage chamber 41 and a third fuel passage 53 (to be described later) are arranged in order from the proximal end side to the distal end side. A check valve chamber 531, a needle valve closing means and a needle valve closing chamber 43 as a third fuel storage chamber provided in the middle, and a second fuel storage chamber 42 as a needle valve opening means are formed.

The nozzle body 40 includes a first fuel passage 51 extending from a fuel supply source (not shown) to the first fuel storage chamber 41, a second fuel passage 52 extending from the first fuel storage chamber 41 to the second fuel storage chamber 42, A third fuel passage 53 extending from the one fuel storage chamber 41 to the needle valve closing chamber 43 and a fourth fuel passage 54 extending from the needle valve closing chamber 43 to a low pressure portion (not shown) outside the nozzle body 40 are formed. The third fuel passage 53 is formed with a check valve chamber 531 in which the check valve piston 60 is provided.
Here, examples of the fuel supply source include a high-pressure pump connected via a common rail.
Examples of the low pressure section include a fuel tank, a fuel passage between the low pressure pump and the high pressure pump, and a fuel passage upstream of the pressurizing chamber in the high pressure pump.

The first fuel storage chamber 41 is a substantially cylindrical space extending along the extending direction of the nozzle body 40.
A through hole having a circular cross section reaching the base end surface of the nozzle body 40 is formed in the base end surface of the first fuel storage chamber 41, and this through hole includes an injection control valve holding portion 44 that holds the injection control valve 20 and It has become.
The inner diameter of the injection control valve holding portion 44 is smaller than the inner diameter of the first fuel storage chamber 41, whereby a step portion 411 is formed on the base end surface of the first fuel storage chamber 41.

  The first fuel passage 51 extends from the proximal end surface of the nozzle body 40 to the inner peripheral surface on the distal end side of the injection control valve holding portion 44 that is a through hole.

The needle valve closing chamber 43 is a substantially cylindrical space extending along the extending direction of the nozzle body 40. A stepped portion 431 is formed on the distal end side of the needle valve closing chamber 43 along the circumferential direction. A third fuel passage 53 and a fourth fuel passage 54 are connected to the needle valve closing chamber 43.
The third fuel passage 53 is a through hole that extends from approximately the center of the distal end surface of the first fuel storage chamber 41 to approximately the center of the proximal end surface of the needle valve closing chamber 43. A check valve chamber 531 is formed in the third fuel passage 53, and the needle valve is closed from the upstream third fuel passage 53 a and the check valve chamber 531 through the passage from the first fuel storage chamber 41 to the check valve chamber 531. A passage reaching the chamber 43 is referred to as a downstream third fuel passage 53b.
The fourth fuel passage 54 extends from the inner peripheral surface on the distal end side of the needle valve closing chamber 43 to the proximal end surface of the nozzle body 40.

The check valve chamber 531 is a substantially cylindrical space that is provided in the middle of the third fuel passage 53 and extends along the extending direction of the nozzle body 40. The check valve chamber 531 is provided with a check valve piston 60 and a spring 61 that urges the check valve piston 60 toward the base end side in the extending direction of the check valve chamber 531. 53a, the downstream third fuel passage 53b, and the fifth fuel passage 55 are connected.
The volume of the check valve chamber 531 is formed to be larger than the total volume of the upstream third fuel passage 53a and the downstream third fuel passage 53b.

The base end side in the extending direction of the check valve chamber 531 is formed with an inclined portion 532 that connects with a predetermined angle from the inner surface of the check valve chamber 531 to the upstream third fuel passage 53a. The inclined portion 532 serves as a seating portion with which the proximal end surface of the check valve piston 60 abuts.
The fifth fuel passage 55 is a through hole whose one end side communicates with the inner peripheral surface on the distal end surface side of the check valve chamber 51 and whose other end side communicates with the fourth fuel passage 54. It is formed smaller than the inner diameter of the fuel passage 53b.

The second fuel storage chamber 42 is a substantially cylindrical space extending along the extending direction of the nozzle body 40.
A through hole extending to the outside of the nozzle body 40 is formed on the distal end side of the second fuel storage chamber 42, and this through hole is a nozzle hole 45.
On the proximal end side in the extending direction of the second fuel storage chamber 42, a fuel reservoir portion 421 is formed as a needle valve opening means whose inner periphery is expanded.

A through hole from the needle valve closing chamber 43 to the second fuel storage chamber 42 is formed in the nozzle body 40, and this through hole serves as a needle valve holding portion 46 that holds the needle valve 10.
The second fuel passage 52 extends from the inner peripheral surface of the portion on the tip side of the step portion 411 of the first fuel storage chamber 41 to the fuel reservoir portion 421 of the second fuel storage chamber 42.

The needle valve 10 is held by a needle valve holding portion 46 of the nozzle body 40, and the distal end side of the needle valve 10 extends in the second fuel storage chamber 42 along the extending direction of the second fuel storage chamber 42. It is possible to advance and retreat.
The needle valve 10 includes a cylindrical needle valve main body 11 that is slidably held by the needle valve holding portion 46, and a movement restricting portion 12 that is formed in a bowl shape on the proximal end side of the needle valve main body 11. Prepare.

The proximal end side of the needle valve main body 11 with respect to the needle valve holding portion 46 is exposed in the needle valve closing chamber 43.
The movement restricting portion 12 is formed in a portion of the needle valve main body 11 exposed in the needle valve closing chamber 43.

  The outer diameter of the movement restricting portion 12 of the needle valve 10 is larger than the inner diameter of the portion closer to the proximal end than the stepped portion 431 of the needle valve closing chamber 43. Therefore, when the needle valve 10 is retracted, the movement restricting portion 12 hits the stepped portion 431, and the retreat of the needle valve 10 is restricted.

A step portion 13 as a needle valve opening means is formed in a ring shape along the circumferential direction in a portion of the outer peripheral surface of the needle valve main body 11 located in the vicinity of the fuel reservoir portion 421.
The outer diameter of the portion on the distal end side of the step portion 13 of the needle valve body 11 is smaller than the outer diameter of the portion on the proximal end side of the step portion 13 of the needle valve body 11. A gap through which fuel flows is formed between the outer peripheral surface of the tip side of the step portion 13 and the inner peripheral surface of the second fuel storage chamber 42.

  In the needle valve 10 described above, the distal end surface of the needle valve main body 11 is separated from the distal end side of the second fuel storage chamber 42, whereby the fuel reservoir 421 of the second fuel storage chamber 42 and the second fuel storage chamber 42 are separated. The nozzle hole 45 formed in the tip portion communicates, and the tip surface of the needle valve main body 11 is seated on the tip side of the second fuel storage chamber 42, so that the fuel reservoir 421 of the second fuel storage chamber 42 and the nozzle are injected. The hole 45 is blocked.

The injection control valve 20 is held by the injection control valve holding portion 44 of the nozzle body 40, and the first fuel storage chamber 41 is extended along the extending direction of the first fuel storage chamber 41 by a piezo actuator 70 (not shown). You can move forward and backward.
The injection control valve 20 is formed in a cylindrical shape on the injection control valve main body 22 and a bowl shape on the injection control valve main body 22.
The passage closing portion 23 is formed in a portion of the injection control valve main body 22 exposed to the first fuel storage chamber 41.
The injection control valve main body 22 is slidably held by the injection control valve holding portion 44. A reduced diameter portion 221 is formed in a portion from the portion facing the first fuel passage 51 to the passage closing portion 23 on the outer peripheral surface of the injection control valve main body 22.

  The spring 21 is provided between the front end surface of the first fuel storage chamber 41 and the passage closing portion 23 of the injection control valve 20 and biases the injection control valve 20 in the backward direction.

The state in which the injection control valve 20 moves forward against the biasing force of the spring 21 and the front end surface of the injection control valve main body 22 is in contact with the front end surface of the first fuel storage chamber 41 is a first state of the injection control valve 20. Position.
When the injection control valve 20 is positioned at the first position, the front end surface of the injection control valve main body 22 abuts on the front end surface of the first fuel storage chamber 41, and the step portion 411 between the passage closing portion 23 and the first fuel storage chamber 41. A gap is formed between the two.

  The first fuel passage 51 communicates with the distal end side of the injection control valve holding portion 44 that is a through hole, and the upstream third fuel passage 53a communicates with the distal end surface of the first fuel storage chamber 41. In the state, the first fuel storage chamber 41 and the upstream third fuel passage 53a are blocked, and the first fuel passage 51 and the first fuel storage chamber 41 are communicated.

On the other hand, the state where the injection control valve 20 is retracted and the passage closing portion 23 is in contact with the step portion 411 of the first fuel storage chamber 41 is defined as the second position of the injection control valve 20.
When the injection control valve 20 is positioned at the second position, the passage closing portion 23 abuts on the step portion 411 of the first fuel storage chamber 41, and the front end surface of the injection control valve main body 22 and the front end surface of the first fuel storage chamber 41. Are spaced apart to form a gap. In this state, the first fuel passage 51 and the first fuel storage chamber 41 are blocked, and the first fuel storage chamber 41 and the upstream third fuel passage 53a are communicated.
FIG. 1 shows a state where the injection control valve 20 is located at the second position.

  The closing assist piston 30 is provided so as to be able to advance and retreat in the needle valve closing chamber 43, and has a substantially cylindrical partition portion 33 that slides on the inner wall surface of the needle valve closing chamber 43, and the needle valve 10 side of the partition portion 33. And an auxiliary force transmission portion 32 extending in a rod shape from the end portion.

  The needle valve closing chamber 43 is partitioned by the partition 33 into a closing auxiliary pressure chamber 432 that communicates with the third fuel passage 53 and a return pressure chamber 433 that communicates with the fourth fuel passage 54.

A portion on the base end side of the partition portion 33 has a substantially conical shape protruding toward the upstream side third fuel passage 53a side.
In addition, the partition portion 33 is formed with a minute communication path 331 that allows the closing auxiliary pressure chamber 432 and the return pressure chamber 433 to communicate with each other. The minute communication path 331 is formed between the closing assist piston 30 and the needle valve closing chamber 43 by denting the outer peripheral surface of the partition portion 33 of the closing assist piston 30.

  The spring 31 is provided between the closing assist piston 30 in the needle valve closing chamber 43 and the proximal end side of the needle valve 10, and biases the closing assist piston 30 and the needle valve 10 in a separating direction.

The check valve piston 60 is provided so as to be able to advance and retreat in the check valve chamber 531. The check valve piston 60 hits the inclined portion 532 when retreating, and closes the upstream third fuel passage 53 a, and the tip from the close portion 62. And a support portion 63 that protrudes in a rod shape on the side (downstream third fuel passage 53b side) and abuts against the tip surface of the check valve chamber 531 when moving forward.
The base end side (upstream third fuel passage 53 a side) surface of the blocking portion 62 has a curved surface corresponding to the shape of the inclined portion 532.

  The spring 61 is provided between the check valve piston 60 in the check valve chamber 531 and the distal end surface of the check valve chamber 531, and biases the check valve piston 60 toward the base end side. The biasing force of the spring 61 is preferably smaller than the biasing force of the spring 31 that biases the closing assist piston 30.

The upstream third fuel passage 53 a is a through hole that is formed substantially at the center of the base end surface of the check valve chamber 531 and extends to the first fuel storage chamber 41.
Further, the downstream third fuel passage 53 b is a through hole that is formed in the distal end surface of the check valve chamber 531 in the vicinity of the inner peripheral surface of the check valve chamber 531 and extends to the needle valve closing chamber 43. The downstream third fuel passage 53b is always in the state where the support portion 63 of the check valve piston 60 is in contact with the front end surface of the check valve chamber 531 regardless of the position of the check valve piston 60. The check valve chamber 531 and the needle valve closing chamber 43 communicate with each other.

Hereinafter, operations of the closing assist piston 30 and the check valve piston 60 will be described.
That is, first, a state where the injection control valve 20 is located at the first position and the first fuel storage chamber 41 and the upstream third fuel passage 53a are blocked will be described.
At this time, the check valve piston 60 is separated from the first fuel storage chamber 41 and the upstream third fuel passage 53a by the injection control valve 20 located at the first position. The piston 60 is biased to the most retracted position. The curved portion of the closing portion 62 abuts on the inclined portion 532 of the check valve chamber 531 to close the upstream third fuel passage 53a. Therefore, the upstream third fuel passage 53a and the check valve chamber 531 are blocked. This state is defined as the last retracted position of the check valve piston 60.
Further, the closing assist piston 30 is urged to the position where the spring 31 is most retracted, and the conical portion of the partition portion 33 closes the downstream third fuel passage 53 b on the base end surface of the needle valve closing chamber 43. ing. This state is the last retracted position of the closing assist piston 30.

In the state where the closing auxiliary piston 30 is located at the last retracted position, the conical portion of the partition portion 33 closes the downstream side third fuel passage 53b, and the downstream side third fuel passage 53b and the closing auxiliary pressure chamber 432 are connected to each other. Blocked.
Further, in the state where the closing assist piston 30 is located at the last retracted position, even if the needle valve 10 is retracted until it is regulated by the movement restricting portion 12, the tip surface of the assist force transmitting portion 32 of the closing assist piston 30 and the needle The movement strokes and lengths of the closing assist piston 30 and the needle valve 10 are set so that a gap is formed between the base end surface of the valve 10 and the valve 10.

Next, the case where the injection control valve 20 moves backward from the first position to the second position will be described.
When the injection control valve 20 moves backward from the first position, the first fuel storage chamber 41 and the upstream third fuel passage 53a communicate with each other, and the fuel in the first fuel storage chamber 41 flows into the upstream third fuel passage 53a. .
The second fuel passage 52 and the upstream third fuel passage 53a communicate with each other, and the fuel in the second fuel passage 52 flows into the upstream third fuel passage 53a.
Then, due to the fuel pressure in the upstream third fuel passage 53a, the check valve piston 60 moves forward against the biasing force of the spring 61, and the closed portion 62 of the check valve piston 60 is inclined in the check valve chamber 531. A gap is formed away from 532.

In this state, the fuel in the upstream third fuel passage 53a flows into the check valve chamber 531, and the fuel in the check valve chamber 531 flows into the fifth fuel passage 55 and the downstream third fuel passage 53b. To do.
At this time, since the check valve chamber 531 is larger than the total volume of the upstream third fuel passage 53a and the downstream third fuel passage 53b, the fuel pressure in the downstream third fuel passage 53b causes the closing auxiliary piston 30 to flow. A time lag occurs after the fuel flows into the check valve chamber 531 until the pressure is sufficient to move forward. At this time, since the inner diameter of the fifth fuel passage 55 is formed to be much smaller than the inner diameter of the downstream third fuel passage 53b, most of the fuel that has flowed into the check valve chamber 531 is formed in the downstream third fuel passage 53b. Flow into.

  When the fuel flowing from the check valve chamber 531 into the downstream third fuel passage 53b reaches a predetermined fuel pressure, the closing auxiliary piston 30 biases the spring 21 by the fuel pressure in the downstream third fuel passage 53b. The front end surface of the auxiliary force transmitting portion 32 comes into contact with the proximal end surface of the needle valve 10.

In this state, the fuel in the downstream third fuel passage 53 b flows into the closing auxiliary pressure chamber 432 of the needle valve closing chamber 43, and the fuel pressure in the fuel reservoir portion 421 of the second fuel storage chamber 42 and the needle valve The fuel pressure in the closed auxiliary pressure chamber 432 of the closed chamber 43 is equal.
Then, the conical portion of the partition portion 33 of the closing assist piston 30 receives the fuel pressure from the closing assist pressure chamber 432 as a pressure receiving portion, so that the needle valve 10 moves forward through the closing assist piston 30. Power is added to.
At the same time, the annular step portion 13 of the needle valve 10 receives the fuel pressure from the fuel reservoir portion 421 as a pressure receiving portion, so that a force is applied to the needle valve 10 in the backward direction.

  Here, the maximum diameter of the partition portion 33 of the closing assist piston 30 is larger than the maximum diameter of the step portion 13 of the needle valve 10, and the pressure receiving area of the partition portion 33 of the close assist piston 30 is the step portion 13 of the needle valve 10. It is larger than the pressure receiving area. Therefore, the force for moving the closing assist piston 30 forward becomes larger than the force for moving the needle valve 10 backward, and the proximal end side of the needle valve 10 is pressed by the distal end surface of the assist force transmitting portion 32 of the closing assist piston 30. The needle valve 10 is advanced.

Next, the state where the injection control valve 20 has returned to the second position will be described.
In this state, since the first fuel passage 51 and the first fuel storage chamber 41 are blocked, the fuel does not flow from the first fuel passage 51 and the first fuel passage 41 and the second fuel passage 52 Fuel gradually decreases. For this reason, since the fuel flowing into the upstream third fuel passage 53a is also reduced, the fuel pressure in the upstream third fuel passage 53a is also gradually reduced.
When the fuel pressure in the upstream third fuel passage 53a becomes smaller than the biasing force of the spring 61 that biases the check valve piston 60, the check valve piston 60 moves to the last retracted position, and the upstream third fuel passage 53a. And the check valve chamber 531 are shut off.

  The upstream third fuel passage 53a and the check valve chamber 531 are shut off, and the fuel in the check valve chamber 531 flows out to the fourth fuel passage 54 through the fifth fuel passage 55, so the downstream third fuel The fuel pressure in the passage 53b also gradually decreases.

At this time, in the needle valve closing chamber 43, fuel flows out from the closing auxiliary pressure chamber 432 to the return pressure chamber 433 through the minute communication path 331, and the fuel pressure in the closing auxiliary pressure chamber 432 gradually decreases. .
The fuel that has flowed into the return pressure chamber 433 is discharged out of the nozzle body 40 through the fourth fuel passage 54.
When the fuel pressure in the closing auxiliary pressure chamber 432 becomes smaller than the biasing force of the spring 31, the closing assist piston 30 moves backward to the last retracted position by the biasing force of the spring 31.
In the process in which the closing auxiliary piston 30 moves backward, the fuel in the closing auxiliary pressure chamber 432 flows back to the check valve chamber 531 through the downstream third fuel passage 53b and the fuel in the downstream third fuel passage 53b. There is a case.
However, the backflowed fuel does not flow out to the upstream third fuel passage 53a because the check valve piston 60 is located at the last retracted position, and passes from the fourth fuel passage 54 through the fifth fuel passage 55 to the nozzle body 40. Leaks out of the water.

Next, the case where the injection control valve 20 moves forward from the second position to the first position will be described.
When the injection control valve 20 quickly advances to the first position, as described above, the first fuel storage chamber 41 and the upstream third fuel passage 53a are shut off, and the first fuel passage 51 and the first fuel storage are closed. The high pressure fuel in the first fuel passage 51 flows into the first fuel storage chamber 41 through communication with the chamber 41.

At this time, when the speed at which the injection control valve 20 moves forward is slow, the high-pressure fuel that has flowed in due to the communication between the first fuel passage 51 and the first fuel storage chamber 41 wraps around the front end surface of the passage closing portion 23. May flow out to the upstream third fuel passage 53a.
The urging force by which the spring 61 of the check valve chamber 531 moves the check valve piston 60 backward is smaller than the fuel pressure flowing in at this time, so that the check valve piston 60 moves forward and the high pressure fuel flows into the check valve chamber 531. Flows into.
The fuel that has flowed into the check valve chamber 531 flows out of the nozzle body 40 from the fourth fuel passage 54 through the fifth fuel passage 55.

When the injection control valve 20 reaches the first position, the fuel in the upstream third fuel passage 53a flows into the check valve chamber 531, so that the fuel pressure in the upstream third fuel passage 53a gradually decreases to a predetermined value. When the pressure decreases, the biasing force of the spring 61 that biases the check valve piston 60 toward the base end surface becomes larger than the fuel pressure, and the spring 61 moves the check valve piston 60 back to the last retracted position.
When the check valve piston 60 is located at the last retracted position, the upstream third fuel passage 53a and the check valve chamber 531 are shut off, so that the fuel pressure in the upstream third fuel passage 53a is controlled by the injection control valve 20. Until the check valve piston 60 is not moved forward until it starts to move back to the second position. Accordingly, the force in the direction of reversing the injection control valve 20 due to the fuel pressure in the upstream third fuel passage 53a is suppressed. For this reason, the driving force of the actuator 70 for advancing the injection control valve 20 can be reduced.
Even when the forward speed of the injection control valve 20 is slow, the time for the injection control valve 20 to move from the second position to the first position is very short. The pressure of the fuel that has flowed out into the third fuel passage 53b is not sufficient to advance the closing auxiliary piston 30, and the closing auxiliary piston 30 is held at the last retracted position.
Even if the closing auxiliary piston 30 moves forward, as described above, the closing auxiliary pressure chamber 432 that flows backward to the check valve chamber 531 when the closing auxiliary piston 30 moves backward thereafter, or the downstream third fuel passage. The fuel of 53b does not flow back into the upstream third fuel passage 53a because the check valve piston 60 is located at the last retracted position. Therefore, the fuel pressure in the upstream third fuel passage 53a pushes the injection control valve 20 in the direction to push it back from the first position, and the injection control valve 20 moves away from the first position. Adverse effects can be suppressed.

Hereinafter, the operation of the fuel injection device 1 will be described with reference to FIGS.
ST1 is an initial state as shown in FIG. That is, fuel is supplied from the fuel supply source to the first fuel passage 51 at a high pressure, and the injection control valve 20 is moved backward by the urging force of the spring 21 to be in the second position. As a result, the passage closing portion 23 of the injection control valve 20 contacts the step portion 411 of the first fuel storage chamber 41, so that the high-pressure fuel in the first fuel passage 51 is separated from the reduced diameter portion 221 of the injection control valve 20. It remains in the gap with the inner peripheral surface of the injection control valve holding portion 44.

  In the check valve chamber 531, the check valve piston 60 is in contact with the inclined portion 532 of the check valve chamber 531 by the biasing force of the spring 61. Thus, the upstream third fuel passage 53a and the check valve chamber 531 are blocked.

  Further, the urging force of the spring 31 causes the needle valve 10 to move forward and seat on the front end side of the second fuel storage chamber 42, and the closing auxiliary piston 30 moves backward and is located at the last retracted position, and the downstream third fuel passage. 53b is closed. As a result, the fuel that has flowed in by the previous injection operation is trapped in the second fuel storage chamber 42, the second fuel passage 52, the first fuel storage chamber 41, and the upstream side third fuel passage 53a at a certain pressure. Yes. Further, the fuel in the check valve chamber 531 is discharged to the outside of the nozzle body 40 through the fourth fuel passage 54 by the fifth fuel passage 55, and the fuel in the return pressure chamber 433 is discharged from the fourth fuel passage. 54 is discharged to the outside of the nozzle body 40.

  In ST2, from this state, as shown in FIG. 2B, when the actuator 70 is driven, the injection control valve 20 moves forward and is positioned at the first position while resisting the biasing force of the spring 21.

Then, the front end surface of the injection control valve main body 22 comes into contact with the front end surface of the first fuel storage chamber 41, and the first fuel storage chamber 41 and the upstream third fuel passage 53a are shut off. Supply of high-pressure fuel to the passage 53a is interrupted.
Further, since the passage closing portion 23 is separated from the step portion 411 of the first fuel storage chamber 41 and a gap is formed between the passage closing portion 23 and the step portion 411 of the first fuel storage chamber 41, the first fuel The high-pressure fuel in the passage 51 passes through the gap between the reduced diameter portion 221 of the injection control valve 20 and the inner peripheral surface of the injection control valve holding portion 44, the first fuel storage chamber 41, and the second fuel passage 52, The fuel flows into the fuel reservoir 421 of the second fuel storage chamber 42. As described above, since the fuel in the fuel reservoir portion 421 is already at a certain pressure, the fuel pressure in the second fuel storage chamber 42 is increased by supplying high-pressure fuel in the first fuel passage 51. To rise.

  In ST3, when the fuel pressure in the fuel reservoir 421 reaches a predetermined pressure, the movement restricting portion 12 of the needle valve 10 is stepped by the fuel pressure in the fuel reservoir 421 as shown in FIG. The needle valve 10 moves backward against the spring 31 until it hits the portion 431. Thereby, the needle valve 10 is separated from the front end side of the second fuel storage chamber 42, and the fuel in the second fuel storage chamber 42 is injected through the injection hole 45.

  In ST4, the driving of the actuator 70 is stopped and the pressing force on the injection control valve 20 is released. Then, as shown in FIG. 3A, the injection control valve 20 moves backward and is positioned at the second position by the biasing force of the spring 21. Then, the passage closing portion 23 comes into contact with the step portion 411 of the first fuel storage chamber 41 and closes the injection control valve holding portion 44. As a result, the first fuel passage 51 and the first fuel storage chamber 41 are blocked, and the first fuel storage chamber 41 and the upstream third fuel passage 53a communicate with each other. Therefore, the fuel in the first fuel storage chamber 41 flows into the upstream third fuel passage 53a through the gap between the front end surface of the injection control valve main body 22 and the front end surface of the first fuel storage chamber 41, and the upstream side. The pressure in the third fuel passage 53a increases.

The portion of the curved portion of the check valve piston 60 exposed to the upstream third fuel passage 53a is pressed by the fuel pressure flowing into the upstream third fuel passage 53a, and the check valve piston 60 moves forward. To do.
Then, the upstream third fuel passage 53 a and the check valve chamber 531 are communicated, and the fuel in the upstream third fuel passage 53 a flows into the check valve chamber 531.

  When flowing into the check valve chamber 531, since the check valve chamber 531 and the downstream third fuel passage 53b are always in communication, the fuel that has flowed into the check valve chamber 531 enters the downstream third fuel passage 53b. It flows in and the fuel pressure in the downstream third fuel passage 53b increases.

  Since the closing auxiliary piston 30 is located at the last retracted position, the downstream side third fuel passage 53b is closed by the partition portion 33. However, due to the fuel pressure flowing into the downstream side third fuel passage 53b, Of the conical portion of the partition portion 33, the portion exposed to the downstream third fuel passage 53b is pressed, and the closing assist piston 30 moves forward.

  In ST5, as shown in FIG. 3B, the closing auxiliary piston 30 has advanced, so that the blocking of the downstream third fuel passage 53b by the partition 33 is released, and the fuel flowing into the downstream third fuel passage 53b is Then, it flows into the closing auxiliary pressure chamber 432 of the needle valve closing chamber 43, and the pressure in the closing auxiliary pressure chamber 432 rises. When the pressure inside the closed auxiliary pressure chamber 432 reaches a predetermined pressure, the entire conical portion of the partition 33 is pressed by the fuel pressure flowing into the closed auxiliary pressure chamber 432, and the closed auxiliary piston 30 moves forward. Then, the distal end surface of the auxiliary force transmitting portion 32 of the closing assist piston 30 comes into contact with the proximal end surface of the needle valve 10.

  In ST6, as shown in FIG. 3C, the fuel in the closing auxiliary pressure chamber 432 presses the partition portion 33. Here, the force applied in the direction in which the closing assist piston 30 moves forward is more than the force applied in the direction in which the fuel in the fuel reservoir portion 421 of the second fuel storage chamber 42 presses the step portion 13 and moves backward to the needle valve 10. Is also big. Accordingly, the closing assist piston 30 moves forward together with the needle valve 10, the needle valve 10 is seated on the distal end side of the second fuel storage chamber 42, and fuel injection from the injection hole 45 is stopped.

In ST7, as shown in FIG. 4, the fuel in the first fuel storage chamber 41 flows into the upstream third fuel passage 53a, and the pressure inside the first fuel storage chamber 41 gradually decreases.
At the same time, since the fuel in the upstream third fuel passage 53a flows into the check valve chamber 531, the pressure in the upstream third fuel passage 53a gradually decreases. When the pressure inside the upstream third fuel passage 53a becomes less than a predetermined pressure, the check valve piston 60 is retracted by the biasing force of the spring 61 and comes into contact with the inclined portion 532 of the check valve chamber 531. .
Accordingly, the upstream third fuel passage 53a and the check valve chamber 531 are blocked.

On the other hand, the fuel inside the closing auxiliary pressure chamber 432 passes through the minute communication path 331 formed in the partition portion 33 and gradually flows out into the return pressure chamber 433, and the fuel flowing out into the return pressure chamber 433 is It is discharged to the outside of the nozzle body 40 through the fourth fuel passage 54.
As a result, the pressure inside the closing auxiliary pressure chamber 432 gradually decreases, and when the pressure inside the closing auxiliary pressure chamber 432 becomes less than a predetermined pressure, the closing auxiliary piston 30 moves backward by the biasing force of the spring 31. To the last retreat position.

At this time, a force for pressing the fuel in the closing auxiliary pressure chamber 432 toward the downstream third fuel passage 53b is generated by the entire conical portion of the partition 33 of the closing auxiliary piston 30, and the downstream third pressure is generated by the force. In some cases, the fuel in the fuel passage 53 b flows back into the check valve chamber 531.
However, since the check valve piston 60 is positioned at the last retracted position, the check valve chamber 531 and the upstream third fuel passage 53a are shut off, so that the fuel in the downstream third fuel passage 53b that has flowed back In addition, the fuel in the check valve chamber 531 does not flow into the upstream third fuel passage 53a.
The fuel in the downstream third fuel passage 53 b that has flowed back and the fuel in the check valve chamber 531 flow out to the fourth fuel passage 54 through the fifth fuel passage 55 and are discharged to the outside of the nozzle body 40. Is done.
As a result, the fuel is trapped in the second fuel storage chamber 42, the second fuel passage 52, the first fuel storage chamber 41, and the upstream side third fuel passage 53a with a certain pressure, and returns to the initial state. .

  A second embodiment will be described with reference to FIG. FIG. 5 is a cross-sectional view of the fuel injection device 1 according to the second embodiment. The second embodiment is different from the first embodiment in the configuration of the third fuel passage 53. The following description will focus on the differences from the first embodiment, and description of the same parts as in the first embodiment will be omitted. In addition, the same code | symbol is attached | subjected in the case similar to 1st Embodiment.

  The third fuel passage 53 is a through hole that directly communicates the first fuel storage chamber 41 and the needle valve closing chamber 43, and the check valve chamber 531 in the first embodiment is not formed in the middle of the through hole. Further, the check valve piston 60 and the spring 61 provided in the check valve chamber 531 in the first embodiment are not provided in the third fuel passage 53 according to the second embodiment.

The fifth fuel passage 55 is a through hole whose one end communicates with the third fuel passage 53 and the other end communicates with the fourth fuel passage 54.
When the closing assist piston 30 moves from the most advanced position to the last retracted position, pressure from the entire conical portion of the partition 33 of the closing assist piston 30 to the proximal side is generated inside the closing assist pressure chamber 432. In some cases, the fuel flows backward to the third fuel passage 53.
Then, the fuel flowing into the third fuel passage 53 from the closed auxiliary pressure chamber 432 flows out to the fourth fuel passage 54 through the fifth fuel passage 55 communicating with the third fuel passage 53, and the nozzle body 40 It is discharged outside.

  The third embodiment will be described with reference to FIG. FIG. 6 is a cross-sectional view of the fuel injection device 1 according to the third embodiment. The third embodiment differs from the second embodiment in the position of the fifth fuel passage 55. The following description will focus on differences from the second embodiment, and description of the same parts as those of the second embodiment will be omitted. In addition, the same code | symbol is attached | subjected in the case similar to 1st Embodiment.

  The fifth fuel passage 55 is a through hole whose one end communicates with the closing auxiliary pressure chamber 432 and the other end communicates with the fourth fuel passage 54. The through hole on the side of the auxiliary closing pressure chamber 432 of the fifth fuel passage 55 is the inner peripheral surface of the auxiliary closing pressure chamber 432, and the stepped portion 431 and the closing portion when the closing auxiliary piston 30 is located at the last retracted position. The auxiliary piston 30 is formed at a position communicating with the space formed by the proximal end of the columnar portion of the partition portion 33 of the auxiliary piston 30.

When the closing assist piston 30 moves from the most advanced position to the last retracted position, pressure from the entire conical portion of the partition 33 of the closing assist piston 30 to the proximal side is generated inside the closing assist pressure chamber 432. In some cases, the fuel flows backward to the third fuel passage 53.
At this time, the fuel which is going to flow backward from the closed auxiliary pressure chamber 432 to the third fuel passage 53 is pressed by the step portion 431 and the inclined surface formed in the substantially conical portion of the partition portion 33, and the fifth fuel passage. To 55. Then, the fuel flows out to the fourth fuel passage 54 through the fifth fuel passage 55 and is discharged to the outside of the nozzle body 40.

According to this embodiment, there are the following effects.
(1) One end side is downstream of the first fuel storage chamber 41 and communicates with the upstream side of the communication portion of the fourth fuel passage 54 in the needle valve closing chamber 43, and the other end side is the fourth fuel passage. A fifth fuel passage 55 communicating with 54 is provided. As a result, the fuel that has flown into the third fuel passage 53 and the needle valve closing chamber 43 is quickly discharged to the fourth fuel passage 54 via the fifth fuel passage 55, and the injection control valve 20 is moved from the second position to the second position. The pressure fluctuation generated in the third fuel passage 53 and the needle valve closing chamber 43 in the process of moving forward to the first position can be suppressed. Then, it is possible to suppress the injection control valve 20 from being pushed back in the backward direction and the needle valve 10 from being loaded in the forward direction.

(2) A closing assist piston 30 that advances and retreats in the needle valve closing chamber 43 is provided, and the closing assist piston 30 is located at the last retracted position so that the third fuel passage 53 and the needle valve closing chamber 43 are shut off, thereby closing assist. When the piston 30 moves forward, the third fuel passage 53 and the needle valve closing chamber 43 communicate with each other. Further, the needle valve closing chamber 43 is divided into a closing assist pressure chamber 432 and a return pressure chamber 433 when the closing assist piston 30 is in the advanced state. One end side of the fifth fuel passage 55 communicates with the closing auxiliary pressure chamber 432.
As a result, in the process in which the injection control valve 20 advances to the first position, the fuel that has flowed into the third fuel passage 53 and the auxiliary closing pressure chamber 432 of the needle valve closing chamber 43 passes through the fifth fuel passage 55 to the nozzle. It can be discharged outside the body 40.

  (3) The third fuel passage 53 is provided with a check valve chamber 531 having a check valve piston 60 as a check valve, and one end side of the fifth fuel passage 55 is seated on the check valve piston 60 (inclined portion 532). Rather than the needle valve closing chamber 43 side. By providing the check valve chamber 531 and the check valve piston 60, the fuel that flows into the check valve chamber 531 from the upstream third fuel passage 53a passes through the upstream third fuel passage 53a and stores the first fuel. Backflow into the chamber 41 can be prevented. Further, since the fifth fuel passage 55 communicates with the downstream side of the seating portion of the check valve piston 60, the fuel that has flowed into the check valve chamber 531 passes through the fifth fuel passage 55 in the nozzle body 40. It can be discharged to the outside.

It should be noted that the present invention is not limited to the above-described embodiment, and modifications, improvements, etc. within a scope that can achieve the object of the present invention are included in the present invention.
For example, in this embodiment, the injection control valve 20 is driven by a piezo-type actuator, but the present invention is not limited to this and may be driven by an electromagnetic or hydraulic actuator.
In the present embodiment, the minute communication path 331 is formed by denting the outer peripheral surface of the partition portion 33 of the closing assist piston 30, but the present invention is not limited to this. It may be provided, or may be formed on the inner peripheral surface of the needle valve closing chamber 43 of the nozzle body 40.

In the present embodiment, the proximal end side of the needle valve 10 is directly pressed by the auxiliary force transmission unit 32 of the closing auxiliary piston 30, but the present invention is not limited to this, and the gap between the closing auxiliary piston 30 and the needle valve 10 is not limited. A member may be provided, and the proximal end side of the needle valve 10 may be pressed through this member.
Further, in the present embodiment, the stepped portion 13 as the pressure receiving portion is formed at one place on the outer peripheral surface of the needle valve main body 11, but the present invention is not limited thereto, and the step is formed at a plurality of locations such as the outer peripheral surface on the distal end side of the needle valve main body 11. A part may be provided.

DESCRIPTION OF SYMBOLS 1 Fuel injection apparatus 10 Needle valve 20 Injection control valve 30 Closure auxiliary piston 31 Spring 40 Nozzle body 41 1st fuel storage chamber 42 2nd fuel storage chamber 43 Needle valve closing chamber 45 Injection hole 51 1st fuel passage 52 2nd fuel passage 53 Third fuel passage 53a Upstream third fuel passage 53b Downstream third fuel passage 54 Fourth fuel passage 55 Fifth fuel passage 60 Check valve piston 61 Spring 432 Closed auxiliary pressure chamber 433 Return pressure chamber 531 Check valve chamber

Claims (3)

A first fuel storage chamber, a second fuel storage chamber, a third fuel storage chamber, and a nozzle body in which nozzle holes extending from the second fuel storage chamber to the outside of the fuel injection device are formed;
A needle valve held in a needle valve holding portion inside the nozzle body;
A needle valve opening means provided on the tip side of the needle valve holding portion inside the nozzle body and having the second fuel storage chamber;
A needle valve closing means provided on the base end side of the needle valve holding portion inside the nozzle body and having the third fuel storage chamber;
An injection control valve held inside the nozzle body and capable of moving back and forth in the first fuel storage chamber,
The nozzle body is
A first fuel passage from a fuel supply source to the first fuel storage chamber;
A second fuel passage from the first fuel storage chamber to the second fuel storage chamber;
A third fuel passage from the first fuel storage chamber to the third fuel storage chamber;
A fourth fuel passage from the third fuel storage chamber to a low pressure portion outside the fuel injection device,
The injection control valve is
By advancing to the first position, the first fuel passage and the first fuel storage chamber communicate with each other, and the first fuel storage chamber and the third fuel passage are shut off,
By retracting to the second position, the first fuel passage and the first fuel storage chamber are shut off, and the first fuel storage chamber and the third fuel passage are communicated with each other.
The needle valve is
By moving forward and seating on the nozzle body, the second fuel storage chamber and the nozzle hole are shut off,
By retreating and separating from the nozzle body, the second fuel storage chamber and the nozzle hole communicate with each other,
The needle valve opening means retracts the needle valve by the fuel pressure in the second fuel storage chamber,
The needle valve closing means advances the needle valve by the fuel pressure in the third fuel storage chamber,
One end side is downstream of the first fuel storage chamber and communicates with the upstream side of the communication portion of the fourth fuel passage in the third fuel storage chamber, and the other end side communicates with the fourth fuel passage. A fuel injection device comprising a fifth fuel passage. The fuel injection device according to claim 1,
The needle valve closing means includes
A closing auxiliary piston provided to be able to advance and retreat in the third fuel storage chamber;
The closing auxiliary piston is
Shutting off the third fuel passage and the third fuel storage chamber at the last retracted position;
The third fuel passage and the third fuel storage chamber communicate with each other by shifting to a forward state,
The third fuel storage chamber is
When the closing auxiliary piston is in the forward movement state, the closing auxiliary piston is divided into a closing auxiliary pressure chamber that communicates with the third fuel passage and a return pressure chamber that communicates with the fourth fuel passage.
The closing auxiliary piston shifts from the advanced state to the last retracted position, and shuts off the third fuel passage and the closing auxiliary pressure chamber, so that the fuel in the first fuel storage chamber is in the third fuel passage. Suppressing the flow of fuel through the third fuel storage chamber through the first fuel storage chamber and preventing the fuel in the first fuel storage chamber from flowing out of the fuel injection device,
One end side of the fifth fuel passage communicates with the closing auxiliary pressure chamber. The fuel injection device according to claim 1,
A reverse flow that allows the third fuel passage to flow from the first fuel storage chamber side to the third fuel storage chamber side and inhibits the flow from the third fuel storage chamber side to the first fuel storage chamber side. With a stop valve,
One end side of the fifth fuel passage communicates with the third fuel storage side rather than the seat portion of the check valve of the third fuel passage.

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