Fuel injector

Abstract

To provide a solenoid valve as a fuel injection valve for preventing a fuel injection amount from deviating from a target value when the resistance of a slide part increases.SOLUTION: A fuel injection valve 90 utilizing the pressure of fuel in a control chamber 10 for driving a nozzle needle 6 includes the nozzle needle 6 for opening / closing a fuel injection hole 3, the control chamber 10 into which fuel flows, and a discharge chamber 30 to be communicated with the control chamber 10 via a communication path 13 during opening of an on-off valve 20, the on-off valve 20 having a valve needle 25 formed with a valve needle hole 26, a pressure pin 61 slidably held in the valve needle hole 26, and an on-off valve seat part 21a for contacting the valve needle 25 to close the communication path 13. The cross section area of a flow path 13b to be formed between the valve needle 25 and the on-off valve seat part 21a while energizing an electromagnet 43 is smaller than the area of an opening part to be formed between the on-off valve seat part 21a side end of a through-hole 13a and the pressure pin 61 during the stop of an internal combustion engine.SELECTED DRAWING: Figure 1

Description

Technical Field

[0004] , ,

[0001] The present invention relates to a fuel injection valve that injects fuel into a combustion chamber of an internal combustion engine.

Background Art

[0002] A fuel injection valve that injects fuel into a combustion chamber such as a diesel engine includes a main body portion having a fuel injection hole for injecting fuel formed at one end, and a nozzle needle that is reciprocally provided inside the main body portion and opens and closes the fuel injection hole. Further, a fuel injection valve having a valve structure that applies the pressure of fuel to the end surface of the nozzle needle on the side opposite to the fuel injection hole side and uses the pressure for driving the nozzle needle has also been proposed (see Patent Document 1).

[0003] Specifically, a fuel injection valve having such a valve structure includes a control chamber formed inside the main body portion so as to face the end surface of the nozzle needle on the side opposite to the fuel injection hole side, into which fuel flows, a discharge chamber formed inside the main body portion, communicating with the control chamber via a communication passage, and into which the fuel flowing into the control chamber flows via the communication passage, and an electromagnetic valve disposed inside the main body portion for opening and closing the communication passage. The electromagnetic valve includes a valve body, an electromagnet that attracts the valve body when energized, and a spring that presses the valve body in a direction away from the electromagnet.

[0004] When the electromagnetic valve is not energized, the valve body seats on the seat portion, blocking the communication between the control chamber and the discharge chamber. When the electromagnetic valve is energized, the valve body is attracted toward the electromagnet and disengages from the seat portion, thereby allowing the control chamber and the discharge chamber to communicate. When the control chamber and the discharge chamber communicate, the fuel in the control chamber flows out to the discharge chamber, and the pressure of the fuel in the control chamber decreases. As a result, the force pressing the nozzle needle toward the fuel injection hole side by the fuel in the control chamber decreases, so that the nozzle needle moves toward the control chamber side (opposite to the fuel injection hole side) and the fuel injection hole is opened, and fuel is injected from the fuel injection hole into the combustion chamber.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2019-7386 [Overview of the project] [Problems that the invention aims to solve]

[0006] The valve body has a through-hole that penetrates in the direction of the valve body's reciprocating motion. A pressure pin is slidably held within the through-hole. During operation of the internal combustion engine, the end of the pressure pin on the passage side is located in a space with high fuel pressure, and high fuel pressure is applied to that end of the pressure pin. On the other hand, the end of the pressure pin opposite the passage side is located in a space with low fuel pressure.

[0007] Therefore, when the internal combustion engine is in operation, the pressure pin rises due to the fuel pressure in the communication passage and contacts the stopper at the top of the pressure pin. On the other hand, when the internal combustion engine is stopped, the pressure pin descends to a position that blocks the communication passage.

[0008] In fuel injection valves with the valve body structure described above, the sliding resistance between the valve body's through-hole and the pressure pin increases due to deterioration over time, which may result in insufficient upward movement of the pressure pin during the next operation of the internal combustion engine, or the pressure pin becoming stuck and unable to move relative to the valve body. If the pressure pin does not rise sufficiently, when the solenoid valve is energized, the fuel flow rate between the passage-side end of the pressure pin and the seat portion may fall below the normal fuel flow rate between the valve body and the seat portion. In such a state, the rate at which the fuel pressure in the control chamber decreases slows down, delaying the start of fuel injection, and as a result, the fuel injection amount decreases compared to the target value.

[0009] Several factors can contribute to an increase in sliding resistance between the valve body's through-hole and the pressure pin. For example, prolonged use can cause wear on the valve body's through-hole and the pressure pin, slightly increasing the gap between the sliding parts. This increase in the gap can alter the angle of the pressure pin compared to when it was new, potentially increasing sliding resistance.

[0010] Furthermore, if the fuel deteriorates due to reasons such as the internal combustion engine not being operated for a long period of time, and the engine is subsequently operated under high load and high rotation speed, the deteriorated fuel can become hot, and deposits may form in the fuel. If the internal combustion engine is stopped in such a state, and deposits are present in the sliding part between the valve body's through-hole and the pressure pin, the sliding resistance between the valve body's through-hole and the pressure pin may increase when the internal combustion engine is operated again.

[0011] Furthermore, although not due to deterioration over time, particulate matter or other foreign matter in the fuel may enter the sliding part between the valve body's through-hole and the pressure pin, increasing the sliding resistance.

[0012] This invention was made against the backdrop of the above-mentioned problems, and aims to provide a fuel injection valve that does not deviate from the target value of the injection amount even when the rise of the pressure pin becomes insufficient due to an increase in sliding resistance between the valve body and the pressure pin. [Means for solving the problem]

[0013] According to the present invention, a fuel injection valve comprises: a main body having a fuel injection hole formed at one end for injecting fuel into the combustion chamber of an internal combustion engine; a nozzle needle provided inside the main body so as to be reciprocally movable and for opening and closing the fuel injection hole; a control chamber formed inside the main body so as to face a first end face of the nozzle needle that is opposite to the end face of the nozzle needle to the fuel injection hole side, into which the fuel flows; a discharge chamber formed inside the main body, communicating with the control chamber via a communication passage, into which the fuel that has flowed into the control chamber flows through the communication passage; and an on-off valve for opening and closing the communication passage, wherein the pressure of the fuel in the control chamber is applied to the first end face of the nozzle needle, and the pressure is used to drive the nozzle needle, wherein the on-off valve is provided inside the main body so as to be reciprocally movable and has a valve needle hole formed therein that penetrates in the direction of the reciprocating motion, and A fuel injection valve is provided, comprising: a pressure pin slidably held within a valve needle hole; and an on-off valve seat portion fixed inside the main body portion and closing the communication passage by contacting the valve needle, wherein the valve needle releases the communication passage by separating from the on-off valve seat portion when the electromagnet is energized, the communication passage comprises a through hole penetrating from the control chamber to the on-off valve seat portion and a flow path formed between the valve needle and the on-off valve seat portion when the electromagnet is energized, the pressure pin forms an opening between the on-off valve seat portion side end of the through hole when the internal combustion engine is stopped, and the cross-sectional area of ​​the flow path formed between the valve needle and the on-off valve seat portion when the electromagnet is energized is smaller than the area of ​​the opening formed between the on-off valve seat portion side end of the through hole and the pressure pin when the internal combustion engine is stopped. [Effects of the Invention]

[0014] According to the fuel injection valve of the present invention, even if the sliding resistance between the valve body and the pressure pin increases in the solenoid valve of the fuel injection valve, it is possible to prevent the fuel injection amount from deviating from the target value. [Brief explanation of the drawing]

[0015] [Figure 1]It is a cross-sectional view schematically showing a fuel injection valve according to a first embodiment of the present invention. [Figure 2] It is an on-off valve in a conventional fuel injection valve, and is a diagram showing a state in which an electromagnet is energized during operation of an internal combustion engine (not shown). [Figure 3] It is an on-off valve in a conventional fuel injection valve, and is a diagram showing a state in which the energization to the electromagnet has ended during operation of an internal combustion engine (not shown). [Figure 4] It is an on-off valve in a conventional fuel injection valve, and is a diagram showing a state in which the operation of an internal combustion engine (not shown) has stopped. [Figure 5] It is an on-off valve in a conventional fuel injection valve, and is a diagram for explaining a state in which the valve needle hole of the valve needle and the pressure pin are stuck. [Figure 6] It is a diagram showing an on-off valve in a state where the operation of an internal combustion engine according to the first embodiment of the present invention has stopped. [Figure 7] It is a diagram showing an on-off valve when the electromagnet is energized in a state where the valve needle and the pressure pin are stuck according to the first embodiment of the present invention. [Figure 8] It is a diagram showing an on-off valve in a state where the operation of an internal combustion engine has stopped according to a second embodiment of the present invention. [Figure 9] It is an enlarged view of the region indicated by Ya in FIG. 8.

Embodiments for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present invention will be described with appropriate reference to the drawings. Note that the members, arrangements, etc. described below do not limit the present invention, and various modifications can be made within the scope of the gist of the present invention. Also, in each figure, those with the same reference numerals indicate the same elements, and the description is appropriately omitted. Also, in each figure, the illustration of detailed parts is appropriately simplified or omitted. Also, duplicate descriptions are appropriately simplified or omitted.

[0017] (First Embodiment) A first embodiment of the present invention will be described with reference to the drawings as appropriate. FIG. 1 is a cross-sectional view schematically showing a fuel injection valve according to the first embodiment of the present invention. The fuel injection valve 90 includes a main body portion 1 having a fuel injection hole 3 for injecting fuel formed at one end. In the present embodiment, the main body portion 1 is composed of a nozzle main body 2, a union nut 4, and a closing plate 5. Note that these components constituting the main body portion 1 are merely examples. Depending on the design of the fuel injection valve 90, the number of divisions of the main body portion 1, that is, the number of components constituting the main body portion 1, can be arbitrarily changed. Also, for the fuel injection valve 90 in the present description, unless otherwise specified, the side of the fuel injection hole 3 in FIG. 1 is taken as the lower side, and the opposite side, that is, the side of the closing plate 5 is taken as the upper side.

[0018] The nozzle main body 2 constitutes the lower part of the main body portion 1, and the union nut 4 constitutes the upper part of the main body portion 1, and both are formed in a cylindrical shape. The nozzle main body 2 is airtightly fixed to the lower end of the union nut 4, for example, by press-fitting or the like. Also, the upper end of the union nut 4 is airtightly closed by the closing plate 5.

[0019] A high-pressure chamber 52 is formed inside the nozzle main body 2. High-pressure fuel is supplied to the high-pressure chamber 52 from the outside (for example, a common rail, a fuel pump, etc.) through a fuel inlet 51 formed in the nozzle main body 2 and the union nut 4. A fuel injection hole 3 is formed at the lower end of the nozzle main body 2. Through the fuel injection hole 3, the high-pressure fuel in the high-pressure chamber 52 is injected into a combustion chamber of an internal combustion engine (not shown).

[0020] The upper end of the high-pressure chamber 52 (i.e., the end opposite to the fuel injection hole 3) is defined by a valve plate 21. The valve plate 21 is sandwiched between a fixing ring 4a attached to the inner circumferential surface of a union nut 4 and the nozzle body 2, and is fixed inside the main body 1, hermetically closing the high-pressure chamber 52. A cylindrical projection 14 surrounding the control chamber 10 is formed on the wall portion of the valve plate 21 that forms the surface facing the high-pressure chamber 52. The end of the cylindrical projection 14 facing the fuel injection hole 3 is closed by a wall 11. The wall 11 also has a nozzle needle opening 11a into which the nozzle needle 6, described later, is inserted. Furthermore, a through hole 12 is formed in the cylindrical projection 14 surrounding the control chamber 10, connecting the control chamber 10 and the high-pressure chamber 52. The through hole 12 has an upstream orifice 12a formed as a region with a narrowed flow path cross-sectional area. In other words, the high-pressure fuel in the high-pressure chamber 52 flows into the control chamber 10 via the upstream orifice 12a.

[0021] Inside the nozzle body 2, a nozzle needle 6 is provided so as to be able to reciprocate (move up and down in Figure 1) along the axis of the high-pressure chamber 52. This nozzle needle 6 opens and closes the fuel injection hole 3. The nozzle needle 6 has a first portion 6a near the control chamber 10 and a second portion 6b near the fuel injection hole 3. The nozzle needle 6 may be constructed as a single unit, or it may be composed of multiple components that are operationally connected to each other. The first portion 6a of the nozzle needle 6 has a first end face 6aa as the end face on the valve plate 21 side.

[0022] The first portion 6a of the nozzle needle 6 is inserted into the nozzle needle opening 11a formed in the wall 11 and protrudes into the control chamber 10. That is, the control chamber 10 applies downward fuel pressure to the first end face 6aa of the nozzle needle 6.

[0023] Furthermore, a flange-shaped projection 8 is formed on the outer surface of the nozzle needle 6 at a position below the wall 11. A spring 9 is provided between the projection 8 and the wall 11, biasing the nozzle needle 6 toward the fuel injection hole 3, so that a downward force (i.e., toward the fuel injection hole 3) is applied to the nozzle needle 6. In addition, a stepped portion 7 is formed on the second portion 6b of the nozzle needle 6. The pressure of the high-pressure fuel in the high-pressure chamber 52 acts on the stepped portion 7, so that an upward force (i.e., toward the fuel injection hole 3) is applied to the nozzle needle 6. A seat portion 18 is formed in the part of the nozzle body 2 that connects to the fuel injection hole 3, and when the nozzle needle 6 seats against the seat portion 18, the fuel injection hole 3 is closed, and the high-pressure fuel in the high-pressure chamber 52 is not injected from the fuel injection hole 3. On the other hand, as the nozzle needle 6 lifts away from the seat portion 18, the fuel injection hole 3 opens, and the high-pressure fuel in the high-pressure chamber 52 is injected from the fuel injection hole 3.

[0024] On the side of the valve plate 21 opposite to the control chamber 10, i.e., the upper end face of the valve plate 21, a discharge chamber 30 is formed, surrounded by a cylindrical wall 31 and a wall 33 that closes the upper end of the wall 31. The cylindrical wall 31 and the wall 33 that closes the upper end of the wall 31 may be formed as a single unit. The cylindrical wall 31 is fixed to the upper end face of the valve plate 21 by welding or other appropriate method. The discharge chamber 30 is formed inside the main body 1 and communicates with the control chamber 10 via a communication passage 13, and fuel that has flowed into the control chamber 10 flows in through the communication passage 13. The valve plate 21 also has a through hole 13a which is part of the configuration of the communication passage 13 that connects the control chamber 10 and the discharge chamber 30. The through hole 13a has a downstream orifice 13c which is formed as a region with a narrowed flow path cross-sectional area. A valve needle 25 is positioned on the discharge chamber 30 side of the valve plate 21. This valve needle 25, together with the valve plate 21, becomes a component of the on / off valve 20.

[0025] The valve needle 25 is reciprocally movable (up and down in Figure 1) in the direction toward the valve plate 21 and away from the valve plate 21. The valve needle 25 is guided to an opening 33a formed in the wall 33 that constitutes the discharge chamber 30. The valve needle 25 is formed in a substantially cylindrical shape, and a valve needle hole 26 is formed inside the valve needle 25 that penetrates in the direction of reciprocating motion (up and down in Figure 1) along the vertical axis of the fuel injection valve 90. A pressure pin 61 is slidably held inside the valve needle hole 26. The upper end face of the pressure pin 61 rises due to the fuel pressure in the through hole 13a when an internal combustion engine (not shown) is in operation, and contacts the lower end face of the stopper 15 located below the closing plate 5. The pressure pin 61 extends through the center of the valve needle hole 26, the armature plate hole 41a (described later), the spring 42, and the electromagnet 43. The valve needle 25 reciprocates vertically along the opening 33a formed in the wall 33 that constitutes the discharge chamber 30, due to the biasing force of the spring 42 on the armature plate 41 (described later) and the magnetic force of the electromagnet. That is, the on / off valve 20 includes a valve needle 25, a pressure pin 61, a valve plate 21, an armature plate 41, a spring 42, and an electromagnet 43.

[0026] When the tip portion 25a of the valve needle 25, which is the end face of the valve needle 25 on the valve plate 21 side, is in contact with the on-off valve seat portion 21a formed on the outer circumference of the opening of the through hole 13a in the valve plate 21, that is, when the on-off valve 20 is closed, it closes the flow path 13b (hereinafter also referred to as the first opening) between the tip portion 25a of the valve needle 25 and the on-off valve seat portion 21a. When the tip portion 25a of the valve needle 25 on the valve plate 21 side is away from the on-off valve seat portion 21a formed on the outer circumference of the opening of the through hole 13a in the valve plate 21, that is, when the on-off valve 20 is open, it opens the flow path 13b (first opening) between the tip portion 25a of the valve needle 25 and the on-off valve seat portion 21a. In other words, the communication passage 13 connecting the control chamber 10 and the discharge chamber 30 is composed of a through hole 13a formed in the valve plate 21 and a flow path 13b (first opening) between the valve plate 21 and the valve needle 25. The on / off valve 20 opens and closes the communication passage 13.

[0027] As described above, when the on-off valve 20 opens, the control chamber 10 and the discharge chamber 30 are connected via the communication passage 13 (through hole 13a, flow path 13b). Therefore, the fuel in the control chamber 10 flows into the discharge chamber 30 through the communication passage 13. Here, the flow path cross-sectional area of ​​the downstream orifice 13c formed in the through hole 13a is larger than the flow path cross-sectional area of ​​the upstream orifice 12a. Also, when the on-off valve 20 is open, the flow path cross-sectional area of ​​the flow path 13b (first opening) between the tip 25a of the valve needle 25 and the on-off valve seat 21a is configured to be larger than the flow path cross-sectional area of ​​the downstream orifice 13c. Therefore, when the on-off valve 20 is opened, the amount of fuel flowing out of the control chamber 10 to the discharge chamber 30 is greater than the amount of fuel flowing in from the high-pressure chamber 52 to the control chamber 10. Therefore, when the shut-off valve 20 is opened, the fuel pressure in the control chamber 10 becomes lower than the fuel pressure in the high-pressure chamber 52.

[0028] Two outlet holes 32 are formed in the wall 31 surrounding the discharge chamber 30. These outlet holes 32 are through-holes that connect the discharge chamber 30 to a low-pressure chamber 53 formed above the valve plate 21 within the union nut 4. The low-pressure chamber 53 is in communication with a fuel outlet 54 that discharges the fuel supplied to the fuel injection valve 90 to the outside. Therefore, high fuel pressure is not formed within the low-pressure chamber 53.

[0029] The valve needle 25 extends into the low-pressure chamber 53 through an opening 33a formed in the wall 33 that surrounds the upper part of the discharge chamber 30. In other words, the upper end of the valve needle 25 (the end opposite to the valve plate 21) protrudes above the wall 33. An armature plate 41, formed in the shape of a disc, is provided at this upper end of the valve needle 25. The armature plate 41 extends in the low-pressure chamber 53 perpendicular to the vertical direction of the fuel injection valve 90. The armature plate 41 has an armature plate hole 41a that penetrates in the direction of reciprocating motion (up and down in Figure 1) along the vertical axis of the fuel injection valve 90. A pressure pin 61 is inserted into this armature plate hole 41a. The armature plate 41 and the valve needle 25 may be formed as a single unit. When the armature plate 41 and the valve needle 25 are formed as a single unit, the armature plate hole 41a also becomes part of the valve needle hole 26.

[0030] A spring 42 is positioned between the armature plate 41 and the stopper 15. The spring 42 biases the armature plate 41 toward the valve plate 21 so that the valve needle 25 is pressed against the valve plate 21, closing the space between them.

[0031] An electromagnet 43 is provided between the armature plate 41 and the stopper 15. When the electromagnet 43 is activated (power is supplied to the electromagnet 43), the armature plate 41 moves upward against the force of the spring 42. In other words, the valve needle 25 attached to the armature plate 41 moves in the direction that opens the on-off valve 20. That is, the on-off valve 20 is opened by the activation of the electromagnet 43. When the on-off valve 20 is opened, the fuel in the control chamber 10 flows into the discharge chamber 30 as described above, and from the discharge chamber 30, it flows further through the outlet hole 32 to the low-pressure chamber 53 and the fuel outlet 54. The space between the armature plate 41 and the electromagnet 43 is part of the low-pressure chamber 53 and is a space with low fuel pressure.

[0032] When fuel flows out of the control chamber 10, the fuel pressure inside the control chamber 10 decreases. The upward force acting on the stepped portion 7 of the nozzle needle 6, caused by the fuel pressure in the high-pressure chamber 52, exceeds the downward force acting on the nozzle needle 6 caused by the fuel pressure in the control chamber 10 and the spring 9. As a result, the nozzle needle 6 moves upward and opens the fuel injection hole 3. This causes the fuel in the high-pressure chamber 52 to be injected through the fuel injection hole 3 into the combustion chamber of an internal combustion engine (not shown).

[0033] To terminate fuel injection from the fuel injection port 3, the power supply to the electromagnet 43 is stopped. This causes the armature plate 41 to be pressed down to the closed position by the spring 42. The valve needle 25 also moves downward along with the armature plate 41 and comes into contact with the valve plate 21. In other words, the on-off valve 20 closes. When the on-off valve 20 closes, the fuel in the control chamber 10 cannot flow out of the control chamber 10 to the discharge chamber 30. As a result, the fuel pressure in the control chamber 10 increases. The increased fuel pressure in the control chamber 10, along with the force of the spring 9, applies a downward force to the first end face 6aa of the nozzle needle 6, pressing the nozzle needle 6 down to the closed position. This causes the nozzle needle 6 to descend, and the lower end face 6ba of the second portion 6b of the nozzle needle 6 closes the fuel injection port 3. As a result, no further fuel is injected from the high-pressure chamber through the fuel injection port 3.

[0034] Next, the details of the on-off valve 20 will be explained. First, the on-off valve 20 in the conventional fuel injection valve 190 will be explained with reference to Figures 2 to 5. Figures 2 to 5 are enlarged views of the area indicated by Y in Figure 1, and correspond to the conventional fuel injection valve 190. In the conventional fuel injection valve 190, the parts not shown in Figures 2 to 5 have the same configuration as in Figure 1.

[0035] Figure 2 shows the on-off valve 20 in a conventional fuel injection valve 190, in a state where an internal combustion engine (not shown) is in operation and the electromagnet 43 is energized. In the state shown in Figure 2, when the electromagnet 43 is energized, the valve needle 25 and armature plate 41 rise, and the fuel in the control chamber 10 flows out to the discharge chamber 30. As a result the fuel pressure in the control chamber 10 decreases, the nozzle needle 6 rises, and fuel is injected.

[0036] Furthermore, the pressure pin 61 rises due to the fuel pressure received from the control room 10, and the upper end face of the pressure pin 61 comes into contact with the stopper 15 located below the closing plate 5. At this time, a portion of the lower end of the pressure pin 61 remains inside the through hole 13a, and the pressure pin 61 has not completely come out of the through hole 13a.

[0037] In the state shown in Figure 2, the dimensions of each part are set such that the cross-sectional area of ​​the flow path 13b (the flow path formed in the region indicated by B in Figure 2, the first opening) formed by the tip 25a of the valve needle 25 and the on-off valve seat portion 21a, i.e., the opening area Sseat of the first opening, is smaller than the cross-sectional area of ​​the opening formed between the on-off valve seat portion 21a side end of the through hole 13a and the pressure pin 61 (the flow path formed in the region indicated by C in Figure 2, hereinafter also referred to as the second opening), i.e., the opening area Sbolt of the second opening. At this time, if the flow rate of fuel per unit time passing through the first opening is Qseat and the flow rate of fuel per unit time passing through the second opening is Qbolt, then Qseat <Qboltとなる。

[0038] Furthermore, in the state shown in Figure 2, the dimensions of each part are set such that the cross-sectional area of ​​the downstream orifice 13c (the flow path in the region indicated by A in Figure 2, hereinafter also referred to as the third opening), i.e., the opening area Sa of the third opening, is smaller than the cross-sectional area of ​​the flow path 13b formed by the tip 25a of the valve needle 25 and the on / off valve seat portion 21a, i.e., the opening area Sseat of the first opening. At this time, if the flow rate of fuel passing through the third opening per unit time is Qa, then Qa <Qseatとなる。

[0039] That is, the relationship is Qa < Qseat < Qbolt.

[0040] FIG. 3 shows the on-off valve 20 in the conventional fuel injection valve 190, and is a diagram showing a state in which energization to the electromagnet 43 has ended during the operation of an internal combustion engine (not shown). Since the electromagnet 43 is not energized, the tip portion 25a of the valve needle 25 is seated on the on-off valve seat portion 21a. On the other hand, since the pressure pin 61 receives the pressure of the fuel from the control chamber 10 side, it remains raised. That is, the pressure pin 61 is always in a raised state during the operation of an internal combustion engine (not shown) in which the fuel injection valve 190 is mounted.

[0041] FIG. 4 shows the on-off valve 20 in the conventional fuel injection valve 190, and is a diagram showing a state in which the operation of an internal combustion engine (not shown) has been stopped. Since the operation of the internal combustion engine has stopped, the electromagnet 43 is not energized, and the tip portion 25a of the valve needle 25 is seated on the on-off valve seat portion 21a. Further, since the internal combustion engine (not shown) has stopped, the pressure of the fuel in the control chamber 10 has also decreased to approximately the same level as the pressure of the fuel in the low-pressure chamber 53, and the pressure pin 61 has also descended. At this time, a stepped portion 61b formed in the vicinity of the lower end portion of the pressure pin 61 and having a reduced diameter as it goes toward the control chamber 10 side is in contact with the on-off valve seat portion 21a side end portion of the through hole 13a.

[0042] FIG. 5 shows the on-off valve 20 in the conventional fuel injection valve 190, and is a diagram for explaining a state in which the valve needle hole 26 of the valve needle 25 and the pressure pin 61 are stuck. Such a state occurs due to an increase in the sliding resistance in the sliding portion when the inclination of the pressure pin in the sliding portion changes compared to when it is new due to a change in the gap of the sliding portion due to wear, when deposits are present in the fuel, or when fine particles, foreign substances, etc. in the fuel enter the sliding portion.

[0043] FIG. 5 shows a state in which during the operation of an internal combustion engine, when the pressure pin 61 cannot move relative to the valve needle hole 26 (sticking state), the electromagnet 43 is energized. When the pressure pin 61 sticks to the valve needle hole 26 and the electromagnet 43 is energized, the pressure pin 61 rises together with the valve needle 25, but it can only rise by the stroke amount of the valve needle 25.

[0044] At this time, the opening area Sbolt of the second opening formed between the end portion on the opening and closing valve seat portion 21a side of the through hole 13a and the pressure pin 61 is smaller than the opening area Sseat of the first opening formed by the tip portion 25a of the valve needle 25 and the opening and closing valve seat portion 21a, or the opening area Sa of the third opening formed as the downstream orifice 13c. At this time, the flow rates Qseat, Qbolt, and Qa of the fuel passing through the first opening, the second opening, and the third opening per unit time are in the relationship of Qa < Qbolt < Qseat, or Qbolt < Qa < Qseat.

[0045] When such a state occurs, when the opening and closing valve 20 is opened by energizing the electromagnet 43, the resistance when the fuel passes through the second opening formed between the end portion on the opening and closing valve seat portion 21a side of the through hole 13a and the pressure pin 61 increases, and the rate of decrease in the fuel pressure in the control chamber 10 slows down. As a result, the rise of the nozzle needle 6 is delayed, and the injection amount decreases with respect to the target value.

[0046] Next, the opening and closing valve 20 in the first embodiment of the present invention will be described with reference to FIGS. 6 and 7. FIG. 6 is a diagram showing the opening and closing valve 20 in a state where the operation of an internal combustion engine (not shown) according to the present embodiment has stopped. [[ID=第十五]]

[0047] In this embodiment, the valve needle 25 has a small-diameter portion 26a formed near the lower end of the valve needle hole 26 as a reduced-diameter portion extending over a predetermined length. The pressure pin 61 also has a stepped portion 61a formed near its lower end that decreases in diameter as it approaches the control chamber 10. Therefore, when the internal combustion engine stops, the pressure pin 61 descends, and the stepped portion 61a of the pressure pin 61 seats on the upper side of the small-diameter portion 26a. In other words, when the internal combustion engine stops, the stepped portion 61a does not seat on the end of the through hole 13a on the side of the on-off valve seat portion 21a. To put it another way, when the internal combustion engine stops, unlike in the conventional design, a gap exists between the end of the through hole 13a on the side of the on-off valve seat portion 21a and the pressure pin 61. At this time, a portion of the lower side of the pressure pin 61 is inside the through hole 13a.

[0048] At this time, the dimensions of each part are set such that the opening area Sseat of the first opening (the flow path formed in the region indicated by B in Figure 7) when the electromagnet 43 is energized during the operation of the internal combustion engine is smaller than the opening area Sbolt of the second opening (the flow path formed in the region indicated by C in Figure 6) in Figure 6 (when the internal combustion engine is stopped).

[0049] Figure 7 shows the on-off valve 20 when the valve needle 25 and pressure pin 61 are stuck together, and the electromagnet 43 is energized during the operation of an internal combustion engine (not shown).

[0050] At this time, the pressure pin 61 is rising together with the valve needle 25, but the relative positional relationship between the valve needle 25 and the pressure pin 61 remains unchanged compared to Figure 6. In other words, in Figure 7, the pressure pin 61 is not moving upward within the valve needle hole 26 despite receiving fuel pressure from below.

[0051] In the state shown in Figure 7, the pressure pin 61 has risen by the amount of the valve needle 25 lift compared to the state shown in Figure 6. Therefore, the opening area Sbolt of the second opening in Figure 7 is equal to or slightly larger than the opening area Sbolt of the second opening in Figure 6.

[0052] Also, as described above, when the electromagnet 43 is energized during the operation of the internal combustion engine, the opening area Sseat of the first opening is smaller than the opening area Sbolt of the second opening when the internal combustion engine is stopped (when the pressure pin descends). Therefore, when the electromagnet 43 is energized during the operation of the internal combustion engine, Sseat < Sbolt always holds.

[0053] Also, as in the prior art, since Sa < Sseat, during the operation of the internal combustion engine, the relationship among the opening area Sseat of the first opening, the opening area Sbolt of the second opening, and the opening area Sa of the third opening is always Sa < Sseat < Sbolt. That is, the flow rates Qseat, Qbolt, and Qa of the fuel passing through the first opening, the second opening, and the third opening per unit time are always Qa < Qseat < Qbolt.

[0054] Therefore, according to the present invention, even when the valve needle hole 26 of the valve needle 25 and the pressure pin 61 are stuck, the fuel injection amount does not decrease with respect to the target value. Also, even when the valve needle hole 26 of the valve needle 25 and the pressure pin 61 are not stuck but the ascending amount of the pressure pin 61 is smaller than normal due to an increase in sliding resistance, Qbolt is equal to or larger than that in the stuck state, so the relationship of Qa < Qseat < Qbolt is maintained even in this case.

[0055] (Second Embodiment) Next, the fuel injection valve 90 in the second embodiment of the present invention will be described with reference to FIGS. 8 and 9. FIG. 8 is a view showing the on - off valve 20 in a state where the operation of an internal combustion engine (not shown) according to the second embodiment of the present invention has stopped.

[0056] The valve needle 25 in the present embodiment has the same shape as the valve needle 25 in the conventional fuel injection valve 190. That is, a small - diameter portion 26a is not formed in the valve needle hole 26. Thus, in FIG. 8, the pressure pin 61 descends, and the stepped portion 61a is seated on the end portion on the on - off valve seat portion 21a side of the through - hole 13a.

[0057] Figure 9 is an enlarged view of the region indicated by Ya in Figure 8, and shows the area near the lower end of the pressure pin 61. As shown in Figure 9, the pressure pin 61 according to this embodiment has multiple vertical grooves 61d formed in the stepped portion 61a, which is the part that sits on the end of the through hole 13a on the side of the on-off valve seat portion 21a when it is lowered.

[0058] In other words, in this embodiment, the groove 61d forms an opening between the end of the through hole 13a on the side of the on-off valve seat portion 21a and the pressure pin 61 when the pressure pin 61 is seated on the end of the through hole 13a on the side of the on-off valve seat portion 21a. Therefore, in this embodiment, this opening becomes the second opening.

[0059] In this embodiment as well, the dimensions of each part are set such that the opening area Sseat of the first opening when the electromagnet 43 is energized during the operation of the internal combustion engine is smaller than the opening area Sbolt of the second opening in Figure 8 (when the internal combustion engine is stopped). Furthermore, the dimensions and number of grooves 61d can be arbitrarily set as long as the relationship between Sseat and Sbolt is maintained.

[0060] Furthermore, even if the pressure pin 61 and the valve needle 25 stick together, when the electromagnet 43 is energized during the operation of the internal combustion engine, the pressure pin 61 rises by the amount of the valve needle 25's lift, so the Sbolt becomes slightly larger than in the state shown in Figure 8.

[0061] As described above, when the electromagnet 43 is energized during the operation of the internal combustion engine, the opening area Sseat of the first opening is smaller than the opening area Sbolt of the second opening when the internal combustion engine is stopped (when the pressure pin is lowered). Therefore, when the electromagnet 43 is energized during the operation of the internal combustion engine, Sseat is always smaller. <Sboltとなる。

[0062] Also, similar to the first embodiment, since Sa < Sseat, during the operation of the internal combustion engine, the relationship between the opening area Sseat of the first opening, the opening area Sbolt of the second opening, and the opening area Sa of the third opening is always Sa < Sseat < Sbolt. That is, the flow rates Qseat, Qbolt, and Qa of the fuel passing through the first opening, the second opening, and the third opening per unit time are always Qa < Qseat < Qbolt.

[0063] Therefore, also in this embodiment, similar to the first embodiment, even when the pressure pin 61 and the valve needle 25 are stuck, the fuel injection amount is not affected. Further, even when the valve needle hole 26 of the valve needle 25 and the pressure pin 61 are not stuck, but the rising amount of the pressure pin 61 is smaller than normal due to an increase in sliding resistance, compared to the stuck state, Qbolt becomes larger. Therefore, even in this case, the relationship Qa < Qseat < Qbolt is maintained.

[0064] As described above, according to the present invention, in the solenoid valve of the fuel injection valve, even when the sliding resistance between the valve needle hole 26 of the valve needle 25 and the pressure pin 61 increases and the rise of the pressure pin 61 becomes insufficient, it is possible to prevent the fuel injection amount from deviating from the target value.

Explanation of Reference Numerals

[0065] 1: Main body part, 3: Fuel injection hole, 6: Nozzle needle, 6aa: First end face, 10: Control chamber, 13: Communication passage, 13a: Through hole, 13b: Flow path, 13c: Orifice, 20: On-off valve, 21a: On-off valve seat part, 25 Valve needle, 26: Valve needle hole, 26a: Small diameter part, 43: Electromagnet, 61: Pressure pin, 61d: Groove, 90: Fuel injection valve

Claims

1. A main body (1) having a fuel injection port (3) formed at one end for injecting fuel into the combustion chamber of an internal combustion engine, A nozzle needle (6) is provided inside the main body (1) so as to be able to reciprocate, and opens and closes the fuel injection hole (3), A control chamber (10) into which the fuel flows is formed inside the main body (1) so as to face the first end face (6aa), which is the end face of the nozzle needle (6) opposite to the fuel injection hole (3), A discharge chamber (30) is formed inside the main body and communicates with the control chamber (10) via a communication passage (13), and the fuel that has flowed into the control chamber (10) flows into the discharge chamber (30) via the communication passage (13), A shut-off valve (20) opens and closes the aforementioned communication passage (13), Equipped with, A fuel injection valve (90) that applies the pressure of the fuel in the control chamber (10) to the first end face (6aa) of the nozzle needle (6), and uses that pressure to drive the nozzle needle (6), The aforementioned on-off valve (20) is A valve needle (25) is provided inside the main body (1) so as to be able to reciprocate, and a valve needle hole (26) is formed therein that penetrates in the direction of the reciprocating motion, A pressure pin (61) is slidably held within the valve needle hole (26), A valve seat portion (21a) is fixed inside the main body portion (1) and closes the communication passage (13) by contacting the valve needle (25), It has, The valve needle (25) opens the communication passage (13) by separating from the on / off valve seat portion (21a) when the electromagnet (43) is energized. The communication passage (13) has a through hole (13a) that penetrates from the control chamber (10) to the on-off valve seat portion (21a), and a flow path (13b) that is formed between the valve needle (25) and the on-off valve seat portion (21a) when the electromagnet (43) is energized. The pressure pin (61) forms an opening between the through hole (13a) and the end of the on / off valve seat portion (21a) when the internal combustion engine is stopped. When the electromagnet (43) is energized, the cross-sectional area of ​​the flow path (13b) formed between the valve needle (25) and the on-off valve seat portion (21a) is smaller than the area of ​​the opening formed between the on-off valve seat portion (21a) side end of the through hole (13a) and the pressure pin (61) when the internal combustion engine is stopped. Fuel injector (90).

2. The fuel injection valve (90) according to claim 1, wherein the through hole (13a) is provided with an orifice (13c), and the flow path cross-sectional area of ​​the orifice (13c) is smaller than the cross-sectional area of ​​the flow path (13b) formed between the valve needle (25) and the on / off valve seat portion (21a) when the electromagnet (43) is energized.

3. The fuel injection valve (90) according to claim 1, wherein the opening formed between the end of the through hole (13a) on the side of the on-off valve seat portion (21a) and the pressure pin (61) when the internal combustion engine is stopped is formed when the pressure pin (61) is seated on a small-diameter portion (26a) in the valve needle hole (26) which has an inner diameter smaller than the region in which the pressure pin (61) slides.

4. The fuel injector (90) according to claim 1, wherein the opening formed between the end of the through hole (13a) on the on-off valve seat portion (21a) side and the pressure pin (61) when the internal combustion engine is stopped is formed by a groove (61d) formed on the surface of the pressure pin (61) that seats on the end of the through hole (13a) on the on-off valve seat portion (21a) side.

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