JP2018178947A - Fuel injection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection device capable of suppressing corrosion of a seat portion in comparison with a conventional one, even when a pressure of a fuel supplied to the fuel injection device becomes high.SOLUTION: A fuel injection device includes a control chamber 10 which is formed to be opposed to an upper end portion 6a of a nozzle needle 6 and to which a fuel flows, a discharge chamber 30 which is communicated to the control chamber 10 through a communication passage 13 and in which the fuel flowing into the control chamber 10 flows through the communication passage 13, and an opening/closing valve 20 for opening and closing the communication passage 13. The opening/closing valve 20 includes a valve plate 21 having a seat portion 22 with a flat face, and a valve needle 25 having a projecting portion 27 coming into contact with the seat portion 22 when the opening/closing valve 20 is in a closed state. The valve plate 21 has a step portion 23 projecting to a valve needle 25 side with respect to the seat portion 22, at a position on an upstream side with respect to the seat portion 22 in a flowing direction of the fuel flowing through the communication passage 13.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a fuel injection device (injector) that injects fuel into a combustion chamber of an engine.

  A fuel injection device for injecting fuel into a combustion chamber of a diesel engine or the like is provided with a main body portion having a fuel injection hole for injecting fuel at one end, and is reciprocably provided in the main body portion to open and close the fuel injection hole. And a nozzle needle. In addition, in the conventional fuel injection device, the pressure of the fuel is applied to the first end, which is the end opposite to the fuel injection hole side in the nozzle needle, and the balance valve is used to drive the nozzle needle. A fuel injection device having a structure has also been proposed (see Patent Document 1).

  Specifically, the fuel injection device having such a balance valve structure is formed inside the main body so as to face the first end of the nozzle needle, and the control chamber through which the fuel flows, and the control chamber via the communication passage. And a discharge chamber through which the fuel flowing into the control chamber flows in via the communication passage, and an on-off valve for opening and closing the communication passage. Therefore, by opening the communication passage by the on-off valve, the fuel in the control chamber flows out to the discharge chamber, and the pressure of the fuel in the control chamber is reduced. As a result, the fuel in the control chamber reduces the force of pressing the nozzle needle to the fuel injection hole side, so the nozzle needle moves to the control chamber side (opposite to the fuel injection hole) and the fuel injection hole is opened. The fuel is injected from the fuel injection holes into the combustion chamber.

JP 2012-526227 gazette

  The on-off valve for opening and closing the communication passage communicating the control chamber and the discharge chamber includes a first valve body and a second valve body which move relative to each other. The first valve body has a flat sheet portion. Moreover, the 2nd valve body has a protrusion part in the position facing the sheet | seat part of a 1st valve body. Therefore, when the projection of the second valve body contacts the seat portion of the first valve body, the flow path between the first valve body and the second valve body is closed. That is, when the protruding portion of the second valve body contacts the seat portion of the first valve body, the on-off valve is closed, and the communication passage connecting the control chamber and the discharge chamber is closed. Further, in a state where the protruding portion of the second valve body is not in contact with the seat portion of the first valve body, the flow path between the first valve body and the second valve body is in an open state. That is, the on-off valve is opened, and the communication passage connecting the control chamber and the discharge chamber is opened. Then, when the on-off valve is opened, the fuel in the control chamber flows out to the discharge chamber through the flow path between the first valve body and the second valve body, and the pressure of the fuel in the control chamber decreases. The fuel injection hole is opened by the operation of the nozzle needle as described above.

  That is, when the on-off valve is opened and the flow path formed between the first valve body and the second valve body is observed along the fuel flow direction, the flow path of the second valve body The channel cross-sectional area is reduced to the tip position. For this reason, the fuel flowing through the flow path between the first valve body and the second valve body collides with the seat portion of the first valve body disposed at the position facing the projecting portion of the second valve body Will flow to Therefore, when the foreign matter is mixed in the fuel, when the fuel flows through the flow path between the first valve body and the second valve body, the foreign matter mixed in the fuel is also the first valve body. It collides with the seat section. The amount of foreign matter in the fuel varies depending on the degree of fuel purification and the environment in which the fuel injection device, that is, the engine is used.

  Here, in recent years, the pressure of the fuel supplied to the fuel injection device has become high. Then, further increase in the pressure of fuel supplied to the fuel injection device is expected in the future. As described above, when the pressure of the fuel supplied to the fuel injection device becomes high, the force with which the foreign matter in the fuel collides with the seat portion of the first valve body is also strong, which may cause the seat portion to be corroded Be done. When the seat portion is corroded, the fuel flows out from the control chamber to the discharge chamber even if the on-off valve is closed, and the pressure increase speed in the control chamber is reduced. Then, as the pressure increase speed in the control chamber decreases, the time for the nozzle needle to close the fuel injection hole also becomes late, and more fuel than the planned amount will be injected into the combustion chamber of the engine. . For this reason, it is important to take measures to suppress the erosion of the seat portion in preparation for further increasing the pressure of the fuel supplied to the fuel injection device.

  The present invention has been made to solve the above-mentioned problems, and it is possible to suppress the erosion of the seat portion more than before even when the fuel supplied to the fuel injection device becomes high pressure. The aim is to get

  The fuel injection device according to the present invention comprises: a main body portion formed at one end with a fuel injection hole for injecting fuel; and a nozzle needle which is reciprocally provided inside the main body portion to open and close the fuel injection hole. It is formed inside the main body so as to face the first end, which is the end opposite to the fuel injection hole side of the nozzle needle, through the control chamber into which the fuel flows, and the communication passage. The fuel cell system further includes: a discharge chamber in communication with the control chamber, the fuel flowing into the control chamber flowing through the communication passage, and an on-off valve for opening and closing the communication passage; A fuel injection device that acts on the first end of the nozzle needle and utilizes the pressure for driving the nozzle needle, wherein the on-off valve has a first valve body having a flat sheet portion, and Protruding at the position facing the seat A second valve body having a second valve body, the flow path between the first valve body and the second valve body being closed by the protrusion coming into contact with the seat portion to be in a closed state And the first valve body is positioned on the upstream side of the seat portion in the flow direction of the fuel flowing in the flow path between the first valve body and the second valve body from the seat portion Also, a stepped portion protruding toward the second valve body is formed.

  In the second valve body, a relief portion recessed on the opposite side to the first valve body may be formed in a range facing the step portion of the first valve body.

  In the fuel injection device according to the present invention, the first valve body in which the seat portion is formed is located upstream of the seat portion in the flow direction of the fuel flowing between the first valve body and the second valve body. The step part which protrudes in the 2nd valve body side rather than a sheet | seat part is formed in this position. That is, when observing the surface of the first valve body on the side facing the second valve body, at a position behind the step in the flow direction of the fuel flowing between the first valve body and the second valve body, A recess that is recessed on the opposite side to the second valve body is formed. For this reason, when fuel flows through the flow path between the first valve body and the second valve body, stagnation of the fuel is generated at the recessed portion. Then, in the fuel injection device according to the present invention, the seat portion can be disposed in the range where the stagnation occurs. In the range where the stagnation occurs, the fuel does not flow much compared to the other range of the flow path between the first valve body and the second valve body. Therefore, the amount of foreign matter colliding with the sheet portion can be reduced. In addition, the flow rate of the fuel is small in the range where the stagnation occurs. For this reason, even when foreign matter collides with the sheet portion, the force at the time when the foreign matter collides with the sheet portion can be reduced. Therefore, the fuel injection device according to the present invention can suppress the erosion of the seat portion more than before even when the fuel supplied to the fuel injection device becomes high pressure.

  Further, in the fuel injection device according to the present invention, the relief portion is formed by forming a relief portion recessed on the opposite side to the first valve body in a range facing the step portion of the first valve body in the second valve body. Even if the distance between the step portion and the seat portion is reduced as compared with the case where it is not formed, the contact between the step portion and the second valve body can be prevented, and the on-off valve can be prevented from closing. it can. The above-mentioned stagnation becomes larger when it is closer to the step. That is, in the range in which stagnation is generated, the fuel is less likely to flow and the flow rate of the fuel is reduced in the direction closer to the step. Therefore, by forming the relief portion in the second valve body, the distance between the step portion and the seat portion can be reduced, and therefore, erosion of the seat portion can be further suppressed.

It is a sectional view showing a fuel injection device concerning an embodiment of the invention. It is the Q section enlarged view of FIG. Principal part enlarged view (cross-sectional view) showing the configuration in the vicinity of the contact portion between the valve plate and the valve needle of the on-off valve used to open and close the communication passage between the control chamber and the discharge chamber in the conventional fuel injection device It is.

Embodiment.
Hereinafter, an embodiment relating to the fuel injection device of the present invention will be specifically described. However, the present embodiment shows one aspect of the present invention, does not limit the present invention, and can be arbitrarily changed within the scope of the present invention.
In the present embodiment, the end on the side where the fuel injection hole is formed is the lower end of the fuel injection device, and the end on the side opposite to the end on the fuel injection hole side is the upper end of the fuel injection device. The fuel injection device will be described.

[overall structure]
FIG. 1 is a cross-sectional view showing a fuel injection device according to an embodiment of the present invention.
The fuel injection device 100 includes a main body 1 in which a fuel injection hole 3 for injecting fuel is formed at the lower end. In the present embodiment, the main body 1 is configured by the nozzle main body 2, the union nut 4 and the closing plate 5. In addition, these components which comprise the main-body part 1 are an example to the last. Depending on the design of the fuel injection device 100, the number of divisions of the main body 1, in other words, the number of parts constituting the main body 1, can be arbitrarily changed.

  The nozzle main body 2 constitutes a lower portion of the main body 1. The union nut 4 constitutes an upper portion of the main body 1 and is formed in a tubular shape. The nozzle body 2 is airtightly fixed to the lower end portion of the union nut 4 by, for example, press fitting. Further, the upper end portion of the union nut 4 is airtightly closed by the closing plate 5.

  A high pressure chamber 52 is formed inside the nozzle body 2. The high-pressure chamber 52 is supplied with high-pressure fuel from the outside (for example, a common rail, a fuel pump, etc.) via a fuel inlet 51 formed in the nozzle body 2 and the union nut 4. A fuel injection hole 3 is formed at the lower end of the nozzle body 2. The high pressure fuel in the high pressure chamber 52 is injected to the combustion chamber (not shown) through the fuel injection holes 3.

  The upper end (that is, the end opposite to the fuel injection hole 3 side) of the high pressure chamber 52 is defined by the valve plate 21. The valve plate 21 is sandwiched between the fixing ring 4 a attached to the inner peripheral surface of the union nut 4 and the nozzle body 2, and airtightly closes the high pressure chamber 52. On the surface of the valve plate 21 on the high pressure chamber 52 side, a cylindrical projection surrounding the control chamber 10 is formed. The end of the cylindrical projection opposite to the valve plate 21 is closed by the wall 11. Moreover, the nozzle needle opening part in which the below-mentioned nozzle needle 6 is inserted is formed in the said wall 11. As shown in FIG. Further, in the cylindrical projection surrounding the control chamber 10, a communication passage 12 for communicating the control chamber 10 with the high pressure chamber 52 is formed. That is, the high pressure fuel in the high pressure chamber 52 flows into the control chamber 10 through the communication passage 12.

  A nozzle needle 6 is provided inside the nozzle body 2 so as to be reciprocable along the axis of the high pressure chamber 52 (vertically movable in FIG. 1). The nozzle needle 6 opens and closes the fuel injection hole 3. The nozzle needle 6 has an upper end 6 a on the control chamber 10 side and a lower end 6 b on the fuel injection hole 3 side. The nozzle needle 6 can be configured integrally or can be configured from a plurality of components that are operatively connected to each other. Here, the upper end 6a corresponds to the first end of the present invention.

  The upper end 6 a of the nozzle needle 6 is inserted into a nozzle needle opening formed in the wall 11 and protrudes into the control chamber 10. In other words, it can be said that the control chamber 10 is formed in the main body 1 so as to face the upper end 6 a of the nozzle needle 6. As the nozzle needle 6 reciprocates, the volume of the control chamber 10 is changed. Further, on the outer peripheral surface of the nozzle needle 6, a hook-like protrusion 8 is formed at a position below the wall 11.

  Further, a spring 9 for urging the nozzle needle 6 to the fuel injection hole 3 side is provided between the projection 8 and the wall 11, and the nozzle needle 6 faces downward (that is, approaches the fuel injection hole 3). Direction) will be applied. Further, a step 7 is formed above the lower end 6 b of the nozzle needle 6. The pressure of the high-pressure fuel in the high-pressure chamber 52 acts on the step 7 to apply an upward force (that is, a direction away from the fuel injection holes 3) to the nozzle needle 6. A seat portion is formed in a portion of the nozzle body 2 connected to the fuel injection hole 3, and the fuel injection hole 3 is closed by the nozzle needle 6 being seated (seated) on the seat portion. The high pressure fuel is not injected from the fuel injection holes 3. On the other hand, when the nozzle needle 6 is separated (lifted) from the seat portion, the fuel injection hole 3 is opened, and the high pressure fuel in the high pressure chamber 52 is injected from the fuel injection hole 3.

  A discharge chamber 30 is formed on the side opposite to the control chamber 10 in the valve plate 21 by being surrounded by a cylindrical wall 31 and a wall 33 closing the upper end of the wall 31. Further, the valve plate 21 is formed with a through hole 13 a which is a part of the structure of the communication passage 13 which causes the control chamber 10 and the discharge chamber 30 to communicate with each other. A valve needle 25 is disposed on the discharge chamber 30 side of the valve plate 21. The valve needle 25 constitutes the on-off valve 20 together with the valve plate 21.

The valve needle 25 is reciprocable (up and down movable in FIG. 1) in the direction toward the valve plate 21 and in the direction away from the valve plate 21 as described later. Then, the tip end of the valve needle 25 on the valve plate 21 side (protruding portion 27 in FIG. 2 described later) contacts the outer peripheral side (the sheet portion 22 in FIG. 2 described later) of the opening of the through hole 13a in the valve plate 21 In the state, that is, in the state where the on-off valve 20 is closed, the flow path between the valve plate 21 and the valve needle 25 (flow path 13 b in FIG. 2 described later) is closed. In the state where the tip of the valve needle 25 on the valve plate 21 side is away from the outer peripheral side of the opening of the through hole 13 a in the valve plate 21, that is, in the state where the on-off valve 20 is opened. And the flow path between them (the flow path 13 b in FIG. 2 described later) is opened. That is, the communication passage 13 communicating the control chamber 10 with the discharge chamber 30 is constituted by the through hole 13 a formed in the valve plate 21 and the flow passage 13 b between the valve plate 21 and the valve needle 25. . The on-off valve 20 opens and closes the communication passage 13.
The detailed configuration of the vicinity of the contact portion between the valve plate 21 and the valve needle 25 in the on-off valve 20 (the Q portion enclosed by a two-dot chain line in FIG. 1) will be described later with reference to FIG.

  As described above, when the on-off valve 20 is opened, the control chamber 10 and the discharge chamber 30 communicate with each other through the communication passage 13 (through hole 13a, flow passage 13b). For this reason, the fuel in the control chamber 10 flows into the discharge chamber 30 through the communication passage 13. Here, the flow passage cross-sectional area of the through hole 13 a and the flow passage 13 b constituting the communication passage 13 is larger than the flow passage cross-sectional area of the communication passage 12 communicating the high pressure chamber 52 with the control chamber 10. Therefore, when the on-off valve 20 is opened, the amount of fuel flowing out from the control chamber 10 to the discharge chamber 30 becomes larger than the amount of fuel flowing from the high pressure chamber 52 into the control chamber 10. Therefore, when the on-off valve 20 is opened, the pressure of the fuel in the control chamber 10 is lower than the pressure of the fuel in the high pressure chamber 52.

  For example, two outlet holes 32 are formed in the wall 31 surrounding the discharge chamber 30. The outlet hole 32 is a through hole communicating the discharge chamber 30 with the low pressure chamber 53 formed above the valve plate 21 in the union nut 4. The low pressure chamber 53 communicates with a fuel outlet 54 that discharges the fuel supplied into the fuel injection device 100 to the outside. Therefore, high fuel pressure is not formed in the low pressure chamber 53.

  The valve needle 25 extends into the low pressure chamber 53 through an opening formed in the wall 33 surrounding the top of the discharge chamber 30. That is, the upper end (the end opposite to the valve plate 21) of the valve needle 25 protrudes upward beyond the wall 33. An armature plate 41 is provided at the upper end of the valve needle 25. The armature plate 41 extends in the low pressure chamber 53 at a right angle to the longitudinal direction of the fuel injection device 100. The armature plate 41 may be formed integrally with the valve needle 25.

  A spring 42 is disposed between the armature plate 41 and the closing plate 5. The spring 42 biases the armature plate 41 toward the valve plate 21 so that the valve needle 25 is pressed onto the valve plate 21 and the space between them is closed.

  An electromagnet 43 is also provided between the armature plate 41 and the closing plate 5. The armature plate 41 moves upward against the force of the spring 42 by the operation of the electromagnet 43 (by supplying power to the electromagnet 43). That is, the valve needle 25 attached to the armature plate 41 moves in the direction in which the on-off valve 20 opens. That is, the on-off valve 20 is opened by the operation 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 further flows into the low pressure chamber 53 and the fuel outlet 54 through the outlet hole 32. Do.

When the pressure of the fuel in the control chamber 10 is reduced due to the outflow of the fuel from the control chamber 10, the pressure of the fuel in the control chamber 10 is equal to the pressure of the fuel in the high pressure chamber 52 acting on the step 7 of the nozzle needle 6. By contrast, it is no longer sufficient to hold the nozzle needle 6 in the lower closed position. For this reason, when the pressure of the fuel in the control chamber 10 decreases due to the outflow of the fuel from the control chamber 10, the nozzle needle 6 moves upward and opens the fuel injection hole 3. Thus, the fuel in the high pressure chamber 52 is injected through the fuel injection holes 3 into a combustion chamber (not shown).
That is, the fuel injection device 100 according to the present embodiment is a fuel injection device that causes the pressure of the fuel in the control chamber 10 to act on the upper end 6 a of the nozzle needle 6 and uses the pressure to drive the nozzle needle 6. .

  In order to end the injection of fuel from the fuel injection holes 3, the supply of power to the electromagnet 43 is stopped. Thereby, the armature plate 41 is pressed by the spring 42 to the lower closed position. Then, together with the armature plate 41, the valve needle 25 also moves downward and contacts the valve plate 21. That is, the on-off valve 20 is closed. When the on-off valve 20 is closed, the fuel flowing from the high pressure chamber 52 into the control chamber 10 through the communication passage 12 can not flow out from the control chamber 10 into the discharge chamber 30. For this reason, the pressure of the fuel in the control chamber 10 is increased. The increased pressure in the control chamber 10 exerts on the nozzle needle 6 a downward force which, together with the force of the spring 9, presses the nozzle needle 6 down to the closed position. As a result, the nozzle needle 6 descends, and the lower end portion 6 b of the nozzle needle 6 closes the fuel injection hole 3. As a result, no further fuel is injected from the high pressure chamber through the fuel injection holes 3 into the combustion chamber.

  A valve needle hole 26 is formed in the valve needle 25 along the longitudinal axis of the fuel injection device 100. A pressure pin 61 is inserted in the valve needle hole 26 in an airtight manner against high pressure. Further, the pressure pin 61 can move in the valve needle hole 26 in parallel with the moving direction of the nozzle needle 6 and the valve needle 25 along the longitudinal axis of the fuel injection device 100. The pressure pin 61 extends through the center of the hole formed in the armature plate 41, the spring 42 and the electromagnet 43. The pressure pin 61 is disposed such that a force acting on the lower end surface is transmitted to the sensor 63 which is, for example, a pressure sensor via the upper end surface.

  In the present embodiment, the correction element 62 is provided between the upper end surface of the pressure pin 61 and the sensor 63. This correction element 62 makes it possible to correct the angular tolerance between the sensor 63 and the pressure pin 61 and to increase the accuracy of the measurement performed by the sensor 63.

  When the valve needle 25 is moving downward, that is, when the on-off valve 20 is closed and the control chamber 10 and the discharge chamber 30 are not in communication, the high fuel existing in the control chamber 10 The pressure acts on the lower end surface of the pressure pin 61 through the through hole 13a. The pressure pin 61 transmits a force proportional to the fuel pressure in the control chamber 10 to the sensor 63. At this time, since the control chamber 10 communicates with the high pressure chamber 52 through the communication passage 12, the fuel pressure in the control chamber 10 is kept the same as the fuel pressure in the high pressure chamber 52 while the balance of the hydraulic pressure is maintained. It is. Thus, the force exerted by the pressure pin 61 on the sensor 63 is proportional to the fuel pressure in the high pressure chamber 52. The fuel pressure in the high pressure chamber 52 can be easily determined from the value measured by the sensor 63.

[Details of the on-off valve 20]
Subsequently, the detailed configuration in the vicinity of the contact portion between the valve plate 21 and the valve needle 25 in the on-off valve 20 will be described.

  FIG. 2 is an enlarged view of a portion Q in FIG. FIG. 2 shows the valve plate 21 and the valve needle 25 in a state where the on-off valve 20 is open. The black arrow at the end shown in FIG. 2 indicates the flow direction of the fuel in the flow passage 13 b when the on-off valve 20 is open.

The valve plate 21 has a flat sheet portion 22 on the surface of the area facing the valve needle 25. The seat portion 22 is formed in an annular shape so as to surround the outer peripheral side of the opening on the valve needle 25 side of the through hole 13a. In FIG. 2, the range of the sheet portion 22 is also indicated by a thick two-dot chain line. Further, the valve needle 25 has an annular projecting portion 27 at a position facing the seat portion 22 of the valve plate 21 at the tip end portion. When the valve needle 25 descends and contacts the valve plate 21 as described above, that is, when the on-off valve 20 is closed, the projection 27 of the valve needle 25 contacts the seat of the valve plate 21.
That is, the valve plate 21 corresponds to a first valve body of the present invention, and the valve needle 25 corresponds to a second valve body of the present invention.

  As shown in FIG. 2, when the on-off valve 20 is in the open state, the outer peripheral side of the through hole 13 a which is a part of the communication passage 13 is surrounded between the valve plate 21 and the valve needle 25. An annular flow passage 13 b is formed as another portion of the communication passage 13. Then, the fuel flowing from the control chamber 10 into the flow passage 13 b through the through hole 13 a flows out to the discharge chamber 30 through the flow passage 13 b. When the on-off valve 20 is closed, the projecting portion 27 of the valve needle 25 contacts the seat portion 22 of the valve plate 21 to close the flow passage 13b, whereby the communication passage 13 is closed.

  Furthermore, in the valve plate 21 of the on-off valve 20 according to the present embodiment, on the valve needle 25 side of the seat portion 22 at a position upstream of the seat portion 22 in the flow direction of the fuel flowing through the flow path 13b. A protruding step 23 is formed. The stepped portion 23 is formed between the opening of the through hole 13 a and the seat portion 22 on the surface of the valve plate 21 facing the valve needle 25. Furthermore, in the valve needle 25 of the on-off valve 20 according to the present embodiment, a relief 28 that is recessed on the opposite side to the valve plate 21 is formed in a range facing the step 23 of the valve plate 21.

  By forming the stepped portion 23 in the valve plate 21, even when the fuel supplied to the fuel injection device 100 is at a high pressure, the effect of suppressing the erosion of the seat portion 22 can be obtained more than in the past. Hereinafter, in order to facilitate understanding of the effects, the configuration of the on-off valve 120 used to open and close the communication passage between the control chamber and the discharge chamber in the conventional fuel injection device will be described. After that, the reason why the fuel injection device 100 according to the present embodiment can obtain the above-described effect will be described.

  FIG. 3 is a main part enlarged view showing the configuration in the vicinity of the contact portion between the valve plate and the valve needle of the on-off valve used for opening and closing the communication passage between the control chamber and the discharge chamber in the conventional fuel injection device. FIG. This FIG. 3 shows the same range as the above-mentioned FIG. FIG. 3 shows the valve plate 121 and the valve needle 125 in a state where the on-off valve 120 is open. Further, in FIG. 3, among the configurations of the conventional fuel injection device, the same configurations as fuel injection device 100 according to the present embodiment are given the same reference numerals as fuel injection device 100 according to the present embodiment. . Further, the black arrow at the end shown in FIG. 3 indicates the flow direction of the fuel in the flow path 13b when the on-off valve 120 is open.

  The conventional fuel injection device is provided with the on-off valve 120 shown in FIG. 3 as an opening / closing device for opening / closing the communication path between the control chamber and the discharge chamber. The on-off valve 120 includes a valve plate 121 and a valve needle 125. The difference between the valve plate 121 of the conventional on-off valve 120 and the valve plate 21 according to the present embodiment is that the stepped portion 23 is not formed on the valve plate 121. The other configuration of the valve plate 121 is the same as the configuration of the valve plate 21 according to the present embodiment.

  The difference between the valve needle 125 of the conventional on-off valve 120 and the valve needle 25 according to the present embodiment is that the relief portion 28 is not formed in the valve needle 125. The other configuration of the valve needle 125 is the same as that of the valve needle 25 according to the present embodiment.

  The opening / closing operation of the conventional on-off valve 120 is the same as that of the on-off valve 20 according to the present embodiment. That is, the valve needle 125 is freely reciprocable (up and down movable in FIG. 3) in the direction toward the valve plate 121 and in the direction away from the valve plate 121. Then, in a state in which the projecting portion 27 of the valve needle 125 contacts the seat portion 22 of the valve plate 121, that is, in a state where the on-off valve 120 is closed, the flow path 13b between the valve plate 121 and the valve needle 125 is closed. . Further, when the projection 27 of the valve needle 125 is separated from the seat portion 22 of the valve plate 121, that is, when the on-off valve 120 is open, the flow path 13b between the valve plate 121 and the valve needle 125 opens. As a result, the fuel flowing from the control chamber into the flow passage 13b through the through hole 13a flows out to the discharge chamber through the flow passage 13b.

  The flow path 13b formed between the valve plate 121 and the valve needle 125 when the on-off valve 120 is opened is the tip position of the protrusion 27 of the valve needle 125 when observed along the fuel flow direction. The channel cross-sectional area will be reduced to the end. For this reason, the fuel flowing through the flow path 13 b flows so as to collide with the seat portion 22 of the valve plate 121 disposed at a position facing the projection 27 of the valve needle 125. Therefore, when the foreign matter 200 is mixed in the fuel, the foreign matter 200 mixed in the fuel also collides with the seat portion 22 of the valve plate 121 when the fuel flows through the flow path 13 b. The amount of foreign matter 200 in the fuel varies depending on the degree of fuel cleanliness and the environment in which the fuel injection device (in other words, the engine equipped with the fuel injection device) is used.

  Here, in recent years, the pressure of the fuel supplied to the fuel injection device has become high. Then, further increase in the pressure of fuel supplied to the fuel injection device is expected in the future. As described above, when the pressure of the fuel supplied to the fuel injection device becomes high, the force with which the foreign matter 200 in the fuel collides with the seat portion 22 of the valve plate 121 also increases, and the seat portion 22 is corroded. Are concerned. When the seat portion 22 is corroded, even if the on-off valve 120 is closed, the fuel flows out from the control chamber to the discharge chamber, and the pressure increase speed in the control chamber is reduced. Then, as the pressure increase speed in the control chamber decreases, the time for the nozzle needle to close the fuel injection hole also becomes late, and more fuel than the planned amount will be injected into the combustion chamber of the engine. . For this reason, it is important to take measures to suppress the erosion of the seat portion 22 in preparation for further increasing the pressure of the fuel supplied to the fuel injection device.

  For example, it is conceivable to apply a coating to the surface of the sheet portion 22 as one of the configurations for suppressing the erosion of the sheet portion 22. However, when it is intended to suppress the erosion of the sheet portion 22 by the coating, a coating cost, a management cost for maintaining the coating quality, and the like occur. For these reasons, the cost of the fuel injection device also increases with these costs. Therefore, the inventor has diligently studied a configuration that can suppress the erosion of the seat portion 22 while suppressing the increase in the price of the fuel injection device. And an inventor came to the structure of the on-off valve 20 shown in FIG. 2 as a result of earnest examination.

  As shown in FIG. 2, the valve plate 21 of the on-off valve 20 of the fuel injection device 100 according to the present embodiment is a seat at a position upstream of the seat portion 22 in the flow direction of fuel flowing through the flow passage 13 b. A stepped portion 23 is formed which protrudes further toward the valve needle 25 than the portion 22. That is, when the surface of the valve plate 21 on the side facing the valve needle 25 is observed, a recess that is recessed to the opposite side of the valve needle 25 to a position behind the step 23 in the flow direction of fuel flowing through the flow path 13b. Will be formed. For this reason, when fuel flows through the flow path 13b, stagnation of the fuel is generated at the recessed portion. Then, in the fuel injection device 100 according to the present embodiment, the seat portion 22 can be disposed in the range where the stagnation occurs.

  In the range where the stagnation occurs, the fuel does not flow much compared to the other range of the flow path 13b. For this reason, the amount of the foreign material 200 colliding with the sheet portion 22 can be reduced. In addition, the flow rate of the fuel is small in the range where the stagnation occurs. Therefore, even when the foreign matter 200 collides with the sheet portion 22, the force at the time when the foreign matter 200 collides with the sheet portion 22 can be reduced. Therefore, even when the fuel supplied to the fuel injection device 100 becomes high pressure, the fuel injection device 100 according to the present embodiment can suppress the erosion of the seat portion 22 more than in the past.

  Furthermore, in the fuel injection device 100 according to the present embodiment, the valve needle 25 of the on-off valve 20 is a relief 28 that is recessed to the opposite side to the valve plate 21 in a range facing the step 23 of the valve plate 21. Is formed. The above-mentioned stagnation becomes larger when it is closer to the step portion 23. That is, in the range in which stagnation occurs, the one nearer to the step portion 23 makes it difficult for the fuel to flow, and the speed at which the fuel flows is also reduced. Here, by forming the relief portion 28 in the valve needle 25 of the on-off valve 20, the distance between the step portion 23 and the seat portion 22 is reduced as compared with the case where the relief portion 28 is not formed. Also, the contact between the step portion 23 and the valve needle 25 can be prevented, and the closing of the on-off valve 20 can be prevented. Therefore, by forming the relief portion 28 in the valve needle 25, the distance between the step portion 23 and the seat portion 22 can be reduced, and therefore erosion of the seat portion 22 can be further suppressed. .

  In the present embodiment, the seat portion 22 is formed on the valve plate 21 and the projecting portion 27 is formed on the valve needle 25. Not limited to this, the projecting portion 27 may be formed on the valve plate 21, and the seat portion 22 may be formed on the valve needle 25. When the seat portion 22 is formed on the valve needle 25, the valve needle 25 has a valve plate at a position on the upstream side of the seat portion 22 in the flow direction of the fuel flowing through the flow passage 13 b. A step 23 projecting to the side 21 is formed. Even if the stepped portion 23 is formed in this manner, erosion of the sheet portion 22 can be suppressed more than in the past. That is, in the case where the seat portion 22 is formed on the valve needle 25, the valve needle 25 corresponds to the first valve body of the present invention, and the valve plate 21 corresponds to the second valve body of the present invention.

  Further, in the configuration in which the seat portion 22 is formed on the valve needle 25, the relief portion 28 may be formed on the valve plate 21 when the relief portion 28 is provided. Since the distance between the step portion 23 and the sheet portion 22 can be reduced, erosion of the sheet portion 22 can be further suppressed.

  As described above, in the fuel injection device 100 according to the present embodiment, the fuel injection hole 3 for injecting the fuel is provided in the main body 1 having the lower end (one end) formed in the lower end (one end). It is formed inside the main body 1 so as to face the nozzle needle 6 for opening and closing the injection hole 3 and the upper end 6a of the nozzle needle 6 (the end opposite to the fuel injection hole 3 side), and fuel flows in A control chamber 10, a discharge chamber 30 in communication with the control chamber 10 via the communication passage 13, and a fuel flowing into the control chamber 10 flowing in via the communication passage 13, an opening / closing valve 20 for opening and closing the communication passage 13; The pressure of fuel in the control chamber 10 is applied to the upper end 6 a of the nozzle needle 6, and the pressure is used to drive the nozzle needle 6. Further, the on-off valve 20 of the fuel injection device 100 according to the present embodiment faces the first valve body (one of the valve plate 21 and the valve needle 25) having the flat surface sheet portion 22 and the seat portion 22. And the second valve body (the other of the valve plate 21 and the valve needle 25) having the projecting portion 27 at the position where the first valve body and the second valve body It is a structure which closes the flow path between valve bodies, and will be in a closed state. In the fuel injection device 100 according to the present embodiment, the first valve body is closer to the fuel flow in the flow path 13b between the first valve body and the second valve body than the seat portion 22. At a position on the upstream side, a stepped portion 23 that protrudes toward the second valve body side relative to the seat portion 22 is formed.

  The fuel injection device 100 according to the present embodiment can generate stagnation in the fuel flowing through the flow passage 13 b by the step portion 23. Then, in the fuel injection device 100 according to the present embodiment, the seat portion 22 can be disposed in the range where the stagnation occurs. Therefore, the fuel injection device 100 according to the present embodiment can reduce the amount of the foreign matter 200 colliding with the seat portion 22, and can also reduce the force when the foreign matter 200 collides with the seat portion 22. . Therefore, even when the fuel supplied to the fuel injection device 100 becomes high pressure, the fuel injection device 100 according to the present embodiment can suppress the erosion of the seat portion 22 more than in the past.

  In addition, you may form the relief part 28 dented on the opposite side to a 1st valve body in the range facing the step part 23 of the 1st valve body in a 2nd valve body. By forming the relief portion 28 in the valve needle 25, the distance between the step portion 23 and the seat portion 22 can be reduced, so that the erosion of the seat portion 22 can be further suppressed.

Reference Signs List 1 main body, 2 nozzles main body, 3 fuel injection holes, 4 union nut, 4a fixing ring, 5 closing plate, 6 nozzle needle, 6a upper end, 6b lower end, 7 step, 8 projection, 9 spring, 10 control 11 walls, 12 communication passages, 13 communication passages, 13a through holes, 13b passages, 20 on-off valves, 21 valve plates, 22 seat portions, 23 steps, 25 valve needles, 26 valve needle holes, 27 protrusions, 28 relief part, 30 discharge chamber, 31 wall, 32 outlet hole, 33 wall, 41 armature plate, 42 spring, 43 electromagnet, 51 fuel inlet, 52 high pressure chamber, 53 low pressure chamber, 54 fuel outlet, 61 pressure pin, 62 correction Element, 63 sensor, 100 fuel injection device, 120 on-off valve (conventional), 121 valve plate (conventional), 125 valve needle (conventional), 200 foreign matter.

Claims (2)

A main body portion formed at one end with a fuel injection hole for injecting fuel;
A nozzle needle which is provided in the main body so as to reciprocate, and which opens and closes the fuel injection hole;
A control chamber formed inside the main body to face a first end which is an end opposite to the fuel injection hole side of the nozzle needle, and into which the fuel flows;
A discharge chamber in communication with the control chamber via a communication passage, the fuel flowing into the control chamber flowing in via the communication passage;
An on-off valve for opening and closing the communication passage;
Equipped with
A fuel injection system, wherein the pressure of the fuel in the control chamber is applied to the first end of the nozzle needle, and the pressure is used to drive the nozzle needle.
The on-off valve is
A first valve body having a flat sheet portion;
A second valve body having a projection at a position facing the seat;
Equipped with
By contacting the projection with the seat portion, the flow path between the first valve body and the second valve body is closed to be in a closed state.
The first valve body is
It protrudes on the second valve body side more than the seat portion at a position on the upstream side of the seat portion in the flow direction of the fuel flowing in the flow path between the first valve body and the second valve body A fuel injection device in which a step is formed. 2. The fuel injection device according to claim 1, wherein the second valve body is formed with a relief portion which is recessed on the opposite side to the first valve body in a range facing the step portion of the first valve body.

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