JP2009156059A - Fuel injection valve and fuel injection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a fuel injection characteristic of a fuel injection device by suppressing an influence of the fluctuation of fuel pressure caused by a pressure source. <P>SOLUTION: The fuel injection device 1 is equipped with a fuel injection valve 2 and a switching valve 3. The fuel injection valve 2 is equipped with a nozzle body 5 with an injection hole 4 formed at its tip, a piston 7 stored in the nozzle body 5 for forming a back pressure chamber 8 on a base end side in the nozzle body 5 and also forming a metering chamber 9 at a tip side, a first fuel passage 10 and a second fuel passage 11 for making the back pressure chamber 8 communicate with the metering chamber 9, and a valve body 14 opening accompanied by the movement of the piston 7 caused by fuel introduction from a common rail to the back pressure chamber 8. The switching valve 3 switches a state of introducing the fuel from the common rail to the back pressure chamber 8, a state of connecting the back pressure chamber 8 and the metering chamber 9, and a state of blocking the communication between the back pressure chamber 8 and the metering chamber 9 and blocking communication between the back pressure chamber 8 and the common rail. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel injection valve and a fuel injection device for an internal combustion engine.

  2. Description of the Related Art Conventionally, a fluid supply device that supplies fluid into a cylinder formed in an engine is known. One of such fluid supply devices includes a pressure source unit that supplies a fluid for injection, and an injection valve that injects fluid supplied from the pressure source unit into the cylinder, and the pressure source unit and the injection valve In some cases, there is provided a metering mechanism for controlling the amount of fluid supplied into the cylinder.

  An improved version of such a fluid supply apparatus is disclosed in Patent Document 1. In the fluid supply device disclosed in Patent Document 1, a measuring cylinder is disposed between a pressure source unit and an injection valve. A piston is disposed inside the measuring cylinder, and the measuring cylinder is partitioned into a measuring chamber and a pressure chamber by the piston. The measuring chamber is connected to the pressure source unit via an electromagnetic valve, and fluid is supplied to the measuring chamber by opening the electromagnetic valve. Moreover, such a fluid supply apparatus includes a detector that detects the piston position. In the fluid supply device, the control device accumulates the fluid in the measurement chamber based on the piston position detection result obtained from the detector and the fluid supply amount target value.

JP 2007-85214 A

  By the way, such a fluid supply apparatus can be applied to an engine fuel injection apparatus. Such a fuel injection device suppresses variations in the amount of fuel supplied to the fuel injection valve caused by the influence of pressure fluctuations in the common rail. However, when such a fluid supply device is applied to a fuel injection device, the fuel injection device leaves room for improving the fuel injection characteristics.

  Accordingly, an object of the present invention is to suppress the influence of fuel pressure fluctuations caused by a pressure source and improve fuel injection characteristics in a fuel injection device.

  A fuel injection valve according to the present invention that solves such a problem includes a nozzle body having a nozzle hole formed at a tip thereof, and is accommodated in the nozzle body, and a back pressure chamber is formed on a proximal end side in the nozzle body. In addition, a piston that forms a metering chamber on the tip side, a fuel passage that allows or blocks communication between the back pressure chamber and the metering chamber, and a piston that is introduced into the back pressure chamber by introducing fuel from outside. And a valve body that opens with movement (claim 1). With this configuration, fuel injection and metering can be performed separately at different timings, so that metered fuel can be injected with high accuracy.

  Some fuel injection valves using a common rail perform injection and metering simultaneously when the valve element is opened. On the other hand, in the fuel injection valve of the present invention, the fuel injection process and the fuel metering process are separate. Explaining these steps with the movement of the piston, in the fuel injection valve of the present invention, the piston moves to the base end side, so that the fuel in the back pressure chamber stored in advance is filled into the metering chamber. . On the other hand, the fuel in the metering chamber is injected by moving the piston toward the tip side. As described above, the fuel injection process and the fuel metering process are separated from each other, so that there is no influence of the pressure pulsation of the common rail during metering. For this reason, stable metering accuracy is obtained, and the injection characteristics such as the injection amount accuracy and the injection rate can be improved. Further, since the fuel supplied to the back pressure chamber is then sent to the metering chamber and injected, most of the pressurized fuel is injected. For this reason, useless pressurization of fuel can be suppressed. Furthermore, since the back pressure chamber and the metering chamber are formed in the same cylinder, fuel leakage can be suppressed.

  In such a fuel injection valve, a storage chamber that is formed on the distal end side of the metering chamber in the nozzle body, stores the valve body, and a communication path that connects the storage chamber and the metering chamber; An elastic body that urges the valve body toward the communication path to close the communication path (Claim 2).

  In such a fuel injection valve, the piston is formed in a cylindrical shape, and the valve body is a needle valve that is slidably housed inside the piston and closes the injection hole. It can be set as the structure formed in the said valve body (Claim 3). By setting it as such a structure, the leakage of the fuel from a nozzle hole at the time of an injection stop can be suppressed. Thereby, the engine equipped with the fuel injection valve of the present invention can suppress the generation of HC.

  In the fuel injection valve of the present invention, the pressure receiving area on the back pressure chamber side of the piston may be wider than the pressure receiving area on the metering chamber side. By adopting such a configuration, the fuel in the metering chamber can be made higher than the fuel in the back pressure chamber, so that the fuel can be injected at a high pressure.

  Such a fuel injection valve can be configured to include a check valve in the fuel passage (claim 5). By setting it as such a structure, the back flow of the fuel with which the metering chamber was filled is suppressed. Thereby, high-pressure fuel can be injected.

  Such a fuel injection valve may be configured to include a return passage connected to the fuel passage and a relief valve disposed in the return passage (claim 6). By setting it as such a structure, it can suppress that the pressure in a metering chamber rises. Thereby, the pressure rise in the metering chamber other than at the time of injection is suppressed, and fuel injection is suppressed.

  Further, such a fuel injection valve can be configured to include a measuring means for measuring the amount of fuel in the metering chamber (claim 7). By adopting such a configuration, the fuel metering accuracy can be further improved. Such a measuring means can measure the fuel filling amount in the metering chamber from the lift amount of the piston. In this way, fuel metering can be performed while measuring the fuel filling amount. Thereby, metering accuracy can be improved.

  The fuel injection device of the present invention that solves the above problems comprises any one of the fuel injection valves of the present invention, a state in which fuel is introduced from the outside into the back pressure chamber, the back pressure chamber, and the metering chamber. Switching means for switching between a connected state and a state in which communication between both the back pressure chamber and the metering chamber and the outside is cut off is provided (Claim 8). By setting it as such a structure, the connection state in a back pressure chamber and a metering chamber can be switched, and fuel injection and fuel metering can be implement | achieved.

  The fuel injection valve of the present invention can improve injection characteristics by separately performing fuel injection and fuel metering. Moreover, unnecessary fuel pressurization can be suppressed, and fuel leakage can be suppressed.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

  Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory view showing a fuel injection device 1 of the present invention. The fuel injection device 1 includes a fuel injection valve 2 and a switching valve 3 corresponding to the switching means of the present invention.

  First, the configuration of the fuel injection valve 2 will be described. The fuel injection valve 2 includes a nozzle body 5 having a nozzle hole 4 formed at the tip. A cylinder 6 is formed inside the nozzle body 5. The cylinder 6 has a convex portion 6a. Further, the fuel injection valve 2 is provided with a piston 7 that slides in the cylinder 6. The piston 7 includes a piston part 7a, a neck part 7b, and a base end part 7c. The piston portion 7a is slidably disposed on the cylinder 6 on the tip side of the convex portion 6a. Accordingly, the piston 7 forms a back pressure chamber 8 on the proximal end side inside the cylinder 6 and forms a metering chamber 9 on the distal end side inside the cylinder 6. A first fuel passage 10 extends from the back pressure chamber 8. A second fuel passage 11 extends from the metering chamber 9. The first fuel passage 10 and the second fuel passage 11 can be connected within the switching valve 3. The first fuel passage 10 and the second fuel passage 11 communicate with each other through the switching valve 3 to constitute the fuel passage of the present invention. Further, the first spring 12 is held between the convex portion 6 a of the cylinder and the base end portion 7 a of the piston 7. The first spring 12 biases the piston 7 toward the base end side. Note that there is a sufficient gap between the convex portion 6a of the cylinder and the neck portion 7b of the piston 7 for the fuel to pass therethrough. Further, there is a sufficient gap between the piston base end portion 7c and the wall surface of the cylinder 6 for the fuel to pass therethrough.

  A storage chamber 13 is formed at the distal end side of the metering chamber 9. The accommodation chamber 13 is connected to the metering chamber 9 by a communication path 20. Further, the storage chamber 13 communicates with the outside of the nozzle body 5 through the nozzle hole 4. A spherical valve element 14 and a second spring 15 that urges the valve element 14 toward the communication path 20 are accommodated in the accommodation chamber 13. The valve body 14 is urged by the second spring 15 to close the communication path 20. Such a valve body 14 corresponds to a valve body of the present invention, and the second spring 15 corresponds to an elastic body of the present invention.

  Further, the second fuel passage 11 is provided with a check valve 17 for preventing a back flow of fuel from the metering chamber 9 side to the switching valve 3. Further, a return passage 18 branches from between the switching valve 3 and the check valve 17 on the second fuel passage 11. The return passage 18 is provided with a relief valve 19 for preventing fuel from flowing backward from the return passage 18 side to the second fuel passage 11 side and for relieving the fuel. The relief valve 19 opens at a pressure lower than that of the valve body 14. Further, such a relief valve 19 prevents air from entering the second fuel passage 11.

  Next, the switching valve 3 will be described. The first fuel passage 10 and the second fuel passage 11 described above are connected to the switching valve 3. A third fuel passage 16 is connected to the switching valve 3. The third fuel passage 16 connects the switching valve 3 and a common rail (not shown). The switching valve 3 includes a state in which fuel is introduced from the common rail to the back pressure chamber 8, a state in which the back pressure chamber 8 and the metering chamber 9 are connected, and both the back pressure chamber 8 and the metering chamber 9 and the outside. This is a switching valve for switching between the shut-off state. Here, when both the back pressure chamber 8 and the metering chamber 9 are disconnected from the outside, the back pressure chamber 8 is disconnected from the common rail. At this time, the fuel in the back pressure chamber 8 and the fuel in the metering chamber 9 are maintained as they are. That is, the fuel does not increase or decrease.

  FIG. 2 is an explanatory diagram showing a schematic configuration of the switching valve 3. FIG. 2 (a1) is an explanatory view showing a state in which the connection between the back pressure chamber 8 and the outside is cut off, and the connection between the metering chamber 9 and the outside is cut off, and FIG. 2 (b1) shows the back pressure chamber. FIG. 2 (c1) shows a state in which the back pressure chamber 8 and the common rail are connected and fuel is introduced into the back pressure chamber 8. FIG. FIG. FIG. 2 (a2) is an explanatory diagram schematically showing the connection state of the path in the state of FIG. 2 (a1). FIG. 2 (b2) is an explanatory diagram schematically showing the connection state of the route in the state of FIG. 2 (b1), and FIG. 2 (c2) is the route in the state of FIG. 2 (c1). It is explanatory drawing which showed typically the connection state of.

  The switching valve 3 includes a first valve body 31, a second valve body 32, a third valve body 33, a third spring 34, and a fourth spring 35. These components are arranged in the order of the first valve body 31, the second valve body 32, the third spring 34, the third valve body 33, and the fourth spring 35 in the passage formed inside the switching valve 3. Yes. The first valve body 31 is a valve body that switches between allowing and blocking communication between the first fuel passage 10 connected to the back pressure chamber 8 side and the second fuel passage 11 connected to the metering chamber 9 side. The first valve body 31 is driven by a piezo actuator (not shown) and moves according to the expansion and contraction of the piezo actuator. The second valve body 32 is a spherical valve body that moves with the movement of the first valve body 31 and is a valve body that switches between allowing and blocking communication between the first fuel passage 10 and the second fuel passage 11. The third valve body 33 is a valve body that switches between allowing and blocking communication between the first fuel passage 10 connected to the back pressure chamber 8 side and the third fuel passage 16 connected to the common rail side. The third spring 34 is sandwiched between the second valve body 32 and the third valve body 33. The fourth spring 35 biases the third valve body 33 toward the second valve body 32. The spring constant of the fourth spring 35 is larger than the spring constant of the third spring 34.

  In a state where no voltage is applied to the piezo actuator, the state shown in FIG. The second valve body 32 is urged toward the first valve body 31 by the third spring 34 to block communication between the first fuel passage 10 and the second fuel passage 11. The third valve body 33 is urged toward the second valve body 32 by the fourth spring 35 to block communication between the first fuel passage 10 and the third fuel passage 16. That is, in the first fuel passage 10, the second fuel passage 11, and the third fuel passage 16, the fuel flow is blocked by the switching valve 3.

  Next, a case where a low voltage is applied to the piezo actuator will be described. When a low voltage is applied to the piezoelectric actuator, the state shown in FIG. In this case, the first valve body 31 moves to the second valve body 32 side by the piezoelectric actuator. At this time, the first valve body 31 presses the second valve body 32 against the third valve body 33 side. The second valve body 32 is pushed by the first valve body 31 with a force stronger than the urging force of the third spring 34. For this reason, the second valve body 32 moves to the third valve body 33 side and contacts the third valve body 33. The third valve body 33 is pushed by the second valve body 32. At this time, the biasing force of the second control spring 34 is stronger than the force by which the second valve body 32 pushes the third valve body 33. The communication between the first fuel passage 10 and the third fuel passage 16 is blocked. At this time, both the first valve body 31 and the second valve body 32 communicate with the first fuel passage 10 and the second fuel passage 11, and the first fuel passage 10 and the second fuel passage 11 communicate with each other. It becomes a state. That is, the back pressure chamber 8 and the metering chamber 9 of the fuel injection device 1 are in communication with each other.

  Next, when a higher voltage is applied to the piezo actuator than the state shown in FIG. 2 (b1), the state shown in FIG. 2 (c1) is obtained. In this case, the first valve body 31 further presses the second valve body 32 against the third valve body 33 side by the piezoelectric actuator. At the same time, the first valve body 31 blocks communication between the first fuel passage 10 and the second fuel passage 11. At this time, since the second valve body 32 presses the third valve body 33 with a force stronger than the urging force of the fourth spring 35, the third valve body 33 moves away from the first valve body 31 side. To do. Thus, the first fuel passage 10 and the third fuel passage 16 are in communication with each other. As a result, the fuel injection device 1 communicates the back pressure chamber 8 with the common rail, and enters the state where fuel is introduced into the back pressure chamber 8.

  Next, the operation of the fuel injection device 1 in each state of the switching valve 3 will be described. FIG. 3 is an explanatory view showing a state in which the injection by the fuel injection device 1 is completed. Here, the switching valve 3 is in the state shown in FIG. 2 (c <b> 1), that is, the state in which fuel is introduced from the common rail to the back pressure chamber 8. At this time, the piston 7 is located on the tip side. That is, since the fuel in the metering chamber 9 is ejected, the volume of the metering chamber 9 is almost empty. On the other hand, the inside of the back pressure chamber 8 is in a state where fuel is supplied from the common rail and filled with fuel. When the injection is thus completed, the switching valve 3 shifts to the state shown in FIG. 2B1, that is, the state in which the back pressure chamber 8 and the metering chamber 9 are communicated.

  FIG. 4 is an explanatory view showing an operating state of the fuel injection device 1 when the switching valve 3 is in a state of connecting the back pressure chamber 8 and the metering chamber 9. In such a state, the fuel is led out from the back pressure chamber 8 filled with high-pressure fuel toward the switching valve 3 side. At this time, receiving the biasing force of the first spring 12, the piston 7 starts to move toward the base end side. Thereby, the fuel discharged from the back pressure chamber 8 passes through the first fuel passage 10, the switching valve 3, and the second fuel passage 11 and is filled into the metering chamber 9. In such a metering state, when the pressure in the metering chamber 9 increases more than necessary, the relief valve is opened. Thereby, the pressure rise in the metering chamber 9 is suppressed, the closed state of the valve body 14 is maintained, and injection is suppressed.

  In this state, when the fuel required for injection is filled into the metering chamber 9, the switching valve 3 is in the state shown in FIG. 2 (a1), that is, between the back pressure chamber 8 and the metering chamber 9. The communication is cut off, and the state of the back pressure chamber 8 and the common rail is also cut off. FIG. 5 shows the operation state of the fuel injection device 1 when the switching valve 3 blocks communication between the back pressure chamber 8 and the metering chamber 9 and blocks communication between the back pressure chamber 8 and the common rail. It is explanatory drawing shown. At this time, the fuel in the back pressure chamber 8 and the metering chamber 9 is maintained as it is. That is, this state is a standby state until the fuel injection by the fuel injection valve 2.

  Next, when the fuel injection timing by the fuel injection valve 2 is reached, the switching valve 3 shifts to the state shown in FIG. 2C1, that is, the state in which fuel is introduced from the common rail to the back pressure chamber 8. FIG. 6 is an explanatory diagram showing the operating state of the fuel injection device 1 in a state where the switching valve 3 has shifted to a state where fuel is introduced into the back pressure chamber 8. When the switching valve 3 shifts to a state in which fuel is introduced into the back pressure chamber 8, fuel is supplied from the common rail into the back pressure chamber 8. Since the fuel is supplied into the back pressure chamber 8 in this way, the pressure in the back pressure chamber 8 is increased as compared with the inside of the metering chamber 9, so that the piston 7 starts to move toward the tip side. . Thus, when the piston 7 moves to the tip side, the volume of the metering chamber 9 decreases, and the pressure in the metering chamber 9 increases. Thus, when the pressure in the metering chamber 9 rises, the valve body 14 is opened, and the metering chamber 9 and the injection hole 4 communicate with each other. Thereby, the fuel in the metering chamber 9 is injected. As described above, the fuel for filling the metering chamber 9 is stored in the back pressure chamber 8 at the same time as the fuel in the metering chamber 9 is injected.

  Since the fuel injection device 1 separates the fuel injection step and the fuel metering step, the fuel injection device 1 is not affected by the pressure pulsation of the common rail during metering. In addition, since the fuel injection amount can be measured before the injection as compared with the conventional injection device that performs the metering simultaneously with the injection, the metering accuracy of the fuel to be injected is increased. In the conventional injector, the fuel injection amount is determined by the valve opening time. In addition, since the fuel is metered simultaneously with the injection, the fuel to be injected increases or decreases as the valve opening time increases. On the other hand, in the fuel injection device 1 of the present invention, the amount of fuel to be injected is adjusted in advance, so that fuel is not injected too much. Furthermore, since the fuel injection device 1 can adjust the injection amount between injections, the metering accuracy of the injected fuel is increased. For example, when the engine is driven at 4000 RPM, since the injection interval is 30 ms, the fuel required for injection can be metered within this time. Moreover, even if the moving speed of the valve body 14 is increased, the injection amount is not affected. Therefore, by increasing the moving speed of the valve body 14, high injection can be realized from the start of injection.

  Next, a second embodiment of the present invention will be described. FIG. 7 is an explanatory diagram showing a schematic configuration of the fuel injection device 51 of the present embodiment. The fuel injection device 51 of this embodiment includes a fuel injection valve 52 and a switching valve 3. The switching valve 3 has the same configuration as the switching valve 3 of the first embodiment.

  The fuel injection valve 52 includes a nozzle body 55. The nozzle body 55 is formed with a cylinder 56 different from the cylinder 6 of the first embodiment. As for the cylinder 56, the base end side 56b is formed in large diameter compared with the front end side 56a. The fuel injection valve 52 is provided with a piston 57 that slides in the cylinder 56. The piston 57 includes a small diameter portion 57 a and a large diameter portion 57 b, the small diameter portion 57 a is disposed on the distal end side 56 a of the cylinder 56, and the large diameter portion 57 b is disposed on the proximal end side 56 b of the cylinder 56. Such a piston 57 forms a back pressure chamber 58 on the proximal end side 56 b inside the cylinder 56, and forms a metering chamber 59 on the distal end side 56 a inside the cylinder 56. Further, a fifth spring 53 is disposed in a space 54 formed between the small diameter portion 57 a and the base end side 56 b of the cylinder 56. The fifth spring 53 is sandwiched between the large diameter portion 57 b of the piston 57 and the base end side 56 b of the cylinder 56, and urges the piston 57 toward the base end side of the fuel injection valve 52. In addition, a leak collection path 60 is connected to the space 54. In addition, since the other structure is the same as Example 1, about the component same as Example 1, the same reference number is attached | subjected in drawing and the detailed description is abbreviate | omitted.

  In such a fuel injection valve 52, the piston 57 includes a small diameter portion 57a and a large diameter portion 57b, and the pressure receiving area on the back pressure chamber 58 side of the piston 57 is wider than the pressure receiving area on the metering chamber 89 side. Thereby, the pressure of the fuel in the metering chamber 59 can be made higher than the pressure of the fuel in the back pressure chamber 58. At the time of injection by the fuel injection valve 52, the pressure in the back pressure chamber 58 is the common rail pressure. With such a configuration, the pressure in the metering chamber 59 is higher than the pressure in the common rail. For this reason, the fuel can be injected with a fuel injection pressure higher than that of the common rail.

  Next, Embodiment 3 of the present invention will be described. FIG. 8 is an explanatory view showing a schematic configuration of the fuel injection device 61 of the present embodiment. FIG. 9 is an explanatory diagram showing an enlarged front end portion of the fuel injection device 61. The fuel injection device 61 according to this embodiment includes a fuel injection valve 62 and a switching valve 3. The switching valve 3 has the same configuration as the switching valve 3 of the first embodiment.

  The fuel injection valve 62 includes a nozzle body 65. A cylinder 66 is formed inside the nozzle body 65. The cylinder 66 includes a distal end portion 66a, a central portion 66b having a larger diameter than the distal end portion 66a, and a proximal end portion 66c having a smaller diameter than the distal end portion 66a. A sheet portion 63 that is tapered toward the tip of the nozzle body 65 is formed on the tip of the cylinder 66. A nozzle hole 64 is formed on the tip side of the sheet portion 63, and the nozzle hole 65 communicates with the outside through the nozzle hole 64. Further, the fuel injection valve 62 is provided with a piston 67 and a valve body 74. The piston 67 slides in the cylinder 66. The piston 67 is formed in a cylindrical shape, and the valve body 74 is configured to slide on the inner peripheral side of the piston 67.

  The valve body 74 is a needle valve having a pointed tip side. The distal end side of the valve body 74 is seated on the seat portion 63 and closes the injection hole 64. Thereby, the fuel injection valve 62 stops fuel injection. The base end portion of the valve body 74 is slidably disposed on the base end portion 66 c of the cylinder 66. On the proximal end side of the valve body 74, a sixth spring 75 corresponding to the elastic body of the present invention urges the valve body 74 toward the distal end side and is held therebetween. A fuel passage 73 is formed inside the valve body 74. One end of the fuel passage 73 opens to the base end portion 66 c of the cylinder 66, and the other end opens to the base end side of the seat portion 63. Further, a check valve 77 for preventing the backflow of fuel from the outside of the valve body 74 to the fuel passage 73 is disposed at the end of the fuel passage 73 on the distal end side of the valve body 74.

  The piston 67 includes a small diameter portion 67a and a large diameter portion 67b having different outer diameters. The small diameter portion 67 a is disposed at the tip portion 66 a of the cylinder 66, and the large diameter portion 67 b is disposed at the center portion 66 b of the cylinder 66.

  The piston 67 and the valve body 74 form a back pressure chamber 68 at the central portion 66 b inside the cylinder 66, and form a metering chamber 69 at the tip 66 a inside the cylinder 66. Further, a seventh spring 72 is disposed in a space 70 formed between the small diameter portion 67 a of the piston 67 and the central portion 66 b of the cylinder 66. The seventh spring 72 is held between the large-diameter portion 67a of the piston 67 and the central portion 66b of the cylinder 66, and urges the piston 67 toward the base end side. The large-diameter portion 67b of the piston 67 is formed with a passage connecting the base end side and the distal end side of the large-diameter portion 67b, and fuel flows between the back pressure chamber 68 and the space 70. can do.

  The back pressure chamber 68 and the switching valve 3 are connected by the first fuel passage 10. The base end portion 66 c of the cylinder 66 and the switching valve 3 are connected to the second fuel passage 11. When the first fuel passage 10 and the second fuel passage 11 communicate with each other depending on the state of the switching valve 3, the back pressure chamber is passed through the first fuel passage 10, the second fuel passage 11, and the fuel passage 73 of the valve body 74. 68 fuels are filled into the metering chamber 69. The first fuel passage 10, the second fuel passage 11, and the fuel passage 73 communicate with each other to constitute the fuel passage of the present invention. Further, a return passage 18 is connected to the base end portion 66c of the cylinder 66, and unnecessary fuel can be returned.

  In addition, since the other structure is the same as Example 1, about the component same as Example 1, the same reference number is attached | subjected in drawing and the detailed description is abbreviate | omitted.

  Next, the operation of the fuel injection device 61 will be described. FIG. 10 is an explanatory view showing the fuel injection device 61 immediately after fuel injection. FIG. 11 is an explanatory view showing the fuel injection device 61 in a state where the back pressure chamber 68 and the metering chamber 69 are in communication. FIG. 12 is an explanatory view showing the fuel injection device 61 in standby for injection. FIG. 13 is an explanatory view showing a fuel injection device 61 during fuel injection.

  In the fuel injection device 61 shown in FIG. 10, the metering chamber 69 is almost empty. On the other hand, the back pressure chamber 68 is filled with fuel. When the switching valve 3 shifts from this state to a state in which the back pressure chamber 68 and the metering chamber 69 communicate with each other, the fuel injection device 61 enters the state shown in FIG. When the fuel injection device 61 is in the state shown in FIG. 11, the piston 57 starts to move to the proximal end side by the urging force of the seventh spring 72, and the fuel in the back pressure chamber 68 is transferred to the first fuel passage 10 and the second fuel passage 11. The metering chamber 69 is filled through the base end portion 66 c and the fuel passage 73. When the fuel to be injected next time into the metering chamber 69 is metered, the switching valve 3 shuts off the communication between the back pressure chamber 68 and the metering chamber 69 and also shuts off the communication between the back pressure chamber 68 and the common rail. Transition to the completed state. As a result, the fuel injection device 61 is in the state shown in FIG. In FIG. 12, the fuel injection device 61 maintains this state until the time of fuel injection. Next, at the fuel injection timing, the switching valve 3 shifts to a state where fuel is introduced into the back pressure chamber 68. As a result, the fuel injection device 61 is in the state shown in FIG. In this state, fuel is supplied from the common rail into the back pressure chamber 68. As a result, the pressure on the back pressure chamber 68 side increases, and the piston 67 moves to the tip side. For this reason, the volume of the metering chamber 69 decreases, and the pressure in the metering chamber 69 increases. With this increase in pressure, the valve body 74 moves to the proximal end side, and the nozzle hole 64 is opened. As a result, the fuel in the metering chamber 69 is injected from the injection hole 64. Thus, at the same time as the fuel in the metering chamber 69 is injected, the fuel for filling the metering chamber 69 next is stored in the back pressure chamber 68.

  In the fuel injection device 61 of this embodiment, the valve body 74 is seated on the seat portion 63 and closes the injection hole 64. For this reason, compared with the fuel injection device 1 of the first embodiment, the leakage of fuel from the injection hole 64 when the fuel injection is stopped can be suppressed, and the generation of HC can be reduced. The fuel injection device 61 of the present embodiment achieves both ensuring of metering accuracy and reduction of HC generation at light loads.

  Next, a fourth embodiment of the present invention will be described. FIG. 14 is an explanatory diagram showing a schematic configuration of the fuel injection device 81. The fuel injection device 81 has substantially the same configuration as the fuel injection device 1 of the first embodiment. However, the fuel injection device 81 is different from the fuel injection valve 1 of the first embodiment in that a lift sensor 82 is disposed on the base end side of the piston 7. This lift sensor 82 corresponds to the measuring means of the present invention. Such a lift sensor 82 measures the position of the piston 7. In addition, since the other structure is the same as Example 1, about the component same as Example 1, the same reference number is attached | subjected in drawing and the detailed description is abbreviate | omitted.

  Next, other configurations of the fourth embodiment will be described. FIG. 15 is an explanatory diagram showing a schematic configuration of the fuel injection device 91. The fuel injection device 91 has substantially the same configuration as the fuel injection device 1 of the first embodiment. However, the fuel injection device 91 is different from the fuel injection device 1 of the first embodiment in that it includes a piston 92 instead of the piston 7 of the first embodiment and a gap sensor 93 in the cylinder 6. It is different. The piston 92 is composed of a distal end side piston portion 92a, a neck portion 92b, and a proximal end side piston portion 92c. The front end side piston part 92a is slidably disposed on the front end side of the convex part 6a of the cylinder 6 so that it can slide on the cylinder 6, and the contact surface between the front end side piston part 92a and the cylinder 6 is sealed. Further, the base end side piston portion 92c is arranged to be slidable on the cylinder 6 on the base end side with respect to the convex portion 6a of the cylinder 6, and the contact surface between the base end side piston portion 92c and the cylinder 6 is sealed. . Such a piston 92 forms a back pressure chamber 98 on the proximal end side in the cylinder 6 and forms a metering chamber 99 on the distal end side in the cylinder 6. Further, a low pressure chamber 94 is formed between the front end side piston portion 92a and the base end side piston portion 92b. Since the back pressure chamber 98 and the metering chamber 99 are the same as the back pressure chamber 8 and the metering chamber 9 of the first embodiment, detailed description thereof is omitted here. The inside of the low pressure chamber 94 is maintained at a lower pressure than the back pressure chamber 98 and the metering chamber 99. A gap sensor 93 is disposed on the tip side of the convex portion 6 a in the low pressure chamber 94. This gap sensor 93 corresponds to the measuring means of the present invention. The gap sensor 93 measures the distance from the front end side piston portion 92a and measures the position of the piston. In addition, since the other structure is the same as Example 1, about the component same as Example 1, the same reference number is attached | subjected in drawing and the detailed description is abbreviate | omitted.

  Next, another configuration different from the above configuration will be described. FIG. 16 is an explanatory diagram showing a schematic configuration of the fuel injection device 101. The fuel injection device 101 has substantially the same configuration as the fuel injection device 1 of the first embodiment. However, the fuel injection device 101 is different from that of the first embodiment in that the magnet 102 is embedded in the piston portion 7a of the piston 7 of the first embodiment and the detection coil 103 that detects the magnetic flux of the magnet. This is different from the apparatus 1. A combination of the magnet 102 and the detection coil 103 corresponds to the detection means of the present invention. By embedding the magnet 102 in the piston 7, the magnetic flux measured in the detection coil 103 changes as the piston 7 moves. Based on such a change in magnetic flux, the position of the piston 7 is measured. In addition, since the other structure is the same as Example 1, about the component same as Example 1, the same reference number is attached | subjected in drawing and the detailed description is abbreviate | omitted.

  The fuel injection devices 81, 91, 101 of the present embodiment described above can accurately grasp the fuel amount filled in the metering chamber 9 by accurately measuring the position of the piston 7 or the piston 92. . Thereby, the metering accuracy is further improved.

  The above-described embodiments are merely examples for carrying out the present invention, and the present invention is not limited thereto. Various modifications of these embodiments are within the scope of the present invention. It is apparent from the above description that various other embodiments are possible within the scope.

It is explanatory drawing which showed schematic structure of the fuel-injection apparatus of Example 1. FIG. It is explanatory drawing which showed schematic structure of the switching valve, Comprising: (a1) is the description which showed the state which also interrupted | blocked communication with a back pressure chamber and a common rail while interrupting | blocking communication with a back pressure chamber and a metering chamber (A2) is an explanatory view schematically showing the path connection state in the state of (a1), and (b1) shows a state in which the back pressure chamber and the metering chamber are communicated with each other. It is explanatory drawing shown, (b2) is explanatory drawing which showed typically the connection state of the path | route at the time of the state of (b1), (c1) connects a back pressure chamber and a common rail, It is explanatory drawing which showed the state which introduce | transduces fuel into a back pressure chamber, (c2) is explanatory drawing which showed typically the connection state of the path | route at the time of the state of (c1). It is explanatory drawing which showed the fuel-injection apparatus of Example 1 immediately after fuel injection. It is explanatory drawing which showed the fuel-injection apparatus of Example 1 of the state which connected the back pressure chamber and the metering chamber. It is explanatory drawing which showed the fuel-injection apparatus of Example 1 in the injection standby. It is explanatory drawing which showed the fuel-injection apparatus of Example 1 injecting fuel. It is explanatory drawing which showed schematic structure of the fuel-injection apparatus of Example 2. FIG. It is explanatory drawing which showed schematic structure of the fuel-injection apparatus of Example 3. FIG. It is explanatory drawing which expanded and showed the front-end | tip part of the fuel-injection apparatus of Example 3. FIG. It is explanatory drawing which showed the fuel-injection apparatus of Example 3 immediately after fuel injection. It is explanatory drawing which showed the fuel-injection apparatus of Example 3 of the state which connected the back pressure chamber and the metering chamber. It is explanatory drawing which showed the fuel-injection apparatus of Example 3 in injection waiting. It is explanatory drawing which showed the fuel-injection apparatus of Example 3 injecting fuel. It is explanatory drawing which showed an example of schematic structure of the fuel-injection apparatus of Example 4. FIG. It is explanatory drawing which showed schematic structure of the other fuel-injection apparatus of Example 4. FIG. It is explanatory drawing which showed schematic structure of the further another fuel-injection apparatus of Example 4. FIG.

Explanation of symbols

1, 51, 61, 81, 91, 101 Fuel injection device 2, 52, 62 Fuel injection valve 3 Switching valve 4, 64 Injection hole 5, 55, 65 Nozzle body 6, 56, 66 Cylinder 7, 57, 67, 92 Piston 8, 58, 68, 98 Back pressure chamber 9, 59, 69, 99 Metering chamber 10 First fuel passage 11 Second fuel passage 13 Storage chamber 14, 74 Valve body 15 Second spring 17 Check valve 18 Return passage DESCRIPTION OF SYMBOLS 19 Relief valve 20 Communication path 63 Seat part 73 Fuel path 75 Sixth spring 82 Lift sensor 93 Gap sensor 102 Magnet 103 Detection coil

Claims (8)

A nozzle body with a nozzle hole drilled at the tip;
A piston that is housed inside the nozzle body, forms a back pressure chamber on the proximal end side inside the nozzle body, and forms a metering chamber on the distal end side;
A fuel passage that allows or blocks communication between the back pressure chamber and the metering chamber;
A valve element that opens as the piston moves by introducing fuel from outside into the back pressure chamber;
A fuel injection valve comprising: The fuel injection valve according to claim 1, wherein
A storage chamber that is formed on the tip side of the metering chamber in the nozzle body, and stores the valve body;
A communication path connecting the storage chamber and the metering chamber;
An elastic body that urges the valve body toward the communication path to close the communication path;
A fuel injection valve comprising: The fuel injection valve according to claim 1, wherein
The piston is formed in a cylindrical shape,
The valve body is a needle valve that is slidably housed inside the piston and closes the nozzle hole,
A fuel injection valve, wherein the fuel passage is formed in the valve body. The fuel injection valve according to claim 1, wherein
The fuel injection valve, wherein a pressure receiving area on the back pressure chamber side of the piston is wider than a pressure receiving area on the metering chamber side. The fuel injection valve according to claim 1, wherein
A fuel injection valve comprising a check valve in the fuel passage. The fuel injection valve according to claim 1, wherein
A return passage connected to the fuel passage;
A relief valve disposed in the return passage;
A fuel injection valve comprising: The fuel injection valve according to claim 1, wherein
A fuel injection valve comprising measuring means for measuring the amount of fuel in the metering chamber. A fuel injection valve according to any one of claims 1 to 7,
A state in which fuel is introduced into the back pressure chamber from the outside of the fuel injection valve, a state in which the back pressure chamber and the metering chamber are connected, and both the back pressure chamber and the metering chamber and the outside A fuel injection device comprising switching means for switching between a state where communication is cut off.

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