JP2010255425A - Fuel injection valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection valve improved in the detection accuracy of an injection state in the fuel injection valve including a fuel pressure sensor for detecting the fuel injection state. <P>SOLUTION: The outer peripheral surface of a needle 30 is formed with a plurality of guides 30b sliding with the inner peripheral surface of a body 20 and regulating the movement of the needle 30 in a radial direction, and a communication passage R2 (inter-guide passage) for supplying fuel to a nozzle port 22 is formed between the plurality of guide portions 30b. An inter-seat guide passage R1 for supplying fuel to the nozzle port 22 is formed between the inner peripheral surface of the body 20 and portions of the outer peripheral surface of the needle 30, the upstream of the seat surface and the downstream of the guides 30b. A sensor element 80 (fuel pressure sensor) is attached to the outer wall surface 20a of a portion (reservoir chamber 20b) forming the inter-seat guide passage R1 of the nozzle body 20, and thus the fuel pressure of the inter-seat passage R1 is detected. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a fuel injection valve that is mounted on an internal combustion engine and injects fuel for combustion from an injection hole.

  In order to accurately control the output torque and the emission state of the internal combustion engine, it is important to accurately control the injection state such as the injection start timing and the injection amount of the fuel injected from the fuel injection valve. Therefore, conventionally, there has been proposed a technique for detecting an actual injection state by detecting the pressure of fuel that fluctuates with the injection. For example, the actual injection start time can be detected by detecting the time when the fuel pressure starts to decrease with the start of injection, or the actual injection end time can be determined by detecting the time when the increase in fuel pressure has stopped with the end of injection. Or detected (see Patent Documents 1 to 3).

  When detecting such fluctuations in fuel pressure, the fuel pressure sensor (rail pressure sensor) installed directly on the common rail (accumulation vessel) buffers the fuel pressure fluctuation caused by injection in the common rail. Variation cannot be detected. Therefore, in the inventions described in Patent Documents 1 to 3, by mounting the fuel pressure sensor on the fuel injection valve, it is intended to detect the fuel pressure fluctuation before the fuel pressure fluctuation caused by the injection is buffered in the common rail. .

JP 2008-144749 JP 2009-57926 A JP 2009-57927 A

  However, although Patent Documents 1 to 3 disclose that the fuel pressure sensor is mounted on the fuel injection valve, the details of the mounting position are not disclosed. As a result of studies by the present inventors, it has been found that the detection accuracy of the injection state varies depending on the mounting position of the fuel pressure sensor.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a fuel injection valve provided with a fuel pressure sensor for detecting an injection state of fuel, and to improve the detection accuracy of the injection state. To provide a valve.

  Hereinafter, means for solving the above-described problems and the operation and effects thereof will be described.

  The invention according to claim 1 includes a body having a nozzle hole formed at a tip thereof, and a needle housed inside the body, and a seat surface formed on the needle is formed on a seating surface formed inside the body. In the fuel injection valve that opens and closes the nozzle hole by being seated or separated, a guide portion that slides on the inner peripheral surface of the body and restricts the radial movement of the needle on the outer peripheral surface of the needle However, a plurality of guide passages for supplying fuel to the nozzle holes are formed between the plurality of guide portions. A seat guide for supplying fuel to the nozzle hole between a portion of the outer peripheral surface of the needle on the upstream side of the seat surface and the downstream side of the guide portion and the inner peripheral surface of the body An inter-passage is formed, and a fuel pressure sensor arranged to detect a fuel pressure (fuel pressure) in the inter-sheet guide passage is provided.

  Hereinafter, the effects of the present invention will be described in comparison with Comparative Configuration Examples 1 to 3 configured against the present invention.

  For example, in the case of the configuration (comparative configuration example 1) for detecting the fuel pressure of the seat portion passage formed between the seating surface and the seat surface, contrary to the above-described invention, the following problem occurs.

  That is, when the lift amount of the needle is small, such as immediately after the needle is separated from the seating surface or just before seating, the gap between the seat surface of the needle and the seating surface of the body (the seat portion passage) is small. As a result, fuel is throttled in the seat portion passage. Then, the pressure fluctuation generated in the nozzle hole is attenuated in the seat portion passage. However, when the seat portion passage is sufficiently large, the attenuation hardly occurs. In other words, since the state changes according to the lift amount of the needle and changes to the state where it is not restricted, the magnitude of the attenuation also changes according to the lift amount, so that the detection accuracy of the injection state decreases.

  On the other hand, according to the present invention, since the fuel pressure sensor is arranged so as to detect the fuel pressure of the passage between the sheet guides located on the upstream side of the seat surface, compared with the comparative configuration example 1 that detects the fuel pressure of the seat portion passage, The fuel pressure can be detected at a location where the change in fuel pressure according to the lift amount is suppressed. Therefore, the detection accuracy of the injection state can be improved.

  Further, for example, in the case of the configuration (comparative configuration example 2) that detects the fuel pressure in the inter-guide passage contrary to the above-described invention, the following problem occurs.

  That is, the passage cross-sectional area of the inter-guide passage is difficult to ensure a large passage cross-sectional area as compared to the inter-sheet guide passage, and fuel is throttled in the inter-guide passage. Then, the pressure fluctuation generated in the nozzle hole is attenuated in the passage between the guides. Therefore, the pressure fluctuation in the passage between the guides differs from the pressure fluctuation in the nozzle hole actually generated. The accuracy of detection decreases.

  On the other hand, according to the present invention, the fuel pressure sensor is arranged so as to detect the fuel pressure of the passage between the sheet guides located on the downstream side of the guide portion. Therefore, compared with the comparative configuration example 2 that detects the fuel pressure of the passage between the guides, A pressure fluctuation close to the state of pressure fluctuation at the nozzle hole can be detected. Therefore, the detection accuracy of the injection state can be improved.

  Further, for example, in the case of the configuration (comparative configuration example 3) in which the fuel pressure on the upstream side of the inter-guide passage is detected contrary to the above invention, the fuel pressure fluctuation generated in the nozzle hole is propagated to the upstream side of the inter-guide passage. The time required for the injection becomes a propagation delay (time lag), and the detection accuracy of the injection state decreases. On the other hand, according to the present invention, since the fuel pressure in the passage between the sheet guides located on the downstream side of the guide portion is detected, the time lag can be reduced and the detection accuracy of the injection state can be improved.

  According to a second aspect of the present invention, the fuel pressure sensor is disposed on a side surface portion of the needle located in the passage between the sheet guides. In the third aspect of the present invention, the seat guide is included in the body. The fuel pressure sensor is arranged on the inner wall surface of the portion forming the inter-passage.

  According to these inventions, the fuel pressure sensor can be easily arranged to detect the fuel pressure in the passage between the seat guides. In particular, the sensing part of the fuel pressure sensor can be brought into direct contact with the fuel in the passage between the seat guides, which is advantageous in terms of improving the detection accuracy of the fuel pressure.

  As a sensing part of such a fuel pressure sensor, a pressure detection element (for example, a piezoelectric element) arranged so as to be exposed in the passage between the sheet guides is given as a specific example as described in claim 4.

  The invention according to claim 5 is characterized in that an insertion hole extending in the axial direction of the needle is formed in the needle, and the fuel pressure sensor is disposed in a portion of the insertion hole located in the passage between the seat guides. And

  According to the present invention, the fuel pressure sensor can be easily arranged to detect the fuel pressure in the passage between the seat guides. In particular, according to the above invention, the fuel pressure sensor can be arranged outside the passage between the seat guides. Therefore, when the wiring for outputting the detection signal is provided in the fuel pressure sensor, the wiring can be arranged in the insertion hole. Wiring paths can be easily secured. That is, when the fuel pressure sensor is arranged in the passage between the sheet guides as in the second and third aspects, the wiring route must be formed so as to take out the wiring from the passage between the sheet guides, resulting in a complicated structure. . On the other hand, according to the above invention in which the fuel pressure sensor can be arranged outside the passage between the seat guides, the wiring path can be easily secured.

  As a sensing part of such a fuel pressure sensor, a strain detection element (for example, a strain gauge) for detecting the amount of elastic deformation generated in the side wall part of the insertion hole can be cited as a specific example.

  The invention according to claim 7 is characterized in that the fuel pressure sensor is arranged on an outer wall surface of a portion of the body located in the passage between the sheet guides.

  According to this invention, it is possible to easily realize the arrangement of the fuel pressure sensor so as to detect the fuel pressure in the passage between the sheet guides. Particularly, since the fuel pressure sensor can be disposed outside the passage between the seat guides according to the above invention, when the wiring for outputting the detection signal is provided in the fuel pressure sensor, the wiring can be disposed along the outer surface of the body. The wiring path can be easily secured.

  As a sensing part of such a fuel pressure sensor, a specific example is a strain detection element (for example, a strain gauge) that detects an elastic deformation amount generated in a portion of the body that forms the passage between the sheet guides. As mentioned.

  The invention according to claim 9 is characterized in that the fuel pressure sensor has a transmission means for outputting and transmitting a detection signal wirelessly.

  According to this, it is possible to make it unnecessary to secure a wiring route that is necessary when the detection signal is transmitted by wire through the above-described wiring, and it is possible to easily realize the placement of the fuel pressure sensor in a narrow place. In particular, when the fuel pressure sensor is disposed in the passage between the sheet guides as in the second and third aspects, the above-described effect that it is not necessary to secure the wiring path is preferably exhibited.

1 is an overall cross-sectional view of a fuel injection valve according to a first embodiment of the present invention. The enlarged view of FIG. The enlarged view of FIG. AA sectional drawing of FIG. Sectional drawing of the fuel injection valve concerning 2nd Embodiment of this invention. Sectional drawing of the fuel injection valve concerning 3rd Embodiment of this invention. Sectional drawing of the fuel injection valve concerning 4th Embodiment of this invention. The electric circuit diagram which shows the system which carries out radio transmission / reception of the detection signal by a sensor element in 5th Embodiment of this invention. The electrical circuit diagram which shows the system which carries out radio transmission / reception of the detection signal by a sensor element in 6th Embodiment of this invention.

  Embodiments in which a fuel injection valve according to the present invention is applied to a common rail fuel injection system of a diesel engine (internal combustion engine) mounted on a vehicle will be described below with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other are denoted by the same reference numerals in the drawings, and the description of the same reference numerals is used.

(First embodiment)
1 is an overall cross-sectional view of the fuel injection valve 10, and FIG. 2 is an enlarged view of FIG. The fuel injection valve 10 is inserted and mounted in a cylinder head (not shown) of the engine, and directly injects fuel supplied from a common rail into each cylinder of the engine.

  First, the overall structure of the fuel injection valve 10 will be described with reference to FIG. The fuel injection valve 10 includes a nozzle body 20, a needle 30, a holder body 40, an orifice plate 50, an electromagnetic unit 60, and the like.

  The nozzle body 20 is fixed to the lower side (injection hole side) of the holder body 40 with the retaining nut 11 via the orifice plate 50. The nozzle body 20 is formed with a guide hole 21 (needle accommodating chamber) for slidably accommodating the needle 30 and an injection hole 22 for injecting fuel when the needle 30 is lifted up. Hereinafter, the nozzle hole 20 side (lower side in FIG. 1) is referred to as “lower side”, and the opposite side (upper side in FIG. 1) of the nozzle hole 22 is referred to as “upper side”.

  The guide hole 21 is drilled from the upper end surface of the nozzle body 20 toward the tip of the nozzle body 20, and a high-pressure passage 23 that guides high-pressure fuel to the injection hole 22 through a gap between the inner peripheral surface of the guide hole 21 and the outer peripheral surface of the needle 30. Is formed. Further, a fuel reservoir chamber 24 in which the inner diameter of the nozzle body 20 is enlarged is formed in the middle of the guide hole 21. The high-pressure passage 23 (guide hole 21) is connected to a high-pressure passage 51 formed in the orifice plate 50 with an upstream end opened to the upper end surface of the nozzle body 20.

  A conical seating surface 221 (see FIG. 3) is formed at the tip of the high-pressure passage 23 in the inner peripheral surface of the nozzle body 20, and a seat surface 331 (see FIG. 3) seated on the seating surface 221 at the tip of the needle 30. Reference) is formed. When the seat surface 331 is seated on the seating surface 221, the needle 30 blocks and blocks the high-pressure passage 23 leading to the nozzle hole 22.

  A cylindrical cylinder 25 is disposed in the guide hole 21, and a spring that presses the needle 30 in the valve closing direction (downward in FIG. 1) between the lower end surface of the cylinder 25 and the upper end surface of the needle 30. 26 is arranged. A back pressure chamber 27 is formed on the inner peripheral surface of the cylinder 25 to apply a high pressure fuel pressure as a back pressure to the upper end surface of the needle 30. This back pressure biases the needle 30 in the valve closing direction (downward in FIG. 1). Further, the pressure of the high-pressure fuel in the fuel reservoir 24 urges the needle 30 in the valve opening direction (upward in FIG. 1).

  A pipe joint 41 is provided at the upper end portion of the holder body 40, and high-pressure fuel is supplied from the common rail through a fuel pipe (not shown) connected to the pipe joint 41. A filter (not shown) for filtering fuel is disposed in the internal passage of the pipe joint 41.

  Inside the holder body 40, a high-pressure passage 42 for guiding the high-pressure fuel introduced into the pipe joint 41 to the high-pressure passage 23 of the nozzle body 20 via the high-pressure passage 51 of the orifice plate 50, and the electromagnetic unit 60 are disposed. An accommodation hole 43 and the like are formed. The high pressure passage 42 and the accommodation hole 43 have a shape extending in the axial direction of the fuel injection valve 10 (vertical direction in FIG. 1). The “axial direction” referred to in the present specification is the longitudinal direction of the fuel injection valve 10, and is also the insertion direction of the fuel injection valve 10 inserted and mounted in the cylinder head.

  In the present embodiment, the electromagnetic unit 60 and the high-pressure passage 42 are laid out in a direction perpendicular to the axial direction of the holder body 40 (left-right direction in FIG. 1).

  As shown in FIG. 2, the orifice plate 50 is formed with an inflow passage 52 through which high-pressure fuel flows from the high-pressure passage 51 to the back pressure chamber 27 and an outflow passage 53 through which the high-pressure fuel flows out from the back pressure chamber 27 to the low pressure side. Yes. An inlet orifice 52a is formed in the inflow passage 52, and an outlet orifice 53a is formed in the outflow passage 53.

  The electromagnetic unit 60 includes a stator 63 having an electromagnetic coil 62, an armature 64 that is movable facing the stator 63, a ball valve 65 (control valve) that moves integrally with the armature 64 and opens and closes the outlet orifice 53a. It is prepared for.

  A resin connector housing 70 (see FIG. 1) is attached to the upper portion of the holder body 40, and a drive terminal 72 (see FIG. 1) and an electromagnetic coil 62 provided on the connector housing 70 are electrically connected by lead wires 73. Connected.

  When the electromagnetic coil 62 is energized, the armature 64 is magnetized by the generated magnetic flux and is attracted to the stator 63 by the magnetic attraction force to move. The spring 66 (elastic member) housed in the central portion of the stator 63 urges the armature 64 in the direction in which the ball valve 65 is closed (downward in FIG. 2).

  An annular groove 56 is formed in the lower end surface of the orifice plate 50, and the high pressure passage 51 of the orifice plate 50 and the high pressure passage 23 of the nozzle body 20 communicate with each other through the groove 56. In the middle of the high-pressure passage 23, a gap 25 a between the outer peripheral surface of the cylinder 25 and the inner peripheral surface of the nozzle body 20, a spring storage portion 23 a that stores the spring 26, and a chamfered portion 30 a that is formed on the side surface of the needle 30. , A fuel reservoir chamber 24, a first fuel passage R1 and a second fuel passage S (see FIG. 3) described below, and the like exist.

  FIG. 3 is an enlarged view of the tip shape of the needle 30 and the like, and shows a state where the needle 30 is seated on the seating surface 221 and closed. The needle 30 includes a needle cylinder portion 31 extending in the axial direction (vertical direction in FIG. 3), a first cone portion 32 extending in the axial direction from the downstream end of the needle cylinder portion 31 and gradually reducing the outer diameter, and a first cone portion. A second conical portion 33 extending in the axial direction from the downstream end of 32 and gradually reducing the outer diameter, and a third conical portion 34 extending in the axial direction from the downstream end of the second conical portion 33 and gradually reducing the outer diameter. It is configured with.

  The nozzle body 20 includes a body cylindrical portion 210 that faces the needle column portion 31 and a body tip portion 220 that extends in the axial direction from the downstream end of the body cylindrical portion 210 and gradually reduces the inner diameter. The internal conical surface of the body tip 220 functions as the seating surface 221 described above. The conical surface of the second conical portion 33 (portion to which the halftone dot in FIG. 3 is attached) functions as the sheet surface 331 described above.

  An annular first fuel passage R1 extending in the axial direction is formed between the inner peripheral surface 211 of the body cylindrical portion 210 and the outer peripheral surface 311 of the needle cylindrical portion 31. Between the inner peripheral surface of the body front end portion 220 including the seating surface 221 and the outer peripheral surfaces of the first conical portion 32 and the second conical portion 33 of the needle 30, from the downstream end of the first fuel passage R <b> 1 to the annular inner side. An extending annular second fuel passage S is formed. Further, a sack chamber 222 formed between the outer peripheral surface of the third conical portion 34 is provided on the downstream side of the seating surface 221 in the body front end portion 220. The sac chamber 222 functions to collect fuel distributed in an annular shape in the second fuel passage S. A plurality of nozzle holes 22 are formed in a portion of the body leading end 220 where the sac chamber 222 is formed. Therefore, the fuel in the second fuel passage S is collected in the sac chamber 222 and then injected from the plurality of injection holes 22.

  4 is a cross-sectional view taken along the line AA of FIG. 2, showing a state where the needle 30 is separated from the seating surface 221 and opened, and a plurality of chamfered portions 30a are formed on the side surface of the needle 30 (in the example of FIG. 4). 3 sides) are formed. A portion of the outer peripheral surface of the needle 30 where the chamfered portion 30 a is not formed functions as a guide portion 30 b that slides on the inner peripheral surface of the nozzle body 20 and restricts the needle 30 from moving in the radial direction. A communication path R <b> 2 is formed between the inner peripheral surface of the nozzle body 20 and the chamfered portion 30 a so that the spring accommodating portion 23 a communicates with the fuel reservoir chamber 24.

  This communication path R2 corresponds to an “inter-guide path”. That is, it can be said that a plurality of guide portions 30b are formed at equal intervals in the circumferential direction of the outer peripheral surface of the needle 30, and a communication path R2 (inter-guide passage) is formed between the plurality of guide portions 30b.

  Regarding the fuel cross-sectional area, the sum of the cross-sectional areas of the communication passage R2 by the chamfered portion 30a is the cross-sectional area of the fuel reservoir chamber 24, the cross-sectional area of the first fuel passage R1, and the needle 30 is separated from the seating surface 221. Thus, it is set to be smaller than both the passage sectional area of the second fuel passage S when the lift amount is maximum and the passage sectional area of the sac chamber 222. Of these passage cross-sectional areas, the passage cross-sectional area of the fuel reservoir chamber 24 is set to be the largest.

  Returning to the description of FIG. 2, a sensor element 80 (fuel pressure sensor) is attached to the outer wall surface 20 a of the nozzle body 20 located in the fuel reservoir chamber 24 (hereinafter referred to as “reservoir chamber portion 20 b”). . The first fuel passage R1 including the fuel reservoir chamber 24 corresponds to a “sheet guide passage”. That is, the first fuel passage R1 communicates with the upstream side of the second fuel passage S formed by the seat surface 331, and communicates with the downstream side of the communication passage R2 formed by the chamfered portion 30a. The most upstream portion of the first fuel passage R1 functions as the fuel reservoir 24.

  The sensor element 80 converts the magnitude of strain generated in the reservoir chamber 20b into an electrical signal and outputs it as a pressure detection value. In this embodiment, a strain gauge (strain detection element) is used as the sensor element 80. Adopted. This strain gauge is fixed by being sealed (baked) with a glass member (not shown) in a state of being disposed on the outer wall surface 20a of the reservoir 20b.

  Therefore, the sensor element 80 detects the magnitude of the strain (elastic deformation amount) of the reservoir chamber 20b generated according to the fuel pressure of the fuel reservoir 24, so that the fuel pressure of the fuel reservoir 24 is detected. Become. The fuel injection valve 10 is equipped with a circuit for amplifying a detection signal output from the sensor element 80, a filtering circuit for removing noise superimposed on the detection signal, a circuit for applying a voltage to the sensor element 80, and the like. These circuits (not shown) may be installed in the connector housing 70, for example. The detection signal output from the sensor element 80 is processed by an amplifier circuit or a filtering circuit, and then output from the sensor terminal 71 (see FIG. 1) to an external ECU or the like.

  A lead wire 81 that electrically connects various circuits such as an amplifier circuit and the sensor element 80 is disposed along the outer peripheral surface of the nozzle body 20 and the holder body 40 from the reservoir 20b to the connector housing 70.

  The thickness of the reservoir 20b is formed thinner than the upstream and downstream portions of the reservoir 20b. As a result, as described above, the largest passage cross-sectional area of the fuel reservoir 24 is realized without increasing the outer diameter of the nozzle body 20 in the reservoir 20b.

  Next, the operation of the fuel injection valve 10 will be described.

  When the energization of the electromagnetic coil 62 is stopped, the ball valve 65 closes the outlet orifice 53a, so that the force that biases the needle 30 in the valve closing direction (the force due to the fuel pressure in the back pressure chamber 27). + The urging force of the spring 26) is larger than the force that pushes up the needle 30 in the valve opening direction (lift force due to the fuel pressure in the fuel reservoir chamber + lift force due to the fuel pressure applied to the first to third conical portions 32, 33, and 34). . As a result, the seat surface 331 of the needle 30 is seated on the seating surface 221, and the fuel is not injected by blocking between the high-pressure passage 23 and the injection hole 22.

  When the electromagnetic coil 62 is energized, the armature 64 is attracted to the magnetized stator 63, and the armature 64 moves toward the stator 63 against the biasing force of the spring 66, so that the ball valve 65 is moved back. In response to the fuel pressure in the pressure chamber 27, the outlet orifice 53a is opened. Therefore, the high pressure fuel in the back pressure chamber 27 is opened to the low pressure side through the outlet orifice 53a. Since both the orifices 53a and 52a are set so that the outflow amount from the outlet orifice 53a with respect to the back pressure chamber 27 is larger than the inflow amount from the inlet orifice 52a, the back pressure chamber is opened when the ball valve 65 is opened as described above. 27 fuel pressure decreases. As a result, the needle 30 is lifted when the force that pushes the needle 30 in the valve opening direction (lift force due to the fuel pressure in the fuel reservoir chamber 24) exceeds the force that biases the needle 30 in the valve closing direction. Therefore, the high-pressure fuel supplied from the common rail to the fuel injection valve 10 is injected from the injection hole 22 through the high-pressure passages 42, 51, 23, the communication passage R 2, the first fuel passage R 1, the second fuel passage S, and the sac chamber 222. The

  According to the embodiment described in detail above, the following effects can be obtained.

  (1) If the sensor element 80 is arranged so as to detect the fuel pressure in the second fuel passage S contrary to the present embodiment, the following problem occurs. That is, when the lift amount of the needle 30 is small, the fuel is throttled in the seat portion passage due to the small gap (seat portion passage) between the seat surface 331 and the seating surface 221. The generated pressure fluctuation is attenuated in the seat portion passage. However, when the lift amount is sufficiently large, the attenuation hardly occurs. That is, since the state changes depending on the lift amount of the needle 30 and the state where the needle 30 is not restricted, the magnitude of the attenuation also changes depending on the lift amount, so that the detection accuracy of the injection state is lowered.

  On the other hand, according to the present embodiment, the sensor element 80 is arranged so as to detect the fuel pressure in the fuel reservoir 24 (passage between the sheet guides) located on the upstream side of the seat surface 331, so that the fuel pressure change according to the lift amount It is possible to detect the fuel pressure at the place where is suppressed. Therefore, the detection accuracy of the injection state can be improved.

  (2) If the sensor element 80 is disposed so as to detect the fuel pressure in the communication path R2 (passage between guides) contrary to the present embodiment, the following problems arise. That is, the passage cross-sectional area of the communication passage R2 is reduced in the communication passage R2 because the passage cross-sectional area is small. Then, since the pressure fluctuation generated in the nozzle hole 22 is attenuated in the communication path R2, the pressure fluctuation in the communication path R2 differs from the pressure fluctuation in the nozzle hole 22 actually generated. This reduces the detection accuracy of the injection state.

  On the other hand, according to the present embodiment, the sensor element 80 is disposed so as to detect the fuel pressure in the fuel reservoir chamber 24 (passage between the sheet guides) located on the downstream side of the communication passage R2, so that the pressure fluctuation in the nozzle hole 22 is detected. It is possible to detect pressure fluctuations close to the above state. Therefore, the detection accuracy of the injection state can be improved.

  (3) If the sensor element 80 is arranged so as to detect the fuel pressure of the high pressure passages 42, 51, 23 located upstream of the communication passage R2 contrary to the present embodiment, it is generated in the nozzle hole 22. The time required for the fuel pressure fluctuation to propagate to the high-pressure passages 42, 51, 23 becomes a propagation delay (time lag), and the detection accuracy of the injection state decreases. On the other hand, according to the present embodiment, since the fuel pressure in the fuel reservoir chamber 24 (passage between the sheet guides) located on the downstream side of the communication passage R2 is detected, the time lag can be reduced and the detection accuracy of the injection state can be improved. .

  (4) Further, according to the present embodiment, the sensor element 80 is disposed outside the fuel reservoir chamber 24 (passage between the sheet guides) (the outer wall surface 20a of the nozzle body 20), so that the lead wire 81 (wiring) that outputs a detection signal is provided. ) Can be disposed along the outer peripheral surfaces of the nozzle body 20 and the holder body 40, and the wiring path can be easily secured.

(Second Embodiment)
In the first embodiment, the sensor element 80 is attached to the outer wall surface 20 a of the nozzle body 20, whereas in the present embodiment shown in FIG. 5, a fuel reservoir is provided in the needle cylindrical portion 31 from the opposite side of the fuel reservoir chamber 24. An insertion hole 35 extending in the axial direction to the vicinity of the chamber 24 is formed. The axial center of the insertion hole 35 coincides with the axial center of the needle 30. The sensor element 80 is attached to the inner peripheral surface 35 b of the insertion hole 35, which is a portion of the needle cylindrical portion 31 that forms the fuel reservoir chamber 24 (hereinafter referred to as “side wall portion 35 a”).

  In the present embodiment, a strain gauge is employed as the sensor element 80. This strain gauge is fixed by being sealed (baked) with a glass member (not shown) in a state of being disposed on the inner peripheral surface 35b of the insertion hole 35. Therefore, the sensor element 80 detects the magnitude of the strain (elastic deformation amount) of the side wall portion 35a of the needle 30 generated according to the fuel pressure in the fuel reservoir chamber 24, whereby the fuel pressure in the fuel reservoir chamber 24 is detected. It will be.

  A lead wire 81 that electrically connects various circuits such as an amplifier circuit (not shown) and the sensor element 80 is disposed inside the insertion hole 35 and is connected to the connector from the side wall 35a through the insertion hole (not shown) formed in the holder body 40. It is routed to the housing 70.

  According to the present embodiment having the above configuration, the same effect as that of the first embodiment is exhibited. Further, in the first embodiment, it is necessary to arrange the lead wire 81 outside the nozzle body 20, but according to the present embodiment, the lead wire 81 is arranged inside the nozzle body 20, so that the lead wire 81 is It is possible to reliably avoid contact with the external member.

(Third embodiment)
In the first embodiment, the sensor element 80 is attached to the outer wall surface 20a of the nozzle body 20 (reservoir chamber portion 20b), whereas in the present embodiment shown in FIG. The sensor element 800 is attached to the wall surface 20c. Therefore, the sensor element 800 is disposed so as to be exposed to the fuel reservoir 24.

  In the present embodiment, a piezoelectric element (pressure detection element) is employed as the sensor element 800, and the sensor element 800 outputs a change in electromotive force generated in the piezoelectric element according to the fuel pressure in the fuel reservoir 24 as a detection signal. . As a result, the fuel pressure in the fuel reservoir 24 is detected.

  According to the present embodiment having the above configuration, the same effect as that of the first embodiment is exhibited. In the first embodiment, the strain gauge 80 indirectly detects the fuel pressure based on the elastic deformation amount of the reservoir chamber 20b generated according to the fuel pressure of the fuel reservoir 24. Since the element 800 directly detects the fuel pressure, the detection accuracy of the fuel pressure can be improved.

(Fourth embodiment)
In the third embodiment, the sensor element 800 is attached to the inner wall surface 20 c of the nozzle body 20, whereas in the present embodiment shown in FIG. 7, an outer peripheral surface (side surface portion) that forms the fuel reservoir chamber 24 in the needle 30. The sensor element 800 is attached to 30c). Therefore, the sensor element 800 is disposed so as to be exposed to the fuel reservoir 24.

  In the present embodiment, a piezoelectric element (pressure detection element) is employed as the sensor element 800, and the sensor element 800 outputs a change in electromotive force generated in the piezoelectric element according to the fuel pressure in the fuel reservoir 24 as a detection signal. . As a result, the fuel pressure in the fuel reservoir 24 is detected.

  According to the present embodiment having the above configuration, the same effects as those of the third embodiment are exhibited.

(Fifth embodiment)
When the sensor element 800 (fuel pressure sensor) is arranged in the fuel reservoir 24 (passage R1 between the sheet guides) as in the third and fourth embodiments, the sensor element 80 as in the first and second embodiments. If the detection signal is to be transmitted by wire through the lead wire 81, for example, it is necessary to provide a through hole in the reservoir portion 20b or the needle 30, and to take out the lead wire 81 from the sheet guide passage R1 through the through hole. This is not a realistic configuration, such as requiring a complicated seal structure in the through hole.

  Therefore, in the present embodiment, a transmission circuit (transmission means) that wirelessly outputs and transmits the detection signal of the sensor element 800 is disposed in the sheet guide passage R1 together with the sensor element 800. Then, a receiving circuit (receiving means) that receives the detection signal wirelessly transmitted from the transmitting circuit is disposed outside the sheet guide passage R1.

  As shown in FIG. 8, the transmission circuit 82 is configured to include electronic components such as a primary coil 82a, and is attached to the inner wall surface 20c of the reservoir chamber 20b or the side surface 30c of the needle 30 while being molded with a resin material. It has been. The transmission circuit 82 is electrically connected to the piezoelectric element 800. When the piezoelectric element 800 receives the pressure of the fuel and generates a current I1, the current I1 flows through the primary coil 82a to generate an electromagnetic wave. That is, an electromagnetic wave having a magnitude corresponding to the fuel pressure is wirelessly transmitted as a detection signal.

  The receiving circuit 90 that receives the detection signal transmitted from the transmitting circuit 82 is configured by molding electronic components such as the secondary coil 90a and the amplifier 90b with a resin material, and is disposed inside the electromagnetic unit 60, for example. Due to the output of an electromagnetic wave (detection signal) from the primary coil 82a of the transmission circuit 82, a secondary current I2 is generated in the secondary coil 90a of the reception circuit 90. The secondary current I2 is amplified by the amplifier 90b and output from the sensor terminal 71 (see FIG. 1) via a lead wire (not shown) connected to the output terminal 90c. Thereby, the detection signal of the piezoelectric element 800 is transmitted and received wirelessly.

  As described above, according to the present embodiment, since the detection signal of the sensor element 800 is transmitted and received wirelessly, the through hole and the seal structure (wiring route) required when the detection signal is wired by the lead wire 81 are secured. Therefore, it is possible to easily arrange the sensor element 800 in the sheet guide passage R1.

(Sixth embodiment)
In the transmission circuit 82 and the reception circuit 90 according to the fifth embodiment, the detection signal is wirelessly transmitted by electromagnetic waves, whereas in the present embodiment shown in FIG. 9, the detection signal is wirelessly transmitted by electromagnetic induction. .

  Specifically, as shown in FIG. 9, the transmission circuit 83 is electrically connected to the piezoelectric element 800, and when the piezoelectric element 800 receives the pressure of fuel and generates a current I1, the current I1 flows through the primary coil 83a. Thus, an induced current I2 is generated in the secondary coil 91a of the receiving circuit 91. That is, an electromagnetic wave having a magnitude corresponding to the fuel pressure is wirelessly transmitted as a detection signal.

  The induced current I2 generated in the secondary coil 91a of the receiving circuit 91 is amplified by the amplifier 91b, and from the sensor terminal 71 (see FIG. 1) via a lead wire (not shown) connected to the output terminal 91c. Is output. Thereby, the detection signal of the piezoelectric element 800 is transmitted and received wirelessly. As described above, the same effects as those of the fifth embodiment are also exhibited by this embodiment.

(Other embodiments)
The present invention is not limited to the description of the above embodiment, and may be modified as follows. Moreover, you may make it combine the characteristic structure of each embodiment arbitrarily, respectively.

  In each of the above embodiments, the sensor elements 80 and 800 are arranged so as to detect the fuel pressure in the fuel reservoir chamber 24 located at the uppermost stream of the first fuel passage R1, but the fuel reservoir chamber in the first fuel passage R1. The sensor elements 80 and 800 may be arranged so as to detect the fuel pressure in the downstream portion of 24.

  For example, in the first embodiment, the sensor element 80 may be attached to a portion of the outer wall surface 20a of the nozzle body 20 that is located below the fuel reservoir chamber 24 and above the second fuel passage S. Further, in the second embodiment, the insertion hole 35 is formed so as to extend downward from the fuel reservoir chamber 24, the inner peripheral surface 35 b of the insertion hole 35 is below the fuel reservoir chamber 24, and the second fuel The sensor element 80 may be attached to a portion located above the passage S.

  In the third embodiment, the sensor element 800 may be attached to a portion of the inner wall surface 20c of the nozzle body 20 that is located below the fuel reservoir chamber 24 and above the second fuel passage S. In the fourth embodiment, the sensor element 800 may be attached to a portion of the side surface portion 30c of the needle 30 that is positioned below the fuel reservoir chamber 24 and above the second fuel passage S.

  In the first embodiment, the electromagnetic unit 60 composed of a stator and an armature is used as an electric actuator that opens and closes the needle 30. However, a laminated body (piezo stack) formed by laminating a large number of piezoelectric elements. A configured piezo actuator may be employed.

  In each of the above embodiments, the present invention is applied to a so-called pencil-type fuel injection valve in which a pipe joint 41 is provided at the upper end portion of the holder body 40 and high pressure fuel is supplied from the side opposite to the injection hole of the holder body 40. However, a pipe joint may be provided on the outer peripheral portion of the holder body 40 and applied to a fuel injection valve configured to supply high-pressure fuel from the outer peripheral surface side of the holder body 40.

  In each of the above embodiments, the present invention is applied to an injector of a diesel engine. However, the present invention may be applied to a gasoline engine, particularly, a direct injection gasoline engine that directly injects fuel into a combustion chamber.

  DESCRIPTION OF SYMBOLS 10 ... Fuel injection valve, 20 ... Nozzle body (body), 20a ... Body outer wall surface, 20c ... Body inner wall surface, 22 ... Injection hole, 24 ... Fuel reservoir chamber (passage between sheet guides), 30 ... Needle, 30b ... Guide part, 30c ... Side face part of needle, 35 ... Insertion hole, 80 ... Strain gauge (strain detection element (sensor element)), 221 ... Seating surface, 331 ... Seat surface, 800 ... Piezoelectric element (pressure detection element (sensor element) )), R1... First fuel passage (passage between seat guides), R2... Communication passage (passage between guides),.

Claims (9)

A body in which a nozzle hole for injecting fuel is formed at the tip, and a needle housed in the body;
The fuel injection from the nozzle hole is blocked by seating the seat surface formed on the needle on the seating surface formed inside the body, and the nozzle hole is separated from the seating surface by separating the seat surface from the seating surface. In a fuel injection valve for injecting fuel from
On the outer peripheral surface of the needle, a plurality of guide portions that slide with the inner peripheral surface of the body and restrict the movement of the needle in the radial direction are formed side by side in the circumferential direction of the outer peripheral surface,
An inter-guide passage for supplying fuel to the nozzle hole is formed between the plurality of guide portions,
A passage between seat guides for supplying fuel to the nozzle holes between a portion of the outer peripheral surface of the needle upstream of the seat surface and downstream of the guide portion and the inner peripheral surface of the body Formed,
A fuel injection valve comprising a fuel pressure sensor arranged to detect a fuel pressure in the passage between the seat guides.   2. The fuel injection valve according to claim 1, wherein the fuel pressure sensor is arranged on a side surface portion of the needle located in the passage between the seat guides.   2. The fuel injection valve according to claim 1, wherein the fuel pressure sensor is disposed on an inner wall surface of a portion of the body that forms the passage between the sheet guides. 3.   4. The fuel injection valve according to claim 2, wherein the fuel pressure sensor includes a pressure detection element arranged to be exposed in the passage between the seat guides. 5. An insertion hole extending in the axial direction of the needle is formed in the needle,
2. The fuel injection valve according to claim 1, wherein the fuel pressure sensor is arranged in a portion of the insertion hole located in the passage between the seat guides.   The fuel injection valve according to claim 5, wherein the fuel pressure sensor includes a strain detection element that detects an elastic deformation amount generated in a side wall portion of the insertion hole.   2. The fuel injection valve according to claim 1, wherein the fuel pressure sensor is arranged on an outer wall surface of a portion of the body located in the passage between the seat guides.   The fuel according to claim 7, wherein the fuel pressure sensor includes a strain detection element that detects an elastic deformation amount generated in a portion of the body that forms the passage between the sheet guides. Injection valve.   The fuel injection valve according to any one of claims 1 to 8, wherein the fuel pressure sensor includes transmission means for outputting and transmitting a detection signal wirelessly.

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