JP2011047280A - Fuel injection valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection valve for making both compatible in reducing pulsation superimposed on a detection value of a fuel pressure sensor and securing strength of a body. <P>SOLUTION: This fuel injection valve is mounted on an internal combustion engine, and injects fuel from a nozzle port, and includes the body 4 forming high pressure passages 601 and 602 inside for making high pressure fuel flow to the nozzle port and the fuel pressure sensor installed in the body 4 and detecting pressure of the high pressure fuel, and is characterized in that the body 4 is formed with branch passages 81 and 82 branching off from the high pressure passage 602 and introducing the high pressure fuel to the fuel pressure sensor, and a passage diameter D1 of a branch part 6a communicating the high pressure passage 602 among the branch passages 81 and 82, is formed smaller than a passage diameter D2 of a downstream part 6b positioned on the fuel pressure sensor side more than the branch part 6a of the branch passage 8. <P>COPYRIGHT: (C)2011,JPO&amp;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.

  Conventionally, this type of fuel injection valve houses a needle valve that opens and closes a nozzle hole, an electric actuator that opens and closes the needle valve, and the like in a body formed with a high-pressure passage through which high-pressure fuel flows to the nozzle hole. Generally, it is configured.

  In recent years, a structure in which a fuel pressure sensor is attached to a body has been proposed in order to detect the pressure of high-pressure fuel as close to the injection hole as possible (see Patent Documents 1 to 3). According to this, since the change in the fuel pressure at the nozzle hole can be detected more accurately than, for example, the fuel pressure sensor attached to the common rail, 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 maximum injection rate can be detected by detecting the magnitude of the descent.

JP 2009-114972 A JP 2009-114971 A JP 2009-114970 A

  Patent Documents 1 to 3 describe a configuration in which a high-pressure passage that allows high-pressure fuel to flow to the nozzle hole and a branch passage that branches from the high-pressure passage and guides the high-pressure fuel to the fuel pressure sensor are formed inside the body. . As for the fuel injection valve having such a configuration, the inventors of the present invention examined the two types of fuel injection valves a1 and a2 shown in FIG. 3A, and obtained the following knowledge.

  In other words, the portion 4a of the body 4 where the high pressure passage 6 and the branch passage 8 intersect is required to have sufficient strength so as not to be damaged by the pressure of the high pressure fuel, but as the passage diameter of the branch passage 8 is reduced. The strength of the intersecting portion 4a with respect to the fuel pressure can be increased. The fuel injection valve a1 attempts to keep the generated stress within the allowable stress range by reducing the diameter of the branch passage 8 (see b1 in FIG. 3B).

  Here, when the needle valve is opened and closed to inject fuel from the nozzle hole, the detection value of the fuel pressure sensor 50 varies as follows. That is, the detected value starts decreasing with the start of fuel injection, and then the detected value increases as the injection rate decreases. However, the actual detection value varies as described above while pulsating at a high frequency. FIG. 3C is a graph showing a theoretical value obtained by extracting only the pulsation component from the fluctuating detection value, and it has been found that the amplitude of the pulsation increases as the branch passage becomes smaller in diameter. And if pulsation becomes large in this way, it will become difficult to acquire the fluctuation | variation of the detected value which arises with injection with high precision.

  That is, there is a trade-off between securing the strength of the intersecting portion 4a and reducing pulsation. According to the fuel injection valve a1 having the small diameter of the branch passage 8, the generated stress can be within the allowable stress range, but the pulsation increases. (See c1 in FIG. 3C). On the other hand, according to the fuel injection valve a2 in which the branch passage 8 has a large diameter, the pulsation can be reduced (see c2 in FIG. 3C), but the generated stress exceeds the allowable stress (FIG. 3B). The occurrence of cracks as indicated by the symbol P in FIG. 3A is concerned.

  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 that realizes both reduction of pulsation superimposed on a detection value of a fuel pressure sensor and securing of body strength. There is to do.

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

  According to a first aspect of the present invention, in a fuel injection valve mounted on an internal combustion engine for injecting fuel from an injection hole, a body that forms a high-pressure passage for allowing high-pressure fuel to flow through the injection hole is attached to the body. A fuel pressure sensor that detects the pressure of the high-pressure fuel, and the body is formed with a branch passage that branches from the high-pressure passage and guides the high-pressure fuel to the fuel pressure sensor. The passage diameter of the branch portion communicating with the passage is smaller than the passage diameter of the downstream portion of the branch passage located on the fuel pressure sensor side with respect to the branch portion.

  In short, in the above invention, the passage diameter of the branch portion communicating with the high-pressure passage among the branch passages and the passage diameter of the downstream portion located on the fuel pressure sensor side of the branch passage are formed in different sizes. Yes. And since the passage diameter of a branch part is made smaller than the passage diameter of a downstream part, the intensity | strength of the part which a high voltage | pressure passage and a branch passage cross | intersect among bodies can fully be ensured. Moreover, since the passage diameter of the downstream part is made larger than the passage diameter of the branch part, the amplitude of the pulsation superimposed on the fuel pressure sensor can be reduced. As described above, according to the present invention, it is possible to achieve both reduction of pulsation superimposed on the detection value of the fuel pressure sensor and securing of the strength of the body.

  According to a second aspect of the present invention, the branch passage has an upstream passage in which a predetermined passage length including the branch portion is formed with a constant passage diameter, and a predetermined passage length including the downstream portion is formed in a constant passage diameter. A downstream passage, wherein the passage diameter of the downstream passage is smaller than the passage diameter of the upstream passage.

  Accordingly, when the body is drilled to form the branch passage, the upstream passage and the downstream passage can be separately drilled using two types of drills having different diameters. Therefore, it is possible to easily form the branch passage so as to have portions having different passage diameters (a branch portion and a downstream portion) using a highly versatile drill.

  According to a third aspect of the present invention, the branch passage includes a tapered passage communicating with the downstream passage and the upstream passage, and the tapered passage extends from the communication point with the downstream passage to the upstream passage. It is characterized in that it is formed in a taper shape so that the passage diameter gradually decreases over the communication points.

  According to this, pressure loss generated in the branch passage can be reduced as compared with the case where the tapered passage is eliminated and the downstream passage and the upstream passage are directly communicated with each other. Therefore, it is possible to acquire the fluctuation of the detected value of the fuel pressure sensor caused by the injection with high accuracy.

  According to a fourth aspect of the present invention, the branch passage includes a downstream passage in which a predetermined passage length including the downstream portion is formed with a constant passage diameter, and a tapered passage communicating with the downstream passage and the branch portion. The tapered passage is formed in a tapered shape so that the diameter of the passage gradually decreases from a communication location with the downstream passage to a communication location with the branch site.

  According to this, since the taper passage can be formed with the cutting edge of the drill used at the same time when the downstream passage is drilled, both the downstream passage and the taper passage can be formed simultaneously by one drilling. . Therefore, the workability can be improved when the branch passage is drilled.

  The invention according to claim 5 is characterized in that the branch passage is formed in a taper shape so that the passage diameter gradually decreases from a communication location with the fuel pressure sensor to a communication location with the high-pressure passage.

  According to this, since the whole branch passage is formed in a taper shape, pressure loss generated in the branch passage can be reduced as compared with a case where a passage having a predetermined passage length and a constant passage diameter is provided. Therefore, it is possible to acquire the fluctuation of the detected value of the fuel pressure sensor caused by the injection with high accuracy.

  The invention according to claim 6 is characterized in that a passage diameter of the branch portion is set to be equal to or smaller than a passage diameter of the high-pressure passage.

  Here, if the strength of the portion of the body where the high pressure passage and the branch passage intersect is kept constant, the passage diameter of the high pressure passage is increased and the passage diameter of the high pressure passage is reduced as the passage diameter of the branch portion is reduced. As a result, the present inventors have made it clear that the diameter of the branch portion should be increased. Since the high-pressure passage allows fuel to flow to the nozzle hole, the passage diameter of the high-pressure passage is increased in preference to increasing the passage diameter of the branching portion and reducing the pressure loss generated in the branch passage. Therefore, it is desirable to reduce the pressure loss generated in the high-pressure passage.

  According to the above invention in view of this point, the passage diameter of the branch portion is made equal to or smaller than the passage diameter of the high-pressure passage. Therefore, the passage diameter of the high-pressure passage can be sufficiently increased to reduce the pressure loss generated in the high-pressure passage. it can.

  The invention according to claim 7 is characterized in that the branch passage is branched from a portion extending linearly in the high-pressure passage, and the passage diameter of the branch portion is made smaller than the passage diameter of the high-pressure passage. To do.

  According to this, after drilling the high-pressure passage, the drilling position of the branch passage is slightly shifted in the radial direction when the branch passage is formed by drilling toward the linearly extending portion of the high-pressure passage. However, since the passage diameter of the branch portion of the branch passage is set smaller than the passage diameter of the high-pressure passage, the possibility that the branch portion protrudes from the high-pressure passage can be reduced. That is, machining position variations when drilling the branch passage can be absorbed, and the workability of the branch passage and the high-pressure passage can be improved.

  In the invention according to claim 8, the intersection angle between the passage length direction of the portion including the branch portion of the branch passage and the passage length direction of the portion communicating with the branch portion of the high-pressure passage is approximately 90 degrees. It is characterized by that.

  Contrary to the above-mentioned invention, when the crossing angle is made oblique, a part of the body surrounding the branching portion projects into an acute angle. As a result, the sharp-angled portion easily breaks against the fuel pressure, which is disadvantageous in ensuring the strength of the body against the fuel pressure. On the other hand, according to the above invention, since the crossing angle is set to approximately 90 degrees, the above-described acute angle shape portion can be eliminated, and it is advantageous to ensure the strength of the body against the fuel pressure.

1 is a schematic cross-sectional view showing a schematic internal configuration of a fuel injection valve according to a first embodiment of the present invention. Sectional drawing which shows the single-piece | unit structure of the body shown in FIG. It is a figure explaining the effect of this invention, Comprising: The left side column and the middle column in a figure show the fuel injection valve made as a prototype for comparison with this invention, The right side column in a figure shows the fuel which concerns on 1st Embodiment. Indicates an injection valve. Sectional drawing which shows the fuel injection valve which concerns on 2nd Embodiment of this invention. The side view of the drill blade used for drilling the branch passage which concerns on 2nd Embodiment. Sectional drawing which shows the fuel injection valve which concerns on 3rd Embodiment of this invention. Sectional drawing which shows the fuel injection valve which concerns on 4th Embodiment of this invention. Sectional drawing which shows the fuel injection valve which concerns on 5th Embodiment of this invention. Sectional drawing which shows the fuel injection valve which concerns on 6th Embodiment of this invention.

  Hereinafter, embodiments embodying the present invention will be described 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. Further, the present invention is not limited to the description of the embodiments described below, and the characteristic configurations of the embodiments may be arbitrarily combined.

(First embodiment)
A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a schematic cross-sectional view showing a schematic internal configuration of a fuel injection valve a3 (injector) according to the present embodiment. First, based on FIG. 1, the basic configuration and operation of the fuel injection valve a3 will be described. To do.

  The fuel injection valve a3 is a nozzle that injects high-pressure fuel stored in a common rail (pressure accumulator) (not shown) into a combustion chamber E1 formed in a cylinder of a diesel internal combustion engine, and injects fuel when the valve is opened. 1. An electric actuator 2 that is driven by power supply and a back pressure control mechanism 3 that is driven by the electric actuator 2 and controls the back pressure of the nozzle 1 are provided.

  The nozzle 1 includes a nozzle body 12 in which an injection hole 11 is formed, a needle valve 13 that opens and closes the injection hole 11 by making contact with and separating from the valve seat of the nozzle body 12, and a spring 14 that urges the needle valve 13 in a valve closing direction. .

  The electric actuator 2 employs a piezo actuator composed of a laminated body (piezo stack) formed by laminating a large number of piezo elements. By switching between charging and discharging of the piezo elements, an extension state and a contraction state are achieved. Is switched. Accordingly, the piezo stack functions as an actuator that operates the needle valve 13. In place of the piezo actuator, an electromagnetic actuator constituted by a stator and an armature may be employed.

  The valve body 31 of the back pressure control mechanism 3 is driven by a piston 32 that moves following the expansion and contraction of the piezoelectric actuator 2, a disc spring 33 that biases the piston 32 toward the piezoelectric actuator 2, and a piston 32. A spherical valve element 34 is accommodated.

  The substantially cylindrical fuel injection valve body 4 has a stepped columnar storage hole 41 extending in the axial direction of the fuel injection valve (vertical direction in FIG. 1) at the center in the radial direction. The piezo actuator 2 and the back pressure control mechanism 3 are accommodated. Further, the nozzle 1 is held at the end of the fuel injection valve body 4 by screwing the substantially cylindrical retainer 5 into the fuel injection valve body 4.

  The nozzle body 12, the fuel injection valve body 4, and the valve body 31 are formed with a high pressure passage 6 to which high pressure fuel is always supplied from the common rail, and a low pressure passage 7 connected to a fuel tank (not shown). Further, these bodies 12, 4 and 31 are made of metal, and have been increased in strength by performing a quenching process, and the surface has been increased in hardness by performing a carburizing process.

  These bodies 12, 4 and 31 are inserted and arranged in a body insertion hole E3 formed in a cylinder head E2 of the internal combustion engine. The fuel injection valve body 4 is formed with an engaging portion 42 (pressing surface) that engages with one end of the clamp K. By tightening the other end of the clamp K to the cylinder head E2 with a bolt, one end of the clamp K is The engaging portion 42 is pressed toward the body insertion hole E3. Thereby, the fuel injection valve a3 is fixed in a state of being pressed into the body insertion hole E3.

  A high pressure chamber 15 that is a part of the high pressure passage 6 is formed between the outer peripheral surface of the needle valve 13 on the nozzle hole 11 side and the inner peripheral surface of the nozzle body 12. The high pressure chamber 15 communicates with the nozzle hole 11 when the needle valve 13 is displaced in the valve opening direction. A back pressure chamber 16 is formed on the side opposite to the injection hole in the needle valve 13 (hereinafter referred to as “upper side”). In the back pressure chamber 16, the above-described spring 14 is disposed.

  The valve body 31 is formed with a high-pressure seat surface 35 in a path communicating the high-pressure passage 6 in the valve body 31 and the back pressure chamber 16 of the nozzle 1, and the back of the low-pressure passage 7 in the valve body 31 and the nozzle 1. A low-pressure seat surface 36 is formed in a path communicating with the pressure chamber 16. The valve body 34 described above is disposed between the high pressure seat surface 35 and the low pressure seat surface 36.

  A high pressure port 43 connected to a high pressure pipe (not shown) and a low pressure port 44 connected to a low pressure pipe (not shown) are formed on the outer peripheral surface of the fuel injection valve body 4 having a substantially cylindrical shape. The fuel supplied from the common rail to the high-pressure port 43 through the high-pressure pipe is supplied from the outer peripheral surface side of the cylindrical fuel injection valve body 4. The fuel supplied to the fuel injection valve a <b> 3 flows into the high pressure chamber 15 and the back pressure chamber 16 through the high pressure passage 6. The high-pressure passage 6 is formed with a branch passage 8 that branches to the upper side of the fuel injection valve body 4. By this branch passage 8, the fuel in the high pressure passage 6 is introduced into a fuel pressure sensor 50 described later.

  A connector 60 is attached to the upper part of the fuel injection valve body 4. The electric power supplied from the outside to the drive connector terminal 62 among the terminals of the connector 60 is supplied to the piezo actuator 2 via the lead wire 21, whereby the piezo actuator 2 expands and contracts when the power supply is stopped. The lead wire 21 is inserted and arranged in a lead wire insertion hole 47a formed in the body 4 while being held by the holding member 21a.

  In the above configuration, when the piezo actuator 2 is contracted, the valve body 34 is in contact with the low pressure seat surface 36 and the back pressure chamber 16 is connected to the high pressure passage 6 as shown in FIG. Fuel pressure is introduced. The needle valve 13 is urged in the valve closing direction by the fuel pressure in the back pressure chamber 16 and the spring 14 to close the nozzle hole 11.

  On the other hand, when a voltage is applied to the piezo actuator 2 and the piezo actuator 2 is extended, the valve body 34 is in contact with the high pressure seat surface 35, the back pressure chamber 16 is connected to the low pressure passage 7, and the back pressure chamber 16 has a low pressure. become. The needle valve 13 is urged in the opening direction by the fuel pressure in the high pressure chamber 15 to open the injection hole 11, and fuel is injected from the injection hole 11 into the combustion chamber E 1.

  Here, the pressure of the high-pressure fuel in the high-pressure passage 6 varies with fuel injection from the nozzle hole 11. A fuel pressure sensor 50 that detects this pressure fluctuation is attached to the fuel injection valve body 4. In the pressure fluctuation waveform detected by the fuel pressure sensor 50, the actual injection start timing can be detected by detecting the timing when the fuel pressure starts to decrease with the start of injection from the nozzle hole 11. Moreover, the actual injection end time can be detected by detecting the time when the fuel pressure starts to increase with the end of injection. Further, in addition to the injection start timing and the injection end timing, the actual maximum injection rate can be detected by detecting the maximum value of the fuel pressure decrease amount caused by the injection.

  The fuel pressure sensor 50 is made of a metal stem 51 (a strain generating body) that is elastically deformed by the pressure of the high-pressure fuel in the branch passage 8, and the magnitude of strain generated in the stem 51 is converted into an electric signal to generate a pressure. And a strain gauge (sensor element) 52 that outputs the detected value.

  The stem 51 includes a cylindrical cylindrical portion 51b having an inlet 51a formed at one end for introducing high-pressure fuel therein, and a disc-shaped diaphragm portion 51c that closes the other end of the cylindrical portion 51b. ing. The pressure of the high-pressure fuel that has flowed into the cylindrical portion 51b from the inlet 51a is received by the inner surface of the cylindrical portion 51b and the diaphragm portion 51c, whereby the entire stem 51 is elastically deformed.

  A concave portion 45 into which the cylindrical portion 51b of the stem 51 is inserted is formed on the upper end surface of the fuel injection valve body 4 formed in a substantially columnar shape. A female screw portion 45a is formed on the inner peripheral surface of the recess 45, and a male screw portion 51d is formed on the outer peripheral surface of the cylindrical portion 51b. The fuel pressure sensor 50 is attached to the fuel injection valve body 4 by screwing the male screw portion 51 d of the stem 51 to the female screw portion 45 a of the fuel injection valve body 4. The recess 45 is formed so that the cylindrical axis center of the stem 51 coincides with the axis center of the body 4.

  By the way, in a state where the body 4 is pressed into the body insertion hole E3 by the clamp K, a portion of the body 4 from the engaging portion 42 to the injection hole 11 is distorted by the pressing force. In this embodiment in view of this point, the stem 51 is disposed on the opposite side of the injection hole 11 with respect to the engaging portion 42. Thereby, the stem 51 can be prevented from being distorted by the pressing force, and the detection accuracy of the fuel pressure can be improved.

  A sensor-side seal surface 51e is formed on the cylindrical end surface of the cylindrical portion 51b located around the inflow port 51a, and a body-side seal surface 45b is formed on the bottom surface of the recess 45. Both the sealing surfaces 51e and 45b are surfaces extending in a direction perpendicular to the axial direction of the stem 51 (the vertical direction in FIG. 1), and have a shape extending in an annular shape around the inflow port 51a.

  The sensor-side seal surface 51e is pressed against the body-side seal surface 45b so that the sensor-side seal surface 51e is brought into intimate contact with the fuel-injection valve body 4 and the stem 51 to form a metal touch seal. The force (axial force) that presses both the seal surfaces 51e and 45b is generated by screwing the stem 51 to the fuel injection valve body 4. That is, the attachment of the stem 51 to the fuel injection valve body 4 and the generation of the axial force are performed simultaneously.

  The strain gauge 52 is attached to the diaphragm portion 51c. More specifically, the strain gauge 52 is fixed by being sealed (baked) by the glass member 52b while being disposed on the diaphragm portion 51c. Therefore, when the stem 51 is elastically deformed so as to expand due to the pressure of the high-pressure fuel flowing into the cylindrical portion 51b, the strain gauge 52 detects the magnitude of the strain (elastic deformation amount) generated in the diaphragm portion 51c. .

  The mold IC 54 held by the stem 51 is electrically connected to the strain gauge 52 by wire bonding, and is configured by sealing the electronic component 54a and the sensor terminal 54b with a mold resin. The electronic component 54a constitutes an amplifier circuit that amplifies the detection signal output from the strain gauge 52, a filtering circuit that removes noise superimposed on the detection signal, a circuit that applies a voltage to the strain gauge 52, and the like.

  Note that the strain gauge 52 to which a voltage is applied from the voltage application circuit constitutes a bridge circuit whose resistance value changes in accordance with the magnitude of the strain generated in the diaphragm portion 51c. As a result, the output voltage of the bridge circuit changes according to the distortion of the diaphragm portion 51c, and the output voltage is output to the amplification circuit of the mold IC 54 as the pressure detection value of the high-pressure fuel. The amplifier circuit amplifies the pressure detection value output from the strain gauge 52 (bridge circuit), and outputs the amplified signal from the sensor terminal 54b.

  The sensor terminal 54b is electrically connected to the electronic component 54a inside the mold IC 54, and functions as a terminal for outputting a detection signal of the fuel pressure sensor, a terminal for supplying power, a grounding terminal, and the like. The housing 61 of the connector 60 described above holds the sensor connector terminal 63 together with the drive connector terminal 62. The sensor connector terminal 63 and the sensor terminal 54b are electrically connected via the electrode 71 by laser welding or the like. The connector 60 is connected to a connector of an external harness that is connected to an external device such as an engine ECU (not shown). Thereby, the pressure detection signal output from mold IC54 is input into engine ECU via an external harness.

  Next, the branch passage 8 which is a main part of the present embodiment will be described in detail with reference to FIG. FIG. 2 is a cross-sectional view showing the body 4 alone and the fuel pressure sensor 50, and hatching indicating the cross section is omitted.

  The high pressure passage 6 includes a passage portion 601 extending linearly in the fuel injection valve axial direction (vertical direction in FIG. 1), and a passage portion 602 extending linearly from the upper end of the passage portion 601 to the inlet of the high pressure port 43. It is prepared for. The branch passage 8 is branched from a portion of the passage portion 602 between the inlet of the high pressure port 43 and the upper end of the passage portion 601.

  The branch passage 8 includes an upstream passage 81 in which a predetermined passage length L1 is formed with a constant passage diameter D1, and a downstream passage 82 in which a predetermined passage length L2 is formed with a constant passage diameter D2. Yes. A portion of the upstream passage 81 that communicates with the high-pressure passage 6 (passage portion 602) in the upstream end portion of the upstream passage 81 corresponds to the branch portion 6a. Further, a portion from the upstream end portion to the downstream end portion of the downstream passage 82 and a portion from a portion communicating with the upstream passage 81 to a portion communicating with the recess 45 in the downstream passage 82 is a downstream portion. This corresponds to 6b. The downstream end of the downstream passage 82 is located at the center of the bottom surface of the recess 45, and the body-side seal surface 45b is formed around the downstream passage 82 in the bottom surface.

  Since the passage portions 601, 602, the upstream passage 81, and the downstream passage 82 are formed by drilling, the passage cross-sectional shape is circular. The passage diameter D 1 of the upstream side passage 81 is smaller than the passage diameter D 2 of the downstream side passage 82 and smaller than the passage diameter D 3 of the passage portion 602. A filter insertion portion 602a for inserting and arranging a filter (not shown) is formed in the passage portion 602 upstream of the branch portion 6a. The passage diameter D4 of the filter insertion portion 602a is larger than the passage diameter D3 of the branch portion 6a in the passage portion 602.

  The upstream-side passage 81 and the downstream-side passage 82 are linearly extended from the branch portion 6 a to the downstream portion 6 b, and the central axis θ1 of the upstream-side passage 81 and the central axis θ1 of the downstream-side passage 82 coincide with each other. Further, the intersection angle α between the central axis θ1 of the upstream passage 81 and the central axis θ2 of the passage portion 602 is 90 degrees. The direction of the central axis θ1 corresponds to the passage length direction of the portion including the branch portion 6a, and the central axis θ2 corresponds to the passage length direction of the portion of the high-pressure passage 6 communicating with the branch portion 6a. Thus, since the crossing angle α is 90 degrees, it is possible to avoid a part of the body 4 surrounding the branch portion 6a (the protruding portion indicated by reference numeral 4a) from protruding into an acute angle. The protrusion tip angle β of the portion 4a is 90 degrees.

  The passage length L2 of the downstream passage 82 is longer than the passage length L1 of the upstream passage 81. The passage length L <b> 2 of the downstream passage 82 is longer than the passage diameter D <b> 2 of the downstream passage 82. The branch portion 6 a is located on the nozzle hole 11 side of the body 4 with respect to the engaging portion 42.

  Next, a procedure for forming the passage portions 601, 602, the upstream passage 81, and the downstream passage 82 by drilling the body 4 will be described.

  First, the passage portion 602 is formed by drilling from the high-pressure port 43. Thereafter, the passage portion 601 is formed so as to communicate with the passage portion 602 by drilling from the nozzle hole side end face of the body 4 toward the passage portion 602. Note that a drill having a smaller diameter than the drill forming the passage portion 602 is used as the drill forming the passage portion 601. That is, the passage diameter D5 of the passage portion 601 is formed smaller than the passage diameter D3 of the passage portion 602. In addition, after the passage portion 602 is formed, the filter insertion portion 602a is formed using a drill having a larger diameter than the drill that forms the passage portion 602.

  Incidentally, the passage portion 602 may be formed after the passage portion 601 is formed. In this case, the drill that forms the passage portion 602 is a drill having a smaller diameter than the drill that forms the passage portion 601, and the passage diameter D3 of the passage portion 602 is formed smaller than the passage diameter D5 of the passage portion 601. Is desirable.

  Next, a recess 45 is formed by drilling from the end surface on the side opposite to the injection hole of the body 4. Thereafter, the upstream passage 81 is formed so as to communicate with the passage portion 602 by inserting a drill into the recess 45 and drilling from the bottom surface of the recess 45 toward the passage portion 602. Accordingly, the virtual extension line M (see FIG. 2) of the downstream passage 82 is positioned inside the opening 45c of the recess 45 so that the drill blade can be inserted into the recess 45 to process the downstream passage 82. Thus, the positional relationship between the downstream passage 82 and the recess 45 is set.

  A drill having a smaller diameter than the drill forming the passage portion 602 is used as the drill forming the upstream passage 81. Next, a drill having a diameter larger than that of the drill forming the upstream passage 81 is inserted into the recess 45 and drilled from the bottom surface of the recess 45 with the large diameter drill. The downstream passage 82 is formed by enlarging the passage diameter.

  Here, the stepped portion 6b, which is a connection point between the upstream side passage 81 and the downstream side passage 82, has a stepped shape in which the passage diameter rapidly increases, and a portion of the body 4 located around the stepped portion 6b ( The protruding portion indicated by reference numeral 4b has a protruding shape. In addition, as described above, a portion of the body 4 located around the branch portion 6a (a protruding portion indicated by reference numeral 4a) has a protruding shape. Therefore, when the upstream side passage 81, the downstream side passage 82, and the passage portion 602 are drilled, there is a concern that burrs may be generated in the protruding portions 4a and 4b.

  In view of this concern, in this embodiment, the electrolytic deburring device (not shown) is used to deburr the tips of the protrusions 4a and 4b by electrolytic processing. Specifically, an electrode of an electrolytic deburring device is inserted from the recessed portion 45 side of the branch passage 8 or the filter insertion portion 602a side of the high-pressure passage 6, and an electric current is passed between the protruding portions 4a and 4b and the electrodes. Dissolve and remove burrs.

  As described above, according to the present embodiment, the branch passage 8 includes the upstream passage 81 including the branch portion 6 a communicating with the high-pressure passage 6 and the downstream passage 82 located on the downstream side of the upstream passage 81. Then, the passage diameter D 1 of the upstream passage 81 is made smaller than the passage diameter D 2 of the downstream passage 82.

  Therefore, as compared with the case where the entire passage diameter of the branch passage 8 is the passage diameter D2 of the downstream passage 82 as in the fuel injection valve indicated by reference sign a2 in FIG. 3, the high pressure passage 6 (passage portion 602) of the body 4 is compared. ) And the branch passage 8 (upstream side passage 81) intersect with each other (the protruding portion 4a) can be improved in strength. FIG. 3B is a numerical analysis result showing the relationship between the stress generated in the protruding portion 4a and the allowable stress. Even if the pressure of the high-pressure fuel is the same, the stress generated in the body 4 of the fuel injection valve a2 is shown. As a result, the stress generated in the body 4 of the fuel injection valve a3 according to the present embodiment is smaller.

  Further, compared to the case where the entire passage diameter of the branch passage 8 is set to the passage diameter D1 of the upstream passage 81 as in the fuel injection valve indicated by reference numeral a1 in FIG. 3, it is superimposed on the detection signal output from the mold IC 54. The amplitude of pulsation can be reduced. As described above, the pressure fluctuation waveform caused by the fuel injection can be acquired by the fuel pressure sensor 50. However, higher-frequency noise is superimposed on the obtained fluctuation waveform. FIG. 3C shows a result obtained by calculating a waveform obtained by extracting the high-frequency noise by numerical analysis. Even when the pressure of the high pressure fuel is the same, the amplitude of the high frequency noise generated in the case of the fuel injection valve a3 according to the present embodiment is smaller than the amplitude of the high frequency noise generated in the case of the fuel injection valve a1. The result is shown.

  As described above, according to the present embodiment, it is possible to realize both the reduction of high-frequency noise superimposed on the detection signal of the fuel pressure sensor 50 and the securing of strength at the protruding portion 4a of the body 4.

  Furthermore, according to this embodiment, the effects listed below are also exhibited.

  The passage diameter D1 of the upstream passage 81 is smaller than the passage diameter D3 of the passage portion 602. Therefore, it is possible to reduce the pressure loss generated in the passage portion 602 by sufficiently increasing the passage diameter D3 of the passage portion 602. Further, after the passage portion 602 is drilled, the upstream side passage 81 is formed by drilling toward the passage portion 602. Even if the drilling position of the upstream side passage 81 is slightly shifted in the radial direction, The possibility that the side passage 81 protrudes from the passage portion 602 can be reduced. That is, it is possible to absorb the machining position variation when the upstream side passage 81 is drilled, and the workability of the upstream side passage 81 and the passage portion 602 can be improved.

  Since the intersection angle α between the central axis θ1 of the upstream passage 81 and the central axis θ2 of the passage portion 602 is 90 degrees and the protrusion tip angle β of the protrusion 4a is 90 degrees, the protrusion 4a of the body 4 is It is possible to avoid a shape protruding at an acute angle. Therefore, the strength of the protruding portion 4a of the body 4 can be improved.

  The passage length L2 of the downstream passage 82 is longer than the passage length L1 of the upstream passage 81. Further, the passage length L <b> 2 of the downstream passage 82 is longer than the passage diameter D <b> 2 of the downstream passage 82. Therefore, the volume in the downstream passage 82 can be sufficiently increased, and the high-frequency noise superimposed on the detection signal can be sufficiently reduced.

(Second Embodiment)
In the first embodiment, the stepped portion 6b, which is a connection point between the upstream side passage 81 and the downstream side passage 82, is formed in a stepped shape in which the passage diameter rapidly increases. On the other hand, in the present embodiment shown in FIG. 4, the upstream passage 81 and the downstream passage 82 are connected by a tapered passage 83. The tapered passage 83 is formed in a tapered shape so that the diameter of the passage gradually decreases from the communication portion 83 a with the downstream passage 82 to the communication portion 83 b with the upstream passage 81. The upstream side passage 81 and the downstream side passage 82 have a shape in which a predetermined passage length is formed with a constant passage diameter.

  The passage diameter D1 of the branch portion 6a is smaller than the passage diameter D3 of the passage portion 602. Further, the passage length of the downstream passage 82 is longer than the passage length of the upstream passage 81. The passage length L <b> 2 of the downstream passage 82 is longer than the passage diameter D <b> 2 of the downstream passage 82. The central axis of the taper passage 83 coincides with the central axes of the upstream passage 81 and the downstream passage 82. The intersection angle between the central axis of the upstream passage 81 and the central axis of the passage portion 602 is 90 degrees.

  FIG. 5 is a view showing a side surface of the drill blade DL used when drilling the branch passage 8. In the case of this embodiment in which the upstream passage 81 and the downstream passage 82 are communicated with each other by the taper passage 83, when the downstream passage 82 is drilled after the upstream passage 81 is drilled, for example, a tip angle (see FIG. The drill blade DL shown in FIG. 5 may be used when the reference γ in FIG. 5 is smaller than 180 ° (preferably smaller than 90 °). That is, the taper passage 83 may be processed by the tip portion DL1 of the drill blade DL, and the downstream passage 82 may be processed by the side surface portion DL2 of the drill blade.

  In order to form the stepped shape as in the first embodiment, when the downstream passage 82 is drilled after the upstream passage 81 is drilled, for example, a tip angle (see symbol γ in FIG. 5). A drill blade of about 180 ° may be used.

  As described above, according to this embodiment, the pressure loss generated in the branch passage 8 can be reduced as compared with the case where the tapered passage 83 is abolished and formed in a stepped shape as in the first embodiment. Therefore, when the fuel pressure fluctuation is detected by the fuel pressure sensor 50, the fuel pressure fluctuation caused by the injection can be sensitively detected, and the pressure fluctuation waveform can be acquired with high accuracy.

(Third embodiment)
In the second embodiment, the branch passage 8 branched from the passage portion 602 includes the upstream passage 81, the downstream passage 82, and the taper passage 83. On the other hand, in the present embodiment shown in FIG. 6, the upstream passage 81 is eliminated, and the branch passage 8 is constituted by the downstream passage 82 and the taper passage 83.

  That is, the upstream end portion of the tapered passage 83 and a portion communicating with the high-pressure passage 6 (passage portion 602) in the tapered passage 83 corresponds to the branch portion 6a. Further, a portion from the upstream end portion to the downstream end portion of the downstream passage 82 and a portion from a portion communicating with the upstream passage 81 to a portion communicating with the recess 45 in the downstream passage 82 is a downstream portion. This corresponds to 6b. The downstream passage 82 has a shape in which a predetermined passage length is formed with a constant passage diameter.

  The passage diameter D1 of the branch portion 6a is smaller than the passage diameter D3 of the passage portion 602. Further, the passage length L <b> 2 of the downstream passage 82 is longer than the passage length L <b> 3 of the taper passage 83. The central axis of the taper passage 83 coincides with the central axis of the downstream passage 82. The intersection angle between the central axis of the tapered passage 83 and the central axis of the passage portion 602 is 90 degrees.

  In the present embodiment, the downstream passage 82 is drilled after the passage portion 602 is drilled. When the downstream passage 82 is drilled, the drill blade DL is used by using the drill blade DL shown in FIG. It is only necessary to process the tapered passage 83 at the front end portion DL1, and at this time, the downstream passage 82 is processed by the side surface portion DL2 of the drill blade.

  As described above, according to this embodiment, the pressure loss generated in the branch passage 8 can be reduced as compared with the case where the tapered passage 83 is abolished and formed in a stepped shape as in the first embodiment. Therefore, when the fuel pressure fluctuation is detected by the fuel pressure sensor 50, the fuel pressure fluctuation caused by the injection can be sensitively detected, and the pressure fluctuation waveform can be acquired with high accuracy.

  Furthermore, according to the present embodiment, the downstream passage 82 can be processed by the side surface portion DL2 of the drill blade, and at the same time, the tapered passage 83 can be processed by the tip portion DL1 of the drill blade. Therefore, the downstream side passage 82 and the taper passage 83 can be simultaneously formed by one drilling. On the other hand, in the second embodiment, since the upstream passage 81 and the downstream passage 82 must be processed using separate drill blades, the workability of the branch passage 8 can be improved according to this embodiment.

(Fourth embodiment)
In the present embodiment shown in FIG. 7, the upstream passage 81 and the downstream passage 82 having a predetermined passage length and a constant passage diameter are eliminated, and the entire branch passage 8 is formed by a tapered passage 830. That is, the tapered passage 830 is formed in a tapered shape in which the passage diameter gradually decreases from the recess 45 to the passage portion 602.

  Note that the upstream end portion of the tapered passage 830 and the portion of the tapered passage 830 that communicates with the high-pressure passage 6 (passage portion 602) corresponds to the branch portion 6a. Further, the downstream end portion of the tapered passage 830 and the portion communicating with the recess 45 in the tapered passage 830 corresponds to the downstream portion 6b.

  In this embodiment, the downstream passage 82 is drilled after the passage portion 602 is drilled. However, the cutting edge angle of the third embodiment is larger than that of the drill blade used for drilling the downstream passage 82 in the third embodiment. The tapered passage 830 is drilled using a drill blade.

  As described above, according to the present embodiment, the upstream passage 81 and the downstream passage 82 formed with a predetermined passage length with a constant passage diameter are eliminated, and the entire branch passage 8 is formed by the tapered passage 830. The pressure loss generated in the branch passage 8 can be reduced. Therefore, when the fuel pressure fluctuation is detected by the fuel pressure sensor 50, the fuel pressure fluctuation caused by the injection can be sensitively detected, and the pressure fluctuation waveform can be acquired with high accuracy.

  According to the present embodiment, the taper passage 830 can be drilled at a time using one type of drill blade, or the drilling can be performed in multiple times using two or more types of drill blades. May be.

(Fifth embodiment)
In the first embodiment, the central axis θ1 of the upstream passage 81 and the central axis θ1 of the downstream passage 82 coincide with each other, whereas in the present embodiment shown in FIG. The branch passage 8 is formed so that the central axis θ3 of the downstream passage 82 intersects. That is, the branch passage 8 is formed in a shape in which the communication portion between the upstream passage 81 and the downstream passage 82 is bent. The central axis of the passage portion 601 coincides with the central axis θ1 of the upstream passage 81. Therefore, the upstream passage 81 is formed by drilling simultaneously with the passage portion 601.

  As described above, also according to the present embodiment, the passage diameter D1 of the upstream passage 81 is made smaller than the passage diameter D2 of the downstream passage 82, so that the high frequency noise superimposed on the detection signal of the fuel pressure sensor 50 can be reduced. It is possible to realize both the securing of the strength in the protruding portion 4a.

(Sixth embodiment)
In the first to fifth embodiments, the high-pressure port 43 is formed on the outer peripheral surface of the body 4 and fuel is supplied from the side surface of the body 4 to the high-pressure passage 6, whereas in the present embodiment shown in FIG. The high pressure port 43 is formed on the upper end surface (the end surface opposite to the injection hole) of the body 4, and fuel is supplied from the upper end surface of the body 4 to the high pressure passage 6. A recess 45 to be inserted into the stem 51 is formed on the side surface of the body 4.

  The high-pressure passage 6 has a shape extending linearly in the fuel injection valve axial direction (vertical direction in FIG. 9), and the branch passage 8 has a shape extending linearly in the fuel injection valve radial direction (left-right direction in FIG. 9). is there. The branch passage 8 includes an upstream passage 81 having a predetermined passage length and a constant passage diameter, and a downstream passage 82 having a predetermined passage length and a constant passage diameter. The upstream end of the upstream passage 81 and the portion of the upstream passage 81 that communicates with the high-pressure passage 6 corresponds to the branch portion 6a. Further, a portion from the upstream end portion to the downstream end portion of the downstream passage 82 and a portion from a portion communicating with the upstream passage 81 to a portion communicating with the recess 45 in the downstream passage 82 is a downstream portion. This corresponds to 6b.

  The passage diameter of the upstream passage 81 is smaller than the passage diameter of the downstream passage 82. The intersection angle between the central axis of the upstream passage 81 and the central axis of the high-pressure passage 6 is 90 degrees.

  As described above, also according to the present embodiment, the passage diameter of the upstream passage 81 is made smaller than the passage diameter of the downstream passage 82, so that the high-frequency noise superimposed on the detection signal of the fuel pressure sensor 50 can be reduced and the protruding portion of the body 4 can be reduced. It is possible to achieve both strength securing in 4a.

  a3 ... Fuel injection valve, 4 ... Body, 4a ... Projection (intersection), 6 (601, 602) ... High pressure passage, 6a ... Branch portion, 6b ... Downstream portion, 8 ... Branch passage, 50 ... Fuel pressure sensor, 81 (8) ... Upstream side passage, 82 (8) ... Downstream side passage, 83 (8) ... Tapered passage, D1 ... Path diameter of upstream side passage, D2 ... Passage diameter of downstream side passage, α ... Intersection angle.

Claims (8)

In a fuel injection valve mounted on an internal combustion engine and injecting fuel from a nozzle hole,
A body that internally forms a high-pressure passage through which high-pressure fuel flows to the nozzle hole;
A fuel pressure sensor attached to the body for detecting the pressure of the high-pressure fuel;
With
The body is formed with a branch passage that branches from the high-pressure passage and guides the high-pressure fuel to the fuel pressure sensor.
A passage diameter of a branch portion communicating with the high-pressure passage among the branch passages is made smaller than a passage diameter of a downstream portion of the branch passage located on the fuel pressure sensor side with respect to the branch portion. Fuel injection valve. The branch passage has an upstream side passage having a predetermined passage length including the branch portion and a constant passage diameter, and a downstream passage having a predetermined passage length including the downstream portion and a constant passage diameter. Configured
The fuel injection valve according to claim 1, wherein a passage diameter of the downstream passage is smaller than a passage diameter of the upstream passage. The branch passage has a tapered passage communicating with the downstream passage and the upstream passage,
3. The fuel according to claim 2, wherein the tapered passage is formed in a tapered shape so that a passage diameter gradually decreases from a communication portion with the downstream passage to a communication portion with the upstream passage. Injection valve. The branch passage includes a downstream passage formed with a predetermined passage length including the downstream portion with a constant passage diameter, and a tapered passage communicating with the downstream passage and the branch portion.
2. The fuel injection according to claim 1, wherein the tapered passage is formed in a tapered shape so that a passage diameter gradually decreases from a communicating portion with the downstream passage to a communicating portion with the branch portion. valve.   2. The fuel injection valve according to claim 1, wherein the branch passage is formed in a tapered shape so that a passage diameter gradually decreases from a communication portion with the fuel pressure sensor to a communication portion with the high pressure passage. .   The fuel injection valve according to any one of claims 1 to 5, wherein a passage diameter of the branch portion is equal to or smaller than a passage diameter of the high-pressure passage. The branch passage is branched from a portion extending linearly in the high-pressure passage,
The fuel injection valve according to claim 6, wherein a passage diameter of the branch portion is smaller than a passage diameter of the high-pressure passage.   The intersection angle between a passage length direction of a portion including the branch portion of the branch passage and a passage length direction of a portion communicating with the branch portion of the high-pressure passage is set to approximately 90 degrees. Item 8. The fuel injection valve according to any one of Items 1 to 7.

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