JP6988196B2 - Fuel injection device - Google Patents

Description

The disclosure by this specification relates to a fuel injection device that injects fuel from a injection hole.

Conventionally, as a kind of fuel injection device, for example, in Patent Document 1, a housing provided with a control chamber and a valve body accommodating chamber, a needle displaced by the fuel pressure of the control chamber, and a valve body accommodating chamber are accommodated. A configuration with a valve body is disclosed. The valve body accommodating chamber is communicated with the control chamber by a branch passage, and is communicated with the low pressure side by a low pressure fuel passage.

JP-A-2017-75532

In the fuel injection device of Patent Document 1, the inflow opening of the branch passage facing the valve body accommodating chamber is provided so that its central axis intersects with the central axis of the valve body. Similarly, the outflow opening of the low pressure fuel passage facing the valve body accommodating chamber is also provided so that its central axis intersects the central axis of the valve body. The inventors of the present disclosure show that in the fuel injection device having the configuration of Patent Document 1, the fuel pressure around the valve body is biased during the period when the fuel flows out from the valve body accommodating chamber to the low pressure side. Newly discovered.

The deviation of the fuel pressure around the valve body as described above causes a force in the eccentric direction to act on the valve body. When the attitude of the valve body is tilted due to the force in the eccentric direction, the fuel flow rate in the control chamber flowing out through the valve body accommodating chamber and the pressure drop in the control chamber become unstable. As a result, the accuracy of the injection amount of the fuel injected from the injection hole may be deteriorated. Therefore, it is desirable to suppress the inclination of the posture of the valve body.

It is an object of the present disclosure to provide a fuel injection device capable of laterally displacing a valve body in a stable posture.

In order to achieve the above object, one aspect disclosed is that the control chamber (35), the valve chamber (36), and the fuel in the valve chamber, in which the injection hole (38) for injecting fuel is formed and filled with fuel, are used. The outflowing low pressure chamber (37), the first flow path (70, 270, 370) communicating the control chamber and the valve chamber, and the second flow path (80) communicating the valve chamber and the low pressure chamber through the throttle section. The body (20) provided inside, the needle (50) that is displaced by the fluctuation of the fuel pressure in the control chamber and opens and closes the injection hole, and the needle (50) that is housed in the valve chamber in a state where it can be displaced in the axial direction, are housed in the valve chamber. columnar valve body seating surface (61) Ru is away seated on the seat surface portion (27) and (60), to drive the valve body by stretching operation, and a state in which the valve chamber and the low pressure chamber by a second flow path is communicated A drive unit (40) for switching between a state in which communication between the valve chamber and the low pressure chamber by the second flow path is cut off, and an end portion on the valve chamber side in the first flow path located on the upstream side of the seating surface. both the inlet opening (71,271,371) and the seating surface of the downstream located side outflow opening comprising a valve chamber side of the end portion in the second flow path (81) comprising the, in the circumferential direction around the periphery of the valve body It is a fuel injection device provided at a position shifted to the outer peripheral side with respect to the central axis (CL1) of the valve body in a direction in which a swirling flow (SF) is generated in the fuel in the valve chamber.

In this embodiment, at least one of the inflow opening and the outflow opening is provided at a position deviated from the central axis of the valve body toward the outer peripheral side in a direction that causes a swirling flow in the circumferential direction. Therefore, during the period when the fuel flows out from the valve chamber to the low pressure chamber, a circumferential fuel flow around the valve body is caused. Such a swirling flow of fuel reduces the deviation of the fuel pressure around the valve body. As a result, the force in the eccentric direction caused by the imbalance of the fuel pressure in the circumferential direction is suppressed, so that the valve body can be displaced in the axial direction in a stable posture.

The reference numbers in parentheses are merely examples of the correspondence with the specific configuration in the embodiment described later, and do not limit the technical scope at all.

It is a figure which shows the whole structure of the fuel supply system including the fuel injection device and the control device by 1st Embodiment. It is a vertical sectional view of a fuel injection device. It is an enlarged view which expanded the region III of FIG. 2, and is the vertical sectional view which shows the detail of the vicinity of a valve chamber. FIG. 3 is a sectional view taken along line IV-IV of FIG. FIG. 3 is a sectional view taken along line VV of FIG. It is a figure for demonstrating the effect of a swirling flow, and is the figure which shows an example of the pressure distribution in the same place as FIG. 7 when there is no swirling flow. It is a figure which shows an example of the pressure distribution when there is a swirl flow about the region VII of FIG. It is a figure which shows the effect of reducing the oil pressure by a swirling flow. It is a figure which shows the control communication passage by 2nd Embodiment. It is a vertical cross-sectional view which shows the detail of the vicinity of the valve chamber of the fuel injection apparatus by 3rd Embodiment. FIG. 10 is a cross-sectional view taken along the line XI-XI of FIG. It is a vertical sectional view which shows the detail of the vicinity of the valve chamber of the fuel injection apparatus according to 4th Embodiment.

Hereinafter, a plurality of embodiments of the present disclosure will be described with reference to the drawings. By assigning the same reference numerals to the corresponding components in each embodiment, duplicate description may be omitted. When only a part of the configuration is described in each embodiment, the configuration of the other embodiment described above can be applied to the other parts of the configuration. Further, not only the combination of the configurations specified in the description of each embodiment but also the configurations of a plurality of embodiments can be partially combined even if the combination is not specified. Further, an unspecified combination of the configurations described in the plurality of embodiments and modifications is also disclosed by the following description.

(First Embodiment)
The fuel injection device 10 according to the first embodiment of the present disclosure is used in the fuel supply system 1 shown in FIG. The fuel injection device 10 supplies the fuel stored in the fuel tank 4 to each combustion chamber 2b of the diesel engine (hereinafter, “engine 2”) which is an internal combustion engine. The fuel supply system 1 includes a feed pump 5, a high-pressure fuel pump 6, a common rail 3, a control device 9, and the like together with a fuel injection device 10.

The feed pump 5 is, for example, a trochoidal electric pump. The feed pump 5 is built in the high pressure fuel pump 6. The feed pump 5 pumps light oil as fuel stored in the fuel tank 4 to the high-pressure fuel pump 6. The feed pump 5 may be separate from the high-pressure fuel pump 6 and may be arranged inside, for example, the fuel tank 4.

The high-pressure fuel pump 6 is, for example, a plunger type pump. The high-pressure fuel pump 6 is driven by the output shaft of the engine 2. The high-pressure fuel pump 6 is connected to the common rail 3 by a fuel pipe 6a. The high-pressure fuel pump 6 further boosts the fuel supplied by the feed pump 5 and supplies it to the common rail 3 as high-pressure fuel.

The common rail 3 is connected to a plurality of fuel injection devices 10 via a high-pressure fuel pipe 3b. The common rail 3 is connected to the fuel tank 4 via the surplus fuel pipe 8a. The common rail 3 temporarily stores the high-pressure fuel supplied from the high-pressure fuel pump 6 and distributes the high-pressure fuel to each fuel injection device 10 while maintaining the pressure. The common rail 3 is provided with a pressure reducing valve 8. The pressure reducing valve 8 discharges the surplus fuel to the surplus fuel pipe 8a when the fuel pressure of the common rail 3 is higher than the target pressure.

The control device 9 is an electronic control unit including an ECU (Electronic Control Unit) 9a and an EDU (Electronic Driver Unit) 9b. The control device 9 is electrically connected to each fuel injection device 10. The control device 9 controls the injection of fuel by each fuel injection device 10 according to the operating state of the engine 2.

The ECU 9a includes an arithmetic circuit mainly composed of a microcomputer or a microcontroller. The arithmetic circuit includes a processor, RAM, and a rewritable non-volatile memory device. The EDU 9b applies a drive voltage to the drive unit 40 (see FIG. 2) of the fuel injection device 10 based on the command signal input from the ECU 9a.

The fuel injection device 10 is attached to the head member 2a in a state of being inserted into the insertion hole of the head member 2a forming the combustion chamber 2b. The fuel injection device 10 directly injects high-pressure fuel supplied through the high-pressure fuel pipe 3b from the injection hole 38 toward the combustion chamber 2b. The fuel injection device 10 has a valve structure for controlling the injection of fuel from the injection hole 38. The fuel injection device 10 uses a part of the high-pressure fuel to open and close the injection hole 38. A part of the fuel supplied to the fuel injection device 10 is returned to the fuel tank 4 through the return pipe 8b and the surplus fuel pipe 8a.

As shown in FIGS. 2 and 3, the fuel injection device 10 includes a valve body 20, a nozzle needle 50, a drive unit 40, a valve body 60, and a coil spring 68.

The valve body 20 is configured by combining a plurality of metal members such as an injector body member 21, a valve body member 22, an orifice forming member 23, a nozzle body member 24, a retaining nut 25, and a needle cylinder 26. A jet hole 38 is formed in the valve body 20. In addition, a high-pressure fuel passage 31, a high-pressure chamber 31a, a supply communication passage 32, a low-pressure chamber 37, a control chamber 35, and a valve chamber 36 are provided inside the valve body 20.

The injection hole 38 is formed at the tip end portion in the insertion direction in the valve body 20 inserted into the head member 2a (see FIG. 1). The injection hole 38 is exposed to the combustion chamber 2b (see FIG. 1). The tip of the valve body 20 is formed in a conical or hemispherical shape. A plurality of injection holes 38 are provided radially from the inside to the outside of the valve body 20. Each injection hole 38 injects high-pressure fuel toward the combustion chamber 2b. The high-pressure fuel is atomized by passing through the injection hole 38, and is easily mixed with air.

The high-pressure fuel passage 31 is formed over the injector turbo day member 21, the valve body member 22, and the orifice forming member 23. The high-pressure fuel passage 31 is connected to the high-pressure fuel pipe 3b (see FIG. 1). The high-pressure fuel passage 31 supplies the high-pressure fuel supplied from the common rail 3 (see FIG. 1) to the high-pressure chamber 31a through the high-pressure fuel pipe 3b.

The high pressure chamber 31a is a space formed in a columnar shape on the nozzle body member 24. The nozzle needle 50 and the needle cylinder 26 are housed in the high pressure chamber 31a. The high pressure chamber 31a is connected to the high pressure fuel passage 31. The high pressure chamber 31a is filled with high pressure fuel supplied through the high pressure fuel passage 31. The high-pressure chamber 31a distributes high-pressure fuel to the injection hole 38.

The supply communication passage 32 is a fuel passage that communicates the high pressure chamber 31a and the valve chamber 36. An in orifice 32a is formed in the supply communication passage 32. The in orifice 32a limits the flow rate of fuel flowing from the high pressure chamber 31a into the valve chamber 36 in a state where the high pressure chamber 31a and the valve chamber 36 are connected by the supply communication passage 32.

The low pressure chamber 37 is formed in the injector turbo day member 21. The low pressure chamber 37 is connected to the return pipe 8b (see FIG. 1), and the surplus fuel is circulated to the return pipe 8b. The low pressure chamber 37 is filled with fuel having a lower pressure than that of the high pressure chamber 31a. The fuel of the control chamber 35 and the valve chamber 36 flows out to the low pressure chamber 37.

The control chamber 35 is a columnar space partitioned by an orifice forming member 23, a needle cylinder 26, a nozzle needle 50, and the like. The control chamber 35 is located on the opposite side of the injection hole 38 with the nozzle needle 50 interposed therebetween. Fuel is supplied to the control chamber 35 via the supply communication passage 32, the valve chamber 36, and the control communication passage 70. The control chamber 35 is filled with fuel.

The valve chamber 36 is a columnar space partitioned by a valve body accommodating hole 39 provided in the valve body member 22 and an upper end surface of the orifice forming member 23. The valve chamber 36 is provided between the control chamber 35 and the low pressure chamber 37. A valve body 60 and a coil spring 68 are housed in the valve chamber 36. The valve chamber 36 is filled with fuel supplied from the high pressure chamber 31a through the supply communication passage 32. The fuel in the valve chamber 36 passes through the low pressure communication passage 80 and is discharged to the low pressure chamber 37.

The valve chamber 36 is partitioned by a partition wall 36a including an inner peripheral wall surface 36c, a bottom wall surface 36b, and a top wall surface 36d. The inner peripheral wall surface 36c is a cylindrical wall surface forming the valve body accommodating hole 39. The inner peripheral wall surface 36c surrounds the valve body 60 while ensuring a radial gap between the inner peripheral wall surface 36c and the valve body 60.

The bottom wall surface 36b is provided in a circular shape on the upper end surface of the orifice forming member 23. A supply opening 32b and a lower seat surface portion 28 are formed on the bottom wall surface 36b. The supply opening 32b is one end of the supply communication passage 32. The supply opening 32b is circularly opened in the center of the bottom wall surface 36b. The supply opening 32b allows high-pressure fuel that has passed through the in-orifice 32a to flow into the valve chamber 36. The lower seat surface portion 28 faces the bottom surface of the valve body 60 in the axial direction of the valve body 60. The lower seat surface portion 28 is formed in an annular shape surrounding the periphery of the supply opening 32b. A valve body 60 displaced in the axial direction is taken off and seated on the lower seat surface portion 28.

The top wall surface 36d is provided in a circular shape on the bottom wall of the valve body accommodating hole 39 provided in the valve body member 22. A pin accommodating hole 22a formed in a cylindrical hole shape in the valve body member 22 is connected to the top wall surface 36d. A connection opening 22c and an upper seat surface portion 27 are formed on the top wall surface 36d. The connection opening 22c is one end of the pin accommodating hole 22a. The connection opening 22c is circularly opened in the center of the top wall surface 36d. The connection opening 22c allows the fuel in the valve chamber 36 to flow out into the pin accommodating hole 22a. The upper seat surface portion 27 faces the top surface of the valve body 60 in the axial direction of the valve body 60. The upper sheet surface portion 27 is formed in an inner tapered surface shape surrounding the periphery of the connection opening 22c. A valve body 60 that is displaced in the axial direction is detached and seated on the upper seat surface portion 27.

The nozzle needle 50 is formed in a cylindrical shape by a metal material. The tip of the nozzle needle 50 on the injection hole 38 side is formed in a conical shape. The nozzle needle 50 is housed in the high-pressure chamber 31a, and receives a force in the direction of opening the injection hole 38 (hereinafter, “valve opening direction”) from the high-pressure fuel in the high-pressure chamber 31a. The nozzle needle 50 is formed with a needle pressure receiving surface 51.

The needle pressure receiving surface 51 is formed on the axial end surface of the nozzle needle 50 facing the control chamber 35. The needle pressure receiving surface 51 receives a force in the direction of closing the injection hole 38 (hereinafter, “valve closing direction”) from the high-pressure fuel filled in the control chamber 35. In addition, the nozzle needle 50 is urged in the valve closing direction by a needle spring 53 formed in a cylindrical spiral shape.

The nozzle needle 50 is pushed up by the fuel in the high pressure chamber 31a due to the depressurization of the control chamber 35, and is displaced toward the valve opening direction. As a result, the high-pressure fuel filled in the high-pressure chamber 31a is injected from the injection hole 38 toward the combustion chamber 2b (see FIG. 1). On the other hand, according to the pressure recovery of the control chamber 35, the nozzle needle 50 is pushed down in the valve closing direction. As a result, fuel injection from the injection hole 38 is stopped. In this way, the nozzle needle 50 is displaced relative to the valve body 20 along the axial direction due to the fluctuation of the fuel pressure in the control chamber 35, and opens and closes the injection hole 38.

The drive unit 40 drives the valve body 60. The drive unit 40 is composed of a piezo actuator 41 having a laminate of piezoelectric elements, a drive transmission pin 42, and the like. The piezoelectric element laminate of the piezo actuator 41 is, for example, a laminate in which layers called PZT (PbZrTiO3) and thin electrode layers are alternately stacked. The drive voltage output from the control device 9 (see FIG. 1) is input to the piezo actuator 41. The piezo actuator 41 expands and contracts based on the input of the drive voltage due to the inverse piezoelectric effect, which is a characteristic of the piezo element.

The drive transmission pin 42 is a pressing shaft portion that transmits the expansion / contraction operation of the piezoelectric element laminated body to the valve body 60. The drive transmission pin 42 is accommodated in the pin accommodating hole 22a. The tip end portion 42a of the drive transmission pin 42 is abutted against the center of the top surface of the valve body 60. The outer diameter of the tip portion 42a is made smaller than the inner diameter of the pin accommodating hole 22a. The gap between the tip portion 42a and the pin accommodating hole 22a functions as a passage for fuel flowing out of the valve chamber 36.

The drive unit 40 is displaced in the direction of protruding into the valve chamber 36 by the piezo actuator 41 extended by the accumulation of electric charges. Further, the drive unit 40 pulls the drive transmission pin 42 back to the pin accommodating hole 22a due to the contraction of the piezo actuator 41 due to the discharge of electric charge.

The valve body 60 is formed in a columnar shape as a whole by a metal material or the like. The valve body 60 has a cylindrical portion 60a and a hemispherical portion 60b. The columnar portion 60a is formed in a cylindrical shape and is located on the orifice forming member 23 side with respect to the hemispherical portion 60b. The hemispherical portion 60b is formed in a partially spherical shape that is convexly curved toward the connection opening 22c. The hemispherical portion 60b is located on the drive transmission pin 42 side with respect to the cylindrical portion 60a. The center of the hemispherical portion 60b is located on the central axis of the cylindrical portion 60a. The valve body 60 is housed in the valve chamber 36 so as to be coaxially arranged with the valve chamber 36 and the valve body member 22. With such an arrangement, the central axis CL1 of the valve body 60 passes through the center of the drive transmission pin 42, the connection opening 22c, and the supply opening 32b.

The valve body 60 is formed with an upper seating surface 61 and a lower seating surface 62. The upper seat surface 61 is provided at a position of the hemispherical portion 60b facing the upper seat surface portion 27. The upper seat surface 61 is pressed against the upper seat surface 27 in a state where the drive unit 40 is contracted. The underwear seating surface 62 is provided at a position of the bottom surface of the columnar portion 60a facing the lower seat surface portion 28. The underwear seat surface is pressed against the lower seat surface portion 28 in a state where the drive portion 40 is extended.

The coil spring 68 is an elastic member formed by spirally winding a linearly formed metal material. The coil spring 68 is housed in the valve chamber 36 in an arrangement substantially coaxial with the valve body 60. The coil spring 68 is arranged between the hemispherical portion 60b and the bottom wall surface 36b in a state of being compressed in the axial direction. A cylindrical portion 60a is housed on the inner peripheral side of the coil spring 68. The coil spring 68 urges the valve body 60 toward the drive transmission pin 42. The upper seat surface 61 is seated on the upper seat surface portion 27 by the urging force of the coil spring 68, and forms an oil tightness that prevents fuel from flowing out from the valve chamber 36.

Next, the details of the control communication passage 70 and the low pressure communication passage 80 formed in the valve body 20 will be further described with reference to FIGS. 3 to 5 and with reference to FIG. The control communication passage 70 and the low pressure communication passage 80 have a structure that causes a swirling flow SF in the fuel of the valve chamber 36.

The control communication passage 70 shown in FIGS. 3 and 4 is a fuel passage that communicates the control chamber 35 and the valve chamber 36. When the valve body 60 seats the upper seat surface 61 on the upper seat surface 27 due to the contraction operation of the drive unit 40, the control communication passage 70 distributes the fuel of the valve chamber 36 to the control chamber 35. On the other hand, when the valve body 60 seats the underwear seating surface 62 on the lower seating surface 28 by the extension operation of the drive unit 40, the control communication passage 70 circulates the fuel of the control chamber 35 to the valve chamber 36. The control communication passage 70 is provided with an inflow opening 71, a straight section 72, and a connecting section 73.

The inflow opening 71 is one end of both ends of the control communication passage 70 located on the valve chamber 36 side. The inflow opening 71 is open to the inner peripheral wall surface 36c and faces the valve chamber 36. The inflow opening 71 is provided at the lower edge portion of the inner peripheral wall surface 36c that is continuous with the bottom wall surface 36b. The inflow opening 71 is formed in a horizontally long shape in which the inner method along the circumferential direction of the valve body 60 is longer than the inner method along the axial direction of the valve body 60.

The inflow opening 71 has an inner circumference at a position deviated (eccentric) toward the outer periphery with respect to the central axis CL1 in a direction in which a circumferential swirling flow SF circulating around the valve body 60 is generated in the fuel of the valve chamber 36. It is open to the wall surface 36c. For the sake of detail, the virtual axis that defines the direction of the inflow opening 71 is referred to as the inflow axis AL1. The inflow axis AL1 is an axis that passes through the center of the inflow opening 71 and is along the extending direction of the connecting section 73. The inflow axis AL1 does not intersect the central axis CL1. The inflow axis AL1 has a twisted positional relationship with the central axis CL1 and is in a posture along the bottom wall surface 36b.

The straight section 72 is provided on the outer peripheral side of the valve chamber 36 in the orifice forming member 23. The straight section 72 is formed by a through hole that penetrates the orifice forming member 23 in the axial direction. The lower end of the straight section 72 faces the control room 35. The upper end of the straight section 72 is connected to the connecting section 73.

The connection section 73 is a section connecting the straight section 72 and the inflow opening 71 in the control communication passage 70. The connection section 73 is formed by a groove provided on the lower end surface of the valve body member 22. Assuming that the boundary between the outer wall surface 74 of the connecting section 73 and the inner peripheral wall surface 36c of the valve chamber 36 is the continuous portion 75, the connecting section 73 has a straight shape extending along the circumferential tangent TL at the continuous portion 75. Has been done. That is, the inflow axis AL1 of the inflow opening 71 is substantially parallel to the tangent TL at the continuous portion 75.

The low-pressure communication passage 80 shown in FIGS. 3 and 5 is a fuel passage that communicates the valve chamber 36 and the low-pressure chamber 37. The low-pressure communication passage 80 is provided at a position overlapping the control communication passage 70 in the axial direction of the valve body 60. The low pressure communication passage 80 is connected to the pin accommodating hole 22a provided in the valve body member 22. The low-pressure communication passage 80 circulates fuel from the pin accommodating hole 22a, which is a part of the valve chamber 36, toward the low-pressure chamber 37.

More specifically, when the valve body 60 seats the upper seat surface 61 on the upper seat surface 27 due to the contraction operation of the drive unit 40, the valve chamber 36 and the low pressure chamber 37 are in communication with each other by the low pressure communication passage 80. .. On the other hand, when the valve body 60 seats the lower seat surface 62 on the lower seat surface 28 due to the extension operation of the drive unit 40, the communication between the valve chamber 36 and the low pressure chamber 37 by the low pressure communication passage 80 is cut off. It becomes.

The low pressure communication passage 80 is provided with an out orifice 80a and an outflow opening 81. The out orifice 80a is a cylindrical hole-shaped throttle section provided in the low pressure communication passage 80. The out orifice 80a limits the flow rate of fuel flowing out from the valve chamber 36 to the low pressure chamber 37 through the low pressure communication passage 80.

The outflow opening 81 is located on the valve chamber 36 side of both ends of the low-voltage communication passage 80, and is one end facing the pin accommodating hole 22a. The outflow opening 81 serves as a flow path inlet of the out orifice 80a. The outflow opening 81 opens in a range that faces the tip portion 42a in the radial direction of the inner peripheral wall surface that partitions the pin accommodating hole 22a.

The outflow opening 81 is provided at a position deviated (eccentric) toward the outer peripheral side with respect to the central axis CL1 so as to generate a circumferential swirling flow SF circulating around the valve body 60 in the fuel of the valve chamber 36. ing. For the sake of detail, the virtual axis that defines the direction of the outflow opening 81 is referred to as the outflow axis AL2. The outflow axis AL2 is an axis that passes through the center of the outflow opening 81 and is along the axial direction of the out orifice 80a. Like the inflow axis AL1, the outflow axis AL2 does not intersect the central axis CL1 and has a twisted positional relationship with the central axis CL1. The outflow axis AL2 is positioned on the outer peripheral side with respect to the central axis CL1, and is in a posture inclined in a direction away from the central axis CL1 as it goes from the valve chamber 36 to the low pressure chamber 37.

The inflow opening 71 and the outflow opening 81 are provided on the same side with respect to the virtual vertical cross section VP of the valve body 60 including the central axis CL1. The virtual vertical cross section VP is defined in a posture in which one surface faces the high pressure fuel passage 31. The inflow opening 71 and the outflow opening 81 are located between the high pressure fuel passage 31 and the virtual vertical cross section VP. The direction of the swirling flow SF whose generation is promoted by the inflow opening 71 is the same as the direction of the swirling flow SF whose generation is promoted by the outflow opening 81. The swirling flow SF of the first embodiment is a fuel flow from the bottom wall surface 36b to the top wall surface 36d while circulating counterclockwise around the valve body 60 when viewed from the control chamber 35 side. The flow direction of this swirling flow SF is along the winding direction of the coil spring 68. In other words, the coil spring 68 is defined in its winding direction so as to follow the flow direction of the swirling flow SF.

The effect of such a swirling flow SF will be described with reference to FIGS. 6 to 8 and with reference to FIG.

When the swirling flow SF is not generated, the fuel flow from the inflow opening 71 to the outflow opening 81 mainly flows on one side of the valve body 60. Specifically, most of the fuel flows on the side where the inflow opening 71 and the outflow opening 81 open (hereinafter, "opening side AS") with respect to the central axis CL1 (virtual vertical cross section VP). Therefore, the flow velocity of the opening side AS with respect to the central axis CL1 is higher than the flow velocity of the opposite side (hereinafter, “anti-opening side UAS”). Therefore, as shown in FIG. 6, the fuel pressure between the upper seat surface 61 and the upper seat surface 27 becomes uneven in the circumferential direction, and the opening side AS becomes lower pressure than the anti-opening side UAS. As a result, the oil pressure PF in the eccentric direction (x-axis direction) that eccentricizes the valve body 60 toward the opening side AS where the pressure becomes low is generated.

On the other hand, when the swirling flow SF is generated, the flow from the inflow opening 71 to the outflow opening 81 goes around the valve body 60 and reaches the connection opening 22c. Therefore, the speed difference of the fuel flow is less likely to occur between the opening side AS and the non-opening side UAS. As a result, as shown in FIG. 7, the fuel pressure between the upper seat surface 61 and the upper seat surface 27 tends to be uniform in the circumferential direction. Therefore, the hydraulic pressure PF (see FIG. 6) that eccentricizes the valve body 60 can be reduced.

Further, the swirling flow SF can exert the effect of reducing the hydraulic pressure PF over the entire valve opening period of the valve body 60, as shown in FIG. More specifically, the peak of the hydraulic pressure PF generated after the valve opening of the valve body 60 is started can be suppressed by the swirling flow SF. In addition, in a certain form of the swirling flow SF, the oil pressure PF increases as the flow velocity increases as the opening degree of the valve body 60 increases. On the other hand, in a form with a swirling flow SF, as the opening degree of the valve body 60 increases, a strong and stable swirling flow SF is generated as the flow velocity increases. As a result, the hydraulic pressure PF acting on the valve body 60 can be reduced to a state close to substantially zero. As described above, the degree of contribution of the swirling flow SF to the suppression of the eccentricity of the valve body 60 increases as time elapses from the start of valve opening.

As described above, in the first embodiment, the inflow opening 71 and the outflow opening 81 are provided at positions deviated from the central axis CL1 toward the outer peripheral side in a direction that causes a swirling flow SF. Therefore, during the period when the fuel flows out from the valve chamber 36 to the low pressure chamber 37, a fuel flow in the circumferential direction around the valve body 60 is caused. According to such a swirling flow SF, the deviation of the fuel pressure around the valve body 60 is reduced. As a result, the oil pressure PF in the eccentric direction due to the imbalance of the fuel pressure in the circumferential direction is suppressed, so that the valve body 60 can be displaced in the axial direction in a stable posture.

Based on the above, the mode of pressure drop in the control chamber 35 due to the outflow of fuel to the low pressure chamber 37, and the mode of displacement of the nozzle needle 50 in the valve opening direction can also be stabilized. Therefore, the accuracy of the injection amount of the fuel injected from the injection hole 38 is improved.

In addition, in the first embodiment, the connection section 73 provided immediately before the inflow opening 71 has a shape extending along the tangent line TL in the circumferential direction of the inner peripheral wall surface 36c. By flowing through such a connection section 73, the fuel flowing into the valve chamber 36 flows smoothly along the inner peripheral wall surface 36c, and is guided to swivel around the valve body 60. As described above, according to the configuration in which the connection section 73 is provided, the swirling flow SF is likely to be generated, so that the force in the eccentric direction acting on the valve body 60 can be further reduced.

Further, in the first embodiment, the flow direction of the swirling flow SF is along the winding direction of the coil spring 68. Therefore, even if the coil spring 68 is housed in the valve chamber 36, the fuel can flow around the valve body 60 without being blocked by the wire rod of the coil spring 68. Based on the above, the effect of reducing the bias of the fuel pressure by the swirling flow SF is more likely to be exhibited.

Further, in the first embodiment, in addition to the inflow opening 71, the outflow opening 81 is also eccentric to the outer peripheral side, which promotes the generation of swirling flow SFs in the same direction as each other. With such a configuration, a stronger swirling flow SF may be generated in the fuel of the valve chamber 36. As a result, the eccentric oil pressure PF acting on the valve body 60 is more likely to be reduced.

In addition, in the first embodiment, the inflow opening 71 and the outflow opening 81 are provided on the same side with respect to the valve body 60 due to the arrangement of the control chamber 35, the valve chamber 36, the drive unit 40, and the like. There is. In such a form, the oil pressure PF in the eccentric direction is likely to occur (see FIG. 6). However, if the configuration is such that the swirling flow SF is generated, the pressure difference between the opening side AS and the non-opening side UA of the valve body 60 can be effectively eliminated even in a form in which the hydraulic pressure PF is likely to occur (FIG. 7). As described above, the configuration in which the swirling flow SF is generated by the layout of the inflow opening 71 and the outflow opening 81 is particularly suitable for the fuel injection device 10 in which the inflow opening 71 and the outflow opening 81 are located on the same side with respect to the valve body 60. That is.

In the first embodiment, the valve body 20 corresponds to the "body", the lower seat surface portion 28 corresponds to the "seat surface portion", the nozzle needle 50 corresponds to the "needle", and the control communication passage 70 corresponds to the "first". The low pressure communication passage 80 corresponds to the "one flow path" and corresponds to the "second flow path".

(Second embodiment)
The second embodiment shown in FIG. 9 is a modification of the first embodiment. In the second embodiment, the shape of the control communication passage 270 is different from that of the first embodiment. Hereinafter, the details of the control communication passage 270 of the second embodiment will be described with reference to FIGS. 9 and 3.

The connection section 273 connected to the inflow opening 271 in the control communication passage 270 has a shape curved in the circumferential direction along the inner peripheral wall surface 36c. The connection section 273 is formed by a curved groove portion provided in an arc shape on the outer peripheral side of the valve body accommodating hole 39 on the lower end surface of the valve body member 22. Also in the second embodiment, the inflow axis AL1 of the inflow opening 271 extends along the tangent TL of the continuous portion 75 between the outer wall surface 74 of the connecting section 273 and the inner peripheral wall surface 36c, and is substantially parallel to the tangent TL. Is. The fuel flowing through the connecting section 273 has a flow that tends to turn in the circumferential direction due to the curved shape of the connecting section 273. The fuel flowing into the valve chamber 36 from the inflow opening 271 swirls around the valve body 60 along the inner peripheral wall surface 36c due to the arrangement in which the inflow axis AL1 is displaced to the outer peripheral side with respect to the central axis CL1. Flow like.

The second embodiment described so far also has the same effect as that of the first embodiment, promotes the generation of swirling flow SF, and suppresses the eccentric oil pressure PF (see FIG. 6) acting on the valve body 60. Therefore, the valve body 60 can be displaced in a stable posture. In addition, in the second embodiment, due to the curved shape of the connection section 273 provided immediately before the inflow opening 271, the fuel flowing into the valve chamber 36 from the inflow opening 271 flows so as to swirl around the valve body 60 as it is. obtain. By creating a flow in the turning direction in advance in the connection section 273 in this way, the displacement posture of the valve body 60 becomes more stable.

(Third embodiment)
The third embodiment shown in FIGS. 10 and 11 is another modification of the first embodiment. In the control communication passage 370 of the third embodiment, the inflow opening 371 which is the end on the valve chamber 36 side is provided on the bottom wall surface 36b of the valve chamber 36. The inflow opening 371 opens in a substantially circular shape on the outer peripheral side of the lower seat surface portion 28 on which the valve body 60 is seated in the bottom wall surface 36b. The inflow opening 371 is provided at the outer edge portion of the bottom wall surface 36b facing the inner peripheral wall surface 36c.

The control communication passage 370 extends from the control chamber 35 (see FIG. 2) toward the inflow opening 371 in a posture inclined in the circumferential direction with respect to the central axis CL1. In addition, the control communication passage 370 is in a posture inclined toward the outer peripheral side with respect to the central axis CL1 so as to be separated from the central axis CL1 from the valve chamber 36 toward the control chamber 35. With the control communication passage 370 having such a shape, it is omitted to perform groove processing on the valve body member 22. The axis that defines the posture of the control communication passage 370 is the inflow axis AL1 that defines the direction of the inflow opening 71.

As in the third embodiment described so far, if the inflow opening 371 is opened in the bottom wall surface 36b and the control communication passage 370 is tilted with respect to the central axis CL1, the valve chamber is opened from the inflow opening 371. The fuel flowing into the 36 can be a swirling flow SF that swirls around the valve body 60. Based on the above, the valve body 60 has the same effect as that of the first embodiment, and the eccentric oil pressure PF (see FIG. 6) acting on the valve body 60 can be suppressed. Therefore, the valve body 60 has a stable posture in the axial direction. Can be displaced to. In the third embodiment, the lower seat surface portion 28 corresponds to the “seat surface portion”.

(Fourth Embodiment)
The fourth embodiment shown in FIG. 12 is still another modification of the first embodiment. In the fourth embodiment, the shape of the control communication passage 470 is different from that of the first embodiment. Specifically, in the fourth embodiment, the outflow opening 81 of the low pressure communication passage 80 contributes to the generation of the swirling flow SF as in the first embodiment. On the other hand, the inflow opening 471 of the control communication passage 470 does not substantially contribute to the generation of the swirling flow SF. The inflow axis AL101, which defines the direction of the inflow opening 471, has a posture along the bottom wall surface 36b and substantially intersects with the central axis CL1. The fuel flowing through the control communication passage 470 flows into the valve chamber 36 from the inflow opening 471 toward the central axis CL1.

Also in the above fourth embodiment, at least the outflow opening 81 is provided in an arrangement that promotes the generation of the swirling flow SF, so that the fuel flowing in from the inflow opening 471 gradually moves around the valve body 60 toward the connection opening 22c. Start to go around. Then, the fuel in the valve chamber 36 can reach the connection opening 22c with the movement in the circumferential direction with respect to the valve body 60. Therefore, the fourth embodiment also has the same effect as that of the first embodiment, and the valve body 60 is displaced in a stable posture by suppressing the eccentric oil pressure PF (see FIG. 6) acting on the valve body 60. It becomes possible.

(Other embodiments)
Although the plurality of embodiments of the present disclosure have been described above, the present disclosure is not construed as being limited to the above embodiments, and is applied to various embodiments and combinations without departing from the gist of the present disclosure. can do.

In the first modification of the first embodiment, the inflow opening of the control communication passage contributes to the generation of the swirling flow, while the outflow opening of the low pressure communication passage does not substantially contribute to the generation of the swirling flow. The outflow axis of the outflow opening substantially intersects the central axis of the valve body. Even in such a configuration, the fuel flowing into the valve chamber from the inflow opening can reach the connection opening with the movement in the circumferential direction with respect to the valve body. As a result, even in the first modification, the valve body can be displaced in the axial direction in a stable posture.

The coil spring of the above embodiment was arranged in the valve chamber so that the flow direction of the swirling flow and the winding direction coincide with each other. However, if the influence of the coil spring on the swirling flow is slight, the winding direction of the coil spring may be opposite to the flow direction of the swirling flow. Further, the coil spring may be omitted.

In the above embodiment, both the inflow opening and the outflow opening are arranged on the high pressure fuel passage side with respect to the valve body. However, the arrangement of the inflow opening and the outflow opening may be changed as appropriate. However, for example, when the valve chamber is viewed from the drive unit side, it is desirable that the inflow opening and the outflow opening are arranged so as to face each other in the circumferential direction.

For example, when the inflow opening is oriented in the clockwise direction with respect to the central axis, it is desirable that the outflow opening is oriented in the counterclockwise direction. Similarly, if the inflow opening is oriented counterclockwise with respect to the central axis, it is desirable that the outflow opening be oriented clockwise.

In the above embodiment, a piezo actuator having a laminated body of piezoelectric elements has been adopted as a drive unit. However, the drive unit may have a configuration having, for example, a magnetic electric actuator or the like.

In the above embodiment, an example in which the pressure control mechanism and the like of the present disclosure are applied to a fuel injection device that injects light oil as fuel has been described. However, the above pressure control mechanism can also be applied to a fuel injection device that injects a fuel other than light oil, for example, a liquefied gas fuel such as dimethyl ether.

10 Fuel injection device, 20 valve body, 28 lower seat surface (seat surface), 35 control room, 36 valve room, 36a partition wall, 36b bottom wall surface, 36c inner wall surface, 37 low pressure chamber, 38 nozzle hole, 40 drive unit , 50 nozzle needle (needle), 60 valve body, 68 coil spring, 70, 270, 370, 470 control communication passage (first flow path), 71,271,371,471 inflow opening, 73,273 connection section, 74 outside Wall surface, 75 continuous part, 80 low pressure continuous passage (second flow path), 81 outflow opening, CL1 center axis, AL2 outflow axis, TL tangent, VP virtual vertical section, SF swirl flow

Claims (7)

A control chamber (35) and a valve chamber (36) in which a jet hole (38) for injecting fuel is formed and filled with fuel, a low pressure chamber (37) from which fuel in the valve chamber flows out, the control chamber and the valve. A body (20) provided inside with a first flow path (70, 270, 370) communicating the chamber and a second flow path (80) communicating the valve chamber and the low pressure chamber via a throttle section. ,
A needle (50) that displaces due to fluctuations in the fuel pressure in the control chamber and opens and closes the injection hole.
Accommodated in the valve chamber displaceable in the axial direction, a columnar valve body seating surface (61) Ru is away seated on the seat surface portion (27) on said valve chamber (60),
The valve body is driven by the expansion / contraction operation, and the valve chamber and the low pressure chamber are in communication with each other by the second flow path, and the valve chamber and the low pressure chamber are in communication with each other by the second flow path. With a drive unit (40) that switches between
The inflow opening (71,271,371) located on the upstream side of the seating surface and serving as the end of the valve chamber side in the first flow path and the valve located on the downstream side of the seating surface in the second flow path. Both of the outflow openings (81), which are the ends on the chamber side, are oriented so as to generate a circumferential swirling flow (SF) around the valve body in the fuel of the valve chamber, and the central axis of the valve body (the central axis of the valve body (81). A fuel injection device provided at a position shifted to the outer peripheral side with respect to CL1). The inflow opening is opened in the inner peripheral wall surface (36c) surrounding the periphery of the valve body in the partition wall (36a) that divides the valve chamber.
The connection section (73) connected to the inflow opening in the first flow path is a circumferential tangent (TL) at the continuous portion (75) between the outer wall surface (74) of the connection section and the inner peripheral wall surface. The fuel injection device according to claim 1, which has a shape extending along the line. The inflow opening is opened in the inner peripheral wall surface (36c) surrounding the periphery of the valve body in the partition wall (36a) that divides the valve chamber.
The fuel injection device according to claim 1, wherein the connection section (273) connected to the inflow opening in the first flow path has a shape curved in the circumferential direction along the inner peripheral wall surface. The inflow opening is opened on the outer peripheral side of the seat surface portion (28) on which the valve body is seated in the bottom wall surface (36b) of the valve chamber.
The fuel injection device according to claim 1, wherein the first flow path has a shape extending toward the inflow opening in a posture inclined in the circumferential direction with respect to the central axis. A coil spring (68), which is housed in the valve chamber and is formed by spirally winding a linear material, is further provided.
The fuel injection device according to any one of claims 1 to 3, wherein the winding direction of the coil spring is along the flow direction of the swirling flow. The fuel injection device according to any one of claims 1 to 5, wherein the outflow axis (AL2) that defines the direction of the outflow opening passes through a position shifted to the outer peripheral side with respect to the central axis. The fuel injection device according to any one of claims 1 to 6, wherein the inflow opening and the outflow opening are provided on the same side with respect to a virtual vertical cross section (VP) of the valve body including the central axis. ..

Images