JP4134978B2 - Fuel injection device - Google Patents

Description

  The present invention relates to a fuel injection device.

  As a fuel injection device, for example, a fuel injection valve that directly or indirectly injects fuel into a combustion chamber of an internal combustion engine is known. The fuel supplied from the fuel injection valve is mixed with air in the intake pipe or the combustion chamber to form a combustible mixture in the combustion chamber. The combustible air-fuel mixture in the combustion chamber is compressed by piston motion, and then ignited and combusted by an ignition device, and is used as power for the internal combustion engine. As injection / spray characteristics of fuel injected from a fuel injection valve, there are an injection rate and a spray penetration (spray tip reach distance), and the injection rate and the spray penetration have an optimum state depending on the operating state of the internal combustion engine.

As a means for realizing this, Patent Document 1 discloses a technique for switching the spray shape to two stages. According to the prior art disclosed in Patent Document 1, the spray rate is switched to two stages by switching the lift amount of the nozzle needle, so that the optimum injection rate according to the operating state is considered. As means for switching the lift amount of the nozzle needle in two stages, a stopper solenoid different from the conventional injection solenoid is provided. By operating another solenoid, the axial position of the stopper that limits the lift amount of the nozzle needle is controlled. Specifically, the injection solenoid drives a movable core integrated with the nozzle needle. On the other hand, the solenoid for stopper drives the stopper to the side where the lift of the movable core is increased, that is, the side where the lift amount of the nozzle needle is increased. The stopper is provided with a second spring that urges the stopper toward the side where the lift becomes smaller, separately from the first spring that urges the movable core toward the side where the lift becomes smaller.
JP 2001-153003 A

  However, in the above prior art, the stopper solenoid is switched from the energized state to the non-energized when it is desired to reduce the needle lift during the period in which the injection solenoid is operated to repeat the fuel injection to each cylinder of the internal combustion engine. However, demagnetization is not promoted, and there is a possibility that the responsiveness of the movement in the stopper axial direction or the valve closing responsiveness may be lowered.

  Further, in the above prior art, since it is necessary to provide another solenoid in addition to the injection solenoid, there is a problem that the system is complicated and an increase in cost is unavoidable.

  The present invention has been made in view of such circumstances, and its purpose is to provide a fuel injection device that has a function of switching injection / spray characteristics such as an injection rate and can improve switching responsiveness. There is to do.

  In order to achieve the above object, the present invention comprises the following technical means.

That is, in the inventions according to claims 1 to 5, a nozzle body having a valve seat on the upstream side of the nozzle hole, a nozzle needle accommodated in the nozzle body so as to be movable in the axial direction, and separated and seated on the valve seat; A first movable core that cooperates with the nozzle needle, a second movable core that is opposed to the first movable core in the axial direction and is movable in the axial direction, and the first movable core and the second movable core in the seating direction of the nozzle needle A fuel injection device comprising a biasing member for biasing, wherein the lift amount of the nozzle needle is variable according to the axial position of the second movable core;
A drive coil capable of applying a magnetic force to the first movable core and the second movable core, and a permanent magnet capable of attracting and repelling the second movable core against the magnetic force on the first movable core side;
The urging member includes a first urging member that urges the first movable core and a second urging member that urges the second movable core. On the inner peripheral side of the second urging member, A first urging member and an urging force adjusting member that applies a load to the first urging member are provided.

  According to this, as a drive means of the second movable core for making the lift amount of the nozzle needle variable, it has a drive coil capable of applying a magnetic force to the first movable core and the second movable core, and a permanent magnet, The permanent magnet allows the second movable core to be attracted to the side opposite to the first movable core and repelled toward the first movable core according to the magnetic force of the drive coil. For example, the axial position of the second movable core is moved away from the first movable core, that is, away from the first movable core by utilizing the attraction and repulsion force of the permanent magnet with respect to the magnetic pole direction of the magnetic force. The position can be switched between the position on the direction side and the direction repelled toward the first movable core, that is, the position closer to the first movable core.

  Therefore, instead of switching the amount of lift of the nozzle needle by providing, for example, two solenoids, that is, two drive coils and stopping and energizing the stopper drive coil as in the prior art, the magnetic pole direction of the magnetic force generated in the drive coil is changed. By switching, it is possible to switch the lift amount of the nozzle needle. Further, since the attraction and repulsive force of the permanent magnet is used, the response of switching the lift amount can be improved compared to the conventional configuration in which the energization is stopped, that is, the demagnetization is performed and the lift amount is switched.

  In the case of the prior art in which the stopper drive coil is energized, that is, excited, the original electromagnetic force is not generated until the magnetic saturation occurs and the electromagnetic force is relatively small during the transition period until the magnetic saturation occurs. . For example, in order to efficiently convert the electromagnetic force into a flow of magnetic flux that magnetically attracts the second movable core, it is necessary to earn a facing area as a magnetic path area. However, when the first urging member and the second urging member are disposed inside, there is a risk of increasing the size of the physique. As a solution to this problem, a method of arranging the first urging member and the second urging member in series is conceivable, but it is difficult to adjust each urging force that urges the first movable core and the second movable core. There's a problem.

  On the other hand, since the permanent magnet can be magnetized and magnetized so as to always generate a saturation magnetic force, there is no need to increase the facing area as in the case of a conventional stopper driving coil. Therefore, the first urging member and the second urging member can be arranged in duplicate inside and outside, and the urging force can be applied independently to the first movable core and the second movable core. Can be easily adjusted, and the size of the physique can be prevented from increasing.

  An urging force adjusting member as an urging force adjusting means for adjusting the urging force of the first urging member and the first urging member that urges the first movable core is provided on the inner peripheral side of the second urging member. Is arranged.

  Further, the invention according to claim 2 is characterized in that the permanent magnet is disposed on the side of the second movable core opposite to the first movable core.

  According to this, when the magnetic pole of the second movable core is reversed by the action of the magnetic force of the drive coil, for example, the magnetic force biased to the magnetic force of the permanent magnet acts on the second movable core compared to before the magnetic pole is reversed. A magnetic force obtained by adding the magnetic force of the motor and the electromagnetic force of the drive coil acts, or an electromagnetic force repelling the permanent magnet acts. When the biased magnetic force acts, the second movable core is attracted to the permanent magnet side, that is, the axial position on the direction side far from the first movable core, and when the magnetic force repelling the permanent magnet acts, The movable core is pushed back to the axial position on the side closer to the first movable core. As a result, it becomes easy to change the displacement amount of the first movable core, that is, the lift amount of the nozzle needle by the displacement operation of the second movable core. Furthermore, it is possible to provide a function of changing the injection / spray characteristics such as the injection rate with a simplified configuration as compared with the conventional case.

  According to a third aspect of the present invention, a magnetic material is disposed between the second movable core and the permanent magnet.

  According to this, it is preferable that a magnetic body is disposed between the second movable core and the permanent magnet. For example, when the magnetic field (magnetic pole direction of the magnetic force) generated in the first movable core and the second movable core by the action of the magnetic force of the drive coil and the magnetic field of the permanent magnet are in opposite directions, the magnetic flux flow of the drive coil is It does not act directly on the permanent magnet itself that becomes a magnetic resistance against the flow of the magnetic flux, but acts on the magnetic body provided between the permanent magnet and the second movable core, thus mitigating or removing the influence of the magnetic flux of the permanent magnet. it can. Therefore, the electromagnetic force generated in the drive coil can be used efficiently.

  According to a fourth aspect of the present invention, the contact surface of the biasing force adjusting member with the first biasing member is substantially cylindrical.

  According to this, the first urging member and the second urging member are doubly arranged inside and outside, and the urging force can be adjusted so that the respective urging forces to the first movable core and the second movable core can be independently adjusted. An adjustment member can be arranged.

  The invention according to claim 5 is characterized by comprising switching means for switching the energization direction to the drive coil. Thereby, the polarity of a 1st movable core and a 2nd movable core can be reversed by switching the electricity supply direction to a drive coil.

  Hereinafter, the fuel injection device according to the present invention is applied to an apparatus that injects and supplies fuel to a gasoline engine, and a specific embodiment will be described with reference to the drawings.

  FIG. 1 is a partial cross-sectional view showing the configuration of the fuel injection device of the present embodiment. FIG. 2 is a schematic circuit diagram showing an electrical configuration according to the present embodiment. FIG. 3 is a diagram showing a switching operation of switching means for switching the energization direction to the electromagnetic coil in FIG. FIG. 4 is a schematic cross-sectional view showing the operating state of the fuel injection device of FIG. 1 and a partial cross-sectional view showing a non-energized state of the drive coil. FIG. 5 is a schematic cross-sectional view showing the operating state of the fuel injection device of FIG. FIG. 6 is a schematic cross-sectional view showing the operating state of the fuel injection device of FIG. 1, and is a partial cross-sectional view showing a reverse state of the energization direction to the drive coil. FIG. 7 is a graph showing the relationship between the injection amount of fuel injected from the fuel injection valve in FIG. 1 and the injection period, and FIG. 7A is a graph showing individual variations of the fuel injection valve. FIG. 7B is a graph showing the state after adjustment of the urging force of the first urging member by the urging force adjusting member of each fuel injection valve. In FIG. 1, the drive coil is in a non-energized state.

  The fuel injection device 1 is used for an internal combustion engine (engine), particularly a gasoline engine. As shown in FIG. 1, the fuel injection device 1 includes a fuel injection valve (referred to as an injector) 2 that injects fuel into a combustion chamber (not shown) of an engine, and control means (hereinafter referred to as an injection operation of the injector 2). , Referred to as an ECU) 100.

  More specifically, the injector 2 is attached to an intake pipe such as an intake port of a multi-cylinder (for example, 4-cylinder) gasoline engine (hereinafter referred to as an engine) or each cylinder, and injects fuel into a combustion chamber in the cylinder. To do. In this embodiment, it is assumed that the injector 2 is provided in each cylinder. The fuel pressurized by a fuel pump (not shown) is supplied to the injector 2 via a fuel distribution pipe (not shown). In general, fuel in a fuel tank (not shown) is sucked and discharged to a fuel distribution pipe by a fuel pump (not shown), and the discharged fuel is guided. The discharged fuel is regulated to a predetermined pressure by a pressure regulating device such as a pressure regulator (not shown) and sent to the fuel distribution pipe. When the engine is a direct injection engine, the pressure of the fuel supplied to the combustion chamber of the internal combustion engine is about 2 Mpa or more, and therefore, a predetermined low pressure (for example, 0.2 Mpa) sucked up from the fuel tank by the fuel pump. Is pressurized with a high-pressure pump (not shown), and the pressurized predetermined high-pressure fuel (for example, a predetermined fuel in the range of 2 to 13 MPa) is supplied to the injector 2 through the fuel distribution pipe. . The fuel discharged from the fuel pump and the fuel supplied from the high pressure pump to the fuel distribution pipe are regulated to a predetermined pressure by a pressure regulating device such as a pressure regulator (not shown). Hereinafter, the engine described in this embodiment is a gasoline direct injection engine.

  First, the injector 2 will be described with reference to FIG. The injector 2 has a substantially cylindrical shape, receives fuel from one end, and injects fuel from the other end via an internal fuel passage. The injector 2 includes a valve portion B that blocks and allows fuel injection, and an electromagnetic drive portion S that drives the valve portion B, and controls the fuel flowing into the internal fuel passage from the fuel introduction portion 48 side. The fuel is injected from part B into the engine cylinder.

  As shown in FIG. 1, the valve portion B includes a nozzle body 12 as a valve body, a nozzle needle 30 as a valve member, and a housing 16. The nozzle body 12 is fixed to the inner wall of the end portion of the fuel injection side of a housing (hereinafter referred to as a valve housing) 16 by welding. The nozzle body 12 has a conical surface 13 as an inner peripheral surface that decreases in diameter toward the nozzle hole 21 side in the fuel flow direction. The nozzle needle 30 can be separated from and seated on the conical surface 13. Here, the conical surface 13 constitutes a valve seat 14 on which the nozzle needle 30 can be separated and seated. Specifically, the contact portion 31 of the nozzle needle 30 is separated from and seated on the valve seat 14. The nozzle needle 30 is formed in a substantially shaft shape, and can reciprocate in the valve body 12 in the axial direction. Here, the valve seat 14 and the contact portion 31 constitute a seat portion that functions as an oil tight function for the valve portion to block fuel injection.

  As shown in FIG. 1, an injection hole 21 that can communicate with the internal fuel passage is disposed on the central side of the valve seat toward the downstream side of the fuel flow of the valve seat 14. The size of the nozzle hole 21, the direction of the nozzle hole axis, the nozzle hole arrangement, and the like are determined in accordance with the required fuel spray shape, direction, number, and the like. The opening area of the nozzle hole defines the flow rate when the valve is opened. The fuel injection amount of the injector 2 is measured by the opening area of the opened nozzle hole, the lift amount of the nozzle needle 30 and the valve opening period. When the nozzle needle 30 is seated on the valve seat 14, fuel injection from the nozzle hole 21 is cut off, and when the nozzle needle 30 is separated from the valve seat 14, fuel injection from the nozzle hole 21 is allowed and fuel is injected.

  The lift amount that affects the fuel injection amount described above is an increase in the lift amount in the relationship of lift amount-opening area by the nozzle needle 30 (specifically, the contact portion 31 and the nozzle body 12 (specifically, the valve seat 14)). Accordingly, the separation distance between the seal portions 31 and 14 increases, so that the fuel injection amount increases while the opening area by the seal portion is smaller than the opening area by the injection hole (for example, the lift amount H = HD1, which will be described later). .

  The valve housing 16 includes a valve housing lower portion 16a that fixes the nozzle body 12, and a valve valve housing upper portion 16b that is fixed to the cylindrical member 15 on the electromagnetic drive unit S side. It is inserted and fixed to the inner periphery 16ba of the housing upper part 16b. The valve housing lower portion 16a and the valve housing upper portion 16b are not limited to a configuration in which separate members that can be inserted and fixed are assembled and fixed integrally, but may be formed integrally.

  As shown in FIG. 1, the electromagnetic drive unit S includes a first movable core 50, a second movable core 60 that faces the first movable core 50 in the axial direction, a coil 70, a permanent magnet 80, and the first movable core 50. And urging members 59 and 69 as urging means for urging the second movable core 60. The first movable core 50 is a stepped substantially cylindrical body made of a magnetic material such as magnetic stainless steel. The first movable core 50 is fixed to the nozzle needle 30, and the first movable core 50 and the nozzle needle 30 cooperate with each other. Note that the first movable core 50 and the nozzle needle 30 are not limited to those in which separate members are integrally formed by welding or the like as shown in FIG. 1, but may be formed integrally.

  The second movable core 60 is a substantially cylindrical body made of a magnetic material such as magnetic stainless steel. The second movable core 60 is movable in the axial direction on the inner periphery of the cylindrical members 15 and 18. Specifically, the second movable core 60 is accommodated in the inner circumferences 15a and 15b of the cylindrical member 15 so as to be movable in the axial direction. The cylindrical member 15 is formed of a pipe material made of a magnetic material or the like, and has a step portion 15k made of stepped inner peripheries 15a and 15b. The stepped portion 15k restricts the movement of the second movable core 60 in the axial direction (specifically, the downward movement in the axial direction). More specifically, the cylindrical member 15 has an inner circumference 15b larger than the inner circumference 15a. The outer periphery on the lower end side of the second movable core 60 is held movably on the inner periphery 15a. Further, the annular portion 62 formed on the outer periphery on the upper end side of the core 60 is movably held on the inner periphery 15b, and the downward movement in the axial direction of the annular portion 62 is locked to the step portion 15k. It is restricted when it is done.

  The coil 70 is wound around the outer periphery of a resin spool (not shown) in a predetermined direction. The ends of the coil 70 are drawn out as two terminals (not shown). The terminal supplies current to the coil 70 from an external power source or the like (specifically, the ECU 100). The spool is mounted on the outer periphery of the cylindrical members 15 and 18. Here, the coil 70, the spool, and the terminal constitute a drive coil. In addition, the resin mold 19 is arrange | positioned in the outer peripheral side of drive coils, such as the coil 70, and the connector part (not shown) which accommodates a terminal is provided.

  The permanent magnet 80 is a magnetized magnetic material such as a ferrite magnet, a rare earth magnet, or an alnico magnet. As shown in FIG. 1, the permanent magnet 80 is formed in a substantially cylindrical body and is magnetized so as to generate a predetermined magnetic force. The permanent magnet 80 is disposed on the side of the second movable core 60 opposite to the first movable core 50 so as to face the second movable core 60 in the axial direction.

  As shown in FIG. 4, the magnetic pole of the permanent magnet 80 is not limited to the magnetic pole arrangement in which the end surface on the second movable core 60 side is the S pole and the end surface on the anti-second movable core 60 side is the N pole. The magnetic pole arrangement may be such that the end surface on the 60 side is the N pole and the end surface on the anti-second movable core 60 side is the S pole. The end face on the second movable core 60 side is the N pole, and the end face on the second movable core 60 side is the N pole instead of the former in which the end face on the second movable core 60 side is the S pole and the end face on the anti-second movable core 60 side is the N pole. 2 In the latter configuration in which the magnetic pole is disposed with the end surface on the movable core 60 side as the S pole, the ECU 100 in the latter is used so that the relationship between the magnetic force by the permanent magnet 80 and the electromagnetic force by the drive coil is the same as the former. The energization direction to the drive coil is reversed.

  In the magnetic pole arrangement of the permanent magnet 80 described in the following embodiment, the end face on the second movable core 60 side is the S pole, and the end face on the anti-second movable core 60 side is the N pole (see FIG. 4).

  As shown in FIG. 1, the urging members 59 and 69 include a first urging member (hereinafter referred to as a first spring) 59 that urges the first movable core 50 in the seating direction of the nozzle needle 30, and a second The movable core 60 is composed of a second urging member (hereinafter referred to as a second spring) that urges the movable core 60 in the seating direction of the nozzle needle 30. The first spring 59 and the second spring 69 may be any member as long as it is an elastic body such as a spring member that is displaced according to the applied load. In this embodiment, the first spring 59 and the second spring 69 are spring members.

  The first spring 59 is engaged with a first movable core (specifically, a spring seat 50 s in the first movable core 50 at one end and an urging force adjusting member (hereinafter referred to as an adjusting pipe) 41 at the other end. Specifically, the adjusting pipe 41 is press-fitted into the inner periphery 48a of the fuel introduction portion 48 to form a fuel passage therein, and by adjusting the amount of press-fitting of the adjusting pipe 41, The urging force (load) of the first spring 59 urging the first movable core 50 is changed, and the urging force of the first spring 59 urges the first movable core 50 and the nozzle needle 30 toward the valve seat 14. Has been.

  The second spring 69 is sandwiched between the second movable core 60 and a member opposed to the second movable core 60 such as the magnetic body 17 in the axial direction at the other end. Specifically, the second spring 69 can be inserted through the inner periphery of the magnetic body 17 and the permanent magnet 80, one end is locked to the upper end surface of the second movable core 60, and the other end is in the fuel introduction portion 48. It is locked to the spring seat surface.

  As shown in FIG. 1, a first spring 59 and an adjusting pipe 41 are arranged on the inner peripheral side of the second spring 69. The second spring 69 and the first spring 59 constitute an urging means that is double-arranged inside and outside.

  In this embodiment, it is preferable that the adjusting pipe 41 is a substantially cylindrical body, and the contact surface of the adjusting pipe 41 with the first spring 59 is cylindrical. Thereby, the adjusting pipe is arranged so that the second spring 69 and the first spring 59 are doubly arranged inside and outside, and each urging force to the first movable core 50 and the second movable core 60 can be adjusted independently. 41 can be arranged.

  In the present embodiment, it is preferable to provide the magnetic body 17 between the second movable core 60 and the permanent magnet 80 as shown in FIG. The magnetic body 19 is not magnetized by magnetization like a ferromagnetic material such as a permanent magnet, but uses a magnetic material such as a soft magnetic material that is relatively easily magnetized and has little residual magnetism. For example, depending on the energization direction to the drive coil, the magnetic field generated in the first movable core 50 and the second movable core 60 (magnetic pole direction of the magnetic force) and the magnetic field of the permanent magnet 80 may be opposite to each other. In this case, by providing the magnetic body 17, the flow of the magnetic flux of the drive coil does not directly act on the permanent magnet 80 itself that becomes a magnetic resistance against the flow of the magnetic flux, and the permanent magnet 80 and the second movable core. 60 acts on the magnetic body 17 provided between 60. Therefore, since the influence of the magnetic flux of the permanent magnet 80 can be reduced or eliminated, the electromagnetic force generated in the drive coil can be used efficiently.

  When the above-described magnetic body 17 is disposed between the permanent magnet 80 and the core 60, the magnetic body 17 is arranged in the direction toward the permanent magnet 80 of the second movable core 60 in place of the permanent magnet 80 magnetized by magnetization. It has a function of regulating the amount of movement (in the axial direction upward in FIG. 1). Note that the lower end surface 17 a of the magnetic body 17 is not limited to a substantially planar shape that substantially contacts the second movable core 60, but a substantially annular step (not shown) so as to contact a part of the second movable core 60. A stepped flat surface having In the configuration in which the step is provided in the shape of the lower end surface 17 a of the magnetic body 17, even if the second movable core 60 is once coupled by the magnetic force of the magnetic body 17, When the magnetism is reversed, the second movable core 60 is released from the magnetic body 17 and is easily detached.

  As shown in FIG. 1, the magnetic body 17 is formed in a bottomed cylindrical shape so as to accommodate and hold the permanent magnet 80. The magnetic body 17 can be inserted and fixed to the inner periphery of the cylindrical member 18. In addition, the magnetic body 17 and the permanent magnet 80 are not limited to the configuration that allows the magnetic body 17 in which the permanent magnet 80 is accommodated to be inserted into the inner periphery of the cylindrical member 18, but the permanent magnet 80 and the magnetic body 17 are individually cylindrical. It may be inserted into the inner periphery of the member 18.

  The cylindrical members 15 and 18 are connected to the cylindrical member 18 that houses the permanent magnet 80 and the magnetic body 17 therein, and the cylindrical member 15 that can move the second movable core 60 in the axial direction and restrict downward movement. ing. Note that the cylindrical members 15 and 18 are not limited to being formed as separate members and are integrally connected, but may be integrally formed.

  As shown in FIG. 1, the internal fuel passage of the injector 2 includes an inner circumference 48 a of the fuel introduction portion 48, an inner circumference of the adjusting pipe 41, and a permanent magnet 80 from the upstream side to the downstream side of the fuel flow. The inner periphery of the magnetic body 17, the inner periphery 61 of the second movable core 60, the radial passage 52 of the first movable core 50, the inner periphery of the valve housings 16a and 16b, and the inner periphery of the nozzle body 12. A fuel passage formed by the circumference and the nozzle needle 30 is formed in this order, and these constitute an internal fuel passage as a fuel flow path toward the nozzle hole 21.

  The ECU 100 is configured as a microcomputer having a known configuration in which a read only memory (ROM), a random access memory (RAM), a microprocessor (CPU), an input port, and an output port (not shown) are connected to each other via a bidirectional bus. Yes. The ECU 100 controls the energization period of the injector 2 by starting and stopping energization of the coil 70 of the injector 2 using a power source such as a battery. The signals of various sensors (not shown) for detecting the operating state of the engine, such as the engine speed, intake pipe pressure (or intake air amount), cooling water temperature, etc., are read, and the injector 2 is operated according to various programs (not shown) for the engine. The operation of the electromagnetic drive unit S is controlled (see FIG. 1).

  The electrical configuration of the fuel injection device 1 of the present embodiment will be described with reference to FIGS. The ECU 100 supplies current in a predetermined direction to two terminals of the injector 2 (specifically, a drive coil) based on signals from various sensors that detect the operating state of the engine. As shown in FIG. 2, the ECU 100 includes a control unit 100a and an energization direction switching circuit 100b. Since the control unit 100a is the microcomputer described above, description thereof is omitted.

  The energization direction switching circuit 100b has a configuration in which an H bridge circuit is assembled by four switching elements (hereinafter referred to as transistors) TR1, TR2, TR3, and TR4 with a driving coil (specifically, a coil 70) of the injector 2 as a center. ing. One end of the coil 70 wound in a predetermined direction is connected to an intermediate point between the first transistor TR1 on the battery power supply voltage Vb side and the second transistor TR1 on the ground side, which are connected in series. The other end side of the coil 70 is connected in series to an intermediate point between the third transistor TR3 on the battery power supply voltage Vb side and the fourth transistor TR4 on the ground side. In the energization direction switching circuit 100b, as shown in FIG. 3, by turning on only energization to the base terminal of the first transistor TR1 and the base terminal of the fourth transistor TR4, the direction of the current flowing to the coil 70 is changed. It becomes a predetermined direction. Further, by turning ON only the power supply to the base terminal of the second transistor TR2 and the base terminal of the third transistor TR3, the direction of the current flowing through the coil 70 is reversed from the predetermined direction and becomes the anti-predetermined direction. . In the following description of the present embodiment, the predetermined current direction is referred to as a forward direction, and the anti-predetermined current direction is referred to as a reverse direction.

  Here, ECU 100 has switching means for switching the energization direction to the drive coil of injector 2 as one of means for controlling the system. This switching means switches the direction of current flowing through the coil 70 from the normal direction to the reverse direction, or from the reverse direction to the normal direction by switching the energization direction.

  The operation of the fuel injection device 1 having the above-described configuration, particularly the operation of the injector 2 will be described below with reference to FIGS. 4 to 6, the direction of the current of the battery power supply or the like supplied from the ECU 100 to the drive coil (specifically, the coil 70) is schematically represented by the direction of the battery for convenience. First, the non-energized state of the drive coil (see FIG. 4), the energized direction of the drive coil in the forward direction (see FIG. 5), and the energized direction of the drive coil in the reverse direction (see FIG. 6) will be described. . 4 to 6, the arrow direction indicates the direction of the magnetic field (magnetic flux flow).

  (1) When the drive coil (specifically, the coil 70) shown in FIG. 4 is not energized, the magnetic flux of the permanent magnet 80 forms a closed circuit through the magnetic body 17. Since the magnetic force of the permanent magnet 80 does not reach the second movable core 60 through the magnetic body 17, no attractive force that attracts the second movable core 60 to the permanent magnet 80 is generated. On the other hand, since the drive coil is in a non-energized state, no electromagnetic force is generated in the coil 70, and the nozzle needle 30 is pressed against the valve seat 14 by the first spring 59. As a result, the injector 2 is closed and fuel is not injected from the injection hole 21.

  Since the second movable core 60 is biased toward the step portion 15k of the cylindrical member 15 by the biasing force of the second spring 69, the second movable core 60 is locked to the step portion 15k by this biasing force. ing. For this reason, the movement position of the second movable core 60 is restricted to the lower limit position of the axial movement (hereinafter referred to as a position restricted to a low lift state).

  (2) When the energization direction to the drive coil shown in FIG. 5 is in the positive direction, the coil 70 is energized, and an electromagnetic force is generated in the coil 70. Further, since the energization direction to the drive coil is set to the positive direction, the magnetic pole on the end surface of the second movable core 60 on the permanent magnet 80 side becomes the S pole, and the magnetic pole on the end surface of the permanent magnet 80 on the second movable core 23 side. It becomes a repulsive relationship with the S pole. As a result, the 2nd movable core 60 is maintained in the position restrict | limited to a low lift state.

  On the other hand, the second movable core 60 magnetized by the coil 70 attracts the first movable core 50, and the nozzle needle 30 cooperating with the first movable core 50 is separated from the valve seat 14. At this time, since the axial displacement of the movable core 50 is restricted by the position where the second movable core 60 is restricted to the low lift state, the lift amount H of the nozzle needle 30 is restricted to the low lift state (H = HD1). ).

  At this time, the electromagnetic force of the coil 70 repelling against the magnetic force (hereinafter referred to as steady magnetic force) by the permanent magnet 80 is acting on the second movable core 60. As shown in FIG. 5, the electromagnetic force of the coil 70, that is, the flow of magnetic flux, does not directly act on the permanent magnet 80 itself but acts on the magnetic body 17. As a result, the flow of magnetic flux in the coil 70 is not hindered by the flow of magnetic flux in the permanent magnet 80 that becomes a magnetic resistance to the flow of magnetic flux. Therefore, compared to the injector having a configuration in which the permanent magnet 80 and the second movable core 60 are directly opposed in the axial direction without arranging the magnetic body 17 between the permanent magnet 80 and the second movable core 60, Even when the generated electromagnetic force is reduced to about half, it is possible to obtain an operating force equal to or higher than that.

  Here, the magnetic circuit formed by the magnetic force of the permanent magnet 80 and the magnetic circuit formed by the electromagnetic force of the coil 70 are respectively transmitted through the magnetic body 17 sandwiched between the permanent magnet 80 and the second movable core 60. A closed circuit is formed.

  (3) In the state where the energization direction to the drive coil shown in FIG. 6 is in the reverse direction, the energization direction to the drive coil can be switched from the normal direction to the reverse direction, so the direction of the magnetic field due to the electromagnetic force generated in the coil 70 is The direction of the magnetic field always generated in the permanent magnet 80 is the same. At this time, a magnetic force biased by the electromagnetic force of the coil 70 acts on the second movable core 60 in addition to the steady magnetic force of the permanent magnet 80. As a result, the second movable core 60 is attracted to the magnetic body 17 side and is locked to the lower end surface 17 a of the magnetic body 17. For this reason, the movement position of the second movable core 60 is restricted to the upper limit position of the axial movement (hereinafter referred to as a position restricted to a high lift state). 5 and 6 indicate the direction of the magnetic field, that is, the lines of magnetic force. In FIG. 6, the magnetic field lines due to the electromagnetic force of the coil 70 and the magnetic field lines due to the magnetic force of the permanent magnet 80 are shown separately for convenience (each magnetic field line indicated by a solid line in FIG. 6), but the magnetic force of these magnetic field lines is biased. The magnetic field lines of the coil 70 and the permanent magnet 80 become one large magnetic field line (the magnetic field line indicated by a one-dot chain line in FIG. 6).

  On the other hand, the second movable core 60 magnetized by the coil 70 and the permanent magnet 80 attracts the first movable core 50 and makes the lift amount H of the nozzle needle 30 high (H = HD2, where HD2> HD1). ).

  Next, the overall operation of the fuel injection device 1 will be described. ECU 100 detects the operating state of the engine from signals from various sensors. Then, the ECU 100 determines the injection / spray characteristics such as the injection rate and the spray shape for fuel injection from the injection hole 21 suitable for the operating state based on the detected operating state of the engine. When the ECU 100 determines that the injection / spray characteristic suitable for the operating state is to set the lift amount of the nozzle needle 30 to the low lift state, the ECU 100 determines the first and fourth of the energization direction switching circuit 100b. The transistors TR1 and TR4 are turned on, and the energization direction to the drive coil is set to the positive direction. As a result, the movement position of the second movable core 60 is restricted to a position where the second movable core 60 is restricted to the low lift state, only the first needle 31 is opened, and the lift amount H of the nozzle needle 30 is controlled to H = HD1. On the other hand, when the ECU 100 determines that the injection / spray characteristics suitable for the operating state are those that bring the lift amount of the nozzle needle 30 to the high lift state, the ECU 100 determines that the second and second energization direction switching circuits 100b are the second and second. 3 transistors TR2 and TR3 are turned on, and the energization direction to the drive coil is reversed. As a result, the movement position of the second movable core 60 is restricted to a position where the second movable core 60 is restricted to the high lift state, and the lift amount H is controlled to H = HD2.

  Note that, by changing the lift amount, for example, the opening area for fuel injection changes, so the injection amount per unit time can be changed. As a result, the injection amount injected from the injector 2 is adjusted by adjusting the energization period to the coil 70. Furthermore, even if the energization period to the coil 70 is the same, the injection amount can be changed by setting the lift amount H to either H = HD1 or H = HD2.

  In this way, the polarity (magnetic pole) of the second movable core 60 can be reversed by switching the energization direction to the drive coil by the ECU 100 (specifically, the energization direction switching circuit 100b). When the polarity of the second movable core 60 is reversed, either the stationary magnetic force of the permanent magnet 80 and the magnetic force biased by the electromagnetic force of the coil 70 or the electromagnetic force of the coil 70 repelling the stationary magnetic force of the permanent magnet 80 is the second. It acts on the movable core 60. When a biased magnetic force acts on the second movable core 60, the upper limit position is attracted to the permanent magnet 80 side (specifically, the lower end surface 17 a of the magnetic body 17) and can move upward in the axial direction of the second movable core 60. It is restricted to (position limited to a high lift state). On the other hand, when the electromagnetic force of the coil 70 repelling the permanent magnet 80 acts on the second movable core 60, the second movable core 60 is pressed toward the anti-permanent magnet 80, that is, in the direction of the valve seat 14, and the second movable core. 60 is regulated to a lower limit position (position limited to a low lift state) that can move downward in the axial direction. Note that the electromagnetic force of the drive coil can act on the first movable core 50 and the second movable core 60. In both the low lift state (see FIG. 5) and the high lift state (see FIG. 6), the coil 70 is energized and an electromagnetic force is generated in the coil 70. The first movable core 50 is attracted by this electromagnetic force.

  Here, the second movable core 60, the permanent magnet 80, and the energization direction switching circuit 100b constitute lift variable means for making the lift amount of the nozzle needle 30 variable. By the displacement operation of the second movable core 60, the displacement amount of the first movable core 50, that is, the lift amount H of the nozzle needle 30 can be changed from HD2 to HD1 or from HD1 to HD2. By the lift variable means 60, 80, 100b, the lift amount of the injector 2 is switched between the low lift state (H = HD1) and the high lift state (H = HD2).

  In the fuel injection device described above, even if the configuration and operation of the injector 2 are the same, for example, the following variations may occur in the individual injectors 2 during the manufacturing process. As shown in FIG. 7A, even when the same injection period Ti, that is, the energization period to the drive coil is the same, the fuel injection amounts of the individual injectors 2 are different. In FIG. 7A, the horizontal axis represents the injection period Ti and the vertical axis represents the fuel injection amount q. For convenience, the number of injectors 2 shown in FIG. 7A is three. The injector 2 in the middle of the manufacturing process adjusts the valve opening response of the nozzle needle 30 and the like, so that the first movable core 50 and the nozzle needle 30 are urged toward the valve seat 14 by the first spring 59 ( It is necessary to adjust the load.

  On the other hand, in the present embodiment, the first spring 59 and the second spring 69 are arranged double inside and outside, and an urging force applied to the first movable core 50 (hereinafter referred to as a first urging force), a second The urging force applied to the movable core 60 (hereinafter referred to as the second urging force) can be adjusted independently. The first urging force is adjusted to a predetermined urging force (load) by adjusting the press-fitting amount of the adjusting pipe 41. As a result, the fuel injection amounts of the individual injectors 2 can be adjusted to be the same (see FIG. 7B). Therefore, it is possible to align the injection characteristics of the individual injectors 2 with respect to the injection period to the characteristics required for the injector applied to the engine by adjusting the first urging force.

  Next, functions and effects of the present embodiment will be described. (1) In the present embodiment, the first movable core 60 that cooperates with the nozzle needle 30 and the first movable core 50 face each other in the axial direction and can move in the axial direction. In the injector that has a variable second movable core and makes the lift amount of the nozzle needle 30 variable, the first movable as drive means for driving the second movable core 60 for making the lift amount of the nozzle needle 30 variable A drive coil (specifically, coil 70) capable of applying a magnetic force to the core 50 and the second movable core 60, and a permanent magnet 80, and the permanent magnet 80 causes the second movable core 60 to move according to the magnetic force of the drive coil. In addition, suction is possible on the side opposite to the first movable core 50 and repulsion is possible on the first movable core 50 side. By utilizing the attraction and repulsion force of the permanent magnet 80 with respect to the magnetic pole direction of the magnetic force, the axial position of the second movable core 60 is the direction attracted toward the anti-first movable core, that is, the first movable core 50. The position is controlled to a high lift state as a position on the direction far from the position, and a position to be repelled to the first movable core side, that is, a position to be controlled to a low lift state as a position on the direction side approaching the first movable core. be able to.

  Accordingly, instead of switching the amount of lift of the nozzle needle by providing two solenoids, that is, two drive coils as in the prior art and stopping and energizing the stopper drive coil, the magnetic pole direction of the magnetic force generated in the drive coil 70 is changed. It is possible to switch the lift amount of the nozzle needle 30 by switching. Further, since the attraction and repulsive force of the permanent magnet 80 is used, the responsiveness of the lift amount switching can be improved as compared with the conventional configuration in which the energization is stopped, that is, the demagnetization is performed and the lift amount is switched.

  (2) In the case of the conventional technology in which the stopper drive coil is energized, that is, excited, the original electromagnetic force is not generated until the magnetic coil is excited and magnetically saturated. Relatively small. In order to efficiently convert the electromagnetic force into a flow of magnetic flux that magnetically attracts the second movable core 60, it is necessary to earn a facing area as a magnetic path area. However, when the 1st spring 59 and the 2nd spring 69 are arrange | positioned inside, there exists a possibility of causing the enlargement of a physique. As a solution to this problem, a method of arranging the first spring and the second spring in series is conceivable. However, it is difficult to independently adjust the urging forces urging the first movable core 50 and the second movable core 60. There is a problem.

  On the other hand, in the present embodiment, the permanent magnet 80 can always be magnetized and magnetized so as to generate a saturation magnetic force, so that the facing area 17a is the same as the facing area in the case of a conventional stopper driving coil. There is no need to earn. Therefore, the first spring 59 and the second spring 60 can be arranged in duplicate inside and outside, and an urging force can be applied to the first movable core 50 and the second movable core 60 independently. Therefore, adjustment of each urging force is facilitated, and an increase in the size of the physique can be prevented.

  (3) An adjusting pipe as an urging force adjusting means for adjusting the urging force of the first spring 59 and the first spring 59 urging the first movable core 50 is provided on the inner peripheral side of the second spring 69. 41 is arranged.

  In general, even if the configuration and operation of the injector 2 are the same, for example, the injection characteristics such as the injection period Ti-injection amount characteristic of the individual injectors 2 during the manufacturing process may be different. In order to apply to an engine, it is necessary to align the individual injection characteristics of the injector 2.

  On the other hand, in the present embodiment, the first spring 59 and the second spring 69 are arranged double inside and outside, and the first biasing force applied to the first movable core 50 and the second bias applied to the second movable core 60. The biasing force can be adjusted independently. The first urging force is adjusted to a predetermined urging force (load) by adjusting the press-fitting amount of the adjusting pipe 41. As a result, the fuel injection amount of each injector 2 can be adjusted to be the same in the same injection period Ti. Therefore, it is possible to align the injection characteristics of the individual injectors 2 with respect to the injection period to the characteristics required for the injector applied to the engine by adjusting the first urging force.

  (4) Furthermore, in the present embodiment, the permanent magnet 80 is disposed on the side of the second movable core 60 opposite to the first movable core 50. Therefore, when the magnetic pole of the second movable core 60 is reversed by the action of the magnetic force of the drive coil, the magnetic force biased to the magnetic force of the permanent magnet 80 acts on the second movable core 60 as compared with that before the magnetic pole is reversed. Either a magnetic force obtained by adding the magnetic force of 80 and the electromagnetic force of the drive coil acts, or an electromagnetic force repelling the permanent magnet 80 acts. When a biased magnetic force acts, the second movable core 60 is attracted to an axial position far from the first movable core 50, that is, a position that is regulated to a high lift state, and a magnetic force repelling the permanent magnet 80 acts. In this case, the second movable core 60 is pushed back to the axial position on the side closer to the first movable core, that is, the position where the second movable core 60 is restricted to the low lift state. As a result, it becomes easy to change the displacement amount of the first movable core 50, that is, the lift amount of the nozzle needle 30 by the displacement operation of the second movable core 60. Furthermore, it is possible to provide a function of changing the injection / spray characteristics such as the injection rate with a simplified configuration as compared with the conventional case.

  (5) Furthermore, in this embodiment, it is preferable that the magnetic body 17 is disposed between the second movable core 60 and the permanent magnet 80. When the magnetic field (direction of magnetic force) generated in the first movable core 50 and the second movable core 60 and the magnetic field of the permanent magnet 80 are opposite to each other when the drive coil is energized (specifically, the energization direction is a positive direction). The magnetic flux flow of the drive coil does not directly act on the permanent magnet 80 itself, which becomes a magnetic resistance to the magnetic flux flow, but acts on the magnetic body 17. Can be removed. Therefore, the electromagnetic force generated in the drive coil can be used efficiently.

  (6) Furthermore, in the present embodiment, the contact surface of the adjusting pipe 41 with the first spring 59 is preferably cylindrical. Thereby, the adjusting pipe is arranged so that the second spring 69 and the first spring 59 are doubly arranged inside and outside, and each urging force to the first movable core 50 and the second movable core 60 can be adjusted independently. 41 can be arranged.

(Other embodiments)
In addition, although this embodiment demonstrated above demonstrated the structure by which the nozzle hole 21 is arrange | positioned in the downstream of the valve seat 14 of the nozzle body 12, even if it has the nozzle body 12 and an nozzle hole plate. Good. In this case, the nozzle hole plate is formed in a substantially bottomed cylindrical shape, and is sandwiched, for example, between the bottom of the valve housing 16 and the bottom of the valve body 12. A plurality of nozzle holes 21 are arranged in the nozzle hole plate. The nozzle plate constitutes a fuel spray forming means for atomizing the fuel and forming a spray.

It is a fragmentary sectional view showing the composition of the fuel injection device of the embodiment of the present invention. It is a typical circuit diagram which shows the electrical structure concerning this embodiment. It is a figure showing the switching operation | movement of the switching means which switches the electricity supply direction to the electromagnetic coil in FIG. It is typical sectional drawing which shows the operation state of the fuel-injection apparatus of FIG. 1, Comprising: It is a fragmentary sectional view which shows the non-energized state of a drive coil. It is a typical sectional view showing the operation state of the fuel injection device of Drawing 1, and is a fragmentary sectional view showing the forward direction state of the energization direction to a drive coil. It is a typical sectional view showing the operation state of the fuel injection device of Drawing 1, and is a fragmentary sectional view showing the reverse direction state of the energization direction to a drive coil. 7 is a graph showing the relationship between the injection amount of fuel injected from the fuel injection valve in FIG. 1 and the injection period, FIG. 7A is a graph showing individual variations of the fuel injection valve, FIG. These are graphs after adjusting the urging force of the first urging member by the urging force adjusting member of each fuel injection valve.

Explanation of symbols

1 Fuel injector 2 Injector (fuel injection valve)
12 Nozzle body (valve body)
14 Valve seat 15 Tube member 15a, 15b Inner circumference 15k Stepped part 21 Injection hole 30 Nozzle needle (valve member)
31 Contact part 50 1st movable core 60 2nd movable core 62 Annular part 70 Coil (a part of drive coil)
80 Permanent magnet 100 ECU (control means)
100a Control unit 100b Energizing direction switching circuit B Valve unit S Electromagnetic drive unit

Claims (5)

A nozzle body having a valve seat upstream of the nozzle hole;
A nozzle needle which is accommodated in the nozzle body so as to be axially movable, and which is separated from and seated on the valve seat;
A first movable core cooperating with the nozzle needle;
A second movable core that faces the first movable core in the axial direction and is movable in the axial direction;
A biasing member that biases the first movable core and the second movable core in a seating direction of the nozzle needle;
In the fuel injection device that makes the lift amount of the nozzle needle variable according to the axial position of the second movable core,
A drive coil capable of applying a magnetic force to the first movable core and the second movable core;
Providing a permanent magnet capable of attracting and repelling the second movable core on the side opposite to the first movable core with respect to the magnetic force;
The biasing member includes a first biasing member that biases the first movable core and a second biasing member that biases the second movable core, and an inner periphery of the second biasing member. The fuel injection device according to claim 1, further comprising: an urging force adjusting member that applies a predetermined load to the first urging member and the first urging member. 2. The fuel injection device according to claim 1, wherein the permanent magnet is disposed on a side opposite to the first movable core of the second movable core. The fuel injection device according to claim 1, wherein a magnetic body is disposed between the second movable core and the permanent magnet. The fuel injection device according to any one of claims 1 to 3, wherein a contact surface of the urging force adjusting member with the first urging member is substantially cylindrical. The fuel injection device according to any one of claims 1 to 4, further comprising switching means for switching an energization direction to the drive coil.

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