Fuel injection valve and method for driving a fuel injection valve

Abstract

To provide a fuel injection valve capable of suppressing heat generation amount and a method for operating the fuel injection valve.SOLUTION: A fuel injection valve includes: a body part having an inflow port to which fuel supplied from a fuel supply source flows in, a flow passage in which fuel flowing in from the inflow port flows and a discharge port connected to the flow passage to discharge the fuel; a valve unit that is at least partially formed by using a magnetic body, is disposed so as to be movable linearly between a position of closing the discharge port and a position of opening the discharge port and is energized in the direction of opening the discharge port by using pressure of the fuel flowing in from the inflow port and to which elastic force is applied in the direction of closing the discharge port by an elastic member; a solenoid device that has a coil, generates electromagnetic force by causing a drive current to flow in the coil and drives the valve unit in the direction of opening the discharge port by using the electromagnetic force; and a control section variably setting a value of the drive current to be caused to flow in the coil for a predetermined period including a supply start time of the drive current, in accordance with supply pressure of the fuel to be supplied to the inflow port.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a fuel injection valve and a method for driving the fuel injection valve.

Background Art

[0002] A common rail type fuel injection device applied to a diesel engine or the like includes a fuel pump, a common rail, and a fuel injection valve. The fuel pump sucks and pressurizes the fuel in the fuel tank and supplies it to the common rail as high-pressure fuel. The common rail holds the high-pressure fuel supplied from the fuel pump at a predetermined pressure. The fuel injection valve injects the high-pressure fuel in the common rail into the combustion chamber of the diesel engine by opening and closing the injection valve.

[0003] The fuel injection valve has a solenoid device that generates an electromagnetic force by passing an electric current through a coil wound around a core, and a valve unit formed using a magnetic material. In such a solenoid valve, for example, an elastic force is applied to the valve unit to hold down the fuel flow path, and when the solenoid device does not generate an electromagnetic force, the fuel flow path is held down by the elastic force and closed. When the solenoid device generates an electromagnetic force, the valve unit is attracted to the core side of the solenoid device by the electromagnetic force, and the flow path is opened by separating the valve unit from the flow path (see, for example, Patent Document 1, etc.).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the solenoid valve as described above, in order to generate a large electromagnetic force, it is necessary to increase the drive current flowing through the coil. When a high-value drive current is passed through the coil, the amount of heat generated in the coil increases, and the heat load in the solenoid becomes high. For this reason, in a solenoid device that needs to generate a large electromagnetic force, it is necessary to separately provide a cooling mechanism for cooling the coil.

[0006] The present disclosure has been made in view of the above, and an object thereof is to provide a fuel injection valve capable of suppressing the amount of heat generation and a method for driving the fuel injection valve.

Means for Solving the Problems

[0007] The fuel injection valve according to the present disclosure includes a main body portion having an inlet through which fuel supplied from a fuel supply source flows in, a flow path through which the fuel flowing in from the inlet flows, and an outlet connected to the flow path for discharging the fuel, and at least a part of which is formed using a magnetic material, and is arranged to be linearly movable between a position closing the outlet and a position opening the outlet, and is biased in a direction to open the outlet by the pressure of the fuel flowing in from the inlet, and a valve unit to which an elastic force is applied in a direction to close the outlet by an elastic member, a solenoid device having a coil, generating an electromagnetic force by passing a drive current through the coil, and driving the valve unit in a direction to open the outlet by the electromagnetic force, and a control unit configured to variably set a value of the drive current flowing through the coil during a predetermined period including a start point of supply of the drive current according to the supply pressure of the fuel supplied to the inlet. to The fuel injection valve according to the present disclosure includes a main body portion having an inlet through which fuel supplied from a fuel supply source flows in, a flow path through which the fuel flowing in from the inlet flows, and an outlet connected to the flow path for discharging the fuel, and at least a part of which is formed using a magnetic material, and is arranged to be linearly movable between a position closing the outlet and a position opening the outlet, and is biased in a direction to open the outlet by the pressure of the fuel flowing in from the inlet, and a valve unit to which an elastic force is applied in a direction to close the outlet by an elastic member, a solenoid device having a coil, generating an electromagnetic force by passing a drive current through the coil, and driving the valve unit in a direction to open the outlet by the electromagnetic force, and a control unit configured to variably set a value of the drive current flowing through the coil during a predetermined period including a start point of supply of the drive current according to the supply pressure of the fuel supplied to the inlet.

[0008] The method for driving a fuel injection valve according to the present disclosure includes a main body portion having an inlet through which fuel supplied from a fuel supply source flows in, a flow path through which the fuel flowing in from the inlet circulates, and an outlet connected to the flow path for discharging the fuel; a valve unit at least partially formed of a magnetic material, arranged to be linearly movable between a position closing the outlet and a position opening the outlet, biased in a direction to open the outlet by the pressure of the fuel flowing in from the inlet, and having an elastic force applied in a direction to close the outlet by an elastic member; and a solenoid device having a coil, generating an electromagnetic force by passing a drive current through the coil, and driving the valve unit in a direction to open the outlet by the electromagnetic force. The method for driving a fuel injection valve includes steps of acquiring a supply pressure of the fuel supplied to the inlet, and setting values of the drive current flowing through the coil for a predetermined period including a supply start point of the drive current based on the supply pressure.

Advantages of the Invention

[0009] According to the present disclosure, it is possible to provide a fuel injection valve and a method for driving a fuel injection valve capable of suppressing the calorific value.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Mode for Carrying Out the Invention

[0011] Hereinafter, embodiments of the solenoid device and the solenoid valve of the fuel injection device according to the present disclosure will be described with reference to the drawings. Note that the present invention is not limited by this embodiment. Further, the components in the following embodiments include those that can be replaced and are easy for those skilled in the art, or those that are substantially the same.

[0012] FIG. 1 is a schematic configuration diagram showing an example of the fuel injection device 10 of the present embodiment. As shown in FIG. 1, the fuel injection device 10 is mounted on a diesel engine (internal combustion engine). The fuel injection device 10 includes a fuel pump 11, a common rail 12, and a plurality of fuel injection valves 13.

[0013] The fuel pump 11 is connected to a fuel tank 14 via a fuel line L11. The fuel pump 11 sucks the fuel stored in the fuel tank 14 from the fuel line L11, pressurizes it, and generates high-pressure fuel. The fuel pump 11 is connected to the common rail 12 via a fuel high-pressure line L12. In the present embodiment, the fuel pump 11 is a fuel supply source to which fuel is supplied. The common rail 12 holds the high-pressure fuel supplied from the fuel pump 11 at a predetermined pressure. The common rail 12 is connected to the fuel injection valves 13 via a plurality (four in the present embodiment) of fuel supply lines L13. The fuel injection valve 13 injects the high-pressure fuel in the common rail 12 into each cylinder (combustion chamber) of the diesel engine by opening and closing the solenoid valve.

[0014] FIG. 2 is a longitudinal sectional view showing an example of the fuel injection valve 13. As shown in FIG. 2, the fuel injection valve 13 has a shape extending in the axial direction of the central axis AX, and includes a main body portion 20, a solenoid valve 40, and a control portion 50. Hereinafter, when describing the configuration of the fuel injection valve 13, the side of the fuel injection port 30 in the axial direction of the central axis AX is referred to as the tip side, and the side of the solenoid valve 40 is referred to as the base end side.

[0015] The main body portion 20 includes a casing 21 and a piston valve 22. The casing 21 has a fuel inlet 24, an injection-side flow path 25, a control-side flow path 26, an injection-side pressure chamber 27, a control-side pressure chamber 28, a cylinder chamber 29, a fuel injection port 30, a fuel discharge port 31, a solenoid valve-side pressure chamber 32, and a sensor 33.

[0016] Fuel flows into the fuel inlet 24 from the fuel supply line L13. The injection-side flow path 25 connects the fuel inlet 24 and the injection-side pressure chamber 27. The control-side flow path 26 connects the fuel inlet 24 and the control-side pressure chamber 28.

[0017] The injection-side pressure chamber 27 is connected to the fuel injection port 30. The fuel injection port 30 is disposed at the end on the tip side of the casing 21 and ejects fuel toward each cylinder of the diesel engine.

[0018] The control-side pressure chamber 28 is connected to the fuel discharge port 31. The fuel discharge port 31 is disposed at the end on the base end side of the casing 21 and is connected to the solenoid valve-side pressure chamber 32. The solenoid valve-side pressure chamber 32 is connected to a solenoid valve 40 (space portion 46d described later).

[0019] The cylinder chamber 29 is connected to the injection-side pressure chamber 27 and the control-side pressure chamber 28. The cylinder chamber 29 houses the piston valve 22. The cylinder chamber 29 is connected to the solenoid valve-side pressure chamber 32 via a flow path 29a.

[0020] The piston valve 22 is accommodated in the cylinder chamber 29 and is movably provided toward the injection-side pressure chamber 27 side or the control-side pressure chamber 28 side. The piston valve 22 includes a spring seat member 22a, a control-side piston member 22b, a connecting member 22c, and a valve body 22d. The spring seat member 22a, the control-side piston member 22b, and the connecting member 22c are integrally formed. The spring seat member 22a receives the elastic force of an elastic member 23 described later. The control-side piston member 22b receives the pressure of the control-side pressure chamber 28. The connecting member 22c connects the spring seat member 22a and the control-side piston member 22b. The valve body 22d protrudes from the spring seat member 22a toward the tip side in the axial direction of the central axis AX. The valve body 22d abuts against the spring seat member 22a by the resultant force of the pressure-receiving force from each pressure chamber and the elastic force. The tip of the valve body 22d is formed in a shape capable of closing the fuel injection port 30. The valve body 22d receives the pressure of the injection-side pressure chamber 27.

[0021] When the pressure in the injection-side pressure chamber 27 is smaller than the resultant force of the pressure in the control-side pressure chamber 28 and the elastic force of the elastic member 23, the piston valve 22 is in a state of being pressed toward the injection-side pressure chamber 27. In this case, the fuel injection port 30 is in a closed state by the valve body 22d. When the pressure in the injection-side pressure chamber 27 becomes larger than the resultant force of the pressure in the control-side pressure chamber 28 and the elastic force of the elastic member 23 from this state, the piston valve 22 is in a state of being pressed toward the control-side pressure chamber 28. In this case, the valve body 22d moves away from the fuel injection port 30, and the fuel injection port 30 is in an open state.

[0022] The sensor 33 detects the supply pressure, which is the pressure of the fuel supplied to the fuel inlet 24. The sensor 33 may be configured to detect, for example, the pressure (rail pressure) of the common rail 12 as the supply pressure. The sensor 33 transmits the detected supply pressure, which is the detection result, to the control unit 50.

[0023] The solenoid valve 40 has a solenoid device 41 and a valve unit 42. FIG. 3 is a longitudinal sectional view showing an example of the solenoid valve 40. FIG. 3 shows an enlarged part of FIG. 2. As shown in FIG. 3, the solenoid device 41 drives the valve unit 42 along the axial direction of the central axis AX by electromagnetic force. The solenoid device 41 has a core 43, a coil 44, a casing 45, a cylindrical member 46, and a terminal fixing member 47.

[0024] The core 43 has a cylindrical part 43a, a flange part 43b, and a side surface part 43c. The cylindrical part 43a is formed, for example, in a cylindrical shape. The flange part 43b is, for example, in a disc shape and is arranged on the base end side of the core 43. The cylindrical part 43a and the flange part 43b are arranged such that their central axes coincide with the central axis AX of the fuel injection valve 13, respectively.

[0025] The side surface part 43c is in a cylindrical shape that encloses the cylindrical part 43a. The side surface part 43c is arranged at a radial interval from the cylindrical part 43a and extends toward the tip side. The cylindrical part 43a, the flange part 43b, and the side surface part 43c are formed using a magnetic material. The core 43 houses the coil 44 in the space surrounded by the cylindrical part 43a, the flange part 43b, and the side surface part 43c. In the core 43, the space where the coil 44 is arranged is sealed by a sealing part 49. The sealing part 49 is formed using, for example, a resin material. Further, the terminal fixing member 47 is arranged between the core 43 and the casing 45 described later in the axial direction of the central axis AX and fixes the terminal 44a connected to the coil 44. Note that the terminal 44a passes through the casing 45 and is drawn out to the outside. The terminal fixing member 47 is formed using, for example, a resin material or the like.

[0026] The coil 44 is arranged in a state of being wound around the cylindrical part 43a. The coil 44 passes through the casing 45 described later and is connected to a power supply unit (not shown). The solenoid device 41 generates an electromagnetic force by passing an electric current through the coil 44.

[0027] The casing 45 houses the core 43 and the coil 44. The casing 45 is formed using, for example, a resin material. The casing 45 has a support portion 45a that supports an elastic member 48 described later.

[0028] The cylindrical member 46 is disposed on the inner peripheral side of the core 43. The cylindrical member 46 is formed using, for example, a metal material. The cylindrical member 46 may be a non-magnetic metal. The cylindrical member 46 is, for example, cylindrical and is arranged such that its central axis coincides with the central axis AX of the fuel injection valve 13. The cylindrical member 46 is arranged at a position where the end face 46b on the tip side can contact the valve unit 42. In the present embodiment, the end face 46b is flush with, for example, the tip-side end face of the side surface portion 43c of the core 43 and the tip-side end face of the sealing portion 49.

[0029] The elastic member 48 is housed on the inner peripheral side of the cylindrical member 46 with the end portion on the base end side supported by the support portion 45a of the casing 45. The elastic member 48 applies an elastic force toward the tip side in the axial direction of the central axis AX to the valve unit 42.

[0030] The valve unit 42 moves in the axial direction of the central axis AX by the electromagnetic force generated by the solenoid device 41. The valve unit 42 includes an armature 42a, a valve body 42b, and a stepped portion 42c. The armature 42a is formed using a magnetic material. The armature 42a is, for example, disc-shaped. The armature 42a is disposed to face the end portion on the tip side of the core 43 of the solenoid device 41. The valve body 42b extends from the armature 42a toward the tip side. The tip of the valve body 42b is formed in a shape capable of closing the fuel discharge port 31. The valve body 42b may be formed of a magnetic material or a non-magnetic material. The stepped portion 42c is formed in a state where the central portion of the armature 42a protrudes toward the solenoid device 41 side. The stepped portion 42c is formed in a shape and dimensions that contact the end face 46b of the cylindrical member 46 when the valve unit 42 is attracted toward the solenoid device 41 side. Further, the stepped portion 42c receives the elastic force from the elastic member 48. The elastic force of the elastic member 48 is transmitted to the armature 42a and the valve body 42b via the stepped portion 42c. The elastic force of the elastic member 48 is applied to the armature 42a and the valve body 42b toward the tip side in the axial direction of the central axis AX.

[0031] The control unit 50 controls the operation of the solenoid device 41. The control unit 50 includes a processing device such as a CPU (Central Processing Unit) and a storage device such as a RAM (Random Access Memory) or a ROM (Read Only Memory). The control unit 50 includes a supply pressure acquisition unit 51, a drive current control unit 52, and a storage unit 53.

[0032] The supply pressure acquisition unit 51 acquires the supply pressure of the fuel supplied to the fuel inlet 24. The supply pressure acquisition unit 51 can acquire the detection result of the sensor 33 as the supply pressure. Further, the supply pressure acquisition unit 51 may be able to acquire an operation map indicating the operation content of the fuel injection device 10 from an ECU (Electronic Control Unit, not shown) that controls the fuel injection device 10. In this case, the supply pressure acquisition unit 51 may be configured to extract the supply pressure based on the acquired operation map and acquire the extracted supply pressure.

[0033] The drive current control unit 52 controls the drive current supplied to the coil 44 of the solenoid device 41 according to the supply voltage acquired by the supply voltage acquisition unit 51. FIG. 4 is a diagram showing an example of a profile of the drive current supplied to the coil 44. As shown in FIG. 4, the drive current I includes an inrush current I1, a pull-up current I2, and a hold current I3.

[0034] The inrush current I1 is passed through the coil 44 during an inrush period t1 which is the first period including the supply start time point t0 in time series. The inrush current I1 is generated, for example, as shown in FIG. 4, by a pulse signal whose period covers the entire inrush period t1 as a control signal. The inrush current I1 serves as a drive current for generating an electromagnetic force to separate the valve unit 42 that closes the fuel discharge port 31.

[0035] The pull-up current I2 is passed through the coil 44 during a pull-up period t2 after the inrush current I1 has flowed, that is, after the elapse of the inrush period t1. The pull-up current I2 has a lower peak current value than the inrush current I1. The pull-up current I2 serves as a drive current for generating an electromagnetic force to attract the valve unit 42 separated from the fuel discharge port 31 toward the core 43 side. The pull-up current I2 is generated by a plurality of pulse signals as control signals.

[0036] The hold current I3 is passed through the coil 44 during a hold period t3 after the pull-up current I2 has flowed, that is, after the elapse of the pull-up period t2. The hold current I3 is generated by a plurality of pulse signals as control signals. The hold current I3 serves as a drive current for generating an electromagnetic force to hold the valve unit 42 attracted toward the core 43 side. The hold current I3 has a lower peak current value than the inrush current I1 and the pull-up current I2.

[0037] The drive current control unit 52 variably sets the value of the drive current I during a predetermined period including the supply start time point t0 according to the acquired supply voltage. The higher the acquired supply voltage, the smaller the value of the drive current I during the predetermined period, and the lower the acquired supply voltage, the larger the value of the drive current I during the predetermined period.

[0038] Figure 5 is a diagram showing an example of the drive current controlled by the drive current control unit 52. As shown in Figure 5, the drive current control unit 52 can variably set, for example, the values of the inrush period t1 and the pull-up period t2 as a predetermined period including the supply start time point t0 among the drive current I. As shown in Figure 5, the higher the acquired supply voltage, the smaller the values of the inrush current I1 during the inrush period t1 and the pull-up current I2 during the pull-up period t2 can be (drive current IA). Also, the lower the acquired supply voltage, the larger the values of the inrush current I1 during the inrush period t1 and the pull-up current I2 during the pull-up period t2 can be (drive current IB). The values of the drive current I, IA, and IB can be set so that the valve unit 42 can be attracted toward the core 43 by the generated electromagnetic force. That is, the values of the drive current I, IA, and IB can be set so that the force acting toward the proximal end side of the valve unit 42 (the elastic force from the elastic member 48, the electromagnetic force generated in the solenoid device 41) is larger than the force acting toward the distal end side of the valve unit 42 (the pressure receiving force from the control side pressure chamber 28). Note that the drive current control unit 52 is not limited to a configuration that controls the inrush current I1 and the pull-up current I2 as shown in Figure 5 in three steps, and may be a configuration that controls them in two steps or four steps or more.

[0039] The memory unit 53 stores various types of information. The memory unit 53 has a storage such as a hard disk drive, a solid state drive, etc. Note that an external storage medium such as a removable disk may be used as the memory unit 53. In the present embodiment, the memory unit 53 stores a data table that defines the correspondence relationship between the acquired supply pressure and the drive current I. FIG. 6 is a diagram showing an example of the data table stored in the memory unit 53. As shown in FIG. 6, the memory unit 53 stores a data table in which the values of the drive current are associated with each supply pressure. The drive current control unit 52 described above can set the value of the drive current corresponding to the supply pressure based on the data table stored in the memory unit 53.

[0040] The operation of the fuel injection valve 13 configured as described above will be described. When no current is passed through the coil 44 of the solenoid device 41, no electromagnetic force is generated in the solenoid device 41. In this case, in the valve unit 42, the valve body 42b presses the fuel discharge port 31 toward the tip side by the elastic force of the elastic member 48. As a result, the fuel discharge port 31 is in a closed state.

[0041] In a state where the fuel discharge port 31 is closed, the resultant force of the pressure in the control side pressure chamber 28 and the elastic force of the elastic member 23 becomes larger than the pressure in the injection side pressure chamber 27. For this reason, the piston valve 22 presses and closes the fuel injection port 30.

[0042] Also, when a current is passed through the coil 44 of the solenoid device 41, an electromagnetic force is generated in the solenoid device 41. FIG. 7 is a longitudinal sectional view showing an example of the operation of the electromagnetic valve 40. FIG. 7 shows an example when a current is passed through the coil 44. As shown in FIG. 7, when an electromagnetic force is generated in the solenoid device 41, in the valve unit 42, the armature 42a is attracted toward the core 43 by the electromagnetic force, and the valve body 42b moves away from the fuel discharge port 31. As a result, the fuel discharge port 31 is in an open state.

[0043] When the fuel discharge port 31 opens, the pressure in the control-side pressure chamber 28 decreases. When the resultant force of the pressure received by the control-side pressure chamber 28 and the elastic force of the elastic member 23 becomes smaller than the pressure received by the injection-side pressure chamber 27, the piston valve 22 moves toward the control-side pressure chamber 28. In this case, the valve body 22d of the piston valve 22 separates from the fuel injection port 30 and the fuel injection port 30 opens. When the fuel injection port 30 is in the open state, the fuel that has flowed through the injection-side flow path 25 from the fuel inlet 24 and has flowed into the injection-side pressure chamber 27 is injected from the fuel injection port 30.

[0044] In the above operation, when the valve unit 42 is attracted toward the core 43 by the electromagnetic force of the solenoid device 41, as shown in FIG. 7, the stepped portion 42c of the valve unit 42 contacts the end face 46b of the cylindrical member 46. In this case, the cylindrical member 46 functions as a stopper that restricts the movement of the valve unit 42 toward the proximal end side.

[0045] Also, in the above operation, the pressure in the control-side pressure chamber 28 changes according to the supply pressure of the fuel supplied to the fuel inlet 24 of the fuel injection valve 13. That is, the higher the supply pressure, the higher the pressure in the control-side pressure chamber 28, and the lower the supply pressure, the lower the pressure in the control-side pressure chamber 28. When the pressure in the control-side pressure chamber 28 is high, the biasing force toward the core 43 side with respect to the valve unit 42 increases. Also, when the pressure in the control-side pressure chamber 28 is low, the biasing force toward the core 43 side with respect to the valve unit 42 decreases.

[0046] When no electromagnetic force is generated in the solenoid device 41, the elastic force from the elastic member 48 and the pressure in the control-side pressure chamber 28 act on the valve unit 42. The elastic member 48 is configured to apply an elastic force greater than the pressure that can be received in the control-side pressure chamber 28 to the valve unit 42 so that the valve unit 42 can maintain the state of closing the fuel discharge port 31 in this state.

[0047] In recent years, during the operation of the fuel injection device 10, it has been required to operate with a higher maximum value of the supply pressure in the common rail 12, that is, to increase the pressure of the common rail 12. When increasing the pressure of the common rail 12, in order to prevent the fuel discharge port 31 from opening due to the supply pressure, it is necessary to increase the elastic force of the elastic member 48 acting on the valve unit 42 corresponding to the maximum value of the supply pressure.

[0048] On the other hand, when operating the fuel injection device 10, for example, there is a period during which the operation is performed with a low supply pressure. When the supply pressure is low, the pressure in the control-side pressure chamber 28 becomes low. Since the elastic force of the elastic member 48 is set corresponding to the maximum value of the supply pressure, in order to separate the valve unit 42 from the fuel discharge port 31, it is necessary to generate a larger electromagnetic force. That is, it is necessary to pass a larger current through the coil 44.

[0049] When passing a large driving current through the coil 44 as described above, the heat generation amount in the coil 44 increases, and the heat load in the solenoid device 41 becomes high. In such a solenoid device 41 that needs to generate such a large electromagnetic force, a cooling mechanism for cooling the solenoid device 41 is separately required.

[0050] On the contrary, in the fuel injection device 10 according to the present embodiment, it is possible to suppress the heat generation amount in the coil 44 by adjusting the driving current flowing through the coil 44 according to the supply pressure of the fuel supplied to the fuel inlet 24. The control unit 50 variably sets the value of a predetermined period including the supply start time point t0 of the driving current flowing through the coil 44 according to the supply pressure of the fuel supplied to the fuel inlet 24.

[0051] FIG. 8 is a flowchart showing an example of the operation of the fuel injection device 10 according to the present embodiment. As shown in FIG. 8, the supply pressure acquisition unit 51 of the control unit 50 acquires the supply pressure of the fuel supplied to the fuel inlet 24 (step S10). The supply pressure acquisition unit 51 acquires at least one of the detection result of the sensor 33 and the supply pressure extracted from an operation map of an ECU (not shown).

[0052] Next, based on the acquired supply pressure, the drive current control unit 52 selects a drive current I corresponding to the supply pressure from a data table stored in the storage unit 53 (step S20). After selecting the drive current I, the drive current control unit 52 controls so that the selected drive current I flows through the coil 44 (step S30).

[0053] By this control, a drive current can be passed through the coil 44 so that a minimum necessary electromagnetic force for attracting the valve unit 42 toward the core 43 is generated according to the supply pressure of the fuel supplied to the fuel inlet 24. Therefore, compared with the conventional configuration that supplies a constant drive current regardless of the supply pressure, the amount of heat generation in the coil 44 is reduced.

[0054] As described above, the fuel injection valve 13 according to the present embodiment includes a main body portion 20 having a fuel inlet 24 into which fuel supplied from the fuel pump 11 flows, a flow path (injection side flow path 25, control side flow path 26) through which the fuel flowing in from the fuel inlet 24 circulates, and a fuel outlet 31 connected to the flow path (25, 26) for discharging fuel; a valve unit 42 at least partially formed using a magnetic material, arranged to be linearly movable between a position closing the fuel outlet 31 and a position opening it, biased in a direction to open the fuel outlet 31 by the pressure of the fuel flowing in from the fuel inlet 24, and elastically biased in a direction to close the fuel outlet 31 by an elastic member 48; a solenoid device 41 having a coil 44, generating an electromagnetic force by passing a drive current through the coil 44, and driving the valve unit 42 in a direction to open the fuel outlet 31 by the electromagnetic force; and a control unit 50 that variably sets the value of a predetermined period including the supply start time point t0 of the drive current among the drive currents passed through the coil 44 according to the supply pressure of the fuel supplied to the fuel inlet 24.

[0055] Also, regarding the fuel injection valve 13 according to the present embodiment driveThe method is a driving method of a fuel injection valve including: a main body portion 20 having a fuel inlet 24 into which fuel supplied from a fuel pump 11 flows, an injection side flow path 25 through which the fuel flowing in from the fuel inlet 24 circulates, a control side flow path 26, and a fuel outlet 31 that is connected to the injection side flow path 25 and the control side flow path 26 and injects fuel; a valve unit 42 formed using a magnetic body, arranged to be linearly movable between a position closing the fuel outlet 31 and a position opening the fuel outlet 31, biased in a direction to open the fuel outlet 31 by the pressure of the fuel flowing in from the fuel inlet 24, and having an elastic force applied in a direction to close the fuel outlet 31 by an elastic member 48; and a solenoid device 41 having a coil 44, generating an electromagnetic force by flowing a drive current through the coil 44, and driving the valve unit 42 in a direction to open the fuel outlet 31 by the electromagnetic force. The method includes: a step of obtaining a supply pressure of the fuel supplied to the fuel inlet 24; and a step of setting values of the drive current flowing through the coil 44 for a predetermined period including a supply start time point t0 of the drive current based on the supply pressure.

[0056] According to this configuration, it is possible to set the drive current flowing through the coil 44 so that the minimum necessary electromagnetic force for attracting the valve unit 42 toward the core 43 side is generated according to the supply pressure of the fuel supplied to the fuel inlet 24. Thereby, it becomes possible to suppress the amount of heat generation in the coil 44.

[0057] In the fuel injection valve 13 according to the present embodiment, the control unit 50 decreases the value of the drive current for a predetermined period as the supply pressure is higher, and increases the value of the drive current for a predetermined period as the supply pressure is lower. According to this configuration, it is possible to more reliably generate the minimum necessary electromagnetic force for attracting the valve unit 42 toward the core 43 side.

[0058] In the fuel injection valve 13 according to the present embodiment, the drive current includes an inrush current I1 that flows through the coil 44 during an inrush period t1, which is the first period including the supply start time point t0 in time series, a pull-up current I2 that flows during a pull-up period t2 after the inrush current I1 has flowed, and a hold current I3 that flows during a hold period t3 after the pull-up current I2 has flowed. The control unit 50 decreases the values of the inrush current I1 and the pull-up current I2 as the supply pressure increases, and increases the values of the inrush current I1 and the pull-up current I2 as the supply pressure decreases. According to this configuration, it is possible to efficiently generate the minimum necessary electromagnetic force for attracting the valve unit 42 toward the core 43.

[0059] The fuel injection valve 13 according to the present embodiment further includes a sensor 33 that detects the supply pressure, and the control unit 50 sets the value of the drive current for a predetermined period based on the detection result of the sensor 33. According to this configuration, it is possible to flexibly set the value of the drive current according to the detection result of the sensor 33.

[0060] In the fuel injection valve 13 according to the present embodiment, the control unit 50 can acquire an operation map indicating the operation content of the fuel pump 11, extracts the supply pressure based on the acquired operation map, and sets the value of the drive current for a predetermined period based on the extracted supply pressure. According to this configuration, by extracting the supply pressure based on the operation map, it is possible to set the value of the drive current according to the operation situation.

[0061] The fuel injection valve 13 according to the present embodiment further includes a storage unit 53 that stores a data table defining the correspondence relationship between the supply pressure and the drive current, and the control unit 50 sets the drive current for a predetermined period corresponding to the supply pressure based on the data table stored in the storage unit 53. According to this configuration, it is possible to efficiently set the drive voltage corresponding to the supply pressure.

[0062] The technical scope of the present invention is not limited to the above-described embodiments, and appropriate modifications can be made without departing from the spirit of the present invention. For example, in the above-described embodiment, the electromagnetic valve 40 is described by taking as an example the configuration provided in the fuel injection valve 13 of the fuel injection device 10, but it is not limited thereto. The electromagnetic valve 40 may be provided at other parts of the fuel injection device 10.

[0063] Also, the form of the fuel injection device 10 and the form of the fuel pump 11 are not limited to the above-described embodiments. For example, the number of the common rail 12 and the fuel injection valves 13, the connection position of the fuel pump 11, etc. can be set as appropriate.

[0064] Also, in the above-described embodiment, the case where the inrush current I1 and the pull-up current I2 in the drive current I can be variably set is described by taking as an example, but it is not limited thereto. For example, the hold current I3 may be variably set. Also, only the inrush current I1 variable may be settable.

Explanation of Reference Numerals

[0065] 10 Fuel injection device 11 Fuel pump 12 Common rail 13 Fuel injection valve 14 Fuel tank 20 Main body part 21, 45 Casing 22 Piston valve 22a Spring seat member 22b Control side piston member 22c Connecting member 22d, 42b Valve body 23, 48 Elastic member 24 Fuel inlet 25 Injection side flow path 26 Control side flow path 27 Injection side pressure chamber 28 Control side pressure chamber 29 Cylinder chamber 30 Fuel injection port 31 Fuel discharge port 32 Electromagnetic valve side pressure chamber 33 Sensor 40 Electromagnetic valve 41 Solenoid device 42 Valve unit 42a Armature 43 Core 43a Cylindrical part 43b Flange part 43c Side surface part 44 Coil 44a Terminal 45a Support part 46 Cylindrical member 46b End face 47 Terminal fixing member 49 Sealing part 50 Control part 51 Supply pressure acquisition part 52 Drive current control part 53 Memory part AX Central axis I, IA, IB Drive current I1 Inrush current I2 Pull-up current I3 Hold current L11 Fuel line L12 Fuel high-pressure line L13 Fuel supply line t0 Supply start time t1 Inrush period t2 Pull-up period t3 Hold period

Claims

1. A main body portion having an inlet through which fuel supplied from a fuel supply source flows in, a flow path through which the fuel flowing in from the inlet circulates, and an outlet connected to the flow path for discharging the fuel; A valve unit formed of at least a part using a magnetic material, arranged to be linearly movable between a position closing the outlet and a position opening the outlet, biased in a direction to open the outlet by the pressure of the fuel flowing in from the inlet, and having an elastic force applied in a direction to close the outlet by an elastic member; A solenoid device having a coil, generating an electromagnetic force by passing a drive current through the coil, and driving the valve unit in a direction to open the outlet by the electromagnetic force; A control unit variably setting a value of the drive current flowing through the coil during a predetermined period including a start point of supply of the drive current according to the supply pressure of the fuel supplied to the inlet and comprising; The solenoid device has a core formed in a cylindrical shape and having a facing surface facing the valve unit, a cylindrical member disposed on the inner peripheral surface of the core, and a casing housing the core and the cylindrical member; The valve unit has an armature facing the facing surface, the armature having a stepped portion extending from a surface facing the core toward the core, the armature coming into contact with the cylindrical member and the stepped portion when being driven by the solenoid device, the casing including an outer peripheral portion covering the outer peripheral surface of the core, a proximal-side bottom portion including a support portion connected to an end of the outer peripheral portion opposite to the valve unit for supporting the elastic member, and an inner peripheral portion protruding toward the valve unit side so as to surround the elastic member from the proximal-side bottom portion for supporting the cylindrical member; the coil is connected to a terminal provided to penetrate the proximal-side bottom portion of the casing, and a terminal fixing member for fixing the terminal is disposed between the outer peripheral portion and the inner peripheral portion of the casing and between the core and the proximal-side bottom portion; A fuel injection valve.

2. The control unit makes the value of the drive current during the predetermined period smaller as the supply pressure is higher, and makes the value of the drive current during the predetermined period larger as the supply pressure is lower. The fuel injection valve according to Claim 1.

3. The drive current includes an inrush current that flows through the coil during an inrush period, which is the first period including the supply start point in a time series, a pull-up current that flows during a pull-up period after the inrush current has flowed, and a hold current that flows during a hold period after the pull-up current has flowed. The control unit decreases the values of the inrush current and the pull-up current as the supply pressure increases, and increases the values of the inrush current and the pull-up current as the supply pressure decreases. The fuel injection valve according to claim 2.

4. Further comprising a sensor for detecting the supply pressure. The control unit sets the value of the drive current for the predetermined period based on the detection result of the sensor. The fuel injection valve according to any one of claims 1 to 3.

5. The control unit can acquire an operation map indicating the operation content of the fuel supply source, extracts the supply pressure based on the acquired operation map, and sets the value of the drive current for the predetermined period according to the extracted supply pressure. The fuel injection valve according to any one of claims 1 to 4.

6. Further comprising a storage unit that stores a data table defining the correspondence between the supply pressure and the drive current. The control unit sets the drive current for the predetermined period corresponding to the supply pressure based on the data table stored in the storage unit. The fuel injection valve according to any one of claims 1 to 5.

7. A main body portion having an inlet through which fuel supplied from a fuel supply source flows in, a flow path through which the fuel flowing in from the inlet circulates, and an outlet connected to the flow path for discharging the fuel. A valve unit formed at least partially using a magnetic material, arranged to be linearly movable between a position closing the outlet and a position opening the outlet, biased in a direction to open the outlet by the pressure of the fuel flowing in from the inlet, and having an elastic force applied in a direction to close the outlet by an elastic member. A solenoid device having a coil, generating an electromagnetic force by flowing a drive current through the coil, and driving the valve unit in a direction to open the outlet by the electromagnetic force. The solenoid device A core formed in a cylindrical shape and having a facing surface facing the valve unit. A cylindrical member disposed on the inner peripheral surface of the core. A casing that houses the core and the cylindrical member. The valve unit Having an armature facing the facing surface. The armature has a stepped portion extending from a surface facing the core toward the core. When the armature is driven by the solenoid device, it contacts the cylindrical member at the stepped portion. The casing includes an outer peripheral portion covering the outer peripheral surface of the core, a proximal end side bottom portion including a support portion connected to an end of the outer peripheral portion opposite to the valve unit and supporting the elastic member, and an inner peripheral portion protruding toward the valve unit side so as to surround the elastic member from the proximal end side bottom portion and supporting the cylindrical member. The coil is connected to a terminal provided through the proximal end side bottom portion of the casing. A terminal fixing member for fixing the terminal is disposed between the outer peripheral portion and the inner peripheral portion of the casing and between the core and the proximal end side bottom portion. A method for driving a fuel injection valve, a step of obtaining a supply pressure of the fuel supplied to the inlet, a step of setting values of a driving current flowing through the coil for a predetermined period including a supply start point of the driving current based on the supply pressure and including the method for driving a fuel injection valve.

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