JP2016156311A - Fuel injection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection device capable of expanding a dynamic range of fuel injection.SOLUTION: A CNG injector 47 includes a spring constituted by a first elastic part having first elastic force and a second elastic part having second elastic force larger than the first elastic force, and a solenoid coil compressing the spring 67 to a valve open side. The CNG injector 47 is opened at a first opening valve rate when the first elastic part is compressed, and is opened at a second opening valve rate larger than the first opening valve rate when the second elastic part is compressed. An ECU 100 controls the CNG injector 47 to open at the first opening valve rate or the second opening valve rate by increasing or decreasing exciting current or exciting voltage to the solenoid coil.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fuel injection device that injects fuel into an internal combustion engine.

  In recent years, in vehicles such as automobiles, CNG automobiles that use gas fuel such as CNG (Compressed Natural Gas) or bi-fuel automobiles that switch between CNG and gasoline have been developed.

  This type of conventional vehicle is equipped with a fuel injection device, and the fuel injection device can control the injector only in a fully closed state or a fully open state, so that the pressure of the fuel supplied to the injector is kept constant. Meanwhile, the fuel injection amount is controlled by adjusting the valve opening time of the injector (see Patent Document 1).

JP 2011-153529 A

  However, since the composition of CNG has a large difference depending on the production area, etc., compared with gasoline, the conventional fuel injection device described in Patent Document 1 is a value obtained by dividing the maximum injection amount of the injector by the minimum injection amount. There was a problem that the dynamic range was not large enough to handle all engine operating conditions.

  For example, the conventional fuel injection device cannot operate the engine well within the dynamic range of the injector depending on the composition of CNG, and there is a possibility that the emission may be increased or the power performance may be deteriorated.

  In addition, since the conventional fuel injection device injects high-pressure CNG, which is gas fuel, into the air, particularly when the required injection amount is small, the intake of air is inhibited by the high-pressure injected CNG, and an appropriate air-fuel mixture is obtained. There was a possibility that could not be obtained.

  The problem due to the limitation of the dynamic range exists not only when the fuel is CNG but also when the fuel is gasoline. For example, in a fuel injection device that injects gasoline, since fuel injection near the minimum injection amount is unstable, there is a possibility that the engine cannot be operated satisfactorily when the required injection amount is small.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a fuel injection device capable of expanding the dynamic range of fuel injection.

  In order to achieve the above object, the present invention provides a fuel injection device including an injector that injects fuel into an internal combustion engine, and a control unit that controls driving of the injector, wherein the injector has a first elastic force. A first elastic portion; a spring composed of a second elastic portion having a second elastic force greater than the first elastic force; and a solenoid coil that compresses the spring toward the valve opening side. The elastic part is compressed to open at a first valve opening rate, and the second elastic part is compressed to open at a second valve opening rate larger than the first valve opening rate, and the control unit However, the injector is controlled to open at the first valve opening rate or the second valve opening rate by increasing or decreasing the exciting current or exciting voltage to the solenoid coil.

  According to the present invention, the injector can be accurately opened at the first valve opening rate or the second valve opening rate by increasing or decreasing the exciting current or exciting voltage to the solenoid coil. For this reason, the dynamic range can be expanded.

FIG. 1 is a configuration diagram showing a main part of a vehicle equipped with a fuel injection device according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing the configuration of the CNG injector of the fuel injection device according to the embodiment of the present invention. FIG. 3A is a cross-sectional view showing a spring of a CNG injector of the fuel injection device according to the embodiment of the present invention, and FIG. 3B is a view showing a spring characteristic of the spring. FIG. 4 is a timing chart showing time-series changes in the excitation current to the CNG injector and the valve opening rate of the fuel injection device according to the embodiment of the present invention. FIG. 5 is a flowchart showing a flow of high flow rate determination processing executed by the fuel injection device according to the embodiment of the present invention. FIG. 6 is a flowchart showing the flow of the fuel composition adjustment determination process executed by the fuel injection device according to the embodiment of the present invention.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 6. As shown in FIG. 1, a vehicle 1 equipped with a fuel injection device according to an embodiment of the present invention includes an internal combustion engine 10, a fuel supply device 20, and an ECU 100 as a control unit.

  The internal combustion engine 10 is a bi-fuel internal combustion engine that can use CNG as gas fuel and gasoline as liquid fuel. Therefore, the vehicle 1 is a bi-fuel vehicle.

  The internal combustion engine 10 includes an air cleaner (not shown), a throttle valve 11, a surge tank 12, and an intake manifold 14 in order from the upstream side to the downstream side in the air passage direction.

  The air flowing into the surge tank 12 is diverted to the intake manifolds 14 individually corresponding to a plurality (four in this embodiment) of cylinders 13 provided in the internal combustion engine 10. In the intake manifold 14, a mixed fuel obtained by mixing the fuel (CNG or gasoline) supplied by the fuel supply device 20 and air is generated, and this mixed fuel is supplied into the cylinder 13.

  In each cylinder 13, four processes are performed in order. Specifically, the mixed fuel is supplied into the cylinder 13 via the intake valve 16 at the timing when the piston 15 moves downward from the top dead center in FIG. 1 (intake process). In the cylinder 13 supplied with the mixed fuel, the mixed fuel is compressed by the upward movement of the piston 15 in FIG. 1 (compression process).

  After that, at the timing when the piston 15 that has reached the top dead center starts to move downward again in FIG. To the crankshaft 17 (combustion process).

  Thereafter, the crankshaft 17 is rotated in a specified direction by the transmitted propulsive force, and the piston 15 that has reached the bottom dead center is moved upward in FIG. 1, and the exhaust gas that is the burned mixed fuel is discharged into the exhaust valve. 18 is exhausted to the outside of the cylinder 13 via an exhaust 18 (exhaust process).

  Next, the fuel supply device 20 will be described. The fuel supply device 20 includes a gasoline supply system 30 for supplying gasoline stored in the gasoline tank 31 to each cylinder 13 of the internal combustion engine 10, and CNG stored in the CNG tank 41 at high pressure for each cylinder of the internal combustion engine 10. 13 is provided with a CNG supply system 40 for supplying to the apparatus 13.

  The gasoline supply system 30 is provided with a fuel pump 32 for sucking gasoline from the gasoline tank 31 and a gasoline delivery pipe 33 to which fuel discharged from the fuel pump 32 is pumped. The gasoline delivery pipe 33 is provided with a gasoline injector 34.

  In the gasoline injector 34, the ECU 100 controls the injection timing of the gasoline into the intake manifold 14 and the length of the injection time.

  The CNG supply system 40 is provided with a high-pressure fuel pipe 42 connected to the CNG tank 41 and a CNG delivery pipe 43 connected to a downstream end (right end in FIG. 1) of the high-pressure fuel pipe 42.

  A main valve 44 having a normally closed electromagnetic valve is provided between the high pressure fuel pipe 42 and the CNG tank 41. The main valve 44 is opened and closed by the ECU 100. When the main valve 44 is in a closed state, the inside of the CNG tank 41 is in a sealed state.

  Further, the high-pressure fuel pipe 42 is provided with a shut-off valve 45 on the downstream side (right side in FIG. 1) of the main valve 44. The shut-off valve 45 is opened and closed by the ECU 100. When both the main valve 44 and the shutoff valve 45 are open, the CNG in the CNG tank 41 is supplied to the CNG delivery pipe 43 through the high-pressure fuel pipe 42. When the shut-off valve 45 is closed, CNG is not supplied to the CNG delivery pipe 43.

  The high-pressure fuel pipe 42 is provided with a regulator 46 on the downstream side of the shutoff valve 45. The regulator 46 reduces the pressure of the CNG supplied from the CNG tank 41 (that is, the upstream side), that is, the fuel pressure. The regulator 46 operates so that CNG having a prescribed fuel pressure is supplied to the CNG delivery pipe 43.

  The CNG delivery pipe 43 is provided with a CNG injector 47 as an injector in the present invention. The CNG injector 47 injects CNG into each intake manifold 14 individually corresponding to each cylinder 13 of the internal combustion engine 10. To do. In the present embodiment, four CNG injectors 47 are provided in the CNG delivery pipe 43.

  In the CNG injector 47, the ECU 100 controls the timing of CNG injection to the intake manifold 14 and the length of the injection time.

  Next, the CNG injector 47 will be described. As shown in FIG. 2, the CNG injector 47 of the present embodiment is a so-called normally closed electromagnetic valve. The CNG injector 47 includes a substantially cylindrical main body housing 60.

  A closing member 63 is provided on one end side (upper side in FIG. 2) of the main body housing 60 in the axial direction (the vertical direction in FIG. 2 and the direction in which the axis 61 indicated by a one-dot chain line extends). 63 closes one end of a through-hole 62 provided in the main body housing 60.

  A bobbin 64 and a solenoid coil 66 wound around the outer periphery of the bobbin 64 are provided in the through hole 62 at an intermediate position in the axial direction. A spring 67 is provided on the inner peripheral side of the bobbin 64 so as to be extendable and contractable in the axial direction. One end side of the spring 67 is supported by the closing member 63.

  Further, a valve body 69 is provided on the other end side (lower side in FIG. 2) in the axial direction of the main body housing 60, and the valve body 69 has an accommodation hole 68. One end portion of the valve body 69 is located in the through hole 62 of the main body housing 60. The other end of the valve body 69 is located outside the main body housing 60 (that is, below the main body housing 60 in FIG. 2).

  The valve body 69 supports a movable iron core 70, and the movable iron core 70 slides in the axial direction within the accommodation hole 68. The movable iron core 70 is always given a biasing force toward the other side (downward in FIG. 2) in the axial direction by a spring 67.

  The movable iron core 70 is slid to one side (the upper side in FIG. 2) in the axial direction against the biasing force from the spring 67 by the electromagnetic force generated by the solenoid coil 66 when electric power is supplied to the solenoid coil 66. Move (move).

  Further, in the accommodation hole 68, a valve body 71 provided so as to be slidable integrally with the movable iron core 70 and an opening on the other side (lower side in FIG. 2) in the axial direction of the accommodation hole 68 are closed. The valve seat 72 is provided. The valve seat 72 is provided with an injection port 73.

  The injection port 73 is closed by the valve body 71 when electric power is not supplied to the solenoid coil 66. Therefore, when power is not supplied to the solenoid coil 66, CNG is not injected from the CNG injector 47 into the internal combustion engine 10.

  On the other hand, when electric power is supplied to the solenoid coil 66, the movable iron core 70 and the valve body 71 are moved away from the valve seat 72 by the electromagnetic force generated from the solenoid coil 66, and the injection port 73 is opened. . Therefore, when electric power is supplied to the solenoid coil 66, CNG supplied from the suction port (not shown) into the CNG injector 47 is injected from the injection port 73 into the internal combustion engine 10.

  Here, as shown in FIG. 3A, the spring 67 of the present embodiment has a first elastic portion 67A having a first elastic force and a second elastic force having a second elastic force larger than the first elastic force. It is comprised as a compression coil spring which consists of 2 elastic parts 67B.

  Therefore, as shown in FIG. 3B, the spring 67 has a non-linear characteristic. When the load P1 is applied, the deflection is δ1, and when the load P2 is applied, the deflection is δ2. .

  3A and 3B, the spring 67 has a deflection of δ1 due to the compression of the first elastic portion 67A when the load P1 is applied, and the second elasticity when the load P2 is applied. The deflection becomes δ2 by further compressing the portion 67B.

Here, the respective spring constants k of the first elastic portion 67A and the second elastic portion 67B are expressed by the following mathematical formula (1).

According to Equation (1), in order to increase the elastic force of the second elastic portion 67B from the first elastic portion 67A, the first elastic portion 67A and the second elastic portion 67B may be made of different materials.
Further, when the same material is used, for example, the wire diameter d of the second elastic portion 67B may be made larger than that of the first elastic portion 67A. Alternatively, the average coil diameter D of the second elastic portion 67B may be made smaller than that of the first elastic portion 67A. Alternatively, the length L2 of the second elastic portion 67B may be shorter (the number of turns) than the length L1 of the first elastic portion 67A.

  In the present embodiment, the CNG injector 47 is driven by current control. The current supplied to the solenoid coil 66 is switched to a predetermined low current (hereinafter simply referred to as a low current) or a predetermined high current (hereinafter simply referred to as a high current).

  The CNG injector 47 may be driven by voltage control. In this case, the voltage supplied to the solenoid coil 66 is switched to a predetermined low voltage or a predetermined high voltage.

  When the exciting current supplied to the solenoid coil 66 is a low current, the solenoid coil 66 generates a load P1. In this case, the load P1 acts on the spring 67 and the first elastic portion 67A of the spring 67 is compressed, so that the deflection of the spring 67 becomes δ1, and the valve opening rate of the CNG injector 47 becomes the first valve opening rate. Become.

  On the other hand, when the exciting current supplied to the solenoid coil 66 is a high current, the solenoid coil 66 generates a load P2. In this case, the load P2 is applied to the spring 67, and the second elastic portion 67B is further compressed in addition to the first elastic portion 67A of the spring 67, so that the deflection of the spring 67 becomes δ2, and the CNG injector 47 is opened. The valve rate becomes a second valve opening rate larger than the first valve opening rate.

  The CNG injector 47 can be accurately opened at the first valve opening rate or the second valve opening rate by configuring the spring 67 from the first elastic portion 67A and the second elastic portion 67B as described above. . Here, the second valve opening rate is, for example, fully open, that is, a valve opening rate of 100%. The first valve opening rate is, for example, a valve opening rate of 50%.

  As shown in FIG. 4, the CNG injector 47 is opened when an excitation current is supplied from the ECU 100 to the solenoid coil 66. In FIG. 4, the excitation current indicates a low current by a broken line and a high current by a solid line. The injector valve opening rate indicates the valve opening rate when a low current is supplied by a broken line, and indicates the valve opening rate when a high current is supplied by a solid line.

  When the exciting current is a low current indicated by a broken line, the CNG injector 47 opens at the first valve opening rate by compressing the first elastic portion 67A. Further, when the exciting current is a high current indicated by a solid line, the CNG injector 47 opens at a second valve opening rate larger than the first valve opening rate by further compressing the second elastic portion 67B.

  The exciting current supplied to the CNG injector 47 is classified into an overexciting current and a holding current. The overexcitation current is an excitation current for applying a valve opening force necessary for opening the CNG injector 47 in the valve closing state. The holding current is an exciting current that gives a holding force necessary for holding the valve open state to the CNG injector 47 that has been opened due to the supply of the overexcitation current.

  The valve opening force required to open the CNG injector 47 is smaller than the holding force required to hold the valve open state. Therefore, the holding current is set to a current value smaller than the overexcitation current.

  In the present embodiment, the high and low excitation currents differ depending on whether the holding current is high or low, and the overexcitation currents are equal. Therefore, when opening the CNG injector 47 to the first valve opening rate, the valve opening state can be opened from the closed state to the first valve opening rate in a shorter time than when opening to the second valve opening rate. Good sex.

  Further, since the overexcitation current is the same when the excitation current is high and when the excitation current is low, the current supply circuit to the CNG injector 47 is not complicated.

  When the CNG injector 47 is driven by voltage control, the high and low excitation voltages differ depending on whether the holding voltage is high or low, and the over-excitation voltages are equal. .

  In FIG. 4, when a low excitation current is supplied at time t1, the CNG injector 47 is opened to the first valve opening rate at time t2. On the other hand, when a high excitation current is supplied at time t1, the CNG injector 47 is opened to the second valve opening rate at time t3.

  Further, in FIG. 4, when the fuel injection amount of the CNG injector 47 is made equal between when the excitation current is high and when it is low, the low current drive for supplying the low current to drive the CNG injector 47 is performed. The time is set longer than the high current driving time for driving the CNG injector 47 by supplying a high current. That is, the area of the region surrounded by the waveform of the injector valve opening rate is made equal when the current is low and when the current is high.

  In FIG. 4, the low current driving time during which the CNG injector 47 opens at the first valve opening rate when the exciting current is low is the period from time t2 to time t5. Further, the high current drive time during which the CNG injector 47 opens at the second valve opening rate when the exciting current is high is a period from time t3 to time t4.

  The ECU 100 according to the present embodiment controls the overexcitation current and the holding current by adjusting the duty ratio (Duty ratio) of the drive signal for the solenoid coil 66 of the CNG injector 47. Therefore, the duty ratio at the overexcitation current is larger than the duty ratio at the holding current.

  Next, the ECU 100 will be described. The ECU 100 includes a computer unit that includes a central processing unit (CPU), a random access memory (RAM), a read only memory (ROM), a flash memory, an input port, and an output port.

  A program for causing the computer unit to function as the ECU 100 is stored in the ROM of the ECU 100 together with various control constants, various maps, and the like. That is, in the ECU 100, the computer unit functions as the ECU 100 when the CPU executes a program stored in the ROM.

  Various sensors such as a crank angle sensor and an accelerator position sensor (not shown) are connected to the input port of the ECU 100. A CNG injector 47 and a gasoline injector 34 are connected to the output port of the ECU 100.

  The ECU 100 controls the driving of the CNG injector 47 or the gasoline injector 34 based on the operating state of the vehicle 1 such as the engine speed detected by the crank angle sensor and the accelerator opening detected by the accelerator position sensor.

  The ECU 100 stores an excitation current-valve opening rate correlation map (not shown). The excitation current-valve opening rate correlation map opens the CNG injector 47 at the first valve opening rate and the second valve opening rate. Values of a low current and a high current are determined as excitation currents to be valved.

  The ECU 100 reduces the excitation current to the solenoid coil 66 of the CNG injector 47 to a low current or increases it to a high current on the basis of the excitation current-valve opening rate correlation map. The CNG injector 47 is controlled to open at the valve rate.

  In this embodiment, the low current excitation current is the basic drive current (initial value), and the ECU 100 causes the CNG injector 47 to provide a low current as the basic drive current when the internal combustion engine 10 is in a predetermined basic operation state. Is supplied to the solenoid coil 66, and the CNG injector 47 is controlled to open at the first valve opening rate.

  Then, as will be described later, the ECU 100 supplies a high excitation current to the CNG injector 47 when the required injection amount is larger than a predetermined threshold value or when the fuel feedback correction amount is equal to or larger than the predetermined threshold value. The CNG injector 47 is controlled to open at the second valve opening rate.

  Therefore, when the CNG injector 47 is driven at a first valve opening rate with a low current, the injection time is set longer than when it is driven at a second valve opening rate with a high current. On the contrary, when the CNG injector 47 is driven at a second valve opening rate with a high current, the injection time is set shorter than when it is driven at a first valve opening rate with a low current.

  When the CNG injector 47 is driven at the first valve opening rate, the fuel can be injected more stably even when the required injection amount is smaller than when driven at the second valve opening rate. Since the injection of a certain CNG becomes gentle, the inhalation of air is not hindered and mixing with air is performed well.

  Next, the flow of the high flow rate determination process executed by the ECU 100 according to the present embodiment will be described with reference to FIG. The high flow rate determination process is a process for performing fuel injection by switching the valve opening rate of the CNG injector 47 from the first valve opening rate to the second valve opening rate when the required injection amount is large. This high flow rate determination process is repeatedly executed at predetermined time intervals.

  As shown in FIG. 5, the ECU 100 first calculates a basic injection time (step S1). Here, ECU 100 calculates the basic injection time based on the air amount measured by an air flow sensor (not shown).

  Next, the ECU 100 determines whether or not the basic injection time is equal to or greater than a predetermined threshold (step S2). The threshold value used in step S2 is set to a value that prevents the CNG injector 47 from always opening when the CNG injector 47 is driven at the first valve opening rate by the low current that is the basic drive current. The The case where the basic injection time is equal to or greater than the predetermined threshold is a case where the required injection amount is equal to or greater than the predetermined injection amount because the engine load is large.

  When it is determined in step S2 that the basic injection time is less than the predetermined threshold, the ECU 100 maintains the basic drive current (step S3). Here, the ECU 100 maintains the excitation current to the CNG injector 47 at a low current that is a basic drive current. Thus, the CNG injector 47 is driven at the first valve opening rate by being supplied with a low current as an exciting current.

  Thereafter, the ECU 100 calculates the actual injection time according to the low current that is the basic drive current (step S4), and ends one routine of this high flow rate determination process.

  On the other hand, when it is determined in step S2 that the basic injection time is equal to or greater than the predetermined threshold, ECU 100 increases the excitation current to a high current (step S5). As a result, the CNG injector 47 is driven at the second valve opening rate when a high current is supplied as an exciting current.

  Thereafter, the ECU 100 calculates the actual injection time in accordance with the high current (step S6), and ends one routine of this high flow rate determination process. When the second valve opening rate is 100% and the first valve opening rate is 50%, the actual injection time calculated in step S6 is 50% of the actual injection time calculated in step S4. It will be time.

  According to this high flow rate determination process, in the operation region where the engine load is small such that the basic injection time is less than a predetermined threshold, the CNG injector 47 is driven at the first valve opening rate, thereby causing a relatively weak injection. Therefore, air inhalation is not hindered by strong CNG injection, and CNG and air are mixed well. Further, by driving the CNG injector 47 at the first valve opening rate, power consumption for driving the CNG injector 47 is reduced, and fuel efficiency is improved.

  Further, in an operating region where the engine load is large such that the basic injection time is equal to or greater than a predetermined threshold, the CNG injector 47 can be driven at the second valve opening rate to increase the injection amount per unit time. The amount is satisfied.

  Next, a flow of the fuel composition adjustment determination process executed by the ECU 100 according to the present embodiment will be described with reference to FIG. The fuel composition adjustment determination process is a process in which fuel injection is performed by switching the valve opening rate of the injector between the first valve opening rate and the second valve opening rate in accordance with the fuel composition of CNG. The fuel composition adjustment determination process is executed every time the internal combustion engine 10 is started.

  As shown in FIG. 6, the ECU 100 first sets the excitation current to the CNG injector 47 to the basic drive current (step S11). That is, ECU 100 sets the excitation current to a low current that is a basic drive current.

  Next, the ECU 100 determines whether or not the fuel feedback correction amount is greater than or equal to a predetermined threshold value (step S12). Here, the fuel feedback correction amount is a correction amount determined according to the composition of CNG. For example, when CNG with a small amount of methane as the main component is used, the fuel feedback correction amount increases. The predetermined threshold value in step S12 corresponds to a correction limit value for fuel feedback correction.

  When it is determined in step S12 that the fuel feedback correction amount is less than the predetermined threshold value, the ECU 100 executes step S12 again. Therefore, the ECU 100 maintains the excitation current to the CNG injector 47 at a low current that is a basic drive current.

  On the other hand, when it is determined in step S12 that the fuel feedback correction amount is equal to or greater than the predetermined threshold, the ECU 100 increases the excitation current to the CNG injector 47 to a high current (step S13), and then according to the high current. The actual injection time is calculated (step S14). Thereafter, the ECU 100 ends the fuel composition adjustment determination process.

  Thus, according to the fuel composition adjustment determination process, the ECU 100 drives the CNG injector 47 at the second valve opening rate when the fuel feedback correction amount is equal to or greater than the predetermined threshold value. Since the CNG injector 47 is driven at the second valve opening rate, the injection amount per unit time can be increased, so that the required injection amount after application of the fuel feedback correction is satisfied.

  When the fuel feedback correction amount is less than the predetermined threshold value, the CNG injector 47 is driven at the first valve opening rate. In this case, since the relatively weak injection is performed in the same manner as when the CNG injector 47 is driven at the first valve opening rate in the high flow rate determination process, the intake of air is inhibited by the strong injection of CNG. The mixing of CNG and air is performed well. Further, by driving the CNG injector 47 at the first valve opening rate, power consumption for driving the CNG injector 47 is reduced, and fuel efficiency is improved.

  Since the fuel composition does not change during operation of the internal combustion engine 10, if it is determined in step S12 that the fuel feedback correction amount is greater than or equal to a predetermined threshold value, the CNG injector 47 during operation of the internal combustion engine 10 will be described. The excitation current to is maintained at a high current.

  As described above, in the fuel injection device according to the present embodiment, the CNG injector 47 has the first elastic portion 67A having the first elastic force and the second elastic force larger than the first elastic force. A spring 67 comprising two elastic portions 67B and a solenoid coil 66 for compressing the spring 67 to the valve opening side, and the first elastic portion 67A is compressed to open at a first valve opening rate. Further, the second elastic portion 67B is compressed, so that the valve is opened at a second valve opening rate larger than the first valve opening rate.

  In addition, the ECU 100 controls the CNG injector 47 to open at the first valve opening rate or the second valve opening rate by increasing or decreasing the exciting current or exciting voltage to the solenoid coil 66.

  With this configuration, the excitation current or excitation voltage to the solenoid coil 66 can be increased or decreased to open the CNG injector 47 with high accuracy at the first valve opening rate or the second valve opening rate. For this reason, the dynamic range can be expanded.

  Furthermore, when the CNG injector 47 is driven at the first valve opening rate, a relatively weak injection is performed, so that the strong CNG injection does not hinder the inhalation of air, and the mixture of CNG and air Is done well.

  Further, by driving the CNG injector 47 at the first valve opening rate, power consumption for driving the CNG injector 47 is reduced, and fuel efficiency is improved. Further, in the operation region where the required injection amount becomes the predetermined fuel injection amount, the injection amount per unit time can be increased by driving the CNG injector 47 at the second valve opening rate, so that the required injection amount is satisfied. be able to.

  Also, when opening the CNG injector 47 to the first valve opening rate, the valve opening state can be opened from the closed state to the first valve opening rate in a shorter time than when opening to the second valve opening rate. Can be improved.

  In the fuel injection device according to the present embodiment, the second valve opening rate of the CNG injector 47 is 100%.

  With this configuration, the maximum injection amount set in the CNG injector 47 can be used, so that the dynamic range can be further expanded.

  Further, in the fuel injection device according to the present embodiment, the ECU 100 controls the CNG injector 47 so that the valve opens at the first valve opening rate or the second valve opening rate according to the fuel composition of the fuel.

  With this configuration, even when a fuel having a wide range of fuel composition is used, the internal combustion engine 10 can be operated satisfactorily for all fuel compositions.

  In the fuel injection device according to the present embodiment, when the required injection amount of the internal combustion engine 10 is equal to or greater than the predetermined injection amount, the ECU 100 controls the CNG injector 47 to open at the second valve opening rate. When the injection amount is less than the predetermined injection amount, the CNG injector 47 is controlled to open at the first valve opening rate.

  With this configuration, the internal combustion engine can be operated satisfactorily in the range of all required injection amounts.

  Further, in the fuel injection device according to the present embodiment, the ECU 100 increases or decreases the holding current or holding voltage for holding the valve open state of the CNG injector 47 out of the exciting current or exciting voltage to the solenoid coil 66. Thus, the CNG injector 47 is controlled to open at the first valve opening rate or the second valve opening rate.

  With this configuration, since the overexcitation current is the same when the excitation current is high and low, it is possible to avoid complication of the current supply circuit to the CNG injector 47.

  While embodiments of the present invention have been disclosed as described above, it will be apparent to those skilled in the art that changes may be made without departing from the scope of the invention. All such modifications and equivalents are intended to be included in the following claims.

  For example, the dynamic range of the gasoline injector 34 can be expanded by using the spring 67 shown in FIG. 3 for the gasoline injector 34 and switching the excitation current to the gasoline injector 34 to a high current or a low current.

  In the above-described embodiment, the low drive current is the basic drive current, but the high current may be the basic drive current. That is, a state in which the CNG injector 47 or the gasoline injector 34 is opened at a second valve opening rate due to a high current is set as a basic operation state of the internal combustion engine 10, and these injectors are operated at a low current according to the operation state. Switching may be performed so that the valve is opened at one valve opening rate.

DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 47 ... CNG injector (injector), 66 ... Solenoid coil, 67 ... Spring, 67A ... 1st elastic part, 67B ... 2nd elastic part, 100 ... ECU (control unit)

Claims (5)

In a fuel injection device comprising: an injector that injects fuel into an internal combustion engine; and a control unit that controls driving of the injector;
The injector is
A spring composed of a first elastic part having a first elastic force and a second elastic part having a second elastic force larger than the first elastic force;
A solenoid coil for compressing the spring to the valve opening side,
The first elastic portion is compressed to open at a first valve opening rate, and the second elastic portion is further compressed to open at a second valve opening rate greater than the first valve opening rate,
The fuel is characterized in that the controller controls the injector to open at the first valve opening rate or the second valve opening rate by increasing or decreasing an exciting current or exciting voltage to the solenoid coil. Injection device.   2. The fuel injection device according to claim 1, wherein the second valve opening rate of the injector is 100%.   The said control part controls the said injector to open at the said 1st valve opening rate or the said 2nd valve opening rate according to the fuel composition of a fuel, The Claim 1 or Claim 2 characterized by the above-mentioned. Fuel injectors. When the required injection amount of the internal combustion engine is equal to or greater than a predetermined injection amount, the control unit controls the injector to open at the second valve opening rate,
The fuel according to any one of claims 1 to 3, wherein when the required injection amount is less than a predetermined injection amount, the injector is controlled to open at the first valve opening rate. Injection device. The control unit increases or decreases the holding current or holding voltage for holding the valve opening state of the injector among the exciting current or the exciting voltage to the solenoid coil, so that the first valve opening rate or the second valve opening rate is increased. The fuel injection device according to any one of claims 1 to 4, wherein the injector is controlled to open at a valve opening rate.

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