JP2906622B2 - Injector drive circuit - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit for driving an injector (fuel injection device) for supplying fuel to an internal combustion engine.

2. Description of the Related Art An injector that supplies fuel to an internal combustion engine includes a valve that opens and closes a fuel injection port and an electromagnet that drives the valve, and is attached to an intake manifold or the like of the internal combustion engine. Fuel is supplied to the injector from the fuel pump at a predetermined pressure, and when a drive current is applied to the excitation coil of the electromagnet, the valve is opened to inject the fuel.

A drive circuit for operating the injector (opening a valve of the injector) includes an injector drive switch for turning on and off a drive current supplied from a power supply to the excitation coil, and the switch is turned on when a fuel injection command is given. The fuel is injected by exciting the exciting coil.

In a conventional injector drive circuit, a battery is used as a power supply. However, recently, it has been considered to drive an injector with an output of a generator driven by an internal combustion engine.

FIG. 12 is a circuit which is normally considered when a driving current is supplied to the exciting coil 2 of the injector with the output obtained from the power generating coil 1 in the AC generator driven by the internal combustion engine.
In this example, the injector driving switch 3 is composed of a transistor TR1, and a collector-emitter circuit of the transistor TR1 is connected in series to the exciting coil 2. A diode 4 is connected in series to the generating coil 1, and an exciting coil 2 is connected to both ends of a series circuit of the generating coil 1 and the diode 4.
And an injector driving switch 3 are connected in series.

In the drive circuit of FIG. 12, while a fuel injection command is given, a transistor TR1
Is supplied with a base current (trigger signal). While the base current is being supplied, the transistor TR1 is turned on to supply a drive current to the exciting coil 2. The injector operates (the valve opens) and fuel is injected only while the drive current of a predetermined level or more is being supplied.

The configuration shown in FIG. 12 corresponds to a conventional driving circuit using a battery as a power source, in which the battery is replaced with a series circuit of a power generating coil 1 and a diode 4.

In the injector drive circuit powered by a battery,
It is desirable that a driving current I having a waveform as shown in FIG. 4 be supplied to the injector.

That is, at time t1, when the injector driving switch (corresponding to the transistor 3 in FIG. 12) is triggered and becomes conductive, the driving current I starts to flow through the exciting coil 2. Due to the inductance of the exciting coil 2, the rise of the drive current I is delayed. At time ton, the drive current I becomes the operation start current value Io
When it reaches n, the operation of the injector is started. When the valve of the injector opens, the increase in the drive current is temporarily suppressed by the change in the inductance of the exciting coil, but thereafter the drive current increases again. After the drive current reaches a predetermined peak value, the drive current I is decreased to reduce the drive current I to a value Id (sufficiently smaller than Ion) required to keep the injector valve open. And prevent unnecessary power consumption. At time t2, when the injector drive switch is turned off (supply of the fuel injection command signal is stopped), the value becomes zero.

Even when a generator is used as the power source as shown in Fig. 12,
By appropriately controlling the base current of the transistor 3, for example, a sufficiently large base current is applied to the transistor 3 at time t1 when the fuel injection command signal is applied, and when the drive current I reaches a predetermined peak value Ip, By controlling the base current to decrease stepwise, the fourth
A drive current I having a waveform similar to that shown in FIG.

[Problem to be Solved by the Invention] In FIG. 12, when the power generation capacity of the power generation coil 1 is small, the drive current cannot reach the operation start current value Ion unless the rotation speed of the engine becomes high. Therefore, in order to start the engine without any trouble, the power generation capacity of the power generation coil 1 needs to be sufficiently large, and there is a problem that the power generation coil becomes large.

If the injector is not used for a long time, the fuel inside the injector will evaporate, and the remaining contaminants will adhere to the operating part of the injector and oxidize olefin hydrocarbons (CnH2n) contained in the fuel. As a result, the sticky glue generated by the process adheres to the movable part of the injector, so that the sliding resistance of the movable part of the injector increases and the valve of the injector becomes difficult to open.

In this case, in order to overcome the sliding resistance of the movable part and operate the injector, it is necessary to supply a large drive current to the exciting coil. However, if the internal resistance of the power supply (power generation coil) is large, the sliding resistance is reduced. However, there is a problem that it is not possible to secure a drive current necessary to overcome the above problem.

As can be seen in Japanese Patent Publication No. 50-25092, a capacitor is connected in series with the exciting coil of the injector, and the capacitor is excited between the output terminals of the rectifier that rectifies the output of the generator driven by the engine. There is known an injector drive circuit in which a series circuit with a coil is connected in parallel and an injector drive switch is connected in parallel with the series circuit with the capacitor and the exciting coil.

However, in such a configuration, since the charging current of the capacitor flows through the driving coil of the injector, the injector may malfunction due to the charging current of the capacitor, which is not preferable.

In the case of the configuration shown in Japanese Patent Publication No. 50-25092, the energy supplied to the exciting coil of the injector is only the energy stored in the capacitor.
When it is necessary to extend the fuel injection time, such as when starting the engine in a low temperature state, it is necessary to use a large-capacity capacitor as a capacitor. And the costs are inevitable.

In the case of the configuration shown in Japanese Patent Publication No. 50-25092, when the injector drive switch is turned on,
Since the generator is completely short-circuited through the switch, a large short-circuit current flows through the injector driving switch. For this reason, it is necessary to use a switch having a large current capacity as the injector driving switch, which inevitably increases the cost.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an injector drive circuit that supplies a drive current to an excitation coil of an injector for an internal combustion engine when a fuel injection command is given to open a valve of the injector. An object of the present invention is to enable the injector to be driven without any trouble even when a power generating coil having a large resistance is used as a power supply.

[Means for Solving the Problems] In the present invention, a generator coil provided in an AC generator driven by an internal combustion engine, a rectifier for rectifying an output voltage of the generator coil, and an output terminal of the rectifier are provided. A peak current generating capacitor connected in parallel and charged with the output voltage of the rectifier; and an injector drive switch connected in series with the exciting coil and closed when a fuel injection command signal is given. A series circuit of the injector driving switch and the exciting coil is connected in parallel to the capacitor.

[Operation] As described above, the peak current generating capacitor charged by the rectified output of the power generation coil provided in the AC generator driven by the internal combustion engine is provided, and is closed when a fuel injection command signal is given. When the injector driving switch is connected in series to the exciting coil and the series circuit of the switch and the exciting coil is connected in parallel to the capacitor, the period during which the switch is shut off (injector idle period) Since the energy is stored in the capacitor by the output of the power supply, when the fuel injection command is given and the switch is turned on, the energy stored in the capacitor is released and the drive current flows through the exciting coil. The maximum value of the drive current can be made larger than when no capacitor is provided. Therefore, even if the power generation capacity of the power generation coil is low or the internal resistance of the power generation coil is large, a large drive current can be supplied to the excitation coil of the injector.

As described above, when a peak current generating capacitor is connected in parallel between the output terminals of the rectifier, and a series circuit of the injector driving switch and the injector exciting coil is connected in parallel to the capacitor, the peak current generating capacitor is connected. Since charging current does not flow through the exciting coil of the injector when charging the capacitor, malfunction of the injector can be prevented.

In addition, in the case of the above configuration, the peak current generating capacitor only needs to be able to flow the peak current, and the excitation current after the peak current flows is supplied from the generator. A small-sized and small-capacity current generating capacitor can be used.

Further, in the case of the above configuration, since the peak current generating capacitor and the exciting coil of the injector become loads of the generator when the injector driving switch is turned on, the current flows when the injector driving switch is closed. The current can be smaller than the short-circuit current of the generator. Therefore, an injector driving switch can be configured using a switch element having a smaller current capacity than a conventional injector driving circuit in which a capacitor is connected in series with the exciting coil of the injector.

Embodiment An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a generator coil for driving an injector provided in a magnet type AC generator driven by an internal combustion period, 2 denotes an excitation coil of the injector, 3 Is an injector driving switch composed of an NPN transistor TR1. In the present invention, a peak current generating capacitor 5 is connected in parallel to a series circuit of the power generating coil 1 and the diode 4, and a series circuit of the exciting coil 2 and the switch 3 is connected in parallel to the capacitor 5. ing.

Fig. 5 shows the maximum output current of the maximum output voltage Vm of the generator coil 1 when the rotational speed of the magnet type alternator is No (rpm).
The curve (a) and the curve (b) show the characteristics of the generating coil A having a small number of turns, respectively.
In this case, a large-sized power generating coil B having a large number of turns and a large wire diameter is used. Here, Vm is an amplitude v = Vm sin (ωt + θ) when the waveform of the output voltage of the power generation coil is a sine wave.
This is the maximum value Vm of 1). Similarly, Im is the amplitude i = Im sin when the waveform of the output current of the power generation coil is a sine wave.
This is the maximum value Im of (ωt + θ2).

In FIG. 5, the straight line Rij indicates that the internal resistance R of the exciting coil is R
This is a load straight line when the injector of ₀ is used, and the intersection of the load straight line and the curves a and b is the operating point at the rotation speed No when the generating coils A and B are used, respectively.

The current that needs to flow through the excitation coil to operate the injector (opens the injector valve) is defined as the operation start current Ion, and the output voltage of the generating coil required to flow this operation start current Ion is defined as the operation start voltage Von. Then
In the drive circuit shown in FIG. 12, the point at which the injector starts operating is point P. That is, if the rotation speed is No,
If the power generating coil A having a small number of turns is used, the injector cannot be operated.

FIG. 7 shows the power generation coil A when the rotation speed is set to No.
7 shows Vm-Im characteristics together with a load straight line of an injector. In order for the circuit of FIG. 12 to operate the injector using the power generating coil A, it is necessary to set the rotation speed to N3 or more as shown in FIG.

In FIG. 5, the operating point when the generating coil A is used is Q, and the generated voltage (sine wave) at that time is Vo, the maximum value of the current flowing through the injector at the operating point Q.
Imax is given by the following equation.

Imax = Vo / X (1) where X = ｛(Ro + R1) ² + ω ² (Lo + L1) ² ｝ ^1/2 (2) where Ro and R1 are the resistances of the injector and the generating coil, respectively, and Lo and L1 are These are the inductances of the injector and the generator coil, respectively. When voltage v is half-wave rectified or full-wave rectified, Imax becomes smaller than the value given by equations (1) and (2).

In the embodiment shown in FIG. 1, the power generation coil A (curve a) shown in FIG. 5 is used as the power generation coil 1, and the number of revolutions of the generator is No.

Assuming that the transistor TR1 is in the cutoff state, the peak current generating capacitor 5 is charged to the no-load voltage Von. When the transistor TR1 is turned on, the electric charge stored in the capacitor 5 is discharged through the exciting coil 2 of the injector. This discharge current becomes the drive current for the ejector, and the amount of current can be obtained from the equivalent circuit shown in FIG.

In FIG. 9, C is the capacitance of the capacitor 5, R2 is the resistance of the circuit other than the exciting coil 2, and SW is the transistor TR1.
Is a switch corresponding to.

Assuming that the switch SW is closed at time t = 0 and the terminal voltage of the capacitor 5 at that time is Von, the current i flowing through the exciting coil is obtained by the following equation.

(I) (Ro + R2) ² > 4Lo / C i = (Vno / Loβ) e− ^αt sinhβt (3) where α = (Ro + R2) / (2Lo) (4) β = [｛(Ro + R2) ^{2 -4Lo / C} 1/2] /} (2Lo) ... (5) (II) (Ro + R2) 2 = for 4Lo / C i = (Vno / Lo) te -αt ... (6) (III) (Ro + R2 ) ² <4Lo / C i = {Vn0 / (Lo · γ)｝ sin (γt) e− ^αt (7) γ = {(1 / CLo) − (Ro + R2) ² / (2Lo) 2} ^{1 / 2} (8) As is apparent from the above equation, the current i is proportional to the terminal voltage Vno of the capacitor 5.

Further, the current i in the equations (3), (6), and (7) takes a peak value Ip at the following time t.

(I) When (Ro + R2) ² > 4Lo / C Ip = (Vno / Loβ) e− ^αt sinhβt (3 ′) t = 1n (1 + β) / {2β (1-β)} (9) (II) ) (Ro + R2) ² = 4Lo / C Ip = (Vno / Lo) te ^-αt (6 ′) t = (1 / α) (10) (III) (Ro + R2) ² <4Lo / C Ip = ｛Vno / (Lo · γ)｝ sin (γt) e− ^αt (7 ′) t = (1 / γ) tan ⁻¹ (γ / α) (11) From the above equations, the present invention The peak value Ip
The conditions under which the current value becomes larger than the maximum current value Imax in the case of the conventional driving circuit are as follows.

(I) (Ro + R2) ² > 4Lo / C Vno / Vo> Loβ / ｛e− ^αt sinh (βt)｝ X (12) (II) (Ro + R2) ² = 4Lo / C Vno / Vo> Lo / te− ^αt X (13) (III) (Ro + R2) ² <4Lo / C Vno / Vo> Loγ / [｛sin (γt) e- ^αt ｝ X] (14) It can be seen that when Vno / Vo is greater than a certain value that is uniquely determined, Ip> Imax.

Load resistance R is Ro (in case of injector), Ro1, and Ro2
When the load straight line of (Ro <Ro1 <Ro2) is superimposed on the Vm-Im characteristic curve of the generating coil A of the magnet generator and shown in FIG. 6, the load resistance changes as Ro → Ro1 → Ro2. Then, the operating point changes as follows: Q → Q ′ → Q ″. When the load resistance is infinite (when no load is applied), the load line coincides with the vertical axis. Operating points Q, Q ′ and Q ″ The generated voltage at
o, Vo ′ and Vo ″, the ratio between the no-load voltage and the voltage generated at each operating point is (Vno / Vo)> (Vno / Vo ′)> (Vn
o / Vo ″).

Generally, the resistance of the injector is as small as about 1 Ω to several tens of Ω, and the load is high for the power generation coil. Therefore, the load straight line of the injector is located near the horizontal axis as shown in FIG. Therefore, when the magnet type alternator is used, the condition for Vno >> Vo and the condition of Ip> Imax can be easily satisfied.

That is, as in the drive circuit of the present invention, when the capacitor 5 is added, when the above condition is satisfied, Ip> Imax, and when Ip> Ion, the injector is driven by the power generation coil A at the rotation speed No. be able to. Therefore, according to the present invention, the injector can be driven even if the power generation coil A having a low power generation capacity that cannot alone flow the operation start current Ion is used.

In the case where the power generating coil A is used in the circuit shown in FIG. 12, the operation start current Ion cannot flow unless the number of rotations reaches N3 or more as shown in FIG. In the case of a circuit, although Ip> Imax at the rotation speed No, the operation start current Ion can flow at a rotation speed lower than the rotation speed N3 even if Ip ≦ Ion.

Therefore, according to the present invention, the operation of the injector can be started at a lower rotational speed than in the related art.

Also, assuming that the rotation speed of the generator is the same, Ip> Imax
Then, the driving force of the injector when the current Ip flows is naturally larger than the driving force when the current Imax flows. Therefore, even when the sliding resistance of the injector has increased because the injector has not been used for a long time,
Driving of the injector can be enabled.

As described above, when the peak current generating capacitor 5 is connected in parallel between the output terminals of the rectifier and the series circuit of the injector driving switch 3 and the exciting coil 2 of the injector is connected in parallel to the capacitor 5, Since the charging current does not flow through the exciting coil of the injector when charging the current generating capacitor, malfunction of the injector can be prevented.

Also, with the above configuration, the peak current generating capacitor 5 only needs to be able to pass the peak current, and the excitation current after the peak current flows is supplied from the power generation coil 1. As the current generating capacitor 5, a capacitor having a small size and a small capacity can be used.

Further, in the case of the above configuration, when the injector driving switch 3 is turned on, the peak current generating capacitor 5 and the exciting coil 2 of the injector load the generator, so that the injector driving switch 3 is closed. The current that flows when this occurs can be made smaller than the short circuit current of the generator. Therefore, the capacitor was connected in series with the exciting coil of the injector.
-25092), it is possible to configure the injector driving switch 3 using a switch element having a smaller current capacity.

In the embodiment shown in FIG. 1, the output of the power generating coil 1 is half-wave rectified and supplied to the capacitor 5, but the output of the power generating coil 1 is passed through the full-wave rectifier 6 as shown in FIG. The power may be supplied to the capacitor 5.

Furthermore, in order to obtain a larger peak current Ip, the power generation coil can be configured in three phases, or a plurality of power generation coils can be used.

In the circuit shown in FIG. 1, when Ro + R2 = R, and the number of turns and the number of revolutions of the power generating coil are n and N, respectively, the terminal voltage Vc of the capacitor 5 is obtained as follows.

^{Vc = (K1 / C 1/2)} {δ / (δ 2 -1)} × [δsin {2π / (δ + 1)} - sin {2πδ /
(Γ + 1)｝ (15) where δ = K2 (C ^1/2 ) n · N (16) K1 and K2 are constants determined by the magnetic circuit of the magnet-type alternator. It is constant if it falls. (15)
From the equation, if the electrostatic characteristic C of the capacitor 5 is determined, the terminal voltage Vc of the capacitor 5 becomes a function of only nN. FIG. 10 shows the relationship between nN and Vc, where Vc is maximum when nN = noNo. Therefore, when only one generator coil having no winding number is used, when the rotation speed is No, the terminal voltage Vc of the capacitor 5 becomes maximum, and when the rotation speed becomes larger or smaller than No, , The voltage Vc decreases.

If the number of turns of the generating coil is selected to be small, the capacitor 5
Since the rotation speed at which the terminal voltage Vc becomes the maximum increases, the voltage Von necessary to flow the operation start current Ion in a region where the rotation speed is large can be obtained. Since the number of rotations at which the terminal voltage Vc becomes maximum decreases, it is possible to obtain a voltage Von necessary to flow the operation start current Ion in a region where the number of rotations is small.

Therefore, as shown in FIG. 3, a power generating coil 1A having n1 turns and a power generating coil 1B having n2 turns (> n1) are provided, and outputs of these power generating coils are applied to the capacitor 5 via diodes 4A and 4B, respectively. When the number of turns n1 and n2 is set appropriately, a sufficient drive current can be supplied to the injector in the entire rotational speed range of the engine, and the injector can be operated satisfactorily.

The curve a in FIG. 11 shows the terminal voltage Vc of the capacitor 5 when the power generating coil 1A having a relatively small number of turns n1 is used alone.
With respect to the rotation speed N. A curve b shows the terminal voltage Vc of the capacitor 5 with respect to the rotation speed N when the power generation coil 1B having a relatively large number of turns n2 is used alone. When the generator coil 1A is used alone (in the case of the curve a), the terminal voltage Vc of the capacitor increases in a region where the rotation speed is high, and the terminal voltage reaches Von at the rotation speed N1 and the injector starts operating. . Also a generator coil
When 1B is used alone (in the case of the curve b), the terminal voltage increases in a region where the rotation speed is low, and the voltage Vc reaches the operation start voltage Von of the injector at the rotation speed No (<N1). In a region exceeding N2 (> N1), the voltage Vc becomes lower than the operation start voltage Von of the injector. When a driving circuit as shown in FIG. 3 is constituted by using these power generating coils 1A and 1B together, the rotation speed N of the terminal voltage Vc of the capacitor 5 is obtained.
Is as shown by the curve c in FIG.
In all of the above regions, the injector operation start voltage Von
By obtaining the above voltage, the injector can be operated satisfactorily. By appropriately setting the number of turns n1 of the generator coil 1A, the operation start rotation speed No of the injector can be set sufficiently low.

Also in the configuration of FIG. 3, a full-wave rectifier can be used as a rectifier for rectifying the output of the power generation coil.

Although two power generating coils are used in the embodiment shown in FIG. 3, more power generating coils can be used. In general, it is possible to adopt a configuration in which n power generating coils having different numbers of turns are used, and the outputs of the n power generating coils are rectified and applied to a capacitor.

In the above description, a magnet-type AC generator is used as a generator, but another AC generator may be used.

[Effects of the Invention] As described above, according to the present invention, a peak current generating capacitor that is charged by a rectified output of a power generation coil provided in an AC generator driven by an internal combustion engine is provided, and a fuel injection command is provided. An injector drive switch that closes when a signal is applied is connected in series to the exciting coil, and a series circuit of the switch and the exciting coil is connected in parallel to the capacitor. Even if the power generation capacity is low or the internal resistance of the power generation coil is large, a large drive current can flow through the excitation coil of the injector. Therefore, even if a generator having a relatively low power generation capacity is used, it is possible to easily start the engine by lowering the operation start rotation speed of the injector, and to move the injector after leaving the injector unused for a long period of time. The injector can be operated even when the sliding resistance of the section is high.

In addition, since a small-sized one can be used as the generator coil for driving the injector provided in the generator, the space occupied by the generator coil for driving the injector in the generator can be reduced, and the space for arranging the other generator coils can be reduced accordingly. Can be increased.

Further, according to the present invention, an injector drive circuit can be realized with a simple configuration including a power generating coil, a rectifier for rectifying the output of the power generating coil, and a capacitor charged by the output of the rectifier. Cost can be reduced.

Further, according to the present invention, the injector can be driven by using the AC generator driven by the internal combustion engine as a power source, so that the injector can be driven even when the battery in which the internal combustion engine is mounted is not provided. There is.

Furthermore, according to the present invention, the peak current generating capacitor is connected in parallel between the output terminals of the rectifier, and the series circuit of the injector driving switch and the injector exciting coil is connected in parallel to the capacitor, so that the peak current When charging the generation capacitor, charging current is prevented from flowing through the exciting coil of the injector, so that malfunction of the injector can be prevented.

Further, according to the present invention, the peak current generating capacitor only needs to be capable of flowing only the peak current,
Since the exciting current after the peak current flows is supplied from the power generation coil, the cost can be reduced by using a small and small-capacity peak current generating capacitor.

Further, in the present invention, the current flowing when the injector drive switch is closed is generated by the power supply when the injector drive switch is closed, so that the peak current generating capacitor and the injector excitation coil become loads on the generator when the injector drive switch is turned on. Can be limited to a value smaller than the short circuit current of the machine. Therefore, compared to the conventional injector drive circuit in which a capacitor is connected in series to the injector excitation coil, it is possible to reduce the cost by configuring the injector drive switch using a switch element having a smaller current capacity. it can.

[Brief description of the drawings]

1 to 3 are circuit diagrams each showing a main part of a different embodiment of the present invention. FIG. 4 is a diagram showing a drive current waveform of an injector and an operation of a switch of a drive circuit.
The figure shows the characteristic of the generator coil with different number of turns and the load straight line, with the rotation speed as a constant value No. FIG. 6 shows the case where the resistance of the load connected to the generator coil of the magnet type generator is changed. FIG. 7 is a diagram showing the characteristics of the generator and the load straight line at various rotation speeds, FIG. 8 is a diagram showing the characteristics of the battery and the load straight line, FIG. 9 shows the first
FIG. 10 is a circuit diagram showing an equivalent circuit of the embodiment of the figure, and FIG. 10 shows a change in capacitor terminal voltage with respect to the product of the number of turns of the magnet generator and the number of turns of the generator coil when a single generator coil is used. FIG. 11 is a diagram showing the terminal voltage of the capacitor with respect to the rotation speed N when the power generating coils having different numbers of turns are used alone and when two power generating coils having different numbers of turns are used together. FIG. 12 is a circuit diagram showing an injector drive circuit in which a power generation coil is used as a power source, following the configuration of a conventional drive circuit using a battery as a power source. 1 ... power generating coil, 2 ... exciting coil of injector,
3 ... switch, 4 ... diode (rectifier), 5 ...
Capacitor for peak current generation, 6 Full-wave rectifier, 1A, 1
B: Generating coils with different number of turns, 4A, 4B: Diode.

Continuing from the front page (72) Inventor Tsuneaki Endo 3744 Ooka, Numazu, Shizuoka Prefecture Inside Domestic Electric Corporation (72) Inventor Ryuji Satsukawa 3744, Ooka, Numazu City, Shizuoka Prefecture Inside Domestic Electric Corporation (56) Reference Document JP-A-2-186178 (JP, A) JP-A-2-176139 (JP, A) JP-A-63-259129 (JP, A) JP-A-58-13133 (JP, A) 185650 (JP, A) Japanese Utility Model Showa 61-118944 (JP, U) Japanese Patent Publication No. 50-25092 (JP, B2) Japanese Patent Publication No. 49-15167 (JP, B1) Japanese Patent Publication No. 49-45248 (JP, B1) (58) Fields surveyed (Int.Cl. ⁶ , DB name) F02D 41/20 F02D 29/06 F16K 31/06

Claims (1)

(57) [Claims] 1. An injector drive circuit for supplying a drive current to an exciting coil of an injector for an internal combustion engine when a fuel injection command is given to open a valve of the injector, provided in an AC generator driven by the internal combustion engine. The power generating coil, a rectifier for rectifying the output voltage of the power generating coil, a peak current generating capacitor connected in parallel between the output terminals of the rectifier and charged with the output voltage of the rectifier, and the exciting coil. An injector drive switch which is connected in series to the fuel injection command signal and is closed when the fuel injection command signal is given, wherein a series circuit of the injector drive switch and an exciting coil is connected in parallel to the capacitor. An injector drive circuit, comprising: