JP2002227698A - Fuel injection valve drive device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection valve drive device, it judges a short circuit and a disconnection in a fuel injection valve. SOLUTION: A fuel injection valve drive device possesses the electromagnet, and according to energizing to the electromagnet, become open the valve of fuel injection, it is prepared in this electromagnet in series, therein a current detection means to detect the current which flows on this electromagnet after predetermined time progress after starting the energization to this electromagnet, if the current detected by this current detection means exceeds the 1st threshold decided beforehand, it judges with the short circuit having occurred for the current course in a fuel injection valve, if the current detected by this current detection means is less than the 2nd threshold decided beforehand it provides with an abnormal judgment means which judges that the disconnection has been generated in the current route in the fuel injection valve. In this way, the short circuit and disconnection in a fuel injection valve can be judged with easy structure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection valve driving device, and more particularly, to a fuel injection valve driving device for detecting disconnection and short circuit in a fuel injection valve.

[0002]

2. Description of the Related Art Conventionally, in a fuel injection valve driving apparatus for an internal combustion engine, a valve operating mechanism using an electromagnetic actuator has been adopted. The electromagnetic actuator includes a needle (valve) that is urged in a valve closing direction by a spring, and a solenoid-type electromagnet in which the needle is disposed in close proximity. A movable member biased by a spring is connected to the needle. When power is supplied to the electromagnet, the movable member is attracted to the electromagnet and the needle is opened. When the power supply to the electromagnet is stopped, the movable member moves away from the electromagnet by the force of the spring, and the needle closes.

In such a fuel injector driving device,
There has been proposed a method for detecting disconnection and short circuit in a coil of an electromagnet and wiring to the coil. For example,
JP-A-64-64523 discloses a current sensing circuit for detecting a part of a current flowing through an electric load driving element.
A method is disclosed in which a current flowing through the sense circuit is compared with a predetermined value, and when the current flowing through the sense circuit exceeds a predetermined value, it is determined that an overcurrent is caused by a short circuit of an electric load.

Japanese Patent Application Laid-Open No. Hei 9-112735 discloses that a voltage across a capacitor immediately before turning on a transistor for energizing a coil of an electromagnet of a fuel injection valve is monitored. If not, a method of determining that some current path of the coil of the electromagnet is short-circuited, and determining that some current path of the coil of the electromagnet is disconnected if the voltage at both ends is not less than a predetermined value is disclosed. .

[0005]

However, according to the method disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 64-64523, it is necessary to newly provide a sense circuit, so that the number of wirings is increased, and detection is not possible. The abnormalities that can be performed are limited to overcurrent. Further, according to the method disclosed in the above-mentioned Japanese Patent Application Laid-Open No. Hei 9-112735, it is also determined that an abnormality occurs when a voltage drop abnormality occurs inside the circuit due to other causes. It cannot be determined whether the cause is a disconnection or a short circuit. Furthermore, according to this method, since the capacitor for abnormality determination is used in common for the fuel injection valve of each cylinder, all cylinders other than the cylinder in which abnormality has actually occurred can be operated when it is determined to be abnormal. Disappears.

On the other hand, in recent years, a direct injection type gasoline internal combustion engine has been proposed. In the direct injection type internal combustion engine, a fuel injection valve is provided at the center top of the combustion chamber, and pressurized fuel is directly injected from the fuel injection valve into the combustion chamber. Since the fuel injection valve is pushed by high-pressure fuel, when opening the fuel injection valve, for example, 150 V
Is applied to the fuel injection valve. Therefore, when a short circuit occurs in the fuel injection valve, the drive current flowing through the coil of the electromagnet of the fuel injection valve rises very quickly, and the coil (drive element) of the electromagnet in the fuel injection valve may be broken. Therefore, it is necessary to detect an overcurrent before the drive current reaches the maximum current allowed by the coil.

Therefore, not only an overcurrent due to a short circuit in the fuel injection valve, but also a disconnection in the fuel injection valve can be detected at the same time. Is needed.

[0008]

According to a first aspect of the present invention, there is provided a fuel injection valve driving device including an electromagnet;
A fuel injection valve that opens by energizing the electromagnet;
A current detecting means provided in series with the electromagnet, for detecting a current flowing through the electromagnet after a predetermined time has elapsed since the start of energization of the electromagnet; and a current detected by the current detecting means is predetermined. If the current value exceeds the first threshold value, it is determined that a short circuit has occurred in the current path in the fuel injection valve, and the current detected by the current detection means is set to a predetermined second threshold value. If it falls below
Abnormality determining means for determining that a disconnection has occurred in the current path of the fuel injection valve.

According to the first aspect of the present invention, disconnection and short circuit in the fuel injection valve are determined based on the current flowing through the electromagnet of the fuel injection valve. Therefore, both disconnection and short circuit in the fuel injection valve can be determined simultaneously. .

According to a second aspect of the present invention, in the fuel injection valve driving device of the first aspect, the current detecting means is a resistor connected in series to the electromagnet.

According to the second aspect of the present invention, the abnormality in the fuel injection valve is determined by detecting the current flowing through the resistor connected in series to the electromagnet. Therefore, the abnormality determination is performed by directly monitoring the current flowing through the load. Accuracy can be improved and abnormality can be determined with a small number of parts.

According to a third aspect of the present invention, in the fuel injection valve driving device according to the first aspect of the present invention, there is provided a power supply stopping means for stopping the power supply to the electromagnet if the abnormality determining means determines that the current is abnormal. Take.

According to the third aspect of the present invention, if it is determined that there is an abnormality, the energization of the electromagnet of the fuel injection valve that has been determined to be abnormal is stopped, so that only the fuel injection valve that has been determined to be abnormal is stopped. Therefore, even when an abnormality is determined, the vehicle can run on its own.

According to a fourth aspect of the present invention, in the fuel injector driving apparatus of the first aspect, the first threshold value and the second threshold value are set so as to be adapted to the characteristics of each fuel injector. It is configured to be performed.

According to the fourth aspect of the present invention, since the threshold value is set so as to be suitable for each fuel injection valve, the accuracy of abnormality determination for each fuel injection valve can be improved.

According to a fifth aspect of the present invention, in the fuel injection valve driving device according to the first aspect of the present invention, the current detected by the current detecting means is compared with predetermined first and second threshold values. The timing is set so as to be adapted to the characteristics of each fuel injection valve.

According to the fifth aspect of the present invention, the comparison timing is set so as to be suitable for each fuel injection valve, so that the accuracy of abnormality determination for each fuel injection valve can be improved.

According to a sixth aspect of the present invention, in the fuel injection valve driving device according to the first aspect of the invention, the fuel injection valve is mounted on an in-cylinder direct injection internal combustion engine.

According to the sixth aspect of the present invention, it is possible to determine an abnormality in the fuel injection valve of the direct injection type internal combustion engine. Therefore, even if a short circuit occurs in the fuel injection valve, the coil of the electromagnet can be broken. Therefore, the operation of the fuel injection valve can be stopped.

[0020]

FIG. 1 shows a fuel injection valve 1 provided in an internal combustion engine. The fuel injection valve 1 includes a housing 2 having a substantially cylindrical shape, and a cylindrical connecting portion 3 connected to a distal end portion of the housing 2 by caulking or the like. The connecting portion 3 is provided at its tip with an injection port 4 which faces the combustion chamber of the internal combustion engine and injects fuel into the combustion chamber, and a valve body 5 which opens and closes the injection port 4 is housed therein. I have. In the figure, reference numeral 6 is a swirl forming member that forms a swirl in the fuel when the valve is opened, and reference numeral 7 is an annular seal member having heat shielding properties.

An electromagnet actuator 8 is provided inside the housing 2. Electromagnet actuator 8
Has a coil 10 wound and supported on a cylindrical bobbin 9,
An electromagnet 12 including a cylindrical core 11 provided to be inserted into the coil 10 is provided. Further, the electromagnet actuator 8 includes a movable member 14 made of a magnetic material or a soft magnetic material attracted to the end face 13 of the core 11 of the electromagnet 12.

The movable member 14 is connected to the valve element 5 via a rod 15 and is urged away from the core 11 by a spring 16 built in the core 11. The rod 15 is provided so as to be able to move in the axial direction through a partition 17 provided between the housing 2 and the connection portion 3. Further, the rod 15 is provided with a regulating member 19 that regulates the movement of the rod 15 by abutting on the partition wall 17.

A fuel supply unit 22 having a filter 21 is provided at the rear end of the extension 20 which continuously extends rearward from the core 11.
Is provided. The fuel compressed and sent from the fuel supply unit 22 fills the distal end portion of the housing 2 through the fuel passage 23 inserted in the core 11 and the gap between the inner wall of the movable member 14 and the rod 15. At this time, seal members 24 and 25 are provided between the core 11 and the bobbin 9 and between the bobbin 9 and the inner wall of the housing 2 to prevent the filled high-pressure fuel from leaking to the outside. The power supply connector that supplies power to the coil 10 via the conductor 27 is indicated by reference numeral 26 in the figure. Power supply means (not shown) is connected to the power supply connector 26.

The core 11 is provided with a magnetic path forming portion 28 having an outer diameter larger than the outer diameter of the movable member 14, whereby a sufficient magnetic flux can be formed when the movable member 14 is attracted. Further, the end surface 13 of the core 11 has a tapered surface 29 whose diameter gradually decreases from the magnetic path forming portion 28 toward the distal end, and a distal end edge of the tapered surface 29 and the contact surface 30 of the movable member 14. Is formed. Like the contact surface of the movable member 14, the suction surface 31 has a taper angle θ of 4 based on a line perpendicular to the axis of the core 11.
Preferably, it is set to about 0 ° to 60 °.

The operation of the electromagnet actuator 8 in the fuel injection valve 1 will be briefly described. Electric power is supplied to the coil 10 via the power supply connector 26. In this power supply state, the contact surface 30 of the movable member 14 is
The fuel is injected from the injection port 4 with the valve body 5 separated from the seat surface.

When the power supply from the power supply connector 26 to the coil 10 is stopped, the movable member 14 moves away from the core 11 by the bias of the spring 16. Accordingly, the valve element provided at the tip of the rod 15 closes the fuel injection port 4. Thus, the fuel injection from the injection port 4 is stopped.

Thereafter, when power is supplied to the coil via the power supply connector 26, the movable member 14 moves toward the core 11 by the attraction of the electromagnet 12, and the movable member 14
Contact surface 30 of the core 11 is attracted to the attracting surface 31 of the core 11. At this time, as the movable member 14 moves, the valve body 5 separates from the injection port 4 via the rod 15, and the fuel in the connection portion 3 is injected from the injection port 4 into the fuel chamber at a high pressure.

FIG. 2 is a diagram schematically showing a fuel injection valve driving circuit applied to an in-cylinder direct injection type internal combustion engine according to an embodiment of the present invention. This drive circuit is provided for each fuel injection valve.

The high-voltage control circuit 31 is a circuit that boosts a 12-volt power supply voltage on a vehicle to, for example, 150 V. The voltage boosted by the high voltage control circuit 31 is stored in the capacitor C1.

The timing circuit 32 is a circuit for controlling the operation of each part of the fuel injection valve drive circuit based on a control signal from an engine ECU (electronic control unit) for controlling the operation of the engine. The drive control circuit 33 includes the timing circuit 3
In accordance with the control signal received from the ECU via the control unit 2, the control unit controls the high-voltage control circuit 31 and controls the energization of the electromagnet 35 provided in the fuel injection valve. The timing circuit 32 and the drive control circuit 33
Or may be provided separately.

The electromagnet 35 is energized or de-energized based on a control signal from the drive control circuit 33. As described above, when excited, the electromagnet 35 attracts the needle and injects fuel. On the other hand, when demagnetized, the electromagnet 35 stops the needle suction operation and stops the fuel injection.

The high-side switch SW1 connected to the drive control circuit 33 controls the switching of the power supplied from the vehicle-mounted battery voltage of 12 V to control the current flowing through the electromagnet 35 to a predetermined target holding current. . Here, the target holding current is a current that flows through the electromagnet 35 in order to hold the fuel injection valve in an open state. Similarly, the high-side switch SW2 connected to the drive control circuit 33 is a switch for passing the electric energy stored in the capacitor C1 to the electromagnet 35 as an exciting current.

Further, the low side switch SW3 connected to the drive control circuit 33 is a switch that is turned on when the electromagnet 35 is energized, and operates to discharge the current flowing through the electromagnet 35. These switches SW1
SW3 are controlled on / off by the drive control circuit 33 in accordance with a control signal from the timing circuit 32.

A resistor R is connected between the low-side switch SW3 and the ground. By detecting the current flowing through the resistor R, the value of the current flowing through the electromagnet 35 can be detected.

The abnormality determination unit 37 detects a current after a lapse of a predetermined time from the start of energization of the electromagnet in order to open the fuel injection valve by using a resistor R, and determines this by a predetermined threshold value. In comparison, a short circuit and a disconnection in the fuel injection valve are determined. Specifically, if the detected current exceeds the first threshold, it is determined that a short circuit has occurred in the fuel injection valve, and if the detected current has fallen below the second threshold, For example, it is determined that a disconnection has occurred in the fuel injection valve. FIG. 3A schematically illustrates an example in which the coil of the electromagnet 35 of the fuel injection valve is short-circuited, and FIG. 3B schematically illustrates an example in which the coil of the electromagnet 35 of the fuel injection valve is disconnected.

Since the rise of the drive current varies depending on the fuel injection valve, the first and second thresholds are
Preferably, the setting is made in consideration of the individual characteristics of each fuel injection valve. For example, the rise of the drive current is monitored in advance for each fuel injection valve, and the range of variation in the rise of the normal drive current is determined. The first and second thresholds are set so as not to fall within the range of the normal drive current variation.

Alternatively, the timing for comparing the drive current with the threshold current may be set in consideration of the characteristics of the fuel injector. For example, the comparison timing is set earlier for a fuel injection valve whose drive current rises relatively slowly, and the comparison timing is set earlier for a fuel injector whose drive current rises relatively fast.

When the abnormality determination section 37 determines that a short circuit or a disconnection has occurred, the abnormality determination section 37 outputs a control signal indicating that these abnormalities have occurred to the drive control circuit 33. In response to this, the drive control circuit 33 stops energizing the electromagnet 35. For example, upon receiving the abnormality determination, the drive control circuit 33 simultaneously receives the high-side switch SW2 or the low-side switch S2.
W3 is turned off. Alternatively, only when it is determined that a short circuit occurs, the switch SW2 or SW3 may be turned off. By doing so, it is possible to prevent the overcurrent from flowing through the electromagnet and destroying the drive element.

A part of the fuel injection valve drive circuit shown in FIG. 2, for example, a high voltage control circuit 31, a drive control circuit 33,
The timing circuit 32 and the like can be designed to be shared for each fuel injection valve. Abnormality judgment unit 3
7 can also be shared for each fuel injection valve, but even in this case, the abnormality determination is performed individually for each fuel injection valve. Also, the switches SW1 to SW1
SW3 is designed to operate individually for each fuel injector and a resistor R is provided separately for each fuel injector.

As described above, the abnormality determination is executed individually,
When it is determined that the fuel injection valve is abnormal, the switches SW2 and SW3 designed to operate individually for each fuel injection valve are operated, whereby only the cylinder corresponding to the fuel injection valve in which the abnormality has occurred becomes inoperable. . The other cylinders can continue to operate as they are, so that the self-propelled state can be maintained.

In another embodiment, when opening the fuel injection valve, the abnormality judging section 37 refers to a threshold value map (not shown) set in consideration of the driving state of the vehicle. Thereby, the first and second threshold values are determined.
For example, the threshold value map is a map showing a correspondence relationship between the engine speed Ne, the intake pipe pressure Pb, the first threshold value, and the second threshold value.

In still another embodiment, the abnormality determining unit 37
When the fuel injection valve is opened, the first and second threshold values and the drive current are determined by referring to a timing map (not shown) which is set in advance in consideration of the operation state of the vehicle. Is determined. For example, this timing map is a map showing the correspondence between the engine speed Ne, the intake pipe pressure Pb, and the comparison timing.

FIG. 4 shows drive signals, switches SW1 to SW
3 shows the ON / OFF state of No. 3 and the time waveform of the drive current flowing through the electromagnet 35. The valve opening operation of the fuel injection valve will be described with reference to FIGS. The drive current waveform 50 shown in FIG. 4 indicates the magnitude of the current flowing through the electromagnet 35.

The drive control circuit 33 which has received the drive signal from the timing circuit 32 outputs a control signal for stopping the boosting to the high voltage control circuit 31 in response thereto. This boost stop control signal is output until time t2 when the operation shifts to the holding operation. When the boost stop signal is output, a high voltage has already been stored in the capacitor C1 by the high voltage control circuit 31.

The drive control circuit 33 turns on the high-side switch SW2 and the low-side switch SW3 at the same time as receiving the drive signal (time t1).
As a result, the electric energy stored in the capacitor C1 flows as an exciting current through the high-side switch SW2 to the electromagnet 35 and the low-side switch SW3. When the electromagnet 35 is energized, the operation of attracting the movable member is performed as described above, whereby the fuel injection valve opens and injects fuel.

At time t2, the high-side switch SW2 is turned off, and the on / off switching control of the high-side switch SW1 is started in order to shift to the holding operation for holding the open state of the fuel injection valve. Thus, feedback control is performed so that the holding current flowing through the electromagnet 35 (which is detected by the resistor R) becomes a predetermined target holding current.

At time t3, when the drive signal from the timing circuit 32 is turned off (when it is deasserted), the drive control circuit 33 turns off the high-side switch SW1 and the low-side switch SW3 in response thereto. I do. Thus, the fuel injection valve is closed, and the fuel injection is stopped.

For convenience, the excitation operation of the electromagnet by the high voltage at times t1 to t2 is referred to as an initial overexcitation operation, and is performed at times t2 to t2.
The operation of applying a holding current to the electromagnet to hold the fuel injection valve 3 in the open state is referred to as a holding operation.

FIG. 5 is an enlarged view of the time waveform 50 of the current flowing through the electromagnet in the initial overexcitation operation executed at times t1 to t2 in FIG. A broken line 51 shows a time waveform of the drive current when a short circuit occurs in the fuel injection valve, and a broken line 52 shows a time waveform of the drive current when a disconnection occurs in the fuel injection valve. When a short circuit occurs, the drive current rises rapidly as described above. On the other hand, when the wire is disconnected, no drive current flows through the electromagnet 35. Therefore, if the drive current falls within the range of the first and second thresholds after a lapse of a predetermined time from the start of the supply of the drive current to the electromagnet 35, no short circuit or disconnection occurs. Can be determined.

Therefore, the drive current after a lapse of a predetermined time T from the start of energization of the electromagnet 35 is monitored, and if the drive current exceeds a predetermined first threshold value,
It is determined that a short circuit has occurred in the fuel injection valve, and if the shortfall is below a second predetermined threshold value, it is determined that a disconnection has occurred in the fuel injection valve. First and second
Is preferably set in consideration of individual variations of the fuel injection valves.

FIG. 6 is a flowchart executed by the abnormality judging section 37 for judging a short circuit / break in the fuel injection valve. In step 101, it is determined whether or not the timer started at the same time as the start of the supply of the drive current to the electromagnet has reached zero. This timer is a down timer in which a predetermined time T (FIG. 5) is set. If the timer has not reached zero, it indicates that the predetermined time T has not yet elapsed, and the process directly exits this routine. When the timer reaches zero, it indicates that a predetermined time has elapsed, and the process proceeds to step 102.

In step 102, the resistance R
The drive current I flowing through the electromagnet is detected. Step 103
, The driving current I is compared with the first threshold value, and if the former is larger than the latter, it is determined that a short circuit has occurred (step 1).
04). On the other hand, if the driving current I is equal to or smaller than the first threshold, the process proceeds to step 105, where the driving current I is compared with the second threshold. If the former is smaller than the latter, it is determined that there is a disconnection (106). When the drive current I is equal to or less than the first threshold,
If the current value is equal to or more than the second threshold value, it is a normal drive current value, and the process exits this routine.

Although the above embodiment has been described with respect to a fuel injection valve driving apparatus applied to a direct injection type internal combustion engine, a method for determining a short circuit and a disconnection in the fuel injection valve is described in another internal combustion engine. The present invention can also be applied to the fuel injection valve described above. Further, the present invention can be applied to determination of a short circuit and a disconnection not only in the fuel injection valve but also in another electromagnetic actuator such as an intake / exhaust valve.

[0054]

According to the present invention, disconnection and short circuit in the fuel injection valve can be determined. Furthermore, according to the present invention, the vehicle can run on its own even if it is determined that the abnormality is abnormal.

[Brief description of the drawings]

FIG. 1 is a diagram showing a mechanical structure of a fuel injection valve according to an embodiment of the present invention.

FIG. 2 is an overall block diagram of a fuel injection valve driving circuit in one embodiment of the present invention.

FIG. 3 is a diagram schematically showing a short circuit and a disconnection in the fuel injection valve in one embodiment of the present invention.

FIG. 4 is a diagram showing a time waveform of each signal when the fuel injection valve is opened in one embodiment of the present invention.

FIG. 5 shows the rise of the drive current at the time of normal operation, at the time of short circuit, and at the time of disconnection when the fuel injection valve is opened in one embodiment of the present invention.

FIG. 6 is a flowchart for determining a short circuit and a disconnection in a fuel injection valve in one embodiment of the present invention.

[Explanation of symbols]

 31 High voltage control circuit 32 Timing circuit 33 Drive control circuit 35 Electromagnet 37 Abnormality judgment unit

 ────────────────────────────────────────────────── ─── Continued from the front page (72) Kunihiro Morishita, Inventor Kunihiro Morishita 1-4-1 Chuo, Wako-shi, Saitama F-term in Honda R & D Co., Ltd. (Reference) 3G066 AA02 AB02 BA31 CC06U CD26 CE22 CE29 DC09 DC19 DC26 3G301 HA04 JB02 LB04 NC02 PA07B PE01B PG02B

Claims (6)

[Claims] A fuel injection valve having an electromagnet, which is opened by energizing the electromagnet; and a fuel injection valve which is provided in series with the electromagnet and which is connected to the electromagnet after a lapse of a predetermined time from the energization of the electromagnet. Current detection means for detecting a flowing current; and if the current detected by the current detection means exceeds a predetermined first threshold value, a short circuit has occurred in a current path in the fuel injection valve. And the current detected by the current detecting means is determined by a predetermined second
Abnormality determination means for determining that a disconnection has occurred in the current path of the fuel injection valve if the threshold value is below the threshold value. 2. The fuel injector driving device according to claim 1, wherein said current detecting means is a resistor connected in series to said electromagnet. 3. The fuel injection valve driving device according to claim 1, further comprising an energization stopping means for stopping energization of the electromagnet when the abnormality judging means judges that the electromagnet is abnormal. 4. The fuel injection valve driving device according to claim 2, wherein the first threshold value and the second threshold value are set so as to be adapted to the characteristics of each fuel injection valve. 5. The timing at which the current detected by the current detecting means is compared with predetermined first and second thresholds is set so as to match the characteristics of each fuel injection valve. The fuel injector drive device according to claim 1. 6. The fuel injection valve driving device according to claim 1, wherein the fuel injection valve is mounted on a direct injection type internal combustion engine.