JP2001012284A - Injector control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an injector control device which can ensure proper injection characteristics even when injection ending is in the vicinity of switching of a fixed current value. SOLUTION: Relating to solenoids 101a, 102a, 103a, 104a for valve opening injectors 101, 102, 103, 104 for a Diesel engine, first the solenoid is fixed current- controlled for a prescribed period by a first prescribed current value, after the prescribed period, fixed current control is performed to the current carrying stop timing in accordance with an injection amount by a second prescribed current value lower than the first prescribed current value. An ECU 200, judging the current carrying stop timing in accordance with the injection amount for whether it is shorter or longer than the prescribed period, advances the current carrying stop timing when it is judged shorter or delays the current carrying stop timing when it is judged longer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injector control device for injecting and supplying fuel to an engine, and more particularly to a two-stage constant current control capable of switching between a high current and a low current when the injector is driven at a constant current. The present invention relates to an injector control device having a function.

[0002]

2. Description of the Related Art Conventionally, in the constant current control of an injector, there is a two-stage constant current control system as disclosed in Japanese Patent Publication No. 7-78374. This is the minimum current required to maintain a high current to ensure reliable opening even when the movable part suddenly bounces due to energization of the injector, and to close the valve quickly and suppress unnecessary energy consumption. It is to switch to a low current.

FIG. 9 shows an example of the configuration of this type of device (vehicle injector control device). In FIG. 9, a DC-DC converter 302 and a battery power supply are connected to a solenoid 301a of an injector 301,
When the switches 304, 305, and 306 are turned on by C303, high energy from the DC-DC converter 302 and low energy from the battery power supply can be supplied to the solenoid 301a of the injector 301. That is, as shown in FIG. 10, the driving IC 303 receives the injection signal # 1 according to the engine operating state from the microcomputer 307, and switches the switches 304 to 306.
On / off control. More specifically, the driving IC 303 turns on the switches 306 and 304 in accordance with the injection signal # 1, and discharges the charging voltage of the capacitor 302a to the solenoid 301a of the injector 301 to cause the injection of the injector 30.
1, a large current flows at the beginning of valve opening to improve the valve opening responsiveness of the injector 301, and a switch 305 according to the injector current I _INJ detected by the resistor 308.
Is turned on / off to set the injector 301 to the high current value Ic1.
To secure a reliable valve opening even when the movable part suddenly bounces due to energization of the injector 301. After that, the low current value Ic2 which is the minimum necessary to hold
Switch to constant current drive to speed up valve closing and reduce unnecessary energy consumption.

Here, the driving IC 303 outputs the injection signal #
A constant current value switching signal SG1 for a certain period of time T1 is generated for 1 to switch the constant current value.

[0005]

However, when an injection signal corresponding to the engine operation is continuously input, the high current value Ic1
When energization ends during constant current control in (TQ <T1)
And when the energization ends during the constant current control at the low current value Ic2 (TQ> T1), the valve closing time differs and a malfunction occurs. Specifically, when the valve closing by the spring of the injector 301 is at the high current value Ic1 (TQ <T1), the residual energy is large, so the valve closing is delayed and the injection amount increases, and when the valve closing is at the low current value Ic2 (TQ> T1). ) Has a small residual energy, so the valve closes quickly and the injection amount decreases. Therefore, as shown in FIG. 11, in the relationship between the calculated injection time and the actual injection amount, the fuel injection amount (the injection signal ON level period T
Even if Q) is gradually increased, the injection amount decreases near the switching of the constant current value. That is, a step is formed in the relationship between the injection time and the injection amount. Such a level difference (dent) of the injection amount causes deterioration of the riding comfort, smoke, N
There is a problem that the generation of Ox increases.

Although the injection amount can be corrected before and after the switching of the current value, if the constant current switching time is made in the driving IC 303, it is not clear which of the higher or lower current is used to close the valve. Therefore, the injection amount cannot be corrected.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an injector control device capable of ensuring good injection characteristics even when the injection is completed near the switching of the constant current value.

[0008]

According to the first aspect of the present invention, a constant current control is performed on the solenoid at a first predetermined current value for a predetermined period, and after the predetermined period, the constant current is controlled to be higher than the first predetermined current value. When the constant current control is performed at a low second predetermined current value until the energization stop timing corresponding to the injection amount, it is determined whether the energization stop timing according to the injection amount is shorter or longer than a predetermined period, and when it is determined to be short. When it is determined that the power stop timing is advanced or long, the power stop timing is delayed, and the power stop timing can be optimized.

According to a third aspect of the present invention, in the injector control device according to the first aspect, if the injection time calculated by the adaptation at the second predetermined current value is shorter than the predetermined time, the power supply is stopped. In order to advance the timing, a predetermined value may be subtracted from the injection time. According to a fourth aspect of the present invention, in the injector control device according to the first aspect, if the injection time calculated by the adaptation at the first predetermined current value is longer than the predetermined time, the injection stop timing is delayed. , A predetermined value may be added to the injection time.

According to the second aspect of the present invention, the constant current control is performed on the solenoid at the first predetermined current value for a predetermined period, and after the predetermined period, the second predetermined current is lower than the first predetermined current value. When performing the constant current control to the power supply stop timing according to the injection amount using the value, when the power supply stop timing according to the injection amount is substantially equal to the end of the predetermined period, the period of the constant current control at the first predetermined current value is extended. Is done.

Therefore, by optimizing the period in which the constant current control is performed at the first predetermined current value, even if the injection end is near the switching of the constant current value, there is no step (dent) in the injection characteristics, and good injection characteristics are obtained. Injection characteristics can be ensured.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A first embodiment of the present invention will be described below with reference to the drawings.

The present embodiment is embodied as a common rail type fuel injection system for an on-vehicle four-cylinder diesel engine. Injection is supplied to each cylinder of the diesel engine.

FIG. 1 is an electric circuit diagram showing an injector control device according to the present embodiment. 1 is an injector 1 that injects fuel into each cylinder of an engine.
01, 102, 103, 104 and a driving circuit (EDU: Electric) for driving these injectors 101-104.
A driver unit (ECU) 100 and an electronic control unit (ECU) 200 connected to the drive circuit 100 are provided. ECU
Reference numeral 200 includes a known microcomputer including a CPU, various memories, and the like. An injection signal に for each cylinder is provided based on engine operation information detected by various sensors such as an engine speed Ne, an accelerator opening ACC, and an engine coolant temperature THW. 1 to # 4 are generated and output to the drive circuit 100. The ECU 200 also generates a constant current value switching signal SG1 for performing the two-stage constant current control and outputs the signal SG1 to the drive circuit 100.

The injectors 101 to 104 are constituted by normally closed solenoid valves, and have solenoids 101a, 102a, 1
03a and 104a are individually provided. In this case, when each of the solenoids 101a to 104a is energized, a valve body (not shown) moves to the valve opening position against the urging force of the return spring, and fuel injection is performed. Also, each solenoid 101
When the energization of a to 104a is interrupted, the valve body returns to the original valve closing position, and the fuel injection is stopped.

In the present embodiment, the injectors 101 to 104 of all four cylinders are divided into two cylinders,
01 and 103 as the same injection group
Of the injectors 102 and 1
04 are connected to the common terminal COM2 of the drive circuit 100 as the same injection group.

The inductor L00 has one end connected to the battery power supply line (+ B) and the other end connected to a transistor (switching element) T00. Hereinafter, all the transistors are used as switching elements. A self-excited oscillation circuit 110 is connected to the gate terminal of the transistor T00.
Is connected, and the transistor T00 is turned on / off according to the output of the circuit 110. Also, the transistor T00
The current detection resistor R00 is connected between the power supply and GND.

One end of a capacitor C10 is connected between the inductor L00 and the transistor T00 via a backflow preventing diode D13, and one end of a capacitor C20 is connected via a backflow preventing diode D23. I have. The other ends of these capacitors C10 and C20 are connected to a connection point between the transistor T00 and the current detection resistor R00.

The capacitor C10 is an energy storage capacitor dedicated to the injectors 101 and 103 which are the injection group on the COM1 side.
Is an injector 10 which is an injection group on the COM2 side.
It is an energy storage capacitor dedicated to 2,104.

The inductor L00 and the transistor T0
0, a current detection resistor R00, an oscillation circuit 110, diodes D13 and D23, and capacitors C10 and C20.
A DC converter is configured; Transistor T0
When 0 is turned on / off, the capacitors C10 and C20 are charged through the diodes D13 and D23. As a result, each of the capacitors C10 and C20 becomes the battery voltage + B
To a higher voltage. In such a case, while the charging current is monitored by the current detection resistor R00, the oscillation circuit 1
By turning on / off the transistor T00 by 10, the capacitors C10 and C20 are charged at an efficient cycle. The capacitors C10 and C20 are always fully charged.

The drive IC 120 is connected to input terminals # 1 to # 4, and the drive IC 120 receives signals from the ECU 200 through these terminals from the first cylinder (# 1) to the fourth cylinder (#).
Each injection signal of 4) is taken in. The driving IC 120
Inputs a constant current value switching signal SG1 from the ECU 200.

The transistors T12 and T22 are # 1 to #
A transistor for supplying (discharging) the energy stored in the capacitors C10 and C20 to the injectors 101 to 104 at a timing when the injection signal of No. 4 is inverted from OFF (logic low level) to ON (logic high level). It is. More specifically, the transistor T12 is provided between the capacitor C10 and the common terminal COM1, and when the transistor T12 is turned on by the driving IC 120, the energy stored in the capacitor C10 becomes COM.
It is supplied to the injectors 101 and 103 on one side. The transistor T22 is provided between the capacitor C20 and the common terminal COM2, and when the transistor T22 is turned on by the driving IC 120, the energy stored in the capacitor C20 is reduced by the injectors 102, 1 on the COM2 side.
04. Such capacitors C10 and C20
As a result, a large current flows as a driving current for the injector, and accordingly, the valve opening response of the injector is improved.

On the low side of each of the injectors 101 to 104, terminals INJ1, INJ2, I
Transistors T10 and T2 via NJ3 and INJ4
0, T30 and T40 are connected, and the driving IC 12
When the injection signals of # 1 to # 4 are respectively supplied from 0 to the transistor T1 by the injection signal of the logic high level,
0 to T40 are turned on. Transistors T10, T30
And the transistors T20 and T40 constitute the same injection group, and each transistor is grounded via a current detection resistor R10, R20 for each group. The drive current flowing through the injectors 101 to 104 is detected by the current detection resistors R10 and R20, and the detection result is taken into the drive IC 120.

The terminals COM1 and COM2 are connected to a battery power line (+ B) via diodes D11 and D21 and transistors T11 and T21, respectively. In such a case, the driving IC 120 is connected to the injector 1
01 to 104 according to the drive current flowing through the transistor T
11, ON / OFF control of T21. Thereby, + B
Supplies a constant current to the injectors 101-104. The diodes D12 and D22 are feedback diodes for constant current control, and the current flowing through the injectors 101 to 104 when the transistors T11 and T21 are turned off is returned via the diodes D12 and D22.

In the actual operation, the transistor T12 or T22 is first turned on at the same time as the rise of the injection signal which is a drive command, and after a large current flows as the drive current for the injectors 101 to 104 due to the energy release of the capacitors C10 and C20. Subsequently, a constant current flows through the transistor T11 or T21, and the driving current is cut off as the injection signal falls. The diodes D11 and D21 are connected to the high potentials COM1 and COM2 when the capacitors C10 and C20 release energy.
This is a diode for preventing the wraparound from the two terminals to the + B side.

In addition, of the injectors 101 to 104, the injectors 10 constituting one injection group
1 and 103 are connected to the capacitor C10 via the diodes D10 and D30, and the back electromotive force energy generated in the injectors 101 and 103 due to the cutoff of the current is supplied to the capacitor C1 via the diodes D10 and D30.
Collected to 0. Further, the injectors 102 and 104 constituting the other injection group include diodes D20 and D20.
The counter electromotive energy generated in the injectors 102 and 104 due to the cutoff of the current is recovered to the capacitor C20 through the diodes D20 and D40.

The drive IC 120
Signal # 1 to # 4 and constant current value switching signal SG
1 is output, but the ECU 200 outputs the switching signal SG
The injection end time is corrected based on 1 (details will be described later).

Next, the operation of this embodiment will be described with reference to FIG.
This will be described with reference to the time chart of FIG. In FIG. 2, the constant current value switching signal SG
1, the injection signal # 1 of the first cylinder, and the current detection resistor R10
Drive current (INJ1 current) detected by the terminal IN
The potential of J1 is shown.

FIG. 2 shows a state where two-stage constant current control is performed. In other words, when focusing on the INJ1 current, the solenoid is first subjected to constant current control for a predetermined period T1 at a first predetermined current value (for example, 10 amps). As a result, a reliable valve opening can be ensured even if the valve body suddenly bounces due to energization of the injector. Thereafter, constant current control is performed at a second predetermined current value (for example, 5 amperes) lower than the first predetermined current value until the power supply stop timing t3 according to the injection amount. This allows
Valve closing is quicker, and unnecessary energy consumption is suppressed. The signal SG1 is used for switching the current value in the two-stage constant current control. That is, in FIG. 2, both signals SG1 and # 1 are turned on at the same time, signal SG1 is turned off after a predetermined time T1 has elapsed, and injection signal # 1 is turned off after a time TQ corresponding to the injection amount has elapsed. Here, when the signal SG1 is on, the injector current is high (for example, 10 amps), and when the signal SG1 is off and the injection signal # 1 is on, the injector current is low (for example, 5 amps).
Is controlled. Further, in FIG. 2, a case where the on-time TQ of the injection signal # 1 is longer than the on-time T1 of the constant current value switching signal SG1 (TQ> T1) is shown by a solid line, and conversely, the on-time TQ is changed to the on-time T1. The shorter case (TQ <T1) is indicated by a dashed line.

On the other hand, the ECU 200 executes signal processing shown in FIG. 3, and a signal from the ECU 200 to the driving IC 120 is generated by processing according to this flowchart.

The ECU 200 determines in step 100
The injection amount adapted to the low current value (5 amps) of the multi-stage constant current control is calculated, and the injection time TQ with the cutoff current value Ic set to 5 amps is calculated. Then, in step 101, the ECU 200 compares the injection time TQ with the predetermined time T1 to determine whether the injection time TQ is shorter than the predetermined time T1. If the injection time TQ is shorter than the predetermined time T1, EC
U200 subtracts a predetermined value α from the injection time TQ in step 102, and updates this as a new injection time TQ. The α value here is a difference (= τ1−τ2) between the valve closing delay amount τ1 from 10 amps and the valve closing delay amount τ2 from 5 amps, as shown in FIG. As a result, the power supply stop timing t3 ′ in FIG. 2 is advanced. If the injection time TQ is longer than the predetermined time T1 in step 101, the ECU 200 bypasses the processing in step 102.

The ECU 200 determines in step 102 or 10
After the execution of Step 1, the present process is terminated. Then, as shown in FIG. 2, when the injection signals # 1 to # 4 from the ECU 200 and the constant current value switching signal SG1 are simultaneously input to the driving IC 120, the transistors T10 and T20 corresponding to the injection signals at the timing of t1. , T30, and T40 are turned on, and at the same time, when the injection signal # 1 or # 3 is input, the transistor T12 is turned on. When the injection signals # 2 and # 4 are input, the transistor T22 is turned on for a short time.
The energy stored in C20 is released, and a large current is caused to flow through the injector to speed up the valve opening.

That is, before the injection of FIG. 2, the capacitors C10 and C20 are in a fully charged state, and when the injection signal of # 1 is turned on at the timing of t1, the transistor T10 is turned on and at the same time. The transistor T12 is turned on, and the injection by the injector 101 is started. When the energizing current value (INJ1 current) reaches a predetermined value I0 after the transistor T12 is turned on, the transistor T12 is turned off because it emits predetermined energy required for one injection.

After releasing the energy of the capacitor C10,
Subsequently, the transistor T11 is turned on / off, and a constant current is supplied to the injector 101 via the diode D11. That is, the driving IC 120 turns on / off the transistor T11 according to the driving current (INJ1 current) detected by the current detection resistor R10, and holds the driving current at a predetermined value (for example, 10 amps).
That is, the current value of the injector is detected by the resistor R10 (R20), and the transistor T11 (T21) is turned on / off.
By turning it off, constant current control is performed.

Further, at the timing of t2 in FIG. 2, the threshold level of the current detection value by the resistors R10 and R20 is switched by the constant current value switching signal SG1 from the ECU 200 to change the constant current value (for example, 5 amps). As a result, the injector 101 is held in the valve open state.

Thereafter, at the timing of t3, # 1
Is turned off, the transistor T10 is turned off, the injector 101 is closed, and the injector 10 is closed.
The injection by 1 is terminated. The back electromotive force energy generated when the power supply to the injector 101 is cut off is a diode D1
0 is collected in the capacitor C10. At this time,
Energy is recovered by the same capacitor C10 that released energy at the start of injection.

Thereafter, similarly, an injection signal corresponding to the engine operation is continuously generated, and the fuel is injected by the injector. The fuel injection is performed in this manner. By executing the processing of FIG. 3, the injection signals # 1 to # 4
In the case of FIG. 11, a step occurs in the injection characteristics when the injection end is near the switching of the constant current value in the case of FIG. 11, but in the present embodiment, as shown in FIG. Even before and after the value switching, the injection amount difference due to the valve closing delay disappears.

As described above, this embodiment has the following features. (A) The injection signals # 1 to # 4 and the constant current value switching signal SG1 are output from the ECU 200, and the execution of the process of FIG. 3 causes the injection ending time (the timing of t3 ′ in FIG. 2) according to the switching signal. ) Was corrected. That is,
It is determined whether the power supply stop timing according to the injection amount is shorter than a predetermined period, and when the power supply stop timing is determined to be shorter, the power supply stop timing is advanced. Therefore, by optimizing the power-supply stop timing, good injection characteristics can be ensured even when the injection end is near the switching of the constant current value. As a result, the riding comfort can be improved and the generation of smoke and NOx can be suppressed. (Second Embodiment) Next, a second embodiment will be described with reference to the first embodiment.
The following description focuses on the differences from this embodiment.

As a correction method instead of FIG. 3, in this example,
The flow shown in FIG. 5 is executed. In step 200, the ECU 200 calculates an injection amount adapted at a high current value (10 amps) of the multi-stage constant current control, and calculates an injection time TQ in which the cutoff current value Ic is 10 amps. Then, the ECU 200 determines in step 201 that
The injection time TQ is compared with the predetermined time T1 to determine whether the injection time TQ is longer than the predetermined time T1. If the injection time TQ is longer than the predetermined time T1, the ECU 200 proceeds to step 20.
In step 2, a predetermined value α is added to the injection time TQ, and this is updated as a new injection time TQ. As a result, the power supply stop timing t3 in FIG. 2 is delayed. Step 20
1 and the injection time TQ is shorter than the predetermined time T1, the ECU 2
00 bypasses the processing of step 202.

The ECU 200 proceeds to step 202 or 20
After the execution of Step 1, the present process is terminated. In this way, by correcting the injection signals # 1 to # 4, as shown in FIG. 6, even when the injection ends before and after the switching of the constant current value, the injection amount difference due to the valve closing delay disappears.

As described above, it is determined whether the power supply stop timing according to the injection amount is longer than a predetermined period, and when it is determined that the power supply stop timing is longer, the power supply stop timing is delayed to optimize the power supply stop timing. Also, even when the end of the injection is near the switching of the constant current value, good injection characteristics can be ensured. (Third Embodiment) Next, a third embodiment according to claim 2 will be described.

In this example, the flow shown in FIG. 7 is executed. After calculating the injection amount and calculating the injection time TQ, the ECU 200 determines in step 300 whether the absolute value of the difference between the injection time TQ and the predetermined time T1 is smaller than a predetermined value γ. That is, the power supply stop timings t3 and t in FIG.
It is determined whether 3 ′ is substantially equal to the end of the predetermined period T1. When | TQ−T1 | is smaller than a predetermined value γ,
The ECU 200 converts the correction value ΔT1 to the T1 value in step 301.
And updates this as a new T1 value. That is, the constant current control period T1 at 10 amps in FIG. 2 is extended. As a result, the injection characteristics are as shown in FIG.

As described above, when it is uncertain whether the current value becomes high or low at the end of the injection, the switching signal is extended,
By performing the energization cut from the high current value, it is possible to perform good injection amount control with reliable correction.

This example can be used in combination with the first or second embodiment. As described above, the present embodiment has the following features. (A) When the power-supply stop timing according to the injection amount is substantially equal to the end of the predetermined period, the period of constant current control at the first predetermined current value is extended. Therefore, by optimizing the period in which the constant current control is performed at the first predetermined current value, even if the injection end is near the switching of the constant current value, there is no step (dent) in the injection characteristics, and good injection characteristics can be obtained. Can be secured. As a result, the riding comfort can be improved and the generation of smoke and NOx can be suppressed.

In the above description, the present invention is applied to the control device of the injector of the diesel engine, but may be applied to the control device of the injector of the gasoline engine.

[Brief description of the drawings]

FIG. 1 is an electric circuit diagram showing an injector control device according to an embodiment.

FIG. 2 is a time chart for explaining the operation.

FIG. 3 is a flowchart for explaining the operation of the first embodiment.

FIG. 4 is an injection characteristic diagram for explaining the operation of the first embodiment.

FIG. 5 is a flowchart for explaining the operation of the second embodiment.

FIG. 6 is an injection characteristic diagram for explaining the operation of the second embodiment.

FIG. 7 is a flowchart for explaining the operation of the third embodiment.

FIG. 8 is an injection characteristic diagram for explaining the operation of the third embodiment.

FIG. 9 is a diagram showing a configuration example of an injector control device for explaining a conventional technique.

FIG. 10 is a time chart for explaining a conventional technique.

FIG. 11 is an injection characteristic diagram for explaining a conventional technique.

[Explanation of symbols]

101, 102, 103, 104 ... injector, 10
1a, 102a, 103a, 104a ... solenoid, 1
20: drive IC, 200: ECU, C10, C20 ...
Capacitor, R10, R20 ... resistance, T10, T20,
T30, T40: transistors; T12, T22: transistors.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Satoru Kawamoto 1-1-1 Showa-cho, Kariya-shi, Aichi F-term in Denso Corporation (reference) 3G066 AA07 AB02 AC09 BA19 BA24 BA25 CC06U CC53 CD26 CE22 3G301 HA02 JA14 LB11 LC10 MA11 PE01Z PE08Z PF03Z

Claims (4)

[Claims] An injector for supplying fuel to an internal combustion engine is provided. A solenoid for opening the injector is first controlled at a first predetermined current value for a predetermined period at a constant current, and after a predetermined period, the first current is controlled. In the injector control device, which performs constant current control at a second predetermined current value lower than the predetermined current value until the power supply stop timing corresponding to the injection amount, whether the power supply stop timing according to the injection amount is shorter than the predetermined period An injector control device that determines whether the current is long or not and advances the power stop timing when it is determined to be short, or delays the power stop timing when it is determined to be long. 2. An injector for supplying fuel to an internal combustion engine, wherein a solenoid for opening the injector is first subjected to constant current control at a first predetermined current value for a predetermined period, and after a predetermined period, the first current is controlled. In the injector control device that performs constant current control at a second predetermined current value lower than the predetermined current value until the power supply stop timing corresponding to the injection amount, the power supply stop timing according to the injection amount is substantially equal to the end of the predetermined period. An injector control device, wherein when equal, a period in which the constant current control is performed at the first predetermined current value is extended. 3. The injector control device according to claim 1, wherein if the injection time calculated by the adaptation at the second predetermined current value is shorter than a predetermined time, the injection time is set to a predetermined value in order to advance the power stop timing. An injector control that subtracts a value. 4. The injector control device according to claim 1, wherein when the injection time calculated by the adaptation at the first predetermined current value is longer than a predetermined time, the injection time is set to a predetermined value so as to delay the power stop timing. An injector control device that adds values.