JP2935499B2 - Driving device for piezo type injection valve for diesel engine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a driving apparatus for a piezo-type injection valve for a diesel engine that performs main injection and sub-injection.

[Problems to be solved by conventional technology and invention]

In a diesel engine, sub-injection (also referred to as pilot injection) is performed prior to main injection of fuel in order to reduce noise and vibration particularly at low engine speeds. On the other hand, a piezo-type injection valve that controls a hydraulic pressure by using a piezoelectric laminate is known (see Japanese Utility Model Laid-Open No. 61-187965).

A conventional driving device for a piezo-type injection valve for a diesel engine which performs a main injection and a sub-injection is of a power supply circuit-circuit type as shown in, for example, FIGS.
No. 165).

In FIG. 15, reference numeral 1 denotes a battery of, for example, 12 V, the voltage of which is applied via a key switch 2 to a high voltage generating circuit (flyback DC / DC converter) 3 composed of an oscillation circuit and a step-up transformer. Have been. The high voltage generating circuit 3 converts the battery voltage 12 V to, for example, 600 V and applies the converted voltage to the capacitor 4. Between the capacitor 4 and the piezo element 9, a charge thyristor 5 and a coil 6 as charge switching means are provided, and a coil 7 and a discharge thyristor 8 as discharge switching means are provided. Charging thyristor 5 is turned on by closing pulse P ₁ from CPU, the discharge thyristor 8 is turned on by a valve opening pulse P ₁ 'by the CPU. The coil 6 is connected to a closed circuit of the capacitor 4, the charging thyristor 5, and the piezo element 9 formed when the charging thyristor 5 is turned on.
This is for forming a resonance circuit, thereby increasing the voltage boost of the piezo element 9, and the coil 7 is a closed circuit of the charging thyristor 8 and the piezo element 9 formed when the discharge thyristor 8 is on. To increase the voltage drop of the piezo element 9.

As shown in FIG. 16, in order to cause the sub-injection and the main injection to be performed at times T ₁ and T ₂ respectively by the drive device of FIG. 15, the valve closing pulse P ₁ , the valve opening pulse P ₁ ′, and the valve closing pulse P _1, and generates a valve opening pulse P ₁ ', the injection interval T ₀ between the auxiliary injection and main injection becomes shorter, the charging thyristor 5 is turned on before the capacitor voltage V _C reaches a predetermined value as a result, as the drive voltage V _D of the piezoelectric element 9 is shown in FIG. 17, the driving voltage V _D injection interval T ₀ of ￫￫￫￫￫ ... next ,, points auxiliary injection and main injection in accordance with the Therefore, there is a problem that a stable displacement amount cannot be obtained and the main injection amount decreases. Note that in FIG. 15, by using the charging capability of the high voltage generating circuit 3 is very large, although injection interval T ₀ can be a predetermined voltage capacitor voltage V _C be short, in this case, a high voltage generator The circuit 3 becomes larger,
It is not practical because the conversion efficiency also deteriorates.

In the power supply circuit-circuit system shown in FIG. 18, a flyback type DC / DC converter 3 'is used as a high voltage generation circuit.
Therefore, a driver circuit 3a for charging the flyback type DC / DC converter ′ is provided,
A diode 11 is provided in place of the capacitor 4, the charging thyristor 5, and the coil 6 in the figure. In this case, the 19th
As shown, prior to the sub injection time T ₁ and the main injection time T ₂
The output voltage of the DC / DC converter 3 'in order to a predetermined value, i.e., DC / DC to the primary current i ₁ to a predetermined value
It must be the energization time T _X of the energization time T _X ie drivers 3a of converter 3 'constant, the energization time T _X
Since it depends on the voltage of the battery 1, control of each injection timing is difficult and not practical.

Therefore, an object of the present invention is to stabilize the main injection amount when performing the sub-injection and the main injection in the drive device of FIG.

Another object of the present invention is to provide a driving apparatus for a piezo-type injection valve for a diesel engine that is resistant to failure (abnormality).

[Means for solving the problem]

The means for solving the above-mentioned problems are shown in FIGS. 1A and 1B.

In FIG. 1A, a piezo-type injection valve 9 for a diesel engine is used.
A driving device for the sub-injection drive and the main injection drive, wherein the sub-injection high voltage generation circuit 3 is connected to the battery 1 and the first capacitor means 4 is
The sub-injection charge / discharge switching circuit (5, 6, 7, 8) is the first
Is applied to the piezo injector 9. On the other hand, the main injection high voltage generating circuit 3 'is connected to the battery 1, the second capacitor means 4' stores the output of the main injection high voltage generating circuit 3 ', and the main injection charge / discharge switching circuit (5') , 6,7,8) apply the charge of the second condenser means 4 'to the piezo injector 9. And the control circuit 10
Is for controlling the sub-injection charge / discharge switching circuit (5,6,7,8) and the main injection charge / discharge switching circuit (5 ', 6,7,8) to perform sub-injection drive and main injection drive It is.

In FIG. 1B, the main injection for detecting an abnormality of the main injection high-voltage generating circuit 3 'and the main injection charge / discharge switching circuit (5', 6, 7, 8) is added to the components of FIG. 1A. A system abnormality detection circuit 60 (120) is provided, and when the main injection system abnormality detection circuit detects an abnormality in the main injection high voltage generation circuit 3 'or the main injection charge / discharge switching circuit 5', 6, 7, 8 The control circuit 10 performs the main injection drive by controlling the sub-injection charge / discharge switching circuit (5, 6, 7, 8).

(Operation)

According to the means shown in FIG. 1A, the sub-injection and the main injection have separate power supply circuit systems, and even if the injection interval between the sub-injection and the main injection is short, there is no influence between them.

According to the means shown in FIG. 1B, when an abnormality occurs in the power supply circuit system of the main injection, the power supply circuit system of the sub-injection replaces the power supply circuit system of the main injection.

〔Example〕

FIG. 2 is an overall schematic diagram of a diesel engine to which a drive device for a Pied type injection valve for a four-cylinder diesel engine according to the present invention is applied. In FIG. 2, an intake manifold 21 of the diesel engine 20 is provided with an intake pressure sensor 22 for detecting intake air pressure. The intake pressure sensor 22 outputs an analog signal corresponding to the intake pressure to the A / D with a built-in multiplexer of the control circuit 10 in the multiplexer 10.
It is supplied to the converter 101. Further, fuel injection valves 23-1, 23-2, 23-3, 23-4 are provided for each cylinder in the combustion chamber of the engine 20, and these fuel injection valves 23-1, 23-2, 23- 3,23-4
Operate by the expansion and contraction of the piezo elements 24-1, 24-2, 24-3 and 24-4, respectively.

Fuel is supplied from the fuel tank 25 to the combustion injection valves 23-1, 23-2, 23-3, and 23-4 by the fuel pump 26.

The A / D converter 101 of the control circuit 10 includes various sensors such as a water temperature sensor 27 provided in a water jacket of a cylinder block of the engine 20 and an accelerator pedal 28.
An analog signal from the accelerator opening sensor 28 or the like that is linked to a is supplied. Further, the input / output interface 102 of the control circuit 10 is supplied with output signals of the crank angle sensors 29 and 30 for detecting the rotational position of the crankshaft, and one or both of these signals are used as interrupt signals of the CPU 103. Works.

Piezo element 24 of fuel injection valve 23-1,23-2,23-3,23-4
The drive circuit 31 controlled by the control circuit 10 expands and contracts -1,24-2,24-3,24-4.

The control circuit 10 is configured as a microcomputer, for example, and includes an A / D converter 101, an input / output interface 10
2.In addition to the CPU 103, a sub-injection timer 104a, a main injection timer 104b, a ROM 105 for storing program constants and the like, a RAM 106 for storing temporary data and the like, a thyristor firing circuit 107 for controlling the drive circuit 31, and the like. Is provided. Note that the sub injection timer 104a, is set sub injection time T ₁ is, after a lapse of time T _1, the timer 104a is intended for generating the auxiliary injection end interrupt signal to the CPU 103, the main injection timer 104b Is
The main injection time T ₂ is set, after the lapse of time T _2, the timer
104b generates a main injection end interrupt signal to the CPU 103.

32 and 33 are abnormal lamps that are turned on when the drive circuit 31 and the like are abnormal.

FIG. 3 is a detailed circuit diagram of one cylinder of the drive circuit 31 of FIG. 2 as a first embodiment of the present invention. In FIG. 3, the piezo elements 9 correspond to the piezo elements 24-1 to 24-4 in FIG.
It is one of. In FIG. 3, a high voltage generating circuit (flyback type DC / DC converter) 3 ', a capacitor 4', and a charging thyristor 5 'are added to the components shown in FIG. Thus, the high-voltage generating circuit 3, the capacitor 4, the charging thyristor 5, and the coil 6 form a sub-injection dedicated charging circuit, and include the high-voltage generating circuit 3 ', the capacitor 4', the charging thyristor 5 ', and the coil 6. Constitutes a dedicated circuit for charging main injection. The coil 7 and the discharge thyristor 8 are a common discharge circuit for the sub injection and the main injection. Note that the coils 6, 7 and the discharge thyristor 8 can be separately provided for the sub injection and the main injection.

The sub-injection high voltage generation circuit 3 and the main injection high voltage generation circuit 3 'have the same configuration, and the step-up transformer 301 (30
1 '), the switching transistor 302 (30') which turns on and off the current of the primary coil of the step-up transformer 301 (301 ').
2 '), a high-frequency oscillation circuit 303 (303') for turning on and off the switching transistor 302 (302 '), and a positive voltage generated in the secondary coil of the step-up transformer 301 (301'). ') Diode 304 feeding
(304 ').

FIG. 4 is a detailed circuit diagram of one cylinder of the thyristor firing circuit 107 of FIG. That is, the thyristor firing circuit
107 has four monostable multivibrators 401 to 404, 3
Driver circuits 405 to 407 and an OR circuit 408. Here, the monostable multivibrator 401 generates a pulse of a predetermined time width when the sub injection rectangular pulse S ₁ rise, generating a firing signal P ₁ turns on the driver circuit 405. The monostable multivibrator 402 generates a pulse of a predetermined time width when the main injection square pulse S ₂ rise, generating a firing signal P ₂ turns on the driver circuit 406. Furthermore, the monostable multivibrator 403 generates a pulse of a predetermined time width at the time of the fall of the auxiliary injection rectangular pulses S _1, generating a firing signal P ₁ 'to turn on the driver circuit 407 via the OR circuit 408, the monostable multivibrator 404 generates a pulse of a predetermined time width at the time of the fall of the main injection rectangular pulse S _2, to generate a firing signal P ₂ 'to turn on the driver circuit 407 via the OR circuit 407. That is, in FIG. 3, the discharge thyristor 8 is commonly used for the sub-injection and the main injection. Therefore, also in FIG. 4, the OR circuit 408 is provided to share the driver circuit 407 for the sub-injection and the main injection. There is. Note that the driver circuits 405, 406, 407
Is for applying a gate pulse to the gate circuits of the thyristors 5, 5 'and 8, and each monostable multivibrator and the gate circuit of each thyristor are electrically insulated by a pulse transformer.

The times T ₁ , T ₂ and timing of the sub-injection square pulse S ₁ and the main injection square pulse S ₂ in FIG. 4 correspond to the intake pressure sensor 22, the water temperature sensor 27, and the accelerator opening sensor 2 shown in FIG.
8. It is calculated based on signals from the crank angle sensors 29, 30 and the like (see: FIG. 9, FIG. 10, FIG. 11).

The circuit operation of FIGS. 3 and 4 will be described with reference to the timing chart of FIG. In each of the high voltage generating circuits 3 and 3 'of FIG. 3, the transistors 302 and 302' are turned on and off independently by the pulse signals of the oscillating circuits 303 and 303 ', and the primary current flows through the primary coils of the step-up transformers 301 and 301' when the transistors are turned on. Flows, and magnetic energy is accumulated in the air gap. Then, when the transistors 302, 302 'are turned on from off, the magnetic energy charges the capacitors 4, 4' sequentially. In this case, the capacitor voltages V _C , V _C ′ are the maximum voltages E ₁ , E ₂
Which is, for example, E ₁ = E ₂ = 600V.
In other words, charge amounts of Q = C ₁ E ₁ (C ₁ = capacitance of the capacitor 4) and Q = C ₂ E ₂ (C ₂ = capacitance of the capacitor 4 ′) are accumulated in each of the capacitors 4 and 4 ′. .

The sub-injection will be described.
Is charged thyristor 5 as a valve closing signal at a predetermined timing.
On signal P ₁ is generated for. As a result, the charging thyristor 5
Is turned on, so that the capacitor 4, the coil 6,
And the piezo element 9 constitutes an LC resonance circuit, the electric charge of the capacitor 4 is transferred to the piezo element 9, and the driving voltage V _D of the piezo element 9 becomes, for example, E _O = 800V. Turn off by natural translocation.

In above state, after a predetermined period of time T _1, thyristor firing circuit 107
Generates an on signal P ₁ ′ of the discharge thyristor 8 as a valve opening signal, the discharge thyristor 8 is turned on, and therefore, the piezo element 9 and the coil 7 constitute an LC resonance circuit, and the electric charge of the piezo element 9 is discharged. , the drive voltage V _D of the piezoelectric element 9, for example, after a -200 V, the discharge thyristor 8 is turned off by the current natural commutation.

Explaining in the main injection, the thyristor firing circuit 107
There ON signal P ₂ of the charging thyristor 5 'as closing signal at a predetermined timing is generated. At this point, since the high voltage generation circuit for the sub injection and the high voltage generation circuit for the main injection are independent, the capacitor voltage V _C ′ has already reached its maximum voltage E ₂ . Therefore, the charging thyristor 5 'is turned on, the capacitor 4', the coil 6, and the piezo element 9 constitute an LC resonance circuit, and the electric charge of the capacitor 4 'is transferred to the piezo element 9, and the driving voltage of the piezo element 9 is changed. V _D
For example, after E _O = 800 V, the charging thyristor 5 ′ turns off due to the natural commutation of the current.

In above state, after a predetermined period of time T _2, thyristor firing circuit 107
Generates an on signal P ₂ ′ of the discharge thyristor 8 as a valve opening signal, the discharge thyristor 8 is turned on, and thus the piezo element 9 and the coil 7 constitute an LC resonance circuit, and the electric charge of the piezo element 9 is discharged. is, the driving voltage V _D of the piezoelectric element 9, for example, after a -200 V, the discharge thyristor 8 is turned off by the current natural commutation.

Thus, the capacitor 4, 4 'a high-voltage generating circuit 3, 3 from the battery 1' is raised independently by the impact to be injection interval T ₀ of the auxiliary injection and main injection becomes even shorter Therefore, the target drive voltage can be applied to the piezo element 9, and therefore, the injection rate control can be realized regardless of the rotation speed and the injection timing of the diesel engine. Fuel injection can be performed.

FIG. 6 is a circuit diagram of the drive circuit of FIG. 2 as a second embodiment of the present invention. The high voltage generation circuit 3 'for main injection is provided with an abnormality detection circuit for the components of FIG. 60 is additionally connected. Thereby, when the power supply circuit for main injection fails, the power supply circuit for sub-injection is driven as the main injection to secure the minimum fuel injection function, and therefore, it is possible to continue running. That is, when the main injection power supply circuit drives the piezo-type injection valve when performing the main injection of the diesel engine, if the power transistor or diode constituting the power supply circuit breaks down, the piezo-type injection valve becomes Since the driving voltage of the main injection cannot be applied, the fuel injection is not performed and the vehicle cannot travel. In order to avoid this, an abnormality detection circuit 60 is added to the main injection power supply circuit in addition to the configuration shown in FIG.

The abnormality detection circuit 60 is provided with a voltage detection coil in the step-up transformer 301 ′ of the high voltage generation circuit 3 ′ and is connected via a diode 60 a. A time constant circuit including a capacitor 61 and a discharge resistor 62, a comparator 63, It comprises an RS flip-flop 64, a monostable multivibrator 65, an AND circuit 66, and an RS flip-flop 67. Here, the flip-flop 64 is for detecting that the high-voltage generating circuit 3 'itself is abnormal, and the flip-flop 67 is for detecting that there is no abnormality in the high-voltage generating circuit 3' itself. This is for detecting the thyristor 5 ′, the piezo element 9, and abnormalities around them. Further, the monostable multivibrator 65 and the AND circuit 66 are for setting the operation cycle of the flip-flop 67.

In the flyback type DC / DC converter 3 'shown in FIG.
When the transistor 302 'is energized and a current flows through the primary coil, magnetic energy is stored in the air gap of the step-up transformer 301', and the capacitor 4 'and the abnormality detection capacitor 61 are sequentially charged.

First, the normal state will be described with reference to FIG. 7. A part of the electric charge stored in the capacitor 4 'is supplied to the piezo element 9 at the timing of starting the main injection.
On the other hand, the abnormality detecting capacitor 61 the charge at the initial time is not stored, the detected voltage V _m is increased as indicated by X ₁ in FIG. 7. As a result, the comparator 63 is the detection voltage V _m, V _m> V
If outputs a high level ( "1") when _R1, and outputs a low level when the _{V m ≦ V R1 ( "0} "), the comparator 63
Output V _X becomes "1", the flip-flop 64 is set, its output Q1 goes high. On the other hand, the flip-flop 67, since the operation by the output V _X of the comparator 63 for the period by the output of the monostable multivibrator 65 corresponding to the rising edge of the main injection square pulse T _2, there in this case, V _m <V _R1 Therefore, flip-flop 67 is not set. That is, the output states of the two flip-flops 64 and 67 are It is.

On the other hand, the open failure of the thyristor 5 'and the piezo element 9
In the event of an abnormality on the side of the piezo-type injection valve such as disconnection of the wire harness up to this point or an open defect of the piezo element 9 (abnormal state I), the electric charge stored in the capacitor 4 'is not supplied to the piezo element 9 but remains there. Since no charge is stored in the abnormality detection capacitor 61, the detection voltage _Vm is equal to X _{2 in} FIG.
As shown in the figure rises sharply. As a result, similarly to the normal state, but the flip-flop 64 is set, the output V _X also V _m> V _R1 next to comparator 65 even when the output of the monostable multivibrator 65, thus, the flip-flop 67 is also set You. That is, the output states of the two flip-flops 64 and 67 are Becomes

In such an abnormal state I, the control circuit 10
As shown in the figure, the operation of the high voltage generation circuits 3, 3 'is stopped, and the capacitors 4, 4' are discharged to notify the driver of the abnormality.

Further, the transistor 302 'bad open, the diode 304', when the main injection power circuit side of the short circuit or the like 60a abnormality (an abnormal state II), the capacitor voltage V _C 'and as shown in FIG. 8 The detection voltage _Vm does not increase at all.
As a result, neither of the flip-flops 64 and 67 is set. That is, the output states of the two flip-flops 64 and 67 are Becomes

In such an abnormal state II, the control circuit 10
As shown in the figure, the capacitor 4 'is discharged to switch from the dual power supply system to the single power supply system. That is, the sub injection rectangular pulses S ₁ and main injection rectangular pulse S _2, stops the output of the original main injection square pulse S _2.

As described above, according to the drive circuit of FIG. 6, the main injection side circuit is monitored, and the two flip-flops 64 and 67 Abnormal states I and II can be detected, which makes it possible to deal with abnormal states.

The reset signal RST for shifting the flip-flops 64 and 67 to the monitoring mode is generated at the timings shown in FIGS.

9 to 11 are flowcharts showing the operation of the control circuit (microcomputer) 10 for operating the drive circuit of FIG.

FIG. 9 shows the main routine. In step 901,
Initialization For example, the injection time data and the like stored in the RAM 106 are initialized, and at the same time, the injection timer and the like are initialized.
In step 902, takes the output of such an intake air pressure sensor 22 converts A / D, based on these data in step 903 to 904 sub injection start timing P ₁ and the sub-injection time T _1, the main injection start timing P ₂ and calculates the main injection time T _2.

The sub-injection timer 104a and the main injection timer 104b are based on a reference signal and an angle signal input from a crank angle sensor.
It counts and outputs the injection square pulses S ₁ and S ₂ to the I / O 102 and generates an injection end interrupt timing. When the control circuit 10 is first started, the injection timers 104a and 104b are set in step 901 of the main routine.

As described above, when the sub-injection timer 104a and the main-injection timer 104b are set and timed up, the CP
An interrupt occurs in U103.

FIG. 10 shows a sub-injection end interrupt routine executed when the sub-injection timer 104a times out. Step 10
At 01, the outputs Q1 and Q2 of the flip-flops 64 and 67 are fetched, and at step 1002, the reset signal RST is transmitted to execute the next monitoring mode, and the flip-flops 64 and 67 are reset.

In steps 1004 and 1005, the states of the outputs Q1 and Q2 of the flip-flops 64 and 67 are determined. As a result, Q1 = "H" and Q2 = "L"
If so, the main injection system is in a normal state, and the flow advances to step 1005 to set the sub-injection data (sub-injection start timing P ₁ , sub-injection time T ₁ ) of the next cycle in the sub-injection timer 104a, and in step 1006 The sub-injection end interrupt routine ends.

If Q1 = "H", Q2 = "H", it is an abnormality of the injection valve system (abnormal state I described above).
Turn on 32 and light up, and in step 1008 high voltage generation circuit
Prohibit charging of capacitors 4 and 4 'by 3,3' and step
After discharging the capacitors 4, 4 'in 1009, the control is ended in step 1010. Similarly, if Q1 = “L”, the power supply system for main injection is abnormal (abnormal state II described above), so the abnormal lamp 33 is turned on and lit in step 1011, and the next cycle is performed in step 1012. After the injection switching operation is performed by setting the main injection data (main injection start timing P ₂ , main injection time T ₂ ) in the sub injection timer 104a, Step 10
At 13, the sub-injection end interrupt routine ends.

FIG. 11 shows a sub-injection end interrupt routine executed when the main injection timer 104b times out. That is,
In step 1101, the state of the output Q1 of the flip-flop 64 is determined. As a result, if Q1 = “H”, the main injection system is in a normal state, so the process proceeds to step 1102, where the main injection data (main injection start timing P _2, the main injection time T ₂₎
Is set in the main injection timer 104b, and the main injection end interrupt routine ends in step 1104.

If Q1 = “L”, the main injection power supply system is abnormal (abnormal state II described above), so in step 1103, the main injection timer 104b is stopped, and the routine proceeds to step 1104 to end this routine.

In this manner, the function of notifying the driver of the abnormality by the abnormal lamps 32 and 33 is provided, and when the main injection power supply circuit system is abnormal, the main injection drive of the piezo element 9 is performed by using the sub injection power supply system. continue. As a result, the minimum fuel injection function can be ensured, and temporary traveling to a repair shop or the like is possible.

FIG. 12 is a circuit diagram of the drive circuit of FIG. 2 as a third embodiment of the present invention. An abnormality detection circuit 120 is provided instead of the abnormality detection circuit 60 of FIG.

The abnormality detection circuit 120 shown in FIG.
201, transformer 1202, diode 1203, coil 120
4, capacitor 1205, discharge resistor 1206, comparator 1207, and R
It is composed of an S flip-flop 1208. In other words, if normal, the detected current i _s is detected the time constant circuit (120
5,1206) is charged, by monitoring whether exceeds a predetermined value V _R2 by comparator 1207 the output, can detect an abnormality of the main injection for power supply system.

The circuit operation of FIG. 12 will be described with reference to FIGS. 13 and 14. The primary coil of the capacitor 1201 and the transformer 1202 in the timing of ignition of the charge thyristor 5 '(main injection start), the detected current i _s as Fig. 13 flows. The detection current i _s detected by the secondary coil of the transformer 1202, a diode 1203, to charge the capacitor 1205 via the coil 1204. The potential of the capacitor 1205 is increased if normal, it is detected that reaches a predetermined potential V _R2 comparator 1207. Therefore, flip-flop 1208 is set and the control circuit
10 monitors this output Q3.

On the other hand, when there is an abnormality in the main injection power supply circuit such as an open defect of the transistor 302 'or a short circuit of the diode 304', the detection current is detected at the timing of firing of the thyristor 5 '(main injection start) as shown in FIG. i _s does not flow, therefore, the flip-flop 1208 of the abnormality detection circuit 120 is not set. After monitoring the output Q3 of the flip-flop 1208 at the timing of the sub-injection in a similar routine as shown in FIG. 10 by the control circuit 10, the flip-flop 1208 is not set because it is always reset. In this case, it can be determined that the main injection power supply circuit has failed. That is, the same main injection (time T ₂ ) as in the second embodiment
Can be performed by the sub-injection system.

9 to 11 can also be applied to the third embodiment. In this case, since there is only one kind of abnormal state, the steps 1003 to 1013 in FIG. To determine if the output Q3 is “L” (abnormal state)
If Q3 = "L", perform steps 1011 to 1013, and Q3 = "H"
In this case, steps 1005 to 1006 may be performed.

〔The invention's effect〕

As described above, according to the present invention, the sub-injection and the main injection have separate power supply circuit systems, and even if the injection interval between the sub-injection and the main injection is short, there is no influence between them. Thus, stable fuel injection can be achieved. Further, even if the drive circuit of the main injection system becomes abnormal, the main injection is performed by the drive circuit of the sub-injection system.

[Brief description of the drawings]

1A and 1B are block diagrams showing a basic configuration of the present invention, FIG. 2 is an overall schematic diagram of a diesel engine to which a piezo-type injection valve for a diesel engine of the present invention is applied, and FIG. 2 is a detailed circuit diagram of the drive circuit of FIG. 2 as a first embodiment, FIG. 4 is a detailed circuit diagram of a thyristor ignition circuit of FIG. 2, FIG. 5 is a circuit of FIG. 3 and FIG. FIG. 6 is a detailed circuit diagram of the drive circuit of FIG. 2 as a second embodiment of the present invention, and FIGS. 7 and 8 are timing diagrams showing the circuit operation of FIG. 9 to 11 are flowcharts showing the operation of the control circuit in the second embodiment. FIG. 12 is a detailed circuit diagram of the drive circuit in FIG. 2 as a third embodiment of the present invention. 13 and 14 are timing diagrams showing the circuit operation of FIG. 12, and FIG. 15 is a diagram of a conventional piezo-type injection valve for a diesel engine. 16, 17 are diagrams showing the circuit operation of FIG. 15, FIG. 18 is a circuit diagram of a conventional piezo-type injector driving device for a diesel engine, FIG. 19 is FIG. FIG. 4 is a timing chart showing the circuit operation of the figure. 1 ... battery, 2 ... key switch, 3, 3 '... high voltage generation circuit, 5, 5' ... charge thyristor, 8 ... discharge thyristor, 10 ... control circuit, 60,120 ... abnormality detection circuit.

Continuation of the front page (72) Inventor Yasufumi Yamada 1-1-1, Showa-cho, Kariya-shi, Aichi, Japan Inside Denso Corporation (72) Inventor Keizo Natsume 1-1-1, Showa-cho, Kariya-shi, Aichi Japan Inside Denso Corporation ( 72) Inventor Naoyuki Tsuzuki 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (56) References JP-A-61-241438 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB Name) F02D 1/00-1/14 F02D 41/00-41/40 F02M 51/06

Claims (2)

(57) [Claims] A driving device for a sub-injection drive and a main injection drive of a piezo type injection valve (9) for a diesel engine, wherein a high voltage generation circuit (3) for a sub-injection is connected to a battery (1). A first capacitor means (4) for accumulating an output of the sub-injection high voltage generation circuit; and a charge / discharge switching circuit for sub-injection (5) for applying a charge of the first capacitor means to the piezo type injection valve. , 6,7,8)
A high voltage generation circuit for main injection (3 ') connected to the battery; a second capacitor means (4') for accumulating an output of the high voltage generation circuit for main injection; and a second capacitor means Charge / discharge switching circuit (5 ', 6,7,7) for applying the electric charge to the piezo-type injection valve.
8) and a control circuit (10) that controls the sub-injection charge / discharge switching circuit and the main-injection charge / discharge switching circuit to control the injection interval in the sub-injection drive and the main injection drive, respectively. Drive system for piezo-type injection valves for diesel engines. A main injection system abnormality detecting circuit for detecting an abnormality of the main injection high voltage generating circuit or the main injection charging / discharging switching circuit; The control circuit performs the main injection drive by controlling the sub-injection charge / discharge switching circuit when an abnormality of the main injection high voltage generation circuit or the main injection charge / discharge switching circuit is detected. 2. The driving device according to 1.