JP2003161193A - Booster circuit for injector drive of automobile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a booster circuit which drives an injector by a stipulated voltage. <P>SOLUTION: A plurality of capacitors storing a boosting voltage are prepared and one of the capacitors is used for driving an injector every time injection is performed, whereas the other capacitors are charged to prepare for next injection. Therefore, a full charged capacitor can be used even if the time interval is short between a first injection and second injection, so that the injector is driven by the stipulated voltage. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a booster circuit used for driving an injector of a vehicle.

[0002]

2. Description of the Related Art As a conventional technique, when a battery voltage (VB) is boosted by using a boosting circuit and an injector is driven by using the boosted voltage, one injector for each cylinder is used for boosting. Was driving.

[0003]

In the above prior art, when the boosted voltage drops once the injection is performed and the next injection comes earlier than the recovery time of the boosted voltage, the injector is driven while the boosted voltage remains low. Therefore, there is a problem that the injector cannot be opened and the flow rate of the injector cannot be accurately measured.

[0004]

The above problems can be solved by the inventions described in the claims. For example, it has multiple capacitors to store boosted voltage, one capacitor is used to drive the injector for each injection, the other capacitors are charged, and the first and second injections are prepared by preparing for the next injection. Even if the interval is short, a fully charged capacitor can be used, so the injector can be driven at a specified voltage.

Further, a plurality of capacitors for storing the boosted voltage are provided, one capacitor is used for driving the injector for each injection, and the other capacitors are charged to prepare for the next injection, thereby preparing the first injection and the second injection. Even if the injection interval of the second injection is short, the fully charged capacitor can be used, so the injector can be driven with the specified voltage.

Therefore, the injector can be reliably opened,
The flow rate of the injector can be measured accurately.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below. FIG. 5 is an embodiment of claims 1 and 2.

FIG. 6 is a timing chart of each part.
FIG. 7 shows another embodiment of claims 1 and 2. FIG. 8 is a timing chart of each part of FIG.

FIG. 9 is a block diagram of a switching circuit used in the present invention.

Before describing the present invention, an outline of the injector drive circuit will be described.

FIG. 1 is a block diagram of a conventional injector drive circuit. FIG. 2 is an injector current control operation waveform (timing chart).

Reference numeral 1 is a booster circuit for supplying a valve opening current.
2 is a FET for driving the valve opening current. FE for holding current drive
T. 4 is an injector. Reference numeral 5 is a FET for energizing the injector downstream side. 6 is a current detection resistor for detecting the current flowing through the injector. 7 is a control unit for controlling the current. Reference numeral 8 is a fuel injection signal.

When the fuel injection signal of 8 becomes H (thick line in the timing chart), the FET of 2 is turned on and a current is rapidly supplied from the booster circuit of 1 to the injector.

At the same time, the FET on the downstream side of 5 is turned on from off. FE of 2 when the injector current reaches Iph
Turn off T. Off period 4, 5, 6 diode D
The current flows back through the path of the 3,4 injector. The injector current is detected by the current detection resistor 6 and the holding current Ihl is detected.
In the following cases, the holding drive FET 3 is turned on. When the holding current exceeds Ihh, the holding driving FET 3 is turned off. During the off period, current is circulated in the path of the 4,5,6 diode D3,4 injector. Similarly, the current of the injector is controlled to be between Ihh and Ihl. When the fuel injection signal of 8 becomes L (timing chart thin line), the holding drive FET of 3 and the downstream drive FE
Turn off T5 and zero injector current.

The problems of the conventional circuit will be described with reference to FIGS.

In FIG. 3, 11 is a boost coil, 10 is a boost control FET, 12 is a reverse current blocking diode, 13 is a boost capacitor, 14 is a boost circuit, and 9 is a valve opening current control SW1.
SW4, 15 to 18 are injectors 1 to 4. In the case of four cylinders, the valve opening current control is shown. The holding current control and a specific current control circuit are omitted.

In the booster circuit of 14, the current of the coil of 11 is turned on and off by the FET of 10 so that the target voltage VH is obtained by the divided voltage of the capacitor of 13 and the reference voltage Vref. 13 capacitors are charged via.

The injection signal shown in FIG. 4 shows the case of divided injection because one injection signal is divided and added to the injector. The case of INJ1 injection will be described as an example.

The boosted voltage decreases due to the first-half injection. If the latter half of the injection signal is input before the boosted voltage is restored, the rising gradient of the valve opening current becomes gentle due to the shortage of the boosted voltage, and the time for reaching the specified current value becomes long. If the undervoltage becomes too large, it will not be possible to open the injector, and the fuel measurement will vary.

5 and 6 show an embodiment of the present invention.

Reference numeral 19 is an additional reverse current blocking diode, 20
Is a boosting capacitor added, 21 is a boosting capacitor switching SW, and 22 to 23 are reverse current blocking diodes.

It is assumed that the capacitors 13 and 20 are charged to a specified voltage before the injection signal is input.

In the first half of the INJ1 injection signal, it is assumed that 13 capacitors are connected to the VH line by SW11. When the injection signal is input, SW1 is turned on. The injector valve opening current is passed by the condenser of 13. After reaching the specified current, SW1 is closed. The capacitor 13 changes from discharging to charging. After the injection in the first half, the capacitor 20 after the injection is connected to the VH line by the SW12 to prepare for the latter injection. SW11 is turned off. The capacitor 13 is continuously charged.

SW1 at which the latter half of the injection is started is turned on. A valve opening current is passed through the injector by means of the capacitor 20. After reaching the specified current, SW1 is closed. The capacitor of 20 changes from discharging to charging. Since there is only one booster circuit, 20 capacitors with low voltage are mainly charged. When the capacitor voltage of 13 and the capacitor voltage of 20 become the same, the capacitors 13 and 20 are charged evenly. Below I
The NJ2, 3, 4, 1 injection signal is repeatedly operated.

FIG. 9 shows a switching circuit for the capacitor switching SW 21. The respective injection signals are ORed. Injection signal O
The capacitor is switched at the falling edge of R.

It is possible to prepare for the next injection by switching at the trailing edge.

When there is no time delay in switching the capacitor, switching may be performed at the rising edge of the injection signal.

7 and 8 show another embodiment of the present invention.

Reference numeral 24 is an additional boosting coil, 25 is an additional boosting control FET, 26 is a reverse current blocking diode, 2
Reference numeral 7 indicates the added booster circuit 2.

This is the case where the booster circuit has two systems. This is a case where the booster circuit 1 further shares the 13 capacitors and the booster circuit 1 shares the 20 capacitors, thereby further increasing the boost drive capability.

It is assumed that the capacitors 13 and 20 are charged to a specified voltage before the injection signal is input.

In the first half of the INJ1 injection signal, it is assumed that 13 capacitors are connected to the VH line by SW11. When the injection signal is input, SW1 is turned on. The injector valve opening current is passed by the condenser of 13. After reaching the specified current, SW1 is closed. The capacitor 13 changes from discharging to charging. After the injection in the first half, the capacitor 20 after the injection is connected to the VH line by the SW12 to prepare for the latter injection. SW11 is turned off. The capacitor 13 is continuously charged.

SW1 at which the latter half of the injection is started is turned on. A valve opening current is passed through the injector by means of the capacitor 20. After reaching the specified current, SW1 is closed. The capacitor of 20 changes from discharging to charging. 1 because the booster circuit is independent
Charging of capacitor 3 is charged independent of the capacitor voltage of 20. Further, the 20 capacitors can be charged without being affected by the 13 voltage. Therefore, the charging time is shortened and the driving ability is improved. Below I
The NJ2, 3, 4, 1 injection signal is repeatedly operated.

FIG. 9 shows a switching circuit of the capacitor switching SW 21.

The respective injection signals are ORed. OR of injection signals
Switch the capacitor at the falling edge of.

It is possible to prepare for the next injection by switching at the trailing edge.

If there is no time delay in switching the capacitor, switching may be performed at the rising edge of the injection signal.

[Brief description of drawings]

FIG. 1 is a block diagram of an injector drive circuit.

FIG. 2 is an injector current control operation waveform and timing chart.

FIG. 3 is a conventional booster circuit.

FIG. 4 is a conventional booster circuit operation waveform and timing chart.

FIG. 5 is a block diagram of a booster circuit according to the present invention.

FIG. 6 is a timing chart of a booster circuit operation waveform of the present invention.

FIG. 7 is a block diagram of a booster circuit according to another embodiment of the present invention.

FIG. 8 shows another embodiment of the present invention, a booster circuit operation waveform, and a timing chart.

FIG. 9 is a capacitor switching circuit of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Boost circuit, 2 ... FET for driving valve opening current, 3 ... FET for driving holding current, 4 ... Injector, 5 ... FET for downstream side energization, 6 ... Current detection resistor, 7 ... Current control circuit, 8 ... Fuel injection Signals, 9 ... Valve opening current control SW1 to SW4, 10 ...
Boosting FET, 11 ... Boosting coil, 12, 26 ... Reverse current blocking diode, 13 ... Boosting capacitor, 14 ... Boosting circuit 1, 15-18 ... Injectors 1-4, 19 ... Additional reverse current blocking diode, 20 ... Additional boosting Capacitors, 2
1 ... Capacitor switching SW11, SW12, 22, 23
… Reverse current blocking diode, 24… Additional boost coil, 25
... additional boosting FET, 27 ... additional boosting circuit, 28 ... switching circuit.

Continued front page    (72) Inventor Yoshiyuki Akiyama             Hitachinaka City, Ibaraki Prefecture 2520 Takaba             Ceremony Company Hitachi Ltd. Automotive equipment group (72) Inventor Yuichi Kashimura             Hitachinaka City, Ibaraki Prefecture 2520 Takaba             Ceremony Company Hitachi Ltd. Automotive equipment group F term (reference) 3G066 AB02 CC06U CE22 CE29                       DA01 DA04                 3G301 JA03 LC01 LC10 MA11

Claims (3)

[Claims] 1. A step-up circuit used for driving an injector of a vehicle, comprising a plurality of step-up circuits, one step-up circuit for each injection is used to drive the injector, and another step-up circuit charges a capacitor. A booster circuit for driving an injector of a vehicle, which is prepared for the next injection. 2. A booster circuit used for driving an injector of a vehicle, comprising a plurality of capacitors for storing boosted voltage, one capacitor is used for driving the injector for each injection, and another capacitor is charged to A booster circuit for driving an injector of an automobile, which is equipped for injection. 3. The cylinder according to claim 1 or 2, wherein a certain cylinder is 2
A booster circuit for driving an injector of an automobile that can drive the injector at a specified voltage even when continuous injection is performed by stage injection (split injection).