Injector driving circuit

• US 4,377,144 A
• Filed: 09/03/1981
• Issued: 03/22/1983
• Est. Priority Date: 09/08/1980
• Status: Expired due to Term

• Current Assignee: Tokyo Shibaura Denki Kabushiki Kaisha (Toshiba Corporation)
• Original Assignee: Tokyo Shibaura Denki Kabushiki Kaisha (Toshiba Corporation)
• Inventors: Takahashi, Yukiharu
• Primary Examiner(s): Cox, Ronald B.
• Application Number:
  US06/299,135
• Time in Patent Office: 565 Days
• Field of Search: 123/490, 361/152, 361/153, 361/154
• US Class Current: 123/490
• CPC Class Codes: F02D 2041/2006 by using a boost capacitor
• CPC Class Codes: F02D 2041/2017 using means for creating a boost current or using reference switching
• CPC Class Codes: F02D 2041/2058 using information of the actual current value
• CPC Class Codes: F02D 41/20 Output circuits, e.g. for controlling currents in command coils
• CPC Class Codes: H03K 17/64 having inductive loads

Abstract

An injector driving circuit includes a first diode forwardly coupled between one end of a solenoid coil and a positive power supply terminal, a capacitor with one end grounded, a second diode forwardly coupled between the other end of the coil and the capacitor with respect to the positive power supply terminal, a switching transistor coupled between the other end of the coil and the ground and connected to be turned on in response to a driving input signal, a current detecting circuit for detecting current flowing through the coil and producing an output signal when detecting that the coil current has reached a predetermined value, and a switching circuit coupled between the one end of the coil and the other end of the capacitor and connected to be closed and opened in response to the driving input signal and the output signal of the current detecting circuit, respectively.

Claims

1. An injector driving circuit comprising:

a power supply voltage terminal and a reference voltage terminal;

a first diode circuit coupled between one end of a solenoid coil of an injector to be driven and said power supply voltage terminal to supply said one end of said solenoid coil with a power supply voltage applied to said power supply voltage terminal;

first switching means coupled between the other end of said solenoid coil and said reference voltage terminal to control the current conducting state of said solenoid coil in accordance with a driving input signal;

current detecting means producing an output signal when detecting that current flowing through said solenoid coil has reached a predetermined value;

charge storing means with one end coupled to said reference voltage terminal;

second switching means coupled between said one end of said solenoid coil and the other end of said charge storing means and connected to be turned on and off in resonse to the driving input signal and the output signal from said current detecting means, respectively; and

a second diode circuit coupled between said other end of said solenoid coil and said other end of said charge storing means to allow current to flow from said solenoid coil to said charge storing means.

2. An injector driving circuit according to claim 1, further comprising a Zener diode whose cathode is coupled to said other end of said charge storing means and whose anode is coupled to said reference voltage terminal.

3. An injector driving circuit according to claim 1 or 2, further comprising a third diode circuit coupled between said power supply voltage terminal and said other end of said charge storing means to supply said other end of said charge storing means with the power supply voltage applied to said power supply voltage terminal.

4. An injector driving circuit according to claim 1 or 2, wherein said current detecting means includes a resistor coupled in series with said solenoid coil and a comparing circuit producing an output signal when a voltage drop at said resistor reaches a predetermined voltage level.

5. An injector driving circuit according to claim 4, wherein said second switching means includes a flip-flop circuit producing a first output signal in response to the driving input signal and producing a second output signal in response to the output signal from said comparing circuit, and a switching circuit turned on and off in response to said first and second output signals from said flip-flop circuit, respectively.

6. An injector driving circuit comprising:

a power supply voltage terminal and a reference voltage terminal;

a plurality of first diode circuits coupled between respective one ends of solenoid coils of a plurality of injectors to be driven and said power supply voltage terminal to supply said one ends of said solenoid coils with a power supply voltage applied to said power supply voltage terminal;

a plurality of first switching means coupled between the respective other ends of said solenoid coils and said reference voltage terminal to control the current conducting state of said solenoid coils in accordance with a driving input signal;

a plurality of current detecting means each producing an output signal when detecting that current flowing through its corresponding one of said plurality of solenoid coils has reached a predetermined value;

charge storing means with one end coupled to said reference voltage terminal;

a plurality of second switching means respectively coupled between said one ends of said solenoid coils and the other end of said charge storing means and connected to be turned on and off in response to the driving input signal and the output signals from said current detecting means, respectively; and

a plurality of second diode circuits respectively coupled between said other ends of said solenoid coils and said other end of said charge storing means to allow current to flow from said solenoid coil to said charge storing means.

7. An injector driving circuit according to claim 6, further comprising a Zener diode whose cathode is coupled to said other end of said charge storing means and whose anode is coupled to said reference voltage terminal.

8. An injector driving circuit according to claim 6 or 7, further comprising a third diode circuit coupled between said power supply voltage terminal and said other end of said charge storing means to supply said other end of said charge storing means with the power supply voltage applied to said power supply voltage terminal.

9. An injector driving circuit according to claim 6 or 7, wherein each of said current detecting means includes a resistor coupled in series with said solenoid coil and a comparing circuit producing an output signal when a voltage drop at said resistor reaches a predetermined voltage level.

10. An injector driving circuit according to claim 9, wherein each of said second switching means includes a flip-flop circuit producing a first output signal in response to the driving input signal and producing a second output signal in response to the output signal from said comparing circuit, and a switching circuit turned on and off in response to said first and second output signals from said flip-flop circuit, respectively.