Inductive discharge injector driver

• US 5,979,412 A
• Filed: 08/12/1997
• Issued: 11/09/1999
• Est. Priority Date: 08/12/1997
• Status: Expired due to Fees

• Current Assignee: Walbro Engine Management LLC (Sun Capital Partners Incorporated)
• Original Assignee: Walbro Corporation (Sun Capital Partners Incorporated)
• Inventors: Werner, Matthew L.
• Primary Examiner(s): Wolfe, Willis R.
• Assistant Examiner(s): GIMIE, MAHMOUD
• Application Number:
  US08/909,964
• Time in Patent Office: 819 Days
• Field of Search: 123/490, 327/110, 327/326, 327/434, 307/104, 361/155, 361/156
• US Class Current: 123/490
• CPC Class Codes: F02D 2041/2003 using means for creating a boost voltage, i.e. generation or use of a voltage higher than the battery voltage, e.g. to speed up injector opening
• CPC Class Codes: F02D 2041/201 by using a boost inductance
• CPC Class Codes: F02D 2041/389 for injecting directly into the cylinder
• CPC Class Codes: F02D 2200/0406 Intake manifold pressure
• CPC Class Codes: F02D 2200/0414 Air temperature
• CPC Class Codes: F02D 41/20 Output circuits, e.g. for controlling currents in command coils

Abstract

A drive circuit for energizing an engine fuel injector coil from a power source which has energy storage means responsive to a first control signal for selectively storing energy from the power source, and means responsive to a second control signal for selectively discharging energy stored in the energy storage means into said injector coil. The stored energy is discharged into the injector coil in addition to energy from the power source, to more rapidly open the fuel injector. In a preferred embodiment, the circuit has an inductor in circuit with the fuel injector, an inductor driver switch to control the flow of current through the inductor and an injector driver switch to control the flow of current through the fuel injector. When the inductor is energized by its associated switch, it stores significant electromagnetic energy therein, which is transferred to the injector when it is desired to open the injector to deliver an increased current to the injector to more quickly open it and reduce the start delay time for the injection event.

Claims

1. A drive circuit for energizing an engine fuel injector coil from a power source, comprising:

energy storage means responsive to a first control signal for selectively storing energy from the power source, wherein said energy storage means includes an inductor and a first switch that is responsive to the first control signal to draw current through the inductor from the energy source; and

switch means responsive to a second control signal for selectively discharging energy stored in the energy storage means into the injector coil, wherein said switch means includes a switch for connecting in series with the injector coil to control the flow of current from the power source and said inductor through the injector coil;

wherein said inductor has a resistance of less than about 5 ohms and an inductance of about between 5 to 20 mHenry'"'"'s.

2. A drive circuit for energizing an engine fuel injector coil from a power source, comprising:

energy storage means responsive to a first control signal for selectively storing energy from the power source, wherein said energy storage means includes an inductor and a first switch that is responsive to the first control signal to draw current through the inductor from the energy source; and

switch means responsive to a second control signal for selectively discharging energy stored in the energy storage means into the injector coil, wherein said switch means includes a switch for connecting in series with the injector coil to control the flow of current from the power source and said inductor through the injector coil;

wherein said inductor has a resistance of between about 0.1 and 0.05 that of the injector coil.

3. A drive circuit for energizing an engine fuel injector coil from a power source, comprising:

an energy storage device for coupling to the power source to store energy when current from the power source flows through the storage device;

a first switch coupled to the storage device, said first switch having a conductive state which permits current flow through said first switch and having a non-conductive state which prevents current flow through said first switch;

a second switch for switching current through the injector coil, said second switch having a conductive state which permits current flow through said second switch and having a non-conductive state which prevents current flow through said second switch;

an electronic control unit having a first output coupled to said first switch and a second output coupled to said second switch, said microprocessor providing a first control signal on said first output to place said first switch in either said conductive or non-conductive states and providing a second control signal on said second output to place said second switch in either said conductive or non-conductive state;

wherein, when said drive circuit is connected to the power source and injector coil;

said first switch is operable in its conductive state to draw current through said energy storage device to thereby store energy in said storage device;

said second switch is operable in its conductive state to draw current through the injector coil; and

said storage device is coupled to the injector coil to supply its stored energy to the injector coil when said first switch is in its non-conductive state and said second switch is in its conductive state;

wherein said microprocessor is operable to place said first switch in its conductive state and said second switch in its non-conductive state to thereby store energy in said storage device, and wherein said microprocessor is operable to then switch said second switch to its conductive state and to thereafter switch said first switch to its non-conductive state, whereby said second switch is placed in its conductive state prior to discharging of energy stored in said storage device.

4. A drive circuit as defined in claim 3, wherein said storage device comprises an inductor.

5. A drive circuit as defined in claim 4, wherein said inductor has a resistance of between about 0.1 to 0.05 that of the injector coil.

6. A drive circuit as defined in claim 4, further comprising a current steering diode connected in circuit to provide a current path in parallel with said inductor.

7. A drive circuit as defined in claim 4, wherein said first and second switches comprise MOSFETs.

8. A drive circuit for energizing an engine fuel injector coil from a power source, comprising:

an energy storage device for coupling to the power source to store energy when current from the power source flows through the storage device;

a first switch coupled to the storage device, said first switch having a conductive state which permits current flow through said first switch and having a non-conductive state which prevents current flow through said first switch;

a second switch for switching current through the injector coil, said second switch having a conductive state which permits current flow through said second switch and having a non-conductive state which prevents current flow through said second switch;

an electronic control unit having a first output coupled to said first switch and a second output coupled to said second switch, said microprocessor providing a first control signal on said first output to place said first switch in either said conductive or non-conductive states and providing a second control signal on said second output to place said second switch in either said conductive or non-conductive state;

wherein, when said drive circuit is connected to the power source and injector coil;

said first switch is operable in its conductive state to draw current through said energy storage device to thereby store energy in said storage device;

said second switch is operable in its conductive state to draw current through the injector coil; and

said storage device is coupled to the injector coil to supply its stored energy to the injector coil when said first switch is in its non-conductive state and said second switch is in its conductive state;

wherein, when said drive circuit is connected to the power source and injector coil, said microprocessor is operable to place said first switch in its conductive state and said second switch in its non-conductive state to thereby store energy in said storage device, and wherein said microprocessor is operable to then switch said second switch to its conductive state and said first switch to its non-conductive state to thereby discharge energy stored in said storage device into the injector coil and further, wherein said microprocessor is operable to de-energize the injector coil by switching said first switch to its conductive state, switching said second switch to its non-conductive state, and thereafter switching said first switch back to its non-conductive state.

9. A drive circuit as defined in claim 8, wherein said storage device comprises an inductor.

10. A drive circuit as defined in claim 9, wherein said inductor has a resistance of between about 0.1 to 0.05 that of the injector coil.

11. A drive circuit as defined in claim 9, further comprising a current steering diode connected in circuit to provide a current path in parallel with said inductor.

12. A drive circuit as defined in claim 9, wherein said first and second switches comprise MOSFETs.