Apparatus and method for electronically reducing the impact of an armature in a fuel injector

• US 6,128,175 A
• Filed: 03/25/1999
• Issued: 10/03/2000
• Est. Priority Date: 12/17/1998
• Status: Expired due to Term

• Current Assignee: Continental Automotive Systems, Inc. (Continental AG)
• Original Assignee: Siemens Automotive Corporation (Siemens AG)
• Inventors: Czimmek, Perry Robert, Wright, Danny Orlen
• Primary Examiner(s): Jackson, Stephen W.
• Application Number:
  US09/276,224
• Time in Patent Office: 558 Days
• Field of Search: 361/154, 361/187, 361/167, 361/160, 361/143, 361/144, 361/191
• US Class Current: 361/154
• CPC Class Codes: F02D 2041/2017 using means for creating a boost current or using reference switching
• CPC Class Codes: F02D 2041/2034 Control of the current gradient
• CPC Class Codes: F02D 2041/2037 for preventing bouncing of the valve needle
• CPC Class Codes: F02D 2041/2051 using voltage control
• CPC Class Codes: F02D 2041/2055 with means for determining actual opening or closing time
• CPC Class Codes: F02D 41/20 Output circuits, e.g. for controlling currents in command coils
• CPC Class Codes: H01F 2007/1894 minimizing impact energy on closure of magnetic circuit
• CPC Class Codes: H01F 7/18 Circuit arrangements for obtaining desired operating characteristics, e.g. for slow operation, for sequential energisation of windings, for high-speed energisation of windings

Abstract

A method is provided to control velocity of an armature of a fuel injector as the armature moves from a first position towards a second position. The fuel injector includes a stator core at the second position and a coil is associated with the stator core. The coil, the stator core and the armature define a magnetic circuit. The coil generates a magnetic force to cause the armature to move towards and impact the stator core. The method includes energizing the coil to permit the armature to move towards the stator core. A rate of change of magnetic flux of the magnetic circuit is determined. Closed loop feedback control of the determined rate of change of magnetic flux is used to regulate a rate of magnetic flux by controlling current to the coil so as to control a velocity of the armature upon impact with the stator core.

Claims

1. A method of controlling velocity of an armature of a electronically operated fuel injector as the armature moves from a first position towards a second position, the fuel injector including a stator core at said second position and a coil associated with said stator core, said coil, said stator core and said armature defining a magnetic circuit, said coil generating a magnetic force to cause the armature to move towards and impact said stator core, the method including:

energizing said coil to permit said armature to move towards said stator core;

determining a rate of change of magnetic flux of said magnetic circuit; and

using closed loop feedback control of the determined rate of change of magnetic flux to regulate a rate of magnetic flux by controlling current to said coil so as to control a velocity of said armature upon impact with said stator core.

2. The method according to claim 1, wherein energizing said coil includes permitting current to build until the armature begins to move, feedback of the rate of change of magnetic flux indicating when said armature beings to move, and control of flux is initiated once the armature moves, feedback of the rate of change of magnetic flux determining an end of motion of said armature at which time flux rate control is terminated.

3. The method according to claim 1, wherein the rate of change of magnetic flux is determined by measuring a terminal voltage of said coil.

4. The method according to claim 1, wherein the rate of change of magnetic flux is determined by using a parametrically determined voltage which mirrors a terminal voltage of said coil.

5. The method according to claim 1, wherein the velocity of said armature is controlled so as to be nearly zero as said armature impacts said stator core.

6. A method of controlling movement of an armature of a fuel injector as the armature moves between first and second positions, the fuel injector including a stator core at said second position, a coil associated with said stator core, an injector valve operatively associated with said armature and a spring biasing said injector valve towards a closed position thereof, said injector valve impacting a valve seat when said injector valve is in the closed position thereof and when said armature is generally in the first position thereof, said coil, said stator core and said armature defining a magnetic circuit, said coil generating a magnetic force to cause the armature to move towards and impact said stator core, the method including:

energizing said coil to permit said armature to move towards said stator core;

determining a rate of change of magnetic flux of said magnetic circuit;

using closed loop feedback control of the determined rate of change of magnetic flux to regulate a rate of magnetic flux build-up by controlling current to said coil so as to control a velocity of said armature upon impact with said stator core,

reducing a value of current in said coil to a near zero value to initiate a closing stroke of the injector,

maintaining a biasing current in said coil to permit feedback of the rate of change of magnetic flux,

determining a beginning of armature motion towards said first position thereof by feedback of the rate of change of magnetic flux, and

causing magnetic flux to increase under closed loop control to create a force on said armature opposing a force of said spring biasing said injector valve to control a velocity of said injector valve upon impact with said valve seat.

7. The method according to claim 6, wherein said biasing current is terminated when feedback of the rate of change of magnetic flux has determined that armature motion has ended.

8. The method according to claim 6, wherein the rate of change of magnetic flux is determined by measuring a terminal voltage of said coil.

9. The method according to claim 6, wherein the rate of change of magnetic flux is determined by using a parametrically determined voltage which mirrors a terminal voltage of said coil.

10. The method according to claim 6, wherein the velocity of said armature is controlled so as to be nearly zero as said armature impacts said stator core.

11. A fuel injector comprising:

an armature movable between first and second positions;

an injector valve coupled to said armature for movement between closed and open positions as said armature moves between said first and second positions thereof,

spring structure biasing said injector valve towards the closed position thereof,

a stator core at said second position,

a coil associated with said stator core, said coil, when energized, being constructed and arranged to produce a magnetic force on the armature to cause the armature to move towards the second position and impact said stator core,

circuit structure providing a certain voltage which corresponds to a level of magnetic flux of a magnetic circuit created by said coil, stator core and said armature, and

control structure to control movement of said armature, said control structure being constructed and arranged to determine said certain voltage when said armature is approaching said stator core and to use said certain voltage as a feedback variable to control said level of magnetic flux and thus control a velocity of said armature as said armature impacts said stator core.

12. The fuel injector according to claim 11, wherein said certain voltage corresponds to a rate of change of said magnetic flux.

13. The fuel injector according to claim 11, wherein said control structure is constructed and arranged to measure a terminal voltage of said coil, said terminal voltage defining said certain voltage.

14. The fuel injector according to claim 11, wherein said circuit structure is constructed and arranged to use a parametrically determined voltage which mirrors a terminal voltage of said coil, said control structure determining said parametrically determined voltage, said parametrically determined voltage defining said certain voltage.

15. The fuel injector according to claim 11, wherein said control structure is constructed and arranged to control a velocity of said armature to be near zero upon landing of said armature at said stator core.

16. The fuel injector according to claim 12, wherein said control structure is constructed and arranged to provide a biasing current to said coil to permit feedback of the rate of change of magnetic flux during movement of said injector valve to the closed position thereof so as to control the level of magnetic flux and thus control a velocity of the injector valve as the injector valve moves to the closed position thereof.