Electromagnetic fuel injector

• US 5,012,982 A
• Filed: 06/05/1989
• Issued: 05/07/1991
• Est. Priority Date: 11/15/1986
• Status: Expired due to Term

• Current Assignee: Hitachi Automotive Engineering Company Limited (Hitachi, Ltd.), Hitachi, Ltd.
• Original Assignee: Hitachi Automotive Engineering Company Limited (Hitachi, Ltd.), Hitachi, Ltd.
• Inventors: Ishikawa, Tohru, Kamituma, Yasuo, Kanamaru, Hisanobu, Yokoyama, Mizuho, Souma, Masahiro, Kosuge, Tokuo
• Primary Examiner(s): Kashnikow, Andres
• Assistant Examiner(s): Weldon, Kevin P.
• Application Number:
  US07/361,336
• Time in Patent Office: 701 Days
• Field of Search: 251/129.15, 251/129.21, 239/585, 239/589, 29/156.7 R, 29/156.7 A
• US Class Current: 239/585.4
• CPC Class Codes: F02M 2200/02 Fuel-injection apparatus having means for reducing wear
• CPC Class Codes: F02M 2200/505 Adjusting spring tension by sliding spring seats
• CPC Class Codes: F02M 2200/9038 Coatings
• CPC Class Codes: F02M 51/0682 the body being hollow and its interior communicating with the fuel flow F02M51/0675 takes precedence
• CPC Class Codes: F02M 51/08 specially for low-pressure fuel-injection
• CPC Class Codes: F02M 61/145 the injection nozzle opening into the air intake conduit
• CPC Class Codes: F02M 61/166 Selection of particular materials
• CPC Class Codes: F02M 61/168 Assembling; Disassembling; Manufacturing; Adjusting
• CPC Class Codes: Y10S 239/90 Electromagnetically actuated fuel injector having ball and seat type valve

Abstract

An electromagnetic fuel injector comprising: a movable member with a valve body provided at one end and an armature made of a magnetic material provided at the other end; a cylindrical core made of a magnetic material, the core being disposed in such a manner that the distal end thereof opposes the armature; an electromagnetic coil disposed around the cylindrical core for producing an electromagnetic force between the cylindrical core and the armature when the coil is energized; and guide sections for guiding the movement of the movable member in the axial direction, the guide sections being disposed in the vicinities of the valve body and the armature of the movable member. The guide section provided in the vicinity of the armature comprises a sliding member made of a non-magnetic material and disposed between the armature and the core. The colliding surface of the core and the armature is coated with a nickel layer which serves as an impact absorbing layer and a chromium oxide layer which serves as a surface hardening layer. A seal ring is provided between the outer periphery of a plug portion of the core and the inner periphery of a casing. The yoke is coupled to the core at a location which is closer to a fuel outlet from the seal ring.

Claims

1. An electromagnetic fuel injector comprising a cylindrical yoke opened at its respective ends;

a cylindrical core made of magnetic material connected with one end of said yoke and having a distal end extending into said yoke;

an electromagnetic coil supported between said core and said yoke;

a valve guide fixed in the other end of the yoke and including a guide part for a ball valve located at a position remote from said electromagnetic coil;

an elongated movable member with a ball valve provided at one end and an armature made of a magnetic material provided at the other end thereof;

said elongated moveable member being disposed in such a manner that the distal end of said cylindrical core opposes said armature and said ball valve is disposed adjacent said guide part remote from said electromagnetic coil;

said electromagnetic coil being disposed around said cylindrical core for producing an electromagnetic force between said cylindrical core and said armature when said coil is energized to effect axial movement of said elongated moveable member; and

a guide member for guiding the movement of said elongated movable member in the axial direction and being disposed in the vicinity of said armature of said elongated movable member, said guide member provided in the vicinity of said armature of said elongated movable member being composed of a hollow sliding member made of an on-magnetic material disposed between and engaging with said armature and the distal end of said core so that magnetic flux from said electromagnetic coil does not pass therethrough; and

wherein a sliding surface of the sliding member and an open inner wall surface of the yoke to which the valve guide is fixed are precisely coaxial.

2. An electromagnetic fuel injector according to claim 1, wherein said sliding member made of the non-magnetic material is composed of a cylindrical body, one end of which is fixed to said armature and the other end of which slides along the inner periphery of said cylindrical core.

5. An electromagnetic fuel injector according to claim 1, wherein either of the colliding surfaces of said movable member and said core at which they collide with each other or both of said colliding surfaces are coated with a wear-resistant surface hardening layer, and an impact absorbing layer is interposed between said surface hardening layer and said colliding surface to absorb the impact caused when said movable member and said core collide with each other.

6. An electromagnetic fuel injector according to claim 5, wherein said surface hardening layer is composed of a chromium layer, and said impact absorbing layer is composed of a nickel layer.

7. An electromagnetic fuel injector according to claim 5, wherein said surface hardening layer is composed of a chromium oxide layer, and said impact absorbing layer is composed of a chromium layer.

8. An electromagnetic fuel injector according to claim 5, wherein said surface hardening layer is composed of a layer of nickel with hard particles dispersed therein, and said impact absorbing layer is composed of a nickel layer.

3. An electromagnetic fuel injector, comprising:

a cylindrical yoke opened at its respective ends;

a cylindrical core made of magnetic material connected with one end of said yoke; and

electromagnetic coil supported between said core and said yoke;

a valve guide fixed in the other end of the yoke and including a guide part for a ball valve located at a position remote from said electromagnetic coil;

an elongated movable member with a ball valve provided at one end and an armature made of a magnetic material provided at the other end thereof;

said elongated moveable member being disposed in such a manner that a distal end of said cylindrical core opposes said armature and said ball valve is disposed adjacent said guide part remote from said electromagnetic coil;

said electromagnetic coil being disposed around said cylindrical core for producing an electromagnetic force between said cylindrical core and said armature when said coil is energized to effect axial movement of said elongated moveable member; and

a guide member for guiding the movement of said elongated movable member in the axial direction and being disposed in the vicinity of said armature of said elongated movable member, the guide member in the vicinity of said armature being formed of a hollow retaining member provided between and engaging with the distal end of said core and said armature for maintaining said core and said armature in a coaxial state, said retaining member being formed precisely coaxial with respect to an open inner wall surface of said yoke to which the valve guide is fixed.

4. An electromagnetic fuel injector according to claim 3, wherein said retaining member is composed of a retaining body made of a non-magnetic material, one end of which is fixed to said armature and the other end of which is inserted into said cylindrical core in such a manner that it can slide along the inner periphery of said core.

9. An electromagnetic fuel injector according to claim 3, wherein at least one of the surfaces of said movable member and said core which collide with each other are coated with a wear-resistant surface hardening layer, and an impact absorbing layer is interposed between said surface hardening layer and said colliding surface to absorb the impact caused when said movable member and said core collide with each other.

10. An electromagnetic fuel injector, comprising:

an electromagnetic valve assembly having a yoke having a cylindrical, open ended shape and being made of a magnetic material;

an annular electromagnetic coil retained inside of said yoke;

a core of magnetic material having a plug portion fixed to said guide for sealing one open end of said yoke and a columnar portion inserted into the center of said annular coil within said yoke;

the other open end of said cylindrical yoke opposite said one end having a valve guide secured therein for guiding a ball valve;

said valve guide including fuel outlet means provided at said other end of said yoke at a position remote from said electromagnetic coil;

an elongated movable member having an armature which forms part of a closed magnetic circuit of said electromagnetic coil in cooperation with said yoke and said core at one end thereof, as well as a ball valve for opening and closing a fuel outlet of said fuel outlet means at the other end thereof remote from said one end; and

elastic means for normally urging said elongated movable member in the direction in which said ball valve closes said fuel outlet means;

said electromagnetic valve assembly being accommodated in a casing with sealing means therebetween;

space formed between said casing and said yoke of said electromagnetic valve assembly forming a fuel passageway, said sealing means being interposed between the outer periphery of said plug portion of said core and the inner periphery of said casing,; and

a non-magnetic hollow cylindrical sliding member engaging said armature and said core for guiding the movement of said armature is mounted on one of said armature and said core.

11. An electromagnetic fuel injector according to claim 10, wherein the inner wall of said yoke is caused to press against a protruding portion provided on the outer periphery of said core so as to fix said core to said yoke.

12. An electromagnetic fuel injector according to claim 10, wherein at least one of the surfaces of said movable member and said core which collide with each other are coated with a wear-resistant surface hardening layer, and an impact absorbing layer is interposed between said surface hardening layer and said colliding surface to absorb the impact caused when said movable member and said core collide with each other.

13. An electromagnetic fuel injector, comprising:

a hollow cylindrical yoke having first and second ends;

a cylindrical core connected at said first end of said yoke and having a distal end extending into the hollow interior thereof;

a valve guide fixed in the second end of said yoke and including a guide part for a ball valve;

an elongated moveable member having a ball valve provided at one end and an armature made of a magnetic material provided at the other end thereof, said moveable member being disposed between said core and said valve guide with said armature being adjacent the distal end of said core and said ball valve being within said guide part;

an electromagnetic coil supported between said core and said yoke so as to be disposed around said core adjacent said armature of said moveable member for producing an electromagnetic force between said core and said armature to effect axial movement of said moveable member toward said core;

stop means disposed between said ball valve and said armature for limiting the extent of the axial movement of said moveable member toward said core as produced by said electromagnetic coil; and

a guide member for guiding the movement of said elongated moveable member in the axial direction, the guide member being disposed in the vicinity of said armature for effecting two-position support for said moveable member in cooperation with said guide part of said valve guide, the guide member in the vicinity of said armature being composed of a non-magnetic sliding member in the form of a hollow cylinder disposed between and engaging with said armature and the distal end of said core so that a sliding surface of said sliding member is precisely coaxial with the axis of said core and said moveable member.

14. An electromagnetic fuel injector according to claim 13, wherein said elongated moveable member has an annular projection intermediate said ball valve and said armature, and said stop means includes a fixed stop member having an aperture through which said moveable member extends, said stop member being disposed between said annular projection and said armature.

15. An electromagnetic fuel injector according to claim 13, wherein said elongated moveable member has a projection between said ball valve and said armature, and said stop means includes a fixed stop member aligned with said projection and disposed between said projection and said armature for limiting the extent of movement of said projection toward said core.

16. An electromagnetic fuel injector, comprising:

an elongated moveable member having a ball valve provided at one end and an armature made of magnetic material provided at the other end thereof;

means for supporting said moveable member for axial movement;

a valve seat having a valve part disposed adjacent said ball valve;

means for biasing said moveable member so that said ball valve contacts said valve seat;

electromagnetic coil means disposed adjacent said armature of said moveable member for effecting axial movement of said moveable member to displace said ball valve away from said valve seat;

stop means disposed between said ball valve and said armature for limiting the extent of the axial movement of said moveable member as produced by said electromagnetic coil means; and

guide sections for guiding the movement of said elongated moveable member in the axial direction, the guide sections being disposed in the vicinities of said ball valve and said armature for effecting two-position support for said moveable member, the guide section in the vicinity of said armature being composed of a hollow cylindrical sliding member constructed of a non-magnetic material and engaging with a hollow end portion of said armature.

17. An electromagnetic fuel injector according to claim 16, wherein said elongated moveable member has a projection between said ball valve and said armature, and said stop means includes a fixed stop member aligned with said projection and disposed between said projection and said armature for limiting the extent of movement of said projection toward said core.