Plasma injector, exhaust gas purifying system and method for injecting reducing agent

• US 7,481,043 B2
• Filed: 12/15/2004
• Issued: 01/27/2009
• Est. Priority Date: 12/18/2003
• Status: Expired due to Fees

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Hirata, Hirohito, Matsumura, Eriko
• Primary Examiner(s): Tran; Binh Q.
• Application Number:
  US10/583,311
• Publication Number:
  US 20070261397A1
• Time in Patent Office: 1,504 Days
• Field of Search: 602/74, 602/75, 602/86, 602/95, 602/97, 603/03, 422/186.04, 422/186.15, 422/186.16, 422/186.21, 422/186.22, 239/132, 239/133, 239/134, 239/135
• US Class Current: 60/286
• CPC Class Codes: B01D 2259/818 Employing electrical discharges or the generation of a plasma
• CPC Class Codes: B01D 53/90 Injecting reactants
• CPC Class Codes: B01D 53/925 Simultaneous elimination of carbon monoxide or hydrocarbons and nitrogen oxides
• CPC Class Codes: F01N 2240/28 a plasma reactor
• CPC Class Codes: F01N 2570/14 Nitrogen oxides
• CPC Class Codes: F01N 2610/03 the substance being hydrocarbons, e.g. engine fuel
• CPC Class Codes: F01N 2610/1453 Sprayers or atomisers; Arrangement thereof in the exhaust apparatus
• CPC Class Codes: F01N 3/2066 Selective catalytic reduction [SCR]
• CPC Class Codes: F01N 3/36 Arrangements for supply of additional fuel
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies

Abstract

The present invention provides a plasma injector wherein a reducing agent injected from an injection port (19) at the distal end portion of an injection nozzle (18) is at least partially converted into a plasma; an exhaust gas purifying system; and a method for injecting a reducing agent. Using the plasma injector, the exhaust gas purifying system, and the method for injecting a reducing gas of the present invention, it is possible to vaporize a reducing agent supplied in an injection manner and/or to provide a highly reactive reducing agent from the reducing agent.

Claims

1. A plasma injector for injecting a reducing agent,

wherein said plasma injector comprises a injection nozzle and a plasma generator which generates a plasma in the vicinity of a injection port at the distal end portion of said injection nozzle;

wherein said plasma injector injects a reducing agent in a liquid droplet state, and at least partially converts the reducing agent injected in a liquid droplet state into a plasma to vaporize the reducing agent; and

wherein said plasma generator is located on the distal end portion of said injecting nozzle.

2. The plasma injector according to claim 1, wherein said plasma is an inductive-coupling plasma;

wherein said plasma generator located at the distal end portion of said injection nozzle comprises a cup-shaped member surrounding the injection port of said injection nozzle, and an inductive-coil surrounding around said cup-shaped member; and

wherein said cup-shaped member is made of an electromagnetic wave-transmissive material.

3. The plasma injector according to claim 1, wherein the plasma is an electric-discharge plasma;

wherein said plasma generator located at the distal end portion of the injection nozzle comprises a cup-shaped member surrounding the injection port of said injection nozzle;

wherein said cup-shaped member is made of an electrically semiconductive material or an electrically conductive material; and

wherein said cup-shaped member and said distal end portion of the nozzle are electrically insulated from each other to form an electrode couple together.

4. The plasma injector according to claim 1, wherein the plasma is an electric-discharge plasma, a microwave plasma or an inductive-coupling plasma.

5. An exhaust gas purifying system, wherein a reducing agent is injected upstream of a catalyst located in an exhaust pipe;

and wherein said reducing agent is injected by said plasma injector according to claim 1.

6. The exhaust gas purifying system according to claim 5, wherein said catalyst is a NO_x purifying catalyst.

7. An exhaust gas purifying system, wherein a reducing agent is injected upstream of a catalyst located in an exhaust pipe;

and wherein said reducing agent is injected by said plasma injector according to claim 2.

8. An exhaust gas purifying system, wherein a reducing agent is injected upstream of a catalyst located in an exhaust pipe;

and wherein said reducing agent is injected by said plasma injector according to claim 3.

9. An exhaust gas purifying system, wherein a reducing agent is injected upstream of a catalyst located in an exhaust pipe;

and wherein said reducing agent is injected by said plasma injector according to claim 4.

10. The exhaust gas purifying system according to claim 7, wherein said catalyst is a NO_x purifying catalyst.

11. The exhaust gas purifying system according to claim 8, wherein said catalyst is a NO_x purifying catalyst.

12. The exhaust gas purifying system according to claim 9, wherein said catalyst is a NO_x purifying catalyst.

13. The plasma injector according to claim 1, wherein the plasma is in a region within 5 cm from the injection port.

14. The exhaust gas purifying system according to claim 5, wherein plasma is generated only at the moment of injecting the reducing agent under a condition that the system is not sufficiently warmed up.