Device for introducing a liquid reducing agent into an exhaust gas purification system

• US 6,273,120 B1
• Filed: 05/12/2000
• Issued: 08/14/2001
• Est. Priority Date: 11/12/1998
• Status: Expired due to Term

• Current Assignee: Johnson Matthey Catalysts (Germany) Gmbh (Johnson Matthey PLC)
• Original Assignee: Siemens AG
• Inventors: Hofmann, Lothar, Mathes, Wieland
• Primary Examiner(s): Hepperle, Stephen M.
• Application Number:
  US09/569,285
• Time in Patent Office: 459 Days
• Field of Search: 602/86, 137/114, 137/98
• US Class Current: 137/98
• CPC Class Codes: B01D 53/8631 Processes characterised by a specific device
• CPC Class Codes: B01D 53/8696 Controlling the catalytic process
• CPC Class Codes: B01D 53/9431 Processes characterised by a specific device
• CPC Class Codes: B01D 53/9495 Controlling the catalytic process
• CPC Class Codes: F01N 2610/02 the substance being ammonia or urea
• CPC Class Codes: F01N 2610/08 with prior mixing of the substances with a gas, e.g. air
• CPC Class Codes: F01N 2610/1473 Overflow or return means for the substances, e.g. conduits or valves for the return path
• CPC Class Codes: F01N 3/2066 Selective catalytic reduction [SCR]
• CPC Class Codes: Y02C 20/10 of nitrous oxide (N2O)
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies
• CPC Class Codes: Y10T 137/2514 Self-proportioning flow systems

Abstract

A device for introducing a liquid reducing agent into an exhaust gas purification system includes a gas line for receiving and carrying a gas, a reducing agent line for receiving and carrying a liquid reducing agent, a mixing chamber for mixing the reducing agent with the gas, the mixing chamber fluidically connected to the gas line and to the aid reducing agent line, a metering valve disposed in the reducing agent line; and a control device for controlling a pressure in the reducing agent line dependent upon a gas pressure in the gas line. The control device can also be used for controlling the reducing agent throughput in the reducing agent line in dependence on the gas pressure in the gas line.

Claims

1. A device for introducing a liquid reducing agent into an exhaust gas purification system, comprising:

a gas line for receiving and carrying a gas;

a reducing agent line for receiving and carrying a liquid reducing agent;

a mixing chamber fluidically connected to said gas line and to said reducing agent line for mixing the reducing agent with the gas;

a metering valve disposed in said reducing agent line, across which a pressure difference is created; and

a control device controlling a reducing agent pressure in said reducing agent line dependent upon a gas pressure in said gas line to keep the pressure difference constant.

2. The device according to claim 1, wherein said control device includes an actuating member for controlling the pressure in said reducing agent line.

3. The device according to claim 2, wherein said actuating member is a pressure control valve controlled by the gas pressure in said gas line.

4. The device according to claim 3, wherein said metering valve precedes said mixing chamber with respect to a flow direction of the reducing agent and has an inlet, and said pressure control valve is disposed at said inlet of said metering valve.

5. The device according to claim 3, including a branch line, said pressure control valve fluidically connecting said branch line to said reducing agent line.

6. The device according to claim 4, including a branch line, said pressure control valve fluidically connecting said branch line to said reducing agent line.

7. The device according to claim 5, wherein said branch line is connected to said reducing agent line upstream of said metering valve with respect to a flow direction of the reducing agent.

8. The device according to claim 6, wherein said branch line is connected to said reducing agent line upstream of said metering valve with respect to a flow direction of the reducing agent.

9. The device according to claim 1, including a reservoir for holding the reducing agent, said reducing agent line being fluidically connected to said reservoir.

10. The device according to claim 5, including a reservoir for holding the reducing agent, said branch line being fluidically connected to said reservoir.

11. The device according to claim 6, including a reservoir for holding the reducing agent, said branch line being fluidically connected to said reservoir.

12. The device according to claim 5, wherein said pressure control valve is a three-way valve disposed in said reducing agent line, and said three-way valve is fluidically connected to said branch line.

13. The device according to claim 6, wherein said pressure control valve is a three-way valve disposed in said reducing agent line, and said three-way valve is fluidically connected to said branch line.

14. The device according to claim 5, wherein said pressure control valve is a two-way valve disposed in said branch line.

15. The device according to claim 6, wherein said pressure control valve is a two-way valve disposed in said branch line.

16. The device according to claim 1, including a pressure extraction line fluidically connecting said control device to said gas line.

17. The device according to claim 2, including a pressure extraction line fluidically connecting said control device to said gas line, and said actuating member is a pneumatically controlled pressure control valve.