Device for generating a reducing agent/air mixture

• US 20040115074A1
• Filed: 02/11/2004
• Published: 06/17/2004
• Est. Priority Date: 09/29/2000
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Huber, Sven, Mayer, Hanspeter
• Granted Patent: US 7,431,573 B2
• Time in Patent Office: Days
• US Class Current: 417/413.1
• CPC Class Codes: B01F 23/23 by introducing gases into liquid media, e.g. for producing aerated liquids
• CPC Class Codes: B01F 25/105 Mixing heads, i.e. compact mixing units or modules, using mixing valves for feeding and mixing at least two components
• CPC Class Codes: B01F 25/314 wherein additional components are introduced at the circumference of the conduit
• CPC Class Codes: B01F 35/71 Feed mechanisms with proportioning B01F35/80
• CPC Class Codes: B01F 35/712 for feeding fluids
• CPC Class Codes: B01F 35/7174 using pistons, plungers or syringes
• CPC Class Codes: B01F 35/71761 Membrane pumps
• CPC Class Codes: B01F 35/71805 using valves, gates, orifices or openings
• 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 3/2066 Selective catalytic reduction [SCR]
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies
• CPC Class Codes: Y10T 137/7889 Sleeve

Abstract

The apparatus (10) for generating a mixture of reducing agent and air has a feed pump (16), by which reducing agent is pumped and which has a pump housing (22, 32). The apparatus (10) furthermore has a mixing chamber (50), into which reducing agent and air pumped by the feed pump (16) can be introduced; the mixing chamber (50) is embodied in a mixing chamber body (36). The mixing chamber body (36) communicates directly with the pump housing (22, 32) of the feed pump (16) and forms a cap of the pump housing (22, 32). The feed pump (16) has a drive shaft (24) for a feed element (30), which protrudes into the pump housing (22) of the feed pump (16), and the mixing chamber body (36) is disposed at least approximately radially to the drive shaft (24). The apparatus (10) has a compact structural size and only a slight reducing agent-filled idle volume.

Claims

1. An apparatus for generating a mixture of reducing agent and air, having a feed pump (16) by which reducing agent is pumped and which has a pump housing (22, 32), and having a mixing chamber (50), in which reducing agent and air pumped by the feed pump (16) can be introduced, the mixing chamber (50) being embodied in a mixing chamber body (36), characterized in that the mixing chamber body (36) communicates with the pump housing (22, 32) of the feed pump (16).

2. The apparatus of claim 1, characterized in that the mixing chamber body (36) forms a cap of the pump housing (22, 32).

3. The apparatus of claim 1 or 2, characterized in that the feed pump (16) has a drive shaft (24) for a feed element (30), which protrudes into the pump housing (22) of the feed pump (16);

and that the mixing chamber body (36) is disposed at least approximately radially to the drive shaft (24).

4. The apparatus of one of claims 1-3, characterized in that a reducing-agent supply stub (38) is disposed on the mixing chamber body (36);

and that between the reducing-agent supply stub and a work chamber (34) of the feed pump (16), a check valve (40) opening into the work chamber (34) is disposed.

5. The apparatus of one of claims 1-4, characterized in that a further check valve (60), opening into the mixing chamber (50), is disposed between an outlet (46) of the feed pump (16) and the mixing chamber (50).

6. The apparatus of one of the foregoing claims, characterized in that the mixing chamber (50) is embodied in a bore (52) of the mixing chamber body (36);

that an elastically compressible sleeve (54) is pressed into the bore (52); and

that an air inlet (56) discharges into the bore (52) at the circumference of the sleeve (54), and the sleeve (54) is elastically compressible by the air, supplied under pressure, so that air can reach the mixing chamber (50) through an annular gap (55) forming between the bore (52) and the sleeve (54).

7. The apparatus of claim 5 and 6, characterized in that the further check valve (60) is embodied integrally with the sleeve (54), in the form of lips (62) protruding inward from the sleeve that rest sealingly on one another and that can be moved away from one another, for opening a passage, under the influence of the feed pressure generated by the feed pump (16).

8. The apparatus of one of the foregoing claims, characterized in that a stub (42) leading away from the mixing chamber (50) is formed integrally onto the mixing chamber body (36), and the generated mixture of reducing agent and air emerges through this stub.

9. The apparatus of one of the foregoing claims, characterized in that the feed pump (16) has an electric drive motor (20) embodied as a stepping motor.