# US 9,752,483 B2 · Method of operating a dosing device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,752,483 B2 - Document ID: US9752483B2 - Status: Granted - Kind: B2 - Application number: 15/075,739 - Filed: 2016-03-21 - Published: 2016-07-14 - Granted: 2017-09-05 - Earliest claimed: 2012-03-15 - Assignees: Robert Bosch GmbH - Applicants: Robert Bosch GmbH - Inventors: Matthias Burger - Web page: https://patentgrep.com/patent/US9752483B2 ## CPC - F01N 3/208: {Control of selective catalytic reduction [SCR], e.g. by adjusting the dosing of reducing agent} - F01N 3/0253: {adding fuel to exhaust gases} - F01N 3/08: for rendering innocuous (using electric or electrostatic separators F01N3/01; chemical aspects B01D53/92) - F01N 3/2066: {Selective catalytic reduction [SCR]} - F01N 3/36: Arrangements for supply of additional fuel - F01N 9/002: {of filter regeneration} - F01N 2610/14: Arrangements for the supply of substances, e.g. conduits - F01N 2610/1433: Pumps - F01N 2610/1453: Sprayers or atomisers; Arrangement thereof in the exhaust apparatus - F01N 2900/16: said parameters being related to the exhaust apparatus, e.g. particulate filter or catalyst - Y02A 50/20: Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters - Y02T 10/12: Improving ICE efficiencies - Y10T 137/85978: With pump - F01N: GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES (arrangements in connection with gas exhaust of propulsion units in vehicles B60K13/00; combustion-air intake silencers specially adapted for, or arranged on, internal-combustion engines F02M35/00; protecting against, or damping, noise in general G10K11/16) - Y02A: TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A method of operating a dosing device. A dosing valve is provided with low-pressure and high-pressure chambers delimited by a piston whose travel is limited to a predefined maximum stroke. A pump operates to deliver the liquid at pre-delivery pressure. The dosing valve actuates under direction of a control unit by opening a 2/2 directional valve to direct the pumped liquid into the low-pressure chamber, and in response, the piston initiates a stroke. The liquid is injected from the high-pressure chamber into the exhaust-gas stream during the stroke of the piston, and the injection stops when the piston reaches maximum stroke. The control unit holds the directional valve open for longer than the piston requires to perform its maximum stroke so that the dosing valve delivers a predetermined volumetric dose of the liquid into the exhaust-gas stream, the predetermined volumetric dose corresponding directly to the maximum stroke of the piston. ## Claims ### Claim 1 A method of operating a dosing device (15) for introducing a liquid medium into an exhaust-gas stream of an internal combustion engine (1) of a motor vehicle, the method comprising: providing a dosing valve (13) with at least one low-pressure chamber (47) and at least one high-pressure chamber (41), wherein the low-pressure chamber (47) and the high-pressure chamber (41) are delimited by a piston (49) and a part of the piston which delimits the low-pressure chamber has a larger diameter than a part of the piston which delimits the high-pressure chamber, and the piston (49) travel is limited to a predefined maximum stroke; operating a pump (23) to deliver the liquid medium at a pre-delivery pressure into a delivery line (19); actuating the dosing valve (13) under direction of a control unit (31) by opening a 2/2 directional valve (17) along the delivery line (19) to direct the pumped liquid medium at the pre-delivery pressure into the low-pressure chamber (47) of the dosing valve (13), and in response, the piston (49) initiating a stroke; and injecting the liquid medium from the high-pressure chamber (41) into the exhaust-gas stream during the stroke of the piston (49), the injection stopping when the piston (49) reaches the maximum stroke, wherein the control unit (31) holds the 2/2 directional valve (17) open for longer than the piston (49) requires to perform its maximum stroke so that the dosing valve (13) delivers a predetermined volumetric dose of the liquid medium into the exhaust-gas stream, the predetermined volumetric dose corresponding directly to the maximum stroke of the piston (49). ### Claim 2 (depends on 1) The method of claim 1, wherein the injection is carried out until the piston (49) contacts a lower stroke stop (52) on a cylinder (45) within a housing (33). ### Claim 3 (depends on 2) The method of claim 2, further comprising returning the piston (49) along a return stroke until the piston (49) contacts a spacer device (53) positioned within the housing (33) to set the maximum stroke. ### Claim 4 (depends on 1) The method of claim 1, wherein, during the injection as the piston (49) strokes, the piston (49) compresses a check valve (55, 57) that is held in a closed position through the stroke of the piston (49). ### Claim 5 (depends on 1) The method of claim 1, further comprising opening a check valve (55, 57) when pressure in the low-pressure chamber (47) is higher than pressure in the high-pressure chamber (41) after the piston (49) is stroked to the maximum stroke, and re-closing the check valve (55, 57) when the pressure in the low-pressure chamber (47) is lower than the pressure in the high-pressure chamber (41). ### Claim 6 (depends on 1) The method of claim 1, wherein the liquid medium injected by the dosing device (15) is a liquid reducing agent for nitrogen oxide reduction. ### Claim 7 (depends on 1) The method of claim 1, wherein the liquid medium injected by the dosing device (15) is diesel fuel for particle filter regeneration. ### Claim 8 (depends on 1) The method of claim 1, further comprising placing a spacer device (53) into position within the housing (33) to set the maximum stroke of the piston (49). ### Claim 9 A method of operating a dosing device (15) for introducing a liquid medium into an exhaust-gas stream of an internal combustion engine (1) of a motor vehicle, the method comprising: providing a dosing valve (13) with at least one low-pressure chamber (47) and at least one high-pressure chamber (41) within a housing (33), wherein the low-pressure chamber (47) and the high-pressure chamber (41) are delimited by a piston (49) and a part of the piston which delimits the low-pressure chamber has a larger diameter than a part of the piston which delimits the high-pressure chamber; setting a travel limit of the piston (49) to a predefined maximum stroke by selection of a spacer device (53) and insertion of the spacer device (53) into the housing (33); operating a pump (23) to deliver the liquid medium at a pre-delivery pressure into a delivery line (19); opening a 2/2 directional valve (17) along the delivery line (19) to direct the pumped liquid medium at the pre-delivery pressure into the low-pressure chamber (47) of the dosing valve (13), and in response, the piston (49) initiating a stroke; injecting the liquid medium from the high-pressure chamber (41) into the exhaust-gas stream only during the stroke of the piston (49) until the piston (49) contacts a lower stroke stop (52) within the housing (33); and maintaining the 2/2 directional valve (17) open until after the piston (49) contacts the lower stroke stop (52) so that the dosing valve (13) injects a predetermined volumetric dose of the liquid medium corresponding directly to the maximum stroke of the piston (49). ### Claim 10 (depends on 9) The method of claim 9, further comprising returning the piston (49) along a return stroke until the piston (49) contacts the spacer device (53). ### Claim 11 (depends on 9) The method of claim 9, wherein, during the injection as the piston (49) strokes, the piston (49) compresses a check valve (55, 57) that is held in a closed position through the stroke of the piston (49). ### Claim 12 (depends on 9) The method of claim 9, further comprising opening a check valve (55, 57) when pressure in the low-pressure chamber (47) is higher than pressure in the high-pressure chamber (41) after the piston (49) is stroked to the maximum stroke, and re-closing the check valve (55, 57) when the pressure in the low-pressure chamber (47) is lower than the pressure in the high-pressure chamber (41). ### Claim 13 (depends on 9) The method of claim 9, wherein the liquid medium injected by the dosing device (15) is a liquid reducing agent for nitrogen oxide reduction. ### Claim 14 (depends on 9) The method of claim 9, wherein the liquid medium injected by the dosing device (15) is diesel fuel for particle filter regeneration. ### Claim 15 (depends on 9) The method of claim 9, wherein the 2/2 directional valve (17) is opened as directed by a control unit (31) that does not manipulate the piston stroke of the dosing valve (13).