Method for emptying an SCR supply system
AssigneeRobert Bosch GmbH
InventorRohit Joshi
Life of this patent
Estimating the term…
Abstract
Method for emptying an SCR supply system, wherein the SCR supply system comprises a pump with a pump chamber and an actively controllable inlet valve and an actively controllable outlet valve, wherein an emptying process of the SCR supply system is detected and controlled as a function of the pressure curve in negative pressure phases and/or criteria determined in pressure release phases.
Claims7
A method for emptying an SCR supply system (100) having a pump (210) with a pump chamber (220), an actively controllable inlet valve (221), and an actively controllable outlet valve (222), wherein the SCR supply system (100) is connected to a fluid tank (120) via the inlet valve (221) and a line (124), and the SCR supply system (100) is connected to the pressure line (122) and a dosing valve (130) via the outlet valve (222), the method comprising:
- determining a pressure (p) in the pressure line (122) using a pressure sensor (123);
- controlling the SCR supply system (100) in an operating state with a stable minimum pressure;
- closing the dosing valve (130);
- emptying the SCR supply system (100) by performing a negative pressure process (Ci)
- that includes alternately performing a negative pressure phase and a pressure release phase,
- wherein the negative pressure phase includes
- determining first negative pressure times (t1up,Ci) for which the pressure (p) in the pressure line (122) reaches a specifiable first negative pressure (pup1) and second negative pressure times (t2up,Ci) for which the pressure (p) in the pressure line (122) reaches a specifiable second negative pressure (pup2),
- waiting for a specifiable waiting time (twait) after the specifiable second negative pressure (pup2) has been reached,
- wherein the pressure release phase is performed after the specifiable second negative pressure (pup2) or the specifiable waiting time (twait) has been reached,
- wherein performing the pressure release phase includes
- opening the dosing valve (130), and
- in response to the pressure (p) in the pressure line (122) reaching the specifiable first negative pressure (p), closing the dosing valve (130);
- and
- the method further includes
- determining negative pressure time differences (Δtup,Ci) between the second negative pressure times (t2up,Ci) and the first negative pressure times (t2up,Ci), and
- in response to one of the negative pressure time differences (Δtup,Ci) exceeding a specifiable first reference time difference (Δtup,Ref), terminating the emptying process of the SCR supply system (100).
A non-transitory, computer readable medium storing instructions that when executed by a computer cause the computer to perform a set of operations for controlling an SCR supply system (100) having a pump (210) with a pump chamber (220), an actively controllable inlet valve (221), and an actively controllable outlet valve (222), wherein the SCR supply system (100) is connected to a fluid tank (120) via the inlet valve (221) and a line (124), and wherein the SCR supply system (100) is connected to the pressure line (122) and a dosing valve (130) via the outlet valve (222), the set of operations comprising:
- determining a pressure (p) in the pressure line (122) using a pressure sensor (123);
- controlling the SCR supply system (100) in an operating state with a stable minimum pressure;
- closing the dosing valve (130);
- emptying of the SCR supply system (100) by performing a negative pressure process (Ci)
- that includes alternately performing a negative pressure phase and a pressure release phase,
- wherein the negative pressure phase includes
- determining first negative pressure times (t1up,Ci) for which the pressure (p) in the pressure line (122) reaches a specifiable first negative pressure (pup1) and second negative pressure times (t2up,Ci) for which the pressure (p) in the pressure line (122) reaches a specifiable second negative pressure (pup2),
- waiting for a specifiable waiting time (twait) after the specifiable second negative pressure (pup2) has been reached,
- wherein the pressure release phase is performed after the specifiable second negative pressure (pup2) or the specifiable waiting time (twait) has been reached,
- wherein performing the pressure release phase includes
- opening the dosing valve (130), and
- in response to the pressure (p) in the pressure line (122) reaching the specifiable first negative pressure (p), closing the dosing valve (130);
- and
- the method further includes
- determining negative pressure time differences (Δtup,Ci) between the second negative pressure times (t2up,Ci) and the first negative pressure times (t2up,Ci), and
- in response to one of the negative pressure time differences (Δtup,Ci) exceeding a specifiable first reference time difference (Δtup,Ref), terminating the emptying process of the SCR supply system (100).
A device for emptying an SCR supply system (100) having a pump (210) with a pump chamber (220), an actively controllable inlet valve (221), and an actively controllable outlet valve (222), wherein the SCR supply system (100) is connected to a fluid tank (120) via the inlet valve (221) and a line (124), and the SCR supply system (100) is connected to the pressure line (122) and a dosing valve (130) via the outlet valve (222), the device comprising an electronic processor configured to perform a set of operations comprising:
- determining a pressure (p) in the pressure line (122) using a pressure sensor (123);
- controlling the SCR supply system (100) in an operating state with a stable minimum pressure;
- closing the dosing valve (130);
- emptying the SCR supply system (100) by performing a negative pressure process (Ci) that includes alternately performing a negative pressure phase and a pressure release phase,
- wherein the negative pressure phase includes
- determining first negative pressure times (t1up,Ci) for which the pressure (p) in the pressure line (122) reaches a specifiable first negative pressure (pup1) and second negative pressure times (t2up,Ci) for which the pressure (p) in the pressure line (122) reaches a specifiable second negative pressure (pup2),
- waiting for a specifiable waiting time (twait) after the specifiable second negative pressure (pup2) has been reached,
- wherein the pressure release phase is performed after the specifiable second negative pressure (pup2) or the specifiable waiting time (twait) has been reached,
- wherein performing the pressure release phase includes
- opening the dosing valve (130), and
- in response to the pressure (p) in the pressure line (122) reaching the specifiable first negative pressure (p), closing the dosing valve (130);
- and
- the method further includes
- determining negative pressure time differences (Δtup,Ci) between the second negative pressure times (t2up,Ci) and the first negative pressure times (t2up,Ci), and
- in response to one of the negative pressure time differences (Δtup,Ci) exceeding a specifiable first reference time difference (Δtup,Ref), terminating the emptying process of the SCR supply system (100).
Dependencies are inferred from the claim text.