US 12,466,388 B2
Method for operating a motor vehicle drive train and electronic control unit for carrying out said method
Roland Neubaur, Vilgertshofen (DE); Florian Hannemann, Gaißach (DE); Markus Pfisterer, Puchheim (DE); and Wolfgang Fickler, Munich (DE)
Assigned to ZF Friedrichshafen AG, Friedrichshafen (DE); and Bayerische Motoren Werke AG (BMW), Munich (DE)
Appl. No. 17/922,035
Filed by ZF Friedrichshafen AG, Friedrichshafen (DE); and Bayerische Motoren Werke AG (BMW), Munich (DE)
PCT Filed Apr. 29, 2021, PCT No. PCT/EP2021/061214
§ 371(c)(1), (2) Date Oct. 28, 2022,
PCT Pub. No. WO2021/219766, PCT Pub. Date Nov. 4, 2021.
Claims priority of application No. 10 2020 205 395.2 (DE), filed on Apr. 29, 2020.
Prior Publication US 2023/0264682 A1, Aug. 24, 2023
Int. Cl. B60W 20/40 (2016.01); B60W 10/02 (2006.01); B60W 10/06 (2006.01); B60W 20/15 (2016.01); F02N 11/08 (2006.01)
CPC B60W 20/40 (2013.01) [B60W 10/02 (2013.01); B60W 10/06 (2013.01); B60W 20/15 (2016.01); F02N 11/0851 (2013.01); B60W 2710/025 (2013.01); B60W 2710/0644 (2013.01)] 14 Claims
OG exemplary drawing
 
1. A method for operating a drive train of a motor vehicle, the drive train comprising an internal combustion engine (VM), an electric machine (EM) having a rotor (R), a transmission (G) for providing different gear speed ratios between an input shaft (GW1) and an output shaft (GW2) of the transmission (G), a starting component (WK, SCI, DC1, DC2) in power flow between the electric machine (EM) and the output shaft (GW2), and a separating clutch (K0) in power flow between the internal combustion engine (VM) and the electric machine (EM), with the rotor (R) of the electric machine (EM) being coupled to the input shaft (GW1), the method comprising:
driving the motor vehicle solely by the electric machine (EM) during a first stage of an electric starting process while the starting component (WK, SCI, DC1, DC2) is engaged or in a slip state, and while the separating clutch (K0) is disengaged;
engaging the separating clutch (K0) during a second stage of the electric starting process to crank the internal combustion engine (VM) using the electric machine (EM), the second stage being subsequent to the first stage;
disengaging the separating clutch (K0) and continuing driving the motor vehicle solely by the electric machine (EM) during a third stage of the electric starting process in which a target drive torque (M_soll) of the motor vehicle increases after the cranking of the internal combustion engine (VM), with an output-side rotational speed (n_EM) of the separating clutch (K0) being lower than an idling speed (n_VM_LL) of the internal combustion engine (VM), the third stage being subsequent to the second stage; and
engaging the separating clutch (K0) during a fourth stage of the electric starting process, after the cranking of the internal combustion engine (VM) and disengaging the separating clutch (K0), to support driving the motor vehicle by the internal combustion engine (VM) only when the target drive torque (M_soll) of the motor vehicle reaches or exceeds a limit value (M_lim), the fourth stage being subsequent to the third stage.