Method for operating a hybrid electric vehicle, computer program product and control unit, and hybrid electric vehicle with such a control unit

Abstract

The invention relates to a method for operating a hybrid electric vehicle (2), at least comprising the following steps: (S1400) Reading a battery state value (BSV) indicative of the state of a traction battery (28) of the hybrid electric vehicle (2) and comparing the battery state value (BSV) with a battery state reference value (BSR), and (S1500) Activating an eEGH (20) of the hybrid electric vehicle (2) when the battery state of charge (BZW) is greater than the battery state of charge reference (BZR), and / or (S28 00) Reading a temperature value (TW) indicative of an ambient temperature of the hybrid electric vehicle (2) and comparing the temperature value (TW) with a temperature reference value (TR), and (S1700) Starting an internal combustion engine (6) of the hybrid electric vehicle (2) with a starter generator (14) of the hybrid electric vehicle (2) when the temperature value (TW) is greater than the temperature reference value (TR), and / or (S2900) Starting an internal combustion engine (6) of the hybrid electric vehicle (2) with a starter (16) of the hybrid electric vehicle (2) when the temperature value (TW) is less than the temperature reference value (TR).

Description

[0001] The invention relates to a method for operating a hybrid electric vehicle, a computer program product and a control unit, as well as a hybrid electric vehicle with such a control unit.

[0002] A hybrid electric vehicle (HEV) is an electric vehicle powered by at least one electric motor and an additional energy converter, drawing energy from both its electrical storage (traction battery) and an onboard fuel. This additional energy converter is an internal combustion engine, typically a gasoline or diesel engine.

[0003] Such a hybrid drive can reduce the exhaust emissions of the internal combustion engine.

[0004] There is a need to identify ways in which the exhaust emissions of such a hybrid electric vehicle can be further reduced.

[0005] The object of the invention is solved by a method for operating a hybrid electric vehicle, at least with the following steps: Reading a battery state value indicative of the condition of a traction battery of the hybrid electric vehicle and comparing the battery state value with a battery state reference value, and activating an eEGH of the hybrid electric vehicle if the battery state value is greater than the battery state reference value, and / or Reading a temperature value indicative of the ambient temperature of the hybrid electric vehicle and comparing the temperature value with a temperature reference value, and Starting an internal combustion engine of the hybrid electric vehicle with a starter generator of the hybrid electric vehicle when the temperature value is greater than the temperature reference value, and / or Starting the combustion engine of the hybrid electric vehicle with a starter motor of the hybrid electric vehicle when the temperature value is less than the temperature reference value.

[0006] The two step combinations – reading a battery status value and activating an eEGH of the hybrid electric vehicle, and reading a temperature value and starting an internal combustion engine of the hybrid electric vehicle with a starter generator or with a starter motor of the hybrid electric vehicle – can be executed in any order.

[0007] An eEGH is understood to be an electric exhaust gas heater (also E-Kat) which has at least one electric heating element for heating the exhaust gas flow of the internal combustion engine or at least one catalyst of an exhaust aftertreatment system of the hybrid electric vehicle.

[0008] In other words, preheating with the eEGH occurs if the battery condition allows it. If the battery condition does not allow it, a warm start or a cold start is performed, depending on the ambient temperature.

[0009] By using an eEGH powered by the traction battery, exhaust emissions can be reduced, especially during the start-up process of such a hybrid electric vehicle, because the use of the eEGH allows at least one catalyst of the exhaust aftertreatment system of the electric hybrid vehicle to reach its minimum operating temperature more quickly.

[0010] According to one embodiment, the method further comprises the following steps: Reading in a shutdown time to record a cooling period, and Performing a warm start of the combustion engine of the hybrid electric vehicle when the cooling time is longer than a reference time.

[0011] In other words, if the combustion engine and the exhaust aftertreatment system have not yet cooled down, a warm start is performed. Therefore, the eEGH (electro-ignition starter) is not needed in this case. This protects the traction battery and allows for a lower CO2 starting process.

[0012] According to another embodiment, the battery state of charge value is based on the detection and evaluation of a state of charge and / or an aging state and / or a battery cell temperature and / or a health status of the traction battery. For example, a battery management system (BMS) can determine and evaluate these values. The battery management system can weight these values ​​and combine them into a single value, which is then compared with a predetermined threshold. If the threshold is exceeded, the traction battery has a battery state that allows preheating with the eEGH. In this way, the battery state of charge can be determined with particular accuracy.

[0013] According to another embodiment, when the combustion engine of the hybrid electric vehicle is started using the starter motor of the hybrid electric vehicle, a cold start is performed. This protects the traction battery of the hybrid electric vehicle at cold ambient temperatures.

[0014] Furthermore, the invention includes a computer program product and a control unit, as well as a hybrid electric vehicle with such a control unit.

[0015] The invention will now be explained with the aid of a drawing. The drawing shows: Fig. 1. Schematic representation of components of a powertrain of a hybrid electric vehicle. Fig. 2 in schematic representation further details of the in Fig. 1 of the control unit shown. Fig. 3. A schematic representation of the procedure for operating the in Fig. 1 hybrid electric vehicle shown. Fig. 4. A schematic representation of an activity flow diagram for the operation of the [system / device] in the Fig. 1 hybrid electric vehicle shown.

[0016] It will initially be on Fig. 1 referenced.

[0017] Shown are components of a powertrain 4 of a hybrid electric vehicle 2.

[0018] In the present embodiment, the hybrid electric vehicle 2 is designed as a passenger car. In contrast to the present embodiment, the hybrid vehicle 2 can also be designed as another type of land vehicle, such as a commercial vehicle, truck, or bus.

[0019] Furthermore, the hybrid electric vehicle 2 in the present embodiment can be designed as a full hybrid (FHEV), as a plug-in hybrid (PHEV) or mild hybrid.

[0020] Furthermore, in the present embodiment, the hybrid electric vehicle 2 can be designed as a parallel hybrid or as a mixed hybrid.

[0021] In the present embodiment, the hybrid electric vehicle 2 is a parallel hybrid and a mild hybrid of category P0.

[0022] The powertrain 4 of the hybrid electric vehicle 2 includes all components that generate the power for propulsion in the hybrid electric vehicle 2 and transfer it to a roadway.

[0023] In the present embodiment, the components of the drive train 4 include an internal combustion engine 6, which is connected to a gearbox 10 via a clutch 8 for torque transmission. Two drive wheels 12a, 12b of the hybrid electric vehicle 2 are in turn connected to the gearbox 10 for torque transmission.

[0024] In the present embodiment, the internal combustion engine 6 is a gasoline engine. In contrast to the present embodiment, it could also be a diesel engine.

[0025] Furthermore, in the present embodiment, a starter generator 14 is assigned to the drive train 4; in this embodiment, a belt-driven integrated starter generator (BiSG) is assigned. Alternatively, the drive train 4 can also include a crankshaft-mounted integrated starter generator (C-ISG).

[0026] When the starter generator 14 is operated as a motor, e.g., to start or assist the internal combustion engine 6, it is supplied with operating energy from a traction battery 28, in this embodiment a 48V battery. When, on the other hand, the starter generator 14 is operated as a generator, it feeds, e.g., recuperation energy gained during braking, into the traction battery 28 and, in this embodiment, additionally via a DC / DC converter 34a into an on-board battery 30, in this embodiment a 12V on-board battery, and into the on-board electrical system 32, in this embodiment a 12V on-board electrical system, of the hybrid electric vehicle 2.

[0027] In addition to the starter generator 14, a starter motor 16 is also connected to the internal combustion engine 6 in a torque-transmitting manner in the present embodiment, so that the internal combustion engine 6 can also be started using the starter motor 16. The starter motor 16 is supplied with operating energy from the vehicle battery 30 via the vehicle electrical system 32.

[0028] Furthermore, in the present embodiment, an exhaust aftertreatment device 18 is provided for the exhaust aftertreatment of exhaust gases from the internal combustion engine 6. For this purpose, the exhaust aftertreatment device 16 in the present embodiment has a catalyst 24, such as a diesel oxidation catalyst (diesel oxidation catalytic converter - DOC).

[0029] An eEGH 20 is connected upstream of the catalyst 24 in the exhaust gas flow direction. The eEGH 20 is an electric exhaust gas heater (also E-Kat) which has at least one electric heating element for heating the exhaust gas flow of the internal combustion engine 6 or the catalyst 24.

[0030] The eEGH 20 is supplied with operating energy via a DC / DC converter 34b from the traction battery 28 or from the generator-operated starter generator 14.

[0031] Temperature sensors 22a, 22b are provided upstream and downstream of the eEGH 20 to record the temperature of the exhaust gas flow before and after the eEGH 20.

[0032] The temperature sensors 22a, 22b are connected to a control unit 26 for the transmission of measurement data, which is connected to the aforementioned components for the transmission of control signals ST.

[0033] The control unit 26 and the aforementioned components may each include hardware and / or software components for the tasks and functions described below.

[0034] It will now also be applied to Fig. 2 Reference is made to explain further details of control unit 26.

[0035] The control unit 26 is designed to read a battery status value BZW, which is indicative of the condition of the traction battery 28, and to compare the battery status value BZW with a battery status reference value BZR.

[0036] The battery state of charge (BZW) is determined by a battery management system 36. In the present embodiment, the battery management system 36 detects and evaluates the state of charge, the state of aging, the battery cell temperature, and the health status of the traction battery 28. In contrast to the present embodiment, it is also possible, for example, to detect only the state of charge and compare it with a state of charge reference value of, for example, 75%.

[0037] Furthermore, the control unit 26 is designed to activate the eEGH 20 by means of a corresponding control signal ST when the battery status value BZW is greater than the battery status reference value BZR.

[0038] Furthermore, the control unit 26 is configured to read a temperature value TW indicative of the ambient temperature of the hybrid electric vehicle 2 and to compare the temperature value TW with a temperature reference value TR. If the temperature value TW is greater than the temperature reference value TR, the internal combustion engine 6 with the starter generator 14 is started by means of a further corresponding control signal ST. Conversely, if the temperature value TW is less than the temperature reference value TR, the control unit 26 starts the internal combustion engine 6 with the starter 16 by means of a further corresponding control signal ST. In the present embodiment, the control unit 26 thereby effects a cold start (CSER) by means of corresponding control signals.

[0039] Finally, in the present embodiment, the control unit 26 is configured to read the shutdown time of the hybrid electric vehicle 2 in order to determine a cooling time AZD and to perform a warm start of the internal combustion engine 6 if the cooling time AZD is longer than a reference time RZD. In the present embodiment, the reference time RZD is one hour. Thus, a timer is started upon shutdown, i.e., upon engine stoppage, and the cooling time AZD is recorded. In a deviation from or in addition to the present embodiment, it is also possible, for example, to record an engine temperature and compare it with a threshold value.

[0040] It will now also be applied to Fig. 3 Reference is made to explain a procedure for operating the hybrid electric vehicle 2.

[0041] The process starts with a first step, S1000.

[0042] In a further step S1100, it is checked whether the hybrid electric vehicle 2 has been unlocked and / or a starter button of the hybrid electric vehicle 2 has been pressed by a driver.

[0043] When the hybrid electric vehicle 2 is unlocked and / or the starter button of the hybrid electric vehicle 2 has been pressed by the driver, in a further step S1200 the shutdown time is read in order to determine the cooling time duration AZD.

[0044] If the cooling time AZD is longer than a reference time RZD, a warm start of the internal combustion engine 6 is performed in a further step S1300.

[0045] If, however, the cooling time AZD is shorter than the reference time RZD, in a further step S1400 the battery status value BZW is compared indicatively for the state of the traction battery 28 with the battery status reference value BZR.

[0046] If the battery state value BZW is less than the battery state reference value BZR, in a further step S1500 the eEGH 20 of the hybrid electric vehicle 2 is activated.

[0047] Furthermore, in a further step, with the internal combustion engine 6 inactive, the catalyst 24 is preheated by means of a blower that is activated for 10 seconds in the present embodiment.

[0048] In a further step S1700, the internal combustion engine 6 is started with the starter generator 14, e.g. at a speed of 2000 rpm.

[0049] In a further step, S1800 activates the ignition after 2 seconds.

[0050] In a further step S1900, the internal combustion engine in the present embodiment is operated at idle until the catalyst 24 has reached a temperature of, for example, 400°C.

[0051] If, however, it was determined in step S1400 that the battery status value BZW is greater than the battery status reference value BZR, the temperature value TW is read in a further step S2800 as an indicative of an ambient temperature and compared with the temperature reference value TR.

[0052] If the temperature value TW is greater than the temperature reference value TR, the process continues with step S1700, i.e., the internal combustion engine 6 is started with the starter generator 14.

[0053] If, however, the temperature value TW is less than the temperature reference value TR, the process continues with step S2900, i.e., the internal combustion engine 6 is started with the starter 16 and the procedure then continues with step S1900.

[0054] In a further step S2000, the eEGH 20 is switched off if, in the present embodiment, it is still activated after 10 seconds.

[0055] In a further step S2100, a drive selector lever of the hybrid electric vehicle 2 is released, so that the driver can set the hybrid electric vehicle 2 in motion.

[0056] In a further step S2200, the power of the drive train 4 is reduced, in the present embodiment to 20 kW, until a predetermined catalyst temperature has been reached, in the present embodiment 600°C.

[0057] In a further step S2300, the full power of the drive train 4 is released after a predetermined period of time, in the present embodiment 10 seconds.

[0058] In a further step S2400, the traction battery 28 is charged by the generator-operated starter generator 14 until the traction battery 28 has reached a predetermined state of charge of 75% in the present embodiment.

[0059] In a further step, until the traction battery 28 reaches the predetermined state of charge of 75% in the present embodiment, motor operation of the eEGH 20 is suppressed in step S2500, but it is operated only as a generator.

[0060] The process ends with a further step S2600.

[0061] It will now also be applied to Fig. 4 Referenced to illustrate an exemplary driving cycle.

[0062] The diagram shows that during a first phase I, which can be considered a preheating phase, the catalyst 24 is preheated with the eEGh 20 and a blower activated for 10 seconds in this embodiment, while the internal combustion engine 6 is inactive. The necessary operating energy is drawn from the traction battery 28.

[0063] In a further Phase II, which can be considered a start-up phase and lasts 3 seconds in the present embodiment, the starter generator 14 starts the internal combustion engine 6, e.g. at a speed of 1500 rpm. During this Phase II, the eEGH 20 is inactive to protect the traction battery 28.

[0064] In a further phase III, which can also be regarded as a stationary heating phase, the eEGH 20 is reactivated and the operating energy is again taken from the traction battery 28.

[0065] In a further phase IV, which can also be considered a driving phase and lasts 17 seconds in the present embodiment, the eEGH 20 supports the internal combustion engine 6. The operating energy is again taken from the traction battery 28.

[0066] In a further phase V, which can also be considered a recuperation phase and lasts 300 seconds in the present embodiment, the eEGH 20 is no longer operated as a motor, but as a generator. The traction battery 28 is thus charged by the eEGH 20.

[0067] In a further phase VI, which can also be regarded as a pure combustion phase and is of indefinite length in the present embodiment, motor operation of the eEGH 20 is suppressed, but it is operated only as a generator.

[0068] In contrast to the present embodiment, the sequence of steps can also be different. Furthermore, several steps can be executed simultaneously. Additionally, in contrast to the present embodiment, individual steps can be skipped or omitted.

[0069] By using an eEGH 20, which is powered by the traction battery 28, the exhaust emissions can be reduced, especially during the start-up process of such a hybrid electric vehicle 2, since the use of the eEGH 20 allows at least one catalyst 24 of the exhaust aftertreatment system 18 of the electric hybrid vehicle 2 to reach its minimum operating temperature more quickly. Reference symbol list 2 Hybrid electric vehicles 4 Powertrain 6 Internal combustion engine 8 Clutch 10 gearboxes 12a Drive wheel 12b Drive wheel 14 Starter generator 16 starter motors 18 Exhaust aftertreatment system 20 eEGH 22a Temperature sensor 22b Temperature sensor 24 Catalyst 26 Control unit 28 traction battery 30 On-board battery 32 On-board electrical system 34a DC / DC converter 34b DC / DC converter 36 Battery Management System AZD cooling time BZR Battery State of Health Reference Value BZW battery status value RZD Reference Time Duration ST control signal TR temperature reference value TW temperature value Phase I Phase II Phase III Phase IV V Phase Phase VI S1000 step S1100 step S1200 step S1300 step S1400 step S1500 step S1600 step S1700 step S1800 step S1900 step S2000 step S2100 step S2200 step S2300 step S2400 step S2500 step S2600 step S2700 step S2800 step S2900 step

Claims

[1] Method for operating a hybrid electric vehicle (2), at least comprising the following steps: (S1400) Reading a battery state value (BSV) indicative of the state of a traction battery (28) of the hybrid electric vehicle (2) and comparing the battery state value (BSV) with a battery state reference value (BSR), and (S1500) Activating an eEGH (20) of the hybrid electric vehicle (2) when the battery state of charge (BZW) is greater than the battery state of charge reference (BZR), and / or (S2800) Reading a temperature value (TW) indicative of an ambient temperature of the hybrid electric vehicle (2) and comparing the temperature value (TW) with a temperature reference value (TR), and (S1700) Starting an internal combustion engine (6) of the hybrid electric vehicle (2) with a starter generator (14) of the hybrid electric vehicle (2) when the temperature value (TW) is less than the temperature reference value (TR), and / or (S2900) Starting an internal combustion engine (6) of the hybrid electric vehicle (2) with a starter (16) of the hybrid electric vehicle (2) when the temperature value (TW) is less than the temperature reference value (TR). [2] The method of claim 1, further comprising the steps of: (S1200) Reading a shutdown time to record a cooling time duration (CCD), and (S1300) Performing a warm start of the internal combustion engine (6) of the hybrid electric vehicle (2) when the cooling time (AZD) is longer than a reference time (RZD). [3] Method according to claim 1 or 2, wherein the battery state value (BZW) is based on the detection and evaluation of a state of charge and / or an aging state and / or a battery cell temperature and / or a health state of the traction battery (28). [4] Method according to one of claims 1 to 3, wherein a cold start is performed when starting an internal combustion engine (6) of the hybrid electric vehicle (2) using the starter (16) of the hybrid electric vehicle (2). [5] Computer program product configured to execute a method according to any one of claims 1 to 4. [6] Control unit (26) for operating a hybrid electric vehicle (2), wherein the control unit (26) is configured to read a battery state value (BZW) indicative of the state of a traction battery (28) of the hybrid electric vehicle (2) and to compare the battery state value (BZW) with a battery state reference value (BZR), to activate an eEGH (20) of the hybrid electric vehicle (2) if the battery state value (BZW) is greater than the battery state reference value (BZR), and / or to read a temperature value (TW) indicative of an ambient temperature of the hybrid electric vehicle (2) and to compare the temperature value (TW) with a temperature reference value (TR), to start an internal combustion engine (6) of the hybrid electric vehicle (2) with a starter generator (14) of the hybrid electric vehicle (2) if the temperature value (TW) is greater than the temperature reference value (TR),to start the internal combustion engine (6) of the hybrid electric vehicle (2) with a starter (16) of the hybrid electric vehicle (2) when the temperature value (TW) is less than the temperature reference value (TR). [7] Control unit (26) according to claim 6, wherein the control unit (26) is configured to read in a shutdown time in order to detect a cooling time period (CCP) and to perform a warm start of the internal combustion engine (6) of the hybrid electric vehicle (2) if the cooling time period (CCP) is longer than a reference time period (RCP). [8] Control unit (26) according to claim 6 or 7, wherein the battery status value (BZW) is based on the detection and evaluation of a state of charge and / or an aging state and / or a battery cell temperature and / or a health state of the traction battery (28). [9] Control unit (26) according to one of claims 6 to 8 wherein the control unit (26) is configured to perform a cold start when starting an internal combustion engine (6) of the hybrid electric vehicle (2) with the starter (16) of the hybrid electric vehicle (2). [10] Hybrid electric vehicle (2), with a control unit (26) according to one of claims 6 to 9

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