DESC:CROSS REFERENCE TO RELATED APPLICATION
[001] This application is based on and derives the benefit of Indian Provisional Application 201741044053, the contents of which are incorporated herein by reference.
TECHNICAL FIELD
[002] Embodiments disclosed herein relate to hybrid electric vehicles, and more particularly to cranking of the Internal Combustion (IC) engine in hybrid electric vehicles.
BACKGROUND
[003] Consider a hybrid electric vehicle where a belt starter generator (BSG), i.e. P0 machine is used. For the integration of BSG or P0 machine in FEAD (Front End Accessory Drive) of an engine, a tensioning system is required.
[004] The vehicle architecture has two prime movers for cranking engine - the BSG or a starter motor. Any one of these sources can be used to crank the engine. However, during engine crank with the starter motor or the BSG, an unpleasant sound can be observed from the FEAD. This noise is created as an after effect of torsional impact created on the tensioning system.
[005] The typical noise creating zones are shown in FIG. 1. Zone 1 noise level is lesser compared to Zone 2. This noise problem in Zone 2 can be overcome by a faster speed ramp rate during this event. But, available starter motors or BSGs are unable to provide a faster response.
[006] Also, engine cranking with a single prime mover source can lead to higher hub loads and impact torque on components connected to the FEAD system.
OBJECTS
[007] The principal object of embodiments herein is to disclose engine cranking with multiple prime mover sources simultaneously in hybrid electric vehicles.
[008] Another object of embodiments herein is to disclose engine cranking with multiple prime mover sources simultaneously in hybrid electric vehicles, hereby achieving a faster speed ramp up and reducing the noise level.
[009] Another object of embodiments herein is to disclose engine cranking with multiple prime mover sources simultaneously in hybrid electric vehicles, hereby achieving a faster speed ramp up and surpassing the torsional impact zone quickly, hereby reducing the torsional impact effect.
[0010] These and other aspects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating at least one embodiment and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.
BRIEF DESCRIPTION OF FIGURES
[0011] Embodiments herein are illustrated in the accompanying drawings, through out which like reference letters indicate corresponding parts in the various figures. The embodiments herein will be better understood from the following description with reference to the drawings, in which:
[0012] FIG. 1 depicts the engine speed profile during an engine crank;
[0013] FIG. 2 depicts a plurality of sources for cranking, according to embodiments as disclosed herein;
[0014] FIG. 3 depicts an example system, wherein the prime movers are a starter motor and a BSG motor, according to embodiments as disclosed herein; and
[0015] FIGs. 4a, 4b and 4c are example graphs depicting a torque speed profile, and engine speed profile and torsional impact during an engine crank with multiple prime movers respectively, according to embodiments as disclosed herein.

DETAILED DESCRIPTION
[0016] The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
[0017] The embodiments herein disclose engine cranking with multiple prime mover sources simultaneously in hybrid electric vehicles. Referring now to the drawings, and more particularly to FIGs. 2 to 4c, where similar reference characters denote corresponding features consistently throughout the figures, there are shown embodiments.
[0018] The vehicle as disclosed herein can be a vehicle with a hybrid powertrain, wherein at least one of the powertrain can be an electric powertrain. The vehicle further can comprise a plurality of prime movers for cranking an engine present in the vehicle.
[0019] Embodiments herein avoid or reduce noise and torsional impact effect on FEAD (Front End Accessory Drive) system components in vehicle during an engine crank event, wherein multiple sources can be used for cranking. The multiple sources can comprise of a Belt Starter Generator (BSG), and a starter motor, and are also referred to herein as prime movers. Embodiments herein also include selection of the sequence in which the prime movers are to be activated, and determining a delay for the activation of the primary movers. This delay can be chosen such way that combined effect may reduce torsional impact and reduce the noise.
[0020] FIG. 2 depicts a system for managing the cranking of an engine. The system 200, as depicted, comprises a controller unit (CU) 201 and an engine 202. A plurality of prime movers (1-n) can be connected to the engine 202 and can enable the engine 202 to crank, based on inputs from the CU 201. In an example system depicted in FIG. 3, the prime mover can be a starter motor and a BSG motor.
[0021] In an embodiment herein, the CU 201 can be a dedicated control unit, configured for selecting a sequence in which the prime movers are activated and determining a delay for the activation of the prime movers. In an embodiment herein, the CU 201 can be a control unit which performs one or other functions related to the vehicle, in addition to selecting a sequence in which the prime movers are activated/started and determining a delay for the activation of the prime movers. The CU 201 can choose the sequence and the delay, so as to reduce torsional impact and reduce the noise produced during cranking.
[0022] The CU 201 can determine a torque speed profile for the combination of prime movers available in the vehicle. The CU 101 can determine the sequence for cranking the engine using the prime movers based on the determined torque speed profile, such that a combination of the prime movers provide a reduced torsional impact and also reduce noise generated during the cranking. The CU 101 can add a time delay to at least one prime mover, such that all the prime movers do not crank at the same time. This can enable spreading out the torque speed profile, so as the torque and noise produced by each prime mover is spread over the time required for cranking the engine. The time delay can be Td ? [ 0,1]. The time delay and the sequence can be determined using experimental results.
[0023] FIG. 3 depicts an example system, wherein the prime movers are a starter motor and a BSG motor. The CU 201 can determine a torque speed profile for the starter motor and the BSG motor (as depicted in the example in FIG. 4a). The CU 101 can determine the sequence for cranking the engine using the starter motor and the BSG motor, such that a combination of the starter motor and the BSG motor provide a reduced torsional impact and also reduce noise generated during the cranking. The CU 101 can add a time delay (Td1) to the starter motor (as depicted in the example in FIG. 4b), such that the starter motor starts Td1 seconds after the BSG motor. The CU 101 can add a time delay (Td2) to the BSG (as depicted in the example in FIG. 4c), such that the BSG starts Td2 starts Td2 after the starter motor. This can enable spreading out the torque speed profile, so as the torque and noise produced by the starter motor and the BSG motor are spread over the time required for cranking the engine.
[0024] Embodiments herein provide simplicity in construction /assembly, a reduction in parts /components, a reduction in weight, efficient space management /packaging, higher reliability, and an efficient use of resources.
[0025] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
,CLAIMS:I/We claim:
1. A Control Unit (CU) (200) in a hybrid vehicle, wherein the vehicle comprises a plurality of prime movers, the CU (200) configured for:
adding a time delay to at least one prime mover, wherein activation of the at least one prime mover at engine cranking is delayed by the added time delay.
2. The CU, as claimed in claim 1, wherein the plurality of prime movers is at least one of a starter motor, and a Belt Starter Generator (BSG).
3. The CU, as claimed in claim 1, wherein the CU (201) is configured to
determine a torque speed profile for the plurality of prime movers; and
determining the time delay based on the determined torque speed profile.
4. The CU, as claimed in claim 1, wherein the added time delay reduces torsional impact during engine cranking.
5. The CU, as claimed in claim 1, wherein the added time delay reduces noise during engine cranking.