Power train of plug-in hybrid vehicle using multi-functional starter-generator and control method thereof

Abstract

The present invention relates to a power train of a plug-in hybrid vehicle using a multi-functional starter generator, and a control method using same, the power train of a plug-in hybrid vehicle comprising: an internal combustion engine unit (1); a motor-generator unit (2); a clutch unit (3); a transmission unit (4); a differential unit (5); a starter-generator unit (6); and a battery unit (8) connected to each of the motor-generator unit (2) and the starter-generator unit (6) through an inverter unit (7), wherein a first gear (12) is provided on an output shaft (11) of the internal combustion engine unit (1), a second gear (14) is provided on an input shaft (13) of the motor-generator unit (2), first and second dog clutches (21, 23) and third and fourth gears (22, 24) individually engaged with the first and second gears (12, 14) are provided on a driving shaft (25) of the starter-generator unit (6), the first dog clutch (21) connects or disconnects the driving shaft (25) of the starter-generator unit (6) to or from the output shaft (11) of the internal combustion engine unit (1) when the driving shaft (25) of the starter-generator unit (6) is synchronized with the output shaft (11) of the internal combustion engine unit (1), and the second dog clutch (23) connects or disconnects the driving shaft (25) of the starter-generator unit (6) to or from the input shaft (13) of the motor-generator unit (2) when the driving shaft (25) of the starter-generator unit (6) is synchronized with the input shaft (13) of the motor-generator unit (2).

Description

Powertrain of a plug-in hybrid vehicle using a multi-function starter-generator and its control method

[0001] The present invention relates to a powertrain of a plug-in hybrid vehicle and a control method thereof, and more particularly, to a powertrain of a plug-in hybrid vehicle using a multi-functional starter-generator that can sufficiently generate the output required for driving a vehicle even without installing a large-capacity motor-generator, and can ensure higher energy efficiency, and further, can provide higher power generation efficiency by installing a high-performance, large-capacity starter-generator, and a control method thereof.

[0002] With the global push for carbon neutrality and the subsequent cessation of production of internal combustion engine vehicles in response to environmental pollution caused by fossil fuel use, research and development on eco-friendly electric vehicles and the production of more efficient, larger-capacity batteries to power them are emerging as global concerns.

[0003] Meanwhile, hybrid vehicles have been proposed and are widely used to overcome the problems inherent in internal combustion engine vehicles and the limitations of currently available electric vehicles. Hybrid vehicles, a hybrid vehicle that combines the advantages of internal combustion engine vehicles and electric vehicles, were developed to improve fuel efficiency while minimizing environmental pollution.

[0004] A hybrid vehicle, as shown in an example in Fig. 7, adds a motor-generator (3) to an internal combustion engine (1) to drive the vehicle, and can recover and use kinetic energy wasted during the driving process as electrical energy using the motor-generator (3). Generally, the vehicle operates by using the motor-generator (3) as a power source when starting from a standstill or driving at low speeds, and using the internal combustion engine (1) as a power source when high output is required, such as driving at high speeds.

[0005] In this way, hybrid vehicles can provide improved fuel efficiency by selectively using the motor-generator and internal combustion engine depending on the driving conditions, and at the same time, they have the advantage of minimizing environmental pollution by being able to operate the vehicle through the motor-generator operated by the battery, but they have the disadvantage of being unable to operate the vehicle itself when the fuel that operates the internal combustion engine is exhausted.

[0006] Plug-in hybrid vehicles have been proposed to improve upon the shortcomings of traditional hybrid vehicles. Unlike typical hybrid vehicles, plug-in hybrid vehicles are designed to charge their batteries from an external power source. When the fuel runs out and the internal combustion engine is no longer capable of driving, the motor-generator uses the stored electric energy to drive the vehicle for a certain distance.

[0007] Meanwhile, plug-in hybrid vehicles must operate in electric vehicle mode (electric vehicle) driven by the motor-generator even at medium or higher speeds, so they are generally equipped with larger motor-generators than traditional hybrid vehicles. As the capacity of the motor-generator increases, the generator and battery also have relatively larger capacities. However, as the capacities of the motor-generator, generator, and battery increase, the weight of the vehicle itself increases, which leads to a problem of reduced fuel efficiency.

[0008] In addition, when the battery is discharged, the internal combustion engine operates to drive the heavy vehicle and rotate the generator to charge the battery, so not only is the fuel efficiency lower than that of a traditional hybrid vehicle, but the amount of exhaust gas emitted due to the consumption of fossil fuels also increases. In addition, because the starter generator (6) itself is connected to the internal combustion engine (1) as shown in Fig. 7 due to the nature of the hybrid vehicle, there was a problem that even when the starter generator (6) did not operate, it acted as passive resistance when the internal combustion engine (1) was in operation, further reducing the fuel efficiency.

[0009] The present invention has been proposed to improve the problems of the prior art, and the purpose of the present invention is to provide a powertrain of a plug-in hybrid vehicle and a control method thereof, which can drive with optimal fuel efficiency depending on the driving situation by configuring a starter-generator to perform multiple functions.

[0010] In order to achieve this purpose, the present invention provides a powertrain of a plug-in hybrid vehicle, which includes an internal combustion engine unit (1), a motor-generator unit (2) arranged horizontally with the internal combustion engine unit (1), a clutch unit (3) interposed between an output shaft (11) of the internal combustion engine unit (1) and an input shaft (13) of the motor-generator unit (2), a transmission unit (4) connected to the output shaft (15) of the motor-generator (2), a differential unit (5) connected to the output shaft (16) of the transmission unit (4), a starter-generator unit (6) arranged on one side of the internal combustion engine unit (1), and a battery unit (8) interposed with an inverter unit (7) and connected to each of the motor-generator unit (2) and the starter-generator unit (6), wherein a first gear (12) is provided on the output shaft (11) of the internal combustion engine unit (1), and a second gear (14) is provided on the input shaft (13) of the motor-generator unit (2). A first and second dog clutches (21, 23) and a third and fourth gears (22, 24) that mesh with the first and second gears (12, 14) are provided on the drive shaft (25) of the starter-generator unit (6), respectively; the first dog clutch (21) connects the drive shaft (25) of the starter-generator unit (6) to the output shaft (11) of the internal combustion engine unit (1) or disconnects the connected state when the drive shaft (25) of the starter-generator unit (6) is synchronized with the output shaft (11) of the internal combustion engine unit (1); The above second dog clutch (23) is characterized by connecting or disconnecting the drive shaft (25) of the starter-generator unit (6) with the input shaft (13) of the motor-generator unit (2) when the drive shaft (25) of the starter-generator unit (6) is synchronized with the input shaft (13) of the motor-generator unit (2).

[0011] A first idling gear (31) and a second idling gear (33) may be provided between the first and third gears (12, 22) and between the second and fourth gears (14, 24), respectively, or a pair of third and fourth idling gears (35, 36) that mesh with each other may be provided between the second and fourth gears (14, 24).

[0012] The drive shaft (25) of the above starter-generator unit (6) is composed of first and second drive shafts (26, 27) that form a coaxial axis, the internal combustion engine unit (1) is provided with an auxiliary output shaft (17) that forms a coaxial axis with the output shaft (11), the first gear (12) is provided on the auxiliary output shaft (17) of the internal combustion engine unit (1), the third gear (22) and the first door clutch (21) are each provided on the first drive shaft (26) of the starter-generator unit (6), and the fourth gear (24) and the second dog clutch (23) are each provided on the second drive shaft (27) of the starter-generator unit (6); A first idling gear (31) and a second idling gear (33) may be provided between the first and third gears (12, 22) and between the second and fourth gears (14, 24), respectively, or a pair of third and fourth idling gears (35, 36) that mesh with each other may be provided between the second and fourth gears (14, 24).

[0013] Another technical feature of the present invention is that, when the operating power charged in the battery unit (8) is sufficient, the standby mode of the vehicle is achieved in such a way that the operation of the internal combustion engine unit (1) and the motor-generator unit (2) is stopped while the connection of the clutch unit (3) and the first dog clutch (21) is released and the second dog clutch (23) is connected; and the first electric vehicle mode of the vehicle is achieved in such a way that the rotational power generated in the motor-generator unit (2) is transmitted to the transmission unit (4) and the differential unit (5) while the connection of the clutch unit (3) and the first and second dog clutches (21, 23) is released and the operation of the internal combustion engine unit (1) is stopped; The second electric vehicle mode of the automobile is achieved by disengaging the clutch unit (3) and the first dog clutch (21), stopping the operation of the internal combustion engine unit (1), operating the second dog clutch (23), and transmitting the rotational power generated in each of the starter-generator unit (6) and the motor-generator unit (2) to the transmission unit (4) and the differential unit (5) while the drive shaft (25) of the starter-generator unit (6) is connected to the input shaft (13) of the motor-generator unit (2); The parallel mode of the automobile is implemented in such a way that the drive shaft (25) of the first dog clutch (21) and the output shaft (11) of the internal combustion engine (1) are connected by the operation of the first dog clutch (21), and when the internal combustion engine (1) is operated, the first dog clutch (21) is operated again to release the connection between the drive shaft (25) of the first dog clutch (21) and the output shaft (11) of the internal combustion engine (1), and the rotational power generated in each of the internal combustion engine (1) and the motor-generator (6) in a state where the clutch (3) is connected is transmitted to the transmission (4) and the differential (5); the first regenerative power generation mode of the automobile is implemented in such a way that the motor-generator (6) generates power alone in a state where the clutch (3) and the first and second dog clutches (21, 23) are released;The second regenerative power generation mode of the vehicle is achieved in such a way that the starter-generator unit (6) and the motor-generator unit (6) generate power while the clutch unit (3) is released and the drive shaft (25) of the starter-generator unit (6) and the input shaft (13) of the motor-generator unit (6) are connected by the operation of the second dog clutch (23); when the operating power charged in the battery unit (8) is insufficient, the standby mode of the vehicle is achieved in such a way that the clutch unit (3) and the second dog clutch (23) are released and the operation of the internal combustion engine unit (1) and the motor-generator unit (2) is stopped while the first dog clutch (21) is connected; The electric vehicle mode of the automobile is achieved in such a way that the clutch unit (3) and the first and second dog clutches (23) are each disconnected, the operation of the internal combustion engine unit (1) is stopped, and the rotational power generated in the motor-generator unit (2) is transmitted to the transmission unit (4) and the differential unit (5); the real-time series mode of the automobile is achieved in such a way that the clutch unit (3) and the second dog clutch (23) are each disconnected, the drive shaft (25) of the first dog clutch (21) and the output shaft (11) of the internal combustion engine unit (1) are connected by the operation of the first dog clutch (21), and the internal combustion engine unit (1) is operated, the starter-generator unit (6) generates power by the internal combustion engine unit (1), and the rotational power generated in the motor-generator unit (2) is transmitted to the transmission unit (4) and the differential unit (5); In the driving stop mode and the coasting mode of the vehicle, each of the clutch unit (3) and the second dog clutch (23) is released, and the drive shaft (25) of the starter-generator unit (6) and the output shaft (11) of the internal combustion engine unit (1) are connected by the operation of the first dog clutch (21), so that the internal combustion engine unit (1) is operated, and the starter-generator unit (6) generates power by the internal combustion engine unit (1), and the motor-generator unit (2) rotates passively;The first parallel mode of the vehicle is achieved in such a manner that the first and second dog clutches (21, 23) are each disconnected, the clutch unit (3) is connected, and the rotational power generated in the internal combustion engine unit (1) is transmitted to the transmission unit (4) and the differential unit (5) via the motor-generator unit (2) that rotates passively; the second parallel mode of the vehicle is achieved in such a manner that the first and second dog clutches (21, 23) are each disconnected, the clutch unit (3) is connected, and the rotational power generated in the internal combustion engine unit (1) and the motor-generator unit (2) is transmitted to the transmission unit (4) and the differential unit (5); The parallel third mode of the vehicle is achieved in such a way that the first and second dog clutches (21, 23) are each disengaged, the clutch unit (3) is engaged, and the rotational power generated in the internal combustion engine unit (1) is transmitted to the transmission unit (4) and the differential unit (5) via the motor-generator unit (2) which rotates passively, and the motor-generator unit (2) generates power; the series-parallel mode of the vehicle is achieved in such a way that the second dog clutch (23) is disengaged, the first dog clutch (21) is operated to connect the drive shaft (25) of the starter-generator unit (6) with the output shaft (11) of the internal combustion engine unit (1), and the starter-generator unit (6) generates power, the clutch unit (3) is engaged, and the rotational power generated in each of the internal combustion engine unit (1) and the motor-generator unit (2) is transmitted to the transmission unit (4) and the differential unit (5); The first mode of regenerative power generation of the vehicle is achieved in such a way that the motor-generator unit (6) generates power solely while the clutch unit (3) and the first and second dog clutches (21, 23) are each released; the second mode of regenerative power generation of the vehicle is achieved in such a way that the clutch unit (3) is released, the second dog clutch (23) is operated, and the drive shaft (25) of the starter-generator unit (6) and the input shaft (13) of the motor-generator unit (2) are connected while the starter-generator unit (6) and the motor-generator unit (6) each generate power;

[0014] The present invention configures a starter-generator drive shaft to be selectively connected or disconnected to each of an output shaft of an internal combustion engine and an input shaft of a motor-generator using a dog clutch, so that the starter-generator can be used as an auxiliary power source, thereby generating the output necessary for driving a vehicle even without installing a large-capacity motor-generator, and ensuring higher energy efficiency by reducing the load caused by the passive rotation of the starter-generator when the internal combustion engine is operating. Furthermore, it can provide higher power generation efficiency by allowing a high-performance, large-capacity starter-generator to be installed.

[0015] FIG. 1 is a diagram illustrating a powertrain configuration in a plug-in hybrid vehicle as an example according to the present invention.

[0016] FIGS. 2 to 5 each illustrate a configuration of a powertrain in a plug-in hybrid vehicle as another example according to the present invention.

[0017] FIG. 6 is a diagram showing the configuration of a powertrain in a plug-in hybrid vehicle as another example according to the present invention.

[0018] Figure 7 is a schematic diagram of a conventional hybrid vehicle.

[0019] A preferred embodiment of the present invention will be described in detail with reference to the attached drawings as follows. In describing the embodiment of the present invention, a detailed description of matters that are not directly related to the technical features of the present invention or are obvious to a person having ordinary skill in the technical field to which the present invention pertains will be omitted.

[0020] The present invention relates to a powertrain of a plug-in hybrid vehicle and a control method thereof. In the present invention, the powertrain has a technical characteristic that it comprises an internal combustion engine section (1), a motor-generator section (2), a clutch section (3), a transmission section (4), a differential section (5), a starter-generator section (6), a battery section (8), and first to fourth gears (12, 14, 22, 24) and first and second dog clutches (21, 23), as disclosed in FIG. 1.

[0021] The internal combustion engine section (1) and the motor-generator section (2) are each a section that generates rotational power and are arranged horizontally to each other. It is preferable that the output shaft (11) of the internal combustion engine section (1) and the input shaft (13) of the motor-generator section (2) are coaxial. The internal combustion engine section (1) and the motor-generator section (2) may each be formed of a conventional engine and a drive motor that use fossil fuels and power sources, respectively.

[0022] The clutch unit (3) is a means for transmitting or disconnecting the rotational power generated in the internal combustion engine unit (1) to the motor-generator unit (2), and is interposed between the output shaft (11) of the internal combustion engine unit (1) and the input shaft (13) of the motor-generator unit (2). The clutch unit (3) may be formed of any one of the clutches widely used in the relevant industry.

[0023] The transmission unit (4) is a unit that appropriately converts the rotational power generated and transmitted from the motor-generator unit (2) or the internal combustion engine unit (1) and the motor-generator unit (2) according to the driving conditions of the vehicle, and is connected to the output shaft (15) of the motor-generator (2). The transmission unit (4) may be configured as a conventional multi-stage transmission device. The differential unit (5) is a unit that operates the wheels using the rotational power converted by the transmission unit (4), and is connected to the output shaft (16) of the transmission unit (4).

[0024] The starter-generator unit (6) is a unit that operates the internal combustion engine unit (1), generates power, and further generates rotational power, and is arranged on one side of the internal combustion engine unit (1). That is, in the present invention, unlike a conventional starter-generator that simply operates the internal combustion engine unit (1), the starter-generator unit (6) has the characteristic of being able to perform regenerative power generation as well as assisting the motor-generator unit (2) and providing rotational power. A detailed description thereof will be provided later.

[0025] The battery section (8) is connected to the inverter section (7) and the motor-generator section (2) and the starter-generator section (6), respectively. The unexplained drawing reference numeral 9 is a charging cable, and a conventional charger (not shown) is provided in the battery section (8).

[0026] The first gear (12) is provided on the output shaft (11) of the internal combustion engine section (1), and the second gear (14) is provided on the input shaft (13) of the motor-generator section (2). In addition, the third and fourth gears (22, 24) are each provided on the drive shaft (25) of the starter-generator section (6). At this time, the third gear (22) is engaged with the first gear (12), and the fourth gear (24) is engaged with the second gear (14).

[0027] The first and second dog clutches (21, 23) are each a part that synchronizes the drive shaft (25) of the starter-generator unit (6) with the output shaft (11) of the internal combustion engine unit (1) and the drive shaft (25) of the starter-generator unit (6) with the input shaft (13) of the motor-generator unit (2). The operation of each of the first and second dog clutches (21, 23) can be controlled by a controller (not shown).

[0028] That is, when the rotational speed of the drive shaft (25) of the starter-generator unit (6) is synchronized with the output shaft (11) of the internal combustion engine unit (1) or the input shaft (13) of the motor-generator unit (2), either one or both of the first and second dog clutches (21, 23) are controlled by the controller and naturally connected.

[0029] In this case, the internal combustion engine section (1) can be operated by the starter-generator section (6) as in the past, and can function as a power generation means and an auxiliary power means, respectively, and the phenomenon of the starter-generator section (6) acting as a passive load during the operation of the internal combustion engine section (1) and reducing the output can be fundamentally prevented.

[0030] Meanwhile, the present invention does not exclude a case where the clutch part (3) is provided coaxially inside the motor-generator part (2) as shown in Fig. 6 when mediating the clutch part (3) between the internal combustion engine part (1) and the motor-generator part (2).

[0031] This embodiment is different from the embodiment of Fig. 1 described above in that the clutch unit (3) is provided at the end of the output shaft (11) of the internal combustion engine unit (1) to connect the power generated in the internal combustion engine unit (1) to the output shaft (15) of the motor-generator unit (2), or to disconnect the output shaft (11) of the connected internal combustion engine unit (1) and the output shaft (15) of the motor-generator unit (2).

[0032] In this way, by arranging the clutch unit (3) coaxially with the motor-generator unit (2), it is possible to design the internal space of the electric vehicle more efficiently, as the size of the powertrain itself can be significantly reduced. The configuration is essentially the same in that the second gear (14) is connected to the input shaft (13) of the motor-generator unit (2).

[0033] Meanwhile, when synchronizing the starter-generator unit (6) with the internal combustion engine unit (1) or the motor-generator unit (2) using the first and second dog clutches (21, 23), respectively, by appropriately adjusting the gear ratios of the first and third gears (12, 22) and the second and fourth gears (14, 24) that are engaged as disclosed in FIG. 1, it is possible to use it as a more efficient power generation and motive power means, and the size of the gears themselves can be reduced.

[0034] Examples of this are disclosed in FIGS. 2 to 5, respectively. First, FIG. 2 shows a case where a pair of third and fourth idling gears (35, 36) that mesh with each other are provided between the second and fourth gears (14, 24), and FIG. 3 shows a case where a first idling gear (31) and a second idling gear (33) are provided between the first and third gears (12, 22) and between the second and fourth gears (14, 24), respectively.

[0035] In contrast, each of FIGS. 4 and 5 shows a case where the drive shaft (25) of the starter-generator unit (6) itself is configured separately as the first and second drive shafts (26, 27) that form a coaxial connection, and the auxiliary output shaft (17) that forms a coaxial connection with the output shaft (11) of the internal combustion engine unit (1) is separately configured, and the first to fourth gears (12, 14, 22, 24) and the first and second dog clutches (21, 23) are arranged, respectively.

[0036] More specifically, the first gear (12) is provided on the auxiliary output shaft (17) of the internal combustion engine section (1), the third gear (22) and the first door clutch (21) are each provided on the first drive shaft (26) of the starter-generator (6), and the fourth gear (24) and the second dog clutch (23) are each provided on the second drive shaft (27) of the starter-generator (6).

[0037] In this way, with the first to fourth gears (12, 14, 22, 24) and the first and second dog clutches (21, 23) respectively arranged, FIG. 4 shows a case where a pair of third and fourth idling gears (35, 36) that mesh with each other are provided between the second and fourth gears (14, 24), and FIG. 5 shows a case where a first idling gear (31) and a second idling gear (33) are provided between the first and third gears (12, 22) and between the second and fourth gears (14, 24), respectively.

[0038] It is obvious that the gear ratios disclosed in each drawing are not uniformly determined, but can be varied in various ways depending on the specific capacities of the internal combustion engine section (1), the motor-generator section (2), and the starter-generator section (6), and the combination of idling gears disclosed in each of FIGS. 2 to 5 can be appropriately changed and applied in a similar manner even when the clutch section (3) is provided coaxially inside the motor-generator section (2) as in FIG. 6.

[0039] Next, a specific control method for the powertrain of a plug-in hybrid vehicle with such a configuration will be examined with reference to the aforementioned description and the attached drawings. Since the present invention relates to a plug-in hybrid vehicle, the control method may vary depending on the remaining charge in the battery unit (8). Therefore, the case where the operating power charged in the battery unit (8) is sufficient will be examined first.

[0040] The standby mode of the vehicle can be achieved by disengaging the clutch unit (3) and the first dog clutch (21), respectively, and stopping the operation of the internal combustion engine unit (1) and the motor-generator unit (2) while the second dog clutch (23) is connected. This standby mode corresponds to the stage before the vehicle is driven.

[0041] The electric vehicle mode of a vehicle that runs using the operating power of the battery unit (8) can be implemented in one of two ways. Among them, the first mode can be implemented in a manner in which the rotational power generated in the motor-generator unit (2) is transmitted to the transmission unit (4) and the differential unit (5) while the clutch unit (3) and the first and second dog clutches (21, 23) are each disconnected and the operation of the internal combustion engine unit (1) is stopped.

[0042] And, another second mode can be achieved in such a way that the connection of the clutch unit (3) and the first dog clutch (21) is released, the operation of the internal combustion engine unit (1) is stopped, and the second dog clutch (23) is operated to connect and synchronize the drive shaft (25) of the starter-generator unit (6) with the input shaft (13) of the motor-generator unit (6), and the rotational power generated in each of the starter-generator unit (6) and the motor-generator unit (2) is transmitted to the transmission unit (4) and the differential unit (5).

[0043] Looking at these modes, the difference is that in the first mode, the car runs solely with the output of the motor-generator unit (2), and in the second mode, the car runs with the combined output of the starter-generator unit (6) and the motor-generator unit (2). In cases where low output is required, such as when starting off or at low speeds, the first mode is suitable, and in cases where high output is required, such as when driving at high speeds or rapid acceleration, the second mode is suitable.

[0044] Conventional plug-in hybrid vehicles typically utilize a large motor-generator to operate in electric mode, utilizing the operating power stored in the battery. However, installing a relatively heavy motor-generator can reduce efficiency (fuel efficiency) in electric mode due to the increased weight. Furthermore, when the battery is depleted and the vehicle switches to hybrid mode, fuel economy drops.

[0045] However, the present invention can secure sufficiently high output in electric vehicle mode even when a motor-generator unit (2) having a relatively small capacity compared to the prior art is installed by configuring the starter-generator unit (6) to be involved in electric vehicle driving by operating the second dog clutch (23) as needed, and can also help improve fuel efficiency during driving by reducing the weight of the vehicle itself.

[0046] The parallel mode of an automobile in which an internal combustion engine section (1) and a motor-generator section (2) are involved simultaneously can be achieved in a manner in which the rotational power generated in each of the internal combustion engine section (1) and the motor-generator section (6) is transmitted to the transmission section (4) and the differential section (5) while the clutch section (3) is connected.

[0047] At this time, the internal combustion engine unit (1) is started by being operated by the first dog clutch (21), and when the internal combustion engine unit (1) is operated, the connection with the first dog clutch (21) is released. That is, the first dog clutch (21) is operated to connect the drive shaft (25) of the first dog clutch (21) with the output shaft (11) of the internal combustion engine unit (1), thereby operating the internal combustion engine unit (1), and then the first dog clutch (21) is operated again to release the connection between the drive shaft (25) of the first dog clutch (21) and the output shaft (11) of the internal combustion engine unit (1).

[0048] In conventional plug-in hybrid vehicles, the starter-generator is always connected to the internal combustion engine. Therefore, while the starter-generator may generate power when the internal combustion engine is operating, there is a problem in that when it is passively rotating without generating power, it eats up the output of the internal combustion engine. However, this problem does not occur at all in the present invention because the starter-generator unit (6) can be disconnected from the internal combustion engine unit (1) using the first dog clutch (21).

[0049] Therefore, when comparing the present invention with a conventional plug-in hybrid vehicle while the vehicle is driven in parallel mode, it is clear that the fuel efficiency and electric energy efficiency can be relatively improved when the internal combustion engine and motor-generator each have the same capacity.

[0050] The regenerative power generation mode for charging the battery unit (8) while the vehicle is driving can also be operated in two ways. The first mode is a method in which the motor-generator unit (6) generates power solely while the clutch unit (3) and the first and second dog clutches (21, 23) are released, and the other, the second mode, can be a method in which the starter-generator unit (6) and the motor-generator unit (6) generate power while the clutch unit (3) is released and the second dog clutch (23) is connected.

[0051] That is, the first mode is when the motor-generator section (6) generates the rotational power transmitted from the differential section (5) alone, and the second mode is when the starter-generator section (6) and the motor-generator section (6) each generate power together. In the case of rapid charging, the second mode is advantageous, and in order to apply the second mode, the second dog clutch (23) must be operated so that the starter-generator section (6) connects the drive shaft (25) in synchronization with the input shaft (13) of the motor-generator section (6).

[0052] Next, let us examine the case where the operating power charged in the battery section (8) is insufficient.

[0053] The standby mode of the vehicle can be achieved by disengaging the clutch unit (3) and the second dog clutch (23), respectively, and stopping the operation of the internal combustion engine unit (1) and the motor-generator unit (2). At this time, the first dog clutch (21) operates, thereby connecting the drive shaft (25) of the starter-generator unit (6) and the output shaft (11) of the internal combustion engine unit (1).

[0054] The electric vehicle mode of the vehicle can be achieved by disengaging the clutch unit (3) and the first and second dog clutches (23), stopping the operation of the internal combustion engine unit (1), and transmitting the rotational power generated by the motor-generator unit (2) to the transmission unit (4) and the differential unit (5). Since the remaining battery capacity (8) is insufficient, it is suitable for starting or low-speed driving.

[0055] The real-time series mode of the automobile can be achieved in such a way that the clutch unit (3) and the second dog clutch (23) are each disconnected, the starter-generator unit (6) generates power by the internal combustion engine unit (1), and the rotational power generated in the motor-generator unit (2) is transmitted to the transmission unit (4) and the differential unit (5). In order for the starter-generator unit (6) to generate power, the first dog clutch (21) needs to be operated so that the drive shaft (25) of the first dog clutch (21) is connected to the output shaft (11) of the internal combustion engine unit (1).

[0056] In this way, the present invention can connect or disconnect the drive shaft (25) of the starter-generator unit (6) with the output shaft (11) of the internal combustion engine unit (1) using the first dog clutch (21), thereby preventing the output of the internal combustion engine unit (1) from being consumed by the starter-generator unit (6) when power generation is not taking place. Therefore, unlike in the past, it is possible to install a large-capacity starter-generator capable of the most efficient power generation.

[0057] The driving mode and coasting mode of the vehicle can be achieved in such a manner that the clutch unit (3) and the second dog clutch (23) are each released, the starter-generator unit (6) generates power by the internal combustion engine unit (1), and the motor-generator unit (2) rotates passively. Since the vehicle is in a state of coasting by inertia, the involvement of the internal combustion engine unit (1) and the motor-generator unit (2) is not necessary. The drive shaft (25) of the starter-generator unit (6) is connected to the output shaft (11) of the internal combustion engine unit (1) by the operation of the first dog clutch (21).

[0058] When the remaining capacity of the battery unit (8) is insufficient, the parallel mode of the vehicle can be implemented in one of the following three ways. First, the first mode can be implemented in such a way that the first and second dog clutches (21, 23) are each disconnected, the clutch unit (3) is connected, and the rotational power generated in the internal combustion engine unit (1) is transmitted to the transmission unit (4) and the differential unit (5) via the motor-generator unit (2) that rotates passively.

[0059] And, the second mode can be achieved in such a way that the first and second dog clutches (21, 23) are each disconnected, the clutch unit (3) is connected, and the rotational power generated in each of the internal combustion engine unit (1) and the motor-generator unit (2) is transmitted to the transmission unit (4) and the differential unit (5).

[0060] Lastly, the third mode can be achieved in such a way that the first and second dog clutches (21, 23) are each disconnected, the clutch unit (3) is connected, the rotational power generated in the internal combustion engine unit (1) is transmitted to the transmission unit (4) and the differential unit (5) via the passively rotating motor-generator unit (2), and the motor-generator unit (2) generates power.

[0061] To summarize the characteristics of each of these modes, in each of the first and third modes, the motor-generator section (2) rotates passively, and in the second mode, the motor-generator section (2) also generates output using the power of the battery section (8). However, the third mode differs from the first mode in that it generates power using the rotational power transmitted from the internal combustion engine section (1) and charges the battery section (8).

[0062] Meanwhile, in each of these parallel modes, the connection of the first dog clutch (21) is released, in which case the starter-generator unit (6) is disconnected from the drive shaft (25) and the output shaft (11) of the internal combustion engine unit (1). Therefore, when the internal combustion engine unit (1) is in operation, the problem of the output of the internal combustion engine unit (1) being consumed due to the passive rotation of the starter-generator unit (6) does not occur, and thus fuel efficiency can be improved compared to the past.

[0063] The series-parallel mode of the automobile can be achieved in such a way that the second dog clutch (23) is released, the starter-generator unit (6) generates power, the clutch unit (3) is connected, and the rotational power generated in each of the internal combustion engine unit (1) and the motor-generator unit (2) is transmitted to the transmission unit (4) and the differential unit (5). The power generation of the starter-generator unit (6) is possible by connecting the drive shaft (25) of the starter-generator unit (6) to the output shaft (11) of the internal combustion engine unit (1) through the operation of the first dog clutch (21).

[0064] The regenerative power generation mode for charging the battery unit (8) while the vehicle is driving can be operated in two separate modes: a first mode in which the motor-generator unit (6) generates power solely while the clutch unit (3) and the first and second dog clutches (21, 23) are released, and a second mode in which the clutch unit (3) is released, the second dog clutch (23) is operated, and the drive shaft (25) of the starter-generator unit (6) and the input shaft (13) of the motor-generator unit (2) are connected, and the starter-generator unit (6) and the motor-generator unit (6) generate power respectively.

[0065] Each of these regenerative power generation modes in a state where the battery section (8) has insufficient remaining capacity is similar to the case where the battery section (8) has sufficient remaining capacity, and it is obvious that the second mode in which the starter-generator section (6) and the motor-generator section (6) generate power together is advantageous when rapid charging is required.

[0066] Although the above description is limited to preferred embodiments of the present invention, this is merely an example, and the present invention is not limited thereto, and can be implemented by being modified in various ways, and further, it will be obvious that separate technical features can be added and implemented based on the disclosed technical idea.

[0067] The present invention can generate the output required for driving a vehicle even without installing a large-capacity motor-generator, and can reduce the load caused by the passive rotation of a starter-generator during the operation of an internal combustion engine, so that it can be widely applied to the powertrain of a plug-in hybrid vehicle that is configured and operated by a combination of an internal combustion engine and a motor-generator, and its control method.

Claims

1. A powertrain of a plug-in hybrid vehicle, comprising an internal combustion engine section (1), a motor-generator section (2) arranged horizontally with the internal combustion engine section (1), a clutch section (3) interposed between an output shaft (11) of the internal combustion engine section (1) and an input shaft (13) of the motor-generator section (2), a transmission section (4) connected to an output shaft (15) of the motor-generator (2), a differential section (5) connected to an output shaft (16) of the transmission section (4), a starter-generator section (6) arranged on one side of the internal combustion engine section (1), and a battery section (8) interposed to an inverter section (7) and connected to each of the motor-generator section (2) and the starter-generator section (6). A first gear (12) is provided on the output shaft (11) of the internal combustion engine section (1), a second gear (14) is provided on the input shaft (13) of the motor-generator section (2), and a third and fourth gears (22, 24) are provided on the drive shaft (25) of the starter-generator section (6) to mesh with the first and second dog clutches (21, 23) and the first and second gears (12, 14), respectively; The above first dog clutch (21) connects the drive shaft (25) of the starter-generator unit (6) to the output shaft (11) of the internal combustion engine unit (1) or disconnects the connection when the drive shaft (25) of the starter-generator unit (6) is synchronized with the output shaft (11) of the internal combustion engine unit (1); A powertrain of a plug-in hybrid vehicle using a multi-functional starter-generator, characterized in that the second dog clutch (23) connects or disconnects the drive shaft (25) of the starter-generator unit (6) from the input shaft (13) of the motor-generator unit (2) when the drive shaft (25) of the starter-generator unit (6) is synchronized with the input shaft (13) of the motor-generator unit (2).

2. In paragraph 1, A powertrain of a plug-in hybrid vehicle using a multi-functional starter-generator, characterized in that a first idling gear (31) and a second idling gear (33) are provided between the first and third gears (12, 22) and between the second and fourth gears (14, 24), or a pair of third and fourth idling gears (35, 36) that mesh with each other are provided between the second and fourth gears (14, 24).

3. In paragraph 1, The drive shaft (25) of the above starter-generator unit (6) is composed of first and second drive shafts (26, 27) that form a coaxial axis, the internal combustion engine unit (1) is provided with an auxiliary output shaft (17) that forms a coaxial axis with the output shaft (11), the first gear (12) is provided on the auxiliary output shaft (17) of the internal combustion engine unit (1), the third gear (22) and the first door clutch (21) are each provided on the first drive shaft (26) of the starter-generator unit (6), and the fourth gear (24) and the second dog clutch (23) are each provided on the second drive shaft (27) of the starter-generator unit (6); A powertrain of a plug-in hybrid vehicle using a multi-functional starter-generator, characterized in that a first idling gear (31) and a second idling gear (33) are provided between the first and third gears (12, 22) and between the second and fourth gears (14, 24), respectively, or a pair of third and fourth idling gears (35, 36) that mesh with each other are provided between the second and fourth gears (14, 24).

4. If the operating power charged in the battery compartment (8) is sufficient, The standby mode of the vehicle is achieved by disengaging the clutch unit (3) and the first dog clutch (21), respectively, and stopping the operation of the internal combustion engine unit (1) and the motor-generator unit (2) while the second dog clutch (23) is connected; The first electric vehicle mode of the automobile is achieved by disengaging the clutch unit (3) and the first and second dog clutches (21, 23), respectively, and transmitting the rotational power generated in the motor-generator unit (2) to the transmission unit (4) and differential unit (5) while the internal combustion engine unit (1) is stopped; The second electric vehicle mode of the automobile is achieved by disengaging the clutch unit (3) and the first dog clutch (21), stopping the operation of the internal combustion engine unit (1), operating the second dog clutch (23), and transmitting the rotational power generated in each of the starter-generator unit (6) and the motor-generator unit (2) to the transmission unit (4) and the differential unit (5) while the drive shaft (25) of the starter-generator unit (6) is connected to the input shaft (13) of the motor-generator unit (2); The parallel mode of the automobile is achieved by the operation of the first dog clutch (21) so that the drive shaft (25) of the first dog clutch (21) and the output shaft (11) of the internal combustion engine (1) are connected, and when the internal combustion engine (1) is operated, the first dog clutch (21) is operated again to release the connection between the drive shaft (25) of the first dog clutch (21) and the output shaft (11) of the internal combustion engine (1), and the rotational power generated in each of the internal combustion engine (1) and the motor-generator (6) while the clutch (3) is connected is transmitted to the transmission (4) and the differential (5); The first mode of regenerative power generation of the automobile is performed in a manner in which the motor-generator unit (6) generates power solely while the clutch unit (3) and the first and second dog clutches (21, 23) are released; The second regenerative power generation mode of the automobile is achieved in such a way that the starter-generator unit (6) and the motor-generator unit (6) each generate power while the clutch unit (3) is released and the drive shaft (25) of the starter-generator unit (6) and the input shaft (13) of the motor-generator unit (6) are connected by the operation of the second dog clutch (23); If the operating power charged in the battery compartment (8) is insufficient, The standby mode of the vehicle is achieved by disengaging the clutch unit (3) and the second dog clutch (23), respectively, and stopping the operation of the internal combustion engine unit (1) and the motor-generator unit (2) while the first dog clutch (21) is engaged; The electric vehicle mode of the automobile is achieved by disconnecting the clutch unit (3) and the first and second dog clutches (23), stopping the operation of the internal combustion engine unit (1), and transmitting the rotational power generated in the motor-generator unit (2) to the transmission unit (4) and the differential unit (5); The real-time series mode of the automobile is such that the clutch unit (3) and the second dog clutch (23) are each disconnected, the drive shaft (25) of the first dog clutch (21) and the output shaft (11) of the internal combustion engine unit (1) are connected by the operation of the first dog clutch (21), and the internal combustion engine unit (1) is operated, so that the starter-generator unit (6) generates power by the internal combustion engine unit (1), and the rotational power generated in the motor-generator unit (2) is transmitted to the transmission unit (4) and the differential unit (5); In the driving stop mode and the coasting mode of the vehicle, each of the clutch unit (3) and the second dog clutch (23) is released, and the drive shaft (25) of the starter-generator unit (6) and the output shaft (11) of the internal combustion engine unit (1) are connected by the operation of the first dog clutch (21), so that the internal combustion engine unit (1) is operated, and the starter-generator unit (6) generates power by the internal combustion engine unit (1), and the motor-generator unit (2) rotates passively; The first parallel mode of the automobile is achieved in such a way that the first and second dog clutches (21, 23) are each disconnected, the clutch unit (3) is connected, and the rotational power generated in the internal combustion engine unit (1) is transmitted to the transmission unit (4) and the differential unit (5) via the passively rotating motor-generator unit (2); The second parallel mode of the automobile is achieved in such a way that the first and second dog clutches (21, 23) are each disconnected, the clutch unit (3) is connected, and the rotational power generated in each of the internal combustion engine unit (1) and the motor-generator unit (2) is transmitted to the transmission unit (4) and the differential unit (5); The third parallel mode of the automobile is achieved in such a way that the first and second dog clutches (21, 23) are each disconnected, the clutch unit (3) is connected, and the rotational power generated in the internal combustion engine unit (1) is transmitted to the transmission unit (4) and the differential unit (5) via the passively rotating motor-generator unit (2), while the motor-generator unit (2) generates power; The series-parallel mode of the automobile is such that the second dog clutch (23) is released, the first dog clutch (21) is operated to connect the drive shaft (25) of the starter-generator section (6) with the output shaft (11) of the internal combustion engine section (1), the starter-generator section (6) generates power, and the clutch section (3) is connected, so that the rotational power generated in each of the internal combustion engine section (1) and the motor-generator section (2) is transmitted to the transmission section (4) and the differential section (5); The first mode of regenerative power generation of the automobile is performed in a manner in which the motor-generator unit (6) generates power solely while the clutch unit (3) and the first and second dog clutches (21, 23) are released; A powertrain control method of a plug-in hybrid vehicle using a multi-functional starter generator, characterized in that the second regenerative power generation mode of the vehicle is performed in such a way that the starter-generator unit (6) and the motor-generator unit (6) each generate power while the clutch unit (3) is released and the second dog clutch (23) is operated so that the drive shaft (25) of the starter-generator unit (6) and the input shaft (13) of the motor-generator unit (2) are connected.

Images