CN112721905B

CN112721905B - Starting method and device of engine in dual-motor hybrid power system and vehicle

Info

Publication number: CN112721905B
Application number: CN202110018874.XA
Authority: CN
Inventors: 井俊超; 刘义强; 黄伟山; 左波涛; 杨俊�; 赵福成; 王瑞平; 肖逸阁; 安聪慧
Original assignee: Zhejiang Geely Holding Group Co Ltd; Ningbo Geely Royal Engine Components Co Ltd; Zhejiang Geely Power Train Co Ltd
Current assignee: Zhejiang Geely Holding Group Co Ltd; Ningbo Geely Royal Engine Components Co Ltd; Zhejiang Geely Power Train Co Ltd
Priority date: 2021-01-07
Filing date: 2021-01-07
Publication date: 2022-04-08
Anticipated expiration: 2041-01-07
Also published as: CN112721905A

Abstract

The invention provides a starting method and device of an engine in a dual-motor hybrid power system and a vehicle, and belongs to the technical field of vehicles. The dual-motor hybrid system includes an engine, a first motor connected to the engine, and a clutch connected between the first motor and a transmission system. The starting method comprises the following steps: acquiring current state data of a vehicle when an engine starting request is received; judging whether a pre-dragging torque application condition is met or not according to the current state data of the vehicle; if yes, generating a dragging starting signal, sending the dragging starting signal to a target component to be dragged for starting the engine, and controlling the target component to output a corresponding pre-dragging torque within a set time length from the moment the dragging starting signal is received, wherein the target component is the first motor or the clutch. The invention can effectively improve the smoothness of the engine starting by adopting the pre-dragging torque strategy.

Description

Starting method and device of engine in dual-motor hybrid power system and vehicle

Technical Field

The invention relates to the technical field of vehicles, in particular to a starting method and a starting device of an engine in a dual-motor hybrid power system and a hybrid power vehicle.

Background

With increasingly strict requirements on vehicle oil consumption and emission and development of electrified systems in various countries, the hybrid power technology becomes a key for realizing energy conservation and emission reduction of vehicles. Because the battery technology of the existing pure electric system is complex and the cost is high, the hybrid power system is widely popularized. The two-motor hybrid system is a high-efficiency hybrid system, and the general structure thereof is shown in fig. 1. The dual-motor hybrid system generally has three engine starting modes: a 12V starter motoring engine start (referred to as a 12V start), a P1 motor motoring engine start (referred to as a P1 motor start), and a clutch C0 motoring engine start (referred to as a clutch start). Normally, the two-motor hybrid system is started by using a P1 motor, and in the case of the fault of the P1 motor, the 12V starting or the clutch starting is selected according to the condition of the vehicle speed. However, in the prior art, during the startup of the P1 motor or the clutch startup, the drag torque of the P1 motor or the drag torque of the clutch C0 are both directly increased to a maximum, causing the drag torque to rise too fast, causing a shock and resulting in rough engine startup. Therefore, a starting method for improving the smoothness of engine starting in a dual-motor hybrid system is needed.

Disclosure of Invention

In view of the above, a starting method and apparatus for an engine in a two-motor hybrid system and a hybrid vehicle are proposed that overcome or at least partially address the above-mentioned problems.

An object of the present invention is to provide a starting method of an engine in a dual motor hybrid system, which can improve the smoothness of the engine start during the P1 motor start or clutch start.

A further object of the present invention is to prevent motor shudder during clutch launch, further improving launch smoothness.

In particular, according to an aspect of an embodiment of the present invention, there is provided a starting method of an engine in a dual motor hybrid system including an engine, a first motor connected to the engine, and a clutch connected between the first motor and a transmission system; the starting method comprises the following steps:

acquiring current state data of a vehicle when an engine starting request is received;

judging whether a pre-dragging torque application condition is met or not according to the current state data of the vehicle;

if yes, generating a dragging starting signal, sending the dragging starting signal to a target component to be dragged for starting the engine, and controlling the target component to output a corresponding pre-dragging torque within a set time length from the moment the dragging starting signal is received, wherein the target component is the first motor or the clutch.

Optionally, the current state data comprises engine speed and throttle state or driver requested torque;

the pre-drag torque application condition includes: the starting mode in which the engine speed is less than or equal to the preset speed threshold and the driver intends is a smooth starting mode.

Optionally, the throttle status comprises throttle opening and throttle rate of change;

the step of judging whether the pre-dragging torque applying condition is satisfied according to the current state data of the vehicle includes:

judging whether the acquired engine rotating speed is less than or equal to the preset rotating speed threshold value or not; and is

And judging whether the starting mode intended by the driver is a smooth starting mode or not according to the acquired accelerator opening and accelerator change rate or the acquired driver request torque.

Optionally, the step of determining whether the start mode intended by the driver is the smooth start mode according to the acquired accelerator opening and accelerator change rate or the acquired driver request torque comprises:

judging whether the accelerator opening is larger than a first accelerator opening threshold value and the accelerator change rate is larger than a preset change rate threshold value, and if not, determining that the starting mode intended by the driver is a stable starting mode; or,

and judging whether the torque requested by the driver is smaller than or equal to a first wheel end torque threshold value, if so, determining that the starting mode intended by the driver is a smooth starting mode.

Optionally, the preset rotation speed threshold is 50 rpm;

the first accelerator opening threshold value is 70%;

the preset change rate threshold value is 300%/s;

the current state data further includes a current vehicle speed of the vehicle, the first wheel end torque threshold being determined by the current vehicle speed of the vehicle.

Optionally, the set time period is 0.2-0.4 s;

the pre-dragging torque corresponding to the first motor is 15-30 N.m;

the pre-drag torque corresponding to the clutch is 2-4N · m.

Optionally, the dual-motor hybrid system further comprises a second motor connected with the speed change system and used for driving wheels;

the starting method further comprises the following steps:

and in the case that the target component is the clutch, performing active damping control on the second motor during the process that the clutch drags the engine to start.

Optionally, the step of actively damping controlling the second electric machine comprises:

acquiring a request rotating speed of a driver and an actual rotating speed of the second motor;

calculating a difference between the requested rotational speed and the actual rotational speed;

and carrying out proportional integral control on the second motor according to the difference value so as to compensate the output torque of the second motor.

According to another aspect of the embodiments of the present invention, there is also provided a starting apparatus of an engine in a dual-motor hybrid system, including a memory and a processor, wherein the memory stores a control program, and the control program is used for implementing the starting method of any one of the preceding paragraphs when executed by the processor.

According to another aspect of the embodiment of the invention, a hybrid vehicle is further provided, which comprises a dual-motor hybrid system and the starting device of the engine in the dual-motor hybrid system.

In the method and the device for starting the engine in the dual-motor hybrid power system, which are provided by the embodiment of the invention, the target component (the first motor, namely the P1 motor or the clutch) can be controlled to output the corresponding pre-dragging torque within the set time length from the moment when the dragging starting signal is received under the condition that the applying condition of the pre-dragging torque is met, so that the target component can drag the engine to a certain rotating speed with the pre-dragging torque before the dragging torque of the target component is increased to the maximum to drag the engine to reach the target rotating speed. Therefore, the dragging torque of the target component cannot be directly increased to the maximum, but reaches an intermediate value (namely the value of the pre-dragging torque) and then reaches the maximum, so that the impact caused by the fact that the dragging torque is increased too fast in the starting process can be avoided, and the smoothness of the starting of the engine is effectively improved.

Further, whether the pre-dragging torque applying condition is met or not is accurately judged according to the rotating speed of the engine and the state of the accelerator or the torque requested by the driver, and the effectiveness of the pre-dragging torque on improving the smoothness in the starting process of the engine can be ensured.

Further, in the process that the clutch drags the engine to start (namely, the clutch starts), the second motor (namely, the driving motor) is subjected to active damping control, so that the second motor can be prevented from shaking in the clutch starting process, and the starting smoothness is further improved.

The foregoing description is only an overview of the technical solutions of the present invention, and the embodiments of the present invention are described below in order to make the technical means of the present invention more clearly understood and to make the above and other objects, features, and advantages of the present invention more clearly understandable.

The above and other objects, advantages and features of the present invention will become more apparent to those skilled in the art from the following detailed description of specific embodiments thereof, taken in conjunction with the accompanying drawings.

Drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to refer to like parts throughout the drawings. In the drawings:

FIG. 1 is a schematic diagram of a dual motor hybrid system;

FIG. 2 is a schematic illustration of the dual motor hybrid system shown in FIG. 1 at clutch start-up;

FIG. 3 is a flowchart illustrating a method for starting an engine in a dual-motor hybrid system according to a first embodiment of the present invention;

fig. 4 is a schematic diagram of a starting effect of the starting method of the engine in the dual-motor hybrid power system according to the first embodiment of the present invention after the P1 motor is started and the pre-dragging torque is applied;

FIG. 5 is a schematic diagram illustrating a starting effect of a P1 motor in the prior art when a pre-dragging torque is not applied during starting;

FIG. 6 is a flowchart illustrating a method for starting an engine in a dual-motor hybrid system according to a second embodiment of the present invention;

FIG. 7 is a schematic diagram illustrating various stages in the starting process of the P1 motor according to a second embodiment of the present invention;

FIG. 8 is a flowchart illustrating a method for starting an engine in a dual-motor hybrid system according to a third embodiment of the present invention;

fig. 9 is a schematic structural diagram of a starting apparatus of an engine in a dual motor hybrid system according to an embodiment of the present invention.

Detailed Description

Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

The dual-motor hybrid power system is a key technology for realizing energy conservation and emission reduction of vehicles at present. As shown in fig. 1, the two-motor hybrid system may generally include an engine 1, a first motor 2 (identified as P1 in fig. 1) connected to the engine 1, and a clutch 3 (identified as C0 in fig. 1) connected between the first motor 2 and a transmission system 5. The transmission system 5 is connected to wheels 6. The dual motor hybrid system may further include a battery 4 connected to the first motor 2. Still further, the two-motor hybrid system may further include a second motor 7 (identified as P2 in fig. 1), the second motor 7 being connected to the transmission system 5 and to both the battery 4 and the clutch 3.

Dual motor hybrid systems generally have three modes: an electric only mode, a series mode, and a parallel mode. In the series mode, the clutch C0 is disengaged, the engine 1 charges the battery 4 via the first electric machine 2 (i.e., the P1 electric machine), and the battery 4 supplies electric power to the second electric machine 7 (i.e., the P2 electric machine) so that the P2 electric machine drives the wheels 6. In parallel mode, clutch C0 is engaged and the engine 1 and the P2 electric machine are simultaneously driving the wheels 6 directly.

As described above, a dual-motor hybrid system generally has three engine starting modes: the 12V starter cranking the engine 1 (abbreviated as 12V cranking, the 12V starter is not shown in fig. 1), the P1 motor cranking the engine 1 (abbreviated as P1 motor cranking), and the clutch C0 cranking the engine 1 (abbreviated as clutch cranking). Normally, the two-motor hybrid power system is started by adopting a P1 motor, and in the case of the fault of the P1 motor, the 12V starting or the clutch starting is selected according to the current vehicle speed. At clutch start, as shown in fig. 2, the clutch C0 is engaged, dragging the engine 1 through the clutch C0 to start, and the black arrow in fig. 2 indicates the transmission direction of the dragging torque.

However, in the prior art, during the starting process of the P1 motor or the starting process of the clutch, the dragging torque of the P1 motor or the dragging torque of the clutch C0 directly rises to the maximum, so that the dragging torque rises too fast, and a shock is caused, thereby causing unsmooth starting of the engine.

To solve or at least partially solve the technical problem, an embodiment of the present invention provides a starting method for an engine in a dual-motor hybrid system. The technical solutions in the embodiments of the present invention will be clearly and completely described below through the first to fourth embodiments of the present invention.

Example one

The structure of the two-motor hybrid system in this embodiment is shown in fig. 1, and includes an engine 1, a first motor 2 (i.e., a P1 motor) connected to the engine 1, and a clutch 3 (i.e., a clutch C0) connected between the first motor 2 and a transmission system 5.

Referring to fig. 3, the method for starting the engine in the dual motor hybrid system of the present embodiment may include at least the following steps S302 to S306.

In step S302, current state data of the vehicle is acquired upon receipt of an engine start request.

And step S304, judging whether the pre-dragging torque applying condition is met according to the current state data of the vehicle. If yes, go to step S306.

Step S306, generating a dragging start signal to send to a target component for starting the engine 1 to be dragged, and controlling the target component to output a corresponding pre-dragging (Prefill) torque within a set time period since the dragging start signal is received, wherein the target component is the first motor 2 (i.e., the P1 motor) or the clutch 3 (i.e., the clutch C0).

In the method for starting the engine in the dual-motor hybrid power system provided by the embodiment of the invention, the target component (the P1 motor or the clutch C0) can be controlled to output the corresponding pre-dragging torque within the set time length from the reception of the dragging start signal under the condition that the condition of applying the pre-dragging torque is met, so that the target component can drag the engine 1 to a certain rotating speed with the pre-dragging torque before the dragging torque of the target component is increased to the maximum to drag the engine 1 to reach the target rotating speed. Therefore, the dragging torque of the target component cannot be directly increased to the maximum, but reaches an intermediate value (namely the value of the pre-dragging torque) and then reaches the maximum, so that the impact caused by the fact that the dragging torque is increased too fast in the starting process can be avoided, and the smoothness of the starting of the engine is effectively improved.

Of course, in practical applications, when an engine start request is received, the current state of the P1 motor, or the current state of the P1 motor and the current vehicle speed of the vehicle may be obtained first, so as to determine whether the target component to be used to start the engine 1 is the P1 motor or the clutch C0. And if the target component is the P1 motor or the clutch C0, acquiring the current state data of the vehicle, and judging whether the pre-dragging torque application condition is met according to the current state data of the vehicle. Specifically, if the current state of the P1 motor is normal, it may be determined that the target component is the P1 motor. If the current state of the P1 motor is a fault and the current vehicle speed is greater than a preset vehicle speed threshold (e.g., 10km/h), it can be determined that the target component is clutch C0. Of course, the current vehicle speed of the vehicle may be one of the current state data of the vehicle, and the required current state data of the vehicle is acquired when the engine start request is received.

In the above step S302, the current state data of the vehicle may include the engine 1 rotation speed and the throttle state or the driver requested torque. Accordingly, the pre-towing torque application condition mentioned in step S304 may include: the rotating speed of the engine 1 is less than or equal to a preset rotating speed threshold value, and the starting mode intended by the driver is a smooth starting mode, wherein the starting mode intended by the driver can be judged according to the accelerator state or the torque requested by the driver. The preset rotating speed threshold value can be set according to the actual parameters of the engine 1, and when the rotating speed of the engine 1 is greater than the preset rotating speed threshold value, the pre-dragging torque cannot drag the engine 1. Specifically, the preset rotation speed threshold may be set to 50rpm, for example.

When it is determined in step S304 that the pre-dragging torque application condition is satisfied, it may be considered that the pre-dragging torque policy is enabled, and step S306 is performed.

In a particular embodiment, the throttle status may include throttle opening and throttle rate of change. In this case, step S304 may be embodied as: judging whether the acquired rotating speed of the engine 1 is less than or equal to a preset rotating speed threshold value; and judging whether the starting mode intended by the driver is a smooth starting mode or not according to the acquired accelerator opening and accelerator change rate or the acquired driver request torque. If the rotation speed of the engine 1 is less than or equal to the preset rotation speed threshold and the start mode intended by the driver is the smooth start mode, step S306 is executed.

Further, the step of judging whether the start mode intended by the driver is the smooth start mode or not based on the acquired accelerator opening and accelerator change rate or the acquired driver requested torque includes:

judging whether the accelerator opening is larger than a first accelerator opening threshold value or not and the accelerator change rate is larger than a preset change rate threshold value or not, and if not (namely the accelerator opening is smaller than or equal to the first accelerator opening threshold value or the accelerator change rate is smaller than or equal to the preset change rate threshold value), determining that the starting mode intended by the driver is a stable starting mode; or,

In the present embodiment, the first accelerator opening degree threshold and the preset rate of change threshold may be set to 70% and 300%/s, respectively. The first wheel end torque threshold is related to the current vehicle speed of the vehicle, so that the current vehicle speed of the vehicle may also be used as one item of the current state data of the vehicle, and the first wheel end torque threshold is determined according to the current vehicle speed of the vehicle in step S302. Specifically, the wheel-end torque limit value corresponding to the current vehicle speed of the vehicle may be obtained as the first wheel-end torque threshold value by looking up a relationship table between the vehicle speed and the wheel-end torque limit value according to the current vehicle speed of the vehicle. Table 1 below illustrates an exemplary vehicle speed versus wheel-end torque limit.

TABLE 1 relationship of vehicle speed and wheel-end Torque Limit

Vehicle speed (km/h)	3	10	20	30	50	100
							Wheel end torque limit (N m)	1500	600	235	200	150	100

In looking up the table, the wheel-end torque limit value corresponding to the current vehicle speed of the vehicle between each vehicle speed point in the relationship table of vehicle speed and wheel-end torque limit value can be calculated by interpolation.

In the embodiment, whether the pre-dragging torque applying condition is met or not is accurately judged according to the rotating speed and the accelerator state of the engine 1 or the torque requested by the driver, so that the effectiveness of the pre-dragging torque on improving the smoothness in the starting process of the engine 1 can be ensured.

In the above step S306, the set time period may be in the range of 0.2 to 0.4S. The pre-dragging torques corresponding to different target components can be set according to the real vehicle calibration result when the vehicle is started. When the target component is the P1 motor, the pre-drag torque may be set to a value that is too large to cause a shock, and too small to provide a damping effect, and therefore, the pre-drag torque corresponding to the P1 motor may preferably be set to 15 to 30N · m. When the target component is clutch C0, the corresponding pre-drag torque setting should ensure that clutch C0 is fully engaged, and therefore may preferably be set to 2-4N m.

After the pre-dragging torque is applied, the dragging torque of the target component is increased to the maximum value again to drag the engine 1 to reach the target rotating speed, so that the engine 1 is started, the dragging torque of the target component is prevented from being directly increased to the maximum value, and the smoothness is improved. The following description will take the P1 motor start as an example. Fig. 4 shows a starting effect after the P1 motor is started by using the pre-dragging torque in the starting method of the present embodiment, and fig. 5 shows a starting effect in a case where the P1 motor is not started by using the pre-dragging torque in the prior art. Referring to fig. 4, the P1 motor outputs the pre-traction torque at the time point (time point set to 0 s) when the P1 motor receives the traction start signal, the pre-traction torque reaches 20N · m at 0.1s, and is maintained at 20N · m at 0.1s to 0.2s, so that the traction engine 1 reaches a certain rotation speed. After 0.2s, the pre-motoring torque is gradually unloaded, and drops to 0 at 0.4 s. Meanwhile, after 0.2s, the P1 motor output drag torque is increased to a maximum value to drag the engine 1 to a target rotation speed, and after the engine 1 reaches the target rotation speed, the P1 motor drag torque is unloaded. In contrast, the P1 motor in fig. 5 has no pre-drag torque after receiving the drag start signal, and the drag torque is directly increased to the maximum value. Comparing fig. 4 and 5, the fluctuation range of the acceleration of the vehicle during the starting process of fig. 4 is 0.16m/s²Whereas the fluctuation range of the acceleration of the vehicle during the starting process of fig. 5 reaches 0.23m/s²Compared with the fluctuation range of the acceleration in FIG. 4, the fluctuation range of the acceleration is larger by 0.07m/s²Therefore, it can be seen that, with the starting method of the present embodiment, the shock in starting the engine 1 can be significantly reduced, and the starting smoothness can be improved.

Further, as shown in fig. 1, the two-motor hybrid system of the present embodiment may further include a second motor 7 (i.e., a P2 motor) connected to the transmission system 5 for driving the wheels 6. Since the second motor 7 drives the wheel 6, the second motor 7 may also be referred to as a drive motor. Since the second electric machine 7 needs to compensate for the loss of clutch start in addition to driving the wheels 6 during the clutch start, the second electric machine 7 may shake, which may affect the starting smoothness. In order to prevent the judder of the second motor 7 during the clutch start, the starting method of the engine in the dual-motor hybrid system of the embodiment may further include the steps of: in the case where the target component is the clutch C0, the active damping control is performed on the second electric machine 7 during the process in which the clutch C0 drags the engine 1 for starting.

Specifically, the step of performing active damping control on the second motor 7 may include:

acquiring a requested rotation speed of a driver and an actual rotation speed of the second motor 7;

Proportional-Integral (PI) control is performed on the second motor 7 according to the difference to compensate for the output torque of the second motor 7.

Proportional integral control is a common control strategy and will not be described in detail herein.

In the embodiment, the active damping control is performed on the second motor 7 in the clutch starting process, so that the second motor 7 can be prevented from shaking in the clutch starting process, and the starting smoothness is further improved.

Example two

The difference between this embodiment and the first embodiment is: in the process that the target component (the first motor 2 or the clutch 3) drags the engine 1 to start, the target component is controlled to output corresponding pre-dragging torque within a set time length since the dragging start signal is received, and the fuel injection time of the engine 1 is controlled in a targeted mode according to the temperature of coolant of the engine 1 and the intention of a driver, so that starting impact, starting failure or engine speed drop caused by too early or too late fuel injection of the engine 1 are prevented, and the starting smoothness and safety of the engine 1 are improved.

Referring to fig. 6, the method for starting the engine in the dual motor hybrid system of the present embodiment may include at least the following steps S602 to S612.

In step S602, when an engine start request is received, current state data of the vehicle is acquired, where the current state data of the vehicle includes the rotation speed of the engine 1, the coolant temperature of the engine 1 (typically, the coolant temperature of the engine 1), and the throttle state or the driver requested torque.

In step S604, the start mode intended by the driver is determined based on the current state data of the vehicle.

In step S606, it is judged whether or not the pre-traction torque application condition is satisfied according to the rotation speed of the engine 1 and the start mode intended by the driver. If yes, go to step S608.

In step S608, a drag start signal is generated and sent to a target component for starting the engine 1 to be dragged, and the target component is controlled to output a corresponding pre-drag torque for a set time period since the drag start signal is received, wherein the target component is the first motor 2 (i.e., the P1 motor) or the clutch 3 (i.e., the clutch C0).

In step S610, the fuel injection time of the engine 1 corresponding to the target component is determined according to the coolant temperature of the engine 1 and the start mode intended by the driver.

And step S612, controlling the engine 1 to inject oil at the determined oil injection time in the process that the target component drags the engine 1 to start.

In this embodiment, the start mode intended by the driver may include a quick start mode and a smooth start mode. The throttle state may include throttle opening and throttle rate of change.

Specifically, step S604 may be implemented as: judging whether the accelerator opening is larger than a first accelerator opening threshold value and the accelerator change rate is larger than a preset change rate threshold value; if so, determining that the starting mode intended by the driver is a quick starting mode; if not (namely the accelerator opening is smaller than or equal to the first accelerator opening threshold value, or the accelerator change rate is smaller than or equal to the preset change rate threshold value), determining that the starting mode intended by the driver is a smooth starting mode. Or, judging whether the driver request torque is larger than a first wheel end torque threshold value; if so, determining that the starting mode intended by the driver is a quick starting mode; if not, determining that the starting mode intended by the driver is a smooth starting mode.

The pre-towing torque application condition in step S606 is as described in embodiment one, and is not repeated here. Specifically, if the rotation speed of the engine 1 is less than or equal to the preset rotation speed threshold value and the start mode intended by the driver is the smooth start mode, it is determined that the pre-dragging torque application condition is satisfied.

The execution manner of step S608 is as described in one embodiment, and is not repeated here.

In a specific embodiment, the above step S610 can be implemented as follows:

when the starting mode intended by the driver is a quick starting mode, determining the fuel injection time of the engine 1 as the time when the rotating speed of the engine 1 is greater than 0;

when the starting mode intended by the driver is a smooth starting mode and the temperature of the coolant of the engine 1 is greater than the preset heat engine starting temperature, determining the fuel injection time of the engine 1 as the time for completely unloading the dragging torque of the target component;

when the starting mode intended by the driver is a smooth starting mode and the coolant temperature of the engine 1 is less than or equal to the preset heat engine starting temperature, searching a corresponding relation table of the coolant temperature of the engine and the torque limit value of the target component to obtain the target torque limit value of the target component corresponding to the coolant temperature of the engine 1, and determining the fuel injection time of the engine 1 as the time when the dragging torque of the target component is less than the target torque limit value.

Further, the map includes a first map of the engine coolant temperature and the torque limit of the first electric machine 2 (i.e., the P1 electric machine) and a second map of the engine coolant temperature and the torque limit of the clutch 3 (i.e., the clutch C0). In the first map, the coolant temperature of the engine is inversely proportional to the torque limit value of the first electric machine 2. In the second map, the coolant temperature of the engine is inversely proportional to the torque limit value of the clutch 3. The coolant temperature and the corresponding torque limit value of the engine in the correspondence table are calibrated according to the actual vehicle performance, and the torque limit value corresponding to each temperature is a critical value which can cause starting failure or engine speed drop when the dragging torque of the target component reaches the limit value and no oil injection is performed when the coolant temperature of the engine is below the preset heat engine starting temperature. The preset heat engine starting temperature may be set according to the nature parameters of the engine in practical use, and may be generally set to 60 ℃.

Tables 2 and 3 below exemplarily show a first table of correspondence of engine coolant temperature to torque limit of the P1 motor and a second table of correspondence of engine coolant temperature to torque limit of clutch C0.

TABLE 2 first correspondence table of coolant temperature of engine and torque limit of P1 motor

Temperature (. degree.C.) of engine coolant	-5	10	25	35	45	60
							Torque limit (N m)	75	65	55	50	45	10

TABLE 3 second Table of correspondence of engine coolant temperature and Torque Limit for Clutch C0

Temperature (. degree.C.) of engine coolant	-5	10	25	35	45	60
							Torque limit (N m)	75	65	55	50	45	-3

In one practical application, the coolant temperature and the torque limit value in the first and second corresponding relationship tables are in a one-to-one linear relationship, and when the tables are looked up, the engine coolant temperature falling between the temperature points in table 2 or table 3 can be calculated by interpolation to obtain the torque limit value corresponding to the engine coolant temperature. In another practical application, the coolant temperature ranges in the first and second correspondence tables correspond to torque limits, for example, a temperature range less than or equal to-5 ℃ corresponds to a torque limit of 75N · m, a temperature range greater than-5 ℃ and less than or equal to 10 ℃ corresponds to a torque limit of 65N · m, and so on. When the table is looked up, the torque limit value corresponding to the engine coolant temperature is determined according to the temperature interval where the engine coolant temperature is located.

Further, in one embodiment, after determining the injection time of the engine 1 in different situations, the above step S612 may be performed in different situations. Specifically, when the starting mode intended by the driver is the quick starting mode, the current rotating speed of the engine 1 is acquired in real time in the process that the target component drags the engine 1 to start; and when the current rotating speed of the engine 1 is greater than 0, controlling the engine 1 to inject fuel. When the starting mode intended by the driver is a stable starting mode, acquiring the dragging torque of the target component in real time in the process of dragging the engine 1 to start the target component; under the condition that the temperature of the coolant of the engine 1 is higher than the preset heat engine starting temperature, when the dragging torque of the target component is completely unloaded, controlling the engine 1 to inject oil; in the case where the coolant temperature of the engine 1 is less than or equal to the preset heat engine starting temperature, the engine 1 is controlled to inject fuel when the drag torque of the target component is less than the target torque limit value. In this embodiment, the standard for completely unloading the drag torque of the target component may be set according to the actual application requirement. In general, when the drag torque of the target component is less than the preset torque lower limit value, it may be considered that the drag torque of the target component has been completely unloaded. In one example, the preset lower torque limit of the P1 motor may be set to 10N · m, that is, the P1 motor drag torque may be considered to be completely unloaded when the P1 motor drag torque is less than 10N · m. The preset lower torque limit value for clutch C0 may be set to-3N m, that is, the drag torque of clutch C0 may be considered to be completely unloaded when the drag torque of clutch C0 is less than-3N m.

In the present embodiment, the fuel injection timing of the engine 1 is controlled in a targeted manner in accordance with the coolant temperature of the engine 1 and the start mode intended by the driver, in addition to the pre-traction torque strategy. For the quick start mode, the injection time of the engine 1 is a time when the rotation speed of the engine 1 is greater than 0, that is, the engine 1 does not delay the injection of fuel, thereby ensuring the response speed of the quick start. For the steady start mode and the condition that the coolant temperature of the engine 1 is greater than the preset heat engine start temperature (i.e. the heat engine start), the fuel injection time of the engine 1 is the time for completely unloading the dragging torque of the first electric machine 2 or the clutch 3, that is, the engine 1 delays to completely unload the dragging torque and injects fuel (not defined as delayed fuel injection), which can avoid disturbance impact caused by incomplete unloading of the torque of the first electric machine 2 or the clutch 3, and improve the start smoothness. For the steady start mode and the coolant temperature of the engine 1 is less than or equal to the preset thermal engine start temperature (i.e. cold start), the fuel injection time of the engine 1 is the time when the dragging torque of the first electric machine 2 or the clutch 3 is less than the target torque limit value, and at this time, the fuel injection can be started (not defined as advanced fuel injection) when the dragging torque of the first electric machine 2 or the clutch 3 is less than the corresponding target torque limit value instead of waiting for the dragging torque to completely unload the fuel injection, so that the rotating speed of the engine 1 is prevented from dropping or the starting failure is prevented.

Of course, those skilled in the art will recognize that step S612 is executed during the start of the target component (P1 motor or clutch C0) dragging the engine 1, especially during the smooth start mode, regardless of whether the engine 1 is controlled to inject fuel late or early, during the unloading of the dragging torque after the target component drags the engine 1 to reach the target speed. Thus, the process of the P1 motor or the clutch C0 dragging the engine 1 to start can be divided into the following four phases: (1) a pre-dragging stage, in which the P1 motor or the clutch C0 outputs pre-dragging torque to drag the engine 1 to reach a certain rotating speed; (2) a motoring phase, in which the P1 electric machine or the clutch C0 motoring the engine 1 to the target speed; (3) a torque unloading stage, wherein the dragging torque of the P1 motor or the clutch C0 is unloaded to be about a preset lower torque limit value; (4) and an engine injection phase, in which the engine 1 starts injecting fuel. Fig. 7 exemplarily shows the above four stages in the starting process of the P1 motor in the second embodiment.

It should be noted that step S610 may be executed after step S604 and before step S612, but is not necessarily executed after step S608.

EXAMPLE III

The difference between this embodiment and the first embodiment is: before the engine 1 is started by adopting the pre-dragging torque strategy, whether a waiting clutch starting strategy can be started or not is judged, so that the 12V starting is not carried out even if the P1 motor has a fault and the vehicle speed is less than or equal to the preset vehicle speed threshold value and the engine starting request is carried out, and the clutch is started when the vehicle speed is increased to be greater than the preset vehicle speed threshold value and the vehicle speed condition of the clutch starting is met.

Referring to fig. 8, the method for starting the engine in the dual motor hybrid system of the present embodiment may include at least the following steps S802 to S814.

In step S802, when the engine start request is received, the current state of the first electric machine 2 is acquired.

Step S804, if the current state of the first motor 2 is a fault, obtaining current state data of the vehicle, where the current state data of the vehicle at least includes the current speed of the vehicle and the rotation speed of the engine 1.

Step S806, judging whether the current speed of the vehicle is less than or equal to the preset speed threshold value and whether other current state data of the vehicle meet the starting condition of the waiting clutch. If yes, that is, the current vehicle speed of the vehicle is less than or equal to the preset vehicle speed threshold value, and the other current state data of the vehicle meet the waiting clutch activation condition, step S808 is executed.

And step S808, monitoring the speed of the vehicle in real time.

Step S810, determining a start mode intended by the driver according to the current state data of the vehicle.

In step S812, it is determined whether the pre-traction torque application condition is satisfied according to the rotation speed of the engine 1 and the start mode intended by the driver. If yes, go to step S814.

Step S814, when the vehicle speed of the vehicle is greater than the preset vehicle speed threshold, generating a dragging start signal to be sent to the clutch 3, so as to control the clutch 3 to drag the engine 1 to start, and control the clutch 3 to output the corresponding pre-dragging torque within a set time period since the dragging start signal is received.

The wait for clutch activation condition in step S806 may include a condition that there is acceleration of the vehicle and a condition that the vehicle does not need the engine to be running all the time. When the condition that the vehicle accelerates is met, the vehicle can be guaranteed to reach the vehicle speed required by starting of the clutch in a short time, and the situation that the normal operation of the vehicle cannot be guaranteed due to the fact that waiting time is too long is avoided. When the condition that the vehicle does not need the engine to operate all the time is met, the rationality of the waiting clutch starting strategy can be ensured, and the normal operation of the vehicle is ensured.

Specifically, the current state data of the vehicle may further include an acceleration or an accelerator opening degree (may also be referred to as an accelerator opening degree) and a driving mode of the vehicle. Accordingly, the condition that the vehicle has an acceleration request includes: the acceleration is positive (i.e., the vehicle has a positive acceleration) and greater than a preset acceleration threshold, or the accelerator opening is greater than a second accelerator opening threshold (indicating that the accelerator pedal is active). The preset acceleration threshold and the second accelerator opening threshold may be set according to actual application requirements, for example, the preset acceleration threshold may be set to 0.4m/s²The second accelerator opening threshold may be set to 5%. Conditions under which the vehicle does not require the engine to operate at all times include: the driving mode of the vehicle is not equal to the sport mode. Hybrid vehicles may typically have multiple drive modes, such as an energy savings mode, a normal mode, a sport mode, etc., where the engine is required to run all the time to ensure the high power requirements of the sport mode, and therefore, a waiting clutch launch strategy may not be enabled in the sport mode.

Further, the current state data of the vehicle may also include a driver requested torque. The driver requested torque refers to a driver requested wheel torque. Accordingly, the wait for clutch activation condition may further include: the driver requested torque is less than the second wheel end torque threshold. The second wheel end torque threshold may be set according to actual application requirements, and may be set to 1000N · m, for example. When the torque requested by the driver is low, the starting response speed required by the user is low, and the waiting clutch starting strategy is started under the condition, so that the accelerated driving experience of the user is not influenced as much as possible while the NVH performance and the stability are improved.

In one embodiment, the current state data of the vehicle may also include throttle state (specifically throttle opening and throttle rate of change) or driver requested torque. In this case, the step of determining the activation mode intended by the driver based on the current state data of the vehicle is not repeated as described above.

The execution of step S812 is also as described above and is not repeated.

In step S814, when the vehicle speed of the vehicle is monitored to be greater than the preset vehicle speed threshold (i.e., the vehicle speed satisfies the vehicle speed condition for starting the clutch), a dragging start signal is generated and sent to the clutch 3. The clutch 3 drags the engine 1 to start in response to the drag start signal, and outputs a corresponding pre-drag torque for a set time period since the drag start signal is received, preventing the drag torque of the clutch 3 from being directly increased to a maximum value.

The execution sequence between steps S810 and S812 and step S808 is not fixed, and steps S810 and S812 may be performed simultaneously with step S808 or before step S808.

Of course, if the current state of the first motor 2 obtained in step S802 is normal and it is determined that the first motor 2 is used as the target component for starting the engine 1 to be dragged, the subsequent steps are the same as those in the case where the target component is the first motor 2 in the first embodiment, and are not described again here.

In the embodiment, by defining the waiting clutch starting strategy after the P1 motor fails, even if the engine starting request is generated when the P1 motor fails and the vehicle speed is less than or equal to the preset vehicle speed threshold, 12V starting is not performed, and the clutch is started when the vehicle speed is increased to be greater than the preset vehicle speed threshold and the vehicle speed condition of the clutch starting is met, so that noise and oscillation generated during 12V starting are avoided, and the NVH performance and the stability of engine starting are improved.

Example four

The difference between this embodiment and the second embodiment is: before starting the engine 1 using the pre-motoring torque strategy, it is determined whether a waiting clutch start strategy can be activated. Specifically, the starting method of the engine in the dual-motor hybrid system of the embodiment may at least include the following steps:

(1) upon receipt of the engine start request, the current state of the first electric machine 2 is acquired. If the current state of the first motor 2 is a fault, executing (2), and if the current state of the first motor 2 is normal, executing (11).

(2) Current state data of the vehicle is acquired, and the current state data of the vehicle at least includes a current vehicle speed of the vehicle, a rotational speed of the engine 1, and a coolant temperature of the engine 1. Then (3) is performed.

(3) And judging whether the current vehicle speed of the vehicle is less than or equal to a preset vehicle speed threshold value or not and whether other current state data of the vehicle meet the starting condition of the waiting clutch or not. And if so, namely the current vehicle speed of the vehicle is less than or equal to the preset vehicle speed threshold value and other current state data of the vehicle meet the starting condition of the waiting clutch, executing (4).

(4) And monitoring the speed of the vehicle in real time. Then (5) is performed.

(5) And judging the starting mode of the intention of the driver according to the current state data of the vehicle. Then (6) is executed.

The steps for determining the activation mode intended by the driver are as described above.

(6) It is judged whether or not the pre-motoring torque application condition is satisfied according to the rotation speed of the engine 1 and the start mode of the driver's intention. If yes, executing (7), otherwise executing (8).

The step of determining whether the pre-drag torque application condition is satisfied is as described above.

(7) When the vehicle speed of the vehicle is greater than the preset vehicle speed threshold value, a first dragging start signal is generated and sent to the clutch 3, so that the clutch 3 is controlled to drag the engine 1 to start, and the clutch 3 is controlled to output corresponding pre-dragging torque within a set time length from the time when the first dragging start signal is received. Then (9) is executed.

(8) When the vehicle speed of the vehicle is greater than the preset vehicle speed threshold value, a second dragging start signal is generated and sent to the clutch 3, so that the clutch 3 is controlled to drag the engine 1 to start. Thereafter, the process proceeds to (9).

In this step, the clutch is started in the conventional non-pre-motoring torque manner when the pre-motoring torque application condition is not satisfied.

(9) The fuel injection time of the engine 1 corresponding to the clutch 3 is determined according to the coolant temperature of the engine 1 and the start pattern intended by the driver. Then (10) is executed.

(10) And controlling the engine 1 to inject fuel at the determined fuel injection time during the process that the clutch 3 drags the engine 1 to start, thereby completing the starting of the engine 1.

(11) Current state data of the vehicle is acquired, the current state data of the vehicle including at least the rotation speed of the engine 1 of the vehicle and the coolant temperature of the engine 1. Then (12) is executed.

(12) And judging the starting mode of the intention of the driver according to the current state data of the vehicle. Then (13) is executed.

(13) It is judged whether or not the pre-motoring torque application condition is satisfied according to the rotation speed of the engine 1 and the start mode of the driver's intention. If yes, executing (14), otherwise executing (15).

(14) And generating a third dragging start signal, sending the third dragging start signal to the first motor 2 to control the first motor 2 to drag the engine 1 to start, and controlling the first motor 2 to output a corresponding pre-dragging torque within a set time length from the receiving of the third dragging start signal. Then (16) is executed.

(15) And generating a fourth dragging start signal to be sent to the first motor 2 so as to control the first motor 2 to drag the engine 1 to start. Thereafter, next (16) is performed.

(16) The fuel injection time of the engine 1 corresponding to the first electric machine 2 is determined according to the coolant temperature of the engine 1 and the start pattern intended by the driver. Then (17) is executed.

(17) And controlling the engine 1 to inject fuel at the determined fuel injection time during the process that the first motor 2 drives the engine 1 to start, thereby completing the starting of the engine 1.

The embodiment defines a waiting clutch starting strategy after the P1 motor fails, and combines a pre-dragging torque strategy and an oil injection strategy in the P1 motor starting or clutch starting, so that the smoothness and the safety of the starting of the engine 1 can be effectively improved.

Based on the same technical concept, the embodiment of the invention also provides a starting device 100 of the engine in the dual-motor hybrid power system. As shown in fig. 9, the starting apparatus 100 includes a memory 110 and a processor 120. The memory 110 stores a control program, and the control program is executed by the processor 120 to implement the engine starting method in the dual-motor hybrid system according to any of the foregoing embodiments or the combination of the foregoing embodiments.

The starting device of the embodiment can enable the target component to drag the engine to a certain rotating speed with the pre-dragging torque before the dragging torque of the target component is increased to the maximum to drag the engine to the target rotating speed, so that the dragging torque of the target component cannot directly rise to the maximum, but reaches an intermediate value (namely the value of the pre-dragging torque) and then reaches the maximum, and thus, the impact caused by the fact that the dragging torque rises too fast in the starting process can be avoided, and the smoothness of starting the engine is effectively improved.

Based on the same technical concept, the embodiment of the invention also provides a hybrid vehicle, which comprises a dual-motor hybrid system and the starting device 100 of the engine in the dual-motor hybrid system described in the foregoing embodiment. A two-motor hybrid system may be described with reference to fig. 1.

According to any one or a combination of multiple optional embodiments, the embodiment of the present invention can achieve the following advantages:

in the method and the device for starting the engine in the dual-motor hybrid power system, which are provided by the embodiment of the invention, the target component (the first motor 2, namely the P1 motor, or the clutch 3) can be controlled to output the corresponding pre-dragging torque within the set time length from the moment when the dragging starting signal is received under the condition that the applying condition of the pre-dragging torque is met, so that the target component can drag the engine to a certain rotating speed with the pre-dragging torque before the dragging torque of the target component is increased to the maximum to drag the engine to reach the target rotating speed. Therefore, the dragging torque of the target component cannot be directly increased to the maximum, but reaches an intermediate value (namely the value of the pre-dragging torque) and then reaches the maximum, so that the impact caused by the fact that the dragging torque is increased too fast in the starting process can be avoided, and the smoothness of the starting of the engine is effectively improved.

Further, in the process that the clutch drags the engine to start (namely, the clutch starts), through carrying out active damping control on the second motor 7 (namely, the driving motor), the shake of the second motor 7 in the clutch starting process can be prevented, and the starting smoothness is further improved.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments can be modified or some or all of the technical features can be equivalently replaced within the spirit and principle of the present invention; such modifications or substitutions do not depart from the scope of the present invention.

Claims

1. A starting method of an engine in a dual-motor hybrid system, the dual-motor hybrid system including an engine, a first motor connected to the engine, and a clutch connected between the first motor and a transmission system; the starting method is characterized by comprising the following steps:

if so, generating a dragging start signal, sending the dragging start signal to a target component to be dragged to start the engine, and controlling the target component to output a corresponding pre-dragging torque within a set time length from the moment the dragging start signal is received;

after finishing outputting the pre-towing torque, increasing a towing torque of the target component to a maximum towing torque required to tow the engine to a target rotation speed to tow the engine to the target rotation speed, wherein the target component is the first motor or the clutch, and the pre-towing torque is smaller than the maximum towing torque.

2. The startup method of claim 1,

the current state data includes engine speed and throttle state or driver requested torque;

3. The startup method of claim 2,

the throttle state comprises throttle opening and throttle change rate;

4. A starting method according to claim 3,

the step of judging whether the starting mode intended by the driver is a smooth starting mode according to the acquired accelerator opening and accelerator change rate or the acquired driver request torque comprises the following steps of:

5. The startup method of claim 4,

the preset rotating speed threshold is 50 rpm;

the first accelerator opening threshold value is 70%;

the preset change rate threshold value is 300%/s;

6. The startup method according to any one of claims 1 to 5,

the set time length is 0.2-0.4 s;

the pre-dragging torque corresponding to the first motor is 15-30 N.m;

the pre-drag torque corresponding to the clutch is 2-4N · m.

7. The startup method according to any one of claims 1 to 5,

the dual-motor hybrid power system also comprises a second motor which is connected with the speed change system and used for driving wheels;

the starting method further comprises the following steps:

8. The startup method of claim 7,

the step of active damping control of the second electric machine comprises:

9. A starting device of an engine in a two-motor hybrid system, characterized by comprising a memory and a processor, the memory storing a control program, the control program being adapted to implement the starting method according to any one of claims 1-8 when executed by the processor.

10. A hybrid vehicle characterized by comprising a two-motor hybrid system and a starting apparatus of an engine in the two-motor hybrid system according to claim 9.