Engine starting method

Abstract

The present invention belongs to the technical field of vehicle engines and discloses an engine starting method, comprising: step S1, diagnosing a fault of a vehicle high-voltage system, and if a fault exists, entering step S2; step S2, judging the running state of the vehicle engine, and if the vehicle engine speed is greater than a first speed threshold EngSpd set1 , it is determined that the vehicle engine is in a running state, and the process goes to step S4; otherwise, it is determined that the vehicle engine is not in a running state, and the process goes to step S3; Step S3, when the real-time vehicle speed is greater than the first vehicle speed threshold VS set1 When the first vehicle speed threshold VS set1 <Real-time vehicle speed<Second vehicle speed threshold VS set2 The vehicle engine adopts a quick start mode; step S4, determining the subsequent operation mode of the vehicle according to the fault diagnosis of the vehicle high-voltage system. The engine start method is conducive to improving the performance of the vehicle under high-voltage system failure, improving the user experience and satisfaction, and further enhancing the market competitiveness of the product.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle engines, and in particular to an engine starting method. Background Art

[0002] Hybrid vehicles have always been a hot topic for research by various automobile manufacturers due to their low energy consumption. Hybrid vehicles are based on traditional power and have added high-voltage systems consisting of high-voltage batteries, high-voltage motors, DCDC and other components, as well as their corresponding control systems. Traditional power failure handling methods are mature, while high-voltage system failure handling is rapidly improving. After a component in the high-voltage system fails, how to use the engine to continue to provide power to the vehicle to ensure that the vehicle can continue to drive is a key issue that needs attention.

[0003] Therefore, there is an urgent need for a control method that can effectively start the engine under various high-voltage system failures. Summary of the invention

[0004] The object of the present invention is to provide an engine starting method, which is beneficial to improving the performance of the vehicle under high-voltage system failure.

[0005] To achieve this object, the present invention adopts the following technical solutions:

[0006] An engine starting method, comprising:

[0007] Step S1, diagnose the fault of the vehicle high-voltage system, if there is a fault, proceed to step S2;

[0008] Step S2: Determine the running state of the vehicle engine. If the vehicle engine speed is greater than the first speed threshold EngSpd set1 , it is determined that the vehicle engine is in a running state, and the process goes to step S4; otherwise, it is determined that the vehicle engine is not in a running state, and the process goes to step S3;

[0009] Step S3, confirm the vehicle engine starting mode; when the real-time vehicle speed> the first vehicle speed threshold VS set1 When the first vehicle speed threshold VS set1 > the real-time vehicle speed > the second vehicle speed threshold VS set2 When the vehicle engine is started quickly,

[0010] Step S4: determining a subsequent operation mode of the vehicle according to the fault diagnosis of the vehicle high-voltage system and the hybrid configuration of the vehicle.

[0011] As a preferred technical solution of the present invention, in step S1, the vehicle high-voltage system includes a high-voltage battery, a high-voltage motor, a high-voltage circuit and a control system.

[0012] As a preferred technical solution of the present invention, in step S2, the first speed threshold EngSpd set1 It refers to the lowest speed at which the vehicle engine can achieve smooth and autonomous combustion with direct injection ignition at an air-fuel ratio of 1 in the fuel-off state.

[0013] As a preferred technical solution of the present invention, in step S3, the first vehicle speed threshold VS set1 for:

[0014]

[0015] In the formula, i max is the maximum transmission ratio in the vehicle's forward gear, i main is the speed ratio of the vehicle's main reducer, r tire is the vehicle tire radius.

[0016] As a preferred technical solution of the present invention, in step S3, the second vehicle speed threshold VS set2 for:

[0017]

[0018] In the formula, EngSpd set2 is a second speed threshold, and the second speed threshold is the minimum speed at which the vehicle engine can be started by fuel injection and ignition.

[0019] As a preferred technical solution of the present invention, in step S3, the smooth start mode includes:

[0020] Step S310, increasing the oil pressure of the separation clutch to make the transmission torque of the separation clutch zero, and at the same time reducing the gear position of the transmission to the lowest gear position;

[0021] Step S311: gradually increase the engagement pressure of the separation clutch at a fixed rate until the vehicle engine speed is greater than the first speed threshold EngSpd set1 ;

[0022] Step S312: the vehicle engine is directly ignited with an air-fuel ratio of 1 to achieve autonomous combustion. When the vehicle engine torque is greater than a torque threshold and is maintained for a certain period of time, the vehicle engine is smoothly started.

[0023] As a preferred technical solution of the present invention, in step S311, the fixed rate refers to the maximum rate of change of the separation clutch engagement pressure that ensures that the smoothness of the entire vehicle is not affected when the separation clutch drags the engine to rotate.

[0024] As a preferred technical solution of the present invention, in step S3, the quick start method includes:

[0025] Step S320, lowering the gear position of the transmission to the lowest gear position;

[0026] Step S321: Increase the engagement pressure of the separation clutch to a fixed value at the maximum rate until the vehicle engine speed is greater than the second speed threshold EngSpd set2 ;

[0027] Step 323, the vehicle engine realizes autonomous combustion by direct fuel injection ignition with an air-fuel ratio of 1, the vehicle engine speed rises, and at the same time, after a certain period of time since the vehicle engine starts fuel injection ignition, the pressure of the separation clutch is quickly separated; when the vehicle engine torque is greater than the torque threshold and maintained for a certain period of time, the vehicle engine is quickly started.

[0028] As a preferred technical solution of the present invention, in step S321, the fixed value means that the transmission torque of the separation clutch is greater than the separation clutch pressure corresponding to the maximum torque required to drag the vehicle engine.

[0029] As a preferred technical solution of the present invention, in step S4, the subsequent operation mode of the vehicle is determined by comparing the fault information association table based on the fault diagnosis of the vehicle high-voltage system and the hybrid configuration of the vehicle.

[0030] Beneficial effects of the present invention:

[0031] The engine starting method of the present invention can perform fault diagnosis on the vehicle's high-voltage system. When a fault occurs in the vehicle's high-voltage system, the operating status of the vehicle's engine can be confirmed at the first time. If the vehicle's engine is not in an operating state, the vehicle's engine can be started using two starting methods, namely, smooth start and quick start. After the vehicle's engine is successfully started, the subsequent operating mode of the vehicle can be determined based on the fault diagnosis of the vehicle's high-voltage system, which is beneficial to improving the performance of the vehicle under high-voltage system failure, improving the user experience and satisfaction, and further enhancing the market competitiveness of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a flow chart of an engine starting method according to an embodiment of the present invention;

[0033] Figure 2 It is a schematic diagram of the control process of a vehicle engine using a smooth start mode;

[0034] Figure 3 It is a schematic diagram of the control process of a vehicle engine using a quick start method. DETAILED DESCRIPTION

[0035] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar parts or parts having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0036] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection, it can be a mechanical connection or an electrical connection, it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0037] In the description of the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include the first feature being in direct contact with the second feature, or may include the first feature being in contact with the second feature through another feature between them instead of being in direct contact. Moreover, a first feature being "above", "above" and "above" a second feature includes the first feature being directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes the first feature being directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0038] In the description of this embodiment, the terms "upper", "lower", "right", etc., directions or positional relationships are based on the directions or positional relationships shown in the drawings, and are only for the convenience of description and simplification of operation, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.

[0039] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0040] like Figure 1 As shown, the present invention provides an engine starting method, comprising:

[0041] Step S1, diagnose the fault of the vehicle high-voltage system, if there is a fault, proceed to step S2;

[0042] In this step, the vehicle's high-voltage system includes a high-voltage battery, a high-voltage motor, a high-voltage circuit and a control system. Fault diagnosis is performed on a single or multiple components in the vehicle's high-voltage system to determine whether there is a serious fault. A serious fault here means that the high-voltage battery and the high-voltage motor cannot transfer energy to the outside, that is, the charge and discharge power of the high-voltage battery is zero or the available drive recovery torque of the high-voltage motor is zero. If it is determined that there is a serious fault, go to step S2;

[0043] Step S2: Determine the running state of the vehicle engine. If the vehicle engine speed is greater than the first speed threshold EngSpd set1 , it is determined that the vehicle engine is in a running state, and the process goes to step S4; otherwise, it is determined that the vehicle engine is not in a running state, and the process goes to step S3;

[0044] In this step, the running state of the vehicle engine at the time of the fault is confirmed. If the vehicle engine speed is greater than the first speed threshold EngSpd set1 , then the vehicle engine is deemed to be in a running state, and the first speed threshold EngSpd set1 It refers to the lowest speed at which the vehicle engine can achieve smooth and autonomous combustion with direct fuel injection ignition at an air-fuel ratio of 1 in the fuel-off state. This speed value is greater than the vehicle engine idle speed and is generally equivalent to the speed at which the fuel supply is restored after the fuel is cut off in the coasting condition of the whole vehicle. In this step, if it is determined that the vehicle engine is not in a running state, proceed to the next step S3. If it is determined that the vehicle engine is in a running state, proceed directly to step S4 to determine the subsequent operation mode of the vehicle when the vehicle engine is started.

[0045] Step S3: confirm the vehicle engine starting mode; when the real-time vehicle speed is greater than the first vehicle speed threshold VS set1 When the first vehicle speed threshold VS set1 >Real-time vehicle speed>Second vehicle speed threshold VS set2 When the vehicle engine is started quickly;

[0046] In this step, the first vehicle speed threshold VS set1 The following formula is used to calculate:

[0047]

[0048] In the formula, i max The maximum transmission ratio among the vehicle's forward gears, generally the transmission ratio of the vehicle's lowest gear. If the vehicle has only one gear, the speed ratio of that gear is selected; i main is the speed ratio of the vehicle's main reducer, r tire is the vehicle tire radius.

[0049] Second vehicle speed threshold VS set2 for:

[0050]

[0051] In the formula, EngSpd set2 The second speed threshold is the minimum speed at which the vehicle engine can be started by fuel injection and ignition, and its speed value is the engine speed that can be dragged by a traditional 12V starter.

[0052] The first vehicle speed threshold VS is calculated by the above formula: set1 and the second vehicle speed threshold VS set2 After that, if the real-time vehicle speed is greater than the first vehicle speed threshold VS set1 When the vehicle engine is started in a smooth start mode; if the first vehicle speed threshold VS set1 >When the real-time vehicle speed is >the second vehicle speed threshold, the vehicle engine is started in a quick start mode.

[0053] More specifically, Figure 2 In the process shown, the smooth start method in step S3 includes:

[0054] Step S310, increase the oil pressure of the separation clutch to make the transmission torque of the separation clutch zero, and at the same time reduce the gear of the transmission to the lowest gear; this stage is the clutch oil filling stage, and the separation clutch controls the oil pressure in the oil chamber to increase to a state that can overcome the spring force of the return spring and the clutch transmission torque is zero, and at the same time reduces the gear of the transmission to the lowest gear. If the hybrid configuration (for example, the dual-motor P13 hybrid configuration) has only one gear, there is no need to perform a gear change operation.

[0055] Step S311: gradually increase the engagement pressure of the separation clutch at a fixed rate until the vehicle engine speed is greater than the first speed threshold EngSpd set1 ; This stage is the drag stage. The fixed rate refers to the maximum rate of change of the separation clutch engagement pressure when the separation clutch drags the engine to rotate, ensuring that the smoothness of the vehicle is not affected. When the vehicle engine speed is greater than the first speed threshold EngSpd set1 Entering the autonomous combustion stage;

[0056] Step S312: This stage is the autonomous combustion stage. The vehicle engine directly injects fuel and ignites with an air-fuel ratio of 1 to achieve autonomous combustion. When the vehicle engine torque is greater than the torque threshold and is maintained for a certain period of time, the vehicle engine starts smoothly.

[0057] More specifically, Figure 3 In the process shown, the quick start method in step S3 includes:

[0058] Step S320, reduce the gear of the transmission to the lowest gear; this stage is the gear shifting stage, and the gear of the transmission is reduced to the lowest gear. If the hybrid configuration (such as the dual-motor P13 hybrid configuration) has only one gear, the current stage is skipped.

[0059] Step S321: Increase the engagement pressure of the separation clutch to a fixed value at the maximum rate until the vehicle engine speed is greater than the second speed threshold EngSpd set2 ; This stage is the dragging stage.

[0060] The clutch engagement pressure will increase to a fixed value at the maximum rate until the engine speed is greater than the second speed threshold EngSpd set2 and maintain it for a certain period of time; specifically, the fixed value means that the transmission torque of the separation clutch is greater than the separation clutch pressure corresponding to the maximum torque required to drag the vehicle engine, the purpose is to quickly drag the engine speed; when the engine speed is greater than the second speed threshold EngSpd set2 When the combustion lasts for a certain period of time, the process proceeds to step S323, and the autonomous combustion stage is entered;

[0061] Step 323, the vehicle engine directly injects fuel and ignites with an air-fuel ratio of 1 to achieve autonomous combustion, the vehicle engine speed rises, and at the same time, after a certain period of time since the vehicle engine starts to inject fuel and ignite, the pressure of the separation clutch is quickly released; when the vehicle engine torque is greater than the torque threshold and is maintained for a certain period of time, the vehicle engine is quickly started.

[0062] After the vehicle engine is successfully started by any of the above two starting methods, the process proceeds to step S4;

[0063] Step S4, determining the subsequent operation mode of the vehicle according to the fault diagnosis of the vehicle high-voltage system and the hybrid configuration of the vehicle; in this step, the subsequent operation mode of the vehicle is determined according to the fault diagnosis of the vehicle high-voltage system and the hybrid configuration of the vehicle, and the fault information association table is compared. For example, refer to Table 1, which is a fault information association table.

[0064] Table 1

[0065]

[0066] Taking the P13 dual-motor hybrid configuration and the P2 hybrid configuration as examples, illustratively, if the fault diagnosis of the vehicle's high-voltage system is determined to be a high-voltage battery fault, a serious high-voltage battery fault will be displayed on the vehicle instrument. For the P13 dual-motor hybrid configuration, the series mode driving mode is adopted as the preferred operating mode after the vehicle engine is started. For the P2 hybrid configuration, the vehicle engine driving mode is adopted as the preferred operating mode after the vehicle engine is started. Similarly, the preferred operating mode after the engine of each type of hybrid configuration vehicle is started is obtained according to the pre-set fault information association table.

[0067] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. An engine starting method, characterized in that: include: Step S1, diagnose the fault of the vehicle high-voltage system, if there is a fault, proceed to step S2; Step S2: Determine the running state of the vehicle engine. If the vehicle engine speed is greater than the first speed threshold EngSpd set1 , it is determined that the vehicle engine is in a running state, and the process goes to step S4; otherwise, it is determined that the vehicle engine is not in a running state, and the process goes to step S3; Step S3, confirm the vehicle engine starting mode; when the real-time vehicle speed> the first vehicle speed threshold VS set1 When the first vehicle speed threshold VS set1 > the real-time vehicle speed > the second vehicle speed threshold VS set2 When the vehicle engine is started quickly, Step S4, determining a subsequent operation mode of the vehicle according to the fault diagnosis of the vehicle high-voltage system and the hybrid configuration of the vehicle; In step S3, the smooth start mode includes: Step S310, increasing the oil pressure of the separation clutch to make the transmission torque of the separation clutch zero, and at the same time reducing the gear position of the transmission to the lowest gear position; Step S311: gradually increase the engagement pressure of the separation clutch at a fixed rate until the vehicle engine speed is greater than the first speed threshold EngSpd set1 ; Step S312: the vehicle engine is directly ignited by fuel injection with an air-fuel ratio of 1 to achieve autonomous combustion. When the vehicle engine torque is greater than a torque threshold and is maintained for a certain period of time, the vehicle engine is smoothly started; In step S3, the quick start method includes: Step S320, lowering the gear position of the transmission to the lowest gear position; Step S321: Increase the engagement pressure of the separation clutch to a fixed value at the maximum rate until the vehicle engine speed is greater than the second speed threshold EngSpd set2 ; Step 323, the vehicle engine realizes autonomous combustion by direct fuel injection ignition with an air-fuel ratio of 1, the vehicle engine speed rises, and at the same time, after a certain period of time since the vehicle engine starts fuel injection ignition, the pressure of the separation clutch is quickly separated; when the vehicle engine torque is greater than the torque threshold and maintained for a certain period of time, the vehicle engine is quickly started.

2. The engine starting method according to claim 1, characterized in that: In the step S1, the vehicle high-voltage system includes a high-voltage battery, a high-voltage motor, a high-voltage circuit and a control system.

3. The engine starting method according to claim 1, characterized in that: In step S2, the first speed threshold EngSpd set1 It refers to the lowest speed at which the vehicle engine can achieve smooth and autonomous combustion with direct injection ignition at an air-fuel ratio of 1 in the fuel-off state.

4. The engine starting method according to claim 1, characterized in that: In step S3, the first vehicle speed threshold VS set1 for: In the formula, i max is the maximum transmission ratio in the vehicle's forward gear, i main is the speed ratio of the vehicle's main reducer, r tire is the vehicle tire radius.

5. The engine starting method according to claim 4, characterized in that: In step S3, the second vehicle speed threshold VS set2 for: In the formula, EngSpd set2 is a second speed threshold, and the second speed threshold is the minimum speed at which the vehicle engine can be started by fuel injection and ignition.

6. The engine starting method according to claim 1, characterized in that: In step S311, the fixed rate refers to the maximum rate of change of the separation clutch engagement pressure that ensures that the smoothness of the entire vehicle is not affected when the separation clutch drags the engine to rotate.

7. The engine starting method according to claim 1, characterized in that: In the step S321, the fixed value means that the transmission torque of the separation clutch is greater than the separation clutch pressure corresponding to the maximum torque required to drag the vehicle engine.

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