Control method and control system for protecting range extender engine

Abstract

The invention relates to the technical field of engine control, in particular to a control method and system for protecting a range extender engine. The control method comprises the steps that S1, an engine starting instruction is obtained; s2, a range extender engine is controlled to inject oil and ignite, and a starting motor assists the range extender engine in increasing the rotating speed; s3, when the range extender engine operates at the power generation rotating speed working condition, the theoretical air-fuel ratio and the actual air-fuel ratio are obtained; s4, determining an air-fuel ratio deviation value according to the theoretical air-fuel ratio and the actual air-fuel ratio; s5, whether the air-fuel ratio deviation value is larger than or equal to a preset deviation threshold value or not is judged, and if yes, an engine restart verification strategy is executed; and if not, the range extender engine is controlled to operate at the working condition of the power generation rotating speed. The air-fuel ratio deviation value verification is carried out in the starting stage of the range extender engine, it is ensured that the range extender engine operates under the reasonable air-fuel ratio deviation value condition, and waste gas and black smoke are prevented from losing an aftertreatment system.

Description

Technical Field

[0001] The present application relates to the field of engine control technology, and in particular to a control method and a control system for protecting a range extender engine. Background Art

[0002] In a range extender engine, the engine is used to charge the battery. While charging, the engine runs at the most efficient speed range, improving thermal efficiency.

[0003] The starting process of the range extender engine includes the starting phase, the speed adjustment phase and the steady-state operation phase. In the starting phase, the engine is ignited, and the starter motor drives the engine to quickly reach the idle speed condition. In the speed adjustment phase, the starter motor drives the engine to the power generation speed condition. In the steady-state operation phase, the engine maintains the power generation speed condition. At the same time, the engine controller needs to implement the smoke restriction strategy, adjust the engine operating parameters by detecting the exhaust smoke density, and prevent excessive black smoke emissions.

[0004] The range extender engine does not drive the wheels directly, and the gearbox is removed from its transmission system. Therefore, the speed of the range extender engine can only be adjusted by adjusting the operating conditions of the range extender engine. When the intake pipe of the range extender engine has problems such as air leakage, causing insufficient intake, the existing control strategy cannot automatically constrain the motor to drag the engine to run to the range extender engine condition. The motor drags the engine to the engine speed through speed control, and then performs torque control, causing the engine to run at a low air-fuel ratio, deteriorating combustion in the engine cylinder, and increasing exhaust temperature and smoke density to varying degrees. This control strategy will cause the exhaust smoke density to increase, and long-term operation of the range extender engine at a low air-fuel ratio will cause post-treatment system failure.

[0005] In order to prevent the range extender engine from operating in a low air-fuel ratio condition for a long time, the present application provides a control method for protecting the range extender engine. Summary of the invention

[0006] In order to overcome the problems existing in the related art, the first aspect of the present application provides a control method for protecting a range extender engine, comprising the following steps:

[0007] S1, obtaining an engine start command;

[0008] S2, controlling the range extender engine to inject fuel and ignite, and assisting the range extender engine to increase its speed through the starter motor; the starter motor is in transmission connection with the range extender engine; the operating condition of the range extender engine includes a power generation speed condition;

[0009] S3, when the range extender engine is running at the power generation speed condition, obtaining a theoretical air-fuel ratio and an actual air-fuel ratio;

[0010] S4. Determine the air-fuel ratio deviation value based on the theoretical air-fuel ratio and the actual air-fuel ratio;

[0011] S5. Determine whether the air-fuel ratio deviation value is greater than or equal to a preset deviation threshold. If so, execute the engine restart verification strategy; if not, control the range extender engine to operate under the power generation speed condition.

[0012] In one embodiment, the operating conditions of the range extender engine further include an idle condition; controlling the fuel injection and ignition of the range extender engine and using the starting motor to assist the range extender engine to increase its speed specifically includes:

[0013] Use the starting motor to increase the engine speed to idle speed;

[0014] When the range extender engine operates under the idle condition, monitor whether the range extender engine starts normally.

[0015] In one embodiment, using the starting motor to increase the engine speed to idle speed and monitoring whether the range extender engine starts normally when the range extender engine operates under the idle condition specifically includes:

[0016] S201. Use the starting motor to assist the range extender engine to operate under the idle condition;

[0017] S202. Control the starting motor to reduce its speed and interrupt the transmission, and adjust the fuel injection amount of the range extender engine to maintain the idle condition; S203. Monitor and determine whether the idle duration is greater than or equal to a first duration threshold. If so, control the range extender engine to operate under the power generation speed condition; if not, control the range extender engine to stop fuel injection and shut down.

[0018] In one embodiment, controlling the range extender engine to operate under the power generation speed condition specifically includes:

[0019] S2031. Control the starting motor to perform transmission;

[0020] S2032. Increase the speed of the range extender engine to the power generation speed;

[0021] S2033. Adjust the fuel injection amount to maintain the power generation speed condition;

[0022] S2034. Control the starting motor to interrupt the transmission.

[0023] In one embodiment, in the execution of the engine restart verification strategy, the engine restart verification strategy specifically includes:

[0024] S501. Obtain the number of idle times of the engine;

[0025] S502. Determine whether the number of idle runs is greater than or equal to a preset restart number. If so, control the range extender engine to cut off fuel and stop; if not, control the range extender engine to operate under the idle condition and execute step S2031.

[0026] In one embodiment, in the acquisition of the theoretical air-fuel ratio and the actual air-fuel ratio, the theoretical air-fuel ratio is obtained by looking up a table, and the actual air-fuel ratio is obtained by detecting with an oxygen sensor.

[0027] In one embodiment, the theoretical air-fuel ratio is obtained from a theoretical air-fuel ratio model constructed on a theoretical engine test bench.

[0028] In one embodiment, in the acquisition of the theoretical air-fuel ratio and the actual air-fuel ratio, the theoretical air-fuel ratio is obtained by looking up a table, and the actual air-fuel ratio is determined by the cyclic fuel injection quantity and the cyclic intake air quantity of the ECU control parameters.

[0029] In one embodiment, the theoretical air-fuel ratio is obtained from a theoretical air-fuel ratio model constructed on a theoretical engine test bench.

[0030] The second aspect of the present application provides a control system for protecting a range extender engine, which executes the steps in the method of the first aspect of the present application.

[0031] The technical solution provided by the present application may include the following beneficial effects:

[0032] In the present application, the range extender engine enters the power generation speed condition with the assistance of a starting motor, obtains the actual air-fuel ratio and the theoretical air-fuel ratio to calculate the air-fuel ratio deviation value. If the air-fuel ratio deviation value is greater than or equal to a preset deviation threshold, control the engine to cut off fuel and stop; otherwise, maintain the current condition. The present application verifies the air-fuel ratio deviation value in the starting stage of the range extender engine to ensure that the range extender engine operates under reasonable air-fuel ratio deviation value conditions and prevent the waste gas black smoke from damaging the after-treatment system.

[0033] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] By describing the exemplary embodiments of the present application in more detail in conjunction with the drawings, the above and other objects, features and advantages of the present application will become more obvious, wherein, in the exemplary embodiments of the present application, the same reference numerals generally represent the same components.

[0035] Figure 1 It is a schematic flowchart of the control method for protecting a range extender engine shown in the embodiments of the present application. DETAILED DESCRIPTION

[0036] The preferred embodiments of the present application will be described in more detail below with reference to the accompanying drawings. Although the preferred embodiments of the present application are shown in the accompanying drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to make the present application more thorough and complete, and to fully convey the scope of the present application to those skilled in the art.

[0037] The terms used in this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The singular forms of "a", "said" and "the" used in this application and the appended claims are also intended to include plural forms unless the context clearly indicates other meanings. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0038] It should be understood that although the terms "first", "second", "third", etc. may be used in this application to describe various information, this information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of this application, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0039] Embodiment 1

[0040] When the range extender engine has insufficient intake air, the existing control strategy will increase the injection amount to maintain the optimal speed. This control strategy will cause the exhaust smoke to increase, and the long-term operation of the range extender engine at a low air-fuel ratio will cause the after-treatment system to malfunction.

[0041] In order to prevent the range extender engine from operating in a low air-fuel ratio condition for a long time, the embodiment of the present application provides a control method for protecting the range extender engine, such as Figure 1 As shown, the following steps are included:

[0042] S1, obtaining an engine start command;

[0043] S2, controlling the range extender engine to inject fuel and ignite, and assisting the range extender engine to increase its speed through the starter motor; the starter motor is in transmission connection with the range extender engine; the operating condition of the range extender engine includes a power generation speed condition;

[0044] S3, when the range extender engine is running at the power generation speed condition, obtaining a theoretical air-fuel ratio and an actual air-fuel ratio;

[0045] S4. Determine the air-fuel ratio deviation value based on the theoretical air-fuel ratio and the actual air-fuel ratio;

[0046] It can be understood that the range extender engine includes internal combustion engines such as diesel engines and gasoline engines. In the embodiment of the diesel engine, step S2 is used to control the range extender engine to perform fuel injection and compression ignition. In the embodiment of the gasoline engine, step S2 is used to control the range extender engine to perform fuel injection and spark ignition.

[0047] Specifically, the power generation speed condition is that the engine outputs power at the speed of the best thermal efficiency. It can be understood that the best thermal efficiency is 1200 r / min to 1600 r / min. The best thermal efficiency conditions of engines of different models are different and are not limited herein.

[0048] Specifically, the actual air-fuel ratio is determined by the ECU control parameters to cycle the fuel injection amount and the intake air amount.

[0049] Specifically, the theoretical air-fuel ratio is obtained by querying the theoretical air-fuel ratio table. The theoretical air-fuel ratio table is pre-stored in a readable storage medium. On the engine bench test bench, the engine parameters are set based on different working conditions to construct a theoretical air-fuel ratio model. During actual operation, the electronic control data - theoretical air-fuel ratio table is determined through the constructed theoretical air-fuel ratio model. The theoretical air-fuel ratio is obtained by querying the electronic control data - theoretical air-fuel ratio table according to the real-time electronic control signal.

[0050] S5. Determine whether the air-fuel ratio deviation value is greater than or equal to the preset deviation threshold. If so, execute the engine restart verification strategy; if not, control the range extender engine to operate under the power generation speed condition.

[0051] Specifically, the air-fuel ratio deviation value is equal to the difference between the actual air-fuel ratio and the theoretical air-fuel ratio divided by the theoretical air-fuel ratio.

[0052] In a traditional engine, the air-fuel ratio is adjusted by the fuel injection system and the intake air system to adjust the output power and torque of the engine. When the exhaust gas smoke of the engine is too large, the air-fuel ratio is adjusted and the speed is changed.

[0053] However, the range extender engine is not equipped with a gearbox. The range extender engine immediately operates under the power generation speed condition after starting, so that the engine speed matches the generator demand. If there is a failure in the intake air system, the existing engine control strategy will increase the fuel injection amount to maintain the engine speed, resulting in too high exhaust gas smoke and easily causing a failure in the aftertreatment system.

[0054] In the embodiment of the present application, the range extender engine enters the power generation speed condition with the assistance of the starter motor, obtains the actual air-fuel ratio and the theoretical air-fuel ratio to calculate the air-fuel ratio deviation value, and if the air-fuel ratio deviation value is greater than or equal to the preset deviation threshold, the engine is controlled to cut off fuel and shut down; otherwise, the current condition is maintained. The embodiment of the present application verifies the air-fuel ratio deviation value during the start-up phase of the range extender engine to ensure that the range extender engine operates under reasonable air-fuel ratio deviation conditions to prevent exhaust gas black smoke from damaging the post-treatment system.

[0055] Embodiment 2

[0056] On the basis of the first embodiment, the embodiment of the present application further provides a control method for protecting the range extender engine, which further confirms the working status of the engine through a multi-step engine startup verification procedure to prevent the engine from being damaged.

[0057] The present application embodiment provides a control method for protecting a range extender engine, such as Figure 1 As shown, the following steps are included:

[0058] S1, obtaining an engine start command;

[0059] S2, controlling the range extender engine to inject fuel and ignite, and assisting the range extender engine to increase its speed through the starter motor; the starter motor is in transmission connection with the range extender engine; the operating condition of the range extender engine includes a power generation speed condition;

[0060] S3, when the range extender engine is running at a power generation speed condition, obtaining a theoretical air-fuel ratio and an actual air-fuel ratio;

[0061] S4, determining an air-fuel ratio deviation value according to the theoretical air-fuel ratio and the actual air-fuel ratio;

[0062] S5, determining whether the air-fuel ratio deviation value is greater than or equal to a preset deviation threshold value, and if so, executing the engine restart verification strategy; if not, controlling the range extender engine to operate at the power generation speed condition;

[0063] Furthermore, the operating condition of the range extender engine also includes an idle condition;

[0064] Before step S3, the embodiment of the present application performs idle speed verification and power generation speed verification when starting the range extender engine in step S2, including the following steps:

[0065] S201, raising the engine speed to idle speed by starting the motor;

[0066] S202, controlling the starter motor to interrupt transmission and adjusting the fuel injection amount to maintain the idle speed condition;

[0067] S203. Monitor and determine whether the idle duration is greater than or equal to the first duration threshold. If so, control the range extender engine to operate under the power generation speed condition; if not, control the range extender engine to cut off fuel and shut down.

[0068] In steps S202 and S203, the starting motor reduces the drag rotation speed so that the speed of the starting motor is 150 - 200 r / min lower than the idle speed of the range extender engine. Then, the starting motor interrupts the power, and the range extender engine is controlled to adjust the parameters to maintain idle operation. Monitor the idle duration of the range extender engine within the range of the idle speed ±30 r / min. If it reaches 1.5 s, send a "start successful" message and execute the next step.

[0069] Further, after step S203, controlling the range extender engine to operate under the power generation speed condition specifically includes:

[0070] S2031. Control the starting motor to perform transmission;

[0071] S2032. Increase the speed of the range extender engine to the power generation speed;

[0072] S2033. Adjust the fuel injection quantity to maintain the power generation speed;

[0073] S2034. Control the starting motor to interrupt the transmission.

[0074] In order to shorten the starting duration of the range extender engine, the embodiment of the present application uses the starting motor to assist the range extender engine, increases the engine speed to the idle condition and the power generation speed condition respectively, and completes the idle verification and the power generation speed verification respectively.

[0075] When the power generation speed verification is abnormal, execute the restart verification strategy in step S5, which specifically includes:

[0076] S501. Obtain the idle times of the engine;

[0077] S502. Determine whether the idle times are greater than or equal to the preset restart times. If so, control the range extender engine to cut off fuel and shut down; if not, control the range extender engine to operate under the idle condition and execute step S2031.

[0078] Damage to the intake system of the range extender engine will cause an abnormal reduction in the intake air volume. Existing range extender engines will increase the fuel injection volume to maintain the engine at the power generation speed condition. In the embodiments of the present application, when starting the engine, it is verified whether the engine is operating normally under the idle condition and the power generation speed condition respectively. If the engine has a fault, resulting in an abnormal condition of the range extender engine, the engine is restarted. The embodiments of the present application can perform start-up verification for the range extender engine and avoid the range extender engine from operating under abnormal conditions.

[0079] Embodiment III

[0080] A control system for protecting a range extender engine is used to execute the steps in the control method for protecting a range extender engine described in Embodiment I or Embodiment II.

[0081] The solution of the present application has been described in detail above with reference to the accompanying drawings. In the above embodiments, the descriptions of each embodiment have their own focuses. For the parts not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments. Those skilled in the art should also know that the actions and modules involved in the specification are not necessarily essential to the present application.

[0082] In addition, it can be understood that the steps in the method embodiments of the present application can be adjusted, combined, and deleted according to actual needs, and the modules in the device embodiments of the present application can be combined, divided, and deleted according to actual needs.

[0083] In addition, according to the method of the present application, it can also be implemented as a computer program or a computer program product, which includes computer program code instructions for executing some or all of the above steps of the method of the present application.

[0084] Alternatively, the present application can also be implemented as a non-transitory machine-readable storage medium (or computer-readable storage medium, or machine-readable storage medium), on which executable code (or computer program, or computer instruction code) is stored. When the executable code (or computer program, or computer instruction code) is executed by a processor of an electronic device (or an electronic device, a server, etc.), the processor executes some or all of the steps of the above method according to the present application.

[0085] Those skilled in the art will also understand that the various exemplary logical blocks, modules, circuits, and algorithm steps described in connection with the applications herein can be implemented as electronic hardware, computer software, or a combination of both.

[0086] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems and methods according to various embodiments of the present application. In this regard, each block in the flowchart or block diagram may represent a module, a segment of a program, or a portion of code, which contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than that marked in the accompanying drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in the reverse order, depending on the functions involved. It should also be noted that each block in the block diagram and / or flowchart, as well as combinations of blocks in the block diagram and / or flowchart, may be implemented by a dedicated hardware-based system that performs the specified functions or operations, or may be implemented by a combination of dedicated hardware and computer instructions.

[0087] The embodiments of the present application have been described above. The above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations are obvious to those of ordinary skill in the art in the technical field without departing from the scope and spirit of the described embodiments. The choice of terms used herein is intended to best explain the principles of the embodiments, the practical application, or the improvement of the technology in the market, or to enable other ordinary skill in the art in the technical field to understand the embodiments disclosed herein.

Claims

1. A control method for protecting a range extender engine, characterized in that: The following steps are involved: S1, obtaining an engine start command; S2, controlling the fuel injection and ignition of the range extender engine, and assisting the range extender engine to increase its speed by starting the motor; The starter motor is in transmission connection with the range extender engine; the operating condition of the range extender engine includes a power generation speed condition; S3, when the range extender engine is running at the power generation speed condition, obtaining a theoretical air-fuel ratio and an actual air-fuel ratio; S4, determining an air-fuel ratio deviation value according to the theoretical air-fuel ratio and the actual air-fuel ratio; S5. Determine whether the air-fuel ratio deviation value is greater than or equal to a preset deviation threshold value. If so, execute the engine restart verification strategy; if not, control the range extender engine to operate at the power generation speed condition.

2. A control method for protecting a range extender engine according to claim 1, characterized in that: The operating conditions of the range extender engine also include an idle condition; The controlling of the range extender engine fuel injection ignition and assisting the range extender engine to increase the speed by starting the motor specifically includes: The engine speed is increased to an idle speed by starting a motor, and when the range extender engine is running at the idle speed condition, whether the range extender engine is started normally is monitored.

3. A control method for protecting a range extender engine according to claim 2, characterized in that: The step of increasing the engine speed to the idle speed by starting the motor and monitoring whether the range extender engine is started normally when the range extender engine is running at the idle speed condition specifically includes: S201, assisting the range extender engine to operate at the idle speed condition by starting the motor; S202, controlling the starter motor to reduce the speed and interrupt the transmission, and adjusting the fuel injection amount of the range extender engine to maintain the idle speed condition; S203, monitoring and determining whether the idling time is greater than or equal to a first time threshold, if so, controlling the range extender engine to operate at the power generation speed; if not, controlling the range extender engine to cut off fuel and shut down.

4. A control method for protecting a range extender engine according to claim 3, characterized in that: Controlling the range extender engine to operate at the power generation speed condition specifically includes: S2031, controlling the starting motor to transmit; S2032, increasing the speed of the range extender engine to a power generation speed; S2033, adjusting the fuel injection amount to maintain the power generation speed operating condition; S2034, control the starting motor to interrupt transmission.

5. A control method for protecting a range extender engine according to claim 4, characterized in that: In the execution of the engine restart verification strategy, the engine restart verification strategy specifically includes: S501, obtaining the number of engine idling times; S502, determining whether the idle times are greater than or equal to the preset restart times, if so, controlling the range extender engine to cut off fuel and shut down; if not, controlling the range extender engine to operate at the idle condition, and executing step S2031.

6. A control method for protecting a range extender engine according to claim 1, characterized in that: In the process of obtaining the theoretical air-fuel ratio and the actual air-fuel ratio, the theoretical air-fuel ratio is obtained by looking up a table, and the actual air-fuel ratio is determined by ECU control parameters such as the cyclic injection amount and the cyclic intake amount.

7. A control method for protecting a range extender engine according to claim 6, characterized in that: The theoretical air-fuel ratio is obtained by using a theoretical air-fuel ratio model constructed on a theoretical bench of the engine.

8. A control system for protecting a range extender engine, characterized in that: Execute the steps of the method according to any one of claims 1 to 7.

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