A starting fuel injection control method for a hybrid vehicle

Abstract

The application relates to a starting fuel injection control method of a hybrid vehicle, which considers emission, and comprises an EHC heating circuit and a mixed heating circuit; the EHC heating circuit comprises a bypass valve, an EHC, a TWC, a GPF and a DeNOx connected in sequence, and the DeNOx is connected with the outside atmosphere; the mixed heating circuit comprises a bypass valve, a DOC, an EHC, a TWC, a GPF and a DeNOx connected in sequence, and the DeNOx is connected with the outside atmosphere; a temperature sensor T1 is arranged at the inlet of the EHC, a temperature sensor T2 is arranged at the inlet of the TWC, and a temperature sensor T3 is arranged at the inlet of the DeNOx; the method further comprises a hybrid control unit and a starting control unit; the bypass valve is connected with an engine, and the starting working mode is switched by opening and closing of the bypass valve. Compared with the prior art, the application can make the hybrid vehicle reach the best starting state in a short time under the low-temperature and power feeding environment, effectively reduce the emission in the engine starting process, and simultaneously consider the power performance and the economy of the vehicle.

Description

Technical Field

[0001] This invention relates to the field of hybrid vehicle technology, and in particular to a starting fuel injection control method for hybrid vehicles that takes emissions into account. Background Technology

[0002] Both Euro 6d and China 6b emission regulations include the Real Drive Emission (RDE) test to monitor the emission levels of vehicles during actual driving.

[0003] Hybrid electric vehicles (HEVs) have at least two power sources, typically one being an engine and the other a battery. The energy required for vehicle operation comes partly from the internal combustion engine, which converts the chemical energy of fuel into mechanical energy; and partly from the battery, which converts electrical energy into mechanical energy via an electric motor. HEVs operate in various modes, including pure electric drive, pure internal combustion engine drive, charging while driving, and hybrid drive.

[0004] Hybrid vehicles, whether equipped with diesel or gasoline engines, have high cold-start emissions. During startup, the engine exhaust temperature is low, and the efficiency of the catalyst in the exhaust aftertreatment system in catalytic conversion of exhaust gases is also low, leading to increased cold-start emissions.

[0005] In low-load conditions, hybrid vehicles shut down their engines, the after-treatment system stops working, and the car enters pure electric mode, unlike traditional gasoline vehicles where the engine runs continuously even at idle and the after-treatment system remains operational. Therefore, if the exhaust after-treatment system can be preheated purposefully during driving, based on the vehicle's status, and its temperature controlled within a reasonable range to avoid cold starts, emissions generated during engine start-up can be minimized.

[0006] Existing patents primarily focus on the application and control of electrically heated catalytic converters (EHC). Patent CN114060130A discloses an exhaust aftertreatment system for a hybrid vehicle, which uses an EHC heater to heat the system when the engine needs to operate. Patent CN115492665A discloses a variable-power EHC that adjusts the electric heating power appropriately for different low-temperature operating conditions of the engine. However, it has shortcomings: it does not consider battery depletion, where insufficient power may prevent the EHC from heating to the target power; and it also addresses the time required for the engine to start while the EHC is heating up. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art by providing a starting fuel injection control method for hybrid electric vehicles that takes into account emissions, enabling hybrid electric vehicles to reach the optimal starting state in a short time under low temperature and power depletion environments, effectively reducing emissions during engine starting, while taking into account the vehicle's power and economy.

[0008] The objective of this invention can be achieved through the following technical solutions:

[0009] This invention provides a starting fuel injection control method for hybrid electric vehicles that takes emissions into account, including an EHC heating circuit and a hybrid heating circuit;

[0010] The EHC heating circuit includes a bypass valve, EHC, TWC (three-way catalytic converter), GPF (particulate filter), and DeNOx (nitrogen oxide reduction catalyst) connected in sequence. In the EHC heating circuit, the bypass valve is in the closed state, and the DeNOx is connected to the outside atmosphere.

[0011] The hybrid heating circuit includes a bypass valve, DOC (catalytic converter), EHC, TWC, GPF, and DeNOx connected in sequence. The bypass valve is in the open state in the hybrid heating circuit, and DeNOx is connected to the outside atmosphere.

[0012] TWC (three-way catalytic converter), GPF (particulate filter), and DeNOx (nitrogen oxide reduction catalyst) form the engine exhaust aftertreatment system. Gaseous emissions such as THC, NOx, and CO are reacted away by the TWC; the GPF is used to capture particulate matter (PN) in the exhaust gas; and the DeNOx is used to treat NOx pollutants under lean-burn conditions.

[0013] Temperature sensor T1 is installed at the EHC inlet, temperature sensor T2 is installed at the TWC inlet, and temperature sensor T3 is installed at the DeNOx inlet.

[0014] It also includes a hybrid power control unit and a starting control unit. The starting control unit is connected in communication with temperature sensor T1, temperature sensor T2, temperature sensor T3, the engine, and the hybrid power control unit. The hybrid power control unit is used to obtain the target power value of the engine and the required time for engine power output. The starting control unit is used to obtain data from the hybrid power control unit and temperature data and control the engine and bypass valve.

[0015] The bypass valve is connected to the engine, and the starting working mode is switched by opening and closing the bypass valve;

[0016] The starting control unit receives data from the hybrid power control unit and calculates the optimal operating temperature T. maxThe starting control unit detects the initial temperature of the aftertreatment system, which is the initial temperature of the DeNOx inlet detected by temperature sensor T3, and determines whether T3 in the aftertreatment system has reached the optimal operating temperature T. max ;

[0017] If this is achieved, the starting control unit controls the engine to start normally;

[0018] If the heating power P1 is not reached, the start control unit calculates the heating power P1 and starts EHC heating;

[0019] Then determine whether P1 is less than the power P' allowed by the EHC battery capacity. If "yes", that is, P1 is less than P', and the EHC can reach the minimum start-up temperature T2 after heating. min It enters the low-temperature start-up heating mode and reaches the optimal operating temperature T3 within the specified time. max If "No", meaning P1 is greater than or equal to P', or T2 does not reach the minimum start-up temperature T after EHC heating. min Then, it will enter a low-temperature start-up and mixing heating process until T3 reaches the optimal operating temperature T. max ;

[0020] During the low-temperature start-up heating process, the start-up control unit controls the engine fuel injection to achieve a rich combustion condition with high exhaust temperature; the low-temperature start-up mixing heating process is as follows:

[0021] P2 is the heating power of DOC. When the engine is started, the secondary fuel injection quantity is obtained based on the heating power P2 of DOC. During the heating process, the temperatures T1, T2, and T3 in the exhaust pipe are monitored in real time, and the temperature difference between T1, T2, and T3 is calculated.

[0022] If T3≥T n Continue heating the mixture until T3 reaches its optimal operating temperature T. max ;

[0023] If T3 < T n Then, based on the magnitude of the temperature difference, the heating power P2 of DOC increases to P2 + ΔP. 31 This means increasing the amount of fuel injected in the second stage, causing the DOC to further oxidize the fuel and raise its temperature until it reaches T. n ΔP 31 This is the power calculated based on the temperature difference between T1 and T3. n The temperature at which the catalyst used in DeNOx achieves a catalytic conversion efficiency greater than 80%; the starting control unit sets the starting heating time t and detects the ambient temperature to calculate the engine's optimal operating temperature T. maxThe required total heating power P is allocated to the heating power P1 of EHC and the heating power P2 of DOC; during the mixed heating process at low temperature start-up, the bypass valve is in the open state; ΔP 31 The power is calculated based on the temperature difference between T1 and T3. T varies for different catalysts. n It varies, but is generally 150-200℃.

[0024] Furthermore, the engine is connected to the bypass valve via a pipe, and the engine transmits exhaust gas through the pipe.

[0025] Furthermore, the hybrid power control unit is communicatively connected to the vehicle sensors and the driver's pedal. The hybrid power control unit receives signals from the vehicle sensors and the driver's pedal and calculates the total target power value of the vehicle.

[0026] Furthermore, the hybrid power control unit allocates the total target power value of the vehicle to the engine and the motor, and outputs the target power value of the engine and the required time for engine power output to the starting control unit.

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] (1) The present invention can effectively heat the aftertreatment system even when the battery is depleted and the EHC cannot work, so as to meet the RDE starting emission requirements of hybrid electric vehicles.

[0029] (2) The time required for the low-temperature multi-stage heating after-treatment system of the present invention is greatly reduced, thereby controlling the emissions generated during engine start-up to a minimum. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of a start-up fuel injection control system for hybrid electric vehicles that takes emissions into account.

[0031] Figure 2 A flowchart of a starting fuel injection control method for hybrid electric vehicles that takes emissions into account.

[0032] Figure 3 This is a flowchart of the mixing and heating process under low-temperature start-up. Detailed Implementation

[0033] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. Component models, material names, connection structures, control methods, algorithms, and other features not explicitly described in this technical solution are considered common technical features disclosed in the prior art.

[0034] Example 1

[0035] This embodiment provides a starting fuel injection control method for hybrid electric vehicles that takes emissions into account, such as... Figure 1-3 As shown, it includes an EHC heating circuit and a hybrid heating circuit;

[0036] The EHC heating circuit includes a bypass valve, EHC, TWC (three-way catalytic converter), GPF (particulate filter), and DeNOx (nitrogen oxide reduction catalyst) connected in sequence. In the EHC heating circuit, the bypass valve is in the closed state, and the DeNOx is connected to the outside atmosphere.

[0037] The hybrid heating circuit includes a bypass valve, DOC (catalytic converter), EHC, TWC, GPF, and DeNOx connected in sequence. The bypass valve is in the open state in the hybrid heating circuit, and DeNOx is connected to the outside atmosphere.

[0038] TWC (three-way catalytic converter), GPF (particulate filter), and DeNOx (nitrogen oxide reduction catalyst) form the engine exhaust aftertreatment system. Gaseous emissions such as THC, NOx, and CO are reacted away by the TWC; the GPF is used to capture particulate matter (PN) in the exhaust gas; and the DeNOx is used to treat NOx pollutants under lean-burn conditions.

[0039] Temperature sensor T1 is installed at the EHC inlet, temperature sensor T2 is installed at the TWC inlet, and temperature sensor T3 is installed at the DeNOx inlet.

[0040] It also includes a hybrid power control unit and a starting control unit. The starting control unit is connected in communication with temperature sensor T1, temperature sensor T2, temperature sensor T3, the engine, and the hybrid power control unit. The hybrid power control unit is used to obtain the target power value of the engine and the required time for engine power output. The starting control unit is used to obtain data from the hybrid power control unit and temperature data and control the engine and bypass valve.

[0041] The bypass valve is connected to the engine, and the starting working mode is switched by opening and closing the bypass valve;

[0042] The starting control unit receives data from the hybrid power control unit and calculates the optimal operating temperature T. max The starting control unit detects the initial temperature of the aftertreatment system, which is the initial temperature of the DeNOx inlet detected by temperature sensor T3, and determines whether T3 in the aftertreatment system has reached the optimal operating temperature T. max ;

[0043] If this is achieved, the starting control unit controls the engine to start normally;

[0044] If the heating power P1 is not reached, the start control unit calculates the heating power P1 and starts EHC heating;

[0045] Then determine whether P1 is less than the power P' allowed by the EHC battery capacity. If "yes", that is, P1 is less than P', and the EHC can reach the minimum start-up temperature T2 after heating. min It enters the low-temperature start-up heating mode and reaches the optimal operating temperature T3 within the specified time. max If "No", meaning P1 is greater than or equal to P', or T2 does not reach the minimum start-up temperature T after EHC heating. min Then, it will enter a low-temperature start-up and mixing heating process until T3 reaches the optimal operating temperature T. max ;

[0046] During the low-temperature start-up heating process, the start-up control unit controls the engine fuel injection to achieve a rich combustion condition with high exhaust temperature; the low-temperature start-up mixing heating process is as follows:

[0047] P2 is the heating power of DOC. When the engine is started, the secondary fuel injection quantity is obtained based on the heating power P2 of DOC. During the heating process, the temperatures T1, T2, and T3 in the exhaust pipe are monitored in real time, and the temperature difference between T1, T2, and T3 is calculated.

[0048] If T3≥T n Continue heating the mixture until T3 reaches its optimal operating temperature T. max ;

[0049] If T3 < T n Then, based on the magnitude of the temperature difference, the heating power P2 of DOC increases to P2 + ΔP. 31 This means increasing the amount of fuel injected in the second stage, causing the DOC to further oxidize the fuel and raise its temperature until it reaches T. n ΔP 31 This is the power calculated based on the temperature difference between T1 and T3. n The temperature at which the catalyst used in DeNOx achieves a catalytic conversion efficiency greater than 80%; the starting control unit sets the starting heating time t and detects the ambient temperature to calculate the engine's optimal operating temperature T. max The required total heating power P is allocated to the heating power P1 of EHC and the heating power P2 of DOC; during the mixed heating process at low temperature start-up, the bypass valve is in the open state; ΔP 31 The power is calculated based on the temperature difference between T1 and T3. T varies for different catalysts. n It varies, but is generally 150-200℃.

[0050] In a specific implementation, the engine is connected to the bypass valve via a pipeline, and the engine transmits exhaust gas through the pipeline.

[0051] In a specific implementation, the hybrid power control unit is communicatively connected to the vehicle sensors and the driver's pedal. The hybrid power control unit receives signals from the vehicle sensors and the driver's pedal and calculates the total target power value of the vehicle.

[0052] In a specific implementation, the hybrid power control unit allocates the total target power value of the vehicle to the engine and the motor, and the hybrid power control unit outputs the target power value of the engine and the required time for engine power output to the starting control unit.

[0053] Components not described in detail in this embodiment are all existing components that can be purchased through public channels.

[0054] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A starting fuel injection control method for hybrid electric vehicles that takes into account emissions, characterized in that, Including EHC heating circuits and hybrid heating circuits; The EHC heating circuit includes a bypass valve, EHC, TWC, GPF, and DeNOx connected in sequence. The bypass valve in the EHC heating circuit is in the closed state, and the DeNOx is connected to the outside atmosphere. The hybrid heating circuit includes a bypass valve, DOC, EHC, TWC, GPF, and DeNOx connected in sequence. The bypass valve in the hybrid heating circuit is in the open state, and the DeNOx is connected to the outside atmosphere. Temperature sensor T1 is provided at the EHC inlet, temperature sensor T2 is provided at the TWC inlet, and temperature sensor T3 is provided at the DeNOx inlet; It also includes a hybrid power control unit and a starting control unit. The starting control unit is communicatively connected to the temperature sensor T1, temperature sensor T2, temperature sensor T3, engine, and the hybrid power control unit. The hybrid power control unit is used to obtain the target power value of the engine and the required time for engine power output. The starting control unit is used to obtain the data from the hybrid power control unit and the temperature data measured by the sensors, and to control the engine and the bypass valve. The bypass valve is connected to the engine, and the starting working mode is switched by opening and closing the bypass valve; The starting control unit receives data from the hybrid power control unit and calculates the optimal operating temperature T. max The starting control unit detects the initial temperature of the aftertreatment system, which is the initial temperature of the DeNOx inlet detected by temperature sensor T3, and determines whether T3 in the aftertreatment system has reached the optimal operating temperature T. max ; If this is achieved, the starting control unit controls the engine to start normally; If the target is not reached, the start control unit calculates the heating power P1 and activates EHC heating. Then determine whether P1 is less than the power P' allowed by the EHC battery capacity. If "yes", that is, P1 is less than P', and the EHC can reach the minimum start-up temperature T2 after heating. min It enters the low-temperature start-up heating mode and reaches the optimal operating temperature T3 within the specified time. max If "No", meaning P1 is greater than or equal to P', or T2 does not reach the minimum start-up temperature T after EHC heating. min Then, it will enter a low-temperature start-up and mixing heating process until T3 reaches the optimal operating temperature T. max ; During the low-temperature start-up heating process, the start-up control unit controls the engine fuel injection to achieve a rich combustion condition with high exhaust temperature; the low-temperature start-up mixing heating process is as follows: P2 is the heating power of DOC. When the engine is started, the secondary fuel injection quantity is obtained based on the heating power P2 of DOC. During the heating process, the temperatures T1, T2, and T3 in the exhaust pipe are monitored in real time, and the temperature difference between T1, T2, and T3 is calculated. If T3≥T n Continue heating the mixture until T3 reaches its optimal operating temperature T. max ; If T3 < T n Then, based on the magnitude of the temperature difference, the heating power P2 of DOC increases to P2 + ΔP. 31 This means increasing the amount of fuel injected in the second stage, causing the DOC to further oxidize the fuel and raise its temperature until it reaches T. n T n The temperature at which the catalyst used in DeNOx achieves a catalytic conversion efficiency greater than 80%; the starting control unit sets the starting heating time t and detects the ambient temperature to calculate the engine's optimal operating temperature T. max The required total heating power P is allocated to the heating power P1 of EHC and the heating power P2 of DOC; during the mixed heating process at low temperature start-up, the bypass valve is in the open state; ΔP 31 The power is calculated based on the temperature difference between T1 and T3.

2. The starting fuel injection control method for a hybrid electric vehicle that takes into account emissions, as described in claim 1, is characterized in that... The engine is connected to the bypass valve via a pipe, and the engine transmits exhaust gas through the pipe.

3. The starting fuel injection control method for a hybrid electric vehicle that takes into account emissions, as described in claim 1, is characterized in that... The hybrid power control unit is communicatively connected to the vehicle sensors and the driver's pedal. The hybrid power control unit receives signals from the vehicle sensors and the driver's pedal and calculates the total target power value of the vehicle.

4. The starting fuel injection control method for a hybrid electric vehicle that takes into account emissions, as described in claim 3, is characterized in that... The hybrid power control unit allocates the total target power value of the vehicle to the engine and the motor, and outputs the target power value of the engine and the required time of engine power output to the starting control unit.

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