Method for improving vehicle overtaking acceleration dynamics and vehicle

Abstract

The present application discloses a method for improving vehicle overtaking acceleration dynamics and a vehicle. The method comprises: determining that the vehicle is in an overtaking acceleration state; when the temperature of the exhaust gas before the particulate filter (DPF) is less than a first exhaust temperature setting value, applying a first smoke density limit; when the temperature of the exhaust gas before the DPF is greater than or equal to the first exhaust temperature setting value, applying a second smoke density limit; wherein the second smoke density limit is less restrictive than the first smoke density limit. When the temperature of the exhaust gas before the DPF is low, the chemical reaction rate of the soot in the DPF is slow, and a larger smoke density limit is required. When the temperature of the exhaust gas before the DPF reaches an appropriate temperature, the chemical reaction rate of the soot in the DPF is fast, which can quickly reduce the soot. At this time, the diesel engine can be allowed to produce more soot, reducing the smoke density limit and increasing the instantaneous fuel injection volume, thereby improving the vehicle's overtaking acceleration dynamics.

Description

Technical Field

[0001] The present application relates to the field of vehicle control technology, and in particular to a method for improving vehicle overtaking acceleration dynamics and a vehicle. Background Art

[0002] During vehicle operation, transient operating conditions account for a significant portion of the vehicle's time. Therefore, the transient performance of a diesel engine significantly impacts vehicle performance. Due to the intake lag characteristic of the turbocharger, the diesel engine's intake velocity cannot keep pace with the injection velocity, resulting in high soot emissions under transient conditions. To reduce vehicle soot emissions, smoke limiting is often employed. This limits the maximum injection volume based on the current intake volume and engine speed. This primarily addresses issues during acceleration or loading where the intake velocity cannot keep up with changes in fuel volume, leading to a decrease in the excess air coefficient, incomplete combustion, black smoke emission from the engine, and substandard emissions.

[0003] Power is a fundamental and important aspect of a vehicle's performance. Overrun acceleration refers to the process of accelerating a vehicle from a certain speed to a certain maximum speed in either top or second-highest gear. The shorter the acceleration time, the better the overrun performance. However, during overrun acceleration, to ensure transient soot emissions, the fuel injection volume is reduced due to smoke density limitations, resulting in a decrease in power under transient conditions. Summary of the Invention

[0004] In view of this, the present application provides a method and a vehicle for improving the overtaking acceleration power of a vehicle, which can improve the vehicle's power during overtaking acceleration while ensuring that carbon smoke emissions meet requirements.

[0005] To solve the above problems, the technical solutions provided by this application are as follows:

[0006] The present application provides a method for improving vehicle overtaking acceleration dynamics, the method comprising:

[0007] Determining that the vehicle is in an overtaking and accelerating state;

[0008] When the exhaust temperature before the particulate filter DPF is less than the first exhaust temperature setting value, the first smoke density limit is adopted;

[0009] When the exhaust temperature before the DPF is greater than or equal to the first exhaust temperature setting value, the second smoke density limit is adopted; the restriction degree of the second smoke density limit is less than the restriction degree of the first smoke density limit.

[0010] Preferably, the method further comprises:

[0011] When the exhaust temperature before the DPF is greater than or equal to the first exhaust temperature setting value and less than the second exhaust temperature setting value, the second smoke density limit is adopted; the second exhaust temperature setting value is greater than the first exhaust temperature setting value;

[0012] When the exhaust temperature before the DPF is greater than or equal to the second exhaust temperature setting value, the third smoke density limit is adopted; the restriction degree of the third smoke density limit is less than the restriction degree of the second smoke density limit.

[0013] Optionally, determining that the vehicle is in the overtaking acceleration state includes:

[0014] It is determined that the engine speed reaches a preset range, the throttle change rate is greater than or equal to a preset change rate, and the vehicle speed is greater than or equal to a preset speed.

[0015] Preferably, the first exhaust temperature setting value is 280°C to 320°C.

[0016] Preferably, the second exhaust temperature setting value is 480°C to 520°C.

[0017] The present application also provides a vehicle with improved overtaking acceleration power, comprising: an electronic control unit ECU, a particulate filter DPF, and a temperature sensor;

[0018] DPF, used to carry out chemical reactions of soot and reduce soot;

[0019] Temperature sensor, used to obtain DPF front exhaust temperature;

[0020] The ECU is used to determine whether the vehicle is in an overtaking acceleration state. When the DPF front exhaust temperature is less than the first exhaust temperature setting value, the first smoke density limit is adopted; when the DPF front exhaust temperature is greater than or equal to the first exhaust temperature setting value, the second smoke density limit is adopted; the degree of restriction of the second smoke density limit is less than that of the first smoke density limit.

[0021] Preferably, the ECU is further configured to, when the exhaust temperature before the DPF is greater than or equal to a first exhaust temperature setting value and less than a second exhaust temperature setting value, adopt a second smoke density limit; and the second exhaust temperature setting value is greater than the first exhaust temperature setting value;

[0022] When the exhaust temperature before the DPF is greater than or equal to the second exhaust temperature setting value, the third smoke density limit is adopted; the restriction degree of the third smoke density limit is less than the restriction degree of the second smoke density limit.

[0023] Optionally, the ECU is specifically configured to determine whether the engine speed reaches a preset range, whether the throttle change rate is greater than or equal to a preset change rate, and whether the vehicle speed is greater than or equal to a preset speed.

[0024] Preferably, the first exhaust temperature setting value is 280°C to 320°C.

[0025] Preferably, the second exhaust temperature setting value is 480°C to 520°C.

[0026] It can be seen that this application has the following beneficial effects:

[0027] The present application provides a method for improving vehicle overtaking acceleration performance. When the vehicle is in overtaking acceleration, the DPF front exhaust temperature is segmented. When the DPF front exhaust temperature is less than a first exhaust temperature setting value, a first smoke density limit is applied; when the DPF front exhaust temperature is greater than or equal to the first exhaust temperature setting value, a second smoke density limit is applied. The second smoke density limit is less restrictive than the first smoke density limit. When the DPF front exhaust temperature is low, the chemical reaction rate of soot in the DPF is slow, requiring a higher smoke density limit. When the DPF front exhaust temperature reaches an appropriate temperature, the chemical reaction rate of soot in the DPF is faster, enabling rapid soot reduction. This allows the diesel engine to produce more soot, reducing the smoke density limit and increasing the instantaneous fuel injection volume, thereby improving the vehicle's overtaking acceleration performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A schematic diagram of a process in which a vehicle exceeds a smoke limit during acceleration;

[0029] Figure 2 A schematic diagram of the chemical reaction characteristics of soot;

[0030] Figure 3 A flow chart of a method for improving vehicle overtaking acceleration dynamics provided in an embodiment of the present application;

[0031] Figure 4 A flowchart of another method for improving vehicle overtaking acceleration dynamics provided in an embodiment of the present application;

[0032] Figure 5 A schematic diagram of a vehicle with improved overtaking acceleration power provided in an embodiment of the present application. DETAILED DESCRIPTION

[0033] In order to more clearly understand the various embodiments of the present application, the process of a vehicle exceeding the smoke limit during acceleration is briefly described below.

[0034] See also Figure 1 , which is a schematic diagram of the process of a vehicle exceeding the smoke limit during acceleration.

[0035] A sudden increase in the throttle opening indicates that the vehicle has entered the overtaking acceleration state; the theoretical fuel injection quantity is the fuel injection quantity in the overtaking acceleration state when the vehicle is not restricted by smoke density; the smoke limit fuel quantity is the fuel injection quantity in the overtaking acceleration state after the vehicle is restricted by smoke density; the smoke limit duration refers to the time when the fuel injection quantity rises to the smoke limit fuel quantity in the overtaking acceleration state.

[0036] After adopting smoke limitation, the smoke limitation fuel quantity is significantly lower than the theoretical fuel injection quantity; as the fuel injection quantity decreases, the time required for the vehicle to accelerate to a certain high speed increases, the overtaking acceleration performance decreases, and the power decreases.

[0037] The technical solution provided in the embodiment of the present application makes full use of the carbon soot chemical reaction characteristics of the vehicle. When the vehicle is overtaking and accelerating, the exhaust temperature in front of the particulate filter DPF is segmented, and different smoke density limits are used at different exhaust temperatures in front of the DPF to control the injection amount differently. This can improve the vehicle's power during overtaking and acceleration while ensuring that carbon soot emissions meet the requirements.

[0038] In order to enable those skilled in the art to better understand and implement the technical solution of the present application, the working principle of the DPF is described below with reference to the accompanying drawings.

[0039] Installed in the exhaust system of a diesel vehicle, the DPF (Digital Particulate Filter) filters and reduces particulate matter in exhaust gases. Soot particles deposited during DPF operation gradually increase exhaust resistance, deteriorating engine performance. Therefore, the DPF needs to be promptly cleaned of soot, a process known as regeneration. DPF regeneration can be performed passively or actively.

[0040] See also Figure 2 , which is a schematic diagram of the chemical reaction characteristics of soot.

[0041] When the exhaust temperature is relatively low, the soot in the DPF primarily reacts with NO2 in the exhaust, which oxidizes the soot into CO2, thereby reducing soot. This process is called passive regeneration, and the rate of passive regeneration accelerates as the temperature rises. When the exhaust temperature is high, the soot in the DPF primarily reacts with O2, which oxidizes the soot into CO2, also reducing soot. This process is called active regeneration.

[0042] Since O2 is more oxidizing than NO2 and the reaction temperature of the active regeneration process is higher, the chemical reaction rate of the soot in the active regeneration process is faster and the efficiency of reducing soot is higher.

[0043] The technical solutions provided in the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0044] See also Figure 3 , which is a flow chart of a method for improving vehicle overtaking acceleration dynamics provided in an embodiment of the present application.

[0045] The method includes:

[0046] S301: Determine whether the vehicle is in an overtaking acceleration state. If so, execute step S302.

[0047] This application does not specifically limit the specific criteria for determining whether the vehicle is in an over-acceleration driving state. For example, the engine speed may reach a preset range, the throttle change rate may be greater than or equal to a preset change rate, and the vehicle speed may be greater than or equal to a preset speed.

[0048] If the engine speed reaches the preset range, it indicates that the engine speed meets the requirements for overtaking acceleration and is within the speed range constrained by the smoke limit. If the throttle change rate is greater than or equal to the preset rate, it indicates that the throttle opening has changed rapidly, indicating that the vehicle is accelerating. If the vehicle speed is greater than or equal to the preset speed, it indicates that the vehicle speed has reached the speed requirement before overtaking acceleration. The judgment can be made based on these three conditions for greater accuracy. Alternatively, the speed or throttle change rate can be omitted, but the accuracy of the overtaking acceleration judgment will be reduced. Of course, other criteria can also be used for judgment.

[0049] S302: Determine whether the exhaust temperature before the DPF is less than the first exhaust temperature setting value. If so, execute step S303; otherwise, execute step S304.

[0050] The present application does not specifically limit the value of the first exhaust temperature setting. According to the chemical reaction characteristics of soot, the first exhaust temperature setting value may be 280° C. to 320° C., preferably 300° C.; other values ​​may also be used.

[0051] S303: adopting the first smoke density limit.

[0052] S304: Adopt the second smoke density limit.

[0053] The second smoke density limit has a lower degree of restriction than the first smoke density limit. A higher degree of restriction indicates that less soot is allowed to be generated and the maximum fuel injection amount is smaller; a lower degree of restriction indicates that more soot is allowed to be generated and the maximum fuel injection amount is larger.

[0054] The DPF front exhaust temperature is lower than the first exhaust temperature setting value, indicating that the soot chemical reaction rate in the DPF is slow and the soot reduction efficiency is low. Therefore, it is necessary to adopt a more restrictive first smoke limit to reduce the fuel injection amount to reduce soot emissions.

[0055] The DPF front exhaust temperature is greater than or equal to the first exhaust temperature setting value, which means that the soot chemical reaction rate in the DPF is faster and the soot reduction efficiency is high. Therefore, the second smoke limit with a smaller degree of restriction can be used to appropriately increase the fuel injection amount to increase the vehicle's power during overtaking acceleration; the increase in soot caused by the increase in fuel injection amount is consumed by the soot chemical reaction in the DPF.

[0056] The present application provides a method for improving vehicle overtaking acceleration performance. When the vehicle is in overtaking acceleration, the DPF front exhaust temperature is segmented. When the DPF front exhaust temperature is less than a first exhaust temperature setting value, a first smoke density limit is applied; when the DPF front exhaust temperature is greater than or equal to the first exhaust temperature setting value, a second smoke density limit is applied. The second smoke density limit is less restrictive than the first smoke density limit. When the DPF front exhaust temperature is low, the chemical reaction rate of soot in the DPF is slow, requiring a higher smoke density limit. When the DPF front exhaust temperature reaches an appropriate temperature, the chemical reaction rate of soot in the DPF is faster, enabling rapid soot reduction. This allows the diesel engine to produce more soot, reducing the smoke density limit and increasing the instantaneous fuel injection volume, thereby improving the vehicle's overtaking acceleration performance.

[0057] This application does not limit the degree of restriction by grading and classification. The above is only introduced with two levels as an example. It can also be divided into more levels for more refined control. The following is a detailed introduction with reference to the accompanying drawings.

[0058] See also Figure 4 , this figure is a flow chart of another method for improving vehicle overtaking acceleration dynamics provided in an embodiment of the present application.

[0059] The method includes:

[0060] S401: Determine whether the vehicle is in an overtaking acceleration state. If so, execute step S402.

[0061] S402: Determine whether the DPF front exhaust temperature is less than the first exhaust temperature setting value. If so, execute step S403; otherwise, execute step S404.

[0062] S403: adopting the first smoke density limit.

[0063] S404: Determine whether the exhaust temperature before the DPF is less than the second exhaust temperature setting value. If so, execute step S405; otherwise, execute step S406.

[0064] The second exhaust temperature setting value represents the approximate critical temperature of the DPF active regeneration process; the present application does not specifically limit the specific size of the second exhaust temperature setting value. According to the chemical reaction characteristics of soot, the second exhaust temperature setting value can be 480°C to 520°C, preferably, 500°C; other values ​​can also be taken.

[0065] S405: Adopt the second smoke density limit.

[0066] S406: Adopt the third smoke density limit.

[0067] The degree of restriction of the third smoke density limit is smaller than that of the second smoke density limit.

[0068] The DPF front exhaust temperature is greater than or equal to the first exhaust temperature setting value and less than the second exhaust temperature setting value, which means that the regeneration process in the DPF is mainly passive regeneration, and the passive regeneration speed is faster. Therefore, the second smoke limit with a less restrictive degree can be used, and the fuel injection amount can be appropriately increased to increase the vehicle's power during overtaking acceleration.

[0069] The DPF front exhaust temperature is greater than or equal to the second exhaust temperature setting value, which means that the regeneration process in the DPF is mainly active regeneration. Since the oxidizing property of O2 is stronger than that of NO2 and the reaction temperature of the active regeneration process is higher, the reaction speed of active regeneration is faster than that of passive regeneration. Therefore, the third smoke limit with a smaller degree of restriction can be used to continue to increase the fuel injection amount to further increase the vehicle's power during overtaking acceleration.

[0070] The method for improving vehicle overtaking acceleration dynamics provided in the embodiment of the present application can also divide the DPF front exhaust temperature into three sections. When the DPF front exhaust temperature is greater than or equal to the first exhaust temperature setting value and less than the second exhaust temperature setting value, it indicates that the DPF is performing rapid passive regeneration and the second smoke density limit is adopted; when the DPF front exhaust temperature is greater than or equal to the second exhaust temperature setting value, it indicates that the DPF is performing faster active regeneration and the carbon soot consumption rate is faster. A third smoke density limit with a smaller degree of restriction is adopted to further increase the fuel injection amount and further increase the vehicle's overtaking acceleration dynamics.

[0071] Based on the method for improving vehicle overtaking acceleration dynamics provided in the above embodiments, the embodiments of the present application also provide a vehicle with improved vehicle overtaking acceleration dynamics, which is described in detail below with reference to the accompanying drawings.

[0072] See also Figure 5 , this figure is a schematic diagram of a vehicle with improved overtaking acceleration power provided by an embodiment of the present application.

[0073] The vehicle 1000 with improved overtaking acceleration power provided in the present application includes: an electronic control unit ECU 100 , a particulate filter DPF 200 and a temperature sensor 300 .

[0074] DPF200 is used to carry out chemical reaction of soot and reduce soot.

[0075] The temperature sensor 300 is used to obtain the exhaust temperature before the DPF 200.

[0076] ECU 100 is configured to, when the vehicle is in an overrunning acceleration state and the exhaust temperature before DPF 200 is less than a first exhaust temperature setting value, apply a first smoke density limit; and when the exhaust temperature before DPF 200 is greater than or equal to the first exhaust temperature setting value, apply a second smoke density limit; the second smoke density limit having a less restrictive degree than the first smoke density limit. A greater smoke density limit indicates less soot generation and a smaller maximum fuel injection amount; a smaller smoke density limit indicates more soot generation and a larger maximum fuel injection amount.

[0077] Among them, ECU100 can be specifically used to determine whether the engine speed reaches a preset range, whether the throttle change rate is greater than or equal to the preset change rate, and whether the vehicle speed is greater than or equal to the preset speed, to determine whether the vehicle is in an overtaking acceleration state; ECU100 can also make judgments based on other standards.

[0078] The present application does not specifically limit the value of the first exhaust temperature setting. According to the chemical reaction characteristics of soot, the first exhaust temperature setting value may be 280° C. to 320° C., preferably 300° C.; other values ​​may also be used.

[0079] The ECU 100 may also be configured to adopt a second smoke density limit when the exhaust temperature before the DPF is greater than or equal to a first exhaust temperature setting value and less than a second exhaust temperature setting value; the second exhaust temperature setting value is greater than the first exhaust temperature setting value.

[0080] When the DPF front exhaust temperature is greater than or equal to the second exhaust temperature setting value, the third smoke density limit is adopted; the restriction degree of the third smoke density limit is less than the restriction degree of the second smoke density limit.

[0081] The present application does not specifically limit the specific size of the second exhaust temperature setting value. According to the chemical reaction characteristics of soot, the second exhaust temperature setting value may be 480° C. to 520° C., preferably 500° C.; other values ​​may also be used.

[0082] In a vehicle with improved overtaking acceleration performance provided by an embodiment of the present application, when the ECU determines that the vehicle is in an overtaking acceleration state, the DPF front exhaust temperature is segmented. When the DPF front exhaust temperature is less than a first exhaust temperature setting value, a first smoke density limit is applied; when the DPF front exhaust temperature is greater than or equal to the first exhaust temperature setting value, a second smoke density limit is applied; wherein the second smoke density limit is less restrictive than the first smoke density limit. When the DPF front exhaust temperature is low, the chemical reaction rate of the soot in the DPF is slow, requiring a higher smoke density limit. When the DPF front exhaust temperature reaches an appropriate temperature, the chemical reaction rate of the soot in the DPF is faster, enabling rapid soot reduction. At this time, the diesel engine can produce more soot, reducing the smoke density limit and increasing the instantaneous fuel injection volume, thereby improving the vehicle's overtaking acceleration performance.

[0083] In addition, the embodiment of the present application provides a vehicle with improved overtaking acceleration power. The ECU can also segment the DPF front exhaust temperature into more levels when the vehicle is in the overtaking acceleration state. When the DPF front exhaust temperature is greater than or equal to the second exhaust temperature setting value, a third smoke limit with a smaller degree of restriction is adopted to further increase the fuel injection amount, thereby further increasing the vehicle's overtaking acceleration power.

[0084] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Reference can be made to the common and similar parts between the various embodiments. For the systems or devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method description.

[0085] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present application. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for improving vehicle overtaking acceleration dynamics, characterized in that: The method includes: Determining that the vehicle is in an overtaking and accelerating state; When the exhaust temperature before the particulate filter DPF is less than the first exhaust temperature setting value, the first smoke density limit is adopted; When the exhaust temperature before the DPF is greater than or equal to the first exhaust temperature setting value, a second smoke density limit is adopted; the restriction degree of the second smoke density limit is less than the restriction degree of the first smoke density limit; the engine fuel injection amount when the second smoke density limit is adopted is greater than the engine fuel injection amount when the first smoke density limit is adopted; The determining that the vehicle is in the overtaking acceleration state includes: It is determined that the engine speed reaches a preset range, the throttle change rate is greater than or equal to a preset change rate, and the vehicle speed is greater than or equal to a preset speed, and the preset range is within a speed range constrained by the smoke density limit.

2. The method according to claim 1, characterized in that Also includes: When the exhaust temperature before the DPF is greater than or equal to the first exhaust temperature setting value and less than the second exhaust temperature setting value, the second smoke density limit is adopted; and the second exhaust temperature setting value is greater than the first exhaust temperature setting value; When the DPF pre-exhaust temperature is greater than or equal to the second exhaust temperature setting value, a third smoke density limit is adopted; and the degree of restriction of the third smoke density limit is less than the degree of restriction of the second smoke density limit.

3. The method according to claim 1, characterized in that The first exhaust temperature setting value is 280°C to 320°C.

4. The method according to claim 2, characterized in that The second row temperature setting value is 480℃~520℃.

5. A vehicle with improved overtaking acceleration performance, characterized in that: include: Electronic control unit ECU, particulate filter DPF and temperature sensor; The DPF is used to carry out a chemical reaction of soot to reduce soot; The temperature sensor is used to obtain the DPF front exhaust temperature; The ECU is configured to determine that the vehicle is in an overtaking acceleration state, and when the DPF front exhaust temperature is less than a first exhaust temperature setting value, adopt a first smoke density limit; when the DPF front exhaust temperature is greater than or equal to the first exhaust temperature setting value, adopt a second smoke density limit; the restriction level of the second smoke density limit is less than the restriction level of the first smoke density limit; and the engine fuel injection amount when the second smoke density limit is adopted is greater than the engine fuel injection amount when the first smoke density limit is adopted; The ECU is used to determine whether the vehicle is in the overtaking acceleration state and includes: It is determined that the engine speed reaches a preset range, the throttle change rate is greater than or equal to a preset change rate, and the vehicle speed is greater than or equal to a preset speed, and the preset range is within a speed range constrained by the smoke density limit.

6. The vehicle according to claim 5, characterized in that The ECU is further configured to adopt a second smoke density limit when the exhaust temperature before the DPF is greater than or equal to the first exhaust temperature setting value and less than a second exhaust temperature setting value; and the second exhaust temperature setting value is greater than the first exhaust temperature setting value; When the DPF pre-exhaust temperature is greater than or equal to the second exhaust temperature setting value, a third smoke density limit is adopted; and the degree of restriction of the third smoke density limit is less than the degree of restriction of the second smoke density limit.

7. The vehicle according to claim 5, characterized in that The first exhaust temperature setting value is 280°C to 320°C.

8. The vehicle according to claim 6, characterized in that The second row temperature setting value is 480℃~520℃.

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