Engine speed control method

Abstract

The invention provides an engine speed control method, and relates to the technical field of automobile electronic control, and the method comprises the following steps: determining a current first target idle speed of an engine of a vehicle according to a current driving condition of the vehicle; the current dynamic target idling speed of the engine is obtained, and the dynamic target idling speed is used for reducing the difference value between the current rotating speed of the engine and the first target idling speed; the dynamic first target idle speed is converted into first target torque of the engine according to the current whole vehicle rotational inertia of the vehicle, and the first target torque is ideal torque corresponding to the first target idle speed; according to the first target torque and the current effective torque of the engine, the current first target activation position of the engine is determined; and if the first target activation position is larger than a torque activation threshold value, the engine is controlled to conduct oil injection ignition so that the torque of the engine can be the idle speed open-loop torque, the torque activation threshold value is determined by the current gear of the gearbox, and the idle speed open-loop torque is obtained by the current dynamic target idle speed of the engine.

Description

Technical Field

[0001] This invention relates to the field of automotive electronic control technology, and in particular to a method for controlling engine speed. Background Technology

[0002] Idle speed control is a crucial aspect of engine control, directly impacting the dynamic process of restoring fuel supply to the engine and stabilizing it at the target speed after fuel cut-off. The core purpose of idling is to maintain the engine's output combustion torque to balance internal losses and external loads, ensuring continuous operation at the set speed. The quality of idle speed control has a decisive impact on the vehicle's NVH (noise, vibration, and harshness) performance and driving comfort; therefore, the control algorithm must comprehensively consider vehicle status parameters such as vehicle speed and gear position.

[0003] With the increasing popularity of hybrid vehicles, precise idle speed control is becoming increasingly important for improving vehicle power, fuel economy, emissions levels, and driving quality.

[0004] However, in the existing technology, both strategies that directly control the idle speed based on the engine combustion process and schemes that rely on the intervention of the transmission to control the engine to enter idle speed have the problem of insufficient idle speed control accuracy. Summary of the Invention

[0005] This invention provides a method for controlling engine speed, which solves the problem in related technologies that cannot accurately control the engine to enter idle speed.

[0006] In a first aspect, the present invention provides a method for controlling engine speed, the method comprising: The first target idle speed of the vehicle's engine is determined based on the vehicle's current driving conditions. Based on the first target idle speed and the current operating parameters of the engine, the current dynamic target idle speed of the engine is obtained, and the dynamic target idle speed is used to reduce the difference between the current speed of the engine and the first target idle speed. Based on the current rotational inertia of the vehicle, the first target idle speed is converted into the first target torque of the engine, and the first target torque is the ideal torque corresponding to the first target idle speed. Based on the first target torque and the current effective torque of the engine, determine the current first target activation position of the engine; If the first target activation bit is greater than the torque activation threshold, the engine is controlled to perform fuel injection and ignition so that the engine torque is the idle open-loop torque. The torque activation threshold is determined by the current gear of the transmission, and the idle open-loop torque is obtained from the current dynamic target idle speed of the engine.

[0007] Optionally, after controlling the engine torque to the idle open-loop torque, the method further includes: The second target idle speed of the engine is obtained based on the driving conditions of the vehicle at the first target time. The second target activation position of the engine is determined based on the second target idle speed at the first target time. If the second target activation position is less than the torque exit threshold, the engine torque is controlled to be the idle closed-loop torque so that the engine speed reaches the third target idle speed. The torque exit threshold is determined by the gear of the transmission at the first target time, and the third target idle speed is determined according to the driving conditions of the vehicle at the second target time.

[0008] Optionally, determining the current first target idle speed of the vehicle's engine based on the vehicle's current driving conditions includes: Obtain the current X first static idle speeds, where the X first static idle speeds are ideal idle speeds under multiple preset operating conditions; The first target idle speed is obtained by comparing the maximum value of the X first static idle speeds with the third static idle speed. The third static idle speed is obtained based on the current operating parameters of the engine, including the current engine coolant temperature.

[0009] Optionally, obtaining the current dynamic target idle speed of the engine based on the first target idle speed and the current operating parameters of the engine includes: Match the first weighting coefficient corresponding to the current engine coolant temperature within the preset database; Within the database, a second weighting coefficient corresponding to the current gear of the transmission is determined based on a first difference between the first target idle speed and the current engine speed. The current dynamic target idle speed of the engine is obtained based on the first weighting coefficient, the second weighting coefficient, and the first target idle speed.

[0010] Optionally, converting the first target idle speed into the first target torque of the engine based on the current vehicle rotational inertia includes: The dynamic target idle speed is converted into the first target torque based on the first speed gradient and the vehicle's moment of inertia, wherein the first speed gradient is determined by the first difference.

[0011] Optionally, determining the current first target activation position of the engine based on the first target torque and the current effective torque of the engine includes: The current first target activation position of the engine is determined based on the second difference between the first target torque and the current effective torque of the engine.

[0012] Optionally, after controlling the engine to perform fuel injection and ignition, the method further includes: After N ignition cycles, the torque of the engine is controlled to be the idle open-loop torque, which is used to control the rate of decrease in engine speed.

[0013] Optionally, the current operating parameters of the engine also include the current total engine torque loss; the method further includes: Within the database, a third weighting coefficient corresponding to the first difference is determined based on the third difference between the first target idle speed and the current dynamic target idle speed of the engine. The idle open-loop torque is determined based on the sum of the current total engine torque loss and the first target correction torque, wherein the first target correction torque is obtained from the first target torque and the third weighting coefficient.

[0014] Optionally, the method further includes: The closed-loop idle torque of the engine at the first target time is determined based on the fourth difference between the engine's dynamic target idle speed at the first target time and the engine's rotational speed at the first target time.

[0015] Secondly, embodiments of the present invention also provide a vehicle, the vehicle comprising: Vehicle body; A vehicle electronic control unit, disposed in the vehicle body, is used to perform the method as described in the first aspect.

[0016] According to the engine speed control method provided in this embodiment of the invention, the first target idle speed of the vehicle's engine is determined based on the vehicle's current driving conditions; the current dynamic target idle speed of the engine is obtained based on the first target idle speed and the engine's current operating parameters, the dynamic target idle speed being used to reduce the difference between the engine's current speed and the first target idle speed; the first target idle speed is converted into a first target torque of the engine based on the vehicle's current rotational inertia, the first target torque being the ideal torque corresponding to the first target idle speed; the first target activation position of the engine is determined based on the first target torque and the engine's current effective torque; if the first target activation position is greater than a torque activation threshold, the engine is controlled to perform fuel injection ignition so that the engine torque is the idle open-loop torque, the torque activation threshold being determined by the current gear of the transmission, and the idle open-loop torque being obtained from the engine's current dynamic target idle speed. By determining the first target idle speed based on the vehicle's current driving conditions and generating a dynamic target idle speed in conjunction with the engine's current operating parameters, the difference between the current speed and the first target idle speed is reduced. Furthermore, by precisely converting the dynamic target idle speed into the engine's first target torque, the speed change gradient is transformed into torque demand, making torque control more closely match actual load requirements. This allows for precise speed control based on torque changes, enabling the engine to re-inject fuel and engage in idle speed control at the optimal moment. Simultaneously, it ensures the engine speed smoothly matches the dynamic target idle speed, thus smoothly transitioning to the first target idle speed, avoiding the risk of stalling, ensuring driving safety, improving NVH and driving pleasure, and to some extent solving the problem of inaccurate engine idle speed control in related technologies. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 The flowchart of an engine speed control method provided by an embodiment of the present invention is shown; Figure 2 The present invention illustrates the structure of a vehicle according to an embodiment of the present invention; Figure 3 This invention illustrates the concept of an engine speed control method provided by an embodiment of the present invention; Figure 4 This invention illustrates a control logic for the rotational speed of a left-hand rotating engine, as provided in an embodiment of the invention. Figure 5The implementation effect of an engine speed control method provided by an embodiment of the present invention is shown; Figure 6 This illustration shows a reference diagram for setting a dynamic correction coefficient according to an embodiment of the present invention. Detailed Implementation

[0019] As described in the background section, idle speed control is a crucial aspect of engine control, and its performance directly affects the dynamic process of the engine resuming fuel supply and stabilizing at the target speed after fuel cut-off. The core purpose of idling is to maintain the engine's output combustion torque to balance internal losses and external loads, ensuring continuous operation at the set speed. The quality of idle speed control has a decisive impact on the vehicle's NVH (noise, vibration, and harshness) performance and driving comfort; therefore, the control algorithm must comprehensively consider vehicle status parameters such as vehicle speed and gear position. With the increasing popularity of hybrid vehicles, precise idle speed control is becoming increasingly important for improving vehicle power, fuel economy, emissions levels, and driving quality.

[0020] However, in the existing technology, both strategies that directly control the idle speed based on the engine combustion process and schemes that rely on the intervention of the transmission to control the engine to enter idle speed have the problem of insufficient idle speed control accuracy.

[0021] According to the engine speed control method provided in this invention, a first target idle speed is determined based on the vehicle's current driving conditions, and a dynamic target idle speed is generated by combining the engine's current operating parameters, reducing the difference between the current speed and the first target idle speed. Furthermore, the dynamic target idle speed is precisely converted into the engine's first target torque, transforming the speed change gradient into torque demand, making torque control more closely match actual load requirements. Consequently, the engine speed can be precisely controlled based on torque changes, allowing the engine to re-inject fuel and engage in idle speed control at the optimal time. Simultaneously, the engine speed can smoothly match the dynamic target idle speed, thus smoothly transitioning to the first target idle speed, avoiding the risk of stalling, ensuring driving safety, improving NVH and driving pleasure, and to a certain extent solving the problem of inaccurate engine idle speed control in related technologies.

[0022] The technical solution of the present invention and how the technical solution of the present invention solves the above-mentioned technical problems will be described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of the present invention will now be described with reference to the accompanying drawings.

[0023] Figure 1 The flowchart illustrates a method for controlling engine speed according to an embodiment of the present invention. For example... Figure 1 As shown, the engine speed control method provided in this embodiment of the invention includes steps 110 to 150.

[0024] Step 110: Determine the current first target idle speed of the vehicle's engine based on the vehicle's current driving conditions.

[0025] The engine speed control method provided in this invention can be executed by the Vehicle Electronic Control Unit (VECU) on the vehicle. The VECU can monitor the vehicle's current driving conditions in real time, and also monitor the engine's operating status and parameters. For example, the VECU can obtain the vehicle's current driving conditions through the Engine Management System (EMS) and determine the vehicle's current first target idle speed based on these conditions. The first target idle speed is an idle speed target determined based on the current driving conditions and / or engine operating status. In other words, the target idle speed can change with changes in driving conditions and / or engine operating status.

[0026] Step 120: Based on the first target idle speed and the current operating parameters of the engine, obtain the current dynamic target idle speed of the engine. The dynamic target idle speed is used to reduce the difference between the current speed of the engine and the first target idle speed.

[0027] In this embodiment of the invention, the EMS control system can also read the current operating parameters of the engine based on the real-time signal sampling period (the period length can be preset in advance), including but not limited to: the current engine speed, the current gear of the transmission, the current engine coolant temperature, the ignition cycle, and the current total torque loss of the engine. The vehicle electronic control unit can obtain the current dynamic target idle speed of the engine based on the first target idle speed and the current operating parameters of the engine, so as to better adjust the current engine speed. In addition, step 140 can be executed to convert the dynamic target idle speed into torque control, so as to control the engine more directly through torque.

[0028] In this embodiment of the invention, before executing step 140, it is also necessary to obtain the current vehicle rotational inertia. The vehicle electronic control unit can obtain the vehicle rotational inertia from other vehicle control units.

[0029] Step 130: Based on the current vehicle rotational inertia, the first target idle speed is converted into the first target torque of the engine, where the first target torque is the ideal torque corresponding to the first target idle speed.

[0030] In this embodiment of the invention, the first target torque can be the engine's equal power torque, which is the pre-controlled torque for the engine's current operating parameters.

[0031] Step 140: Determine the current first target activation position of the engine based on the first target torque and the current effective torque of the engine.

[0032] In this embodiment of the invention, the current first target activation position of the engine can be determined based on the difference between the first target torque and the current effective torque of the engine. For example, the first target activation position can be the difference between the first target torque and the current effective torque. To control the engine speed more accurately, the difference can also be processed by a coefficient according to the driving conditions. The first target activation position can indicate whether the engine is currently in or out of idle speed control.

[0033] Step 150: If the first target activation position is greater than the torque activation threshold, control the engine to perform fuel injection and ignition so that the torque of the engine is the idle open-loop torque. The torque activation threshold is determined by the current gear of the transmission.

[0034] In this embodiment of the invention, if the first target activation bit is greater than the torque activation threshold, it indicates that the engine can currently inject fuel and ignite, entering the idle speed control stage. This allows the engine torque to be controlled as the idle open-loop torque, which is the torque required for the engine to enter idle speed control. The torque activation threshold can be determined by the current gear of the transmission. For example, a pre-set function relationship or a pre-set corresponding table, such as Table 1 below, can be used to match the determined torque activation threshold based on the current gear of the transmission. It should be understood that when setting the torque activation threshold, the set values ​​corresponding to different transmission gears cannot overlap; otherwise, the control logic will not be valid.

[0035] Table 1. Correspondence between transmission gear and torque activation threshold T_Tmax

[0036] According to the engine speed control method provided in this invention, a first target idle speed is determined based on the vehicle's current driving conditions, and a dynamic target idle speed is generated by combining the engine's current operating parameters, reducing the difference between the current speed and the first target idle speed. Furthermore, the dynamic target idle speed is precisely converted into the engine's first target torque, transforming the speed change gradient into torque demand, making torque control more closely match actual load requirements. Consequently, the engine speed can be precisely controlled based on torque changes, allowing the engine to re-inject fuel and engage in idle speed control at the optimal time. Simultaneously, the engine speed can smoothly match the dynamic target idle speed, thus smoothly transitioning to the first target idle speed, avoiding the risk of stalling, ensuring driving safety, improving NVH and driving pleasure, and to a certain extent solving the problem of inaccurate engine idle speed control in related technologies.

[0037] In this embodiment of the invention, after controlling the engine torque to be the open-loop idle torque, a second target idle speed of the engine can be obtained based on the driving conditions of the vehicle at a first target time; a second target activation position of the engine at the first target time is determined based on the second target idle speed; if the second target activation position is less than the torque exit threshold, the engine torque is controlled to be the closed-loop idle torque so that the engine speed reaches a third target idle speed, the torque exit threshold is determined by the gear position of the transmission at the first target time, and the third target idle speed is determined based on the driving conditions of the vehicle at the second target time.

[0038] In this embodiment of the invention, the first target time can be any time after the engine torque reaches the open-loop idle torque. After the engine torque reaches the open-loop idle torque, the second target idle speed of the engine can be obtained again based on the vehicle's driving conditions at the first target time, and the method described in steps 110 to 150 above can be repeated to determine the second target torque and the open-loop idle torque of the first target time based on the second target idle speed. The difference between the second target torque and the effective engine torque at the first target time is then calculated to determine the second target activation position. If the second target activation position is less than the torque exit threshold, the engine torque can be controlled to be the closed-loop idle torque. During the process of obtaining the closed-loop idle torque at the first target time, the PID adjustment torque of the engine at the first target time can be determined based on the fourth difference between the dynamic target idle speed of the engine at the first target time and the engine speed at the first target time. Adding the PID adjustment torque of the engine at the first target time to the open-loop idle torque of the first target time yields the closed-loop idle torque of the engine at the first target time. The torque exit threshold can be determined by the gear position of the transmission at the first target time. The relationship between the torque exit threshold and the transmission gear can be referenced above regarding the relationship between the torque activation threshold and the transmission gear, as shown in Table 2 below. It is important to understand that when setting the torque exit threshold, the settings for different transmission gears cannot overlap; otherwise, the control logic will not be valid.

[0039] Table 2. Correspondence between gearbox gear and torque exit threshold T_Tmin

[0040] Accordingly, after the engine torque reaches the closed-loop idle torque, i.e., after the second target time has elapsed, the third target idle speed of the engine can be obtained based on the vehicle's driving conditions during the second target time. When the engine speed reaches the third target idle speed, the control of the engine speed is discontinued. Based on the dynamic target idle speed activation and / or discontinuation strategy set according to the equal power torque and torque activation and / or discontinuation thresholds for different transmission gears, the engine speed can smoothly match the dynamic target idle speed, allowing the engine speed to transition more smoothly from the second target time to the third target idle speed, thus mitigating the risk of stalling to some extent.

[0041] The step 110 provided in this embodiment of the invention determines the current first target idle speed of the vehicle's engine based on the vehicle's current driving conditions. One implementation may include the following processing: obtaining X current first static idle speeds, wherein the X first static idle speeds are ideal idle speeds under multiple preset operating conditions; comparing the maximum value of the X first static idle speeds with a third static idle speed to obtain the first target idle speed, wherein the third static idle speed is obtained based on the current operating parameters of the engine, including the current engine coolant temperature.

[0042] In this embodiment of the invention, the ideal idle speed under multiple preset operating conditions can be exemplified as: ideal idle speed calculated based on combustion mode, ideal idle speed calculated based on charcoal canister flushing, ideal idle speed calculated based on engine oil temperature, ideal idle speed calculated based on generator and battery losses, ideal idle speed based on cabin heating requirements, ideal idle speed calculated based on hybrid mode, ideal idle speed calculated based on transmission status, and ideal idle speed calculated based on starting conditions. Any one of the X first static idle speeds can be one or more of the aforementioned ideal idle speeds. That is, the average value of the ideal idle speeds under multiple preset operating conditions can be taken as a first static idle speed, or the ideal idle speed under each preset operating condition can be taken as the first static idle speed itself.

[0043] In this embodiment of the invention, the third static idle speed can be determined based on the current operating parameters of the engine. For example, the third static idle speed may include the ideal idle speed obtained based on the current engine coolant temperature, or it may include the ideal idle speed obtained based on the current gear position of the transmission. Accordingly, the third static idle speed can be the ideal idle speed obtained based on the current engine coolant temperature itself, or it can be the ideal idle speed obtained by averaging the operating parameters of multiple engines. The maximum value among X first static idle speeds is compared with the third static idle speed, and the maximum value is taken again as the first target idle speed. Alternatively, the average of the maximum value among X first static idle speeds and the maximum value among X third static idle speeds can be taken as the first target idle speed.

[0044] In this embodiment of the invention, in the process of obtaining the first target idle speed, not only the vehicle's driving conditions are considered, but also the operating parameters of the vehicle's engine are considered, which can make the first target idle speed more accurate.

[0045] The step 120 provided in this embodiment of the invention obtains the current dynamic target idle speed of the engine based on the first target idle speed and the current operating parameters of the engine. One implementation may include the following processing: matching a first weighting coefficient corresponding to the current engine coolant temperature in a preset database; determining a second weighting coefficient corresponding to the current gear of the transmission based on a first difference between the first target idle speed and the current engine speed in the database; and obtaining the current dynamic target idle speed of the engine based on the first weighting coefficient, the second weighting coefficient, and the first target idle speed.

[0046] In this embodiment of the invention, a first weighting coefficient T_F1 can be determined based on the current engine coolant temperature. Curve relationships can be directly stored in a preset database, or tables can be directly stored, such as Table 3 below. When the engine coolant temperature is low, due to the large load caused by frictional losses, the first weighting coefficient can be set smaller, allowing the dynamic target idle speed to gradually match the first target idle speed, thus controlling the engine speed more smoothly. When the engine coolant temperature is high, the load is smaller after the oil temperature rises, and the value of the first weighting coefficient can be set larger.

[0047] Table 3 shows the correspondence between engine coolant temperature and the first weighting coefficient T_F1.

[0048] Subsequently, based on the first difference between the first target idle speed and the current engine speed, the second weighting coefficient M_F1 corresponding to the current gear of the transmission is determined in the database. The first difference characterizes the difference between the current engine speed and the ideal idle speed (first target idle speed). The correspondence between the first difference and the second weighting coefficient M_F1 is shown in Table 4. Idle speed control is based on the difference between the current engine speed and the ideal idle speed (first target idle speed). If the difference is too large, the engine speed is adjusted. Idle speed control generally intervenes when the transmission is in gear 3 or below. 0 can represent the transmission being in N or P gear. Different coefficients can be set for different gears based on the difference between the engine speed and the first target speed (first difference). Table 4 below uses empirical value 2.3 as an example. It should be understood that this example is not a limitation; in actual practice, any value can be set.

[0049] Table 4 shows the correspondence between the first difference and the second weighting coefficient M_F1.

[0050] In this embodiment of the invention, after obtaining the first weighting coefficient and the second weighting coefficient, the dynamic correction coefficient K can be calculated based on T_F1*M_F1 / ignition cycle Te. The duration of the ignition cycle can be determined by the engine, and can be between 10ms and 12ms, or other values. The dynamic target idle speed NDT is then calculated using the following formula:

[0051] Where Te represents the ignition cycle. The first target idle speed is represented by NDT(n-1), and the previous dynamic target idle speed is represented by NDT(n-1).

[0052] The step 130 provided in this embodiment of the invention converts the first target idle speed into the first target torque of the engine based on the current vehicle rotational inertia. One implementation may include the following processing: converting the dynamic target idle speed into the first target torque based on the first speed gradient and the vehicle rotational inertia, wherein the first speed gradient is determined by the first difference.

[0053] In this embodiment of the invention, the first target torque can be the engine's constant power torque, and the first speed gradient can also be the constant power speed gradient. The constant power speed gradient is equal to the difference between the first target idle speed and the current engine speed (i.e., the first difference) multiplied by the dynamic correction coefficient K (see the description above). Then, according to the following formula for the correspondence between speed gradient and torque, the dynamic target idle speed can be converted into the first target torque based on the constant power speed gradient and the vehicle's moment of inertia.

[0054]

[0055] Where T1 represents the first target torque, Jv represents the vehicle's moment of inertia, N represents the rotational speed, and t represents time. This represents the rotational speed gradient (the constant power rotational speed gradient in this formula). The formula for calculating the vehicle's moment of inertia, Jv, is as follows:

[0056] Where Mv represents the vehicle mass, Je represents the engine moment of inertia, and V1000, the vehicle speed corresponding to every 1000 rpm of the engine, is a constant in each fixed gear. Accordingly, the current effective torque of the engine can be obtained using the following formula:

[0057] Where T2 represents the current effective torque, Jv represents the vehicle's moment of inertia, N represents the rotational speed, and t represents time. The engine speed gradient (in this formula, it is the engine speed gradient) is equal to the difference between the current engine speed and the engine speed at the previous moment, divided by the ignition cycle Te.

[0058] The step 140 provided in this embodiment of the invention determines the current first target activation position of the engine based on the first target torque and the current effective torque of the engine. One implementation may include the following processing: determining the current first target activation position of the engine based on the second difference between the first target torque and the current effective torque of the engine.

[0059] In this embodiment of the invention, the second difference between the first target torque and the engine's current effective torque can be used as the engine's current first target activation value. Alternatively, the difference between the first target torque and the engine's effective torque can be coefficient-processed and used as the engine's current first target activation value.

[0060] In this embodiment of the invention, after obtaining the first target activation position of the engine, if the first target activation position is greater than the torque activation threshold, the engine is controlled to re-inject fuel and ignite. At this time, the combustion torque intervenes in the wheel-end torque control. Since the output torque of the engine is not yet stable at the moment of re-injection and combustion, the torque of the engine is controlled to be the idle open-loop torque after a delay of several ignition cycles after the first target activation position is activated. The idle open-loop torque is used to control the rate of decrease of the engine speed.

[0061] In this embodiment of the invention, the idle open-loop torque can be calculated in the following way: a third weighting coefficient corresponding to the first difference is determined in the database based on the third difference between the first target idle speed and the current dynamic target idle speed of the engine; the idle open-loop torque is determined based on the sum of the current total torque loss of the engine and the first target correction torque in the current operating parameters of the engine, wherein the first target correction torque is obtained from the first target torque and the third weighting coefficient.

[0062] For example, based on the third difference between the first target idle speed and the current dynamic target idle speed of the engine, a third weighting coefficient M_F2 corresponding to the first difference is determined. Then, the third weighting coefficient is multiplied by the first target torque to obtain the first target corrected torque. Finally, the first target corrected torque is summed with the current total torque loss of the engine to obtain the idle open-loop torque.

[0063] In this embodiment of the invention, during the initial stage of idle activation, the engine torque is the open-loop idle torque, the purpose of which is to quickly suppress the downward trend of engine speed and make the engine speed closely match the dynamic target idle speed. When the engine speed change gradient stabilizes, the second target activation position is less than the torque exit threshold, and then closed-loop control is activated. The closed-loop idle torque of the engine at the first target time is determined based on the fourth difference between the dynamic target idle speed of the engine at the first target time and the engine speed at the first target time. For example, the PID adjustment torque is defined based on the third difference between the actual engine speed at the first target time and the dynamic target idle speed at the first target time. The open-loop idle torque of the engine at the first target time plus the PID adjustment torque is the closed-loop idle indication torque. At this time, it is necessary to calculate the PID adjustment torque of the spark circuit and the air circuit separately for dual-path control, and finally obtain the idle spark circuit demand torque and the idle air circuit demand torque, thereby controlling the engine combustion torque.

[0064] Figure 2 The diagram illustrates the structure of a vehicle according to an embodiment of the present invention. For example... Figure 2 As shown in the figure, an embodiment of the present invention illustrates a vehicle 200 comprising: Vehicle body 210; The vehicle electronic control unit 220 is disposed on the vehicle body and is used to perform the method described above.

[0065] To better understand the engine speed control method provided in the embodiments of the present invention, examples are given below. It should be understood that these examples are not intended to be limiting. Figure 3 This invention illustrates the concept of an engine speed control method provided by an embodiment of the present invention, such as... Figure 3 As shown, the engine speed control method provided in this embodiment of the invention includes steps S1 to S5.

[0066] Step S1: Determine the static idle speed target based on the engine operating mode and status, accessory operating status, transmission status, vehicle mode and operating conditions, external demand, and basic target idle speed.

[0067] Step S2: Determine the dynamic correction coefficient based on the engine coolant temperature, transmission gear, the difference between the static target and the current engine speed, and the ignition cycle. Further, determine the current dynamic target idle speed target based on the static target and the dynamic target at the previous moment.

[0068] Step S3: Determine the target speed gradient (first speed gradient) of the equal power based on the static idle speed target and the engine speed, and simultaneously take the difference between the first speed gradient and the engine speed gradient. Calculate the difference torque (first target activation position or second target activation position) through the relationship between the vehicle's rotational inertia. Determine whether to dynamically activate the target speed by comparing this torque with the activation and deactivation thresholds.

[0069] Step S4: Determine the total speed open-loop indicated torque based on the target speed gradient (first speed gradient), weighting coefficient, vehicle rotational inertia, and total engine torque loss.

[0070] Step S5: Determine the idle closed-loop fire circuit indication torque and the idle closed-loop air circuit indication torque based on the PID adjustment torque of the fire circuit and the PID adjustment torque of the air circuit, respectively.

[0071] Figure 4 This invention illustrates an engine speed control logic provided by an embodiment of the present invention. The following is a description of this logic in conjunction with... Figure 4 ,explain Figure 3 This demonstrates a method for controlling engine speed.

[0072] In step S1, the current first target idle speed is determined based on the vehicle's driving conditions and engine operating status. Then, according to the description in step S2, ... Figure 4 The logic described at the top, combined with the first and second weighting coefficients, yields the dynamic correction coefficients, and subsequently, the dynamic target idle speed corresponding to the first target idle speed is obtained. In step S3, as... Figure 4 The middle section describes a process where the first speed gradient (equal power target speed gradient) is determined based on the first difference between the first target idle speed and the current engine speed. The gradient difference between the first speed gradient and the engine speed gradient is first calculated using the relationship between the vehicle's moment of inertia and the gradient difference. This first target activation position is then compared with the torque activation threshold. (It should be explained that the method described in step S3 is consistent with the method described above, which uses the difference between the first target torque and the current actual effective torque as the first target activation position, because the torque can be obtained by multiplying the speed gradient and the vehicle's moment of inertia.) When the first target activation position is greater than or equal to the torque activation threshold T_Tmax, S is set to 1, Q is set to 1, dynamic target control is activated, the engine is re-injected, and after several ignition cycles, the engine speed is controlled to the idle open-loop torque described in step S4. When the first target activation position is less than or equal to the torque threshold T_Tmin, R is set to 1, Q is set to 0, dynamic target control is exited, and the engine speed is controlled to the idle closed-loop torque described in step S5. The idle open-loop torque can be calculated as follows: Figure 4 As shown in the lower part, based on the third difference between the first target idle speed and the dynamic target idle speed, the third weighting coefficient corresponding to the first difference is obtained. The third weighting coefficient is then combined with the first speed gradient and the current vehicle rotational inertia to obtain the first target correction torque, thereby further obtaining the idle speed open-loop torque.

[0073] Figure 5 The implementation effect of an engine speed control method provided by an embodiment of the present invention is shown. For example... Figure 5 As shown, at the vertical line on the time axis, corresponding to the moment of the first target activation, the engine restarts fuel injection and ignition. After N ignition cycles, the engine torque is controlled to be the idle open-loop torque. At the first target time, if the second target activation point corresponding to the first target time is less than the torque exit threshold, the engine torque is controlled to be the idle closed-loop torque. Subsequently, at the second target time, the engine speed reaches the third target idle speed. During the control of engine speed, the first target correction torque can be used to adjust the idle open-loop torque and / or the idle closed-loop torque, making the engine speed approach the third target idle speed at the second target time.

[0074] Additionally, in the engine speed control method provided in the embodiments of the present invention, Figure 6 This illustration shows a reference diagram for setting a dynamic correction coefficient according to an embodiment of the present invention. Figure 6 The static target in the calculation is the first target idle speed. If the dynamic correction coefficient K is set too large (that is, the first weighting coefficient and / or the second weighting coefficient are set too large), the engine speed will drop too quickly, which may lead to momentary vibration or even stalling. If the dynamic correction coefficient K is set too small, the engine speed will remain too high and will not be able to reach the static target, which may lead to higher fuel consumption and emissions, as well as high-speed engine noise.

[0075] In an exemplary embodiment, a non-transitory computer-readable storage medium including instructions is also provided, such as a memory including instructions that can be executed by a processor of a device to perform the described method. For example, the non-transitory computer-readable storage medium may be a ROM, random access memory (RAM), CD-ROM, magnetic tape, floppy disk, and optical data storage device, etc. This non-transitory computer-readable storage medium, when the instructions in the storage medium are executed by a processor of an electronic device, enables the electronic device to perform... Figure 1 The method shown.

[0076] This application also provides a computer program product, including a computer program, which, when executed by a processor, performs... Figure 1 The method shown.

[0077] The above description does not provide detailed technical specifications regarding the structure of each layer. However, those skilled in the art should understand that layers and regions of desired shapes can be formed using various technical means. Furthermore, to form the same structure, those skilled in the art can also design methods that are not entirely identical to those described above. Additionally, although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be advantageously combined.

[0078] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0079] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for controlling engine speed, characterized in that, The method comprises: The first target idle speed of the vehicle's engine is determined based on the vehicle's current driving conditions. Based on the first target idle speed and the current operating parameters of the engine, the current dynamic target idle speed of the engine is obtained, and the dynamic target idle speed is used to reduce the difference between the current speed of the engine and the first target idle speed. Based on the current rotational inertia of the vehicle, the first target idle speed is converted into the first target torque of the engine, and the first target torque is the ideal torque corresponding to the first target idle speed. Based on the first target torque and the current effective torque of the engine, determine the current first target activation position of the engine; If the first target activation bit is greater than the torque activation threshold, the engine is controlled to perform fuel injection and ignition so that the engine torque is the idle open-loop torque. The torque activation threshold is determined by the current gear of the transmission, and the idle open-loop torque is obtained from the current dynamic target idle speed of the engine.

2. The method according to claim 1, characterized in that, After controlling the engine torque to the idle open-loop torque, the method further includes: The second target idle speed of the engine is obtained based on the driving conditions of the vehicle at the first target time. The second target activation position of the engine is determined based on the second target idle speed at the first target time. If the second target activation position is less than the torque exit threshold, the engine torque is controlled to be the idle closed-loop torque so that the engine speed reaches the third target idle speed. The torque exit threshold is determined by the gear of the transmission at the first target time, and the third target idle speed is determined according to the driving conditions of the vehicle at the second target time.

3. The method according to claim 1, characterized in that, Determining the current first target idle speed of the vehicle's engine based on the vehicle's current driving conditions includes: Obtain the current X first static idle speeds, where the X first static idle speeds are ideal idle speeds under multiple preset operating conditions; The first target idle speed is obtained by comparing the maximum value of the X first static idle speeds with the third static idle speed. The third static idle speed is obtained based on the current operating parameters of the engine, including the current engine coolant temperature.

4. The method according to claim 3, characterized in that, The step of obtaining the current dynamic target idle speed of the engine based on the first target idle speed and the current operating parameters of the engine includes: Match the first weighting coefficient corresponding to the current engine coolant temperature within the preset database; Within the database, a second weighting coefficient corresponding to the current gear of the transmission is determined based on a first difference between the first target idle speed and the current engine speed. The current dynamic target idle speed of the engine is obtained based on the first weighting coefficient, the second weighting coefficient, and the first target idle speed.

5. The method according to claim 4, characterized in that, The step of converting the first target idle speed into the first target torque of the engine based on the current vehicle rotational inertia includes: converting the dynamic target idle speed into the first target torque based on the first speed gradient and the vehicle rotational inertia, wherein the first speed gradient is determined by the first difference.

6. The method according to claim 5, characterized in that, Determining the current first target activation position of the engine based on the first target torque and the current effective torque of the engine includes: The current first target activation position of the engine is determined based on the second difference between the first target torque and the current effective torque of the engine.

7. The method according to claim 6, characterized in that, After controlling the engine to perform fuel injection and ignition, the method further includes: After N ignition cycles, the torque of the engine is controlled to be the idle open-loop torque, which is used to control the rate of decrease in engine speed.

8. The method according to claim 7, characterized in that, The engine's current operating parameters also include the current total engine torque loss; The method further includes: Within the database, a third weighting coefficient corresponding to the first difference is determined based on the third difference between the first target idle speed and the current dynamic target idle speed of the engine. The idle open-loop torque is determined based on the sum of the current total engine torque loss and the first target correction torque, wherein the first target correction torque is obtained from the first target torque and the third weighting coefficient.

9. The method according to claim 2, characterized in that, The method further includes: The closed-loop idle torque of the engine at the first target time is determined based on the fourth difference between the engine's dynamic target idle speed at the first target time and the engine's rotational speed at the first target time.

10. A vehicle, characterized in that, The vehicles include: Vehicle body; A vehicle electronic control unit, disposed on the vehicle body, is used to perform the method as described in any one of claims 1-9.

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