Shift control methods, devices and hybrid vehicles

Abstract

This application discloses a shift control method applied to a hybrid vehicle. The hybrid vehicle's transmission includes a first clutch and a second clutch, where the first clutch is the clutch to be disengaged and the second clutch is the clutch to be engaged. The method includes: determining the inertial torque generated by the input shaft of the transmission after a shift based on a first transmission ratio and a second transmission ratio, wherein the first transmission ratio is the transmission ratio of the gear set corresponding to the first clutch, and the second transmission ratio is the transmission ratio of the gear set corresponding to the second clutch; and adjusting the torque of the input shaft based on the inertial torque during the shift. The shift control method, device, and hybrid vehicle disclosed in this application can utilize the fast and precise torque response characteristics of the electric motor, combined with the control of the dual clutch, to counteract the influence of inertial torque during the shift, maintain power transmission, and thereby improve the smoothness and power performance of the shift process.

Description

Technical Field

[0001] This application relates to the field of vehicle control technology, specifically to a shift control method, device, and hybrid vehicle. Background Technology

[0002] In recent years, with the increasing awareness of environmental protection, the development of hybrid vehicles has received more and more attention. The efficient transmission system of hybrid vehicles can significantly improve the vehicle's power and fuel economy, achieving energy conservation, emission reduction, and reduced environmental pollution.

[0003] Most hybrid power systems in related technologies are developed based on traditional automatic transmissions. They integrate an electric motor into the front or rear of transmissions such as AT (Automatic Transmission), AMT (Automated Manual Transmission), CVT (Continuously Variable Transmission), or DCT (Dual-clutch Transmission) to form a hybrid system. The shift control mode of these hybrid systems based on traditional automatic transmissions is basically the same as that of traditional transmissions: the engine is first decoupled from the wheels, then gear shifting and speed adjustment are performed, and finally the speed-adjusted engine is engaged with the clutch or synchronizer.

[0004] However, the aforementioned shift control modes place high demands on the engine's torque response and control, and there is a problem of inertial torque impact during the shift process, which affects the smoothness of the vehicle. Summary of the Invention

[0005] In view of this, this application provides a shift control method, device, and hybrid vehicle that can utilize the fast and precise torque response characteristics of an electric motor, in conjunction with the control of a dual clutch, to counteract the influence of inertial torque during shifting, maintain power transmission, and thereby improve the smoothness and power of the shifting process.

[0006] The specific technical solution adopted in this application is as follows:

[0007] This application provides a shift control method, applied to a hybrid vehicle, wherein the transmission of the hybrid vehicle includes a first clutch and a second clutch, and the method includes:

[0008] Based on the first transmission ratio and the second transmission ratio, the inertial torque generated by the input shaft of the gearbox after shifting is determined, wherein the first transmission ratio is the transmission ratio of the gear set corresponding to the first clutch, the second transmission ratio is the transmission ratio of the gear set corresponding to the second clutch, the first clutch is the clutch to be disengaged, and the second clutch is the clutch to be engaged.

[0009] During gear shifting, the torque of the input shaft is adjusted according to the inertial torque, the torque of the input shaft being the torque applied to the input shaft by the power source of the hybrid vehicle.

[0010] Optionally, the torque of the input shaft includes the engine air circuit torque and the motor output torque;

[0011] The step of adjusting the torque of the input shaft based on the inertial torque includes:

[0012] The output torque of the motor is adjusted based on the inertial torque.

[0013] Optionally, adjusting the motor output torque based on the inertial torque includes:

[0014] When shifting up, the output torque of the motor is reduced, and the amount of reduction in the output torque of the motor is equal to the inertial torque.

[0015] When downshifting, the output torque of the motor is increased, and the increase in the output torque of the motor is equal to the inertial torque.

[0016] Optionally, the vehicle has a pre-stored relationship between shift times and the speed difference of the input shaft;

[0017] After adjusting the motor output torque based on the inertial torque, the method further includes:

[0018] During gear shifting, the actual rotational speed of the input shaft at the current moment is obtained;

[0019] When the actual rotational speed of the input shaft is not equal to the target rotational speed corresponding to the current moment, the output torque of the motor is adjusted a second time, wherein the target rotational speed is obtained based on the correspondence between the shift time and the rotational speed difference of the input shaft.

[0020] Optionally, determining the inertial torque generated by the input shaft of the transmission after the gear shift, based on the first transmission ratio and the second transmission ratio, includes:

[0021] The output speed difference of the gearbox before and after the gear shift is determined based on the first gear ratio and the second gear ratio;

[0022] The inertial torque is determined based on the output speed difference, the preset shift time, and the moment of inertia of the input shaft.

[0023] Optionally, the method further includes:

[0024] In response to an additional wheel-end torque demand, the target intake volume of the engine is obtained, the additional wheel-end torque demand being generated based on the operation of the accelerator pedal or brake pedal;

[0025] Determine the target engine airflow torque corresponding to the target intake volume;

[0026] Before the target engine air circuit torque is reached, the motor output torque is adjusted based on the real-time changes in the engine air circuit torque.

[0027] Optionally, adjusting the motor output torque based on the real-time changes in the engine's airflow torque includes:

[0028] The target torque of the input shaft is determined based on the additional wheel end torque requirement;

[0029] The target motor output torque is determined based on the target torque of the input shaft and the current engine air circuit torque, wherein the target motor output torque is the difference between the target torque of the input shaft and the current engine air circuit torque.

[0030] The motor is controlled to output torque according to the target motor output torque.

[0031] Optionally, in response to the additional wheel-end torque demand during the gear shifting process, the target motor output torque is determined based on the motor output torque before the gear shift, the inertial torque, and the additional wheel-end torque demand.

[0032] Another aspect of this application is to provide a shift control device, the device comprising:

[0033] The determining unit is configured to determine the inertial torque generated by the input shaft of the gearbox after a gear shift based on a first gear ratio and a second gear ratio, wherein the gearbox includes a first clutch and a second clutch, the first clutch being a clutch to be disengaged, the second clutch being a clutch to be engaged, the first gear ratio being the gear ratio of the gear set corresponding to the first clutch, and the second gear ratio being the gear ratio of the gear set corresponding to the second clutch.

[0034] The adjustment unit is configured to adjust the torque of the input shaft during gear shifting based on the inertial torque.

[0035] Another aspect of this application is to provide a hybrid vehicle for performing the above-described shift control method.

[0036] The shift control method provided in this application is applicable to hybrid vehicles with two clutches that perform shifting based on these two clutches. The clutch that needs to be disengaged is defined as the first clutch, and the clutch that needs to be engaged is defined as the second clutch. Based on the first transmission ratio of the gear set corresponding to the first clutch and the second transmission ratio of the gear set corresponding to the second clutch, the inertial torque generated by the input shaft of the transmission after shifting is determined, and the torque applied to the input shaft by the power source is adjusted according to the inertial torque so that the inertial torque is consumed, thereby avoiding the impact of inertial torque during shifting and improving the smoothness of the vehicle. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a schematic diagram of the structure of a hybrid vehicle provided in an embodiment of this application;

[0039] Figure 2 This is a first flowchart of a shift control method provided in an embodiment of this application;

[0040] Figure 3 This is a second flowchart of a shift control method provided in an embodiment of this application;

[0041] Figure 4 This is a third flowchart of a shift control method provided in an embodiment of this application;

[0042] Figure 5 This is a fourth flowchart of a shift control method provided in an embodiment of this application;

[0043] Figure 6 This is a torque transfer diagram of a dual clutch during gear shifting, provided in an embodiment of this application.

[0044] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0045] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0046] In recent years, with the rapid development of the social economy and the rapid increase in residents' income levels, people's demand for convenient travel has increased, leading to the booming development of the automotive industry. However, the continuous increase in vehicle ownership, the gradual depletion of fossil fuels, and the deterioration of the atmospheric environment have also brought about a series of social problems. However, the efficient transmission system of hybrid electric vehicles can significantly improve the vehicle's power and fuel economy, while reducing emissions and air pollution. Therefore, the development of hybrid electric vehicles is receiving increasing attention.

[0047] Most hybrid power systems in related technologies are developed based on traditional automatic transmissions. They consist of an electric motor integrated into the front or rear of a transmission such as AT (Automatic Transmission), AMT (Automated Manual Transmission), CVT (Continuously Variable Transmission), or DCT (Dual-clutch Transmission). This type of hybrid system is widely adopted by automakers due to its low R&D investment and low technological barriers. Its shift control mode basically follows that of traditional transmissions: the engine is first decoupled from the wheels, then gear shifting and speed adjustment are performed, and finally the speed-adjusted engine is engaged with the clutch or synchronizer.

[0048] It is evident that the electric motor's involvement is minimal throughout the gear shifting process, while placing high demands on the engine's torque response and control, thus impacting fuel economy. Furthermore, the inertial torque shock during gear shifts affects vehicle smoothness and reduces driving comfort.

[0049] To address the aforementioned problems, this application provides a gear shifting control method that avoids the impact of inertial torque during gear shifting, thereby improving vehicle smoothness. This gear shifting control method is applied to hybrid vehicles, and the executing entity can be a computer device. This computer device can be a controller on the hybrid vehicle or other computer device that establishes a communication connection with the hybrid vehicle via wired or wireless communication technology. For example, this computer device can be the ECU (Electronic Control Unit) of the hybrid vehicle. The hybrid vehicle is equipped with at least two power sources, including an engine and an electric motor. The transmission of the hybrid vehicle includes a first clutch and a second clutch, as well as gear sets corresponding to the first clutch and the second clutch.

[0050] To facilitate the explanation of the scheme in this application, Figure 1 The diagram illustrates the structure of a possible hybrid vehicle, comprising an engine 1, a first electric motor 2, and a second electric motor 3. The output shaft of the engine 1 is connected to the first electric motor 2 via a clutch 4, wherein the inner hub of the clutch 4 is connected to the crankshaft of the engine 1, and the outer hub is connected to the stator of the first electric motor 2. The rotor of the first electric motor 2 is connected to the input shaft 6 of a gearbox 5. The gearbox 5 contains a dual-clutch assembly 7, comprising a first clutch 71 and a second clutch 72. The first clutch 71 and the second clutch 72 share the same outer hub but have different inner hubs. The inner hubs of the first clutch 71 and the second clutch 72 are each connected to a gear set with different gear ratios, and the power output ends of the two gear sets are connected to the same output shaft 8. The output shaft 8 is connected to a wheel drive shaft 9 via other power transmission components to drive the wheels.

[0051] It is easy to understand that, Figure 1 The structure of the hybrid vehicle provided is merely for illustrative purposes of the shift control method provided in this application embodiment, and is not intended to limit the application of the shift control method provided in this application embodiment to this structure alone. In fact, the shift control method provided in this application embodiment can also be applied to other hybrid systems based on dual-clutch shifting, and the dual clutches can be two clutches integrated together or two independent clutches.

[0052] Figure 2 A flowchart of a shift control method provided in an embodiment of this application is shown below. Figure 2 As shown, the shift control method provided in this application embodiment can be applied to hybrid vehicles and includes the following steps:

[0053] Step 110: Determine the inertial torque generated by the input shaft of the gearbox after shifting gears based on the first transmission ratio and the second transmission ratio.

[0054] The transmission of a hybrid vehicle includes a first clutch and a second clutch. The gear set corresponding to the first clutch corresponds to a first gear ratio, and the gear set corresponding to the second clutch corresponds to a second gear ratio. During gear shifting, the vehicle is actually switching from outputting power at the first gear ratio to outputting power at the second gear ratio. Accordingly, the first clutch is the clutch to be disengaged, and the second clutch is the clutch to be engaged.

[0055] During gear shifting, the change in gear ratio causes a corresponding change in the engine and motor speeds, which in turn alters the input shaft speed, generating inertial torque. For example, during upshifting, the gear ratio decreases, and the engine and motor speeds correspondingly decrease. Therefore, during clutch slippage shifting, the decreased speed results in a positive inertial torque output to the input shaft's wheel end. Conversely, during downshifting, the gear ratio increases, and the engine and motor speeds correspondingly increase. Therefore, during clutch slippage shifting, the increased speed results in a negative inertial torque output to the input shaft's wheel end. Here, "positive" refers to the direction in which the driving force is transmitted, and "negative" refers to the direction opposite to the driving force transmission direction.

[0056] Step 120: During gear shifting, adjust the torque of the input shaft according to the inertial torque.

[0057] An input shaft generally refers to the shaft that connects the power source and the gearbox and is used to transmit power, for example... Figure 1 Input shaft 6. However, it should be noted that the number of input shafts can be more than one. When there are multiple power sources in the system, the number of input shafts can be two or even more. Accordingly, the torque of the input shaft at a certain moment includes the sum of the output torques of all power sources that input power to the transmission at that moment.

[0058] The inertial torque generated during gear shifts is the portion beyond the torque output from the power source to the input shaft. It typically impacts the wheel ends, causing vehicle jerking and affecting smoothness. To reduce or even avoid the impact caused by inertial torque, in this embodiment, the torque of the input shaft is adjusted based on the inertial torque. This adjusted input shaft can counteract the inertial torque, thereby ensuring smoothness during gear shifts and improving driving comfort. The input shaft torque refers to the torque applied to the input shaft by the power source of the hybrid vehicle.

[0059] Generally, a vehicle's torque demand typically includes accessory torque, driver-demanded torque (determined based on pedal opening), and friction torque. Accessory torque refers to the torque required for the normal operation of in-vehicle equipment such as air conditioning, radio, and displays. For hybrid vehicles, after collecting the vehicle's torque demand, the required torque is allocated to at least one of the engine and motor according to predefined rules. Unlike traditional transmissions that only consider engine torque during shift control, the shift control method for hybrid vehicles provided in this application requires consideration of the combined torque of both the engine and motor. Since the engine's torque response is slower than the motor's, a significant difference between the target torque and the actual torque often occurs during shift control, leading to shift shock.

[0060] Engine torque can be comprised of both intake torque and spark torque. During the engine's torque conversion process, the torque allocated to the engine is coordinated and output through both intake and spark paths. Intake torque is primarily achieved by altering the intake air volume within the cylinders. The desired intake air volume is calculated from the intake torque, which then determines the throttle opening. Simultaneously, the actual fuel injection quantity for each cylinder is calculated based on the air-fuel ratio, thus controlling the intake path. Spark torque is typically achieved through rapid torque adjustment by intervening in the ignition timing. By allowing the engine to change the ignition timing at the next ignition, engine torque can be rapidly altered within a certain range. Within this range, increasing the ignition timing increases the engine's torque output; however, if the ignition timing is too large, engine knocking can occur, resulting in a decrease in output torque.

[0061] During the engine's torque response, the intake torque response is slower and relatively stable, while the spark torque response is faster. Therefore, in traditional transmissions, when it is necessary to change the engine torque, the spark torque is usually used to initiate a rapid response, altering the ignition advance angle to deviate from the optimal angle, causing a change in the engine's output torque to meet the demand, and simultaneously changing the intake air volume in the cylinders. Then, as the intake torque changes slowly, the spark torque is adjusted accordingly until the intake torque can meet the demand, at which point the ignition advance angle also returns to the optimal angle.

[0062] In the shift control method of this application, torque control based on the two clutches is achieved based on the torque of the input shaft. This requires the input shaft torque to be sufficiently stable and representative of torque variation trends and the driver's torque demands. However, the actual torque of the transmission's input shaft includes the motor output torque and the engine output torque, which in turn includes air circuit torque and spark circuit torque. Since spark circuit torque, being a rapid torque, varies significantly and is not stable enough when interfered with, the actual torque of the input shaft is not suitable as the basis for torque control during shifting. Considering that air circuit torque is relatively stable, in this embodiment, the input shaft torque can be set to include both the engine's air circuit torque and the motor output torque.

[0063] When adjusting the torque of the input shaft, since the engine's air circuit torque response is slow while the motor's output torque response is fast, in some embodiments of this application, step 102 may further include: adjusting the motor output torque based on the inertial torque.

[0064] Since the current of a motor is easy to control, the output torque of the motor can be adjusted, for example, by regulating the motor current. Increasing the motor current increases the output torque, while decreasing the motor current decreases the output torque.

[0065] In some embodiments of this application, adjusting the motor output torque may further include: when shifting up a gear, controlling the motor output torque to decrease, wherein the decrease in motor output torque is equal to the inertial torque; and when shifting down a gear, controlling the motor output torque to increase, wherein the increase in motor output torque is equal to the inertial torque.

[0066] For example, such as Figure 1 As shown, if the first transmission ratio is greater than the second transmission ratio, switching from the first clutch to the second clutch is an upshift. The transmission ratio decreases, and consequently, the engine and motor speeds both drop. During the slip-and-grip shift between the first and second clutches, the decrease in speed results in a positive inertial torque being output to the wheel end. Therefore, to ensure smooth shifting, the fast torque response of the motor is utilized during the shifting speed adjustment phase to respond to the torque decrease. That is, during upshifting, the motor output torque is adjusted to reduce the torque change by an amount equal to the magnitude of the inertial torque. Consequently, the input shaft torque also decreases by an amount equal to the magnitude of the inertial torque, thus offsetting the positive inertial torque caused by the decrease in engine and motor speeds during upshifting, achieving a smooth shifting process.

[0067] If the first gear ratio is less than the second gear ratio, switching from the first clutch to the second clutch is a downshift. The gear ratio increases, and consequently, the engine and motor speeds both increase. During the slip-and-grip shift between the first and second clutches, the increased speed results in a negative inertial torque output to the wheel end. Therefore, to ensure smooth shifting, the fast torque response of the motor is utilized during the shift adjustment phase to respond to the increase in torque. That is, during downshifting, the motor output torque is adjusted to increase the torque change by an amount equal to the magnitude of the inertial torque. Consequently, the input shaft torque also increases by an amount equal to the magnitude of the inertial torque, thus counteracting the negative inertial torque caused by the increased engine and motor speeds during downshifting, achieving a smooth shifting process.

[0068] Therefore, the shift control method provided in this application utilizes the characteristics of the motor's fast and precise torque response, combined with the control of the dual clutch, to compensate for the inertial torque during the shift process, thereby offsetting the influence of the inertial torque and improving the smoothness of the shift process while maintaining uninterrupted power.

[0069] Theoretically, during gear shifting, the input shaft speed should change systematically with increasing shift time. For example, during upshifting, the input shaft speed should decrease linearly at a constant rate; during downshifting, it should increase linearly at a constant rate. However, in actual gear shifting, due to factors such as the precision deviation of the clutch hydraulic system, the clutch hydraulic response speed, the influence of oil temperature and environment on the clutch friction coefficient, the precision of engine output torque, and the engine output torque response speed, the input shaft torque usually does not change linearly. Therefore, it is difficult to guarantee that the gear shift will be completed within the preset shift time.

[0070] Therefore, in some embodiments of this application, the hybrid vehicle may pre-store the correspondence between shift time and the speed difference of the input shaft. Here, the correspondence refers to the correspondence under ideal conditions, such as a direct proportional relationship.

[0071] After adjusting the motor output torque based on the inertial torque, the shift control method may further include steps 210 and 220:

[0072] Step 210: During gear shifting, obtain the actual speed difference of the input shaft at the current moment.

[0073] At any point during a gear shift, the actual speed difference of the input shaft at that moment is obtained. For example, a hybrid vehicle can obtain the actual speed of the input shaft in real time using a speed detection device, and then determine the actual speed difference of the input shaft at the current moment according to the following formula:

[0074] The actual speed difference of the input shaft = the actual speed of the input shaft - the speed of the input shaft before shifting.

[0075] Optionally, the actual speed difference of the input shaft can be obtained when half of the preset shift time has elapsed.

[0076] For example, assuming the input shaft speed of the vehicle is 5000 rpm before shifting gears, and the preset shift time is 200 ms, if the actual speed of the input shaft is obtained at half the preset shift time, i.e., 100 ms, then the actual speed difference of the input shaft at that moment is 200 rpm.

[0077] Step 220: When the difference between the actual speed difference and the target speed difference at the current moment is greater than the set threshold, the motor output torque is adjusted a second time.

[0078] The target speed difference is obtained based on the correspondence between the pre-stored shift times in the vehicle and the speed difference of the input shaft. In some embodiments of this application, the threshold can be set to 20% of the target speed difference.

[0079] Continuing the previous example, assuming the input shaft speed should be 6000 rpm after shifting, based on the pre-stored correspondence between shift time and input shaft speed difference in the vehicle, it is determined that when the shift time is halfway through, the speed difference should also reach half of the target speed difference. That is, at 100ms, the target speed difference of the input shaft should be 500 rpm. At this point, the threshold is set to 500 rpm × 20% = 100 rpm. It can be seen that the actual speed difference of the input shaft at this time, 200 rpm, is greater than the preset threshold of 100 rpm. Therefore, a secondary adjustment of the motor output torque is needed to correct the speed difference in time. In this example, this means reducing the motor output torque to increase the input shaft speed, thereby ensuring that the shift can be completed within the preset shift time.

[0080] It is easy to understand that if the difference between the actual rotational speed of the input shaft and the target rotational speed at the current moment is less than or equal to the set threshold, then there is no need to adjust the motor output torque.

[0081] The vehicle also stores the correlation between the torque correction amount during secondary adjustments of the motor and the difference between the actual speed difference and the target speed difference of the input shaft. This relationship is typically directly proportional: the larger the difference between the actual and target speed differences, the larger the motor torque correction; conversely, the smaller the difference, the smaller the motor torque correction. For example, if the difference between the actual and target speed differences is 100 rpm, the torque correction is 10 Nm; if the difference is 200 rpm, the torque correction is 20 Nm, and so on.

[0082] In some embodiments, to reduce the frequency of changes in motor output torque and alleviate the control pressure on the motor, the difference between the actual speed difference and the target speed difference of the input shaft within a certain range can correspond to a motor torque. For example, when the difference between the actual speed difference and the target speed difference is 100-300 rpm, the torque correction is 20 Nm; when the difference is 300-500 rpm, the torque correction is 40 Nm, and so on. The correspondence between the torque correction during secondary adjustment and the difference between the actual speed difference and the target speed difference of the input shaft can be obtained through calibration during vehicle testing.

[0083] This embodiment of the application, by employing the above method, achieves the counteraction of the impact of inertial torque during gear shifting and ensures that the vehicle completes gear shifting within a preset shifting time. Specifically, the output torque of the motor during the secondary adjustment period is equal to the sum of the torque before shifting, the torque change to compensate for the inertial torque, and the torque correction amount. After the gear shift is completed, the motor output torque needs to be reduced by the torque correction amount, i.e., the torque correction amount is zero.

[0084] In some embodiments of this application, such as Figure 3 As shown, step 110 may also include:

[0085] Step 111: Determine the output speed difference of the gearbox before and after shifting gears based on the first transmission ratio and the second transmission ratio.

[0086] After obtaining the output speed of the transmission before the shift, the output speed of the transmission after the shift can be calculated based on the first and second transmission ratios, and the difference in output speed before and after the shift can also be calculated.

[0087] For example, assuming the first gear ratio is 1:10 and the second gear ratio is 1:8, the output speed of the transmission before shifting is 5000 rpm. When shifting, the transmission changes from the first gear ratio to the second gear ratio, and the gear increases. After shifting, the output speed of the transmission is 4000 rpm. Therefore, the difference in output speed of the transmission before and after shifting is 1000 rpm.

[0088] Step 112: Determine the inertial torque based on the output speed difference, the preset shift time, and the rotational inertia of the input shaft.

[0089] The preset shift time can be determined empirically or through real-vehicle testing and stored in the hybrid vehicle for later use, for example, in the hybrid vehicle's computer system. The input shaft's moment of inertia can also be obtained through real-vehicle testing and stored in the vehicle for later use, for example, in the hybrid vehicle's computer system.

[0090] The inertial torque can be calculated using the following formula:

[0091] Inertial torque = Output speed difference ÷ Preset shift time × Input shaft moment of inertia.

[0092] In some situations, the driver may also press the accelerator or brake pedal while shifting gears, meaning there is an additional wheel-end torque demand for acceleration or deceleration.

[0093] Therefore, in some embodiments of this application, such as Figure 4 As shown, the shift control method further includes the following steps 130 to 150:

[0094] Step 130: In response to the additional wheel-end torque demand, obtain the target intake volume of the engine.

[0095] Additional wheel-end torque demand is typically generated based on the operation of the accelerator or brake pedal. When the accelerator or brake pedal is actuated, it causes a change in the engine throttle opening, which in turn changes the engine's intake air volume. In practice, when the actuation of the accelerator or brake pedal is detected, it is determined that there is an additional wheel-end torque demand, and the target intake air volume of the engine is obtained.

[0096] The air passage torque corresponding to the target intake volume reflects the engine air passage torque before shifting and the additional wheel end torque demand generated during shifting.

[0097] Step 140: Determine the target engine air circuit torque corresponding to the target intake volume.

[0098] After determining the target intake volume, the target engine airflow torque can be calculated using the following formula:

[0099] Engine airflow torque = intake air mass × calorific value × air-fuel ratio ÷ (377 × engine speed)

[0100] Wherein, air-fuel ratio = intake air mass ÷ fuel mass. Air-fuel ratio is the mass ratio between air and fuel in the mixture. It is generally expressed as the mass of air consumed when 1 kg of fuel is completely burned. This value is the test calibration value. Optionally, the range of air-fuel ratio is 12-13.

[0101] The intake air mass is calculated as intake air volume × air density. The relationship between intake air volume and throttle opening at different engine speeds can be obtained through bench calibration and then corrected based on ambient atmospheric pressure. Air density is related to factors such as temperature and pressure and can be obtained through testing or by referring to tables.

[0102] The calorific value is the heat released by the complete combustion of 1 kg of fuel oil. Calorific value = 46000 × fuel oil mass. It can be determined through testing or by looking up a table. Optionally, the calorific value can be 46000 KJ / kg.

[0103] Step 150: Before reaching the target engine air circuit torque, adjust the motor output torque based on the real-time changes in the engine air circuit torque.

[0104] The response of engine airflow torque is relatively slow. At the instant the intake air volume changes, the airflow torque remains constant and then slowly adjusts to the corresponding airflow torque over time. When the engine's airflow torque is not used to respond to changes in the input shaft torque, the slow response speed causes a noticeable delay and jerking when the driver operates the accelerator or brake pedals. To address this issue, in this embodiment, the additional wheel-end torque demand is initially met by the motor's output torque. Then, as the airflow torque changes in real time, the motor's output torque is adjusted until the airflow torque fully responds to the additional wheel-end torque demand.

[0105] For example, suppose the driver presses the accelerator pedal while shifting gears, applying an additional 5000 Nm of wheel-end torque. In practice, since the air circuit torque has not yet had time to respond when the accelerator pedal is pressed, the electric motor responds to the additional wheel-end torque demand first, that is, the motor output torque increases, thereby providing the 5000 Nm of additional torque to the wheel ends. At the same time, as the engine air circuit torque gradually increases, the motor output torque decreases until the air circuit torque provides the 5000 Nm of additional torque to the wheel ends.

[0106] In some embodiments of this application, such as Figure 5 As shown, step 150 may include:

[0107] Step 151: Determine the target torque of the input shaft based on the additional wheel end torque requirement;

[0108] The target torque of the input shaft includes the torque of the input shaft before shifting, as well as the input shaft torque corresponding to the additional wheel-end torque requirement.

[0109] The target torque of the input shaft can be calculated using the following formula:

[0110] Target torque of input shaft = Torque of input shaft before shift + Additional wheel end torque requirement ÷ Speed ​​ratio of current transmission gear set

[0111] Step 152: Determine the target motor output torque based on the target torque of the input shaft and the current engine air circuit torque.

[0112] The target motor output torque is the difference between the target torque of the input shaft and the current engine air circuit torque.

[0113] For example, at the moment the accelerator pedal is depressed, the engine airflow torque instantaneously remains unchanged from the engine airflow torque before the gear shift. At this time:

[0114] Target motor output torque = target torque of input shaft - engine air circuit torque before shifting.

[0115] In the next moment, the engine torque changes, but it still cannot meet all the additional torque requirements. At this time:

[0116] Target motor output torque = Target torque of input shaft - Current engine air circuit torque

[0117] The current engine airflow torque can be obtained through acquisition instruments, such as a torque sensor mounted on the engine crankshaft.

[0118] Step 153: Control the motor to output torque according to the target motor output torque.

[0119] After determining the target motor output torque, the motor is controlled to output torque according to the target motor output torque. During this process, the magnitude of the motor output torque can be controlled by adjusting the motor current.

[0120] It should be noted that steps 130-150 and 151-153 above can be applied to control the additional wheel-end torque demand generated during gear shifting, as well as to control the additional wheel-end torque demand generated during normal driving (non-gear shifting).

[0121] Specifically, for cases where additional wheel-end torque is required during gear shifting, the target motor output torque is determined based on the motor output torque, inertial torque, and additional wheel-end torque requirement before gear shifting, in response to the additional wheel-end torque requirement during gear shifting.

[0122] In this embodiment of the application, the shift control method further includes:

[0123] During gear shifting, the second clutch engages synchronously with the disengagement of the first clutch to maintain a constant output torque. The output torque of each clutch refers to the torque output by its driven part, which is equal to the torque input to its corresponding gear set. In this embodiment, the output torque of the clutch is the sum of the output torques of the first and second clutches.

[0124] In some embodiments, the torque output by the clutch corresponds to the clutch oil pressure; however, when the torque is adjusted based on oil pressure, the torque response is relatively slow. For example... Figure 6As shown, for example, during gear shifting, the first clutch first reduces the oil pressure to the target oil pressure, which corresponds to the target torque of the input shaft. Because the clutch's torque response is relatively slow, there is a plateau period to allow the clutch's output torque to reach the target torque of the input shaft. Afterward, the output torque of the first clutch can be reduced at a preset speed, while the torque of the second clutch is increased at the same speed, achieving torque transfer between the two clutches and entering the clutch slippage speed adjustment stage. During this period, the sum of the output torques of the first and second clutches remains constant, thus achieving uninterrupted gear shifting and ensuring a smooth power transfer during the shift process.

[0125] In summary, the shift control method provided in this application utilizes the characteristic that the engine air path torque is unaffected by the torque intervention during gearbox shifts, and the characteristic that the torque allocated to the motor based on the additional wheel end torque demand and torque distribution strategy is also unaffected by the gearbox shift torque intervention. The sum of the engine air path torque and the motor output torque is used as the input shaft torque. This not only fully utilizes the fast torque response of the motor in the hybrid transmission, but also considers the difference in response speed between the engine air path torque and the motor torque. When performing a shift control method based on the switching of two clutches, the inertial torque calculated based on the aforementioned input shaft torque is used as the intervention part for the motor output torque. During upshifting, a portion of the torque is subtracted from the input shaft torque to obtain the actual torque; during downshifting, a portion of the torque is compensated from the input shaft torque to obtain the actual torque. This torque change is responded to by the motor, thus replacing the control process of using the engine to respond to torque changes in traditional fuel vehicles with the motor. Therefore, it is more beneficial for stable engine control and smooth shifting.

[0126] This application embodiment also provides a gear shift control device, the device comprising:

[0127] The determining unit is configured to determine the inertial torque generated by the input shaft of the gearbox after a gear shift based on a first transmission ratio and a second transmission ratio, wherein the first transmission ratio is the transmission ratio of the gear set corresponding to the first clutch, and the second transmission ratio is the transmission ratio of the gear set corresponding to the second clutch.

[0128] The adjustment unit is configured to adjust the target torque of the input shaft based on the inertial torque during gear shifting.

[0129] In the shift control device provided in this application embodiment, the torque of the input shaft is adjusted according to the inertial torque, so that the adjusted input shaft can counteract the inertial torque, thereby avoiding the impact of inertial torque during the shifting process and improving the smoothness of the vehicle during the shifting process.

[0130] This application also provides a hybrid vehicle whose transmission includes a first clutch and a second clutch, and the hybrid vehicle is used to execute the shift control method described in any of the above embodiments.

[0131] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the application disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only.

[0132] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A gear shifting control method, characterized in that, The method is applied to a hybrid vehicle, wherein the transmission of the hybrid vehicle includes a first clutch and a second clutch, and the method includes: Based on the first transmission ratio and the second transmission ratio, the inertial torque generated by the input shaft of the gearbox after shifting is determined, wherein the first transmission ratio is the transmission ratio of the gear set corresponding to the first clutch, the second transmission ratio is the transmission ratio of the gear set corresponding to the second clutch, the first clutch is the clutch to be disengaged, and the second clutch is the clutch to be engaged. During gear shifting, the torque of the input shaft is adjusted according to the inertial torque, the torque of the input shaft being the torque applied to the input shaft by the power source of the hybrid vehicle; The torque of the input shaft includes the output torque of the motor, and adjusting the torque of the input shaft according to the inertial torque includes: adjusting the output torque of the motor according to the inertial torque; The vehicle has a pre-stored correspondence between shift times and the speed difference of the input shaft. After adjusting the motor output torque based on the inertial torque, the method further includes: During gear shifting, when half of the preset shifting time has elapsed, the actual speed difference of the input shaft at the current moment is obtained, wherein the actual speed difference of the input shaft = the actual speed of the input shaft - the speed of the input shaft before the shift; When the difference between the actual speed difference and the target speed difference corresponding to the current moment is greater than a preset threshold, the motor output torque is adjusted a second time to ensure that the shift is completed within the preset shift time. The target speed difference is obtained based on the correspondence between the shift time and the speed difference of the input shaft. The preset threshold is 20% of the target speed difference. The motor output torque during the second adjustment period is equal to the sum of the torque before shift, the torque change for compensating inertia torque, and the torque correction.

2. The method according to claim 1, characterized in that, The torque of the input shaft includes the engine air circuit torque and the motor output torque.

3. The method according to claim 1, characterized in that, The step of adjusting the motor output torque based on the inertial torque includes: When shifting up, the output torque of the motor is reduced, and the amount of reduction in the output torque of the motor is equal to the inertial torque. When downshifting, the output torque of the motor is increased, and the increase in the output torque of the motor is equal to the inertial torque.

4. The method according to any one of claims 1-3, characterized in that, The step of determining the inertial torque generated by the input shaft of the gearbox after shifting, based on the first transmission ratio and the second transmission ratio, includes: The output speed difference of the gearbox before and after the gear shift is determined based on the first gear ratio and the second gear ratio; The inertial torque is determined based on the output speed difference, the preset shift time, and the moment of inertia of the input shaft.

5. The method according to claim 2, characterized in that, The method further includes: In response to an additional wheel-end torque demand, the target intake volume of the engine is obtained, the additional wheel-end torque demand being generated based on the operation of the accelerator pedal or brake pedal; Determine the target engine airflow torque corresponding to the target intake volume; Before the target engine air circuit torque is reached, the motor output torque is adjusted based on the real-time changes in the engine air circuit torque.

6. The method according to claim 5, characterized in that, The adjustment of the motor output torque based on the real-time changes in the engine's airflow torque includes: The target torque of the input shaft is determined based on the additional wheel end torque requirement; The target motor output torque is determined based on the target torque of the input shaft and the current engine air circuit torque, wherein the target motor output torque is the difference between the target torque of the input shaft and the current engine air circuit torque. The motor is controlled to output torque according to the target motor output torque.

7. The method according to claim 6, characterized in that, In response to the additional wheel-end torque demand during gear shifting, the target motor output torque is determined based on the motor output torque before gear shifting, the inertial torque, and the additional wheel-end torque demand.

8. A gear shifting control device, characterized in that, The device includes: The determining unit is configured to determine the inertial torque generated by the input shaft of the gearbox after a gear shift based on a first gear ratio and a second gear ratio, wherein the gearbox includes a first clutch and a second clutch, the first clutch being a clutch to be disengaged, the second clutch being a clutch to be engaged, the first gear ratio being the gear ratio of the gear set corresponding to the first clutch, and the second gear ratio being the gear ratio of the gear set corresponding to the second clutch. The adjustment unit is configured to adjust the torque of the input shaft during gear shifting based on the inertial torque, wherein the torque of the input shaft is the torque applied to the input shaft by the power source of the hybrid vehicle. The torque of the input shaft includes the motor output torque, and the adjustment unit is further configured to adjust the motor output torque according to the inertial torque. The vehicle has a pre-stored correspondence between shift times and the speed difference of the input shaft, and the shift control device is further configured to: During gear shifting, when half of the preset shifting time has elapsed, the actual speed difference of the input shaft at the current moment is obtained, wherein the actual speed difference of the input shaft = the actual speed of the input shaft - the speed of the input shaft before the shift; When the difference between the actual speed difference and the target speed difference corresponding to the current moment is greater than a preset threshold, the motor output torque is adjusted a second time to ensure that the shift is completed within the preset shift time. The target speed difference is obtained based on the correspondence between the shift time and the speed difference of the input shaft. The preset threshold is 20% of the target speed difference. The motor output torque during the second adjustment period is equal to the sum of the torque before shift, the torque change for compensating inertia torque, and the torque correction.

9. A hybrid vehicle, characterized in that, The vehicle is used to perform the shift control method according to any one of claims 1-7.

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