Engine combustion judgment method and device

Abstract

The invention discloses an engine combustion judgment method and device, and the method comprises the steps: obtaining the theoretical torque of an engine, the output torque of a generator, the rotating speed of a generator shaft, the rotating speed of an engine shaft, the rotational inertia of the generator and the rotational inertia of the engine in an engine power split mode; according to the output torque of the generator, the rotating speed of the rotating shaft of the generator, the rotating speed of the rotating shaft of the engine, the rotational inertia of the generator and the rotational inertia of the engine, the estimated torque of the engine is obtained; and comparing the estimated torque of the engine with the theoretical torque of the engine, and judging whether the interior of the engine cylinder is actually combusted or not according to a comparison result. Therefore, by accurately and indirectly estimating the engine torque, the authenticity of engine combustion is effectively judged, and reliable and safe operation of a vehicle is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy vehicles, and in particular to a method and device for judging engine combustion. Background Art

[0002] For hybrid vehicles, when the hybrid mode is the power split mode, after the generator outputs positive torque to drag the engine to start, the engine outputs positive torque and runs normally. The actual torque of the engine is related to parameters such as the engine fuel energy density, ignition efficiency and intake volume. In the prior art, it is generally obtained through actual bench calibration. However, the premise of this method is that the engine cylinder is truly burned.

[0003] In actual operation, it is possible that there is no real combustion in the engine cylinder. However, at this time, the calibrated actual engine torque can still be obtained by looking up the table and other methods. Because when the engine speed is controlled, the generator outputs positive torque to keep the engine at the corresponding speed, it is impossible to judge whether there is real combustion in the engine cylinder only by the engine torque and speed. If there is no real combustion in the engine cylinder, it may cause the vehicle to lack power and reduce comfort. In severe cases, it may even cause power loss and cause the vehicle to break down. Summary of the invention

[0004] In view of the above problems, the present invention is proposed to provide an engine combustion judgment method and device, which can effectively judge the authenticity of engine combustion by accurately and indirectly estimating engine torque, thereby ensuring reliable and safe operation of the vehicle.

[0005] According to a first aspect of the present invention, there is provided an engine combustion judgment method, which is applied to a hybrid vehicle;

[0006] The method comprises:

[0007] In the engine power split mode, the theoretical torque of the engine, the output torque of the generator, the generator shaft speed, the engine shaft speed, the rotational inertia of the generator and the rotational inertia of the engine are obtained;

[0008] Obtaining an estimated torque of the engine according to the generator output torque, the generator shaft speed, the engine shaft speed, the rotational inertia of the generator and the rotational inertia of the engine;

[0009] The estimated torque of the engine is compared with the theoretical torque of the engine, and whether combustion is actually occurring in the cylinder of the engine is determined based on the comparison result.

[0010] Optionally, obtaining the estimated torque of the engine according to the generator output torque, the generator shaft speed, the engine shaft speed, the rotational inertia of the generator and the rotational inertia of the engine includes:

[0011] Get the gear status of the hybrid vehicle;

[0012] If the gear state is the power split gear, the estimated torque of the engine is obtained according to the generator output torque, the generator shaft speed, the engine shaft speed, the rotational inertia of the generator and the rotational inertia of the engine;

[0013] If the gear state is the direct drive gear, then in the process of changing from the power split gear to the direct drive gear, the estimated torque of the engine is obtained according to the generator output torque and the generator shaft speed.

[0014] Optionally, obtaining the estimated torque of the engine according to the generator output torque, the generator shaft speed, the engine shaft speed, the rotational inertia of the generator and the rotational inertia of the engine includes:

[0015] Determining the inertia torque of the generator according to the generator shaft speed and the rotational inertia of the generator;

[0016] Determining the inertia torque of the engine according to the engine shaft speed and the rotational inertia of the engine;

[0017] The estimated torque of the engine is obtained according to the inertia torque of the generator, the inertia torque of the engine, the output torque of the generator and a preset gear ratio.

[0018] Optionally, obtaining the estimated torque of the engine according to the inertia torque of the generator, the inertia torque of the engine, the generator output torque and a preset gear ratio includes:

[0019] Obtaining an engine target speed corresponding to the power split gear position;

[0020] determining an inertia torque correction coefficient according to the target engine speed, the engine shaft speed, and the generator shaft speed;

[0021] According to the inertia torque correction coefficient, the inertia torque of the engine and the inertia torque of the generator are respectively corrected to obtain the corrected inertia torque of the engine and the corrected inertia torque of the generator;

[0022] The estimated torque of the engine is obtained according to the corrected inertia torque of the engine, the corrected inertia torque of the generator, the generator output torque, and the gear ratio.

[0023] Optionally, determining the inertia torque correction coefficient according to the target engine speed, the engine shaft speed, and the generator shaft speed includes:

[0024] Determining a speed difference according to the target engine speed and the engine shaft speed;

[0025] Determining a target angular acceleration according to the generator shaft speed and the engine shaft speed;

[0026] According to the speed difference and the target angular acceleration, the inertia torque correction coefficient is determined by searching in a preset correction coefficient table; the correction coefficient table includes a calibrated speed difference and a calibrated angular acceleration, and the correction coefficient table also includes a calibrated correction coefficient corresponding to the calibrated speed difference and the calibrated angular acceleration.

[0027] Optionally, obtaining the estimated torque of the engine according to the generator output torque and the generator shaft speed includes:

[0028] Obtaining a target speed of the generator corresponding to the direct drive gear;

[0029] Determining the generator shift speed regulating torque according to the generator target speed and the generator shaft speed;

[0030] The estimated torque of the engine is obtained according to the generator shift speed regulation torque, the generator output torque and a preset gear ratio.

[0031] Optionally, in the engine power split mode, obtaining the theoretical torque of the engine, the output torque of the generator, the generator shaft speed, the engine shaft speed, the rotational inertia of the generator, and the rotational inertia of the engine includes:

[0032] If the engine shaft speed is greater than the speed threshold, after a preset time, it is determined to be in the engine power split mode;

[0033] In the engine power split mode, the theoretical torque of the engine, the output torque of the generator, the generator shaft speed, the engine shaft speed, the rotational inertia of the generator and the rotational inertia of the engine are obtained.

[0034] Optionally, comparing the estimated torque of the engine with the theoretical torque of the engine comprises:

[0035] Get the front wheel speed and rear wheel speed of the vehicle;

[0036] determining a wheel speed difference according to the front wheel speed and the rear wheel speed;

[0037] determining validity of the estimated torque according to the wheel speed difference;

[0038] If it is determined that the estimated torque is valid, the estimated torque of the engine is compared with a theoretical torque of the engine.

[0039] Optionally, the method further includes:

[0040] If the difference between the theoretical torque of the engine and the estimated torque of the engine is greater than a target threshold, it is determined that combustion in the cylinder of the engine has failed;

[0041] If the difference between the theoretical torque of the engine and the estimated torque of the engine is less than or equal to the target threshold, it is determined that real combustion occurs in the cylinder of the engine.

[0042] According to a second aspect of the present invention, there is provided an engine combustion judgment device, comprising:

[0043] An acquisition module, used for acquiring the theoretical torque of the engine, the output torque of the generator, the generator shaft speed, the engine shaft speed, the rotational inertia of the generator and the rotational inertia of the engine in the engine power split mode;

[0044] a torque estimation module, configured to obtain an estimated torque of the engine according to the generator output torque, the generator shaft speed, the engine shaft speed, the generator moment of inertia, and the engine moment of inertia;

[0045] The judgment module is used to compare the estimated torque of the engine with the theoretical torque of the engine, and judge whether there is real combustion in the cylinder of the engine according to the comparison result.

[0046] The above one or more technical solutions in the embodiments of this specification have at least the following technical effects:

[0047] The embodiment of this specification provides a method and device for judging engine combustion, which obtains the theoretical torque of the engine, the output torque of the generator, the speed of the generator shaft, the speed of the engine shaft, the moment of inertia of the generator, and the moment of inertia of the engine in the engine power split mode; obtains the estimated torque of the engine according to the output torque of the generator, the speed of the generator shaft, the speed of the engine shaft, the moment of inertia of the generator, and the moment of inertia of the engine; compares the estimated torque of the engine with the theoretical torque of the engine, and judges whether the combustion is real in the cylinder of the engine according to the comparison result. In this way, by accurately and indirectly estimating the engine torque, the authenticity of the engine combustion can be effectively judged, and the reliable and safe operation of the vehicle can be guaranteed.

[0048] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented according to the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Also, throughout the accompanying drawings, the same reference figures are used to represent the same components. In the drawings:

[0050] Figure 1 A flow chart of an engine combustion judgment method in an embodiment of the present invention is shown.

[0051] Figure 2 A structural diagram of a power split mode multi-speed hybrid transmission in an embodiment of the present invention is shown.

[0052] Figure 3 A schematic diagram showing the input and output torque relationship of each component in a single planetary gear mechanism in an embodiment of the present invention is shown.

[0053] Figure 4 A block diagram of an engine combustion judgment device in an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0054] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0055] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0056] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0057] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0058] In hybrid vehicles, Figure 2 As shown, the engine's flywheel is connected to the planet carrier of the single planetary gear, the generator is connected to the sun gear, and the ring gear is connected to the left and right sides of the S1 synchronizer (i.e. Figure 2 The S1L and S1R in the transmission are connected to the wheels through the differential and the half shafts with two sets of gear trains of different speed ratios. The drive motor and another set of gear trains are also connected to the wheels through the differential and the half shafts. Among them, when the S2 synchronizer is in the middle position and the left or right side of the S1 synchronizer is engaged, two hybrid transmission gears with different speed ratios (i.e., ECVT1 gear and ECVT2 gear) are formed; the left and right sides of the S1 synchronizer and the left and right sides of the S2 synchronizer are respectively combined in pairs, which can realize the four direct drive gears of the engine (i.e., 1st gear, 2nd gear, 3rd gear and 4th gear). The S2 synchronizer is connected on the left side and the S1 synchronizer is located in the middle, which is a series gear; when both the S1 and S2 synchronizers are located in the middle, it is a neutral gear, i.e., a pure electric EV gear (the hybrid vehicle is driven by the power battery and the drive motor). The shift drum rotates to different positions (station 1-station 10), and the two synchronizers are controlled to different positions, corresponding to different gears. And the shift drum position change is performed in sequence, as shown in Table 1 below. Among them, in ECVT1 gear or ECVT2 gear, after the engine power is transmitted to the planetary carrier through the gearbox input shaft, part of the power is transmitted to the generator through the sun gear, and the other part of the power is transmitted to the wheel end through the ring gear system, thereby realizing the engine power split. In addition, the electric energy generated by the generator or the electric energy directly provided by the power battery is output to the drive motor in parallel through the gear system to the wheel end. The hybrid mode under this working condition is defined as the ECVT power split mode.

[0059]

[0060] Table 1

[0061] In actual operation, there may be a situation where there is no real combustion in the engine cylinder. Because when the engine speed is controlled, the generator outputs positive torque to keep the engine at a certain speed, so it is impossible to judge whether there is real combustion in the engine cylinder only by the engine torque and speed.

[0062] At present, the air-fuel ratio measured by the engine oxygen sensor can be used to determine the actual combustion situation in the engine cylinder. An air-fuel ratio that is too high or too low can be considered as an engine combustion failure. However, the premise of using the oxygen sensor to judge is that the engine has been burned and the sensor temperature has reached a certain value. It is not applicable to the working conditions when the engine is started, and has certain limitations.

[0063] Based on the above situation, in the power split mode, the engine torque can be indirectly estimated by the torque of other power components such as the generator. When the difference between the directly calculated engine torque and the indirectly estimated engine torque exceeds the target threshold, the engine combustion is considered to have failed.

[0064] Specifically, the embodiment of the present invention provides an engine combustion judgment method, combining Figure 1 The engine combustion determination method includes steps 101 to 103:

[0065] Step 101: in the engine power split mode, obtaining the theoretical torque of the engine, the output torque of the generator, the generator shaft speed, the engine shaft speed, the rotational inertia of the generator and the rotational inertia of the engine;

[0066] In this embodiment, the power split mode refers to a hybrid mode in which the electric energy generated by the generator or provided by the power battery directly to the drive motor is then output in parallel to the wheel ends through the gear train.

[0067] The theoretical torque of an engine refers to the engine torque obtained by looking up a table after the generator outputs positive torque to drag the engine to start, assuming that the engine is outputting positive torque and running normally.

[0068] Generator output torque, generator shaft speed, and engine shaft speed can be acquired through real-time acquisition. The rotational inertia of the generator and the engine are set constants and can also be directly acquired.

[0069] It should be noted that to calculate the estimated torque of the engine, the engine must first be fully started and enter stable operation. After the engine is started, it will be detected whether it is in the engine power split mode.

[0070] In this embodiment, the engine speed can be used to determine whether the engine has been started. If the engine shaft speed is greater than a speed threshold, the engine is considered to have been started. The speed threshold may be 800 rpm.

[0071] In actual logic, a preset time confirmation (for example, the preset time is 1 second) may be added to ensure that the engine is fully started and enters a stable operating state.

[0072] Specifically, if the engine shaft speed is greater than the speed threshold, then after a preset time, it is determined to be in the engine power split mode;

[0073] In the engine power split mode, the theoretical torque of the engine, the output torque of the generator, the generator shaft speed, the engine shaft speed, the rotational inertia of the generator and the rotational inertia of the engine are obtained.

[0074] It should be noted that whether the vehicle is in the power split mode can be determined by the gear state. If the current gear state is the power split gear (eg, ECVT1 gear or ECVT2 gear), the vehicle is considered to be in the power split mode.

[0075] In addition, during the process of the ECVT gear being in the direct drive gear, the present embodiment considers that the actual hybrid mode is still the power split mode. The direct drive gear includes: the 1st gear, the 2nd gear, the 3rd gear and the 4th gear in Table 1.

[0076] For example: if the current gear of the hybrid vehicle is ECVT1 gear or ECVT2 gear, it is in the power split mode; if it is detected that the gear changes from ECVT1 gear to 2 gear, then in the process of changing from ECVT1 gear to 2 gear, it is considered to be still in the power split mode.

[0077] Step 102: Obtaining an estimated torque of the engine according to the generator output torque, the generator shaft speed, the engine shaft speed, the generator moment of inertia, and the engine moment of inertia;

[0078] In this embodiment, the calculation method of the estimated torque is slightly different in view of different power split modes.

[0079] In one embodiment, if the power split mode is in stable operation, that is, the gear state is the power split gear (for example, ECVT1 gear or ECVT2 gear), the estimated torque of the engine can be obtained according to the generator output torque, the generator shaft speed, the engine shaft speed, the generator moment of inertia and the engine moment of inertia;

[0080] In one embodiment, if the gear state is the direct drive gear, in the process of changing from the power split gear to the direct drive gear, the estimated torque of the engine can be obtained according to the generator output torque and the generator shaft speed.

[0081] Step 103: Compare the estimated torque of the engine with the theoretical torque of the engine, and determine whether combustion actually occurs in the engine cylinder based on the comparison result.

[0082] In this embodiment, after the estimated torque is obtained, the estimated torque is compared with the theoretical torque to determine whether the engine cylinder is actually burning. If the engine cylinder is not actually burning, it means that the work done in the engine cylinder is insufficient, and the estimated torque of the engine will be significantly less than the theoretical torque. If the engine cylinder is actually burning, the indirectly obtained estimated torque is relatively close to the theoretical torque.

[0083] Therefore, this embodiment presets a target threshold based on the engine calibration experiment.

[0084] If the difference between the theoretical torque of the engine and the estimated torque of the engine is greater than a target threshold, it is determined that combustion in the cylinder of the engine has failed, that is, no real combustion has occurred;

[0085] If the difference between the theoretical torque of the engine and the estimated torque of the engine is less than or equal to the target threshold, it is determined that real combustion occurs in the cylinder of the engine.

[0086] In summary, this embodiment can effectively determine the authenticity of combustion in the engine cylinder by accurately and indirectly estimating the engine torque, so that when combustion fails in the engine cylinder, the engine can be stopped in time to avoid the generator always outputting positive torque to reverse the engine operation due to the engine not igniting and burning, and at the same time ensure the reliable and safe operation of the vehicle.

[0087] In the above embodiments, it is mentioned that in different power split modes, the calculation method of the estimated torque is slightly different. Among them, for the power split mode in stable operation, the estimated torque can be determined by referring to the following steps:

[0088] Determining the inertia torque of the generator according to the generator shaft speed and the rotational inertia of the generator;

[0089] Determining the inertia torque of the engine according to the engine shaft speed and the rotational inertia of the engine;

[0090] The estimated torque of the engine is obtained according to the inertia torque of the generator, the inertia torque of the engine, the output torque of the generator and a preset gear ratio.

[0091] Specifically, combined with Figure 3As shown, the torque relationship analysis under the single planetary gear dynamics and power split mode is as follows:

[0092] According to the motion and dynamics analysis of a single planetary gear, the speed relationship between the sun gear, ring gear and planet carrier is:

[0093] n S +Kn R =(1+K)n PC

[0094] The torque relationship acting on these three components is:

[0095] T S :T R :T PC =1:K:-(1+K)

[0096] Among them, n s is the sun gear speed, n R is the ring gear speed, n pc is the planet carrier speed, T s is the sun gear torque, T R is the ring gear torque, T PC is the planet carrier torque. K=Z R :Z S , K is the number of teeth on the gear ring Z R and the number of sun gear teeth Z S The gear ratio.

[0097] Based on the motion and dynamics analysis of the planetary gearbox components and the component connection relationship of the hybrid transmission structure, in the power split mode, the torque relationship between the input and output torque of the single planetary gearbox engine, generator and vehicle load end after considering the component inertia is as follows, and the relationship between the estimated torque of the engine and the output torque of the generator can be further obtained:

[0098]

[0099] Where: T e is the estimated torque of the engine, T P1 is the output torque of the generator, T Sin is the sun gear input torque, T Sout is the sun gear output torque, Js is the sun gear moment of inertia, ω S is the sun gear angular velocity, T PCin is the planet carrier input torque, J PC is the planet carrier moment of inertia, ω PC is the planet carrier angular velocity, n S is the sun gear speed, n P1 is the generator shaft speed, n PC is the planet carrier speed, n eis the engine shaft speed, T PCout is the output torque of the planet carrier, K is the gear ratio, ω P1 Angular velocity of the generator shaft, ω e is the angular velocity of the engine shaft, T Rin is the ring gear input torque, T Rout is the ring gear output torque, J R is the ring gear moment of inertia.

[0100] The angular velocity of the engine can be determined based on the engine shaft speed, and then the inertia torque of the engine can be calculated based on the engine angular velocity and the engine's rotational inertia.

[0101] The angular velocity of the generator is determined based on the generator shaft speed, and then the inertia torque of the generator is calculated based on the generator angular velocity and the generator's rotational inertia.

[0102] Finally, the estimated torque of the engine can be calculated based on the inertia torque of the generator, the inertia torque of the engine, the generator output torque and the preset gear ratio.

[0103] It should be noted that when calculating the inertia torque of the generator and the engine, the angular acceleration is calculated by low-pass filtering after the speed difference operation. When the angular velocity is large, the accuracy is lower. In addition, when the engine is speed controlled and the speed difference is large (such as when the engine has just started and has not stabilized), the accuracy of the inertia torque will also be reduced. Therefore, the inertia torque is corrected according to the target angular acceleration and the speed difference with a certain calibrable correction coefficient. The specific steps may include:

[0104] Obtaining an engine target speed corresponding to the power split gear position;

[0105] determining an inertia torque correction coefficient according to the target engine speed, the engine shaft speed, and the generator shaft speed;

[0106] According to the inertia torque correction coefficient, the inertia torque of the engine and the inertia torque of the generator are respectively corrected to obtain the corrected inertia torque of the engine and the corrected inertia torque of the generator;

[0107] The estimated torque of the engine is obtained according to the corrected inertia torque of the engine, the corrected inertia torque of the generator, the generator output torque, and the gear ratio.

[0108] Among them, the power split gears of this embodiment include ECVT1 gear and ECVT2 gear. Each power split gear has a corresponding engine target speed. According to the engine target speed and the engine shaft speed, the speed difference can be determined. Then, according to the generator shaft speed and the engine shaft speed, the target angular acceleration is calculated; specifically, it is necessary to first calculate the angular acceleration of the generator and the angular acceleration of the engine, and then take the larger value from the angular acceleration of the generator and the angular acceleration of the engine as the target angular acceleration.

[0109] Then, according to the speed difference and the target angular acceleration, the inertia torque correction coefficient is determined by searching in a preset correction coefficient table; the correction coefficient table includes a calibrated speed difference and a calibrated angular acceleration, and the correction coefficient table also includes a calibrated correction coefficient corresponding to the calibrated speed difference and the calibrated angular acceleration. The data in the correction coefficient table and the corresponding relationship between the data can be obtained through calibration experiments.

[0110] Finally, the inertia torque of the engine and the inertia torque of the generator are multiplied by the inertia torque correction coefficient to obtain the corrected inertia torque of the engine and the corrected inertia torque of the generator. When calculating the estimated torque, the corrected inertia torque of the engine and the corrected inertia torque of the generator are substituted into the above formula for calculation.

[0111] For another power split mode, that is, in the process of switching from power split gear to direct drive gear, the estimated torque can be calculated by referring to the following steps:

[0112] Obtaining a target speed of the generator corresponding to the direct drive gear;

[0113] Determining the generator shift speed regulating torque according to the generator target speed and the generator shaft speed;

[0114] The estimated torque of the engine is obtained according to the generator shift speed regulation torque, the generator output torque and a preset gear ratio.

[0115] In this embodiment, similar to the above, the direct drive gears include 1st gear, 2nd gear, 3rd gear and 4th gear. Each direct drive gear has a corresponding generator target speed. There is a process of changing from the power diversion gear to the direct drive gear, which lasts about 1.5-2 seconds. During this process, it is still considered to be in power diversion mode. In this process, the generator speed is adjusted to the target speed of the S2 synchronizer, and the speed of the S2 synchronizer is synchronized to the target speed, and the gear is engaged, so that the S2 synchronizer is engaged to the left side (that is, the planetary gear ring speed) or the right side (to 0) to complete the gear engagement. The final generator output torque T P1It is the sum of the engine power split balance negative torque (estimated torque of the engine) and the gear shift speed regulation torque based on the target speed difference of the generator for PID control. When the power split mode is in stable operation, the engine and the generator meet the above-mentioned torque relationship of the planetary gear power components. In addition, the generator gear shift speed regulation torque breaks the original balance stability, and the generator shaft speed changes to achieve speed regulation. The torque relationship between the engine and the generator can be expressed by the following formula:

[0116] T e =-(1+K)(T P1 -T P1Spd )

[0117] Among them, T e is the estimated torque of the engine, K is the gear ratio, T P1 is the output torque of the generator, T P1Spd Shift speed torque for the generator.

[0118] In summary, the above methods are respectively for estimating the engine torque under two working conditions: stable operation in power split mode and direct drive gear in power split mode. In order to ensure a smooth transition of torque, the estimated torque under the two working conditions can be controlled by a preset slope when switching. For example, a target rising slope is preset, and a target falling slope is preset. If the currently calculated estimated torque changes significantly compared to the last calculated estimated torque (for example, the rising slope is greater than the target rising slope, or the falling slope is less than the target falling slope), the preset target rising slope or target falling slope is used in combination with the estimated torque calculated last time to obtain the estimated torque for this time, which is used to replace the currently calculated estimated torque.

[0119] In addition, it should be noted that this embodiment also determines the validity of the engine estimated torque in the power split mode.

[0120] Considering that the vehicle may slip when encountering a low-adhesion road during driving, in the power split mode, the speed of the engine, generator and ring gear changes rapidly in a short period of time, so the calculated inertia torque of the engine and generator is quite different from the actual one. Therefore, in such working conditions, in order to avoid misjudgment of the authenticity of engine combustion, the estimated engine torque can be considered invalid. Specific steps may include:

[0121] Get the front wheel speed and rear wheel speed of the vehicle;

[0122] determining a wheel speed difference according to the front wheel speed and the rear wheel speed;

[0123] determining validity of the estimated torque according to the wheel speed difference;

[0124] If it is determined that the estimated torque is valid, the estimated torque of the engine is compared with a theoretical torque of the engine.

[0125] In this embodiment, the wheel speed difference between the driving wheel (front wheel) and the non-driving wheel (rear wheel) of the vehicle during driving is compared with the wheel speed threshold, and the frequent oscillation of the judgment result is effectively avoided by adding a hysteresis loop process for the vehicle speed difference. When the wheel speed difference is greater than the wheel speed threshold, it is considered that the vehicle is slipping, and the estimated torque is judged to be invalid; when the wheel speed difference is less than or equal to the wheel speed threshold, it is considered that the vehicle is not slipping, and the estimated torque is judged to be valid. At this time, the estimated torque of the engine can continue to be compared with the theoretical torque of the engine.

[0126] In summary, the embodiment of this specification provides a method for judging engine combustion, which obtains the theoretical torque of the engine, the output torque of the generator, the speed of the generator shaft, the speed of the engine shaft, the moment of inertia of the generator, and the moment of inertia of the engine in the engine power split mode; obtains the estimated torque of the engine according to the output torque of the generator, the speed of the generator shaft, the speed of the engine shaft, the moment of inertia of the generator, and the moment of inertia of the engine; compares the estimated torque of the engine with the theoretical torque of the engine, and judges whether the engine cylinder is truly burning according to the comparison result. In this way, by accurately and indirectly estimating the engine torque, the authenticity of the engine combustion can be effectively judged, and the reliable and safe operation of the vehicle can be guaranteed.

[0127] Based on the same inventive concept, Figure 4 As shown, an embodiment of the present invention further provides an engine combustion judgment device, comprising:

[0128] An acquisition module, used for acquiring the theoretical torque of the engine, the output torque of the generator, the generator shaft speed, the engine shaft speed, the rotational inertia of the generator and the rotational inertia of the engine in the engine power split mode;

[0129] a torque estimation module, configured to obtain an estimated torque of the engine according to the generator output torque, the generator shaft speed, the engine shaft speed, the generator moment of inertia, and the engine moment of inertia;

[0130] The judgment module is used to compare the estimated torque of the engine with the theoretical torque of the engine, and judge whether there is real combustion in the cylinder of the engine according to the comparison result.

[0131] Optionally, the torque estimation module is also used to:

[0132] Determining the inertia torque of the generator according to the generator shaft speed and the rotational inertia of the generator;

[0133] Determining the inertia torque of the engine according to the engine shaft speed and the rotational inertia of the engine;

[0134] The estimated torque of the engine is obtained according to the inertia torque of the generator, the inertia torque of the engine, the output torque of the generator and a preset gear ratio.

[0135] Optionally, the torque estimation module is also used to:

[0136] Obtaining an engine target speed corresponding to the power split gear position;

[0137] determining an inertia torque correction coefficient according to the target engine speed, the engine shaft speed, and the generator shaft speed;

[0138] According to the inertia torque correction coefficient, the inertia torque of the engine and the inertia torque of the generator are respectively corrected to obtain the corrected inertia torque of the engine and the corrected inertia torque of the generator;

[0139] The estimated torque of the engine is obtained according to the corrected inertia torque of the engine, the corrected inertia torque of the generator, the generator output torque, and the gear ratio.

[0140] Optionally, the torque estimation module is also used to:

[0141] Determining a speed difference according to the target engine speed and the engine shaft speed;

[0142] Determining a target angular acceleration according to the generator shaft speed and the engine shaft speed;

[0143] According to the speed difference and the target angular acceleration, the inertia torque correction coefficient is determined by searching in a preset correction coefficient table; the correction coefficient table includes a calibrated speed difference and a calibrated angular acceleration, and the correction coefficient table also includes a calibrated correction coefficient corresponding to the calibrated speed difference and the calibrated angular acceleration.

[0144] Optionally, the torque estimation module is also used to:

[0145] Obtaining a target speed of the generator corresponding to the direct drive gear;

[0146] Determining the generator shift speed regulating torque according to the generator target speed and the generator shaft speed;

[0147] The estimated torque of the engine is obtained according to the generator shift speed regulation torque, the generator output torque and a preset gear ratio.

[0148] Optionally, the acquisition module is also used to:

[0149] If the engine shaft speed is greater than the speed threshold, after a preset time, it is determined to be in the engine power split mode;

[0150] In the engine power split mode, the theoretical torque of the engine, the output torque of the generator, the generator shaft speed, the engine shaft speed, the rotational inertia of the generator and the rotational inertia of the engine are obtained.

[0151] Optionally, the judgment module is also used to:

[0152] Get the front wheel speed and rear wheel speed of the vehicle;

[0153] determining a wheel speed difference according to the front wheel speed and the rear wheel speed;

[0154] determining validity of the estimated torque according to the wheel speed difference;

[0155] If it is determined that the estimated torque is valid, the estimated torque of the engine is compared with a theoretical torque of the engine.

[0156] Optionally, the judgment module is also used to:

[0157] If the difference between the theoretical torque of the engine and the estimated torque of the engine is greater than a target threshold, it is determined that combustion in the cylinder of the engine has failed;

[0158] If the difference between the theoretical torque of the engine and the estimated torque of the engine is less than or equal to the target threshold, it is determined that real combustion occurs in the cylinder of the engine.

[0159] In summary, the engine combustion judgment device provided in the embodiment of this specification obtains the theoretical torque of the engine, the output torque of the generator, the generator shaft speed, the engine shaft speed, the rotational inertia of the generator, and the rotational inertia of the engine in the engine power diversion mode; obtains the estimated torque of the engine according to the output torque of the generator, the generator shaft speed, the engine shaft speed, the rotational inertia of the generator, and the rotational inertia of the engine; compares the estimated torque of the engine with the theoretical torque of the engine, and judges whether the engine cylinder is truly burning according to the comparison result. In this way, by accurately and indirectly estimating the engine torque, the authenticity of the engine combustion can be effectively judged, and the reliable and safe operation of the vehicle can be guaranteed.

[0160] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the engine combustion judgment device described above can refer to the corresponding process in the aforementioned method, and will not be elaborated here.

[0161] The above are only various embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for determining engine combustion, characterized in that: Applied to hybrid vehicles; The method comprises: In the engine power split mode, the theoretical torque of the engine, the output torque of the generator, the generator shaft speed, the engine shaft speed, the rotational inertia of the generator and the rotational inertia of the engine are obtained; Obtaining an estimated torque of the engine according to the generator output torque, the generator shaft speed, the engine shaft speed, the rotational inertia of the generator and the rotational inertia of the engine; The estimated torque of the engine is compared with the theoretical torque of the engine, and whether combustion is actually occurring in the cylinder of the engine is determined based on the comparison result.

2. The method according to claim 1, characterized in that The step of obtaining the estimated torque of the engine according to the generator output torque, the generator shaft speed, the engine shaft speed, the rotational inertia of the generator and the rotational inertia of the engine includes: Get the gear status of the hybrid vehicle; If the gear state is the power split gear, the estimated torque of the engine is obtained according to the generator output torque, the generator shaft speed, the engine shaft speed, the rotational inertia of the generator and the rotational inertia of the engine; If the gear state is the direct drive gear, then in the process of changing from the power split gear to the direct drive gear, the estimated torque of the engine is obtained according to the generator output torque and the generator shaft speed.

3. The method according to claim 2, characterized in that The step of obtaining the estimated torque of the engine according to the generator output torque, the generator shaft speed, the engine shaft speed, the rotational inertia of the generator and the rotational inertia of the engine includes: Determining the inertia torque of the generator according to the generator shaft speed and the rotational inertia of the generator; Determining the inertia torque of the engine according to the engine shaft speed and the rotational inertia of the engine; The estimated torque of the engine is obtained according to the inertia torque of the generator, the inertia torque of the engine, the output torque of the generator and a preset gear ratio.

4. The method according to claim 3, characterized in that: The step of obtaining the estimated torque of the engine according to the inertia torque of the generator, the inertia torque of the engine, the output torque of the generator and a preset gear ratio includes: Obtaining the target engine speed corresponding to the power split gear position; determining an inertia torque correction coefficient according to the target engine speed, the engine shaft speed, and the generator shaft speed; According to the inertia torque correction coefficient, the inertia torque of the engine and the inertia torque of the generator are respectively corrected to obtain the corrected inertia torque of the engine and the corrected inertia torque of the generator; The estimated torque of the engine is obtained according to the corrected inertia torque of the engine, the corrected inertia torque of the generator, the generator output torque, and the gear ratio.

5. The method according to claim 3, characterized in that: The determining of the inertia torque correction coefficient according to the target engine speed, the engine shaft speed and the generator shaft speed comprises: Determining a speed difference according to the target engine speed and the engine shaft speed; Determining a target angular acceleration according to the generator shaft speed and the engine shaft speed; According to the speed difference and the target angular acceleration, the inertia torque correction coefficient is determined by searching in a preset correction coefficient table; the correction coefficient table includes a calibrated speed difference and a calibrated angular acceleration, and the correction coefficient table also includes a calibrated correction coefficient corresponding to the calibrated speed difference and the calibrated angular acceleration.

6. The method according to claim 2, characterized in that The step of obtaining the estimated torque of the engine according to the generator output torque and the generator shaft speed includes: Obtaining a target speed of the generator corresponding to the direct drive gear; Determining the generator shift speed regulating torque according to the generator target speed and the generator shaft speed; The estimated torque of the engine is obtained according to the generator shift speed regulation torque, the generator output torque and a preset gear ratio.

7. The method according to claim 1, characterized in that The method of obtaining the theoretical torque of the engine, the output torque of the generator, the rotation speed of the generator shaft, the rotation speed of the engine shaft, the rotation inertia of the generator, and the rotation inertia of the engine in the engine power split mode includes: If the engine shaft speed is greater than the speed threshold, after a preset time, it is determined to be in the engine power split mode; In the engine power split mode, the theoretical torque of the engine, the output torque of the generator, the generator shaft speed, the engine shaft speed, the rotational inertia of the generator and the rotational inertia of the engine are obtained.

8. The method according to claim 1, characterized in that The comparing the estimated torque of the engine with the theoretical torque of the engine comprises: Get the front wheel speed and rear wheel speed of the vehicle; determining a wheel speed difference according to the front wheel speed and the rear wheel speed; determining validity of the estimated torque according to the wheel speed difference; If it is determined that the estimated torque is valid, the estimated torque of the engine is compared with a theoretical torque of the engine.

9. The method according to claim 1, characterized in that: The method further comprises: If the difference between the theoretical torque of the engine and the estimated torque of the engine is greater than a target threshold, it is determined that combustion in the cylinder of the engine has failed; If the difference between the theoretical torque of the engine and the estimated torque of the engine is less than or equal to the target threshold, it is determined that real combustion occurs in the cylinder of the engine.

10. An engine combustion judgment device, characterized in that: include: An acquisition module, used for acquiring the theoretical torque of the engine, the output torque of the generator, the generator shaft speed, the engine shaft speed, the rotational inertia of the generator and the rotational inertia of the engine in the engine power split mode; a torque estimation target torque, for obtaining an estimated torque of the engine according to the generator output torque, the generator shaft speed, the engine shaft speed, the generator moment of inertia and the engine moment of inertia; The judgment module is used to compare the estimated torque of the engine with the theoretical torque of the engine, and judge whether there is real combustion in the cylinder of the engine according to the comparison result.

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