Engine speed estimation method

Abstract

The present invention provides an engine speed estimation method, comprising the following steps: S1: in the current code operation cycle, according to the difference and time difference between the two nearest collected actual measurement values ​​of the engine speed, obtain a rough value of the speed change rate. S2: according to the correction coefficient of the speed change rate, correct the rough value of the speed change rate from the current moment to the moment when the actual measurement value of the engine speed is collected next time, and obtain a speed change rate correction value. S3: according to the actual measurement value of the engine speed collected closest to the current moment and the speed change rate correction value, estimate the current engine speed estimate. This method can estimate the engine speed and the engine speed change rate, can accurately reflect the actual situation of the engine speed and the speed change rate, and can be used for precise control of anti-stall at low speed.

Description

Technical Field

[0001] The invention relates to the field of automobiles, and in particular to a method for estimating engine speed. Background Art

[0002] DCT is an automatic dual-clutch transmission, which has been increasingly favored by domestic and foreign automobile OEMs in recent years. Compared with other automatic transmissions, DCT has the advantages of uninterrupted power during the gear shifting process and low fuel consumption, so it is one of the current popular automatic transmissions for automobiles. It is not only widely used in traditional internal combustion engine vehicles, but also in hybrid vehicles under various structural types. Therefore, the development of DCT control system is particularly important.

[0003] The engine anti-stall control is an important function of the automatic clutch controller. Its main control strategy is to detect when the engine speed is about to drop below the idle speed and cause the engine to stall, and control the clutch to open in advance to prevent the engine speed from further dropping to the point of stalling. In the engine anti-stall control strategy, the current engine speed and the engine speed change rate are key variables, and the timeliness and accuracy of the engine speed and speed change rate updates are crucial.

[0004] However, when the engine speed is too low, the engine speed is updated slowly due to the limitations of the accuracy and resolution of the engine speed sensor. The engine speed change rate calculated from the engine speed is delayed, resulting in delays in anti-stall control. In extreme cases, engine stalling cannot be avoided.

[0005] The general methods for calculating engine speed include M method, T method and M / T method. M method is to count the number of encoder pulses within a fixed time. Since the number of pulses in the measurement time decreases at low speed and the quantization error increases, M method is suitable for use at high speed. T method is to measure the time interval between two encoder pulses. Since the measured time interval decreases at high speed and the quantization error increases, T method is suitable for use at low speed. The traditional M / T method combines the advantages of M method and T method. In a relatively fixed time interval, the detection time and the number of encoder pulses within this time are measured at the same time. When the speed is high, the number of encoder pulses increases while the detection time remains basically unchanged, which is equivalent to M method and meets the speed measurement accuracy at high speed; when the speed is low, the number of encoder pulses decreases while the detection time increases, which is equivalent to T method and meets the speed measurement accuracy at low speed. Therefore, the traditional M / T speed measurement method can meet the speed measurement accuracy when the motor runs at medium and high speeds.

[0006] However, in the case of ultra-low speed, the encoder pulse interval exceeds the speed sampling period. The number of encoder pulses obtained in each speed sampling period is extremely small, or even less than one pulse. The speed detection stagnates at a certain speed value, leading to speed loss of control, low-speed oscillation, poor low-speed performance and other problems. Summary of the invention

[0007] In order to solve the technical problem of inaccurate low engine speed collection in the prior art, the purpose of the present invention is to provide a method for estimating engine speed, which estimates the engine speed and the engine speed change rate, can accurately reflect the actual situation of the engine speed and the speed change rate, and can be used for precise anti-stall control at low speed.

[0008] The present invention provides a method for estimating engine speed, comprising the following steps:

[0009] S1: In the current code running cycle, a rough value of the speed change rate is obtained according to the difference and time difference between the two nearest collected actual engine speed measurement values.

[0010] S2: Correcting the rough value of the speed change rate from the current moment to the moment when the actual engine speed measurement value is next collected according to the speed change rate correction coefficient to obtain a speed change rate correction value.

[0011] S3: estimating a current engine speed estimate value based on the actual engine speed measurement value and the speed change rate correction value collected most recently from the current moment.

[0012] By adopting the above scheme, it is possible to estimate the rough value of the current engine speed change rate based on the previous speed, and then correct the rough value of the speed change rate to the speed change rate correction value, so that on this basis, the current engine speed estimate value can be estimated based on the most recently collected speed measurement value, so that the engine speed collection is continuous and stable, avoiding the problem of speed value stagnation or collection interruption caused by a small number of pulses obtained within the sampling period. The engine speed estimation method provided by the present invention can accurately estimate the engine speed and speed change rate at low speeds, and the calculated engine speed can be highly matched with the actual speed. At the same time, the engine speed change rate obtained by this method can accurately reflect the actual situation of the current engine speed change rate compared to the original data. When used for anti-stall control, the engine anti-stall control timing can be quickly identified to effectively prevent the engine from stalling.

[0013] According to another specific embodiment of the present invention, an engine speed estimation method disclosed in an embodiment of the present invention further includes step S4 after step S3:

[0014] The anti-stall engine speed after the hydraulic response time is reached is obtained according to the current engine speed estimation value and the speed change rate correction value, and it is judged whether the anti-stall engine speed is lower than the preset first engine speed threshold. If so, the vehicle clutch is opened to activate the anti-stall strategy, and if the anti-stall engine speed increases to be greater than the preset second engine speed threshold, the anti-stall strategy is exited, wherein the second engine speed threshold is greater than the first engine speed threshold; if not, it is continued to judge whether the anti-stall engine speed is lower than the preset first engine speed threshold.

[0015] By adopting the above scheme, the anti-stall engine speed from the current moment to the hydraulic response time can be estimated according to the speed change rate correction value, and the anti-stall strategy start time can be identified in real time according to the anti-stall engine speed, and the engine anti-stall control time can be quickly identified, and the anti-stall control can be carried out in time at the current moment to effectively prevent the engine from stalling. That is to say, the engine speed calculated by the engine speed estimation method provided by the present invention can be highly matched with the actual speed, accurately reflecting the actual situation of the current engine speed change rate. When the engine speed is low, it can achieve the control goal of quickly and accurately identifying the anti-stall control time and opening the clutch to prevent the engine from stalling.

[0016] According to another specific embodiment of the present invention, an embodiment of the present invention discloses a method for estimating an engine speed, wherein the hydraulic response time is obtained by looking up a table based on the oil temperature and the current hydraulic position.

[0017] According to another specific embodiment of the present invention, an engine speed estimation method disclosed in an embodiment of the present invention further includes step S0 before step S1: monitoring the engine speed, and entering step S1 when the engine speed is lower than the ultra-low speed threshold.

[0018] By adopting the above scheme, by monitoring whether the engine speed reaches the ultra-low speed threshold, it is determined whether to enable the engine speed estimation method in this embodiment, which can not only ensure the operation of the existing anti-stall strategy but also avoid problems such as speed loss of control, low-speed oscillation, and poor low-speed performance at ultra-low speeds.

[0019] According to another specific embodiment of the present invention, an engine speed estimation method disclosed in an embodiment of the present invention further includes, after step S2, step S2-a: optimizing the correction coefficient to obtain an updated correction coefficient, and correcting the rough value of the speed change rate within the next actual speed change time according to the updated correction coefficient.

[0020] By adopting the above scheme, the correction coefficient is optimized to obtain an updated correction coefficient, so that the obtained rotation speed change rate correction value is more accurate.

[0021] According to another specific embodiment of the present invention, an engine speed estimation method disclosed in an embodiment of the present invention, in step S2-a, an actual engine speed measurement value is obtained, and an engine speed estimation value is obtained according to a speed change rate correction value. If the difference between the actual engine speed measurement value and the engine speed estimation value is greater than a preset correction threshold, the correction coefficient is reduced according to a preset correction ratio to obtain an updated correction coefficient; if the difference between the actual engine speed measurement value and the engine speed estimation value is less than or equal to the preset correction threshold, the correction coefficient is amplified according to a preset correction ratio to obtain an updated correction coefficient.

[0022] By adopting the above scheme, the correction coefficient is continuously optimized according to the difference between the actual measured value of the engine speed and the estimated value of the engine speed, so that the self-learning function of the correction coefficient can be realized, so that it can be continuously optimized and the accuracy can be improved, further accurately reflecting the actual situation of the engine speed and the speed change rate at low speed.

[0023] According to another specific embodiment of the present invention, an embodiment of the present invention discloses a method for estimating an engine speed, wherein an initial value of the correction coefficient is obtained by looking up a table based on the engine speed value.

[0024] According to another specific embodiment of the present invention, an engine speed estimation method disclosed in the embodiment of the present invention is applied to the transmission of an internal combustion engine vehicle and a hybrid vehicle.

[0025] According to another specific embodiment of the present invention, an embodiment of the present invention discloses a method for estimating an engine speed, wherein the transmission includes any one of a hydraulic automatic transmission, a dual clutch transmission and an electronically controlled mechanical automatic transmission.

[0026] The beneficial effects of the present invention are:

[0027] It is achieved that a rough value of the current engine speed change rate is estimated based on the previous speed, and then the rough value of the speed change rate is corrected to a speed change rate correction value, so that on this basis, the current engine speed estimate value can be estimated based on the most recently collected speed measurement value, so that the engine speed collection is continuous and stable, avoiding the problem of speed value stagnation or collection interruption caused by a small number of pulses obtained within the sampling period. The engine speed estimation method provided by the present invention can accurately estimate the engine speed and speed change rate at low speeds, and the calculated engine speed can be highly matched with the actual speed. At the same time, the engine speed change rate obtained by this method can accurately reflect the actual situation of the current engine speed change rate compared to the original data. When used for anti-stall control, the engine anti-stall control timing can be quickly identified to effectively prevent the engine from stalling. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1A control flow chart of an engine speed estimation method in one implementation of an embodiment of the present invention;

[0029] Figure 2 A schematic diagram of an engine speed estimation method of an engine speed estimation method in an implementation manner of an embodiment of the present invention;

[0030] Figure 3 A control flow chart of an engine speed estimation method in another implementation manner of an embodiment of the present invention;

[0031] Figure 4 A schematic diagram of identifying the timing of activating the anti-stall strategy in step S3 of a method for estimating engine speed in an implementation manner of an embodiment of the present invention;

[0032] Figure 5 A comparison diagram of the engine speed effect of anti-stall in a method for estimating engine speed in an implementation manner of an embodiment of the present invention;

[0033] Figure 6 This is a comparison diagram of the effect of the estimated engine speed change rate in a method for estimating engine speed in an implementation of an embodiment of the present invention. DETAILED DESCRIPTION

[0034] The following specific embodiments illustrate the implementation of the present invention, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Although the description of the present invention will be introduced in conjunction with the preferred embodiment, this does not mean that the features of this invention are limited to this implementation. On the contrary, the purpose of introducing the invention in conjunction with the implementation is to cover other options or modifications that may extend based on the claims of the present invention. In order to provide a deep understanding of the present invention, the following description will include many specific details. The present invention can also be implemented without using these details. In addition, in order to avoid confusion or blurring the focus of the present invention, some specific details will be omitted in the description. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0035] It should be noted that in this specification, similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0036] In the description of this embodiment, it should be noted that the terms "upper", "lower", "inner", "bottom", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the inventive product is usually placed when used. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0037] The terms “first”, “second”, etc. are only used for distinguishing descriptions and should not be understood as indicating or implying relative importance.

[0038] In the description of this embodiment, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "connected", and "connected" 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 components. For ordinary technicians in this field, the specific meanings of the above terms in this embodiment can be understood according to specific circumstances.

[0039] To make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0040] Example

[0041] A method for estimating engine speed, such as Figure 1 As shown, the following steps are included:

[0042] S1: In the current code running cycle, a rough value of the speed change rate is obtained according to the difference and time difference between the two nearest collected actual engine speed measurement values.

[0043] S2: Correcting the rough value of the speed change rate from the current moment to the moment when the actual engine speed measurement value is next collected according to the speed change rate correction coefficient to obtain a speed change rate correction value.

[0044] S3: estimating a current engine speed estimate value based on the actual engine speed measurement value and the speed change rate correction value collected most recently from the current moment.

[0045] Specifically, regarding steps S1-S3, an engine speed range of 200 rpm to 1200 rpm is used as an example for explanation. Figure 2 It is a principle diagram of the anti-stall engine speed in this speed range, wherein the ordinate Y-axis represents the engine speed value, and y1-y4 represent 4 data actually collected within the range of 200-1200rpm, and the abscissa T-axis represents time.

[0046] z is the current moment. When z=2, t1 and t2 are the two most recent engine speed change moments actually collected. t2-t3 is the time period for estimating the engine speed and speed change rate. Directly obtain the actual engine speed at t1 and t2, and then obtain the actual measured value difference (y2-y1) and time difference (t2-t1) of the engine speed at t1 and t2, and calculate the engine speed change rate in the interval [t1, t2] k1=(y2-y1) / (t2-t1), as follows: Figure 2 As shown by the dotted line t1-t2, extending k1 to t2-t3 gives Figure 2 The solid line k1 between t2 and t3.

[0047] Then, the speed change rate correction value k1'=k1*F in the interval (t2, t3] is calculated based on k1, such as Figure 2 The solid line k1' at t2-t3 in FIG. The correction coefficient F = f(EngSpd) can be obtained by looking up the table according to the engine speed value (EngSpd). Then, the speed estimation value at the corresponding moment can be obtained according to k1' and time.

[0048] For example, the estimated speed value y' at (t2, t3] is y'=k1'*(t-t2)+y2, where k1' is only used to estimate the engine speed in the time period (t2, t3). If there is no earlier data for calculation in the time period [t1, t2), the y1 value is maintained in the time period [t1, t2), and the actual value of y2 is at time t2.

[0049] When estimating the engine speed corresponding to the hydraulic response time, the hydraulic response time is substituted into the engine speed change rate of the current code operation cycle.

[0050] The above process is updated in real time, and a new engine speed change rate will be obtained after entering the next code operation cycle. That is, when z=3, the current moment enters t3, and the current code operation cycle becomes t3-t4, k2 and k2' of the code operation cycle can be obtained, and then y'=k2'*(t-t3)+y3 can be obtained, and then the same will continue as time goes by.

[0051] The code running cycle, that is, the operation cycle of the method for estimating the engine speed once, can be selected by technicians in this field by evaluating the size of the controller chip storage unit and the function priority, such as 10ms or 20ms, and this embodiment does not make any specific limitation.

[0052] By adopting the above scheme, it is possible to estimate the rough value of the current engine speed change rate based on the previous speed, and then correct the rough value of the speed change rate to the speed change rate correction value, so that on this basis, the current engine speed estimate value can be estimated based on the most recently collected speed measurement value, so that the engine speed collection is continuous and stable, avoiding the problem of speed value stagnation or collection interruption caused by a small number of pulses obtained within the sampling period. The engine speed estimation method provided by the present invention can accurately estimate the engine speed and speed change rate at low speeds, and the calculated engine speed can be highly matched with the actual speed. At the same time, the engine speed change rate obtained by this method can accurately reflect the actual situation of the current engine speed change rate compared to the original data. When used for anti-stall control, the engine anti-stall control timing can be quickly identified to effectively prevent the engine from stalling.

[0053] Furthermore, if Figure 1 As shown, after step S3, step S4 is also included: according to the current engine speed estimation value and the speed change rate correction value, the anti-stall engine speed after the hydraulic response time is reached is obtained, and whether the anti-stall engine speed is lower than the preset first engine speed threshold is judged. If so, the vehicle clutch is opened to activate the anti-stall strategy, and if the anti-stall engine speed increases to be greater than the preset second engine speed threshold, the anti-stall strategy is exited, wherein the second engine speed threshold is greater than the first engine speed threshold; if not, it continues to judge whether the anti-stall engine speed is lower than the preset first engine speed threshold.

[0054] Specifically, step S4 is used to identify the anti-stall control timing, that is, based on the speed change rate correction value and the hydraulic response time of the current code operation cycle, the anti-stall engine speed after the hydraulic response time is reached is estimated to identify the anti-stall control timing:

[0055] EngSpdCmp=EngineAccel*DetTm(OilTemp,Pstn)+EngSpdpst

[0056] Wherein, EngSpdCmp represents the anti-stall engine speed; EngineAccel represents the engine speed change rate; DetTm(OilTemp,Pstn) represents the hydraulic response time, and EngSpdpst represents the current engine speed.

[0057] The anti-stall engine speed refers to the engine speed after a period of time (hydraulic response time) from the current moment estimated by the current code operation cycle. Whether there is a risk of engine stalling is determined based on whether the speed is lower than the idle speed. The hydraulic response time refers to the time from the clutch opening command to the clutch fully opening and the hydraulic pressure pushing the clutch action.

[0058] The first engine speed threshold and the second engine speed threshold are the basis for judging the activation and exit of the anti-stall strategy. Figure 4 As shown in the figure, EngSpdLimtLo is the first engine speed threshold, EngSpdLimtHi is the second engine speed threshold, AntiStall_Flag=1 represents the clutch is open, and when AntiStall_Flag=0 represents normal clutch control at this time.

[0059] That is to say, when the anti-stall engine speed (EngSpdCmp) is less than the first engine speed threshold (EngSpdLimtLo), it means that the engine speed is about to be lower than the engine idle speed, and there is a risk of the speed continuing to drop and the engine stalling. At this time, the anti-stall strategy needs to be activated (flag AntiStall_Flag = 1). When the anti-stall engine speed (EngSpdCmp) is greater than the second engine speed threshold (EngSpdLimtHi), it means that the possibility of the engine stalling caused by the engine speed is small, AntiStall_Flag = 0, and the anti-stall strategy can be exited to perform normal clutch control.

[0060] The first engine speed threshold may be the speed at engine idle or the engine speed at which the engine is prone to stall near engine idle, and may be selected based on experimental experience or actual engine configuration. The second engine speed threshold may be an interval value set on the basis of the first engine speed threshold to prevent frequent activation of the anti-stall strategy, so as to accommodate some speed deviations, and may be obtained by those skilled in the art based on experimental experience.

[0061] It should be understood that the lower the speed, the easier it is for the encoder pulse interval to exceed the speed sampling period, and the fewer encoder pulses are obtained in each speed sampling period. Those skilled in the art can determine the first engine speed threshold according to actual needs. Under such a premise, preferably the first engine speed threshold can be a value within the range of 1200 revolutions or less, and more preferably 600 to 750 revolutions.

[0062] By adopting the above scheme, the anti-stall engine speed from the current moment to the hydraulic response time can be estimated according to the speed change rate correction value, and the anti-stall strategy start time can be identified in real time according to the anti-stall engine speed, and the engine anti-stall control time can be quickly identified, and the anti-stall control can be carried out in time at the current moment to effectively prevent the engine from stalling. That is to say, the engine speed calculated by the engine speed estimation method provided by the present invention can be highly matched with the actual speed, accurately reflecting the actual situation of the current engine speed change rate. When the engine speed is low, it can achieve the control goal of quickly and accurately identifying the anti-stall control time and opening the clutch to prevent the engine from stalling.

[0063] According to another specific embodiment of the present invention, an embodiment of the present invention discloses a method for estimating an engine speed, wherein the hydraulic response time is obtained by looking up a table based on the oil temperature and the current hydraulic position.

[0064] Specifically, the oil temperature and current hydraulic position table lookup contents may be determined through experimental experience or theoretical calculation.

[0065] According to another specific embodiment of the present invention, an engine speed estimation method disclosed in an embodiment of the present invention further includes step S0 before step S1: monitoring the engine speed, and entering step S1 when the engine speed is lower than the ultra-low speed threshold.

[0066] It should be understood that the lower the speed, the easier it is for the encoder pulse interval to exceed the speed sampling period, and the fewer encoder pulses are obtained in each speed sampling period. The performance of various engines in shutting down at low speeds is also different. Technical personnel in this field can determine the ultra-low speed threshold of the starting step S1 based on the actual engine performance.

[0067] In this embodiment, the ultra-low speed threshold may be 1200 rpm and a value within a certain deviation range thereof, and more preferably may be 600-750 rpm.

[0068] By adopting the above scheme, by monitoring whether the engine speed reaches the ultra-low speed threshold, it is determined whether to enable the engine speed estimation method in this embodiment, which can not only ensure the operation of the existing anti-stall strategy but also avoid problems such as speed loss of control, low-speed oscillation, and poor low-speed performance at ultra-low speeds.

[0069] According to another specific embodiment of the present invention, an engine speed estimation method disclosed in an embodiment of the present invention is as follows: Figure 3 As shown, after step S2, step S2-a is also included: optimizing the correction coefficient to obtain an updated correction coefficient, and correcting the rough value of the speed change rate within the next actual speed change time according to the updated correction coefficient.

[0070] By adopting the above scheme, the correction coefficient is optimized to obtain an updated correction coefficient, so that the obtained rotation speed change rate correction value is more accurate.

[0071] According to another specific embodiment of the present invention, an engine speed estimation method disclosed in an embodiment of the present invention is as follows: Figure 3As shown, in step S2-a, the actual measured value of the engine speed is obtained, and the estimated value of the engine speed is obtained according to the speed change rate correction value. If the difference between the actual measured value of the engine speed and the estimated value of the engine speed is greater than a preset correction threshold, the correction coefficient is reduced according to a preset correction ratio to obtain an updated correction coefficient; if the difference between the actual measured value of the engine speed and the estimated value of the engine speed is less than or equal to the preset correction threshold, the correction coefficient is enlarged according to a preset correction ratio to obtain an updated correction coefficient.

[0072] Specifically, the correction coefficient is updated based on the difference between the actual measured value and the estimated value of the engine speed and the correction threshold value. The updated correction coefficient will not be used for the calculation of this code operation cycle, but for the calculation cycle of the next engine speed estimation method.

[0073] With the above Figure 2 The current time is t2, and the prediction algorithm starts from t1. Figure 2 Where y1, y2, and y3 are actual measured values ​​of the actual engine speed.

[0074] It should be understood that starting from t1, the estimation algorithm cannot estimate y1' and y2', k1' can only estimate the speed in the time period (t2, t3], and k2' is only used to estimate the speed in the time period (t3, t4], and so on.

[0075] Use the speed change rate correction value of the current code operation cycle to calculate the estimated engine speed at a certain moment in the previous code operation cycle, and then obtain the actual measured engine speed at that moment in the previous code operation cycle, and compare the difference between the estimated engine speed and the actual measured engine speed with the preset correction threshold, that is, compare the difference between y3' and y3 with the preset correction threshold.

[0076] The correction ratio can be obtained according to the value self-search function, and the computer is first used to adjust it at a larger ratio, and then a smaller ratio is used to adjust it after the adjustment effect is stable, so as to obtain a correction ratio with less fluctuation and more accuracy. Those skilled in the art can also set it according to the empirical value obtained from the test data, and this embodiment is not specifically limited here. The correction threshold can be selected according to the actual manufacturing design process level and accuracy, and this embodiment is not specifically limited here.

[0077] By adopting the above scheme, the correction coefficient is continuously optimized according to the difference between the actual measured value of the engine speed and the estimated value of the engine speed, so that the self-learning function of the correction coefficient can be realized, so that it can be continuously optimized and the accuracy can be improved, further accurately reflecting the actual situation of the engine speed and the speed change rate at low speed.

[0078] According to another specific embodiment of the present invention, an engine speed estimation method disclosed in an embodiment of the present invention is as follows: Figure 3 As shown, the initial value of the correction coefficient is obtained by looking up the table according to the engine speed value.

[0079] Specifically, the engine speed value lookup table content can be determined through experimental experience or theoretical calculation.

[0080] According to another specific embodiment of the present invention, an engine speed estimation method disclosed in the embodiment of the present invention is applied to the transmission of an internal combustion engine vehicle and a hybrid vehicle.

[0081] According to another specific embodiment of the present invention, an embodiment of the present invention discloses a method for estimating an engine speed, wherein the transmission includes any one of a hydraulic automatic transmission, a dual clutch transmission and an electronically controlled mechanical automatic transmission.

[0082] Experimental results in the embodiments of the present invention:

[0083] Figure 5 It is a comparison chart of the original engine speed (EngineSpeedRaw) of the actual vehicle data and the real-time engine speed estimation value (EngineSpeedEstd) calculated by the above method in this embodiment.

[0084] Figure 6 It is a comparison diagram of the engine speed change rate (EngineAccelRaw) calculated from the original engine speed (EngineSpeedRaw) in the prior art and the engine speed change rate (EngineAccelEstd) calculated by the above method in this embodiment.

[0085] pass Figure 5 and Figure 6 It can be seen from the test data that the engine speed calculated by the engine speed estimation method provided by the present invention can highly match the actual speed. At the same time, the engine speed change rate (EngineAccelEstd) obtained by this method can accurately reflect the actual situation of the current engine speed change rate compared with the method of only collecting original data in the prior art. When the engine speed is low, by estimating the current engine speed change rate and the actual measured value of the engine speed, it is possible to quickly and accurately identify the anti-stall control opportunity and open the clutch to prevent the engine from stalling.

[0086] Although the present invention has been illustrated and described with reference to certain preferred embodiments of the present invention, it should be understood by those skilled in the art that the above is a further detailed description of the present invention in conjunction with specific embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. Those skilled in the art may make various changes in form and details, including making several simple deductions or substitutions, without departing from the spirit and scope of the present invention.

Claims

1. A method for estimating engine speed, characterized in that: The following steps are involved: S1: In the current code running cycle, a rough value of the speed change rate is obtained according to the difference and time difference between the two nearest collected actual engine speed measurement values; S2: Correcting the rough value of the speed change rate from the current moment to the moment when the actual engine speed measurement value is next collected according to the speed change rate correction coefficient to obtain a speed change rate correction value; S3: estimating a current engine speed estimate value based on the actual engine speed measurement value collected most recently from the current moment and the speed change rate correction value.

2. The method for estimating engine speed according to claim 1, characterized in that: After step S3, the method further includes the following steps: S4: obtaining the anti-stall engine speed after the hydraulic response time is reached according to the current engine speed estimation value and the speed change rate correction value, and determining whether the anti-stall engine speed is lower than a preset first engine speed threshold; If so, opening the vehicle clutch to activate the anti-stall strategy, and if the anti-stall engine speed increases to be greater than a preset second engine speed threshold, exiting the anti-stall strategy, wherein the second engine speed threshold is greater than the first engine speed threshold; If not, continue to determine whether the anti-stall engine speed is lower than the preset first engine speed threshold.

3. The method for estimating engine speed according to claim 2, characterized in that: The hydraulic response time is obtained by looking up a table based on the oil temperature and the current hydraulic position.

4. The method for estimating engine speed according to claim 1, characterized in that: Before step S1, the method further includes the following steps: S0: monitor the engine speed, and when the engine speed is lower than the ultra-low speed threshold, enter step S1.

5. The method for estimating engine speed according to claim 4, characterized in that: After step S2, the method further includes the following steps: S2-a: Optimizing the correction coefficient to obtain an updated correction coefficient, and correcting the rough value of the speed change rate within the next actual speed change time according to the updated correction coefficient.

6. The method for estimating the engine speed according to claim 5, characterized in that: In the step S2-a, an actual measured value of the engine speed is obtained, and an estimated value of the engine speed is obtained according to the speed change rate correction value; If the difference between the actual measured value of the engine speed and the estimated value of the engine speed is greater than a preset correction threshold, reducing the correction coefficient according to a preset correction ratio to obtain the updated correction coefficient; If the difference between the actual measured value of the engine speed and the estimated value of the engine speed is less than or equal to a preset correction threshold, the correction coefficient is amplified according to a preset correction ratio to obtain the updated correction coefficient.

7. The method for estimating engine speed according to claim 5, characterized in that: The initial value of the correction coefficient is obtained by looking up the table according to the engine speed value.

8. The method for estimating the engine speed according to any one of claims 1 to 7, characterized in that: Transmissions for internal combustion engine vehicles and hybrid vehicles.

9. The method for estimating engine speed according to claim 8, characterized in that: The transmission includes any one of a hydraulic automatic transmission, a dual clutch transmission and an electronically controlled mechanical automatic transmission.

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