Predictive torque management method and device and vehicle

Abstract

The invention relates to a predictive torque management method comprising the following steps: selecting a torque range having an upper boundary torque and a lower boundary torque, the upper boundary torque being selected to be higher than an optimal torque and / or the lower boundary torque being selected to be lower than the optimal torque, the optimal torque is the torque with the lowest oil consumption at a certain engine rotating speed during engine operation; and performing engine torque limiting based on the torque range wherein the engine torque is limited to an upper boundary torque when the torque demand exceeds the upper boundary torque; the engine torque is limited to zero when the torque demand is below the lower boundary torque.

Description

Predictive torque management method, device and vehicle Technical Field

[0001] The present invention relates to a predictive torque management method and device. Background Art

[0002] In the field of transportation, there is an increasing need to improve vehicle fuel efficiency, save energy and reduce emissions. For this purpose, Predictive Economic Cruise Control (PECC) can be used. For example, ZF's predictive adaptive cruise control system OptiPace TM Based on cruise control and positioning information, the system automatically optimizes vehicle speed based on the terrain and conditions of the road ahead, thereby reducing fuel consumption and improving operational efficiency. The vehicle's positioning system utilizes GNSS (Global Navigation Satellite System) for positioning. This GNSS-derived positioning information is matched with the ADAS map to confirm the vehicle's position and, in turn, to obtain road information. The OptiPace system then optimizes vehicle speed and coordinates the vehicle's actuator systems accordingly based on this road information.

[0003] OptiPace TM The Predictive Torque Management (PTM) module (PECC) reshapes the local torque curve to achieve better fuel efficiency. In the original PTM, high torque is limited when the air-fuel ratio (AFR) is uneconomical. Specifically, at a given engine speed, when the instantaneous AFR falls below a certain value in the lookup table (optimal AFR), the ramp from low torque to high torque is limited in terms of gradient and even the target of the immediate ramp to immediately increase the AFR. This allows the AFR to return above the optimal AFR, ensuring fuel efficiency. When PECC predicts low torque, PTM examines the proportion of the less-economical portion of the prediction range, as low torque is associated with high brake specific fuel consumption (BSFC), indicating poor economy. If the less-economical portion accounts for a significant proportion, the low torque within the prediction range is reduced to zero. Consequently, the proportion of medium- and high-torque values ​​corresponding to low BSFC is increased.

[0004] In the prior art, if BSFC / AFR efficiency remains poor for a sustained period, a single BSFC / AFR optimization is performed at each engine speed. Specifically, all high torque requests exceeding the torque corresponding to the optimal BSFC / AFR are limited to the torque corresponding to that optimal BSFC / AFR; while all low torque requests below the torque corresponding to the optimal BSFC / AFR are limited to 0 Nm.

[0005] However, this strategy relies on a single optimal AFR or BSFC. The consequences will be:

[0006] 1. High torque is overly limited: For example, the optimal AFR at 2000 Nm is 20, while the AFR at 2300 Nm is 20.05. The difference between the optimal AFR at 2000 Nm and the AFR at 2300 Nm is minimal. The existing technology only accepts the torque at the optimal AFR (2000 Nm) and rejects all other torques. This means that all other torque requests above the optimal AFR (2000 Nm) are limited to the optimal AFR (2000 Nm). Therefore, a torque request of 2400 Nm is limited to 2000 Nm. However, the difference between the AFRs of 2300 Nm and 2000 Nm is not significant. This indicates that this strategy only yields minimal fuel economy improvements, but significantly reduces torque. This reduction in torque results in reduced speed and increased driving time. Therefore, this strategy sacrifices vehicle speed without significantly improving fuel economy.

[0007] 2. Low-speed torque is overly limited: For example, at a certain engine speed, the optimal BSFC is 188.3 g / kWh at a torque of 2000 Nm. As the BSFC changes from 188.3 g / kWh to 188.5 g / kWh, the torque changes from 2000 Nm to 1000 Nm. However, below 1000 Nm, the BSFC increases dramatically. Under the original PTM strategy, all torque requests below the optimal BSFC (e.g., 2000 Nm), such as 1900 Nm and 100 Nm, are treated equally and set to 0 Nm, resulting in lower speeds and increased driving time. In reality, the BSFC corresponding to torques between 1900 Nm and 1000 Nm in the above example is not significantly different from the optimal BSFC of 188.3 g / kWh. However, in the prior art, this portion of torque is discarded.

[0008] Summary of the Invention

[0009] In order to overcome the above shortcomings, an embodiment of the present invention provides a predictive torque management method, which can improve predictive torque management and improve the trade-off in the torque limit decision-making process so that the torque will not be over-limited.

[0010] To achieve the above objective, according to one aspect of an embodiment of the present invention, a predictive torque management method is provided, comprising the following steps: selecting a torque range having an upper boundary torque and a lower boundary torque, wherein the upper boundary torque is selected to be higher than an optimal torque and / or the lower boundary torque is selected to be lower than the optimal torque, wherein the optimal torque is the torque with the lowest fuel consumption at a certain engine speed during engine operation; and

[0011] The engine torque is limited based on the torque range, wherein when the torque demand exceeds an upper torque limit, the engine torque is limited to the upper torque limit; and when the torque demand is lower than a lower torque limit, the engine torque is limited to zero.

[0012] The torque range selected according to the method of the present invention achieves optimal fuel efficiency during engine operation. This torque range corresponds to a range of operating parameters that provides an economical band for achieving optimal fuel efficiency. This optimal fuel efficiency is comparable to the optimal fuel efficiency (lowest fuel consumption) and fully utilizes the torque near the engine's optimal torque.

[0013] Because an economic band (i.e., a certain range of values) is used instead of a single value as a criterion, the predictive torque management of the present invention achieves the following advantages:

[0014] 1. There are fewer interruptions when executing the optimized curves of speed and torque of the PECC plan, so the consumption of computing resources and the re-optimization of PECC predictions that lead to inconsistent plans can be minimized.

[0015] 2. Torque limitation occurs less frequently, so most of the planned torque can be maintained and the increase in travel time can be reduced.

[0016] According to a preferred embodiment of the present invention, a torque range is selected based on the values ​​of engine operating parameters. The optimal operating parameter value that minimizes fuel consumption at a certain engine speed is determined, and the operating parameter boundary value is set to the sum of the optimal operating parameter value and an operating parameter threshold. The upper and / or lower torque boundary values ​​are determined based on the operating parameter boundary value. At each engine speed, the operating parameter varies with torque. For a specific engine speed, the minimum value of the operating parameter at that engine speed can be used as the optimal operating parameter value.

[0017] According to a preferred embodiment of the present invention, optimal operating parameters of the engine are first determined. For example, optimal operating parameters, such as optimal effective fuel consumption or optimal air-fuel ratio, can be determined from an engine map (i.e., a universal characteristic map) or through road testing. At each engine speed, the effective fuel consumption / air-fuel ratio varies with torque, with the minimum value representing the optimal effective fuel consumption / or optimal air-fuel ratio.

[0018] An economy band is then generated based on the learned optimal operating parameter value. For example, an operating parameter threshold can be selected for this purpose. Based on the optimal operating parameter value and the operating parameter threshold, an operating parameter range is selected from the optimal operating parameter value to the sum of the optimal operating parameter value and the operating parameter threshold. When the operating parameter is the effective fuel consumption rate, the economy band can be selected based on the effective fuel consumption rate range from the optimal effective fuel consumption rate to the sum of the optimal effective fuel consumption rate and the effective fuel consumption rate threshold. When the operating parameter is the air-fuel ratio, the economy band can be selected based on the air-fuel ratio range from the optimal air-fuel ratio to the sum of the optimal air-fuel ratio and the air-fuel ratio threshold.

[0019] After the optimal operating parameter value is known, the operating parameter boundary value can be set to the sum of the optimal operating parameter value and an operating parameter threshold. Then, the lower torque corresponding to the operating parameter boundary value and lower than the optimal torque is recorded as the lower boundary torque.

[0020] If a corresponding upper torque higher than the optimal torque can be found at the operating parameter boundary value in the engine map or the operating parameter and torque lookup table, this corresponding upper torque is recorded as the upper boundary torque; otherwise, the maximum torque that the engine can provide is used as the upper boundary torque.

[0021] Alternatively, the economic zone may be generated based on the gradient of an operating parameter. For example, the effective fuel consumption rate or the air-fuel ratio may be selected as the operating parameter, and the economic zone may be generated based on the effective fuel consumption rate gradient or the air-fuel ratio gradient.

[0022] In the case of generating an economic band based on a gradient, a torque range is selected based on the gradient of the engine's operating parameters changing with torque, wherein the gradient of the operating parameters is generated based on the difference between the operating parameter values ​​corresponding to adjacent torques; a certain gradient threshold is selected; the gradient of the operating parameters is compared with the gradient threshold, and the upper boundary torque and / or the lower boundary torque is determined based on the comparison.

[0023] When the gradient is lower than the negative gradient threshold, the lower boundary of the operating parameter is selected. At this time, the corresponding torque is used as the lower boundary torque.

[0024] When the gradient exceeds the positive gradient threshold, the upper boundary of the operating parameter is selected. If a corresponding torque can be found at the upper boundary of the operating parameter, it is used as the upper boundary torque. If no torque that satisfies the gradient requirement of exceeding the positive gradient threshold is found, the maximum torque that the engine can provide is used as the upper boundary torque.

[0025] In another preferred embodiment, the economic band is generated using a clustering method at each engine speed.

[0026] According to an embodiment of the present invention, clusters of the operating parameter data can be obtained based on cluster analysis of the engine operating parameter data, thereby selecting a torque range corresponding to the cluster, wherein:

[0027] A clustering index is set, and data of operating parameters that meet the clustering index compared with the optimal operating parameter value corresponding to the optimal torque are selected into a cluster cluster using a clustering method;

[0028] Obtaining operating parameter boundary values ​​based on the data boundaries of the clusters; and

[0029] An upper limit torque and / or a lower limit torque is determined based on the operating parameter limit values.

[0030] After the operating parameter boundary value is determined, a lower torque corresponding to the operating parameter boundary value and lower than the optimal torque may be recorded as the lower boundary torque.

[0031] In addition, if a corresponding upper torque higher than the optimal torque can be found at the operating parameter boundary value, the corresponding upper torque is recorded as the upper boundary torque; otherwise, the maximum torque that the engine can provide is used as the upper boundary torque.

[0032] The engine operating parameters that may be used in the present invention are the best-behaved fuel consumption (BSFC) or the air-fuel ratio (AFR). The optimal operating parameter value may be the best-behaved fuel consumption or the best-behaved air-fuel ratio. The economy band may cover a range of BSFC that includes the best-behaved fuel consumption, or a range of air-fuel ratios that includes the best-behaved air-fuel ratio.

[0033] After defining an economy band, torque can be limited based on the band. In Predictive Torque Management (PTM)'s "Upper Mode," torque requests exceeding the upper torque limit are limited to the upper torque limit. The upper torque limit is set to a value greater than the torque corresponding to the optimal fuel economy or air-fuel ratio, preventing excessive torque restriction at high speeds. Limitation may even be eliminated when the upper torque limit reaches the maximum torque.

[0034] Furthermore, in the "lower mode" of predictive torque management, torque requests below a lower torque limit can be limited to zero. By using the lower limit corresponding to the economy band, torque requests below the torque obtained from the optimal fuel consumption rate or the optimal air-fuel ratio but above the lower torque limit are not limited, while torque requests below the lower torque limit are limited to zero.

[0035] The present invention also proposes a predictive torque management device, which has a predictive torque management module. The predictive torque management module can implement the predictive torque management method of the present invention.

[0036] The present invention further provides a computer-readable medium having a computer program stored thereon. When the computer program is executed by a processor, the predictive torque management method according to the present invention is implemented.

[0037] The invention also relates to a vehicle equipped with a predictive torque management device according to the invention.

[0038] The above-mentioned non-conventional optional manner will be described below in conjunction with specific implementation methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The accompanying drawings are provided for a better understanding of the present invention and are not intended to limit the present invention.

[0040] FIG1 shows an engine diagram of an embodiment of the present invention;

[0041] FIG2 is a schematic diagram showing BSFC or AFR trends at a specific engine speed depicted in FIG1 according to an embodiment of the present invention;

[0042] FIG3 is a schematic diagram showing the gradient of BSFC or AFR distribution corresponding to a certain engine speed according to an embodiment of the present invention;

[0043] FIG4 shows a cluster diagram of BSFC or AFR distribution corresponding to a certain engine speed according to an embodiment of the present invention. DETAILED DESCRIPTION

[0044] The following description of exemplary embodiments of the present invention is made in conjunction with the accompanying drawings, in which various details of the embodiments of the present invention are included to facilitate understanding. These details should be considered as merely exemplary. Therefore, it should be appreciated by those skilled in the art that various changes and modifications may be made to the embodiments described herein without departing from the scope and spirit of the present invention. Similarly, for the sake of clarity and conciseness, descriptions of well-known functions and structures are omitted in the following description.

[0045] FIG1 illustrates a typical engine diagram according to an embodiment of the present invention. In FIG1 , the abscissa represents engine speed, the ordinate represents torque, and the effective fuel consumption (BSFC) is plotted as contour lines. The optimal BSFC or AFR line is plotted over a wide range of engine speeds, while the BSFC or AFR economic band is plotted only up to a certain engine speed.

[0046] According to a preferred embodiment of the present invention, the optimal BSFC or the optimal AFR is obtained in the first step. The optimal BSFC or the optimal AFR is a line on the engine map (as shown by the thick dotted line in FIG1 ).

[0047] At each engine speed, an optimal BSFC or an optimal AFR can be directly derived from the engine map. The optimal BSFC or the optimal AFR is also indicated in FIG2 , for example.

[0048] By connecting each optimal BSFC value at each engine speed and performing necessary interpolation, an optimal BSFC line or an optimal BSFC lookup table can be obtained. Regarding the optimal AFR, if the engine manufacturer provides AFR or equivalent air flow and fuel rate data in the engine map in the same manner as BSFC, an AFR table can be generated with engine speed and torque as the coordinates (similar to Figure 1, with AFR replacing BSFC). The subsequent steps are no different from those in the BSFC case. If the engine manufacturer does not provide AFR, an AFR table can be derived through independent calculation or self-learning to implement the method of the present invention.

[0049] In the second step, an economic band is generated according to the optimal BSFC or optimal AFR obtained previously.

[0050] FIG. 2 shows a BSFC or AFR trend diagram at a specific engine speed depicted in FIG. 1 , in which an optimal BSFC or AFR point and a BSFC or AFR economic band are plotted, according to an embodiment of the present invention.

[0051] At each engine speed, BSFC or AFR varies with torque. First, a minimum value, namely the optimal BSFC or optimal AFR, can be determined, as shown in Figure 2. According to an embodiment of the present invention, a BSFC threshold or an AFR threshold is selected, denoted as th BSFC or th AFR The BSFC threshold or AFR threshold can be defined empirically. Based on the optimal BSFC and BSFC threshold, the optimal BSFC is selected in [optimal BSFC, optimal BSFC+th BSFC ] range as the economic zone. Similarly, it is also possible to calculate the economic zone based on the optimal AFR and the AFR threshold th AFR , select [best AFR, best AFR+th AFR ]The belt within the range is regarded as the economic belt.

[0052] For example, when the engine speed is 1100 and the torque is 2200, the optimal BSFC is 188.0, and the BSFC threshold can be 0.5. Then the BSFC range is [188.0, 188.5], which can cover the torque range of [1500, 2750] in the entire torque range of [0, 2750]. The lower boundary is found at BSFC = 188.5, and the corresponding torque is recorded as 1500 as the lower boundary torque. If the upper boundary can be found at BSFC = 188.5, the corresponding torque is recorded as the upper boundary torque; otherwise, the maximum torque is used as the upper boundary torque, as in this example. The units of the various parameters in this embodiment are as follows: BSFC ~ g / kWh, engine speed ~ rpm, torque ~ Nm. By connecting and interpolating between engine speeds, an economic band can be defined, as shown in Figure 1.

[0053] As an alternative to the above threshold method, the gradient threshold method or clustering method can be used to generate economic zones.

[0054] Figure 3 shows a schematic diagram of the BSFC or AFR gradient corresponding to a specific engine speed, according to an embodiment of the present invention. The BSFC / AFR gradient measures how BSFC / AFR changes with torque. The BSFC / AFR gradient is the difference between BSFC / AFR values ​​corresponding to adjacent torques. At the optimal torque corresponding to optimal BSFC / AFR, the gradient is typically zero.

[0055] In a preferred embodiment of the present invention, the BSFC gradient threshold grad_th BSFC It can be used to find places where BSFC or BSFC gradient changes greatly with torque. BSFC Below the negative gradient threshold grad_th BSFC , that is, grad BSFC <-grad_th BSFC When , the lower boundary is selected and the corresponding torque is the lower boundary torque. BSFC , that is, grad BSFC >grad_th BSFC When the upper boundary is selected, the corresponding torque is the upper boundary torque. If no place can be found to meet the grad BSFC >grad_th BSFC If the condition is met, the maximum torque is used as the upper boundary torque. For AFR, a similar gradient threshold method can also be used.

[0056] Another improved method can utilize clustering to generate economy zones. Typical partitioning and density-based clustering methods, combined with appropriate criteria, can be used to address this type of clustering. The selected clusters can be shown in Figure 4 . Figure 4 illustrates a clustering diagram corresponding to BSFC or AFR distribution at a specific engine speed, according to an embodiment of the present invention.

[0057] For example, in density-based DBSCAN, the density index ε for AFR data can be set as low as 0.2. In a simplified and illustrative embodiment, the density index ε can be understood as a criterion for the difference between an AFR data point and the optimal AFR. When the difference between an AFR data point and the optimal AFR is less than or equal to ε, the AFR data point is selected into a cluster; otherwise, it is not selected. This may result in an effect similar to the AFR gradient threshold set to 0.2 in the previous method. Other clustering metrics can also be selected based on the selected clustering method, such as a clustering metric based on the squared difference between AFR data points. By comparing the data with the clustering metric, data that meets the clustering metric can be selected into clusters.

[0058] In the clustering method, the minimum number of samples can be set as low as 1, which means that at least the best point will be selected in the cluster as the economic zone. The economic zone / cluster has corresponding upper and lower boundary torques at the same value. If the minimum number of samples is 3, it means that at least 3 points will be selected. In extreme cases, the cluster obtained according to the method of the present invention may only contain the best AFR point. At this time, the upper and lower boundary torques are equal, equal to the best torque corresponding to the best AFR. Therefore, the method of the present invention is also compatible with torque optimization based on a single BSFC / AFR when generating the economic zone using the clustering method. Based on the density index ε and the minimum number of samples, a cluster can be selected from the AFR data as the economic zone, and the corresponding upper and lower boundary torques and the corresponding torque range can be obtained according to the data boundary value of the cluster. Here, for example, the upper and lower boundary torques can be determined by referring to the method mentioned in the above embodiment.

[0059] After the economic band is defined, torque limitation can be performed based on the economic band.

[0060] Generally, in the prior art, PTM uses an “upper mode” to limit high torque to an appropriate torque value based on optimal BSFC or optimal AFR, and uses a “lower mode” to limit low torque to zero.

[0061] According to the present invention, by using the BSFC / AFR economic band, an upper boundary torque corresponding to the BSFC / AFR boundary can be obtained. In the "upper mode", high torque requirements can be limited to the upper boundary torque, which is greater than the torque corresponding to the optimal BSFC or AFR, and no limitation is even implemented when the upper boundary reaches the maximum torque.

[0062] By using the lower boundary torque corresponding to the BSFC / AFR economy band boundary, torque requests that are lower than the torque resulting from the optimal BSFC or optimal AFR but higher than the lower boundary torque are not limited, while torque requests that are lower than the lower boundary torque are limited to zero.

[0063] Therefore, the limitation caused by PTM occurs less frequently in operating conditions where the economic benefit is less significant, or in other words, the torque reduction caused by PTM occurs less frequently in such operating conditions, so the planned speed profile can be better maintained and speed reduction occurs less frequently.

[0064] The above specific embodiments do not limit the scope of protection of the present invention. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions may occur depending on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention are intended to be included within the scope of protection of the present invention.

Claims

1. A predictive torque management method, characterized in that: The method comprises the following steps: selecting a torque range having an upper torque limit and a lower torque limit, wherein the upper torque limit is selected to be higher than an optimal torque and / or the lower torque limit is selected to be lower than an optimal torque, wherein the optimal torque is a torque that minimizes fuel consumption at a certain engine speed during engine operation; and The engine torque is limited based on the torque range, wherein when the torque demand exceeds an upper torque limit, the engine torque is limited to the upper torque limit; and when the torque demand is lower than a lower torque limit, the engine torque is limited to zero.

2. The method according to claim 1, characterized in that The torque range is selected based on the value of the engine's operating parameter, wherein an optimal operating parameter value with the lowest fuel consumption at a certain engine speed during engine operation is obtained, the operating parameter boundary value is set to the sum of the optimal operating parameter value and an operating parameter threshold value, and an upper boundary torque and / or a lower boundary torque is determined based on the operating parameter boundary value.

3. The method according to claim 2, characterized in that A lower torque below the optimal torque corresponding to the operating parameter boundary value is recorded as the lower boundary torque.

4. The method according to claim 2, characterized in that If a corresponding upper torque higher than the optimal torque can be found at the operating parameter boundary value, the corresponding upper torque is recorded as the upper boundary torque; otherwise, the maximum torque that the engine can provide is used as the upper boundary torque.

5. The method according to claim 1, wherein selecting a torque range based on a gradient of a change in an operating parameter of the engine with respect to torque, wherein the gradient of the operating parameter is generated based on a difference between operating parameter values ​​corresponding to adjacent torques; Select the gradient threshold; The gradient of the operating parameter is compared to a gradient threshold value, and an upper boundary torque and / or a lower boundary torque is determined based on the comparison.

6. The method according to claim 5, characterized in that When the gradient is lower than the negative gradient threshold, the lower limit of the operating parameter is selected and the corresponding torque is used as the lower limit torque.

7. The method according to claim 5, characterized in that When the gradient is higher than the positive gradient threshold, the upper boundary of the operating parameter is selected. If a corresponding torque can be found at the upper boundary of the operating parameter, the corresponding torque is used as the upper boundary torque. If a torque that satisfies the condition that the gradient is higher than the positive gradient threshold cannot be found, the maximum torque that the engine can provide is used as the upper boundary torque.

8. The method according to claim 1, characterized in that Based on cluster analysis of the engine's operating parameter data, clusters of the operating parameter data are obtained, thereby selecting a torque range corresponding to the clusters, wherein: A clustering index is set, and data of operating parameters that meet the clustering index compared with the optimal operating parameter value corresponding to the optimal torque are selected into a cluster cluster using a clustering method; Obtaining the boundary values ​​of operating parameters based on the data boundaries of the clusters; An upper limit torque and / or a lower limit torque is determined based on the operating parameter limit values.

9. The method according to claim 8, characterized in that A lower torque below the optimal torque corresponding to the operating parameter boundary value is recorded as the lower boundary torque.

10. The method according to claim 8, characterized in that If a corresponding upper torque higher than the optimal torque can be found at the operating parameter boundary value, the corresponding upper torque is recorded as the upper boundary torque; otherwise, the maximum torque that the engine can provide is used as the upper boundary torque.

11. The method according to any one of claims 2 to 10, characterized in that The operating parameter is the effective fuel consumption rate or the air-fuel ratio.

12. A predictive torque management device, characterized in that: The predictive torque management device comprises a predictive torque management module, which is capable of implementing the method according to any one of claims 1 to 11.

13. A vehicle, characterized in that The vehicle is equipped with the predictive torque management device according to claim 12.

14. A computer-readable medium having a computer program stored thereon, characterized in that When the computer program is executed by a processor, the method according to any one of claims 1 to 11 is implemented.

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