Selection method and selection system of engine braking structure

Abstract

The invention provides a selection method and a selection system for an engine braking structure. The selection method comprises the following steps: acquiring big data statistical information of a target vehicle; according to the big data statistical information, the upper limit vehicle speed of the target vehicle when the target vehicle goes downhill at each downhill gradient is determined; calculating the target braking power required for the target vehicle to reach the balance of each vehicle speed under the full-gradient and full-vehicle-speed driving; according to the power transmission parameters of the target vehicle, the engine rotating speed and the driving gear corresponding to the target braking power are determined; according to the target braking power, the engine rotating speed, the driving gear and the upper limit vehicle speed, the final rotating speed and the final braking power needed by engine braking are selected; and determining the braking structure of the engine based on the final rotating speed and the final braking power. In combination with user actual driving condition data statistics, engine braking performance is determined according to actual condition requirements, an engine braking structure is selected according to the engine braking performance, and then it is guaranteed that the engine braking structure better conforms to the actual driving condition.

Description

Technical Field

[0001] The present invention relates to the technical field of engine braking, and in particular to a method and system for selecting an engine braking structure. Background Art

[0002] As a supplement to the basic wheel brakes of heavy-duty vehicles, auxiliary braking greatly improves the safety of slope driving and effectively reduces the wear of wheel brakes. Auxiliary braking includes: retarder braking, engine braking and motor braking.

[0003] Different engine braking structures achieve different braking powers. In the early stage of engine development, it is necessary to select the engine braking structure based on the actual needs of the user to achieve the desired braking effect.

[0004] At present, in the early stage of engine development, the braking structure of the engine has not fully taken into account the actual needs of users, which leads to unsatisfactory braking effect of the engine. Summary of the invention

[0005] The main purpose of the present invention is to provide a method and system for selecting an engine brake structure, so as to solve the technical problem that the selection of the engine brake structure does not fully combine the actual needs of users.

[0006] In order to achieve the above-mentioned purpose, according to one aspect of the present invention, a method for selecting an engine brake structure is provided, comprising: obtaining big data statistical information of a target vehicle, wherein the big data statistical information at least includes: driving speed, downhill slope and mileage; determining the upper limit speed of the target vehicle when going downhill at each downhill slope according to the big data statistical information; calculating the target braking power required for the target vehicle to achieve a balance at each speed when traveling at all slopes and all speeds; determining the engine speed and driving gear corresponding to the target braking power according to the power transmission parameters of the target vehicle, wherein the power transmission parameters include: transmission ratio, wheel radius and transmission ratio of the main reducer; selecting the final speed and final braking power required for engine braking according to the target braking power, engine speed, driving gear and upper limit speed; and determining the engine braking structure based on the final speed and final braking power.

[0007] Furthermore, based on the big data statistical information, the upper limit speed of the target vehicle when going downhill at each downhill slope is determined, including: constructing a data statistical table of slope-speed-mileage distribution based on the big data statistical information, the data statistical table is used to characterize the mileage proportion of the target vehicle traveling at any speed on each downhill slope; based on the data statistical table and the preset proportion, the upper limit speed is determined.

[0008] Furthermore, based on the data statistics table and the preset proportion, the upper limit speed is determined, including: at a first downhill slope, summing the first driving speed and the mileage proportion corresponding to a speed lower than the first driving speed to obtain a first mileage proportion; at the first downhill slope, summing the mileage proportions corresponding to each driving speed to obtain a first total mileage proportion at the slope; taking the first mileage proportion and the first total mileage proportion as the quotient to obtain a first proportion; when the first proportion is equal to the preset proportion, confirming the first driving speed as the upper limit speed.

[0009] Furthermore, the target braking power required for the target vehicle to achieve a balance at each vehicle speed when traveling at all slopes and all vehicle speeds is calculated, including: obtaining the total mass, driving resistance power, driving speed, full slope range and full vehicle speed range of the target vehicle; and calculating the target braking power based on the total mass, driving resistance power, driving speed, full slope range and full vehicle speed range.

[0010] Furthermore, before determining the engine speed and driving gear corresponding to the target braking power, it is necessary to construct a first comparison table of vehicle speed-slope-target braking power. The first comparison table is used to characterize the first braking power required for the target vehicle to travel at any average speed on each downhill slope, wherein the first braking power is the target braking power.

[0011] Furthermore, according to the power transmission parameters of the target vehicle, the engine speed and driving gear corresponding to the target braking power are determined, including: according to the power transmission parameters of the target vehicle, calculating the driving speed corresponding to each engine speed in each transmission gear, and constructing a second speed-gear-vehicle speed comparison table; according to the second comparison table and the first comparison table, a plurality of third comparison tables are obtained, and the plurality of third comparison tables are used to characterize the second braking power required for the engine to run at any speed and any gear at each downhill slope, wherein the second braking power is the target braking power.

[0012] Furthermore, according to the target braking power, engine speed, driving gear and upper limit vehicle speed, the final speed and final braking power required for engine braking are selected, including: combining the second comparison table and the first comparison table, selecting multiple driving gears matching the upper limit vehicle speed from the third comparison table; determining the final gear from the selected multiple driving gears in combination with the downhill slope corresponding to the upper limit vehicle speed; determining the target speed corresponding to the target braking power according to the final gear; drawing the speed-braking power scatter points according to the target speed and the target braking power, selecting the outermost scatter points for envelope connection, and generating a speed-braking power curve; determining the final speed and final braking power based on the speed-braking power curve.

[0013] Furthermore, in combination with the downhill slope corresponding to the upper limit vehicle speed, the final gear is determined from the selected multiple driving gears, including: when the downhill slope corresponding to the upper limit vehicle speed is greater than or equal to the preset slope, a lower gear among the multiple driving gears is selected as the final gear.

[0014] Furthermore, in combination with the downhill slope corresponding to the upper limit vehicle speed, the final gear is determined from the selected multiple driving gears, including: when the downhill slope corresponding to the upper limit vehicle speed is less than the preset slope, a higher gear among the selected multiple driving gears is selected as the final gear.

[0015] According to another aspect of the present invention, a system for selecting an engine brake structure is provided, comprising: an acquisition module, the acquisition module is used to acquire big data statistical information of a target vehicle, wherein the big data statistical information at least includes: driving speed, downhill slope and mileage; a first calculation module, the first calculation module is used to determine the upper limit speed of the target vehicle when going downhill at each downhill slope according to the big data statistical information; a second calculation module, the second calculation module is used to calculate the target braking power required for the target vehicle to achieve a balance of various vehicle speeds when traveling at all slopes and all vehicle speeds; a third calculation module, the third calculation module is used to determine the engine speed and driving gear corresponding to the target braking power according to the power transmission parameters of the target vehicle, wherein the power transmission parameters include: transmission ratio, wheel radius and transmission ratio of the main reducer; a first selection module, the first selection module is used to select the final speed and final braking power required for engine braking according to the target braking power, engine speed, driving gear and upper limit speed; a second selection module, the second selection module is used to determine the braking structure of the engine based on the final speed and final braking power.

[0016] By applying the technical solution of the present invention, the upper limit vehicle speed at each downhill slope is determined based on the big data statistical information of the target vehicle, and the final speed and final braking power required for engine braking are determined in combination with the upper limit vehicle speed, the target braking power required by the target vehicle when going downhill, and the power transmission parameters of the target vehicle, and then the engine braking structure is determined based on the final speed and final braking power. The above solution combines the actual driving condition data statistics of the user, determines the engine braking performance according to the actual working condition requirements, selects the corresponding engine braking structure according to the engine braking performance, and thus ensures that the established engine braking structure is more in line with the actual driving condition. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0018] Figure 1A schematic flow chart showing a method for selecting an engine brake structure in the present invention is shown;

[0019] Figure 2 A schematic diagram of the curve of the engine speed-brake power in the present invention is shown. DETAILED DESCRIPTION

[0020] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0021] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0022] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein, for example. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0023] Now, exemplary embodiments according to the present application will be described in more detail with reference to the accompanying drawings. However, these exemplary embodiments may be implemented in a variety of different forms and should not be construed as being limited to the embodiments described herein. It should be understood that these embodiments are provided to make the disclosure of the present application thorough and complete, and to fully convey the concepts of these exemplary embodiments to those of ordinary skill in the art. In the accompanying drawings, for the sake of clarity, the thickness of the layers and regions may be enlarged, and the same reference numerals are used to represent the same devices, and thus their descriptions will be omitted.

[0024] Combination Figure 1 As shown, according to a specific embodiment of the present application, a method for selecting an engine brake structure is provided.

[0025] Specifically, the method for selecting the engine brake structure includes the following steps:

[0026] Step S1: Obtain big data statistical information of the target vehicle, wherein the big data statistical information at least includes: driving speed, downhill slope and mileage.

[0027] Step S2: Determine the upper speed limit of the target vehicle when going downhill at each downhill slope based on the big data statistical information.

[0028] Step S3: Calculate the target braking power required for the target vehicle to achieve a balance at each vehicle speed when the target vehicle is traveling at all slopes and all vehicle speeds.

[0029] Step S4: determining the engine speed and driving gear corresponding to the target braking power according to the power transmission parameters of the target vehicle, wherein the power transmission parameters include: transmission ratio, wheel radius and transmission ratio of the final reducer.

[0030] Step S5: According to the target braking power, the engine speed, the driving gear and the upper speed limit, the final speed and the final braking power required for the engine braking are selected.

[0031] Step S6: Determine the braking structure of the engine based on the final rotation speed and the final braking power.

[0032] In the embodiment of the present application, the upper limit vehicle speed at each downhill slope is determined based on the big data statistical information of the target vehicle, and the final speed and final braking power required for engine braking are determined in combination with the upper limit vehicle speed, the target braking power required by the target vehicle when going downhill, and the power transmission parameters of the target vehicle, and then the engine braking structure is determined based on the final speed and final braking power. The above scheme combines the actual driving condition data statistics of the user, determines the engine braking performance according to the actual working condition requirements, selects the corresponding engine braking structure according to the engine braking performance, and thus ensures that the established engine braking structure is more in line with the actual driving condition.

[0033] It should be noted that the preset vehicle matched with the engine to be developed has the same vehicle operating conditions as the target vehicle, wherein the vehicle operating conditions at least include: the total mass of the vehicle and the driving area of ​​the vehicle.

[0034] In an exemplary embodiment of the present application, determining the upper limit speed of the target vehicle when going downhill at each downhill slope according to the big data statistical information in step S2 includes the following steps:

[0035] Step S21: construct a data statistical table of slope-speed-mileage distribution based on the big data statistical information, and the data statistical table is used to characterize the mileage ratio of the target vehicle at any driving speed on each downhill slope.

[0036] Step S22: Determine the upper speed limit based on the data statistics table and the preset ratio, wherein the preset ratio can be calibrated according to actual needs.

[0037] Through the above steps S21 to S22, the big data statistical information is integrated into a data statistical table, and the mileage is divided according to the road slope and the vehicle speed. The mileage proportion of the target vehicle traveling at each speed in each downhill slope section can be quickly obtained, and then the upper limit speed can be determined in combination with the preset proportion.

[0038] For example, the data statistics table of the slope-vehicle speed-mileage distribution in step S21 is as shown in the following table:

[0039] Statistics table

[0040]

[0041] In step S22, the specific calculation process for determining the upper speed limit based on the data statistics table and the preset ratio is as follows:

[0042] Step S221: At a first downhill slope, the first driving speed and the mileage percentage corresponding to a speed lower than the first driving speed are summed to obtain a first mileage percentage.

[0043] Exemplarily, the first downhill slope is -6 to -7%, the first driving speed is 75 to 80 km / h, and the first mileage proportion C1 is calculated according to the above data statistics table, C1=0.02+0.02+...+0.01+0.01+0.01.

[0044] Step S222: At the first downhill slope, the mileage percentages corresponding to the vehicle speeds are summed to obtain a first total mileage percentage at the slope.

[0045] Exemplarily, the first downhill slope is -6 to -7%. The first total mileage proportion C2 is calculated according to the above data statistics table, C2=0.01+0.01+0.01+0.02+0.02+…+0.01+0.01+0.01.

[0046] Step S223: Taking the quotient of the first mileage proportion and the first total mileage proportion, a first proportion is obtained.

[0047] Exemplarily, the first proportion C0=C1 / C2.

[0048] Step S224: when the first proportion is equal to the preset proportion, confirming the first driving speed as the upper limit speed.

[0049] Exemplarily, the preset proportion is 90%. If C0=90%, 75-80 km / h is determined as the upper limit speed for driving under -6--7%; if C0≠90%, C1 is adjusted according to the above data statistics table.

[0050] In an exemplary embodiment of the present application, the target braking power required for the target vehicle to achieve a balance at each vehicle speed when the target vehicle is traveling at full slope and full speed in step S3 includes the following calculation steps:

[0051] Step S31: Obtain the total mass, driving resistance power, driving speed, full slope range and full speed range of the target vehicle.

[0052] Step S32: Calculate the target braking power according to the total mass, the driving resistance power, the driving speed, the full slope range and the full speed range.

[0053] Specifically, the target braking power is P 0 , the total mass of the target vehicle is M, and the driving resistance power of the target vehicle is P 1， The road slope angle is θ, the acceleration of gravity is g, and the speed of the target vehicle is u a , where P 0 =Mg sinθ×u a -P 1 .

[0054] In an exemplary embodiment of the present application, before determining the engine speed and driving gear corresponding to the target braking power, it is necessary to construct a first comparison table of vehicle speed-slope-target braking power, wherein the first comparison table is used to characterize the first braking power required for the target vehicle to travel at any average speed on each downhill slope, wherein the first braking power is the target braking power.

[0055] Specifically, the first comparison table is based on P 0 =Mg sinθ×u a -P 1 The first comparison table is as follows:

[0056] First comparison table

[0057]

[0058] Furthermore, in step S4, the engine speed and driving gear corresponding to the target braking power are determined according to the power transmission parameters of the target vehicle, including the following calculation steps:

[0059] Step S41: Calculate the vehicle speed corresponding to each engine speed at each transmission gear according to the power transmission parameters of the target vehicle, and construct a second speed-gear-vehicle speed comparison table.

[0060] Exemplarily, the power transmission parameters of the target vehicle include: engine speed n, transmission ratio i g , Main reducer transmission ratio i 0 And the wheel radius r, the corresponding driving speed of the engine speed in each transmission gear is u a , according to Construct a second comparison table, wherein the second comparison table is as follows:

[0061] Second comparison table

[0062]

[0063]

[0064] Step S42: Based on the second comparison table and the first comparison table, multiple third comparison tables are obtained, and the multiple third comparison tables are used to characterize the second braking power required for the engine to run at any speed and any gear at each downhill slope, wherein the second braking power is the target braking power.

[0065] Exemplarily, the second comparison table is integrated with the first comparison table to obtain a plurality of third comparison tables, and a third comparison table of speed-gear-power is constructed taking a slope of -6% as an example, wherein the third comparison table (slope of -6%) is as follows:

[0066] The third comparison table (slope is -6%)

[0067]

[0068] In an exemplary embodiment of the present application, in step S5, the final speed and final braking power required for engine braking are selected according to the target braking power, the engine speed, the driving gear and the upper speed limit, including:

[0069] Step S51: combining the second comparison table and the first comparison table, selecting a plurality of driving gears matching the upper limit vehicle speed from the third comparison table.

[0070] For example, taking the road slope of -6% as an example, when the road slope is -6%, the upper limit speed is 75km / h; according to the second comparison table, the speed corresponding to 75km / h is 2100rpm, and the corresponding driving gear is 8th gear; according to the third comparison table, when the engine runs at 2100rpm in 8th gear, the target speed of the engine is 158.4kw.

[0071] Step S52: Determine the final gear position from the selected multiple driving gear positions in combination with the downhill slope corresponding to the upper speed limit.

[0072] For example, when traveling on a road slope of -6%, the vehicle speed ranges from 0 to 75 km / h. According to the second comparison table and the third comparison table, the driving gears involved are 7th and 8th gears, that is, the final gears are 7th and 8th gears.

[0073] Step S53: Determine the target speed corresponding to the target braking power according to the final gear position.

[0074] Step S54: according to the target speed and the target braking power, the speed-braking power scatter points are plotted, and the outermost scatter points are selected for envelope connection to generate a speed-braking power curve.

[0075] For example, according to the third comparison table, the scattered points are all the braking power points involved in the 7th and 8th gears; Figure 2 As shown in the figure, the scattered points of speed-brake power are plotted, and the outermost scattered points are selected to connect the generated envelope. The power point on the envelope is taken as the brake power of the engine.

[0076] Step S55: Determine the final speed and final braking power based on the speed-braking power curve. Figure 2 The power point on the envelope line is taken as the braking power point of the engine, which corresponds to the final speed and final braking power.

[0077] Preferably, the final gear is determined from the selected multiple driving gears in combination with the downhill slope corresponding to the upper limit vehicle speed, including: when the downhill slope corresponding to the upper limit vehicle speed is greater than or equal to the preset slope, a lower gear among the selected multiple driving gears is selected as the final gear.

[0078] Preferably, the final gear is determined from the selected multiple driving gears in combination with the downhill slope corresponding to the upper limit vehicle speed, including: when the downhill slope corresponding to the upper limit vehicle speed is less than the preset slope, a higher gear among the selected multiple driving gears is selected as the final gear.

[0079] According to another specific embodiment of the present application, a system for selecting an engine brake structure is provided.

[0080] Specifically, the engine brake structure selection system includes: an acquisition module, a first calculation module, a second calculation module, a third calculation module, a first selection module and a second selection module. The acquisition module is used to obtain the big data statistical information of the target vehicle, wherein the big data statistical information at least includes: driving speed, downhill slope and mileage. The first calculation module is used to determine the upper limit speed of the target vehicle when it is downhill at each downhill slope according to the big data statistical information. The second calculation module is used to calculate the target braking power required for the target vehicle to achieve the balance of each vehicle speed when the target vehicle is driving at full slope and full speed. The third calculation module is used to determine the engine speed and driving gear corresponding to the target braking power according to the power transmission parameters of the target vehicle, wherein the power transmission parameters include: transmission ratio, wheel radius and transmission ratio of the main reducer. The first selection module is used to select the final speed and final braking power required for engine braking according to the target braking power, engine speed, driving gear and upper limit speed. The second selection module is used to determine the engine braking structure based on the final speed and final braking power.

[0081] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0082] Based on the big data statistics of the target vehicle, the upper limit speed when going downhill at each downhill slope is determined. Combined with the upper limit speed, the target braking power required by the target vehicle when going downhill, and the power transmission parameters of the target vehicle, the final speed and final braking power required for engine braking are determined, and then the engine braking structure is determined based on the final speed and final braking power. The above scheme combines the actual driving condition data statistics of users, determines the engine braking performance according to the actual working condition requirements, and selects the corresponding engine braking structure according to the engine braking performance, thereby ensuring that the established engine braking structure is more in line with the actual driving condition.

[0083] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0084] In addition to the above, it should be noted that "one embodiment", "another embodiment", "embodiment", etc. mentioned in this specification refer to the specific features, structures or characteristics described in conjunction with the embodiment included in at least one embodiment generally described in this application. The same expression appearing in multiple places in the specification does not necessarily refer to the same embodiment. Further, when describing a specific feature, structure or characteristic in conjunction with any embodiment, it is claimed that the realization of such feature, structure or characteristic in conjunction with other embodiments also falls within the scope of the present invention.

[0085] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0086] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for selecting an engine brake structure, characterized in that: include: Obtaining big data statistical information of the target vehicle, wherein the big data statistical information at least includes: driving speed, downhill slope, and mileage; Determining the upper limit vehicle speed of the target vehicle when going downhill at each downhill slope according to the big data statistical information; Calculating the target braking power required for the target vehicle to achieve a balance at each vehicle speed when the target vehicle is traveling at all slopes and all vehicle speeds; Determining the engine speed and driving gear corresponding to the target braking power according to the power transmission parameters of the target vehicle, wherein the power transmission parameters include: transmission ratio, wheel radius and transmission ratio of the final reducer; Selecting a final speed and a final braking power required for engine braking according to the target braking power, the engine speed, the driving gear and the upper speed limit; Based on the final rotational speed and the final braking power, a braking structure of the engine is determined.

2. The selection method according to claim 1, characterized in that: Determining the upper limit speed of the target vehicle when going downhill at each downhill slope according to the big data statistical information includes: According to the big data statistical information, a data statistical table of slope-speed-mileage distribution is constructed, wherein the data statistical table is used to characterize the mileage ratio of the target vehicle at any driving speed on each downhill slope; Based on the data statistics table and the preset ratio, the upper limit vehicle speed is determined.

3. The selection method according to claim 1, characterized in that: Determining the upper speed limit based on the data statistics table and the preset proportion includes: At a first downhill slope, summing a first driving speed and a mileage percentage corresponding to a speed lower than the first driving speed to obtain a first mileage percentage; At the first downhill slope, the mileage proportions corresponding to the vehicle speeds are summed to obtain the first total mileage proportion at the slope; Taking the first mileage proportion and the first total mileage proportion as a quotient to obtain a first proportion; When the first proportion is equal to the preset proportion, the first driving speed is confirmed as the upper limit speed.

4. The selection method according to claim 1, characterized in that: Calculating the target braking power required for the target vehicle to achieve a balance at each vehicle speed when the target vehicle is traveling at all slopes and all vehicle speeds, including: Obtaining the total mass, driving resistance power, driving speed, full slope range and full speed range of the target vehicle; The target braking power is calculated according to the total mass, the driving resistance power, the driving speed, the full slope range and the full vehicle speed range.

5. The selection method according to claim 4, characterized in that: Before determining the engine speed and driving gear corresponding to the target braking power, it is necessary to construct a first comparison table of vehicle speed-slope-target braking power, wherein the first comparison table is used to characterize the first braking power required for the target vehicle to travel at any average speed on each downhill slope, wherein the first braking power is the target braking power.

6. The selection method according to claim 5, characterized in that: Determining an engine speed and a driving gear corresponding to the target braking power according to a power transmission parameter of the target vehicle includes: According to the power transmission parameters of the target vehicle, the corresponding driving speed of each engine speed in each transmission gear is calculated, and a second comparison table of speed-gear-vehicle speed is constructed; Based on the second comparison table and the first comparison table, multiple third comparison tables are obtained, and the multiple third comparison tables are used to characterize the second braking power required for the engine to run at any speed and any gear at each downhill slope, wherein the second braking power is the target braking power.

7. The selection method according to claim 6, characterized in that: According to the target braking power, the engine speed, the driving gear and the upper speed limit, a final speed and a final braking power required for engine braking are selected, including: In combination with the second comparison table and the first comparison table, a plurality of driving gears matching the upper speed limit are selected from the third comparison table; Determining a final gear position from the selected multiple driving gear positions in combination with the downhill slope corresponding to the upper speed limit; Determining a target speed corresponding to the target braking power according to the final gear position; According to the target speed and the target braking power, the speed-braking power scatter points are plotted, and the outermost scatter points are selected for envelope connection to generate a speed-braking power curve; The final speed and the final braking power are determined based on the speed-braking power curve.

8. The selection method according to claim 7, characterized in that: Determining the final gear position from the selected multiple driving gear positions in combination with the downhill slope corresponding to the upper speed limit includes: When the downhill slope corresponding to the upper limit vehicle speed is greater than or equal to the preset slope, a lower gear among the multiple driving gears is selected as the final gear.

9. The selection method according to claim 7, characterized in that: Determining the final gear position from the selected multiple driving gear positions in combination with the downhill slope corresponding to the upper speed limit includes: When the downhill slope corresponding to the upper speed limit is less than the preset slope, a higher gear among the multiple driving gears is selected as the final gear.

10. A system for selecting an engine brake structure, characterized in that: include: An acquisition module, the acquisition module is used to acquire big data statistical information of the target vehicle, wherein the big data statistical information at least includes: driving speed, downhill slope and mileage; A first calculation module, the first calculation module is used to determine the upper limit speed of the target vehicle when going downhill at each downhill slope according to the big data statistical information; A second calculation module, the second calculation module is used to calculate the target braking power required for the target vehicle to achieve a balance at each vehicle speed when the target vehicle is traveling at full slope and full speed; a third calculation module, the third calculation module being used to determine the engine speed and the driving gear corresponding to the target braking power according to the power transmission parameters of the target vehicle, wherein the power transmission parameters include: a transmission ratio, a wheel radius, and a transmission ratio of a final reducer; A first selection module, the first selection module is used to select the final speed and final braking power required for engine braking according to the target braking power, the engine speed, the driving gear and the upper limit vehicle speed; A second selection module is used to determine the braking structure of the engine based on the final rotational speed and the final braking power.

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