A method for setting the maximum front and rear axle loads of a passenger car

Abstract

The present invention provides a method for setting the maximum front and rear axle loads of a passenger car, which includes the following steps: obtaining specific key design parameters; calculating and obtaining the no-load front and rear axle loads in the no-load state, where the no-load state includes the basic curb weight state and the maximum curb weight state; obtaining the loading point position coordinates and establishing a loading model; based on the loading model, curb weight, no-load front and rear axle loads, and maximum design gross mass, respectively, taking the basic curb weight and the maximum curb weight as benchmarks, performing loading according to a preset loading method and calculating the front and rear axle loads accordingly to form an axle load matrix; analyzing the obtained axle load matrix, screening to obtain the maximum values of the front axle load and the rear axle load, and obtaining the maximum front axle load and the maximum rear axle load after correction. By establishing a loading model and designing a special loading method, the present invention can comprehensively evaluate the axle loads in various states and accurately achieve the maximum axle load design.

Description

Technical Field

[0001] The present invention relates to the field of automobiles, and specifically, to a method for setting the maximum front and rear axle loads of a passenger car. Background Art

[0002] During the development process of new automobile products, axle load calculation is an extremely important task. Axle load distribution is an important factor affecting aspects such as the power performance, handling stability, comfort, safety, and tire life of an automobile. During the automobile design process, the specific vertical loads of each axle of the whole vehicle on the ground directly affect the selection of components, the tires, and the load-bearing capacity of the front and rear axles. Only by accurately calculating the axle loads of the whole vehicle and then reasonably matching and optimizing according to the performance requirements such as the handling stability and braking of the whole vehicle can the various performances of the newly developed product be ensured to reach the optimum.

[0003] For the axle load calculation of passenger cars, the currently widely used method is to simplify the vehicle into a support beam using the static equilibrium method, calculate the axle loads of the vehicle in the unloaded state and various loading states respectively, and comprehensively consider the front and rear axle loads of the whole vehicle in each state to find the maximum values of the front and rear axles for guiding the development of automobile design. However, the current design method for the maximum axle load of passenger cars is still insufficient, the working condition coverage dimension is single, and it is difficult to accurately guide the general layout and chassis design. Summary of the Invention

[0004] Aiming at the defects in the prior art, the purpose of the present invention is to provide a method for setting the maximum front and rear axle loads of a passenger car, aiming to comprehensively evaluate the axle loads in each state by establishing a loading model and through special loading methods and correction methods, and to accurately achieve the maximum axle load design through analysis and correction.

[0005] To achieve the above invention purpose, the present invention adopts the following technical solutions:

[0006] Provide a method for setting the maximum front and rear axle loads of a passenger car, including the following steps:

[0007] In step S1, obtain specific key design parameters; the specific key design parameters include curb weight, center of mass position, maximum design gross mass, wheelbase, track width, wheel center coordinates; the curb weight includes basic curb weight and maximum curb weight;

[0008] In step S2, in the unloaded state, calculate and obtain the unloaded front and rear axle loads; the unloaded state includes the basic curb weight state and the maximum curb weight state;

[0009] In step S3, obtain the loading point position coordinates and establish a loading model; the loading point position coordinates include seat loading point coordinates and trunk loading point coordinates;

[0010] In step S4, based on the loaded model, curb weight, front and rear axle loads without load, and maximum designed total mass, with the basic curb weight and maximum curb weight as benchmarks respectively, loading is carried out according to a preset loading method and the front and rear axle loads are calculated accordingly to form an axle load matrix;

[0011] In step S5, the obtained axle load matrix is analyzed to screen out the maximum values of the front axle load and rear axle load, and the maximum front axle load and maximum rear axle load are obtained according to a preset correction method;

[0012] The preset loading method includes a loading method of loading to the minimum designed total mass and a loading method of loading to the maximum designed total mass;

[0013] The loading method of loading to the minimum designed total mass includes: Loading method 1: Each seat is loaded with the mass of a single passenger respectively, and the mass loaded in the trunk is the product of the standard luggage mass and the number of passengers; Loading method 2: Each seat is loaded with the sum of the mass of a single passenger and the standard luggage mass respectively, and the mass loaded in the trunk is zero;

[0014] The loading method of loading to the maximum designed total mass includes: Loading method 3: Each seat is loaded with the mass of a single passenger respectively, and goods are loaded into the trunk until the maximum designed total mass is reached; Loading method 4: Each seat in the first row and each seat in the second row are loaded with the mass of a single passenger respectively, the third row seats are folded, and goods are loaded on the rear floor of the second row until the maximum designed total mass is reached; Loading method 5: Each seat in the first row and each seat in the second row are loaded with the sum of the mass of a single passenger and the standard luggage mass respectively, the third row seats are folded, and goods are loaded on the rear floor of the second row until the maximum designed total mass is reached;

[0015] The preset correction method is: determining an axle load correction coefficient according to the estimation deviation of the vehicle center of mass position, and obtaining the maximum front axle load and maximum rear axle load according to the axle load correction coefficient.

[0016] Preferably, in step S2, the basic curb weight includes: the mass of the basic power transmission system, the mass of all standard fittings and accessories installed at the general assembly plant, the mass of the cargo box, the calculated mass of the liquid in the passenger car, the mass when the fuel in the fuel tank reaches a preset ratio; the maximum curb weight is the sum of the basic curb weight and the maximum optional parts mass.

[0017] Preferably, in step S3, the measurement of the vehicle digital model is used to obtain the coordinates of the measured wheel center, the measured seat H-point, and the measured trunk loading point. When establishing the loading model, the coordinate points are symmetrically processed and the coordinate of the weight loading point is obtained according to the national standard of the automotive H-point determination procedure; the loading point positions include the left of the first row seat, the right of the first row seat, the left of the second row seat, the middle of the second row seat, the right of the second row seat, the left of the third row seat, the right of the third row seat, the 7-seat loading point of the trunk, and the 5-seat loading point of the trunk.

[0018] In step S4, the mass of a single passenger and the mass of standard luggage are set according to the requirements of the national standard.

[0019] Preferably, the following steps are further included:

[0020] In step S6, the vehicle models are classified according to the powertrain adopted by the vehicle models, and the same set of maximum front axle load and maximum rear axle load are set for the same type of vehicle models.

[0021] Preferably, in step S2, according to the principle of lever balance, the no-load front and rear axle loads are calculated according to the following formula:

[0022] M 后轴 = M*X / L;

[0023] M 前轴 = M - M 后轴 ;

[0024] Wherein, M 后轴 is the rear axle load, M 前轴 is the front axle load, X is the distance from the vehicle center of mass to the front axle; L is the vehicle wheelbase; M is the curb weight.

[0025] Preferably, in step S4, a calculation system is established. After the user inputs the vehicle parameters through the calculation system interface and visually sets the loading method, the calculation system calculates and outputs the axle load data and wheel load data.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The method provided by the present invention aims at passenger cars. By establishing a loading model, designing a special loading method, and combining the maximum design gross mass and the minimum design gross mass, the front and rear axle loads under different loading conditions such as no-load, half-load, and full-load are analyzed under the basic curb weight and the maximum curb weight benchmark, and the axle load values are corrected. The working conditions are comprehensively covered to ensure design redundancy, avoid the sharp increase in engineering change costs caused by over-limit loads in the later stage, take into account the subsequent model change requirements of automotive design, and reserve bearing capacity for the model change project. Description of the Drawings

[0028] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non - limiting embodiments read in conjunction with the accompanying drawings:

[0029] Figure 1 It is a schematic flowchart of the method described in the embodiment;

[0030] Figure 2 It is a schematic diagram of the loading point positions in the 7 - seat state in the embodiment;

[0031] Figure 3 It is a schematic diagram of the loading point positions in the 5 - seat state in the embodiment. Detailed implementation manners

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. Usually, the components of the embodiments of the present application described and illustrated in the accompanying drawings herein can be arranged and designed in various different configurations.

[0033] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application claimed, but merely represents selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts fall within the scope of protection of the present application.

[0034] It should be noted that: Similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. In addition, all directional indications (such as up, down, left, right, front, back, bottom...) in the present application are only used to explain the relative positional relationship and movement conditions between components in a specific posture (as shown in the drawings). If the specific posture changes, the directional indications will also change accordingly.

[0035] Embodiment

[0036] This embodiment provides a method for setting the maximum front and rear axle loads of a passenger car, aiming to comprehensively evaluate the axle loads in various states by establishing a loading model and designing through a special loading method, and accurately achieve the maximum axle load design through analysis and correction to meet the selection of suspensions, axles, and tires that can meet the bearing requirements. Specifically, as Figure 1 shown, the method provided in this embodiment specifically includes the following steps:

[0037] In step S1, specific key design parameters are obtained. Before calculating the axle load of a vehicle, it is necessary to know specific key design parameters, including curb weight, center of mass position, maximum design gross mass, wheelbase, track width, and wheel center coordinates, to ensure the accuracy of vehicle axle load calculation. The curb weight should include the basic curb weight and the maximum curb weight. The basic curb weight is generally consistent with the information defined in the product manual, including: the mass of the basic power transmission system, the mass of all standard parts and accessories installed at the general assembly plant, the mass of the cargo box, the calculated mass of all liquids in the passenger car, including the calculated mass of all engine oil, lubricating fluid, coolant, and other liquids, and the mass when the fuel in the fuel tank reaches a preset ratio (for example, the fuel reaches 90% of the maximum fuel tank capacity); the maximum curb weight is the sum of the basic curb weight and the maximum optional parts mass, and the maximum optional parts mass includes the heaviest power system, vehicle type and driving configuration, and product deviation. For a two-axle vehicle, assuming the basic vehicle type is a rigid body, it can be simplified as a support beam for calculation. The specific key design parameters obtained in this example are shown in Table 1.

[0038] Table 1:

[0039]

[0040] In step S2, the axle load is calculated under the no-load state to obtain the front and rear axle loads under no-load. The no-load state is divided into two states: the basic curb weight and the maximum curb weight. Further, according to the lever balance principle, the front and rear axle loads under no-load can be calculated according to Formula 1. Formula 1 is:

[0041] M 后轴 = M*X / L;

[0042] M 前轴 = M-M 后轴 ;

[0043] In Formula 1, M 后轴 is the rear axle load, M 前轴 is the front axle load, X is the distance from the vehicle's center of mass to the front axle; L is the vehicle's wheelbase; M is the curb weight. The front and rear axle loads under no-load include the front and rear axle loads corresponding to the basic curb weight and the maximum curb weight calculated respectively according to Formula 1. In this embodiment, the basic curb weight is 2188 KG, the maximum curb weight is 2277 KG, the wheelbase is 2850 mm, and the distance from the center of mass to the front axle is 1456 mm. The front and rear axle loads calculated according to Formula 1 are shown in Table 2.

[0044] Table 2:

[0045]

[0046] In step S3, the coordinates of the loading point positions are obtained to establish a loading model. For the loading point positions applied in the loading model, the measured wheel center coordinates, the measured seat H-point, and the measured trunk loading points are first obtained in the vehicle digital model. When establishing the loading model, the above-mentioned measured coordinate points are symmetrically processed and fine-tuned, and the weight loading point coordinates are obtained according to the national standard for the automotive H-point determination procedure (in this embodiment, according to the provisions of "GB / T 11563-1995 Automotive H-point determination procedure"), including the X-direction centroid coordinates of the seat and the X-direction coordinates of the trunk loading point. The X-direction centroid coordinates of the seat include the left of the first row seat (R1-L), the right of the first row seat (R1-R), the left of the second row seat (R2-L), the middle of the second row seat (R2-M), the right of the second row seat (R2-R), the left of the third row seat (R3-L), and the right of the third row seat (R3-R). The X-direction coordinates of the trunk loading point include the 5-seat loading point of the trunk (L-5S) and the 7-seat loading point of the trunk (L-7S). Exemplarily, the measured weight loading point coordinates are shown in Table 3.

[0047] Table 3:

[0048]

[0049] In step S4, based on the loading model, the curb weight, the front and rear axle loads, and the maximum design gross mass, loading is carried out respectively with the basic curb weight and the maximum curb weight as the benchmarks according to the preset loading method, and the front and rear axle loads are calculated accordingly to form an axle load matrix.

[0050] The preset loading method sets the single passenger mass and the standard luggage mass according to the national standard requirements. In this embodiment, the single passenger mass is set to 68 KG and the standard luggage mass is set to 7 KG. The preset loading method ensures that the gross vehicle mass (GVM) is greater than or equal to the sum of the curb weight, the full-load passenger mass, and the standard luggage mass corresponding to the full-load passenger mass, and less than or equal to the maximum design gross mass, and should include the loading methods for loading to the minimum design gross mass and loading to the maximum design gross mass. Simulating the loading according to the maximum design gross mass and the minimum design gross mass can cover extreme working conditions, ensure design redundancy, improve the calculation accuracy of the axle load in the initial stage of design, and avoid a sharp increase in the engineering change cost caused by over-limit load in the later stage.

[0051] The distribution of each loading position is as Figure 2 、 Figure 3 shown, where the steering wheel 1, the instrument panel 2, and the center console 3 are not loaded with passengers or luggage. The seat loading points include: the left of the first row seat 2, the right of the first row seat 3, the left of the second row seat 4, the middle of the second row seat 5, the right of the second row seat 6, the left of the third row seat 7, and the right of the third row seat 8. The trunk loading points include: the 7-seat loading point of the trunk 9 and the 5-seat loading point of the trunk 12. The loading method for loading to the minimum design gross mass includes:

[0052] Loading method 1: Each seat is separately loaded with the mass of a single passenger (68 kg / person), and the mass loaded in the trunk is the product of the standard luggage mass and the number of passengers (49 kg). The axle load calculation results for this loading method (axle load unit: kg) are shown in Table 4;

[0053] Table 4:

[0054]

[0055] Loading method 2: Each seat is separately loaded with the sum of the mass of a single passenger (68 kg / person) and the standard luggage mass (7 kg), and the mass loaded in the trunk is zero. The axle load calculation results for this loading method are shown in Table 5 (axle load unit: kg).

[0056] Table 5:

[0057]

[0058] The loading methods for loading to the maximum design gross mass include:

[0059] Loading method 3: Each seat is separately loaded with the mass of a single passenger (68 kg / person), and goods are loaded into the trunk until the maximum design gross mass is reached. The mass of the goods loaded in the trunk in this embodiment of this loading method is 236 kg. The axle load calculation results for this loading method are shown in Table 6 (axle load unit: kg);

[0060] Table 6:

[0061]

[0062] Loading method 4: Each seat in the first row and each seat in the second row are separately loaded with the mass of a single passenger (68 kg / person). The third row seats are folded, and goods are loaded on the rear floor of the second row until the maximum design gross mass is reached. The mass of the goods loaded in the trunk in this embodiment of this loading method is 372 kg. The axle load calculation results are shown in Table 7 (axle load unit: kg);

[0063] Table 7:

[0064]

[0065] Loading method 5: Each seat in the first row and each seat in the second row are separately loaded with the sum of the mass of a single passenger (68 kg / person) and the standard luggage mass (7 kg). The third row seats are folded, and goods are loaded on the rear floor of the second row until the maximum design gross mass is reached. The mass of the goods loaded in the trunk in this embodiment of this loading method is 337 kg. The axle load calculation results are shown in Table 8 (axle load unit: kg).

[0066] Table 8:

[0067]

[0068] Combining the axle load calculation results under various loading methods, the axle load matrix is obtained as shown in Table 9.

[0069] Table 9:

[0070]

[0071] Furthermore, in this embodiment, a calculation system is established. After the user inputs vehicle parameters through the calculation system interface and visually sets the loading method, the calculation system calculates and outputs axle load data and wheel load data according to the vehicle parameters and loading method input by the user. Specifically, the calculation system allows the user to input vehicle parameters including the coordinates of the wheel centers of each wheel, the coordinates of each seat, the trunk coordinates, the wheelbase, and the track width. At the same time, the calculation system can visually set the loading method according to the user, customize the loading weight of the seat, the loading weight of the trunk, the fuel tank weight, and the battery weight. The calculation system generates a vehicle loading simulation diagram based on the loading method set by the user, simulates the customer's vehicle use scenario, and calculates and obtains the axle load data and wheel load data according to the pre-designed calculation method based on the data input by the user.

[0072] In step S5, the axle load matrix obtained in step S4 is analyzed to screen out the maximum values of the front axle load and the rear axle load, and the maximum front axle load and the maximum rear axle load are obtained according to the preset correction method. The preset correction method is to determine the axle load correction coefficient according to the estimated deviation of the vehicle center of mass position, and obtain the maximum front axle load and the maximum rear axle load according to the axle load correction coefficient. In this embodiment, the maximum value of the front axle load obtained by screening is 1207 KG, and the maximum value of the rear axle load is 1792 KG. To prevent future weight gain of the curb weight and consider retaining sufficient design redundancy, the maximum values of the front axle load and the rear axle load are corrected according to the axle load correction coefficient of 1.01. Finally, the maximum front axle is 1220 KG, and the maximum rear axle is 1810 KG, which can be used to guide the design and development of the whole vehicle; if the measured deviation of the vehicle center of mass position exceeds the deviation threshold after the vehicle is off the production line, the axle load correction coefficient is amplified, and the maximum front axle load and the maximum rear axle load are obtained based on the amplified axle load correction coefficient. The method provided in this embodiment can enhance the safety of the designed vehicle by correcting the axle load value, and avoid the risk of suspension overload or tire blowout caused by excessive deviation of the center of mass.

[0073] In step S6, the vehicle models are classified according to the powertrain adopted by the vehicle models, and the same set of maximum front axle load and maximum rear axle load are set for the same type of vehicle models. In the scenario of developing multiple vehicle models simultaneously in a project, such as diesel / gasoline vehicle models, long / short axle vehicle models, AT / MT vehicle models, etc., the axle loads of vehicle models under the same powertrain are classified into one category. For different vehicle models under the same powertrain, only one set of unified maximum front axle load and maximum rear axle load standards needs to be set, without the need to design axle load parameters for each vehicle model separately, reducing repeated calculations and design iterations.

[0074] The method provided in this embodiment is for passenger vehicles. By establishing a loading model and designing a special loading method, the front and rear axle loads under different loading conditions such as no-load, half-load, and full-load are analyzed based on the basic curb weight and the maximum curb weight benchmark, and the final maximum front and rear axle loads are determined. These axle loads are input into the general layout, chassis, and axle systems for reference in design and selection. It can achieve that the same set of chassis systems can carry multiple vehicle models, while also taking into account the subsequent model change requirements in automotive design, and reserving bearing capacity for the model change project.

[0075] The specific embodiments of the present invention have been described above. Through the above description, relevant staff can make various changes and modifications completely within the scope of not deviating from the technical idea of this invention.

Claims

1. A method for setting the maximum front and rear axle loads of a passenger car, characterized in that, It includes the following steps: In step S1, specific key design parameters are obtained; the specific key design parameters include curb weight, center of gravity position, maximum design gross mass, wheelbase, track width, wheel center coordinates; the curb weight includes basic curb weight and maximum curb weight; In step S2, under the unloaded state, the front and rear axle loads are calculated and obtained; the unloaded state includes the basic curb weight state and the maximum curb weight state; In step S3, the loading point position coordinates are obtained and a loading model is established; the loading point position coordinates include seat loading point coordinates and trunk loading point coordinates; In step S4, based on the loading model, curb weight, front and rear axle loads under unloaded state, and maximum design gross mass, with the basic curb weight and the maximum curb weight as the benchmarks respectively, loading is carried out according to the preset loading method and the front and rear axle loads are calculated accordingly to form an axle load matrix; In step S5, the obtained axle load matrix is analyzed, the maximum values of the front axle load and the rear axle load are screened out, and the maximum front axle load and the maximum rear axle load are obtained according to the preset correction method; The preset loading method includes a loading method of loading to the minimum design gross mass and a loading method of loading to the maximum design gross mass; The loading method of loading to the minimum design gross mass includes: Loading method 1: Each seat is loaded with the mass of a single passenger respectively, and the mass loaded in the trunk is the product of the standard luggage mass and the number of passengers; Loading method 2: Each seat is loaded with the sum of the mass of a single passenger and the standard luggage mass, and the mass loaded in the trunk is zero; The loading method of loading to the maximum design gross mass includes: Loading method 3: Each seat is loaded with the mass of a single passenger respectively, and goods are loaded into the trunk until the maximum design gross mass is reached; Loading method 4: Each seat in the first row and each seat in the second row are loaded with the mass of a single passenger respectively, the third row seats are folded, and goods are loaded on the rear floor of the second row until the maximum design gross mass is reached; Loading method 5: Each seat in the first row and each seat in the second row are loaded with the sum of the mass of a single passenger and the standard luggage mass, the third row seats are folded, and goods are loaded on the rear floor of the second row until the maximum design gross mass is reached; The preset correction method is: determining the axle load correction coefficient according to the estimated deviation of the vehicle center of gravity position, and obtaining the maximum front axle load and the maximum rear axle load according to the axle load correction coefficient.

2. The method for setting the maximum front and rear axle loads of a passenger car according to claim 1, wherein In step S2, the basic curb weight includes: the mass of the basic power transmission system, the mass of all standard assembly plant installed standard parts and accessories, the mass of the cargo box, the calculated mass of the liquid in the passenger car, the mass when the fuel in the fuel tank reaches a preset ratio; the maximum curb weight is the sum of the basic curb weight and the maximum optional parts mass.

3. A method for setting the maximum front and rear axle loads of a passenger car according to claim 1, characterized in that, In step S3, the measurement in the vehicle digital model obtains the measured wheel center coordinates, the measured seat H-point, and the measured trunk loading point. When establishing the loading model, the coordinate points are symmetrically processed and the weight loading point coordinates are obtained according to the national standard of the automotive H-point determination procedure; the loading point positions include the left of the first row of seats, the right of the first row of seats, the left of the second row of seats, the middle of the second row of seats, the right of the second row of seats, the left of the third row of seats, the right of the third row of seats, the 7-seat loading point of the trunk, and the 5-seat loading point of the trunk. In step S4, the mass of a single passenger and the mass of standard luggage are set according to the national standard requirements.

4. The method for setting the maximum front and rear axle loads of a passenger car according to claim 1, wherein It further includes the following steps: In step S6, the vehicle models are classified according to the powertrain adopted by the vehicle models, and the same set of maximum front axle load and maximum rear axle load are set for the same type of vehicle models.

5. A method for setting the maximum front and rear axle loads of a passenger car as described in claim 1, characterized in that, In step S2, according to the lever balance principle, the unloaded front and rear axle loads are calculated according to the following formula: M 后轴 = M * X / L; M 前轴 = M - M 后轴 ; Among them, M 后轴 is the rear axle load, M 前轴 is the front axle load, X is the distance from the vehicle center of mass to the front axle; L is the vehicle wheelbase; M is the curb weight.

6. The method for setting the maximum front and rear axle loads of a passenger car according to claim 1, characterized in that, In step S4, a calculation system is established. After the user inputs vehicle parameters through the calculation system interface and visually sets the loading method, the calculation system calculates and outputs axle load data and wheel load data.

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