Optimization design method for seat cushion with hollow air duct

Abstract

The present invention relates to an optimization design method for a seat cushion with hollow air ducts. The optimization design method includes the steps of S1, drawing a fluid simulation model grid of the seat cushion; S2, determining the model coefficients of the fluid simulation model grid; S3, designing the number, diameter and position of the hollow air ducts; S4, designing an orthogonal simulation experiment of the hollow air ducts and establishing an orthogonal simulation experiment table; S5, dividing the air layer into multiple flow investigation areas; S6, calculating the ventilation uniformity of the seat cushion; S7, fitting the factor index function relationship; S8, setting optimization conditions; S9, solving the total ventilation volume and ventilation uniformity. The present invention proposes an optimization design method for a seat cushion with hollow air ducts, which realizes the coordinated optimization of the total ventilation volume and ventilation uniformity of the seat cushion by reasonably setting the number, position and diameter of the hollow air ducts.

Description

Technical Field

[0001] The invention relates to the technical field of vehicle computer-aided engineering design, and in particular to an optimization design method for a seat cushion with a hollow air duct. Background Art

[0002] With the improvement of living standards, people's expectations for seat functions are also increasing. In the automotive industry, fully functional car seats have become standard for high-end cars. Seats with ventilation functions are favored by consumers because they can quickly provide coolness in the hot summer. Figure 1 The schematic diagram of the structure of a seat cushion with a hollow air duct. As shown in the figure, the seat cushion 100 includes a fan 101, a support layer 102, a foam structure 103 and a hollow air duct 104. When the seat ventilation function is turned on, the fan 101 applies positive or negative pressure to the air by sucking or blowing air, the support layer 102 and the hollow air duct 104 together constitute an air circulation channel, and the dense foam structure 103 constitutes an airtight wall surface. The air flows along the channel and takes away the heat from the human body. When designing a seat cushion with a hollow air duct 104, the total ventilation volume must reach a certain value, and the ventilation volume of each part of the contact area between the human buttocks and the seat cushion should be uniform, so as to achieve the effect of rapid heat dissipation. Figure 2 The top view of the seat cushion with the hollow air duct is shown in FIG. The optimization of the total flow rate and the uniformity of the contact area can be achieved by reasonably arranging the position, number and diameter of the hollow air duct 104 .

[0003] At present, the design of total ventilation volume and ventilation uniformity of seat cushions is usually based on engineers' experience to adjust the hollow air duct. This optimization method based on subjective judgment has the following limitations:

[0004] ①This optimization method has weak directionality and large accidental components;

[0005] ② Unable to find the most reasonable air duct layout;

[0006] ③ The method has poor reference value, and the optimized case lacks guidance for the design of other cases.

[0007] Based on the above limitations, the design of seat cushions with hollow air ducts requires a more scientific and reasonable design method. In addition, the traditional optimization design method usually obtains the performance of the design scheme through experiments, and each modification requires the seat cushion mold to be modified, which is costly, time-consuming and labor-intensive. Summary of the invention

[0008] In view of the above problems in the prior art, the present invention proposes an optimization design method for a seat cushion with hollow air ducts, which achieves the coordinated optimization of the total ventilation volume and ventilation uniformity of the seat cushion by reasonably setting the number, position and diameter of the hollow air ducts.

[0009] Specifically, the present invention proposes an optimization design method for a seat cushion with a hollow air duct, comprising the steps of:

[0010] S1, dividing the seat cushion into an air layer, a hollow air duct and a support layer from top to bottom, and drawing a fluid simulation model grid of the seat cushion according to the division result;

[0011] S2, determining the model coefficients of the fluid simulation model grid;

[0012] S3, designing the number, diameter and position of the hollow air duct according to the distance between the support layer and the fan;

[0013] S4, designing an orthogonal simulation experiment of the hollow air duct according to the design result of step S3, the ventilation uniformity and the total ventilation volume of the hollow air duct, and establishing an orthogonal simulation experiment table;

[0014] S5, dividing the air layer into a plurality of flow investigation areas, and obtaining the ventilation flow of the flow investigation areas according to the orthogonal simulation experiment;

[0015] S6, calculating the ventilation uniformity of the seat cushion;

[0016] S7, factor-indicator function relationship fitting;

[0017] Fit the functional relationship between the number, diameter and position of the hollow air ducts and the ventilation uniformity based on the orthogonal simulation experiment table and the ventilation uniformity calculation result; fit the functional relationship between the number, diameter and position of the hollow air ducts and the ventilation flow rate based on the orthogonal simulation experiment table and the total ventilation volume;

[0018] S8, setting optimization conditions for the total ventilation volume and ventilation uniformity of the seat cushion;

[0019] S9, solving the total ventilation volume and ventilation uniformity of the seat cushion according to the optimization conditions.

[0020] According to one embodiment of the present invention, in step S1, the air layer includes an air layer unit, a peripheral shell unit and a top shell unit, the peripheral shell unit surrounds the periphery and bottom of the air layer unit, the top shell unit is arranged on the top of the air layer unit, and the fluid simulation model grids of the air layer unit, the peripheral shell unit and the top shell unit are drawn separately;

[0021] The hollow air duct comprises an air duct body unit and an air duct surface shell unit, the air duct surface shell unit is arranged around the air duct body unit, and the fluid simulation model grids of the air duct body unit and the air duct surface shell unit are drawn separately;

[0022] The support layer includes a support layer surface shell unit, a support layer body unit and a fan shell unit. The support layer surface shell unit is arranged at the top, bottom and periphery of the support layer unit, and the fan shell unit is arranged on the side of the support layer body unit close to the fan. The fluid simulation model grids of the support layer surface shell unit, the support layer body unit and the fan shell unit are drawn separately.

[0023] According to one embodiment of the present invention, the density of the grid of the fluid simulation model of each part of the air layer, the hollow air duct and the supporting layer is consistent with the changing gradient of the flow field, and the junction position of the hollow air duct and the supporting layer is encrypted; the vertical projection size of the air layer is consistent with the contact range of the dummy's buttocks and legs with the seat cushion.

[0024] According to one embodiment of the present invention, in step S2, the viscous resistance coefficient and the inertial resistance coefficient of the support layer in each direction are measured, comprising the steps of:

[0025] S21, taking the pressure flow curve of the fan at the first speed as the model input;

[0026] S22, according to the orthogonal table Set 8 different sets of viscous drag coefficients and inertial drag coefficients;

[0027] S23, obtaining the total ventilation volume of simulation results of 8 groups of different viscous drag coefficients and inertial drag coefficients;

[0028] S24, fitting a relationship function between the viscous drag coefficient, the inertial drag coefficient and the total ventilation volume of the fan at the first speed;

[0029] S25, repeating steps S21 to S24 to respectively fit the relationship functions between the viscous drag coefficient, the inertial drag coefficient and the total ventilation volume of the fan at the second to sixth speeds;

[0030] S26, the total ventilation volume of the seat cushion at six speed levels of the fan is recorded in the matrix TE, and the viscous drag coefficient and the inertial drag coefficient of the seat cushion in different directions are calculated through the matrix TE.

[0031] According to one embodiment of the present invention, in step S3, the support layer is divided into n regions according to the distance from the fan, the width of each region is twice the maximum allowable diameter of the hollow air duct, and Ni hollow air ducts equally divided in the length direction of the region are placed in the i-th region, the diameters of the hollow air ducts are equal, and the total number of the hollow air ducts is ∑N i .

[0032] According to one embodiment of the present invention, in step S4, the hollow air duct ni in the i-th area and the air duct diameter Ri in the i-th area are taken as factors, and the ventilation uniformity and total ventilation volume of the hollow air duct are taken as indicators to design an orthogonal simulation experiment of the hollow air duct, and an orthogonal simulation experiment table is established.

[0033] According to an embodiment of the present invention, in step S5, the air layer is evenly divided into m*m flow investigation areas, and the ventilation flow of each flow investigation area is obtained according to the orthogonal simulation experiment.

[0034] According to one embodiment of the present invention, in step S6, the flow uniformity H is calculated according to the ventilation flow obtained in step S5:

[0035] H=-∑(P i )(lnP i );

[0036] Pi is the proportion of ventilation flow in the ith flow inspection area to the total ventilation flow;

[0037] The flow uniformity is calculated for all the orthogonal simulation experiment results listed in the orthogonal simulation experiment table.

[0038] According to one embodiment of the present invention, in step S8, the optimization condition includes:

[0039] The number Ni of hollow air ducts in each region is an integer between 1 and Nmax, N i ∈{1,2,…,N max};

[0040] The diameter Ri of each hollow air duct is within the maximum allowable diameter R max and minimum diameter R min Between, R min ≤R i ≤R max ;

[0041] If the number of hollow air ducts in a certain area is 0, the diameter of the hollow air duct in the area is 0;

[0042] The total ventilation volume of the seat cushion must be greater than the total ventilation volume Fd required by the design, F(N,R)>F d .

[0043] According to one embodiment of the present invention, a non-dominated sorting genetic algorithm with an elite strategy is used to solve a multi-objective optimization model of the total ventilation volume and ventilation uniformity of the seat cushion.

[0044] The present invention provides an optimization design method for a seat cushion with a hollow air duct, which achieves the coordinated optimization of the total ventilation volume and ventilation uniformity of the seat cushion by reasonably setting the number, position and diameter of the hollow air duct.

[0045] It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The accompanying drawings are included to provide further explanation of the present invention, and they are incorporated into and constitute a part of this application. The accompanying drawings illustrate embodiments of the present invention and together with this specification serve to explain the principles of the present invention. In the accompanying drawings:

[0047] Figure 1 It is a schematic diagram of the structure of a seat cushion with a hollow air duct.

[0048] Figure 2 A top view of a seat cushion with a hollow air duct.

[0049] Figure 3 A flowchart of a method for optimizing the design of a seat cushion with a hollow air duct according to an embodiment of the present invention is shown.

[0050] Figure 4 A schematic diagram of a fluid simulation model grid according to an embodiment of the present invention is shown.

[0051] Figure 5 A schematic diagram showing an air layer according to an embodiment of the present invention.

[0052] Figure 6 A schematic diagram of the division structure of a hollow air duct according to an embodiment of the present invention is shown.

[0053] Figure 7 A schematic structural diagram of a flow inspection area according to an embodiment of the present invention is shown.

[0054] Figure 8 A schematic diagram of the division structure of a hollow air duct according to an embodiment of the present invention is shown.

[0055] The above drawings include the following reference numerals:

[0056] Seat cushion 100, 400

[0057] Fan 101, 414

[0058] Support layer 102, 408

[0059] Foam structure 103

[0060] Hollow air duct 104, 405

[0061] Air layer 401

[0062] Air layer unit 402

[0063] Peripheral Shell Element 403

[0064] Top shell element 404

[0065] Air duct unit 406

[0066] Duct Surface Shell Element 407

[0067] Support layer surface shell element 409

[0068] Support layer unit 410

[0069] Fan housing unit 411

[0070] Hip 412

[0071] Legs 413

[0072] Traffic survey area 415

[0073] Air duct optimization area 416 DETAILED DESCRIPTION

[0074] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application may be combined with each other.

[0075] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present application and its application or use. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0076] 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.

[0077] Unless otherwise specifically stated, the relative arrangement, numerical expressions and numerical values ​​of the parts and steps set forth in these embodiments do not limit the scope of the application. Meanwhile, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to actual proportional relationships. The technology, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be considered as a part of the specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, and therefore, once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0078] In the description of the present application, it should be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction, and therefore cannot be understood as limiting the scope of protection of the present application; the directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0079] In addition, it should be noted that the use of words such as "first" and "second" to define components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above words have no special meaning and cannot be understood as limiting the scope of protection of this application. In addition, although the terms used in this application are selected from well-known and commonly used terms, some terms mentioned in the specification of this application may be selected by the applicant at his or her discretion, and their detailed meanings are explained in the relevant parts of the description of this article. In addition, it is required to understand this application not only by the actual terms used, but also by the meaning implied by each term.

[0080] Figure 3The flowchart of the optimization design method of the seat cushion with hollow air duct according to one embodiment of the present invention is shown. As shown in the figure, the present invention provides an optimization design method of the seat cushion with hollow air duct, and the optimization design method comprises the following steps:

[0081] S1, dividing the seat cushion into an air layer, a hollow air duct and a support layer from top to bottom, and drawing a fluid simulation model grid of the seat cushion according to the division result;

[0082] S2, determining the model coefficients of the fluid simulation model grid;

[0083] S3, design the number, diameter and position of the hollow air ducts according to the distance between the support layer and the fan;

[0084] S4, designing an orthogonal simulation experiment of the hollow air duct according to the design result of step S3, the ventilation uniformity and the total ventilation volume of the hollow air duct, and establishing an orthogonal simulation experiment table;

[0085] S5, dividing the air layer into a plurality of flow investigation areas, and obtaining the ventilation flow of the flow investigation areas according to an orthogonal simulation experiment;

[0086] S6, calculate the ventilation uniformity of the seat cushion;

[0087] S7, factor-indicator function relationship fitting;

[0088] Based on the orthogonal simulation experiment table and the ventilation uniformity calculation results, the functional relationship between the number, diameter and position of the hollow air duct and the ventilation uniformity is fitted; based on the orthogonal simulation experiment table and the total ventilation volume, the functional relationship between the number, diameter and position of the hollow air duct and the ventilation flow rate is fitted;

[0089] S8, setting the optimization conditions of the total ventilation volume and ventilation uniformity of the seat cushion;

[0090] S9, solve the total ventilation volume and ventilation uniformity of the seat cushion according to the optimization conditions.

[0091] Figure 4 A schematic diagram of a fluid simulation model grid according to an embodiment of the present invention is shown. Figure 5 FIG. 1 is a schematic diagram showing an air layer of an embodiment of the present invention. Figure 4 As shown, the seat cushion 400 includes an air layer 401, a hollow air duct 405 and a support layer 408. In step S1, the air layer 401 includes an air layer body unit 402, a peripheral shell unit 403 and a top shell unit 404. The peripheral shell unit 403 surrounds the periphery and bottom of the air layer body unit 402, and the top shell unit 404 is set on the top of the air layer body unit 402. The fluid simulation model meshes of the air layer body unit 402, the peripheral shell unit 403 and the top shell unit 404 are drawn separately.

[0092] The hollow air duct 405 includes an air duct body unit 406 and an air duct surface shell unit 407. The air duct surface shell unit 407 is arranged around the air duct body unit 406, and the fluid simulation model grids of the air duct body unit 406 and the air duct surface shell unit 407 are drawn separately.

[0093] The support layer 408 includes a support layer surface shell unit 409, a support layer body unit 410 and a fan shell unit 411. The support layer surface shell unit 409 is arranged at the top, bottom and periphery of the support layer 408 unit, and the fan shell unit 411 is arranged on the side of the support layer body unit 410 close to the fan 414. The fluid simulation model grids of the support layer surface shell unit 409, the support layer body unit 410 and the fan shell unit 411 are drawn separately.

[0094] Preferably, the density of the mesh of the fluid simulation model of each part of the air layer 401, the hollow air duct 405 and the support layer 408 is consistent with the change gradient of the flow field. The mesh density is increased (encrypted) at the junction of the hollow air duct 405 and the support layer 408. The mesh density is also increased at the position of the sudden change of shape. Figure 5 The vertical projection size of the air layer 401 is consistent with the contact range between the dummy's buttocks 412 and legs 413 and the seat cushion 400 .

[0095] Preferably, in step S2, since the support layer 408 is composed of a foaming medium, it is necessary to measure the viscous resistance coefficient and the inertial resistance coefficient of the support layer 408 in each direction, including the steps of:

[0096] S21, taking the pressure flow curve (PQ curve) of the fan 414 at the first speed as the model input.

[0097] S22, according to the orthogonal table Set 8 different sets of viscous drag coefficients and inertial drag coefficients. Refer to Table 1 below, dx, dy and dz represent the viscous drag coefficients in the x, y and z directions respectively, and fx, fy and fz represent the inertial drag coefficients in the x, y and z directions respectively.

[0098] Table 1 Setting table of viscous drag coefficient and inertial drag coefficient of fan 414 at the first speed

[0099]

[0100] S23, obtaining the total ventilation volume of simulation results of 8 groups of different viscous drag coefficients and inertial drag coefficients;

[0101] S24, fit the relationship function between the viscous drag coefficient, inertial drag coefficient and total ventilation volume of the fan at the first speed:

[0102] T(d,f)1=a 11 dx+a 21 dy+a 31 dz+a 41 fx+a 51 fy+a 61 fz+a 71 Formula (1);

[0103] Wherein, T(d,f)1 represents the total ventilation volume of the fan at the first speed, a11 to a61 are coefficients of the relationship function, and a71 is the constant term coefficient.

[0104] S25, repeating steps S21 to S24 to respectively fit the relationship functions between the viscous drag coefficient, the inertial drag coefficient and the total ventilation volume of the fan at the second to sixth speeds.

[0105] S26, recording the total ventilation volume TE1-TE6 of the seat cushion 400 at six speed levels of the fan into the matrix TE;

[0106] TE=[TE1, TE2, TE3, TE4, TE5, TE6] T ;

[0107] The viscous drag coefficient and the inertial drag coefficient of the seat cushion 400 in different directions are calculated by combining Formula 2;

[0108]

[0109] Where K is the drag coefficient matrix [dx,dy,dz,fx,fy,fz] T , B is the constant term coefficient matrix.

[0110] Figure 6 The schematic diagram of the division structure of the hollow air duct of an embodiment of the present invention is shown. Preferably, as shown in the figure, in step S3, the support layer 408 is divided into n areas from near to far according to the distance from the fan 414, and the direction shown in the figure is divided into n areas from left to right. The width of each area is the same, and the width of each area is twice the maximum allowable diameter of the hollow air duct 405. In the i-th area, Ni hollow air ducts 405 are placed in an even division in the length direction of the area, and the diameters of the hollow air ducts 405 are equal. The total number of hollow air ducts 405 is ∑N i .

[0111] Preferably, in step S4, the hollow air duct 405ni in the i-th area and the air duct diameter Ri in the i-th area are used as factors, and there are 2n factors in total. The ventilation uniformity and total ventilation volume of the hollow air duct 405 are used as indicators to design an orthogonal simulation experiment of the hollow air duct 405, and an orthogonal simulation experiment table is established.

[0112] According to the orthogonal table, an orthogonal experimental table with factors greater than or equal to 2n+1 is selected for the experiment. For example, if the hollow air duct 405 is divided into 3 areas in step S4, an orthogonal table with 2 levels and 7 factors can be selected. Orthogonal array The factor characterizing the diameter of the hollow air duct 405 is horizontally distributed as the equal points between the maximum allowable diameter Dmax and the minimum allowable diameter Dmin. The factor representing the number of hollow air ducts 405 has a level distribution between 1 and the maximum allowed number Nmax. For , its factor level distribution is shown in Table 2, and its orthogonal simulation experiment table is shown in Table 3.

[0113] Table 2 Factor level distribution table

[0114]

[0115] Table 3 Orthogonal simulation experiment table

[0116]

[0117] Figure 7 The schematic diagram of the structure of the flow inspection area of ​​an embodiment of the present invention is shown. As shown in the figure, preferably, in step S5, the air layer 401 is evenly divided into m*m flow inspection areas 415. In this embodiment, the air layer 401 is evenly divided into 5*5 flow inspection areas 415 to form the 1st to 25th flow inspection areas 415, and the ventilation flow of each flow inspection area 415 is obtained according to the orthogonal simulation experiment.

[0118] Preferably, in step S6, after the ventilation flow rate is obtained in step S5, the flow uniformity H is calculated by the Shannon-Wiener index formula:

[0119] H=-∑(P i )(lnP i ) formula (3);

[0120] Pi is the ratio of the ventilation flow rate of the i-th flow inspection area 415 to the total ventilation flow rate;

[0121] The flow uniformity is calculated for all orthogonal simulation experiment results listed in the orthogonal simulation experiment table.

[0122] Preferably, in step S7, the functional relationship between the number, diameter and position of the hollow air duct 405 and the ventilation uniformity is fitted based on the orthogonal simulation experiment table and the ventilation uniformity calculation result, and is expressed as:

[0123] Among them, m i , g i and l is the function coefficient;

[0124] Based on the orthogonal simulation experiment table and the total ventilation volume, the functional relationship between the number, diameter and position of the hollow air duct 405 and the ventilation flow rate is fitted and expressed as:

[0125] Among them, x i ,y i and z are the function coefficients.

[0126] Preferably, the optimization conditions in step S8 include:

[0127] The number Ni of the hollow air ducts 405 in each area is an integer between 1 and Nmax, N i ∈{1,2,…,N max};

[0128] Subject to the constraints of the manufacturing process, the diameter Ri of each hollow air duct 405 is within the maximum allowable diameter R max and minimum diameter R min Between, R min ≤R i ≤R max ;

[0129] If the number of hollow air ducts 405 in a certain area is 0, then the diameter of the hollow air duct 405 in the area is 0, which can be expressed as: i =0, then R i =0;

[0130] The total ventilation volume of the seat cushion 400 must be greater than the total ventilation volume Fd required by the design, expressed as the formula: F(N,R)>F d .

[0131] Preferably, a non-dominated sorting genetic algorithm (NSGAⅡ) with an elite strategy is used to solve a multi-objective optimization model of the total ventilation volume and ventilation uniformity of the seat cushion 400, specifically including:

[0132] First, an initial population of size Q is generated, followed by a fast non-dominated sort, and then selection, crossover and mutation operations are performed on the initial population to obtain the first-generation subpopulation.

[0133] The steps of fast non-dominated sorting are as follows:

[0134]

[0135] For the set F2 of individuals with Pareto level 2, step S3 is repeated, and so on until all population levels are divided.

[0136] The selection operation of the genetic algorithm adopts the binary tournament selection method, the crossover operation adopts the real number coded crossover operation, and the mutation operation adopts the polynomial mutation operation.

[0137] Starting from the second generation, the elite retention strategy is implemented to merge the parent population with the child population, perform fast non-dominated sorting, and calculate the crowding degree of individuals in each non-dominated layer. According to the non-dominated relationship and the crowding degree of the individuals, suitable individuals are selected to form a new parent population.

[0138] The selection strategy of the new parent population is as follows:

[0139] 1. According to the order of Pareto level from low to high, put the whole layer population into the parent population until the individuals in the K layer cannot be put into the parent population;

[0140] 2. Arrange the individuals in this layer from large to small according to the degree of crowding, and put them into the parent population one by one until the parent population is full.

[0141] Finally, a new offspring population is generated through the basic operations of the genetic algorithm, and so on, until the conditions for the end of the fast non-dominated program are met.

[0142] Figure 8 The schematic diagram of the division structure of the hollow air duct of an embodiment of the present invention is shown. The optimization design method of a seat cushion with a hollow air duct provided by the present invention is applied to a rear ventilated seat cushion 400 of a certain car. The ventilation volume design requirement of the designed hollow air duct 405 is greater than 200L / min. Based on the analysis of the actual ventilation effect, it is determined Figure 8 The air duct optimization area 416 in the middle is used to optimize the number, diameter and position of the hollow air duct 405 in the area 416 to achieve a better total ventilation volume and ventilation uniformity of the hollow air duct 405. The initial ventilation volume of this embodiment is 140 L / min, and the ventilation uniformity is 2.065.

[0143] According to step S1 , a fluid simulation model grid of the seat cushion 400 is drawn according to the air layer 401 , the hollow air duct 405 and the support layer 408 .

[0144] Step S2, determining the viscous drag coefficient and inertial drag coefficient of the support layer 408 in each direction. The simulation results of the ventilation volume of the fan 414 at different viscous drag coefficients and inertial drag coefficients at the first speed are shown in Table 4 below.

[0145] Table 4 Simulation results of ventilation volume under different viscous drag coefficients and inertial drag coefficients at the first speed of fan 414

[0146]

[0147] According to the results in Table 4, the functional relationship between the resistance coefficient and the total ventilation volume is as follows:

[0148] T(d,f)1=-4.176dx-4.289dy-7.762dz-0.024fx-0.020fy-0.024fz+743.461.

[0149] Similarly, the functional relationship between the viscous drag coefficient, the inertial drag coefficient and the ventilation volume at the 2nd to 6th speed of the fan 414 is fitted, and the resistance and ventilation volume relationship coefficient matrix is ​​formed as follows:

[0150]

[0151] The constant term coefficient matrix B and the experimental result matrix TE are as follows:

[0152] B=(743.461 755.751 760.405 766.448 771.124 770.452) T ;

[0153] TE=(92.248 118.425 152.785 169.258 176.542 194.456) T ;

[0154] The constructed viscous drag coefficient and inertial drag coefficient are used to solve the multivariate linear equation system as follows:

[0155]

[0156] The resistance coefficient matrix K of the support layer 408 obtained by solving the above equations is:

[0157] K=(46.577 755.751 760.405 766.448 771.124 770.452) T

[0158] exist Figure 8 Three air duct layout areas are divided in the air duct optimization area 416 in the figure. A positive cross table with 2 levels and 7 factors is selected. As a basis, an orthogonal experiment is designed. The horizontal distribution table of the layout factors of the hollow air duct 405 of a rear seat cushion 400 of a certain car and the orthogonal simulation experiment table are shown in Table 5 and Table 6 respectively. The number of air ducts that can be placed in the three air duct arrangements is 1 and 3, and the air duct diameter is 5 and 20.

[0159] Table 5 Horizontal distribution of layout factors of rear hollow air duct 405 of a certain car

[0160]

[0161] Table 6 Orthogonal experiment table of 405 layout of hollow air duct in the rear row of a certain car

[0162]

[0163] The total ventilation flow of each orthogonal experimental group obtained by ParaView software and the ventilation uniformity calculated based on the flow ratio of the flow investigation area 415 are shown in Table 7.

[0164] Table 7 Calculation results of total ventilation volume and ventilation uniformity of seat cushion 400 ventilation

[0165]

[0166] The functional relationship between the number, diameter and position of the hollow air duct 405 of the seat cushion 400 and the ventilation uniformity and the total ventilation volume based on the regression fitting of the data in Table 7 is as follows:

[0167] H(N, R)=0.027N1+0.047N2+0.048N3-0.035R1-0.023R2-0.011R3+3.615;

[0168] F(N,R)=34.7N1+13.6N2+10.1N3+3.8R1+0.9R2+0.7R3+65.2.

[0169] Python programming is used to solve the non-dominated sorting genetic algorithm. The number of iterations is set to 100 times, the population size is 10, the number of hollow air ducts 405 in the placement area of ​​each hollow air duct 405 and the diameter of each air duct are used as optimization factors, and the optimization results obtained with ventilation uniformity and coordination of ventilation volume and uniformity as the goals are shown in Table 8 below.

[0170] Table 8 Comparison of optimization results

[0171]

[0172]

[0173] According to the optimization results in Table 8, compared with the initial solution, when only ventilation uniformity is used as the optimization target, the uniformity is improved by 58.98%, and the total ventilation volume is improved by 68.3%; when ventilation uniformity and total ventilation volume are used as the targets, the ventilation uniformity in the optimization results is improved by 51.86%, and the total ventilation volume is improved by 82.55%.

[0174] Comparing the optimization results, we can see that:

[0175] 1. The proposed multi-objective collaborative optimization method for the total ventilation volume and ventilation uniformity of the seat cushion based on the number, diameter and position of the hollow air ducts can greatly improve the total ventilation volume and ventilation uniformity of the seat cushion;

[0176] 2. Compared with the single-objective optimization of ventilation uniformity, the multi-objective collaborative optimization of total ventilation volume and ventilation uniformity has a smaller improvement in uniformity optimization, but the total ventilation volume optimization can be greatly improved. Therefore, it is necessary to carry out multi-objective collaborative optimization.

[0177] From the above, the optimization design method of the seat cushion with a hollow air duct provided by the present invention has the following advantages compared with the prior art:

[0178] 1. Only a few non-destructive experiments need to be conducted on the basis of the existing design, and then fluid simulation can be carried out on this basis, which saves time and effort, reduces the ineffective mold opening costs in the optimization process, and reduces development costs;

[0179] 2. The total ventilation volume and ventilation uniformity of the seat cushion can be optimized by reasonably setting the number, position and diameter of the hollow air ducts.

[0180] It will be apparent to those skilled in the art that various modifications and variations may be made to the above exemplary embodiments of the present invention without departing from the spirit and scope of the present invention. Therefore, it is intended that the present invention covers modifications and variations of the present invention that fall within the scope of the appended claims and their equivalent technical solutions.

Claims

1. A method for optimizing the design of a seat cushion with a hollow air duct, comprising the steps of: S1, dividing the seat cushion into an air layer, a hollow air duct and a support layer from top to bottom, and drawing a fluid simulation model grid of the seat cushion according to the division result; S2, determining the model coefficients of the fluid simulation model grid; S3, designing the number, diameter and position of the hollow air duct according to the distance between the support layer and the fan; S4, designing an orthogonal simulation experiment of the hollow air duct according to the design result of step S3, the ventilation uniformity and the total ventilation volume of the hollow air duct, and establishing an orthogonal simulation experiment table; S5, dividing the air layer into a plurality of flow investigation areas, and obtaining the ventilation flow of the flow investigation areas according to the orthogonal simulation experiment; S6, calculating the ventilation uniformity of the seat cushion; S7, factor-indicator function relationship fitting; Fit the functional relationship between the number, diameter and position of the hollow air ducts and the ventilation uniformity based on the orthogonal simulation experiment table and the ventilation uniformity calculation result; fit the functional relationship between the number, diameter and position of the hollow air ducts and the ventilation flow rate based on the orthogonal simulation experiment table and the total ventilation volume; S8, setting optimization conditions for the total ventilation volume and ventilation uniformity of the seat cushion; S9, solving the total ventilation volume and ventilation uniformity of the seat cushion according to the optimization conditions.

2. The optimization design method according to claim 1, characterized in that: In step S1, the air layer includes an air layer unit, a peripheral shell unit and a top shell unit, wherein the peripheral shell unit surrounds the periphery and bottom of the air layer unit, and the top shell unit is arranged on the top of the air layer unit, and the fluid simulation model grids of the air layer unit, the peripheral shell unit and the top shell unit are drawn separately; The hollow air duct comprises an air duct body unit and an air duct surface shell unit, the air duct surface shell unit is arranged around the air duct body unit, and the fluid simulation model grids of the air duct body unit and the air duct surface shell unit are drawn separately; The support layer includes a support layer surface shell unit, a support layer body unit and a fan shell unit. The support layer surface shell unit is arranged at the top, bottom and periphery of the support layer unit, and the fan shell unit is arranged on the side of the support layer body unit close to the fan. The fluid simulation model grids of the support layer surface shell unit, the support layer body unit and the fan shell unit are drawn separately.

3. The optimization design method according to claim 2, characterized in that: The density of the fluid simulation model grid of each part of the air layer, hollow air duct and support layer is consistent with the change gradient of the flow field, and the junction position of the hollow air duct and the support layer is encrypted; the vertical projection size of the air layer is consistent with the contact range between the dummy's buttocks and legs and the seat cushion.

4. The optimization design method according to claim 1, characterized in that: In step S2, the viscous resistance coefficient and the inertial resistance coefficient of the support layer in each direction are measured, including the steps of: S21, taking the pressure flow curve of the fan at the first speed as the model input; S22, according to the orthogonal table L 7 2. Set 8 different sets of viscous drag coefficients and inertial drag coefficients; S23, obtaining the total ventilation volume of simulation results of 8 groups of different viscous drag coefficients and inertial drag coefficients; S24, fitting a relationship function between the viscous drag coefficient, the inertial drag coefficient and the total ventilation volume of the fan at the first speed; S25, repeating steps S21 to S24 to respectively fit the relationship functions between the viscous drag coefficient, the inertial drag coefficient and the total ventilation volume of the fan at the second to sixth speeds; S26, the total ventilation volume of the seat cushion at six speed levels of the fan is recorded in the matrix TE, and the viscous drag coefficient and the inertial drag coefficient of the seat cushion in different directions are calculated through the matrix TE.

5. The optimization design method according to claim 1, characterized in that: In step S3, the support layer is divided into n regions according to the distance from the fan, the width of each region is twice the maximum allowable diameter of the hollow air duct, and N equally divided regions in the length direction are placed in the i-th region. i Hollow air ducts, the diameters of the hollow air ducts are equal, and the total number of the hollow air ducts is ∑N i .

6. The optimization design method according to claim 5, characterized in that: In step S4, the hollow air duct ni in the i-th area and the air duct diameter R in the i-th area are used. i Taking the ventilation uniformity and total ventilation volume of the hollow air duct as factors, the orthogonal simulation experiment of the hollow air duct is designed, and an orthogonal simulation experiment table is established.

7. The optimization design method according to claim 1, characterized in that: In step S5, the air layer is evenly divided into m*m flow investigation areas, and the ventilation flow of each flow investigation area is obtained according to the orthogonal simulation experiment.

8. The optimization design method according to claim 7, characterized in that: In step S6, the flow uniformity H is calculated according to the ventilation flow obtained in step S5: H=-∑(P i )(lnP i ); P i is the ratio of the ventilation flow rate of the ith flow inspection area to the total ventilation flow; The flow uniformity is calculated for all the orthogonal simulation experiment results listed in the orthogonal simulation experiment table.

9. The optimization design method according to claim 6, characterized in that: In step S8, the optimization conditions include: The number N of hollow air ducts in each of the regions i From 1 to N max An integer between i ∈{1,2,…,N max }; The diameter R of each hollow air duct i The maximum permissible diameter R max and minimum diameter R min Between, R min ≤R i ≤R max ; If the number of hollow air ducts in a certain area is 0, the diameter of the hollow air duct in the area is 0; Based on the orthogonal simulation experiment table and the total ventilation volume, the functional relationship between the number, diameter and position of the hollow air duct and the ventilation flow rate is fitted and expressed as: x i ,y i and z are function coefficients; The total ventilation volume of the seat cushion must be greater than the total ventilation volume F required by the design d ,F(N,R)>F d .

10. The optimization design method according to claim 9, characterized in that: A non-dominated sorting genetic algorithm with an elite strategy is used to solve the multi-objective optimization model of the total ventilation volume and ventilation uniformity of the seat cushion.

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