A design method and a design terminal for a multi-stage stiffness rear leaf spring of a light truck

Abstract

The application provides a light truck multi-stage stiffness rear leaf spring design method and a design terminal, and relates to the technical field of light truck spring suspension. The multi-stage stiffness leaf spring does not have overlapping contact between pieces, the length of each piece decreases from bottom to top, the main spring is fixed with a spring eye and a support through a leaf spring pin to realize hinging, each auxiliary spring cooperates with a cantilever support arranged on a vehicle frame to realize step-by-step contact of each piece of auxiliary spring, realize a multi-stage nonlinear elastic characteristic curve, and adapt to comfort improvement under various loadings. The application provides a specific theoretical design method to ensure that the stiffness of each piece of leaf spring takes into account the comfort requirements of each loading state, ensure that the service life of each piece of leaf spring meets the bench fatigue frequency requirements, ensure that the arc height of each piece of leaf spring is set to be consistent under full load, and ensure that the setting of the spacer between the auxiliary spring cantilever support and the leaf spring avoids the extreme bounce of the leaf spring without piece-to-piece contact. The application effectively ensures the smoothness and reliability of the light truck.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of light truck spring suspension, in particular to a light truck multi-stage stiffness rear leaf spring design method and design terminal. BACKGROUND

[0002] Light truck refers to the N2 type vehicle in the N type classification of vehicle type, and the maximum design total mass of the N2 type vehicle is not greater than 4.5 tons. Since the light truck is smaller than the large truck, the flexibility is just right, and the light truck can transport small tonnage goods, so that the light truck has been widely used in the transportation industry. The suspension spring of the light truck is an elastic element in the automobile suspension, which elastically connects the light truck axle and the light truck frame or the vehicle body, bears and transmits the vertical load, and moderates and suppresses the impact caused by the uneven road surface.

[0003] The traditional rear longitudinal composite steel plate spring suspension system is commonly two-stage stiffness main and auxiliary spring structure, the auxiliary spring is above or below, and the main spring and the auxiliary spring work by contact and superposition of each leaf spring piece. Due to the influence of Coulomb friction damping between the pieces, the friction work will cause unpredictable and uncontrollable between the equivalent dynamic stiffness and the design stiffness, and the dynamic-static ratio is often large, especially under the condition of empty and full load small amplitude, which affects the smoothness of the road, and even low-frequency resonance problem occurs.

[0004] The full load arc heights of the leaf springs of the rear longitudinal composite steel plate spring suspension system are different after contact, which causes the user to worry about the load bearing. Moreover, the leaf spring pieces of the traditional rear longitudinal composite steel plate spring suspension system contact with each other at any working stroke, and the superimposed stress produces unexpected dry friction, which affects the smoothness. SUMMARY

[0005] The present application provides a light truck multi-stage stiffness rear leaf spring design method, which can reduce the reliability risk of the design, and make the light truck multi-stage stiffness rear leaf spring design form industrial application.

[0006] The parameters for configuring and calculating the light truck multi-stage stiffness rear leaf spring are configured, and the parameters include: wheelbase L, empty load frequency f k , full load frequency f m , empty load axle load G1, full load axle load G2, half load axle load state one G 12 , half load axle load state two G 23 , rear axle non-sprung load G m , empty load single side spring load F k , half load single side spring load F 12 , half load single side spring load F 23 , full load single side spring load F m , and the first piece of the empty load auxiliary spring and the corresponding suspension arm limiting distance Δ1 (the limiting distance is designed by combining the standard deviation of the vehicle operating condition experience deflection and the required collision limiting probability with the normal distribution table).

[0007] The design process involves the main spring length L 主 A secondary piece of long L f1 Sub-n film length L fn n is a positive integer. Clamping distance L 夹 β clamping ineffectiveness coefficient, thickness h at the end of the main spring coil. ZD The thickness h at the root of the main spring ZG Thickness h at one end of the sub-assembly FD1 The thickness h of the secondary root FG1 ..., thickness h at the end of the sub-n FDn , the thickness of the root of the secondary n is h FGn .

[0008] The method for designing and calculating the main spring parameters in this invention includes the following steps:

[0009] S101: Input no-load offset frequency f from the design k and unloaded spring F k Determine the main spring clamping stiffness C 主 Calculate using the following formula

[0010]

[0011] The single-sided spring load is half of the unsprung axle load excluding the unsprung load. The calculation of the single-sided spring load in other states is the same as the above formula.

[0012] C 主 =(2πf k ) 2 F k

[0013] S102: Main spring length L 主 Determined by the wheelbase L, the length of the rear suspension main leaf spring is generally L for N2 class vehicles. 主 Select within the following range

[0014] 0.35L≤L 主 ≤0.4L

[0015] N3 category vehicles rear suspension main spring length L 主 Select within the following range

[0016] 0.25L≤L 主 ≤0.35L

[0017] S103: In stepped spring suspension systems, all spring plates have the same width b. N2 type spring plates are typically 70mm or 75mm wide, while N3 type spring plates are 75mm or 90mm wide.

[0018] S104: Based on the fatigue life requirements of the leaf spring technical specifications, the main spring has a lower specific stress than the leaf spring. It should meet the following scope

[0019]

[0020] S105: Based on the yield stress requirements in the technical specifications for leaf spring materials, the ultimate stroke H of the leaf spring is determined by the following formula.

[0021]

[0022] Where δ s Let μ be the yield strength of the material, and μ be the safety factor, typically taken as 1.1.

[0023] S106: Leaf springs will bend during use, and the arc height will decrease over time. To prevent reverse bending under full load and static load, a certain full load arc height f is often set. a The full-load arc height is generally taken as

[0024] 10mm≤f a ≤20mm

[0025] S107: Static deflection of the main spring is f c The dynamic deflection is f d Static deflection is the deformation under full load, and dynamic deflection is the deformation under full load to the ultimate reverse bow. The two parameters satisfy the following formula:

[0026]

[0027] Where 5≤α≤6

[0028] Main spring arc height H 主 (The main spring is designed with a flattened arc height, without considering the coiled ear type) is determined by the following formula.

[0029] H 主 =f c +f a

[0030] S108: Fully loaded spring-loaded F m Effective length of leaf spring l e Specific stress of the main spring Calculate the thickness h at the root of the leaf spring ZG To maximize weight reduction, the thickness is typically rounded up to the smallest integer. The calculation formula is as follows:

[0031]

[0032] Among them, L e =L 主 -β·L 夹

[0033] β is the clamping ineffectiveness coefficient; L 夹 Leaf spring clamping distance

[0034] S109: Because the main spring is provided with the eye structure at both ends, the main spring eye end needs to bear the function of transmitting longitudinal force in addition to vertical support. Generally, the rear axle is a drive axle. The maximum stress of the front half of the main spring of the leaf spring under the maximum driving force working condition should be checked. The stress should meet the condition that it is not greater than 350 MPa. The specific calculation formula can be referred to in "Automobile Chassis Design". The thickness h of the eye end of the main spring is determined accordingly. ZD For lightweight design, the minimum thickness of the end part under the stress condition is generally selected.

[0035] In summary, by adjusting the length of the straight section of the eye end through the existing mature design method of the few-leaf spring parabolic structure, the main spring stiffness C 主 that meets the design requirements is obtained.

[0036] The design and calculation of the parameters of each leaf of the secondary spring include the following steps:

[0037] S201: Assembly stiffness design: the assembly clamping stiffness C 总 is determined by the design input full load frequency f m and full load spring load F m . The following formula is used for calculation

[0038] C 总 = (2πf m ) 2 F m

[0039] Where C 总 = C 主 + C f1 + C f2 + … + C fn

[0040] C f1 is the clamping stiffness of the first leaf of the secondary spring from bottom to top, and C fn is the clamping stiffness of the nth leaf of the secondary spring from bottom to top

[0041] S202: Design of the arc height of each leaf: under the no-load load state of the leaf spring, the distance between the first leaf of the secondary spring and the corresponding secondary spring cantilever limiting arm is Δ1, the distance between the second leaf of the secondary spring and the corresponding secondary spring cantilever limiting arm is Δ2, and the distance between the nth leaf of the secondary spring and the corresponding secondary spring cantilever limiting arm is Δ n In order to realize the consistency of the arc height of each leaf when all the leaf springs work at the same time or the last leaf of the secondary spring just works, the arc height of each leaf, the secondary spring limiting distance of each cantilever, and the arc height of each leaf of the secondary spring have the following relationship:

[0042]

[0043] Where H f1The arc height of the first leaf of the secondary spring is designed, H fn The arc height of the nth leaf of the secondary spring is designed, and the designed arc height is the arc height change from the free state to the flattened state of the leaf spring. H0 is the arc height change in the unloaded state of the main spring, H0 = F k ·g / c 主 .

[0044] The secondary spring and the corresponding secondary spring cantilever limiting distance is determined: Δ1 is determined by the standard deviation of the vehicle operating condition experience deflection, the required collision limiting probability, and the normal distribution table design limiting distance. The recommended value is 8-10mm on good roads. Δ2...Δ n The following relationship needs to be met:

[0045]

[0046] Where F 12 , F 23 are the concerned loads in the use state of the leaf spring, which are design inputs, and generally not more than two states, such as half-load state, in which the leaf spring assembly has a secondary spring not in contact with the corresponding secondary spring cantilever. Unlike traditional two-stage springs or even single-piece springs, this can effectively reduce the stiffness and natural frequency in this specific state, improving comfort. Since the main spring is a single-piece spring, to avoid excessive stress on the main spring under full load, which may cause driving risks, it is recommended that 5mm≤Δ n+1 -Δ n ≤10mm.

[0047] S203: Design of the stiffness of each leaf of the secondary spring:

[0048]

[0049] C f3 which can be obtained by simultaneously solving the formula in step S201.

[0050] S204: Design of the length of each leaf of the secondary spring:

[0051] The length of each leaf of the secondary spring decreases from bottom to top. The length of each leaf of the secondary spring should be as long as possible. Under the same deflection condition, the longer the length of the leaf spring, the smaller the change in curvature, the smaller the stress change, and the longer the service life of the leaf spring.

[0052] The length of the first leaf of the secondary spring cannot be too long, and the vertical movement of the front and rear leaf spring supports during movement and the movement space under brake torsion should be ensured. It is recommended that L 主 -L f1≥ 350 mm. The length difference between each piece of the secondary spring is the same, and the recommended value is 100 mm≤ AL≤ 150 mm. The ineffective length at both ends of the secondary spring is the same. The ineffective length mainly ensures that the vertical movement deformation of the leaf spring and the corresponding cantilever of the secondary spring are always in contact and force. The ineffective length avoids the leaf spring from being completely separated under full load in each working condition. The movement check is based on finite element simulation. The recommended unilateral ineffective length is [30, 40].

[0053] S205: Design of the thickness of each piece of the secondary spring:

[0054] In order to reduce the dry friction with the corresponding cantilever of the secondary spring, reduce the dynamic-static ratio, and improve the smoothness, the secondary spring is designed to have a hole at the effective length point of each piece and is assembled with an embedded nylon gasket. The friction coefficient can be reduced from 0.3-0.5 to 0.1-0.15. In order to use the nylon gasket, the thickness of the end part is set to be the same.

[0055] The multi-stage stiffness ladder leaf spring gradually contacts the corresponding cantilever of the secondary spring from the main spring in the horizontal jump movement. The main spring is always under load. The working frequency of each level of the secondary spring decreases in turn. The uppermost end of the secondary spring has the lowest action frequency. Therefore, the specific stress of each level of the leaf spring increases from bottom to top. Under the premise that the length of the leaf spring piece gradually shortens and the stiffness meets the design value of S203, the service life of the assembly can be controlled. The greater the specific stress, the greater the unit deformation stress change, and the shorter the service life of the leaf spring. The service life is designed according to the use frequency, which achieves the purpose of reducing redundant structure and lightweight design.

[0056] Recommended value of specific stress of each piece of the secondary spring (the specific stress of the secondary spring should not be greater than 25 MPa / mm, which limits the number of secondary springs):

[0057] The first piece of the secondary spring: 12≤ δ f1 ≤ 15 (MPa / mm)

[0058] The second piece of the secondary spring: 16≤ δ f2 ≤ 19 (MPa / mm)

[0059] The third piece of the secondary spring: 20≤ δ f3 ≤ 23 (MPa / mm)

[0060] …

[0061] According to the recommended value of the specific stress, the root thickness of each piece of the secondary spring can be calculated. Through the existing mature few-piece spring parabolic structure design method, the length of the flat section at the end is adjusted to obtain the stiffness of each level of the secondary spring that meets the design requirements.

[0062] The design and calculation of the parameters of the spring piece-to-piece gasket include the following steps:

[0063] Due to the variable cross-section parabolic structure design of each piece, there is no contact between the pieces except for the contact of the flat root section, and from the compression of each piece to the limit of the reverse arch, the length of the secondary spring gradually decreases, the arc height changes the same, the curvature radius becomes smaller, the gap between the ends of the adjacent pieces becomes smaller, and until the contact interference. In order to avoid the contact interference to generate dry friction and affect the smoothness, the gasket between the pieces needs to meet the following requirements:

[0064] H 反 = H - H 主

[0065]

[0066]

[0067]

[0068]

[0069]

[0070] Wherein H 反 is the arc height change of the main spring from compression to the limit of the reverse arch;

[0071] Wherein h 主 is the thickness of the gasket between the main spring and the first piece of the secondary spring;

[0072] Wherein h1 is the thickness of the gasket between the first piece of the secondary spring and the second piece of the secondary spring;

[0073] Wherein h (n-1) is the thickness of the gasket between the nth piece of the secondary spring and the n-1th piece of the secondary spring;

[0074] Wherein R f1 is the curvature radius after the reverse arch H 反 of the first piece of the secondary spring;

[0075] Wherein R fn is the curvature radius after the reverse arch H 反 of the first piece of the secondary spring.

[0076] From the above technical solutions, the present application has the following advantages:

[0077] The light truck multi-stage stiffness rear leaf spring design method provided by the application solves the problem that the traditional rear longitudinal composite steel plate spring suspension system is commonly provided with a two-stage stiffness main and auxiliary spring structure, the auxiliary spring is above or below, the main spring and the auxiliary spring work by contact and superposition of each leaf spring piece, the Coulomb friction damping between the pieces is affected, and the problem that the equivalent dynamic stiffness and the design stiffness are difficult to predict and control is caused. Through the application, the full contact of each stage leaf spring under full load can be realized, and the user's worry about load bearing can be avoided. Through the application, the piece-to-piece contact of each leaf spring piece at any working stroke can be avoided, and the smoothness affected by the unexpected dry friction generated by the superimposed stress can be avoided.

[0078] The application combines the piece-to-piece non-overlapping contact of the multi-stage stiffness leaf spring, the piece length of each piece decreases in turn from bottom to top, the main spring is fixed by the leaf spring pin, the leaf spring eye and the bracket are hinged, each auxiliary spring is matched with the cantilever bracket arranged on the frame to realize the step-by-step contact of each piece auxiliary spring, realize the multi-stage nonlinear elastic characteristic curve, and adapt to the comfort improvement under various loads.

[0079] The light truck multi-stage stiffness rear leaf spring design method provided by the application can guarantee the stiffness of each piece of leaf spring and consider the comfort requirements of each load state, guarantee the service life of each piece of leaf spring to meet the bench fatigue frequency requirements, make the arc height setting of each piece of leaf spring meet the consistency of full load arc height of each piece of leaf spring under full load, guarantee the setting of the pad between the auxiliary spring cantilever bracket and the leaf spring to avoid the piece-to-piece contact of the leaf spring under extreme bounce. The light truck multi-stage stiffness rear leaf spring design method guarantees the smoothness and reliability of the light truck design.

[0080] Moreover, the application can calculate the structure size and stiffness performance parameters of each stage according to the smoothness deviation frequency and load bearing demand, guarantee the service life of each stage leaf spring to decrease according to the use frequency from bottom to top, avoid weight redundancy through the lightweight design, improve the economy, and guarantee the step-by-step contact of each stage leaf spring with the cantilever through the design of the application, realize the nonlinear design of the leaf spring stiffness, and greatly guarantee the comfort under each working condition. BRIEF DESCRIPTION OF DRAWINGS

[0081] In order to more clearly illustrate the technical solutions of the application, the drawings needed to be used in the description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creating laborious work.

[0082] Fig. 1 The light truck multi-stage stiffness rear leaf spring design method flowchart;

[0083] Fig. 2 The elastic characteristic curve schematic diagram of the designed multi-stage stiffness rear leaf spring;

[0084] Fig. 3 Structure diagram for designing corresponding multi-stage stiffness rear leaf spring.

[0085] Figure 1 is a structure diagram for designing corresponding multi-stage stiffness rear leaf spring. Fig. 3 In the figure, 1 is a first piece of main spring; 2 is a first piece of auxiliary spring; 3 is a second piece of auxiliary spring; 4 is a third piece of auxiliary spring; 5 is a piece pad between the first piece of main spring and the first piece of auxiliary spring; 6 is a piece pad between the first piece of auxiliary spring and the second piece of auxiliary spring; 7 is a piece pad between the second piece of auxiliary spring and the third piece of auxiliary spring; 8 is an arc height of main spring; 9 is a spacing between the first piece of auxiliary spring and a corresponding suspension arm; 10 is a corresponding suspension arm of the first piece of auxiliary spring; 11 is a corresponding suspension arm of the second piece of auxiliary spring; 12 is a corresponding suspension arm of the third piece of auxiliary spring; 13 is an arc height of the first piece of auxiliary spring; 14 is an effective length of the third piece of auxiliary spring; and 15 is a length of main spring. DETAILED DESCRIPTION

[0086] As shown in the figure, the light truck multi-stage stiffness rear leaf spring designed by the design method of the application is applied to a longitudinal steel plate spring non-independent suspension rear suspension. Figs. 1 to 3 The design method of the application is applied to symmetric leaf springs with left and right equal length structures, and can also be applied to equal width leaf springs with each piece having equal width structure.

[0087] The application relates to a multi-stage stiffness leaf spring, and each stage of stiffness is realized by a single piece of leaf spring.

[0088] Before design, the following parameters are configured in advance: wheelbase L, empty load deflection frequency f k , full load deflection frequency f m , empty load axle load G1, full load axle load G2, half load axle load state one G 12 , half load axle load state two G 23 , rear axle non-spring load G m , empty load single-side spring load F k , half load single-side spring load F 12 , half load single-side spring load F 23 , full load single-side spring load F m , empty load auxiliary spring first piece and corresponding suspension arm spacing Δ1 (a spacing designed by combining standard deviation of deflection and required collision limiting probability of vehicle operation condition experience with normal distribution table).

[0089] The design process involves main spring piece length L 主 ; auxiliary first piece length L f1 , auxiliary n piece length L fn , n is a positive integer. Clamping distance L 夹 , β clamping invalidity coefficient, main spring ear end thickness h ZD , main spring root thickness h ZG , auxiliary first end thickness h FD1 , auxiliary first root thickness h FG1..., the sub-n end portion thickness h FDn , the sub-n root portion thickness h FGn .

[0090] The light truck multi-stage stiffness rear leaf spring design method provided by the application can acquire and process associated data based on artificial intelligence technology. The numerical control machine tool intelligent diagnosis method driven by digital twinning utilizes a digital computer or a machine controlled by a digital computer to simulate, extend and expand human intelligence, perceive the environment, acquire knowledge, and use the knowledge to obtain the best results. The method also has a machine learning function, wherein the machine learning and deep learning in the method of the application generally include artificial neural networks, belief networks, reinforcement learning, transfer learning, inductive learning, and rule-based learning.

[0091] The light truck multi-stage stiffness rear leaf spring design method is applied to one or more design terminals, which is a device capable of automatically performing numerical calculation and / or information processing according to pre-set or stored instructions. The hardware thereof includes but is not limited to microprocessors, application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), digital signal processors (DSPs), embedded devices, etc.

[0092] The design terminal can be any electronic product that can interact with the user, such as a personal computer, a tablet computer, a smartphone, a personal digital assistant (PDA), an interactive Internet Protocol Television (IPTV), etc.

[0093] The design terminal can also include network devices and / or user devices. The network devices include, but are not limited to, a single network server, a server group composed of multiple network servers, or a cloud composed of a large number of hosts or network servers based on cloud computing.

[0094] The network in which the design terminal is located includes but is not limited to the Internet, a wide area network, a metropolitan area network, a local area network, a virtual private network (VPN), etc.

[0095] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0096] The present application will be further described in detail through the following embodiments.

[0097] 1. The vehicle is a light blue card truck, the wheelbase L = 3280 mm, the empty rear axle load G1 = 1178 kg, the rear axle half load state one G12 = 1728 kg, the rear axle half load state two G23 = 2426 kg, the full load rear axle load G2 = 5747 kg, the non-spring load Gm = 458 kg, the empty frequency deviation fk = 3.02 Hz, the full load frequency deviation fm = 2.6 Hz, and the leaf spring clamping distance Lclamping = 150 mm.

[0098] According to the vehicle market segmentation and application scene analysis setting, the first piece of the empty auxiliary spring and the corresponding cantilever limiting distance Δ1 = 9 mm. There are four load states of interest, which can be realized by four pieces of spring to achieve four levels of stiffness.

[0099] 2. Main spring clamping stiffness calculation, only main spring works in empty state, empty unilateral spring load C 主 = (2πf k ) 2 F k = 130 N / mm.

[0100] 3. According to the vehicle wheelbase L = 3280 mm, the wheelbase range 0.35L ≤ L 主 ≤ 0.4L, it can be known that 1148 mm ≤ L 主 ≤ 1312 mm, the longer the piece length, the better the reliability can be obtained, and the main spring piece length L 主 = 1300 mm is selected.

[0101] 4. The total mass of the light blue card truck is not more than 4.5T, and the conventional width b of the leaf spring is 70 mm.

[0102] 5. According to the main spring piece spring stress ratio The main spring is a commonly used spring steel, the yield strength is 1200 MPa, the safety factor μ ≥ 1.1, and the limit travel of the leaf spring The limit travel H of the selected leaf spring is 115 mm.

[0103] 6. The full load static deflection fc and the leaf spring dynamic deflection fd can be calculated from the full load static deflection fc calculation formula.

[0104] Wherein 5≤α≤6, the coefficient α is determined, and the full load camber fc=70mm and the plate spring deflection fd=45mm can be obtained.

[0105] 7. Design camber height H of main spring 主 = f c + f a , wherein 10mm≤f a ≤20, f a is the full load camber, f a =15mm, H 主 =85mm, and the design camber height does not consider the form of the main spring eyelet.

[0106] 8. Effective length calculation of main spring: L e =L 主 -β·L 夹 , wherein β is the clamping invalidity coefficient, and is 0.5;

[0107] L The clamping distance of L clamp plate spring is 150mm, and L e =1225mm is known, which is brought into the formula The root thickness h ZG of the main spring can be calculated as h ZG ≥19.9mm, and h ZD =20mm is taken after rounding.

[0108] 9. According to the existing mature design method, the rear axle is a drive axle, and the maximum stress of the plate spring main spring in the front half section under the maximum driving force working condition is checked, and the stress should not be greater than 350MPa, so that the end thickness h ZD of the plate spring can be determined as h ZD =11mm.

[0109] According to the above calculation data, the full load stress of the full load main spring is calculated as which basically meets the requirement of the full load stress of the main spring.

[0110] Other parameters of the main spring can be calculated by the mature method of few pieces of variable cross-section in chassis design.

[0111] 10. Through the full load frequency fm=2.6Hz and the full load single-side spring load Fm=2644..5kg,

[0112] The clamping stiffness C of the plate spring assembly can be calculated by the following formula 总 =(2πf m ) 2 F m =705N / mm.

[0113] 11. According to H 主 =85mm, Δ1=9mm, H0=F k ·g / C 主 =27mm,

[0114] H0+ Δ1= 49 mm f1 H0+ Δ1= 49 mm 主 H0+ Δ1= 49 mm f1 H0+ Δ1= 49 mm H0+ Δ1= 49 mm

[0115] H0+ Δ1= 49 mm fn H0+ Δ1= 49 mm 主 H0+ Δ1= 49 mm n H0+ Δ1= 49 mm H0+ Δ1= 49 mm

[0116] 12、According to G12= 1728 kg, F12= 635 kg; according to G23= 2426 kg, F23= 984 kg. Through the formula

[0117] The first piece of the secondary spring clamping stiffness C f1 = 256 N / mm, the second piece of the secondary spring clamping stiffness C f2 = 180 N / mm; from the above calculation, the total clamping stiffness of the leaf spring assembly C 总 = 705 N / mm, then C f3 = C 总 = C f1 = C f2 = C 主 = 139 mm

[0118] (H0+ Δ1)·C 主 ≤ F 12 · g ≤ (H0+ Δ1)·C 主 + (Δ2- Δ1)·(C 主 + C f1 )

[0119] Calculate Δ2- Δ1≥ 4 mm,

[0120] 13、From

[0121] (H0+ Δ1)·C 主 + (Δ2- Δ1)·(C 主 + C f1 ) ≤ F 23 · g ≤ (H0+ Δ1)·C 主 + (Δ2- Δ1)·(C 主 + C f1 ) + (Δ3- Δ2- Δ1)·(C 主 + C f1 + C f2 )

[0122] Calculate Δ2- Δ1≤ 13 mm.

[0123] From the recommended 5 mm ≤ Δ n+1 - Δ nFor thicknesses ≤10mm, Δ2 = 16mm and Δ3 = 23mm can be selected to meet the requirements.

[0124] 14. The length of each leaf of the auxiliary spring can be determined by L. 主 -L f1 ≥350mm, where L 主 =1300mm, the effective length L of the first leaf of the auxiliary spring can be selected. f1 =1000mm, the effective length L of the second leaf of the auxiliary spring can be selected by using 100mm≤ΔL≤150mm. f2 =870mm, effective length L of the third leaf of the auxiliary spring f3 =870mm. Based on the recommended single-sided ineffective length [30,40], the straightened lengths of each leaf of the auxiliary spring can be selected as 1080mm, 930mm, and 800mm respectively.

[0125] 15. Based on the recommended specific stress values ​​of each auxiliary spring, the specific stresses of each auxiliary spring are selected as follows: 13.5 MPa / mm; 17.5 MPa / mm; 21 MPa / mm.

[0126] From step 8 The root thickness h of each auxiliary spring can be determined. ZGn L is the thickness at the root of the nth leaf of the auxiliary spring. en Let n be the effective length of the nth leaf of the auxiliary spring. Let be the specific stress of the nth leaf of the auxiliary spring.

[0127] The thickness of the root of each leaf of the auxiliary spring can be selected as 20mm, 14mm, or 10mm.

[0128] The thickness of each leaf of the auxiliary spring is the same at the end, which can be selected as 8mm. By using the existing mature design method for variable cross-section leaf springs with fewer leaves, the calculated stiffness of each stage of the auxiliary spring can be obtained by adjusting the length of the straight section at the end.

[0129] 16. According to H 反 =HH 主 Where H = 115 mm, H 主 =85mm can be used to calculate H 反 =30mm.

[0130] Depend on R can be calculated 主 =7042mm.

[0131] From the formula The thickness h at the root of the first leaf of the auxiliary spring FG1 =20mm, thickness h at the end of the first leaf of the auxiliary spring FD1 =8mm, so the thickness h of the spacer between the main spring and the first leaf of the auxiliary spring can be determined. 主 ≥5.25mm.

[0132] From the formula Wherein R f1 = 4167mm, the secondary spring second piece root thickness h FG2 = 14mm, the secondary spring second piece end thickness h FD2 = 8mm, it can be known that the secondary spring first piece and the secondary spring second piece pad thickness h1≥6.3mm.

[0133] From the formula Wherein R f2 = 3154mm, the secondary spring third piece root thickness h FG3 = 10mm, the secondary spring third piece end thickness h FD3 = 8mm, it can be known that the secondary spring second piece and the secondary spring third piece pad thickness h2≥11.3mm.

[0134] The above design calculation can determine the structure design of the multi-stage stiffness leaf spring of the light truck, and the leaf spring calculated according to the above steps can guarantee the design input load and performance requirements while being the lightest in weight.

[0135] It should be understood that the size of the serial number of each step in the above embodiment does not mean the order of execution, and the execution order of each process should be determined according to its function and internal logic, and should not constitute any limitation on the implementation process of the embodiment of the present application.

[0136] The present application can collect the design parameters of the multi-stage stiffness rear leaf spring of the light truck, facilitate the design personnel to perform add, delete, modify and query operations, effectively adjust the design process data, meet the design requirements, and improve the design efficiency. It can also efficiently collect, store and process design parameters, monitor the design process of the multi-stage stiffness rear leaf spring of the light truck, use multi-dimensional space to describe the entire design process, improve design accuracy, timely detect abnormal problems in the design process and make adjustments to improve the level and efficiency of the design process, control the risk of the design process, and thus realize the timeliness and scientificity of the supervision, management and control of the entire design process.

[0137] The units and algorithm steps of each example described in the embodiments disclosed in the light truck multi-stage stiffness rear leaf spring design method provided by the present application can be realized by electronic hardware, computer software or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. Whether the described functions are executed in hardware or software mode depends on the specific application and design constraints of the technical solution. Professional technicians can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

[0138] It should be understood that all the systems, devices and methods disclosed herein can be implemented in other ways. For example, the device embodiments described above are merely schematic, and the division of the units is merely a logical function division. In actual implementation, another division manner can be adopted, for example, a plurality of units or components can be combined or integrated into another system, or some features can be omitted or not executed. In addition, the coupling or direct coupling or communication connection between the units shown or discussed can be indirect coupling or communication connection through some interfaces, devices or units, and can also be electrical, mechanical or other forms of connection.

[0139] In addition, the described features, structures or characteristics can be combined in one or more embodiments. In the following description, numerous specific details are provided to give a thorough understanding of embodiments of the application. One skilled in the relevant art will recognize, however, that the application can be practiced without one or more of the specific details, or with other methods, components, devices, steps, etc. In other instances, well-known methods, devices, implementations or operations are not shown or described in detail to avoid obscuring aspects of the application.

[0140] The computer program code for carrying out operations of the present disclosure can be written in one or more programming languages or combinations of languages including object or visual programming languages such as Java, Smalltalk, C++ or conventional procedural programming languages such as the "C" programming language or similar programming languages. The program code can execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer can be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection can be made to an external computer (for example, through the Internet using an Internet Service Provider).

[0141] The above description of disclosed embodiments provides enabling or useful information to a person skilled in the art to implement or use the application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the application. Therefore, the application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method of designing a multi-stage stiffness rear leaf spring for a light truck, characterized by, The method comprises: S1, configure parameters for calculating multi-stage stiffness rear leaf spring of light truck, the parameters including: wheelbase L, empty load frequency f k , full load frequency f m , empty load axle load G1, full load axle load G2, half load axle load state one G 12 , half load axle load state two G 23 , rear axle unsprung load G m , empty load single side spring load F k , half load single side spring load F 12 , half load single side spring load F 23 , full load single side spring load F m , and the limiting distance Δ1 of the first piece of empty load auxiliary spring and the corresponding cantilever S2, design and calculate the main spring parameters; S3, design and calculate the parameters of each piece of the secondary spring; The method for designing and calculating the parameters of each piece of the secondary spring comprises the following steps: S201: Design assembly stiffness: input loaded natural frequency f m and loaded spring rate F m Determine assembly clamp stiffness C 总 by the following equation C 总 = (2πf m ) 2 F m where C 总 = C 主 + C f1 + C f2 +... + C fn C f1 Cn-1is the clamping stiffness of the (n-1)th leaf of the lower leaf spring from bottom to top fn Cn is the clamping stiffness of the nth leaf of the lower leaf spring from bottom to top S202: design the height of each piece: under the condition of the plate spring empty load, the distance between the first piece of the secondary spring and the corresponding first piece of the secondary spring limiting cantilever is Δ1, the distance between the second piece of the secondary spring and the corresponding second piece of the secondary spring limiting cantilever is Δ2, and the distance between the nth piece of the secondary spring and the corresponding nth piece of the secondary spring limiting cantilever is Δn. n ; Each piece has the same full load arc height, the cantilever limiting distance of each piece of the secondary spring, and the arc height of each piece of the secondary spring has the following relationship: H f1 is the design arc height of the first piece of the secondary spring fn is the design arc height of the nth piece of the secondary spring, the design arc height being the arc height change from the free state to the flattened state of the leaf spring; H0 is the arc height change in the unloaded state of the primary spring, H0 = F k · g / C 主 ; The cantilever limiting distance of the secondary spring and the corresponding secondary spring is determined: Δ1 is 8-10 mm; Δ2... Δ n satisfies the following relationship: where F 12 , F 23 are the loads of interest in the use condition of the leaf spring, respectively; 5 mm < Δ n+1 - Δ n ≤ 10 mm; S4, design and calculate the parameters of the spring piece and the pad, and obtain the light truck cargo vehicle leaf spring; The full load camber f is set a The full load camber is taken 10 mm < f a ≤ 20 mm The main spring static deflection is f c , the dynamic deflection is f d , the static deflection is the full load deformation, and the dynamic deflection is the full load to limit reverse arch deformation; the two parameters satisfy the following formula: Wherein 5≤α≤6 Main spring arc height H 主 is calculated from the equation H 主 = f c + f a F = F + F m , the effective length of the leaf spring l e , the specific stress of the main spring Calculate the thickness of the leaf spring root h ZG , the calculation formula is as follows: wherein L e = L 主 - β · L 夹 β is the clamping inefficiency coefficient; L 夹 is the plate spring clamping distance.

2. The method of claim 1, wherein, The method for designing and calculating the parameters of the main spring comprises the following steps: S101: Obtain the unloaded frequency offset f k , and calculate the unloaded spring rate F k and the main spring clamping stiffness C 主 respectively by the following formula C 主 = (2πf k ) 2 F k S102: main spring length L 主 The main spring length L of the rear suspension of the N2 type vehicle is determined by the wheelbase L 主 In the following range 0.35L ≤ L 主 ≤ 0.4L N3 class vehicle rear suspension main spring piece length L 主 In the following ranges 0.25L ≤ L 主 ≤ 0.35L.

3. The light truck cargo vehicle multi-stage stiffness rear leaf spring design method according to claim 2, characterized in that, S103: The widths b of each piece of the stepped spring suspension system are the same, the width of the N2 type piece is 70 mm, and the width of the N3 type piece is 75 mm and 90 mm; S104: main spring leaf spring specific stress Falls within the following ranges; S105: The limit travel H of the leaf spring is determined by the following formula where δ s is the yield limit of the material, and μ is a safety factor, taken as 1.

1.

4. The light truck cargo vehicle multi-stage stiffness rear leaf spring design method according to claim 1, characterized in that, Check the maximum stress of the front half of the main spring of the leaf spring under the maximum driving force condition, and determine the thickness h of the end of the main spring eye ZD , select the minimum thickness of the end that meets the stress condition; Adjusting the length of the flat section of the ear end to obtain the main spring stiffness C that meets the design requirements 主 .

5. The light truck cargo vehicle multi-stage stiffness rear leaf spring design method according to claim 1, characterized in that, S203: Design the stiffness parameters of each piece of the secondary spring: C f3 are obtained from the simultaneous solution of equations (2.1); S204: Design the length of each piece of the secondary spring: L 主 L f1 ≥ 350 mm; The adjacent difference value of the length of each piece of the secondary spring is 100 mm≤ΔL≤150 mm; Single-side invalid length [30, 40].

6. The light truck cargo vehicle multi-stage stiffness rear leaf spring design method according to claim 5, characterized in that, S205: Design the thickness of each piece of the secondary spring: The recommended value of the specific stress of each piece of the secondary spring is: Secondary spring first piece: 12 ≤ δ f1 ≤ 15 (MPa / mm) Secondary spring second leaf: 16 ≤ δ f2 ≤ 19 (MPa / mm) Secondary spring third piece: 20 ≤ δ f3 ≤ 23 (MPa / mm) …… According to the above recommended value of the specific stress, the root thickness of each piece of the secondary spring is calculated.

7. The light truck cargo vehicle multi-stage stiffness rear leaf spring design method according to claim 1 or 2, characterized in that, The method for designing and calculating the parameters of the spring piece and the pad comprises the following steps: H 反 = H-H 主 where H 反 is the change in arc height of the main spring flattened to the reverse bow limit; where h 主 is the thickness of the shim between the primary spring and the first piece of the secondary spring; Wherein h1 is the thickness of the pad between the first piece of the secondary spring and the second piece of the secondary spring; where h (n-1) is the shim thickness between the nth leaf of the secondary spring and the (n-1)th leaf of the secondary spring; wherein R f1 is the radius of curvature of the first leaf of the secondary spring H 反 after the reverse bow where R fn is the radius of curvature of the first leaf of the secondary spring after the counter-bow H 反 .

8. A design terminal comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, The processor implements the steps of the light truck cargo vehicle multi-stage stiffness rear leaf spring design method according to any one of claims 1 to 7 when executing the program.

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