CN112507486A

CN112507486A - Method for checking key parameters of unequal-length few-leaf oblique-line-type variable-section plate spring

Info

Publication number: CN112507486A
Application number: CN202011365409.5A
Authority: CN
Inventors: 周长城; 杨林; 郑伟; 耿向阳; 许金兵
Original assignee: Shandong Automobile Spring Factory Zibo Co ltd; Shandong University of Technology
Current assignee: Shandong Automobile Spring Factory Zibo Co ltd; Shandong University of Technology
Priority date: 2020-11-28
Filing date: 2020-11-28
Publication date: 2021-03-16
Anticipated expiration: 2040-11-28
Also published as: CN112507486B

Abstract

The invention relates to a checking method of a non-isometric few-leaf oblique line type variable cross-section plate spring, and belongs to the technical field of vehicle suspension few-leaf variable cross-section plate springs. The method can check the clamping rigidity, the suspension offset frequency, the stress intensity, the initial tangent arc height and the maximum limit deflection of the unequal-length few-leaf oblique line type variable-section plate spring according to the design structure parameters, the elastic modulus, the rated load, the allowable stress under the rated load and the maximum allowable stress under the impact load of the given plate spring. According to a prototype test, the checking method of the unequal-length few-leaf oblique-line-type variable-section plate spring is correct, the clamping rigidity, the suspension offset frequency, the initial arc height and the maximum limiting deflection of the designed plate spring are ensured to meet the design requirements of the plate spring, and the design level and performance of the unequal-length few-leaf oblique-line-type variable-section plate spring and the driving smoothness and safety of a vehicle are improved; meanwhile, the test cost of the product is reduced, and the product development speed is accelerated.

Description

Method for checking key parameters of unequal-length few-leaf oblique-line-type variable-section plate spring

Technical Field

The invention relates to a few-leaf variable-section plate spring of a vehicle suspension, in particular to a method for checking key parameters of a non-isometric few-leaf diagonal variable-section plate spring.

Background

The half-symmetrical structure of the few-leaf oblique line type variable cross-section plate spring is composed of a root straight section, an oblique line section and an end straight section, and the two ends of the cross section of the half-symmetrical structure are in a shape of an arc, a chamfer or a right angle. In order to further reduce the weight of the plate spring with less variable cross section and meet the design requirements of suspension offset frequency and plate spring rigidity, a few-piece oblique line type variable cross section plate spring with unequal length is usually adopted, wherein the lengths of oblique line segments and end straight segments of all the plate springs are unequal, and the thickness of the end straight segment of the first plate spring is larger than that of the end straight segments of other plate springs. However, the stiffness of each leaf spring of the unequal-length few-leaf oblique line type variable-section leaf spring is not equal, and the calculation of the clamping stiffness is very complicated in consideration of the shapes of two ends of the cross section and the influence on the stiffness. According to the checked data, for the unequal-length few-leaf oblique-line type variable-section plate spring with given design structure parameters, due to the restriction of clamping rigidity calculation and load distribution of each leaf spring, a checking method for key parameters of the unequal-length few-leaf oblique-line type variable-section plate spring is not provided at home and abroad at present, so that the design requirements of suspension offset frequency, initial arc height and maximum limit deflection of the designed plate spring are difficult to ensure. Therefore, an accurate and reliable checking method for key parameters of the unequal-length few-leaf diagonal variable-section plate spring is required to be established, so that the key parameters of the plate spring are ensured to meet the design requirements of the plate spring, and the product quality and performance of the product and the driving smoothness and safety of a vehicle are improved; meanwhile, the test cost of the product is reduced, and the product development speed is accelerated.

Disclosure of Invention

In view of the above-mentioned drawbacks in the prior art, the technical problem to be solved by the present invention is to provide an accurate and reliable method for checking key parameters of a leaf spring with variable cross-section and less inclined pieces of unequal lengths, wherein a design flow chart is shown in fig. 1. Each plate spring is composed of a root straight section, an oblique line section and an end straight section, the root straight section of each plate spring is equal in length, the oblique line section is unequal in length to the end straight section, namely, a half-symmetrical structural schematic diagram of a small number of oblique line type variable cross-section plate springs with unequal length is shown in figure 2, wherein each oblique line type variable cross-section plate spring 1, a root gasket 2, an end gasket 3 and a half length L of each plate spring are_TThe U clamping distance of the U is equal to half of the L clamping length of the plate spring_TU/4, half the clamping length L of the root flat section₂The number of the plate springs is n, n is more than or equal to 2 and less than or equal to 5, and the length L of the oblique line of each plate spring_xiThe length of the straight section at the end of each leaf spring is L_1iClamping length L of each leaf spring_ci＝L₂+L_xi+L_1iThe difference of half length of each plate spring is DeltaL_i＝L_ci-L_ci+1. The length from the root of the oblique line segment of each plate spring to the end point of the plate spring is L_2x＝L-L₂The length L from the end of the diagonal line segment of each leaf spring to the end point of the leaf spring_1xi＝L_2x-L_xi. The length from the root of the oblique line section of the end plate spring to the end point is L_xn+L_1nGreater than or equal to the length L of the diagonal segment of the first leaf spring_x1I.e. L_xn+L_1n>L_x1To increase the strength of the leaf spring ends. Thickness h of root straight section of each leaf spring_2iThickness h of the end straight section_1iThickness ratio of diagonal line segment beta_i＝h_1i/h_2iThe thickness h of the diagonal line segment at the x position is determined by taking the end point of the plate spring as the origin of coordinates_xi＝k_hix+C_hi，k_hiThe slope of the expression for the thickness of the inclined line segment of each leaf spring, C_hiIs a constant of the oblique line segment thickness expression, i is 1,2, …, n. Leaf spring width B, modulus of elasticity E. Delta_cThickness of root washer 2, delta_eIs a terminalThe thickness of the partial washer 3. The two ends of the cross section of each leaf spring are in the shapes of arc, chamfer and right angle, wherein the different types of cross sections can be uniformly used for chamfering the radius-thickness ratio k_rDenotes that 0. ltoreq. k_r1/2 is not more than r, k is 0_r0, the cross section is right-angled; when r is h/2, k_r1/2, the cross section is circular arc; when 0 is present<r<h/2，k_r1/2, the cross section is of a chamfer type, wherein each leaf spring is a schematic diagram of the shape of both ends of the cross section, as shown in fig. 3. Checking key parameters of clamping rigidity, suspension offset frequency, stress intensity, initial arc height and maximum limit of the plate spring according to design structure parameters, vehicle suspension parameters, allowable stress and maximum allowable stress under impact load of the given unequal-length few-piece oblique line type variable-section plate spring.

In order to solve the technical problem, the invention provides a method for checking key parameters of a non-isometric few-leaf diagonal variable-section leaf spring, which is characterized by adopting the following checking steps:

(1) equivalent width b of root straight section and end straight section of each leaf spring_2iAnd b_1iThe calculation of (2):

according to the width B of the plate spring, the types of two ends of the cross section and the thickness ratio k of the chamfer radius_r，0≤k_rNot more than 1/2, the number of the leaf springs is n, and the thickness h of the root straight section of each leaf spring_2iAnd the thickness h of the end straight section_1iFor the equivalent width b of the root straight section of each leaf spring_2iAnd equivalent width b of the end straight section_1iMake a calculation where i is 1,2, …, n, i.e.

b_2i＝B+D_brh_2i；b_1i＝B+D_brh_1i；

In the formula (I), the compound is shown in the specification,

is an equivalent width reduction coefficient, wherein k is more than or equal to 0_r≤1/2，-0.411≤D_br≤0。

(2) Clamping rigidity K of unequal-length few-leaf oblique-line-type variable-cross-section plate spring_CChecking:

step A:root straight section flexibility R of each plate spring_driIs calculated by

According to half length L of the plate spring_TThe U clamping distance of the U is equal to half of the L clamping length of the plate spring_TU/4, the number n of leaf springs, the length L from the root of the diagonal segment of each leaf spring to the leaf spring end point_2xThickness h of straight section of root_2iElastic modulus E, b calculated in step (1)_2iFor the root straight section flexibility R of each plate spring_driMake a calculation where i is 1,2, …, n, i.e.

And B, step: bias line segment flexibility R of each plate spring_dxiIs calculated by

According to the width B, the elastic modulus E, the number n of the leaf springs and the h of each leaf spring_2i，h_1i，L_XiThe thickness ratio beta of the oblique line segments of each leaf spring_i＝h_1i/h_2iLength L from end of oblique line segment of each leaf spring to end point of leaf spring_1xiConstant of expression of thickness of oblique line segment

D obtained by calculation in step (1)_br，b_2i，b_1iAnd the equivalent width ratio lambda of the oblique line segment of each leaf spring_bi＝b_1i/b_2iFlexibility R of each leaf spring in oblique line section_dxiMake a calculation where i is 1,2, …, n, i.e.

When the two ends of the cross section are right-angled, the radius-thickness ratio k of the chamfer is_r0, equivalent width reduction factor D_br＝0，b_2i＝b_1i＝B，λ_i＝b_1i/b_2i1, the oblique line segment flexibility R of each plate spring_dxiIs composed of

C, step C: r from root of end straight section of each leaf spring to end point section of end leaf spring_d1ciIs calculated by

H of each plate spring according to the number n of the plate springs_1i，L_1xiDifference DeltaL of half length of each plate spring_iElastic modulus E, b calculated in step (1)_1iFor R of the root of the end straight section of each leaf spring to the end point section of the last leaf spring_d1ciMake a calculation where i is 1,2, …, n, i.e.

D, step: compliance R of the overlapping section of the last leaf spring of a leaf spring_drxcIs calculated by

According to the number n of the plate springs, R calculated in the step A_driR calculated in step B_dxiR calculated in step C_d1ciCompliance R of the overlapping section of the last leaf spring of the leaf spring_drxcPerform calculations, i.e.

E, step E: compliance R of the overlapping section of the end of the leaf spring outside the last leaf spring_deIs calculated by

According to the number n of the leaf springs, the number n of the overlapped sections of the leaf spring end parts outside the last leaf spring_cThickness h of end straight section of front n-1 plate spring_1iDifference DeltaL of half length of each plate spring_iElastic modulus E, b calculated in step (1)_1iCompliance R of the overlapping section of the end of the leaf spring outside the last leaf spring_dePerform calculations, i.e.

And F, step: few-leaf oblique-line type plate spring clamping rigidity K_CChecking calculation of

According to the R calculated in the step D_drxcR calculated in step E_deClamping stiffness K to leaf spring_CPerforming check calculations, i.e.

(3) Checking the stress intensity of the unequal-length few-leaf oblique line type variable-section plate spring:

i, step: bending moment load sharing M of each plate spring_iIs calculated by

According to half length L of the plate spring_TU clamping distance of riding bolt and P rated load_NN number of leaf springs, R calculated in step (2) A_driR calculated in step B_dxiR calculated in step C_d1ciFor each plate spring, sharing bending moment load M_iMake a calculation where i is 1,2, …, n, i.e.

II, step (2): root maximum stress sigma of each leaf spring_maxiCalculation and intensity checking

According to the number n of the leaf springs, the root h of each leaf spring_2iAllowable stress [ sigma ] under rated load_N]B calculated in step (1)_2iM calculated in step I_iFor root maximum stress σ of each leaf spring_maxiPerform calculations, i.e.

Will sigma_maxiAnd [ sigma ]_N]Making a comparison if σ_maxi<[σ_N]The plate spring satisfies the stress strengthRequiring; otherwise, the leaf spring does not meet the stress strength requirements.

(4) Suspension offset frequency f of unequal-length few-leaf oblique line type variable-section plate spring₀Checking:

according to the rated load P_NChecking the calculated K in step (2)_CFor unequal length few-leaf oblique line type variable cross-section plate spring suspension offset frequency f₀Is checked, i.e.

F calculated from the check₀Design requirement value f of suspension offset frequency_0RMaking a comparison if f₀＝f_0RIf not, the suspension offset frequency does not meet the design requirement value.

(5) Initial arc height H of unequal-length few-leaf oblique line type variable-section plate spring_gCChecking:

according to the rated load P_NInitial arc height design value H_gCdesK obtained by checking in step (2)_CFor the initial arc height H of the unequal length few-leaf oblique line type variable cross-section plate spring_gCdesAnd residual arc height H under rated load_gsyIs checked, i.e.

H calculated by checking_gsyDesign requirement value H of residual arc height_gsyRMaking a comparison if H_gsy＝H_gsyRInitial arc height design value H_gCdesIs reasonable, otherwise, the initial arc height design value H_gCdesIs not reasonable.

(6) Maximum limit deflection f of non-isometric few-leaf oblique line type variable cross-section plate spring_maxXChecking:

i, step: maximum allowable load P under impact load_XIs calculated by

According to the maximum limit deflection design value f_maxXdesChecking the calculated K in step (2)_CMaximum allowable load P under impact load_XPerform calculations, i.e.

P_X＝K_Cf_maxXdes；

ii, step: maximum impact bending moment M shared by each leaf spring under maximum limit deflection_Xi

According to half length L of the plate spring_TU clamping distance of the horseback bolt, n number of leaf spring pieces, and R calculated in the step (2) A_driR calculated in step B_dxiR calculated in step C_d1ciP calculated in step i_XFor each plate spring, sharing bending moment load M_XiMake a calculation where i is 1,2, …, n, i.e.

And iii, step (ii): maximum limit deflection f_maxXRoot maximum impact stress sigma of lower leaf springs_XiAnd checking

H of each plate spring according to the number n of the plate springs_2iMaximum allowable stress [ sigma ] under impact load_X]B calculated in step (1)_2iIi M calculated in step_XiFor the maximum limit deflection design value f_maxXdesRoot maximum impact stress sigma of lower leaf springs_XiMake a calculation where i is 1,2, …, n, i.e.

Will calculate the obtained sigma_XiAnd [ sigma ]_X]Making a comparison if σ_Xi<[σ_X]Design value f of maximum limit deflection of plate spring_maxXdesThe design requirement of the impact stress strength is met; otherwise, the design value f of the maximum limit deflection of the plate spring_maxXdesThe design requirement of impact stress strength is not satisfied.

The invention has the advantages over the prior art

Because the lengths of the inclined line sections and the end parts of the unequal-length few-leaf oblique-line-type variable-section plate springs are unequal, and under the condition of considering the shapes of the two ends of the cross section and the influence on the rigidity, the rigidity calculation of the unequal-length few-leaf oblique-line-type variable-section plate springs and the calculation of the shared load of each leaf spring are very complicated, so that an accurate and reliable checking method for key parameters of the unequal-length few-leaf oblique-line-type variable-section plate springs has not been provided at home and abroad in the prior art. The method can check the clamping rigidity, the suspension offset frequency, the stress intensity, the initial tangent arc height and the maximum limit deflection of the unequal-length few-leaf oblique line type variable-section plate spring according to the design structure parameters, the elastic modulus, the rated load, the allowable stress under the rated load and the maximum allowable stress under the impact load of the given plate spring. As can be seen from the test of examples and prototype machines, the method for checking the key parameters of the variable-section plate spring with the non-equal length and few-leaf oblique lines is correct. The method is utilized to obtain accurate and reliable checking calculation values of key parameters of the unequal length diagonal variable cross-section plate spring, ensure that the key parameters of the clamping rigidity, the suspension offset frequency, the stress intensity, the initial arc height and the maximum limit deflection of the plate spring meet the design requirements of the plate spring and the suspension, and improve the design level of the plate spring and the driving smoothness and safety of a vehicle; meanwhile, the test cost of the product is reduced, and the product development speed is accelerated.

Drawings

For a better understanding of the present invention, reference is made to the following further description taken in conjunction with the accompanying drawings.

FIG. 1 is a flow chart for checking key parameters of a variable cross-section leaf spring with a plurality of unequal length pieces and a plurality of oblique lines;

FIG. 2 is a schematic view of a semi-symmetrical structure of a variable cross-section leaf spring with a plurality of oblique sheets of unequal length;

fig. 3 is a schematic diagram of the shapes of both ends of the cross section of a variable section plate spring of a non-equal length few-leaf oblique line type.

Detailed Description

The present invention will be described in further detail by way of examples.

The first embodiment is as follows: the width B of some unequal-length few-leaf oblique line type variable-section plate spring is known to be 70mm, and the elastic dieThe quantity E is 206GPa, the number n of plate springs is 3, and the half length L of the plate spring_T650mm, U100 mm, half L of the first leaf spring_T-U/4-625 mm, wherein the effective length L of the root flat section₂The length L from the root of each inclined line segment of each leaf spring to the end point of the leaf spring is 25mm_2x＝L-L₂600 mm. Root straight section thickness h of each plate spring_2iI.e. h₂₁＝16mm，h₂₂＝h₂₃15mm, the thickness h of the end straight section of each leaf spring_1iI.e. h₁₁＝10mm，h₁₂＝h₁₃9mm, the oblique line section thickness ratio beta of each plate spring₁＝0.625，β₂＝β₃0.6. Length L of straight end portion of each leaf spring_1iI.e. L₁₁＝220mm，L₁₂＝L₁₃110 mm. Length L of oblique line of each leaf spring_X1＝380mm，L_X2＝352.5mm，L_X3325mm, the length L from the end of each oblique line segment of the leaf spring to the end point of the leaf spring_1xi＝L_2x-L_XiI.e. L_1x1＝220mm，L_1x2＝247.5mm，L_1x3275.0 mm. Clamping length L of each leaf spring_ci＝L₂+L_Xi+L_1iI.e. L_c1＝625mm，L_c2＝487.5mm，L_c3460mm, half the length difference DeltaL of each leaf spring_i＝L_ci-L_ci+1I.e. Δ L₁＝137.5mm，ΔL₂27.5 mm. The two ends of the cross section of the plate spring are arc-shaped, namely the radius-thickness ratio k of the chamfer_r1/2. Rated load P of plate spring_N10651N, the design value requirement f of the suspension offset frequency_0R1.9Hz, initial arc height design value H_gCdes98.8mm, a design requirement value H of high residual arc of plate spring under rated load_gsyR30mm, allowable stress [ sigma ] of plate spring under rated load_N]Maximum allowable stress [ sigma ] under impact load at 500MPa_X]700MPa, design value f of maximum limit deflection_maxXdes99.7 mm. According to the design structure parameters, the elastic modulus, the rated load, the allowable stress under the rated load and the impact load of the given plate springAnd checking and calculating the clamping rigidity, the suspension offset frequency, the stress intensity, the initial tangent arc height and the maximum limiting deflection of the unequal-length few-leaf oblique-line-type variable-section plate spring to obtain the maximum allowable stress.

The checking method for the key parameters of the unequal-length few-leaf oblique line type variable-section leaf spring provided by the embodiment of the invention has the checking flow as shown in figure 1, and specifically comprises the following checking steps:

(1) equivalent width b of root straight section and end straight section_2iAnd b_1iThe calculation of (2):

according to the width B of the plate spring being 70mm, the number n of the plate springs being 3, the thickness h of the root straight section of each plate spring₂₁＝16mm，h₂₂＝h₂₃15mm, the thickness h of the end straight section of each leaf spring₁₁＝10mm，h₁₂＝h₁₃9mm, and the radius-thickness ratio k of the chamfer is arc-shaped at two ends of the cross section_r1/2, the equivalent width b of each flat section of the root of each leaf spring of the unequal few-leaf oblique line type variable cross-section leaf spring_2iEquivalent width b of straight end section_1iPerform calculations, i.e.

b_2i＝B+D_brh_2i；b_1i＝B+D_brh_1i；

In the formula (I), the compound is shown in the specification,

wherein, b₂₁＝63.4mm，b₂₂＝b₂₃＝63.8mm；b₁₁＝65.9mm，b₁₂＝b₁₃＝66.3mm；

(2) Unequal-length few-leaf oblique-line-type variable-cross-section plate spring clamping rigidity K_CChecking:

step A: root straight section flexibility R of each plate spring_driIs calculated by

Half the length L of the plate spring according to the number n of the plate springs being 3_T650mm, U100 mm, half L of the first leaf spring_T-625 mm, length L from root of oblique line segment to end point of leaf spring_2xH of each leaf spring being 600mm₂₁＝16mm，h₂₂＝h₂₃＝15mm，Elastic modulus E206 GPa, calculated in step (1)₂₁＝63.4mm，b₂₂＝b₂₃Flexibility R of root straight section of each plate spring is 63.8mm_driMake a calculation where i is 1,2, …, n, i.e.

Wherein R is_dr1＝1.052×10^-3mm/N，R_dr2＝R_dr3＝1.268×10^-3mm/N，

According to the width B of the plate spring being 70mm, the elastic modulus E being 206GPa, the number n of the plate springs being 3, h of each plate spring₂₁＝16mm，h₂₂＝h₂₃＝15mm；h₁₁＝10mm，h₁₂＝h₁₃＝9mm；L_2x600mmm, length L from end of oblique line segment of each leaf spring to end point of leaf spring_1x1＝220mm，L_1x2＝247.5mm，L_1x3275.0mm, length L of oblique line of each leaf spring_X1＝380mm，L_X2＝352.5mm，L_X3325 mm; constant of thickness expression of inclined line segment of each leaf spring

I.e. C_h1＝6.5mm，C_h2＝4.8mm，C_h33.9mm, the thickness ratio beta of the oblique line segments of each leaf spring₁＝0.625，β₂＝β₃D calculated in step (1) when equal to 0.6_br＝-0.411，b₂₁＝63.4mm，b₂₂＝b₂₃＝63.8mm；b₁₁＝65.9mm，b₁₂＝b₁₃66.3 mm; equivalent width ratio lambda of inclined line segment of each leaf spring_bi＝b_1i/b_2iI.e. λ_b1＝λ_b2＝λ_b3When the total number of leaf springs is 1.0386, i is 1,2, …, n, the flexibility of the oblique line section of each leaf spring is calculated, namely

Namely R_dx1＝1.264×10^-2mm/N，R_dx2＝1.597×10^-2mm/N，R_dx3＝1.586×10^-2mm/N；

C, step C: flexibility R of root of end straight section of each leaf spring to end point section of last leaf spring_d1ciIs calculated by

The spring modulus E is 206GPa, and h of each plate spring is calculated according to the number n of the plate springs to be 3 and the elastic modulus E to be 206GPa₁₁＝10mm，h₁₂＝h₁₃9mm, the difference DeltaL of half the length of each leaf spring₁＝137.5mm，ΔL₂L of each leaf spring of 27.5mm_1x1＝220mm，L_1x2＝247.5mm，L_1x3275mm, b calculated in step (1)₁₁＝65.9mm，b₁₂＝b₁₃66.3 mm; r for the root of the end straight section of each leaf spring to the end point section of the last leaf spring_d1ciMake a calculation where i is 1,2, …, n, i.e.

Wherein R is_d1c1＝0.907×10^-3mm/N，R_d1c2＝2.142×10^-3mm/N，R_d1c3＝3.274×10^-3mm/N，

According to the number n of the plate springs being 3, R calculated in the step A_dr1＝1.052×10^-3mm/N，R_dr2＝R_dr3＝1.268×10^-3mm/N, R calculated in step B_dx1＝1.264×10^-2mm/N，R_dx2＝1.597×10^-2mm/N，R_dx3＝1.586×10^-2R calculated in mm/N, C step_d1c1＝0.907×10^-3mm/N，R_d1c2＝2.142×10^-3mm/N，R_d1c3＝3.274×10^-3mm/N, for overlapping sections of the last leaf springs of the leaf springsCompliance R_drxcPerform calculations, i.e.

According to the number n of the leaf springs being 3, the number n of the leaf springs at the overlapping section of the leaf spring end outside the last leaf spring_cThe thickness h of the end straight section of the front 2 plate springs is equal to n-1 and 2₁₁＝10mm，h₁₂9mm, the difference DeltaL of half the length of each leaf spring₁＝137.5mm，ΔL₂27.5mm, modulus of elasticity E206 GPa, calculated in step (1)₁₁＝65.9mm，b₁₂Compliance R of the overlapping section of the end of the leaf spring outside the last leaf spring of 66.3mm_dePerform calculations, i.e.

And F, step: leaf spring clamping stiffness K_CChecking calculation of

According to the R calculated in the step D_drxc＝5.9142×10^-3mm/N, R calculated in step E_de＝5.4372×10^-4mm/N, clamping stiffness K for leaf spring_CPerforming check calculations, i.e.

i, step: bending moment load sharing M of each plate spring_iIs calculated by

According to half length L of the plate spring_T650mm, 100mm clamping distance U of riding bolt, and rated load P_N10651N, the number of leaf spring pieces N being 3, R calculated in step (2) a_dr1＝1.052×10^-3mm/N，R_dr2＝R_dr3＝1.268×10^-3mm/N, R calculated in step B_dx1＝1.264×10^-2mm/N，R_dx2＝1.597×10^-2mm/N，R_dx3＝1.586×10^-2R calculated in mm/N, C step_d1c1＝0.907×10^-3mm/N，R_d1c2＝2.142×10^-3mm/N，R_d1c3＝3.274×10^-3mm/N, bending moment load M shared by each plate spring_iMake a calculation where i is 1,2, …, n, i.e.

Wherein M is₁＝2.588×10³N.m，M₂＝1.9499×10³N.m，M₃＝1.8525×10³N.m。

H of each plate spring is 3 according to the number n of the plate springs₂₁＝16mm，h₂₂＝h₂₃Allowable stress [ sigma ] at rated load of 15mm_N]B calculated in step (1) at 500MPa₂₁＝63.4mm，b₂₂＝b₂₃M calculated in step I, 63.8mm₁＝2.588×10³N.m，M₂＝1.9499×10³N.m，M₃＝1.8525×10³N.m. root maximum stress σ to each leaf spring_maxiPerform calculations, i.e.

Wherein σ_max1＝478.18MPa，σ_max2＝407.28MPa，σ_max3＝386.92MPa，

As can be seen, σ_maxi<[σ_N]And the plate spring meets the design requirement of stress strength.

(4) Unequal length few-leaf oblique line type variable cross-section plate spring suspension offset frequency f₀Checking:

according to the rated load P_NChecking the calculated K in step (2) 10651N_CChecking the bias frequency of the variable cross-section plate spring suspension with unequal length and few inclined pieces when the suspension is 154.89N/mm, namely

Checking the value f of the suspension offset frequency₀And the design requirement value f_0RBy contrast, it can be seen that f₀＝f_0RThe bias frequency of the variable cross-section plate spring suspension with the unequal length and few pieces of oblique lines meets the design requirement value because the bias frequency of the variable cross-section plate spring suspension with the unequal length and few pieces of oblique lines is 1.9 Hz.

according to the rated load P_N10651N, initial arc height set value H_gCdesChecking the obtained K in step (2) at 98.8mm_CThe initial arc height design value H of the unequal length few-leaf oblique line type variable cross-section plate spring is 154.89N/mm_gCdesAnd residual arc height H under rated load_gsyIs checked, i.e.

H calculated by checking_gsy30mm and the design requirement value H_gsyRWhen the thickness of the film was compared with 30mm, H was found_gsy＝H_gsyRTherefore, the design value of the initial arc height of the plate spring is reasonable, and the design requirement value of the residual arc height under the rated load is met.

i, step: maximum allowable load P under impact load_XIs calculated by

According to the maximum limit deflection design value f_maxXdesChecking the calculated K in step (2) at 99.7mm_C154.89N/mm, maximum allowable load P under impact load_XIs checked, i.e.

P_X＝K_Cf_maxXdes＝15436N。

Half the length L of the plate spring according to the number n of the plate springs being 3_T650mm, and 100mm as the U clamping distance of the saddle bolt, and R calculated in step (2) a_dr1＝1.052×10^-3mm/N，R_dr2＝R_dr3＝1.268×10^-3mm/N, R calculated in step B_dx1＝1.264×10^-2mm/N，R_dx2＝1.597×10^-2mm/N，R_dx3＝1.586×10^-2R calculated in mm/N, C step_d1c1＝0.907×10^-3mm/N，R_d1c2＝2.142×10^-3mm/N，R_d1c3＝3.274×10^-3P calculated in mm/N, i step_X15436N, the moment load M is shared by the leaf springs_XiMake a calculation where i is 1,2, …, n, i.e.

Wherein M is_X1＝3.7509×10³N.m，M_X2＝2.8261×10³N.m，M_X3＝2.6848×10³N.m。

And iii, step (ii): maximum limit deflection design value f_maxXdesRoot maximum impact stress sigma of lower leaf springs_XiAnd checking

H of each plate spring is 3 according to the number n of the plate springs₂₁＝16mm，h₂₂＝h₂₃Maximum allowable stress [ sigma ] under impact load of 15mm_X]700MPa, b calculated in step (1)₂₁＝63.4mm，b₂₂＝b₂₃M calculated in step ii of 63.8mm_X1＝3.7509×10³N.m，M_X2＝2.8261×10³N.m，M_X3＝2.6848×10³N.m. design value f for maximum limit deflection_maxXdesRoot maximum impact stress sigma of lower leaf springs_XiMake a calculation where i is 1,2, …, n, i.e.

Wherein σ_X1＝693.05MPa，σ_X2＝590.28MPa，σ_X3＝560.78MPa，

It can be seen that the maximum limit deflection design value f_maxXdesRoot maximum impact stress sigma of lower leaf springs_Xi<[σ_X]Therefore, the design value of the maximum limit deflection of the plate spring is reasonable, and the maximum allowable stress [ sigma ] under the impact load is satisfied_X]The design requirements of (2).

Example two: the known variable-section plate spring with a few inclined pieces of unequal length has the same structural parameters as those of the first embodiment except for the shapes of two ends of the cross section, the rated load, the initial arc height and the maximum limit deflection. Wherein, both ends of the cross section of the plate spring are chamfer-shaped, and the radius-thickness ratio k of the chamfer is_r1/4. Rated load P of plate spring_N11217N, design value f of maximum limit deflection_maxXdes101.0 mm. And checking and calculating the clamping rigidity, the suspension offset frequency, the stress intensity, the initial tangent arc height and the maximum limit deflection of the unequal-length few-leaf oblique line type variable-section plate spring according to the design structure parameters, the elastic modulus, the rated load, the allowable stress under the rated load and the maximum allowable stress under the impact load of the given plate spring.

The embodiment of the invention adopts the checking step of the first embodiment to check the unequal length few-leaf diagonal variable section plate spring, and the specific checking step is as follows:

according to the width B of the plate spring being 70mm, the chamfer radius thickness ratio k at the two ends of the cross section_r1/4, the number n of the leaf springs is 3, and the thickness h of the root straight section of each leaf spring₂₁＝16mm，h₂₂＝h₂₃15mm, the ends of each leaf spring are straightSection thickness h₁₁＝10mm，h₁₂＝h₁₃Equal to 9mm, equal width b of each flat section of root of each leaf spring of unequal few-leaf oblique line type variable cross-section leaf spring_2iEquivalent width b of straight end section_1iPerform calculations, i.e.

b_2i＝B+D_brh_2i；b_1i＝B+D_brh_1i；

In the formula (I), the compound is shown in the specification,

wherein, b₂₁＝67.9mm，b₂₂＝b₂₃＝68.1mm；b₁₁＝68.7mm，b₁₂＝b₁₃＝68.8mm；

According to half length L of the plate spring_T650mm, U100 mm, and L, half of the leaf spring_T-U/4-625 mm, E-206 GPa, n-3 leaf springs, h of each leaf spring₂₁＝16mm，h₂₂＝h₂₃15mm, length L from the root of the oblique line section to the end point of the plate spring_2xB calculated in step (1) at 600mm₂₁＝67.9mm，b₂₂＝b₂₃Flexibility R of root straight section of each plate spring is 68.1mm_driMake a calculation where i is 1,2, …, n, i.e.

Wherein R is_dr1＝0.982×10^-3mm/N，R_dr2＝R_dr3＝1.189×10^-3mm/N，

According to the width B of the plate spring being 70mm, the elastic modulus E being 206GPa, the number n of the plate springs being 3, h of each plate spring₂₁＝16mm，h₂₂＝h₂₃＝15mm；h₁₁＝10mm，h₁₂＝h₁₃9 mm; the length L from the root of the oblique line section of each plate spring to the plate spring_2x600mmm, L from the end of each leaf spring oblique line segment to the leaf spring end point_1x1＝220mm，L_1x2＝247.5mm，L_1x3275.0 mm; length L of oblique line of each leaf spring_X1＝380mm，L_X2＝352.5mm，L_X3325 mm. Constant of thickness expression of inclined line segment of each leaf spring

I.e. C_h1＝6.5mm，C_h2＝4.8mm，C_h33.9mm, the thickness ratio beta of the oblique line segments of each leaf spring₁＝0.625，β₂＝β₃D calculated in step (1) when equal to 0.6_br＝-0.1284，b₂₁＝67.9mm，b₂₂＝b₂₃＝68.1mm；b₁₁＝68.7mm，b₁₂＝b₁₃68.8mm, the equivalent width ratio lambda of each leaf spring oblique line segment_b1＝λ_b2＝λ_b3When the total number of leaf springs is 1.0113, i is 1,2, …, n, the flexibility of the oblique line section of each leaf spring is calculated, namely

Namely R_dx1＝1.195×10^-2mm/N，R_dx2＝1.517×10^-2mm/N，R_dx3＝1.507×10^-2mm/N；

C, step C: r from root of end straight section of each leaf spring to end point section of last leaf spring_d1ciIs calculated by

The spring modulus E is 206GPa, and h of each plate spring is calculated according to the number n of the plate springs to be 3 and the elastic modulus E to be 206GPa₁₁＝10mm，h₁₂＝h₁₃9mm, the difference DeltaL of half the length of each leaf spring₁＝137.5mm，ΔL₂L of each leaf spring of 27.5mm_1x1＝220mm，L_1x2＝247.5mm，L_1x3275mm, b calculated in step (1)₁₁＝68.7mm，b₁₂＝b₁₃68.8 mm; r for the root of the end straight section of each leaf spring to the end point section of the last leaf spring_d1ciMake a calculation where i is 1,2, …, n, i.e.

Wherein R is_d1c1＝0.869×10^-3mm/N，R_d1c2＝2.063×10^-3mm/N，R_d1c3＝3.153×10^-3mm/N，

According to the number n of the plate springs being 3, R calculated in the step A_dr1＝0.982×10^-3mm/N，R_dr2＝R_dr3＝1.189×10^-3mm/N, R calculated in step B_dx1＝1.195×10^-2mm/N，R_dx2＝1.517×10^-2mm/N，R_dx3＝1.507×10^-2R calculated in mm/N, C step_d1c1＝0.869×10^-3mm/N，R_d1c2＝2.063×10^-3mm/N，R_d1c3＝3.153×10^-3mm/N, flexibility R of overlapping section of last leaf spring of leaf spring_drxcPerform calculations, i.e.

According to the number n of the plate springs being 3, the elastic modulus E being 206GPa, the number n of the overlapped sections of the end parts of the plate spring outside the last plate spring_cThe thickness h of the end straight section of the front 2 plate springs is equal to n-1 and 2₁₁＝10mm，h₁₂9mm, the difference DeltaL of half the length of each leaf spring₁＝137.5mm，ΔL₂B calculated in step (1) 27.5mm₁₁＝68.7mm，b₁₂68.8mm, and the end part of the plate spring outside the last plate spring is weightedCompliance R of the stack_dePerform calculations, i.e.

And F, step: leaf spring clamping stiffness K_CChecking calculation of

According to the R calculated in the step E_drxc＝5.6106×10^-3R calculated in mm/N, F step_de＝5.2165×10^-4mm/N, clamping stiffness K for leaf spring_CPerforming check calculations, i.e.

i, step: bending moment load sharing M of each plate spring_iIs calculated by

Half the length L of the plate spring according to the number n of the plate springs being 3_T650mm, 100mm clamping distance U of the saddle bolt, and rated load P of the plate spring_N11217N, R calculated in step (2) a_dr1＝0.982×10^-3mm/N，R_dr2＝R_dr3＝1.189×10^-3mm/N, R calculated in step B_dx1＝1.195×10^-2mm/N，R_dx2＝1.517×10^-2mm/N，R_dx3＝1.507×10^-2R calculated in mm/N, C step_d1c1＝0.869×10^-3mm/N，R_d1c2＝2.063×10^-3mm/N，R_d1c3＝3.153×10^-3mm/N, bending moment load M shared by each plate spring_iMake a calculation where i is 1,2, …, n, i.e.

Wherein M is₁＝2.7358×10³N.m，M₂＝2.0493×10³N.m，M₃＝1.9448×10³N.m。

H of each plate spring is 3 according to the number n of the plate springs₂₁＝16mm，h₂₂＝h₂₃15mm, allowable stress [ sigma ]_N]B calculated in step (1) at 500MPa₂₁＝67.9mm，b₂₂＝b₂₃M calculated in step I, 68.1mm₁＝2.7358×10³N.m，M₂＝2.0493×10³N.m，M₃＝1.9448×10³N.m. root maximum stress σ to each leaf spring_maxiMake a calculation where i is 1,2, …, n, i.e.

Wherein σ_max1＝471.86MPa，σ_max2＝401.39MPa，σ_max3＝380.92MPa，

As can be seen, σ_maxi<[σ_N]The leaf spring meets the stress strength requirements under rated load.

according to the rated load P_N11217N, checking the calculated K in step (2)_C163.12N/mm, offset frequency f for unequal length small piece oblique line type variable cross section plate spring suspension₀Is checked, i.e.

Checking the value f of the suspension offset frequency₀Design requirement value f of suspension offset frequency_0RBy comparison, it is found that f₀＝f_0RThe bias frequency of the variable cross-section plate spring suspension with unequal length and few inclined sheets meets the design requirement value because the bias frequency of the variable cross-section plate spring suspension with unequal length and few inclined sheets is 1.9 Hz.

according to the rated load P_N11217N, initial arc height design value H_gCdesChecking the obtained K in step (2) at 98.8mm_C163.12N/mm, initial arc height H for unequal length small piece oblique line type variable section plate spring_gCdesAnd residual arc height H under rated load_gsyIs checked, i.e.

Checking the calculated value H of the residual arc height_gsyAnd the design requirement value H_gsyRBy comparison, H is known_gsy＝H_gsyRThe initial arc height design value of the unequal length few-leaf oblique line type variable cross-section plate spring is reasonable and meets the design requirement of the residual arc height under the rated load.

i, step: maximum allowable load P under impact load_XIs calculated by

According to the maximum limit deflection design value f_maxXdesChecking the calculated K in step (2) at 101.0mm_C163.12N/mm, maximum allowable load P under impact load_XIs checked, i.e.

P_X＝K_Cf_maxXdes＝16477N。

Half the length L of the plate spring according to the number n of the plate springs being 3_T650mm, and 100mm as the U clamping distance of the saddle bolt, and R calculated in step (2) a_dr1＝0.982×10^-3mm/N，R_dr2＝R_dr3＝1.189×10^-3mm/N, R calculated in step B_dx1＝1.195×10^-2mm/N，R_dx2＝1.517×10^-2mm/N，R_dx3＝1.507×10^-2R calculated in mm/N, C step_d1c1＝0.869×10^-3mm/N，R_d1c2＝2.063×10^-3mm/N，R_d1c3＝3.153×10^-3P calculated in mm/N, i step_X16477N, the bending moment load M is shared by each plate spring_XiMake a calculation where i is 1,2, …, n, i.e.

Wherein M is_X1＝4.0188×10³N.m，M_X2＝3.0103×10³N.m，M_X3＝2.8586×10³N.m。

H of each plate spring is 3 according to the number n of the plate springs₂₁＝16mm，h₂₂＝h₂₃15mm, maximum allowable stress [ sigma ] under impact load_X]700MPa, b calculated in step (1)₂₁＝67.9mm，b₂₂＝b₂₃68.1mm, M calculated in step ii_X1＝4.0188×10³N.m，M_X2＝3.0103×10³N.m，M_X3＝2.8586×10³N.m, design value f for maximum limiting deflection_maxXdesRoot maximum impact stress sigma of lower leaf springs_XiMake a calculation where i is 1,2, …, n, i.e.

Wherein σ_X1＝693.14MPa，σ_X2＝589.62MPa，σ_X3＝559.55MPa，

It can be seen that the maximum limit deflection design value f_maxXdesRoot maximum impact stress sigma of lower leaf springs_Xi<[σ_X]Therefore, the design value of the maximum limit deflection of the plate spring is reasonable, and the maximum allowable stress [ sigma ] under the impact load is met_X]The design requirements of (2).

Example three: the known variable-section plate spring with a few inclined pieces of unequal length has the same structural parameters as those of the first embodiment except for the shapes of two ends of the cross section, the rated load, the initial arc height and the maximum limit deflection. Wherein, the two ends of the cross section of the plate spring are right-angled, and the radius-thickness ratio k of the chamfer angle_r0; rated load P of plate spring_N11473N, design initial arc height H of plate spring_gCdes98.8mm, design value f of maximum limit deflection_maxXdes101.6 mm. And checking and calculating the clamping rigidity, the suspension offset frequency, the stress intensity, the initial tangent arc height and the maximum limit deflection of the unequal-length few-leaf oblique line type variable-section plate spring according to the design structure parameters, the elastic modulus, the rated load, the allowable stress under the rated load and the maximum allowable stress under the impact load of the given plate spring.

The embodiment of the invention adopts the checking step of the first embodiment to check the unequal-length few-leaf diagonal variable-section plate spring, and the specific checking step comprises the following steps:

(1) equivalent width b of root straight section and end straight section_2iAnd b_1iIs calculated by

According to the width B of the plate spring being 70mm, the number n of the plate spring being 3, and the two ends of the cross section being right-angled, namely the chamfer radius thickness ratio k_r0, so that the root of each leaf spring has the equivalent width b of the straight section_2iEquivalent width b of straight end section_1iAre all equal to the leaf spring width B, i.e.

b_2i＝B；b_1i＝B，

Wherein, b₂₁＝b₂₂＝b₂₃＝70mm；b₁₁＝b₁₂＝b₁₃＝70mm；

According to half length L of the plate spring_T650mm, U100 mm, and L, half of the leaf spring_T-U/4-625 mm, modulus of elasticity E-206 GPa, number of leaf springs n-3, eachLength L from oblique line section root of leaf spring to leaf spring end point_2x600mm, root straight section thickness h of each leaf spring₂₁＝16mm，h₂₂＝h₂₃B calculated in step (1) 15mm₂₁＝b₂₂＝b₂₃70mm, and the compliance R of the root straight section of each plate spring_driMake a calculation where i is 1,2, …, n, i.e.

Wherein R is_dr1＝0.953×10^-3mm/N，R_dr2＝R_dr3＝1.156×10^-3mm/N，

According to the width B of the plate spring being 70mm, the cross section is right-angled, i.e. the chamfer radius thickness ratio k_r0, 206GPa, 3 and h for each plate spring₂₁＝16mm，h₂₂＝h₂₃＝15mm；h₁₁＝10mm，h₁₂＝h₁₃9 mm; length L of oblique line of each leaf spring_X1＝380mm，L_X2＝352.5mm，L_X3325 mm; the length L from the root of the oblique line section of each plate spring to the plate spring_2x600mmm, length L from end of oblique line segment of each leaf spring to end point of leaf spring_1x1＝220mm，L_1x2＝247.5mm，L_1x3275.0mm, constant C of thickness expression of oblique line segment of each leaf spring_h1＝6.5mm，C_h2＝4.8mm，C_h33.9mm, the thickness ratio beta of the oblique line segments of each leaf spring₁＝0.625，β₂＝β₃The oblique line segment flexibility of each leaf spring is calculated as 0.6, i is 1,2, …, n, that is

Namely R_dx1＝1.166×10^-2mm/N，R_dx2＝1.484×10^-2mm/N，R_dx3＝1.474×10^-2mm/N，

The spring modulus E is 206GPa, and h of each plate spring is calculated according to the number n of the plate springs to be 3 and the elastic modulus E to be 206GPa₁₁＝10mm，h₁₂＝h₁₃9mm, the difference DeltaL of half the length of each leaf spring₁＝137.5mm，ΔL₂L of each leaf spring of 27.5mm_1x1＝220mm，L_1x2＝247.5mm，L_1x3275mm, b calculated in step (1)₁₁＝b₁₂＝b₁₃70 mm; b, calculating R of the root part of the end straight section of each plate spring to the end point partial section of the last plate spring obtained in the step B_d1ciMake a calculation where i is 1,2, …, n, i.e.

Wherein R is_d1c1＝0.854×10^-3mm/N，R_d1c2＝2.029×10^-3mm/N，R_d1c3＝3.101×10^-3mm/N，

According to the number n of the plate springs being 3, R calculated in the step A_dr1＝0.953×10^-3mm/N，R_dr2＝R_dr3＝1.156×10^-3mm/N, R calculated in step B_dx1＝1.166×10^-2mm/N，R_dx2＝1.484×10^-2mm/N，R_dx3＝1.474×10^-2R calculated in mm/N, C step_d1c1＝0.854×10^-3mm/N，R_d1c2＝2.029×10^-3mm/N，R_d1c3＝3.101×10^-3mm/N, flexibility R of overlapping section of last leaf spring of leaf spring_drxcPerform calculations, i.e.

According to the number n of the leaf springs being 3, the number n of the leaf springs at the overlapping section of the leaf spring end outside the last leaf spring_cThe thickness h of the end straight section of the front 2 plate springs is equal to n-1 and 2₁₁＝10mm，h₁₂9mm, the difference DeltaL of half the length of each leaf spring₁＝137.5mm，ΔL₂27.5mm, modulus of elasticity E206 GPa, calculated in step (1)₁₁＝b₁₂Compliance R of 70mm to the overlapping section of the end of the leaf spring outside the last leaf spring_dePerform calculations, i.e.

And F, step: leaf spring clamping stiffness K_CChecking calculation of

According to the R calculated in the step D_drxc＝5.4828×10^-3mm/N, R calculated in step E_de＝5.1219×10^-4mm/N, clamping stiffness K for leaf spring_CPerforming check calculations, i.e.

i, step: bending moment load sharing M of each plate spring_iIs calculated by

Half the length L of the plate spring according to the number n of the plate springs being 3_T650mm, 100mm clamping distance U of riding bolt, and rated load P_NR calculated in step (2) a when 11473N is satisfied_dr1＝0.953×10^-3mm/N，R_dr2＝R_dr3＝1.156×10^-3mm/N, R calculated in step B_dx1＝1.166×10^-2mm/N，R_dx2＝1.484×10^-2mm/N，R_dx3＝1.474×10^-2mm/N, C in stepCalculated R_d1c1＝0.854×10^-3mm/N，R_d1c2＝2.029×10^-3mm/N，R_d1c3＝3.101×10^-3mm/N, bending moment load M shared by each plate spring_iMake a calculation where i is 1,2, …, n, i.e.

Wherein M is₁＝2.8029×10³N.m，M₂＝2.0944×10³N.m，M₃＝1.9867×10³N.m。

H of each plate spring is 3 according to the number n of the plate springs₂₁＝16mm，h₂₂＝h₂₃15mm, allowable stress [ sigma ]_N]B calculated in step (1) at 500MPa₂₁＝b₂₂＝b₂₃70mm, M calculated in step I₁＝2.8029×10³N.m，M₂＝2.0944×10³N.m，M₃＝1.9867×10³N.m. root maximum stress σ to each leaf spring_maxiMake a calculation where i is 1,2, …, n, i.e.

Wherein σ_max1＝469.23MPa，σ_max2＝398.93MPa，σ_max3＝378.42MPa，

As can be seen, σ_maxi<[σ_N]The leaf spring meets the design requirements for stress strength under rated load.

according to the rated load P_NChecking the calculated K in step (2) 11473N_C166.85N/mm, offset frequency f for unequal length small piece oblique line type variable cross section plate spring suspension₀Check is carried outIs calculated, i.e.

Is known as f₀＝f_0RThe suspension offset frequency of the unequal length few-leaf oblique line type variable cross-section plate spring meets the design requirement value when the suspension offset frequency is 1.9 Hz.

according to the rated load P_N11473N, residual arc height design requirement H under rated load_gsyR30mm, design value H of initial arc height_gCdesChecking the obtained K in step (2) at 98.8mm_C166.85N/mm, initial arc height H for unequal length small piece oblique line type variable section plate spring_gCAnd residual arc height H under rated load_gsyIs checked, i.e.

Can know H_gsy＝H_gsyR30mm, therefore, the design value of the initial arc height of the plate spring is reasonable, and the design requirement of the residual arc height under the rated load is met.

i, step: maximum allowable load P under impact load_XIs calculated by

According to the maximum limit deflection design value f_maxXdesChecking the calculated K in step (2) at 101.6mm_C166.85N/mm, maximum allowable load P under impact load_XIs checked, i.e.

P_X＝K_Cf_maxXdes＝16949N。

Half the length L of the plate spring according to the number n of the plate springs being 3_T650mm, and 100mm as the U clamping distance of the saddle bolt, and R calculated in step (2) a_dr1＝0.953×10^-3mm/N，R_dr2＝R_dr3＝1.156×10^-3mm/N, R calculated in step B_dx1＝1.166×10^-2mm/N，R_dx2＝1.484×10^-2mm/N，R_dx3＝1.474×10^-2R calculated in mm/N, C step_d1c1＝0.854×10^-3mm/N，R_d1c2＝2.029×10^-3mm/N，R_d1c3＝3.101×10^-3P calculated in mm/N, i step_X16949N, bending moment load M is shared by each plate spring_XiMake a calculation where i is 1,2, …, n, i.e.

Wherein M is_X1＝4.1406×10³N.m，M_X2＝3.0939×10³N.m，M_X3＝2.9348×10³N.m。

H of each plate spring is 3 according to the number n of the plate springs₂₁＝16mm，h₂₂＝h₂₃15mm, maximum allowable stress [ sigma ] under impact load_X]700MPa, b calculated in step (1)₂₁＝b₂₂＝b₂₃70mm, M calculated in step ii_X1＝4.1406×10³N.m，M_X2＝3.0939×10³N.m，M_X3＝2.9348×10³N.m, design value f for maximum limiting deflection_maxXdesRoot maximum impact stress sigma of lower leaf springs_XiMake a calculation where i is 1,2, …, n, i.e.

Wherein σ_X1＝693.18MPa，σ_X2＝589.31MPa，σ_X3＝559.01MPa。

It can be seen that the maximum limit deflection design value f_maxXdesRoot maximum impact stress sigma of each leaf spring below_Xi<[σ_X]Therefore, the design value f of the maximum limit deflection of the plate spring_maxXdesIs reasonable and meets the maximum allowable stress [ sigma ] under the impact load_X]The design requirements of (2).

According to the plate spring prototype test, the method for checking the key parameters of the unequal length few-leaf oblique line type variable cross-section plate spring is correct, and a reliable technical method is provided for checking the clamping rigidity, the suspension offset frequency, the initial arc height, the stress intensity and the maximum limit deflection of the unequal length oblique line type variable cross-section plate spring. By utilizing the method, the key parameters and strength of the unequal length diagonal variable cross-section plate spring with given design structure parameters can be checked, the clamping rigidity, suspension offset frequency, stress strength and initial arc height of the plate spring and the maximum limit deflection of the plate spring are ensured to meet the design requirements of the plate spring and the suspension, and the design level and performance of the plate spring and the driving smoothness and safety of a vehicle are improved; meanwhile, the test cost of the product is reduced, and the product development speed is accelerated.

Claims

1. A method for checking key parameters of a variable cross-section plate spring with a plurality of unequal length oblique lines is disclosed, wherein each plate spring is composed of a root straight section, an oblique line section and an end straight section, and the lengths of the end straight sections of the plate springs are unequal, namely the variable cross-section plate spring with the unequal length oblique lines is formed; checking the clamping rigidity, the suspension offset frequency, the stress intensity, the initial tangent arc height and the maximum limit deflection of a few-leaf oblique line type variable-section plate spring with unequal length according to the design structure parameters, the elastic modulus, the rated load, the allowable stress under the rated load and the maximum allowable stress under the impact load of the given plate spring; the method is characterized by comprising the following checking steps:

(2) unequal length less piece oblique line type section changingClamping stiffness K of leaf spring_CChecking:

(3) checking the stress intensity of the unequal-length few-leaf oblique line type variable-section plate spring;

(4) checking the offset frequency of the unequal-length few-leaf oblique line type variable-section plate spring suspension;

(6) maximum limit deflection f of non-isometric few-leaf oblique line type variable cross-section plate spring_maxXAnd (4) checking.

2. The clamping rigidity K of the variable cross-section leaf spring of the unequal length few leaf diagonal type according to the step (2) of claim 1_CThe checking method is characterized by comprising the following checking steps:

D calculated in step (1) of claim 1_br，b_2i，b_1iAnd the equivalent width ratio lambda of the oblique line segment of each leaf spring_bi＝b_1i/b_2iFlexibility R of each leaf spring in oblique line section_dxiMake a calculation where i is 1,2, …, n, i.e.

The difference DeltaL of half length of each plate spring is determined according to the number n of plate springs_i，h_1i，L_1xiElastic modulus E, b calculated in step (1) of claim 1_1iFor R of the root of the end straight section of each leaf spring to the end point section of the last leaf spring_d1ciMake a calculation where i is 1,2, …, n, i.e.

According to the number n of the plate springs, R calculated in the step A_driR calculated in step B_dxiR calculated in step C_d1ciCompliance R of the overlapping section of the last leaf spring of the leaf spring_drxcPerform calculationI.e. by

According to the number n of the leaf springs, the number n of the overlapped sections of the leaf spring end parts outside the last leaf spring_cThickness h of end straight section of front n-1 plate spring_1iDifference DeltaL of half length of each plate spring_iElastic modulus E, b calculated in the step (1) of claim 1_1iCompliance R of the overlapping section of the end of the leaf spring outside the last leaf spring_dePerform calculations, i.e.

3. The checking of the stress intensity of the unequal length few-leaf diagonal variable section plate spring according to the step (3) of claim 1, wherein:

i, step: bending moment load sharing M of each plate spring_iIs calculated by

According to half length L of the plate spring_TU clamping distance of riding bolt and P rated load_NN, the number of leaf springs, R calculated in step A of claim 2_driR calculated in step B_dxiR calculated in step C_d1ciFor each leaf springSharing bending moment load M_iMake a calculation where i is 1,2, …, n, i.e.

H of each plate spring according to the number n of the plate springs_2iAllowable stress [ sigma ] under rated load_N]B calculated in step (1) of claim 1_2iM calculated in step I_iFor root maximum stress σ of each leaf spring_maxiPerform calculations, i.e.

Will sigma_maxiAnd [ sigma ]_N]Making a comparison if σ_maxi<[σ_N]The plate spring meets the requirement of stress strength; otherwise, the leaf spring does not meet the stress strength requirements.

4. The checking of the maximum limit deflection of the unequal length few-leaf diagonal variable section leaf spring according to the step (6) of claim 1, wherein:

i, step: maximum allowable load P under impact load_XIs calculated by

According to the maximum limit deflection design value f_maxXdesThe method of claim 2 wherein the calculated K is checked_CMaximum allowable load P under impact load_XPerform calculations, i.e.

P_X＝K_Cf_maxXdes；

According to half length L of the plate spring_TU, n, R, calculated in step A of claim 2_driIn step BCalculated R_dxiR calculated in step C_d1ciP calculated in step i_XFor each plate spring, sharing bending moment load M_XiMake a calculation where i is 1,2, …, n, i.e.

H of each plate spring according to the number n of the plate springs_2iMaximum allowable stress [ sigma ] under impact load_X]B calculated in step (1) of claim 1_2iIi M calculated in step_XiFor the maximum limit deflection design value f_maxXdesRoot maximum impact stress sigma of lower leaf springs_XiMake a calculation where i is 1,2, …, n, i.e.