CN104156547A - Method for designing optimal damping characteristics of shock absorber of vehicle steel plate spring suspension system - Google Patents

Abstract

The invention relates to a design method for optimal damping characteristics of a shock absorber in a vehicle leaf spring suspension system, which belongs to the technical field of vehicle leaf spring suspension, and is characterized in that: according to the parameters of the vehicle suspension system, the optimal damping required by the suspension system is determined. According to the displacement and load measured by the leaf spring loading and unloading deformation test, the damping ratio of the leaf spring suspension system itself is calculated and analyzed; on this basis, the vibration reduction of the vehicle leaf spring suspension system The best damping characteristics of the device are designed. Through the Matlab/simulink simulation verification, it can be seen that the best damping characteristic design value of the leaf spring suspension system shock absorber can be designed by using the present invention, so that the vehicle leaf spring suspension system can reach the best damping matching, and the ride comfort of the vehicle can be improved; At the same time, repeated tests and verifications can be avoided, product development speed can be accelerated, and design and test costs can be reduced.

Description

Design Method for Optimum Damping Characteristics of Shock Absorber in Vehicle Leaf Spring Suspension System

technical field

The invention relates to a vehicle leaf spring suspension system, in particular to a design method for optimum damping characteristics of a shock absorber of the vehicle leaf spring suspension system.

Background technique

For many trucks, leaf spring suspension systems are mostly used. Although the leaf spring has a certain damping effect, it is difficult to achieve the best damping matching for the vehicle suspension by relying on the leaf spring alone, which cannot meet the requirements of vehicle ride comfort and safety. Require. With the rapid development of the vehicle industry and the continuous increase of vehicle speed, higher design requirements are put forward for the design of the leaf spring suspension system of trucks. Therefore, it is necessary to add hydraulic shock absorbers to the vehicle leaf spring suspension system. However, at present, no reliable design method has been given for adding hydraulic shock absorbers to the leaf spring suspension system. Usually, according to the type of vehicle, a certain shock absorber is selected based on experience, and then loaded into the vehicle and passed the ride comfort test of the vehicle. The vehicle's leaf spring suspension system is matched with shock absorbers. At present, the traditional design method of the shock absorber of the vehicle leaf spring suspension system cannot meet the design requirements of vehicle development and vehicle ride comfort, and the design cycle is long, and the test and design costs are high. Therefore, it is necessary to establish an accurate and reliable design method for the optimal damping characteristics of the shock absorber of the vehicle leaf spring suspension system, that is, according to the damping ratio of the leaf spring suspension system itself, through the requirements of the vehicle suspension system The optimal damping ratio is to design the optimal damping of the shock absorber required by the vehicle leaf spring suspension system, so as to improve the ride comfort of the vehicle and reduce the design and test costs.

Contents of the invention

In view of the above-mentioned defects in the prior art, the technical problem to be solved by the present invention is to provide an accurate and reliable design method for the optimum damping characteristics of the shock absorber of the vehicle leaf spring suspension system, the design process of which is shown in Figure 1 .

In order to solve the above-mentioned technical problems, the method for designing the best damping characteristics of the shock absorber of the vehicle leaf spring suspension system provided by the present invention, its technical solution implementation steps are as follows:

(1) Determine the optimal damping ratio ξ _o required by the vehicle suspension system:

According to the vehicle parameters, determine the optimal damping ratio ξ _o required by the vehicle leaf spring suspension system. The specific steps are as follows:

Step A: Determine the optimal damping ratio ξ _oc of the vehicle suspension system based on comfort:

According to the sprung mass m ₂ of the vehicle's single-wheel suspension, the suspension stiffness k ₂ , the unsprung mass m ₁ , and the tire stiffness k _t , the optimal damping ratio ξ _oc of the vehicle suspension system based on comfort is determined, namely:

${\mathrm{<span\; class="notranslate">\; \&xi;</span>}}_{\mathrm{<span\; class="notranslate">\; oc</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}\sqrt{\frac{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}}{{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}}}<span\; class="notranslate">\; ;</span>$

In the formula, r _m =m ₂ /m ₁ , r _k =k _t /k ₂ ;

Step B: Determine the optimal damping ratio ξ _os of the vehicle suspension system based on safety:

According to the sprung mass m ₂ of the vehicle's single-wheel suspension, the suspension stiffness k ₂ , the unsprung mass m ₁ , and the tire stiffness k _t , the optimal damping ratio ξ _os of the vehicle suspension system based on safety is determined, namely:

${\mathrm{<span\; class="notranslate">\; \&xi;</span>}}_{\mathrm{<span\; class="notranslate">\; os</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; )</span>}\sqrt{\frac{\mathrm{<span\; class="notranslate">\; R</span>}}{{\mathrm{<span\; class="notranslate">\; 4</span>}\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}}}<span\; class="notranslate">\; ;</span>$

In the formula, r _m =m ₂ /m ₁ , r _k =k _t /k ₂ , R=r _m r _k (r _m r _k -2-2r _m )+(1+r _m ) ³ ;

Step C: Determine the optimal damping ratio ξ _o of the vehicle suspension system based on comfort and safety:

According to ξ _oc determined in step A and ξ _os determined in step B, determine the optimal damping ratio ξ _o of the vehicle suspension system based on comfort and safety, namely:

ξ _o =ξ _oc +0.618(ξ _os -ξ _oc );

(2) Determine the damping ratio ξ _g of the leaf spring suspension system itself:

According to the suspension leaf spring loading and unloading deformation test, through the analysis and processing of the measured test data, the damping ratio of the leaf spring suspension system itself is obtained. The specific steps are as follows:

Step I: Using the leaf spring testing machine, according to the sprung mass m ₂ of the single-wheel leaf spring suspension under the rated load and the maximum load F _max = m ₂ g, the suspension leaf spring is gradually loaded and unloaded. , and test the deformation of the corresponding load at the same time, the load array F applied in the test and the measured deformation array X are respectively:

F={F(i)}, X={x(i)}, where i=1, 2, 3,..., n;

Among them, n is the number of displacement data collected or the number of applied loads in a cycle test.

Step II: According to the sprung mass m ₂ of the vehicle's single-wheel suspension and the suspension stiffness k ₂ , determine the natural frequency f ₀ of the leaf spring suspension system, namely:

${\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}}\sqrt{\frac{{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}}<span\; class="notranslate">\; ;</span>$

Step III: According to the maximum vibration velocity V of the suspension leaf spring under normal working conditions, the natural frequency f ₀ of the leaf spring suspension system determined in Step II, and the load array F={F(i )} and the measured deformation array X={x(i)}, where i=1, 2, 3,..., n, the equivalent damping coefficient C _de of the leaf spring is calculated, namely:

${\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; de</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}<span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span>}{{\mathrm{<span\; class="notranslate">\; V</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; ;</span>$

Step IV: According to the sprung mass m ₂ of the single-wheel suspension of the vehicle, the suspension stiffness k ₂ , and the C _de determined in Step III, determine the damping ratio ξ _g of the leaf spring suspension system itself, namely:

${\mathrm{<span\; class="notranslate">\; \&xi;</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; de</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}\sqrt{{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}}<span\; class="notranslate">\; ;</span>$

(3) Determine the damping ratio ξ _c that should be increased to achieve the optimum suspension system of the vehicle:

According to ξ _o determined in step C of step (1), and ξ _g determined in step IV of step (2), determine the damping ratio ξ _c that should be increased to achieve the optimum suspension system of the vehicle, namely:

ξ _c = ξ _o - ξ _g ;

(4) Design of the optimal damping coefficient C _d of the shock absorber of the leaf spring suspension system:

According to the sprung mass m ₂ of the single-wheel suspension of the vehicle, the installation angle α of the shock absorber, the lever ratio i, the natural frequency f ₀ of the leaf spring suspension system determined in step II of step (2), and the step ( The vehicle suspension system determined in 3) should increase the damping ratio _ξc to achieve the optimum, and design the optimal damping coefficient _Cd of the shock absorber of the leaf spring suspension system, namely:

${\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 4</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}{\mathrm{<span\; class="notranslate">\; \&xi;</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; cos</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}<span\; class="notranslate">\; .</span>$

The present invention has the advantage over prior art:

For the design of the optimal damping characteristics of the shock absorber of the vehicle leaf spring suspension system, no accurate and reliable design method has been given. It is difficult to obtain a reliable shock absorber that is matched with the leaf spring suspension system of the vehicle. The design method for the optimal damping characteristics of the shock absorber of the vehicle leaf spring suspension system established in the present invention, according to the optimal damping ratio required by the vehicle suspension system and the damping ratio of the leaf spring suspension system itself, the steel plate is analyzed and calculated The damping ratio that should be increased to achieve the optimal spring suspension system can obtain the optimal damping of the shock absorber required by the vehicle leaf spring suspension system, which improves the ride comfort of the vehicle. At the same time, repeated tests, verifications and modifications can be avoided. Reduce test costs for leaf spring dampers.

In order to better understand the present invention, the following will be further described in conjunction with the accompanying drawings.

Figure 1 is a design flow chart of the design method for the optimal damping characteristics of the shock absorber of the vehicle leaf spring suspension system;

Fig. 2 is the regression curve recorded by embodiment suspension leaf spring loading and unloading deformation test;

Fig. 3 is the simulation curve of the vertical vibration acceleration of the vehicle body changing with time before the embodiment matches the shock absorber;

Fig. 4 is a simulation curve of the variation of the vertical vibration acceleration of the vehicle body with time after the shock absorber is matched in the embodiment.

specific implementation plan

The design method for the optimal damping characteristics of the shock absorber of the vehicle leaf spring suspension system provided by the present invention will be further described in detail through examples below, and the design process is shown in FIG. 1 .

Example: A truck adopts a leaf spring suspension system, the sprung mass m ₂ =35000kg of the front axle single-wheel suspension, the unsprung mass m ₁ =3500kg, the suspension k ₂ =3618700N/m, and the tire stiffness k _t =32568300N /m, the maximum vibration velocity of the suspension leaf spring under normal working conditions V=0.5084m/s, the installation angle of the shock absorber α=10°, and the lever ratio i=0.9.

The design method of the optimal damping characteristic of the vehicle leaf spring suspension system shock absorber provided by the example of the present invention, its concrete steps are as follows:

(1) Determine the optimal damping ratio ξ _o required by the vehicle suspension system:

According to the vehicle parameters, determine the optimal damping ratio ξ _o required by the vehicle leaf spring suspension system. The specific steps are as follows:

Step A: Determine the optimal damping ratio ξ _oc of the vehicle suspension system based on comfort:

According to the sprung mass m ₂ = 35000kg, the unsprung mass m ₁ = 3500kg, the suspension stiffness k ₂ = 3618700N/m, and the tire stiffness k _t = 32568300N/m, determine the vehicle suspension based on comfort The optimal damping ratio ξ _oc of the frame system, namely:

${\mathrm{<span\; class="notranslate">\; \&xi;</span>}}_{\mathrm{<span\; class="notranslate">\; oc</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}\sqrt{\frac{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}}{{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0.1748</span>}<span\; class="notranslate">\; ;</span>$

In the formula, r _m =m ₂ /m ₁ , r _k =k _t /k ₂ ;

Step B: Determine the optimal damping ratio ξ _os of the vehicle suspension system based on safety:

According to the sprung mass m ₂ =35000kg of the single wheel suspension of the vehicle, the suspension stiffness k ₂ =3618700N/m, the unsprung mass m ₁ =3500kg, and the tire stiffness k _t =32568300N/m, determine the safety-based vehicle suspension The optimal damping ratio ξ _os of the frame system, namely:

${\mathrm{<span\; class="notranslate">\; \&xi;</span>}}_{\mathrm{<span\; class="notranslate">\; os</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; )</span>}\sqrt{\frac{\mathrm{<span\; class="notranslate">\; R</span>}}{{\mathrm{<span\; class="notranslate">\; 4</span>}\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0.4136</span>}<span\; class="notranslate">\; ;</span>$

In the formula, r _m =m ₂ /m ₁ , r _k =k _t /k ₂ , R=r _m r _k (r _m r _k -2-2r _m )+(1+r _m ) ³ ;

Step C: Determine the optimal damping ratio ξ _o of the vehicle suspension system based on comfort and safety:

According to ξ _oc =0.1748 determined in step A and ξ _os =0.4136 determined in step B, the optimal damping ratio ξ _o of the vehicle suspension system based on comfort and safety is determined, namely:

ξ _o =ξ _oc +0.618(ξ _os -ξ _oc )=0.3224;

(2) Determine the damping ratio ξ _g of the leaf spring suspension system itself:

According to the suspension leaf spring loading and unloading deformation test, through the analysis and processing of the measured test data, the damping ratio of the leaf spring suspension system itself is obtained. The specific steps are as follows:

Step I: Using the leaf spring testing machine, according to the sprung mass m ₂ of the single-wheel leaf spring suspension under the rated load and the maximum load F _max = m ₂ g, the suspension leaf spring is gradually loaded and unloaded. , and test the deformation of the corresponding load at the same time, the load array F={F(i)} and the measured displacement array X={x(i)} applied in the test are respectively:

F＝{F(i)}＝[0.640.172.634.035.286.787.98.9210.211.2512.313.5714.615.5916.8417.8518.8620.0921.0822.1123.3824.3925.426.6427.7228.7930.0231.0332.1133.4634.4735.5536.837.8538.9940.0941.4542.4443.7944. 9145.9947.2848.3849.4850.8851.9353.0554.3455.4256.5457.9458.9560.0761.5462.6663.7865.1266.1967.468.5169.8370.9772.1373.5474.5575.7677.1278.2879.480.7881.9683.0884.5785.5886.7288.2489.3890.691.8693.0894.3195.7296.997.9799.47100.67101.79103.29104.4105. 54107.03108.22109.4110.83111.99113.22114.71115.9117.08118.53119.71120.92122.46123.62124.8126.32127.54128.71130.27131.34132.63134.19135.4136.56138.07139.32140.55142.07143.21144.76146147.25148.72149.94151.24152.51154.09155.34156.43158.06159.29160.58162.1163.32164.49166.13167.38168.65170.12171.37172. 69174.27175.52176.68178.26179.56180.79182.37183.59184.82186.44187.7189.19190.48191.82193.47194.74195.83197.61198.84200.11201.61202.9204.25205.89207.12208.33209.93211.23212.51214.13215.29216.68218.33219.67221.01222.43223.8225.2226.8228.04229.31231232.23233.57 235.15236.4237.83239.48240.88242.01243.74245.06246.42248.04249.28250.66252.35253.6255.03256.7257.87259.25260.98262.39263.71265.24266.65268.01269.7270.94272.28274.03275.31276.69278.34279.57281.02282.75284.16285.34287.1288.49289.89291.58292.81294.24296297.34298.68299.89279.17264.63255.32250.26247. 08244.44241.78239.66237.85236.23234.85232.62231.26230.23228.47228.3227.07224.76223.23221.91220.66219.29218.15217.07215.65215.19213.12211.85210.64209.47208.13207.17205.47204.36203.26202.14200.69199.52198.27197.22196.45194.36193.55192.67191.01190.33189.51188.37186.14184.82183.53182.45180.83180.59178. 5177.19176.51175.1174.16172.17170.94170.06168.35166.94165.63164.55163.08161.94161.13160.03158.39156.92155.93154.9153.54152.55151.46150.03148.74147.57146.57145.2144.06143.12141.91140.6139.22138.19137.22136.69134.98134.06132.44131.34130.26128.93128.09126.87125.59124.69123.62122.63121.34120.4119. 43117.85117.39115.99114.62113.44112.13111.31110.15108.9107.96107.08106.09104.65103.79102.67101.42100.799.6798.5 96.8895.9395.6993.9892.7391.7490.7489.6688.6187.486.6385.5484.2483.4782.5681.6880.3279.4878.1777.0976.4675.1674.0473.1471.8571.170.1468.8568.1267.3365.9765.0964.2263.0161.9661.3660.0559.0258.1256.9356.1755.254.0453.1152.3951.2550.3549.4848.3547. 3346.4745.4844.543.6642.4841.7140.8639.6938.9338.0336.8836.0135.3134.1433.2732.4631.4530.5729.7828.7727.9427.0626.3125.2924.4523.4622.721.8820.920.0919.318.3817.5916.8615.8815.1814.513.5312.8312.0211.1410.49.749.038.137.436.735.885.224. 543.662.982.171.510.85];

X＝{x(i)}＝[0.01-0.030.370.71.051.511.862.192.62.953.293.714.054.384.85.135.445.846.176.496.897.27.517.98.238.568.949.249.569.9710.2810.610.9711.2811.611.9212.312.612. 9813.313.6113.9814.2914.61515.3115.6215.9916.316.621717.2917.6118.0118.3218.6319.0119.3219.6419.9520.3220.6320.9521.3321.6221.9422.3222.6322.9423.3123.6323.9324.3424.6124.9225.3325.6525.9626.3226.6326.9527.3327.6427.9328.3228.6428.9429.3429.6329.9330. 3330.6430.9431.3331.6231.9432.3332.6432.9433.3233.6333.9434.3434.6334.9335.3335.6435.9536.3436.6236.9437.3337.6437.9438.3138.6338.9439.3239.6140.0140.3340.644141.3141.6341.9542.3342.6542.9343.3243.6443.9544.3444.6444.9345.3345.6445.9546.3346.6246.9447. 3347.6447.9348.3148.6348.9449.3449.6349.9350.3350.645151.3151.6352.0252.3352.6153.0153.3253.625454.354.6155.0155.3255.65656.3156.6257.0157.2957.615858.3258.645959.3159.6360.0260.3260.6161.0161.3161.6362.0162.362.626363.3363.626464.3164.6265.0165.365.6166.0166. 366.6367.0167.3167.626868.3268.636969.3169.6270.0170.3170.671.0171.3171. 6272.0172.2972.617373.3273.6173.9874.374.6275.0275.3175.6176.0176.3276.6376.5976.3876.0575.775.3675.0874.7674.474.173.7373.4473.1572.7672.4772.1671.7871.5271.2370.8370.570.1969.8369.4869.268.8168.5168.2567.8267.5167.1866.8366.5266.2265.8265.5165. 2264.8764.5264.2363.8363.5463.2862.8462.5662.2461.8761.5761.2960.960.5860.2459.959.5859.2158.9258.5858.2257.8757.5657.2756.8656.5656.2655.8955.5455.2254.8954.5254.2253.8653.5653.2552.8452.5552.2451.8751.5651.2550.8950.5550.2349.949.5549.2148.8548. 5948.2547.8547.5447.2646.9146.5746.2845.8745.5645.2544.8844.5944.2643.8943.5943.2842.8942.6142.341.9141.5541.2440.940.5840.2439.8639.5839.2538.8838.5838.2837.9137.5937.2936.8936.5536.2335.9135.5835.1734.8734.6234.2333.8733.5733.2332.8932.5832.1831. 9331.5931.1930.930.5830.2229.929.629.2228.8828.6228.2327.8927.5927.1826.8926.626.1925.9125.5925.2124.924.624.2223.8723.6123.2322.8922.5922.1821.9121.5921.220.8820.5920.2219.9119.5919.2218.8818.5818.2217.8917.5917.1916.8916.616.215.915.5815. 1814.8714.614.213.8 913.5913.2212.912.6112.2211.911.5811.310.9110.5910.229.929.69.228.98.598.217.97.67.26.96.636.225.925.595.24.94.614.33.923.623.32.942.642.331.941.621.260.960.65]；

Among them, the regression curve measured by the suspension leaf spring loading and unloading deformation test obtained from the test is shown in Figure 2;

Step II: According to the sprung mass m ₂ =35000kg and suspension stiffness k ₂ =3618700N/m of the single-wheel suspension of the vehicle, determine the natural frequency f ₀ of the leaf spring suspension system, namely:

${\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}}\sqrt{\frac{{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1.6183</span>}\mathrm{<span\; class="notranslate">\; Hz</span>}<span\; class="notranslate">\; ;</span>$

Step III: According to the maximum vibration velocity V = 0.5084m/s under the normal working state of the suspension leaf spring, the natural frequency f ₀ of the leaf spring suspension system determined in Step II = 1.6183Hz, and the test obtained in Step I Load array F={F(i)} and deformation array X={x(i)}, where i=1, 2, 3,..., n, where n=460, the equivalent damping coefficient C _de of the leaf spring Do the calculation, that is:

${\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; de</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}<span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span>}{{\mathrm{<span\; class="notranslate">\; V</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 26530</span>}\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; .</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; ;</span>$

Among them, the simulation curve of the vertical vibration acceleration of the vehicle body changing with time is shown in Figure 3;

Step IV: According to the sprung mass m ₂ =35000kg of the single-wheel suspension of the vehicle, the suspension stiffness k ₂ =3618700N/m, and C _de =26530N.s/m determined in step III, determine the leaf spring suspension system own damping ratio ξ _g , namely:

${\mathrm{<span\; class="notranslate">\; \&xi;</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; de</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}\sqrt{{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0.0373</span>}<span\; class="notranslate">\; ;</span>$

(3) Determine the damping ratio ξ _c that should be increased to achieve the optimum suspension system of the vehicle: Step IV

According to ξ _o = 0.3224 determined in step C in step (1), and ξ _g = 0.0373 determined in step IV in step (2), determine the damping ratio ξ _c that should be increased to achieve the optimum suspension system of the vehicle, Right now:

ξ _c = ξ _o - ξ _g = 0.2851;

(4) Design of the optimal damping coefficient C _d of the shock absorber of the leaf spring suspension system:

According to the sprung mass m ₂ of the single-wheel suspension of the vehicle = 35000kg, the installation angle α of the shock absorber of the leaf spring suspension system of the vehicle = 10°, the lever ratio i = 0.9, the f determined in the II step in the step (2) ₀ = 1.6183Hz, and the damping ratio ξ _c = 0.2851 determined in step (3), the optimal damping coefficient C _d of the shock absorber of the leaf spring suspension system is designed, namely:

${\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 4</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}{\mathrm{<span\; class="notranslate">\; \&xi;</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; cos</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 258310</span>}\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; .</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; .</span>$

Through matlab/simulink, the simulation analysis of the vertical vibration acceleration of the vehicle body before and after matching the designed shock absorber of the vehicle leaf spring suspension is carried out. Among them, the simulation curve of the vertical vibration acceleration of the vehicle body before matching the designed shock absorber changes with time, As shown in Figure 3; the simulation curve of the vertical vibration acceleration of the vehicle body with time after matching the designed shock absorber is shown in Figure 4; it can be seen that the vertical vibration acceleration of the vehicle body of the leaf spring suspension is significantly reduced after matching the shock absorber It shows that the design method of the optimal damping characteristics of the vehicle leaf spring suspension system shock absorber is accurate and can significantly improve the ride comfort of the vehicle.

Claims (1)

1. the method for designing of vehicle Leaf Spring Suspension System vibration damper optimum damping characteristic, its specific design step is as follows:

(1) determine that the needed optimal damper of vehicle suspension system compares ξ _o:

According to vehicle parameter, determine that the needed optimal damper of vehicle Leaf Spring Suspension System compares ξ _o, concrete steps are as follows:

A step: determine the vehicle suspension system optimum damping ratio ξ based on comfortableness _oc:

According to the sprung mass m of vehicle single-wheel suspension ₂, suspension rate k ₂, unsprung mass m ₁, and tire stiffness k _t, determine the vehicle suspension system optimum damping ratio ξ based on comfortableness _oc, that is:

${\mathrm{\&xi;}}_{\mathrm{oc}}=\frac{1}{2}\sqrt{\frac{1+r_m}{r_m{r}_k}};$

In formula, r _m=m ₂/ m ₁, r _k=k _t/ k ₂;

B step: determine the vehicle suspension system optimum damping ratio ξ based on security _os:

According to the sprung mass m of vehicle single-wheel suspension ₂, suspension rate k ₂, unsprung mass m ₁, and tire stiffness k _t, determine the vehicle suspension system optimum damping ratio ξ based on security _os, that is:

${\mathrm{\&xi;}}_{\mathrm{os}}=\frac{1}{(1+r_m)}\sqrt{\frac{R}{{4r}_m{r}_k}};$

In formula, r _m=m ₂/ m ₁, r _k=k _t/ k ₂, R=r _mr _k(r _mr _k-2-2r _m)+(1+r _m) ³;

C step: determine that the vehicle suspension system optimal damper based on comfortableness and security compares ξ _o:

According to determined ξ in A step _ocwith determined ξ in B step _os, determine that the vehicle suspension system optimal damper based on comfortableness and security compares ξ _o, that is:

ξ _o＝ξ _oc+0.618(ξ _os-ξ _oc)；

(2) determine the damping ratio ξ that Leaf Spring Suspension System self has _g:

Load and unloading deformation test according to suspension leaf spring, by analysis and the processing of the test figure to measured, obtain the damping ratio that Leaf Spring Suspension System self has, concrete steps are as follows:

I step: utilize leaf spring testing machine, according to the sprung mass m of single-wheel Leaf Spring Suspension under rated load ₂and the maximum load F bearing _max=m ₂g, carries out progressively loading and unloading test to suspension leaf spring, the deflection of respective loads is tested simultaneously, and the load array F that test applies and measured distortion array X, be respectively:

F={F (i) }, X={x (i) }, wherein i=1,2,3 ..., n;

Wherein, the number of displacement data or the number of institute imposed load of n for gathering in one-period cyclic test.

II step: according to the sprung mass m of vehicle single-wheel suspension ₂, suspension rate k ₂, determine the natural frequency f of Leaf Spring Suspension System ₀, that is:

$f_0=\frac{1}{2\mathrm{\&pi;}}\sqrt{\frac{k_2}{m_2}};$

III step: according to the maximum velocity V under suspension leaf spring normal operating conditions, the natural frequency f of definite Leaf Spring Suspension System in II step ₀, and in I step, test applied load array F={F (i) } and measured distortion array X={x (i), wherein i=1,2,3 ..., n, to the Equivalent damping coefficient C of leaf spring _decalculate, that is:

$C_{\mathrm{de}}=\frac{{2f}_0\underset{j=1}{\overset{n-1}{\mathrm{\&Sigma;}}}\left|F\left(j\right)\right|.|x(j+1)-x\left(j\right)|}{V^2};$

IV step: according to the sprung mass m of vehicle single-wheel suspension ₂, suspension rate k ₂, and determined C in III step _de, determine the damping ratio ξ that Leaf Spring Suspension System self has _g, that is:

${\mathrm{\&xi;}}_g=\frac{C_{\mathrm{de}}}{2\sqrt{k_2{m}_2}};$

(3) determine that vehicle suspension system reaches the damping ratio ξ that optimum should increase _c:

According to the determined ξ of C step in step (1) _o, and the determined ξ of IV step in step (2) _g, determine that vehicle suspension system reaches the damping ratio ξ that optimum should increase _c, that is:

ξ _c＝ξ _o-ξ _g；

(4) Leaf Spring Suspension System vibration damper optimal damping constant C _ddesign:

According to the sprung mass m of vehicle single-wheel suspension ₂, the setting angle α of vibration damper, lever ratio i, the natural frequency f of the determined Leaf Spring Suspension System of II step in step (2) ₀, and in step (3), determined vehicle suspension system reaches the damping ratio ξ that optimum should increase _c, to the optimal damping constant C of Leaf Spring Suspension System vibration damper _ddesign, that is:

$C_d=\frac{4\mathrm{\&pi;}{\mathrm{\&xi;}}_c{f}_0{m}_2}{i^2{\cos }^2\mathrm{\&alpha;}}.$