CN103376173B - The measuring method of internal friction resistance during a kind of vehicle sliding - Google Patents

Abstract

The measuring method of internal friction resistance when the present invention proposes a kind of vehicle sliding, the method be the vehicle of certain mass is placed on track with initial velocity and carry out respectively many groups slide and measure vehicle at every turn by speed to 0, get arithmetic mean after the coasting distance of 0; And then calculate coasting distance eigenwert and running resistance eigenwert, then ask the resistance to rolling that automobile slides with this quality; Change vehicle mass, repeat above-mentioned steps, obtain the resistance to rolling after changing quality, both recyclings difference obtains rolling resistance coefficient of vehicle, the product of vehicle weight and coefficient of rolling resistance is finally deducted by resistance to rolling, draw inner frictional resistance of vehicle, measuring method of the present invention is simple, cost is low, and measuring accuracy is high simultaneously.

Description

The measuring method of internal friction resistance during a kind of vehicle sliding

Technical field

The present invention relates to the test of vehicle operating parameters, the measuring method of internal friction resistance when particularly relating to a kind of vehicle sliding.

Background technology

In vehicle travel process; usually can be subject to the impact of resistance to rolling and air resistance, wherein resistance to rolling is transformed into the drag overall (hereinafter referred to as internal friction resistance) at wheel edge in the face of the resistance of vehicle and vehicle transmission system brake system internal friction of unifying with comprising.The measuring method of current internal friction resistance is generally the direct method of measurement: survey crew makes car be in neutral, then utilize lifting machine that vehicle is lifted off ground, re-use tautness meter and slowly pull wheel in felly, record tautness meter numerical value, the pulling force finally recorded by each wheel is added and obtains internal friction.The shortcoming of said method is that when measuring, vehicle remains static, the unify friction force of each friction pair of brake system of vehicle transmission system is similar to static friction, therefore this method accurately can not reflect the internal friction under vehicle running state, bigger than normal than the internal friction under real vehicle running state.

Summary of the invention

The inner frictional resistance of vehicle that the obtains problem bigger than normal compared with actual value is measured in order to solve in prior art, thus the measuring method of internal friction resistance when the present invention proposes a kind of vehicle sliding, comprise the following steps:

Quality, with reference to the testing standard of GBT-12536 automobile slide test method(s), is m by step one ₁vehicle with initial velocity v ₀and v ₀/ a carries out neutral respectively and comes and goes coasting test along test track, be respectively once one group to come and go to slide, carry out many groups respectively, registration of vehicle is at every turn by speed v ₀to 0, v ₀/ a, to the coasting distance of 0, calculates vehicle by speed v ₀the arithmetic mean S of the many groups coasting distance to 0 and vehicle are by speed v ₀the arithmetic mean of the many group coasting distance of/a to 0 wherein a be greater than 1 arbitrary constant;

Step 2 calculates coasting distance eigenwert r according to formula (1),

$r=\frac{S}{S_{v_0/a}}---\left(1\right)$

Coasting distance eigenwert r is substituted in formula (2) and calculates running resistance eigenwert q,

$r=\frac{\ln (1+q)}{\ln (1+q/a^2)}---\left(2\right)$

The running resistance eigenwert q calculated in formula (2) is substituted into formula (3) and calculates k ₂,

$k_2=\frac{\mathrm{\δm}}{2\×S\×{3.6}^2}\ln (1+q)---\left(3\right)$

Wherein, δ is the vehicle correction coefficient of rotating mass considering vehicle wheel rotation inertia, and its pervasive computing formula is wherein, ∑ I _wfor vehicle wheel rotation inertia (those skilled in the art obtain by test), r is radius of wheel.For δ, the optional interior empirical value of choosing a job of those skilled in the art, also can basis calculate.

By the k that formula (3) calculates ₂it is m that substitution formula (4) calculates vehicle mass ₁time resistance to rolling k _0m1,

$k_0=\frac{k_2{v_0}^2}{q}---\left(4\right)$

Wherein, k ₂v ² ₀for air resistance;

Step 3 changes carload, by the quality m of vehicle in above-mentioned steps ₁be adjusted to m ₂, repeating step one and obtaining vehicle mass according to step 2 is m ₂time resistance to rolling k _0m2;

Step 4 obtains rolling resistance coefficient of vehicle f according to formula (5)

$f=\frac{k_{0m2}-k_{0m1}}{(m_2-m_1)g}---\left(5\right);$

Internal friction resistance F when step 5 obtains vehicle sliding according to following formula _{internal resistance}

F _{internal resistance}=k _0m1-fm ₁g=k _0m2-fm ₂g (6)

In formula (6), g is acceleration of gravity.

As a kind of preferred version, during vehicle sliding of the present invention, the measuring method of internal friction resistance is before carry out step one, vehicle is travelled at least 30min with the speed of a motor vehicle of average 50km/h ~ 80km/h and carries out preheating; After vehicle preheating, confirm that whether vehicle preheating is abundant, be specially and on horizontal track, vehicle repeatedly slided with identical initial velocity, measure each coasting distance of vehicle, if the repeatedly coasting distance of vehicle is each other without increasing trend, then vehicle preheating is abundant, carries out vehicle sliding test.

As a kind of preferred version, during vehicle sliding of the present invention, in the measuring method step one of internal friction resistance and step 3, the group number of each coasting test of vehicle is no less than 5 groups; Described m ₁for vehicle maximum design total mass, m ₂for Vehicle preparation quality adds the quality of a human pilot.

As a kind of preferred version, during vehicle sliding of the present invention internal friction resistance measuring method in the value of δ described in step one get 1.02 ~ 1.05.

As a kind of preferred version, in the measuring method of rolling resistance coefficient of vehicle of the present invention, a=1.25 ~ 5; More preferably a=2, and calculate running resistance eigenwert q with formula (7):

$q=\frac{-1.302r^2+4.771r+1.973}{r^2-2.148r+1.069}---\left(7\right)$

As a kind of preferred version, during vehicle sliding of the present invention internal friction resistance measuring method described in the vehicle sliding test of step one and step 3 carry out continuously.

As a kind of preferred version, during vehicle sliding of the present invention internal friction resistance measuring method in selection environment temperature fluctuation be less than the environment of 1 DEG C under carry out vehicle sliding test.

During vehicle sliding of the present invention internal friction resistance measuring method in only need by vehicle with initial velocity v ₀and v ₀/ a carries out the sliding test of many groups respectively, and registration of vehicle is at every turn by speed v ₀to 0, v ₀the coasting distance of/a to 0, then described formula is utilized to calculate vehicle rolling resistance, then vehicle mass is changed, repeat the step before vehicle mass change, calculate the resistance to rolling after vehicle mass change, then calculate two resistances to rolling are substituted in formula (5) and revise, draw vehicle true rolling resistance coefficient, and then utilizing formula (6) to obtain inner frictional resistance of vehicle, described measuring method is simple, and accurately can draw inner frictional resistance of vehicle.

Embodiment

Below for the specific embodiment of the present invention is described in detail.Should be understood that, embodiment described herein, only for instruction and explanation of the present invention, is not limited to the present invention.

The testing standard of the measuring method reference GBT-12536 automobile slide test method(s) of inner frictional resistance of vehicle coefficient of the present invention, but vehicle slide initial velocity, coasting test group number and slide time vehicle-mounted load can change, the present invention mainly with reference to GBT-12536 test condition and make use of the testing equipment of GBT-12536 coasting test.

During vehicle sliding of the present invention, the measuring method of internal friction resistance comprises the following steps:

Quality, with reference to the testing standard of GBT-12536 automobile slide test method(s), is m by step one ₁vehicle with initial velocity v ₀and v ₀/ a carries out neutral respectively and comes and goes coasting test along test track, be respectively once one group to come and go to slide, carry out many groups respectively, registration of vehicle is at every turn by speed v ₀to 0, v ₀/ a, to the coasting distance of 0, calculates vehicle by speed v ₀the arithmetic mean S of the many groups coasting distance to 0 and vehicle are by speed v ₀the arithmetic mean of the many group coasting distance of/a to 0 wherein a be greater than 1 arbitrary constant;

In step one before test vehicle enters test tracks, a selected direction is positive dirction, its reverse direction is negative direction, simultaneously, enter the speed of a motor vehicle before test tracks and should slide the large 5km/h ~ 10km/h of initial velocity than the test of vehicle, ensure that the speed of a motor vehicle that coasting test starts is selected slide initial velocity substantially like this, the arithmetic mean of a coasting distance of picking up the car after carrying out repeatedly coasting test makes the data that record more accurate; The physical record of vehicle sliding test is when vehicle is after a direction coast stop, record coasting distance, after vehicle slides end in the opposite direction, record out coasting distance, and obtain the arithmetic mean of the coasting distance of this group of vehicle, after carrying out many group tests, the vehicle coasting distance arithmetic mean that often group calculates on average is drawn again the final arithmetic mean of vehicle, the vehicle sliding distance calculated like this is closer to actual value, for arithmetic mean computing formula, those skilled in the art can obtain in conjunction with prior art;

In step one, measuring car is by speed v ₀the arithmetic mean S of the many groups coasting distance to 0 and vehicle are by speed v ₀the arithmetic mean of the many group coasting distance of/a to 0 can once carry out, namely with initial velocity v ₀carry out organizing to come and go sliding experiment, then access speed v from experimental record more ₀to 0, v ₀the coasting distance of/a to 0, and then calculate average coasting distance.

Step 2 calculates coasting distance eigenwert r according to formula (1),

$r=\frac{S}{S_{v_0/a}}---\left(1\right)$

Coasting distance eigenwert r is substituted in formula (2) and calculates running resistance eigenwert q,

$r=\frac{\ln (1+q)}{\ln (1+q/a^2)}---\left(2\right)$

The running resistance eigenwert calculated in formula (2) is substituted into formula (3) and calculates k ₂,

$k_2=\frac{\mathrm{\δm}}{2\×S\×{3.6}^2}\ln (1+q)---\left(3\right)$

Wherein, δ is the vehicle correction coefficient of rotating mass considering vehicle wheel rotation inertia,

By the k that formula (3) calculates ₂it is m that substitution formula (5) calculates vehicle mass ₁time resistance to rolling k _0m1,

$k_0=\frac{k_2{v_0}^2}{q}---\left(4\right)$

Wherein, k ₂v ² ₀for air resistance;

In step 2, the general fit calculation formula of δ is wherein, ∑ I _wfor vehicle wheel rotation inertia (those skilled in the art can obtain in conjunction with prior art test, no longer describe in detail here), r is radius of wheel.It is pointed out that for δ, those skilled in the art both directly can select empirical value in the industry, also can basis calculate.Through long-term test, invention technician show that the δ in formula (3) generally gets 1.02 ~ 1.05, need not calculate again, reduces calculated amount.

Step 3 changes carload, by the quality m of vehicle in above-mentioned steps ₁be adjusted to m ₂, repeating step one and obtaining vehicle mass according to step 2 is m ₂time resistance to rolling k _0m2, vehicle mass is m ₂time the algorithm of resistance to rolling be m with calculating vehicle mass in step 2 ₁time resistance to rolling specific algorithm identical,

Step 3 adjusts vehicle mass, for step 4 utilizes differential technique to ask vehicle true rolling resistance coefficient to prepare;

The vehicle rolling resistance obtained in above-mentioned steps is the actual resistance to rolling of vehicle and internal friction resistance sum, therefore, needs the real coefficient of rolling resistance being obtained vehicle by the formula of step 4.

Step 4 obtains rolling resistance coefficient of vehicle f according to formula (5)

$f=\frac{k_{0m2}-k_{0m1}}{(m_2-m_1)g}---\left(5\right)$

Wherein k _0m2for vehicle mass is m ₂time resistance to rolling, k _0m1for vehicle mass is m ₁time resistance to rolling.

Step 4 can arrive through formula correction and remove inner frictional resistance of vehicle, and then draws actual coefficient of rolling resistance;

Internal friction resistance F when step 5 obtains vehicle sliding according to following formula _{internal resistance}

F _{internal resistance}=k _0m1-fm ₁g=k _0m2-fm ₂g (6)

In formula (6), f is rolling resistance coefficient of vehicle, and g is acceleration of gravity.

K in step 5 _0m1and k _0m2all comprise resistance to rolling and the internal friction resistance of vehicle, therefore need the internal friction resistance F being calculated vehicle by formula (6) _{internal resistance}.

During vehicle sliding of the present invention, the measuring method of internal friction resistance first carries out preheating before vehicle test, ensure that each group of data that coasting test is measured are basically identical, avoid the increase of coasting test workload, concrete preheating method is that vehicle is travelled at least 30min with the speed of a motor vehicle of average 50km/h ~ 80km/h, and certain preheating method must the combined factors consideration such as the height above sea level on binding tests ground, the season of test.

After vehicle preheating, in order to vehicle whether fully preheating accurately can be judged, the present invention proposes the whether sufficient a kind of determination methods of preheating, be specially and on horizontal track, vehicle repeatedly slided with identical initial velocity, if the repeatedly coasting distance of vehicle is each other without increasing trend, then vehicle preheating is abundant, carries out vehicle sliding test; In addition after vehicle test data record starts, if a data exception in one group of data, these group data are deleted, and ensure that data measured is closer to actual conditions, has referred to that foreign matter enters test track and causes measurement data distortion here extremely.

During vehicle sliding of the present invention internal friction resistance measuring method in, the group number of coasting test can be one or more groups, such as, but in order to make the coasting distance arithmetic mean of vehicle more accurate, this method preferred coasting test group number is more than or equal to 5, and vehicle is with initial velocity v ₀5 groups are slided, when after carload change, equally with initial velocity v along test track ₀5 groups are respectively slided along horizontal track.

As a kind of preferred version, during vehicle sliding of the present invention internal friction resistance measuring method described in m ₁for vehicle maximum design total mass, m ₂for Vehicle preparation quality adds the quality of a human pilot, the denominator value difference in larger guarantee formula (6) of poor quality is larger, and the rolling resistance coefficient of vehicle finally calculated is more accurate, and then the inner frictional resistance of vehicle finally calculated is more accurate.

In order to ensure the coasting distance of each coasting test of vehicle closer to, vehicle will keep when sliding substantially linearly travelling, and the as far as possible dynamic bearing circle less of the driver in vehicle, avoids using braking function in test simultaneously, cause the coasting distance portion of measurement accurate.

The present invention in principle a can get the arbitrary constant being greater than 1, but obvious a is only slightly larger than 1 close infinity then close to 0, in two kinds of situations less error will cause the comparatively big error of coasting distance eigenwert r.Through attempting, during a=1.25 ~ 5, test accuracy is better, therefore recommends to adopt the value within the scope of this.

Generally, directly ask q not too easy according to (2) formula, can the method approximate solutions such as curve be adopted.A=2 is chosen in recommendation, and calculates running resistance eigenwert q with following formula (7):

$q=\frac{-1.302r^2+4.771r+1.973}{r^2-2.148r+1.069}---\left(7\right)$

Although there is the fitting formula that precision is higher, often structure is more complicated.(7) precision of formula is enough to meet calculation requirement, and structure is simple, can save by the step of computer software to formula (2) the Fitting Calculation, therefore, and preferred a=2, and use formula calculate running resistance eigenwert q.

In the present invention, the value of described δ gets 1.02 ~ 1.05, and this invention test of many times according to the present invention draws, the numerical value directly choosing this scope carries out calculating and can reduce calculated amount.

During vehicle sliding of the present invention internal friction resistance measuring method described in the vehicle sliding test of step one and step 3 carry out continuously, each group of coasting distance difference that coasting test records becomes greatly to avoid temperature Change affect, to such an extent as to loses contact with reality.

During vehicle sliding of the present invention internal friction resistance measuring method in preferred external environment condition parameter as follows:

Temperature is between 5 DEG C ~ 32 DEG C; Atmospheric humidity should be less than 95%; Atmospheric pressure should be greater than 91.8kPa; Mean wind speed should be less than 3m/s, and maximum wind velocity should be less than 5m/s, and the mean wind speed of test roads vertical direction should be less than 2m/s, and wind speed should be measured exceeding 0.7m place, road surface; Should clean, dry, smooth, carry out with on the linear road of pitch or concrete pavement, the long 2km ~ 3km of road, be widely not less than 8m, head fall is within 0.1%.

Cause vehicle sliding to test the error of the data recorded to reduce external environmental factor, the condition that selection environment temperature of the present invention fluctuation is less than 1 DEG C carries out vehicle sliding test.

The following detailed description of the derivation of (2) formula.

Initial velocity v ₀corresponding coasting distance is:

$S_{v_0}=\frac{\mathrm{\δm}}{2\×k_2\×{3.6}^2}\ln \frac{k_0+k_2{v_0}^2}{k_0}=\frac{\mathrm{\δm}}{2\×k_2\×{3.6}^2}\ln (1+q)$

Initial velocity corresponding coasting distance is:

$S_{v_0/a}=\frac{\mathrm{\δm}}{2\×k_2\×{3.6}^2}\ln \frac{k_0+k_2{v_0}^2/a^2}{k_0}=\frac{\mathrm{\δm}}{2\×k_2\×{3.6}^2}\ln (1+q/a^2)$

Then:

$\frac{S_{v_0}}{S_{v_0/a}}=\frac{\ln (1+q)}{\ln (1+q/a^2)}$

Order $r=\frac{S_{v_0}}{S_{v_0/a}},$ Then:

$r=\frac{\ln (1+q)}{\ln (1+q/a^2)}---\left(2\right)$

In formula:

R---coasting distance eigenwert, calculates according to (1) formula;

A---be greater than the arbitrary constant of 1, consistent with a value in (1) formula.

Be concrete example of the present invention below

Environmental baseline: temperature is 30 DEG C, air pressure is 100kPa, gentle breeze (< 2m/s).

Tire pressure adjusts: guarantee tire at 30 DEG C and, after abundant thermal equilibrium, cold conditions tire pressure is adjusted to vehicle manufacturers recommendation 220kPa.

Vehicle mass m ₁: a human pilot taken by instruction carriage, then loads sandbag and makes vehicle mass reach the maximum design total mass 2050kg of this car.

Consider vehicle correction coefficient of rotating mass: trying to achieve correction coefficient of rotating mass according to vehicle wheel rotation inertia and radius is 1.023.

Vehicle preheating: make vehicle travel 30 minutes with the average speed of 60km/h, to make the abundant preheating of tire.

Be carry out coasting test under the condition of m1 and record coasting distance at vehicle mass: on level, dry bituminous pavement, carry out 5 groups of (come and go and be respectively once one group) coasting tests, initial speed of a motor vehicle 50km/h (i.e. v ₀=50km/h); The coasting distance of 50km/h to 0km/h and the coasting distance of 25km/h (during a=2) to 0km/h when using Portable GPS equipment (sample frequency 10Hz) to record each coasting test.The data of record are as follows:

Calculating slides the coasting distance mean value S (unit: m) and with initial velocity 25km/h slide the coasting distance mean value to 0km/h to 0km/h with initial velocity 50km/h (unit: m)

$S=\frac{699.0+704.7+695.1+703.4+710.4}{5}=702.5;$

$S_{v_0/2}=\frac{213.5+218.2+222.6+221.4+212.7}{5}=217.7;$

Calculating vehicle mass according to formula (1) is m ₁time coasting distance eigenwert r

$r=\frac{S}{S_{V_0/2}}=\frac{702.5}{217.7}=3.227;$

Obtaining vehicle mass according to formula (7) is m ₁time running resistance eigenwert q:

$q=\frac{-{1.302r}^2+4.771r+1.973}{r^2-2.148r+1.069}=\frac{-1.302*{3.227}^2+4.771*3.227+1.973}{{3.227}^2-2.148*3.227+1.069}=0.7948;$

Obtaining vehicle mass according to formula (4) is m ₁time k ₂

$k_2=\frac{\mathrm{\&delta;}{m}_1}{2\&times;S\&times;{3.6}^2}\mathrm{In}(1+q)=\frac{1.023*2050}{2\&times;702.5\&times;{3.6}^2}\mathrm{In}(1+0.7948)=0.06736;$

Obtaining vehicle mass according to formula (5) is m ₁time k _0m1

$k_{0m1}=\frac{k_2{v}_0^2}{q}=\frac{0.06736*{50}^2}{0.7948}=211.9.$

Change vehicle mass, vehicle mass is adjusted to m ₂, m ₂for unloading m ₁in whole sandbags, the vehicle mass only after a surplus human pilot is 1676kg.

Consider vehicle correction coefficient of rotating mass: trying to achieve correction coefficient of rotating mass according to vehicle wheel rotation inertia and radius is 1.029.

By vehicle preheating: travel 30 minutes with the average speed of 70km/h, to make the abundant preheating of tire.

The method of coasting test is identical when being all m1 with vehicle mass with experiment condition, does not repeat them here, and only logging test results is as shown in following table 3,4.

Calculating slides the coasting distance mean value S (unit: m) and with initial velocity 25km/h slide the coasting distance mean value to 0km/h to 0km/h with initial velocity 50km/h (unit: m)

$S=\frac{654.1+656.5+657.7+663.9+653.3}{5}=657.1;$

$S_{v_0/2}=\frac{205.7+204.2+210.6+214.1+211.3}{5}=209.2;$

Calculating vehicle mass according to formula (1) is m ₂time coasting distance eigenwert r

$r=\frac{S}{S_{v_0/2}}=\frac{657.1}{209.2}=3.141;$

Calculating vehicle mass according to formula (7) is m ₂time running resistance eigenwert q

$q=\frac{-1.302r^2+4.771r+1.973}{r^2-2.148r+1.069}=\frac{-1.302*3.141^2+1.771*3.141+1.973}{{3.141}^2-2.148*3.141+1.069}=0.9371;$

Calculating vehicle mass according to formula (3) is m ₂time k ₂

$k_2=\frac{\mathrm{\&delta;}{m}_2}{2\&times;S\&times;{3.6}^2}\mathrm{In}(1+q)=\frac{1.029*1676}{2\&times;657\&times;{3.6}^2}\mathrm{In}(1+0.9371)=0.06695;$

Calculating vehicle mass according to formula (4) is m ₂time k _0m2

$k_{0m2}=\frac{k_2{v}_0^2}{q}=\frac{0.06695*{50}^2}{0.9371}=178.6;$

Rolling resistance coefficient of vehicle f is obtained according to formula (5)

$f=\frac{k_{0m2}-k_{0m1}}{(m_2-m_1)g}=\frac{211.9-178.6}{(2050-1676)\&times;9.8}=0.00909.$

Internal friction resistance F when finally obtaining vehicle sliding according to formula (6) _{internal resistance}

F _{internal resistance}=k _0m2-fm ₂g=211.9-0.00909 × 2050 × 9.8=29.3.

During vehicle sliding of the present invention, the measuring method of internal friction resistance only needs vehicle with initial velocity v ₀and v ₀/ a carries out many groups respectively and slides, and registration of vehicle is at every turn by speed v ₀to 0, v ₀the coasting distance of/a to 0, just can calculate a resistance to rolling of vehicle, calculate another resistance to rolling of vehicle by the step before vehicle mass change after changing the quality of vehicle, undertaken revising by formula (5) and obtain the real coefficient of rolling resistance of vehicle, because the resistance to rolling measured contains the real resistance to rolling of vehicle and internal friction resistance, and then calculate inner frictional resistance of vehicle with formula (6), this method is measured simple, and range observation error is little, comparatively accurate, simultaneously through revising, draw inner frictional resistance of vehicle more accurately, measure inner frictional resistance of vehicle to reduce resistance of taxing when Car design, thus reduction oil consumption, improve fuel economy and reference is accurately provided.

More than describe the preferred embodiment of the present invention in detail; but the present invention is not limited to the detail in above-mentioned embodiment, within the scope of technical conceive of the present invention; can carry out multiple simple variant to technical scheme of the present invention, these simple variant all belong to protection scope of the present invention.

It should be noted that in addition, each concrete technical characteristic described in above-mentioned embodiment, in reconcilable situation, can be combined by any suitable mode, in order to avoid unnecessary repetition, the present invention illustrates no longer separately to various possible array mode.In addition, also can carry out combination in any between various different embodiment of the present invention, as long as it is without prejudice to thought of the present invention, it should be considered as content disclosed in this invention equally.

Claims (10)

1. the measuring method of internal friction resistance during vehicle sliding, is characterized in that, comprise the following steps:

Quality, with reference to the testing standard of GBT-12536 automobile slide test method(s), is m by step one ₁vehicle with initial velocity v ₀and v ₀/ a carries out neutral respectively and comes and goes coasting test along test track, be respectively once one group to come and go to slide, carry out many groups respectively, registration of vehicle is at every turn by speed v ₀to 0, v ₀/ a, to the coasting distance of 0, calculates vehicle by speed v ₀the arithmetic mean S of the many groups coasting distance to 0 and vehicle are by speed v ₀the arithmetic mean of the many group coasting distance of/a to 0 wherein a be greater than 1 arbitrary constant;

Step 2 calculates coasting distance eigenwert r according to formula (1),

$r=\frac{S}{S_{v_0/a}}---\left(1\right)$

Coasting distance eigenwert r is substituted in formula (2) and calculates running resistance eigenwert q,

$r=\frac{\ln (1+q)}{\ln (1+q/a^2)}---\left(2\right)$

The running resistance eigenwert q calculated in formula (2) is substituted into formula (3) and calculates k ₂,

$k_2=\frac{\mathrm{\&delta;m}}{2\&times;S\&times;{3.6}^2}\ln (1+q)---\left(3\right)$

Wherein, δ is the vehicle correction coefficient of rotating mass considering vehicle wheel rotation inertia,

By the k that formula (3) calculates ₂it is m that substitution formula (4) calculates vehicle mass ₁time resistance to rolling k _0m1,

$k_{0m1}=\frac{k_2{v_0}^2}{q}---\left(4\right)$

Wherein, k ₂v ² ₀for air resistance;

Step 3 changes carload, by the quality m of vehicle in above-mentioned steps ₁be adjusted to m ₂, repeating step one and obtaining vehicle mass according to step 2 is m ₂time resistance to rolling k _0m2;

Step 4 obtains rolling resistance coefficient of vehicle f according to formula (5)

$f=\frac{k_{0m2}-k_{0m1}}{(m_2-m_1)g}---\left(5\right);$

Internal friction resistance F when step 5 obtains vehicle sliding according to following formula _{internal resistance}

F _{internal resistance}=k _0m1-fm ₁g=k _0m2-fm ₂g (6)

In formula (6), g is acceleration of gravity.

2. the measuring method of internal friction resistance during vehicle sliding according to claim 1, is characterized in that, before carry out step one, vehicle is travelled at least 30min with the speed of a motor vehicle of average 50km/h ~ 80km/h and carries out preheating.

3. the measuring method of inner frictional resistance of vehicle according to claim 2, it is characterized in that, after vehicle preheating, confirm that whether vehicle preheating is abundant, be specially and on horizontal track, vehicle repeatedly slided with identical initial velocity, measure each coasting distance of vehicle, if the repeatedly coasting distance of vehicle is each other without increasing trend, then vehicle preheating is abundant, carries out vehicle sliding test.

4. the measuring method of internal friction resistance during vehicle sliding according to claim 1, is characterized in that, in step one and step 3, the group number of each coasting test of vehicle is no less than 5 groups.

5. the measuring method of internal friction resistance during vehicle sliding according to claim 1, is characterized in that, described m ₁for vehicle maximum design total mass, m ₂for Vehicle preparation quality adds the quality of a human pilot.

6. the measuring method of coefficient of air resistance during vehicle sliding according to claim 1, is characterized in that, a=1.25 ~ 5 described in step one.

7. the measuring method of coefficient of air resistance during vehicle sliding according to claim 6, is characterized in that, the a=2 described in step one, and calculates running resistance eigenwert q with following formula (7),

$q=\frac{-1.302r^2+4.771r+1.973}{r^2-2.148r+1.069}---\left(7\right).$

8. the measuring method of internal friction resistance during vehicle sliding according to claim 1, is characterized in that, the vehicle sliding test of described step one and step 3 is carried out continuously.

9. the measuring method of internal friction resistance during vehicle sliding according to claim 1, it is characterized in that, the value of described δ gets 1.02 ~ 1.05.

10. the measuring method of internal friction resistance during vehicle sliding according to claim 1, it is characterized in that, selection environment temperature fluctuation carries out vehicle sliding test under being less than the environment of 1 DEG C.