CN116561480A - Passenger car braking distance test and calculation method - Google Patents
Passenger car braking distance test and calculation method Download PDFInfo
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- CN116561480A CN116561480A CN202310411301.2A CN202310411301A CN116561480A CN 116561480 A CN116561480 A CN 116561480A CN 202310411301 A CN202310411301 A CN 202310411301A CN 116561480 A CN116561480 A CN 116561480A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M17/00—Testing of vehicles
- G01M17/007—Wheeled or endless-tracked vehicles
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- G—PHYSICS
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation
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Abstract
The invention discloses a method for testing and calculating a braking distance of a passenger car, which belongs to the technical field of vehicle safety and specifically comprises the following steps: step one: giving initial parameters; step two: calculating a braking distance in a braking coordination stage; step three: calculating a braking distance in a braking establishment stage; step four: calculating a braking distance in a braking maintaining stage; step five: the total braking distance is calculated. According to the method, through combining experience values of different boosters and tire manufacturers, the calculation result is more fit with the actual vehicle measurement result, a data basis is provided for the early design and development stage, and the verification period is shortened.
Description
Technical Field
The invention belongs to the technical field of vehicle safety, and particularly relates to a passenger car braking distance testing and calculating method.
Background
With the rapid development of automobiles, the safety problem of the vehicles becomes particularly prominent. The braking system of a vehicle plays a very important role in safe running of the vehicle, wherein "the braking distance of the vehicle" is an important index for evaluating the performance of the braking system of the vehicle.
The braking distance is an important indicator for measuring the braking performance of the automobile and is also a test item required in GB 21670. The braking distance is the performance of the whole vehicle, in the development stage of the vehicle, the braking distance engineering target is required to be decomposed into related parts, and only if each part reaches the corresponding engineering target, the braking distance target of the whole vehicle can be achieved. The method of calculating the braking distance is therefore of great importance.
The braking distance of a vehicle is not only related to the braking system performance, but also to the system idle stroke, the reaction time of the brake and booster, and the adhesion characteristics of the tires.
The existing braking distance calculation mostly adopts the empirical data of a brake, a booster and a tire, and before the whole vehicle test is carried out, the braking distance of the vehicle cannot be accurately predicted, and forward development cannot be realized.
At present, a passenger car sets a braking distance engineering target in a development stage, and whether the engineering target can be achieved or not is determined by a calculation method in a preliminary development stage besides actual car verification, so that the development scheme of parts of each braking system is defined.
Based on this, a calculation method of the braking distance is demanded.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a method for testing and calculating the braking distance of a passenger car, which can enable the braking distance of the passenger car to reach an engineering target in a vehicle development stage.
The invention is realized by the following technical scheme:
a method for testing and calculating the braking distance of a passenger car specifically comprises the following steps:
step one: giving initial parameters;
step two: calculating a braking distance in a braking coordination stage;
step three: calculating a braking distance in a braking establishment stage;
step four: calculating a braking distance in a braking maintaining stage;
step five: the total braking distance is calculated.
Further, the step of giving the initial parameters includes:
a1, setting an initial vehicle speed v 0 ；
A2, determining the operation speed of a driver;
a3, determining a master cylinder booster;
a4, determining the full-load mass of the vehicle;
a5, determining various performance values of the vehicle tire.
Further, in A2, the operation speed Vs of the driver is determined according to the force of the pedal applied by the driver.
Further, the various performance values of the vehicle tire described in A5 include the tire width H, the adhesion coefficient μ, the tire deceleration peak d M Wherein d M ＝μ*9.81。
Further, in the second step, a braking distance s in the braking coordination stage is calculated 1 ＝v 0 /3.6*t 1 Wherein t is 1 For braking coordination phase time, according to idle strokes S of different boosters 0 And the operation speed Vs of the driver.
Further, in step three, a braking distance s in the braking establishment phase is calculated 2 ＝V 0 /3.6*t 2 -d M /6*t 2 2 Wherein d M Is the peak value of the deceleration of the tyre, t 2 ＝d m /(dD/dt)d D /d t Representing the deceleration ramp-up rate; d, d D /d t ＝(V s * Pedal lever ratio) S 0 * Master cylinder area (front brake piston area pedal lever ratio brake effective radius front brake friction coefficient 2/rolling radius + rear brake piston area brake effective radius rear brake friction coefficient 2/rolling radius) 2/M.
Further, in the fourth step, the braking distance s in the braking hold stage is calculated 3 ＝((V 0 /3.6) 2 +d M 2 /4*t 2 2 -(V 0 /3.6)*d M* t 2 )/2/d m Wherein t is 3 ＝V 0 /3.6/d M -t 2 /2。
Further, in step five, total braking distance = braking distance of braking coordination phase + braking distance of braking establishment phase + braking distance of braking maintenance phase.
Compared with the prior art, the invention has the following advantages:
according to the method for testing and calculating the braking distance of the passenger car, provided by the invention, through combining experience values of different boosters and tire manufacturers, the calculation result is more fit with the actual car measurement result, so that a data basis is provided for the early design and development stage, and the verification period is shortened.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below. Like elements or portions are generally identified by like reference numerals throughout the several figures. In the drawings, elements or portions thereof are not necessarily drawn to scale.
FIG. 1 is a schematic flow chart of a method for testing and calculating a braking distance of a passenger car according to the present invention;
fig. 2 is a schematic view of the braking distance of the passenger car of the present invention.
Detailed Description
For a clear and complete description of the technical scheme and the specific working process thereof, the following specific embodiments of the invention are provided with reference to the accompanying drawings in the specification:
in the present invention, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; either directly or indirectly, through intermediaries, or both, may be in communication with each other or in interaction with each other, unless expressly defined otherwise. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.
In the present invention, unless expressly stated or limited otherwise, a first feature "up" or "down" a second feature may be the first and second features in direct contact, or the first and second features in indirect contact via an intervening medium. Moreover, a first feature being "above," "over" and "on" a second feature may be a first feature being directly above or obliquely above the second feature, or simply indicating that the first feature is level higher than the second feature. The first feature being "under", "below" and "beneath" the second feature may be the first feature being directly under or obliquely below the second feature, or simply indicating that the first feature is less level than the second feature.
In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.
Example 1
As shown in fig. 1, the present embodiment provides a method for testing and calculating a braking distance of a passenger car, where the method specifically includes the following steps:
step one: giving initial parameters;
said step-given initial parameters include:
a1, setting an initial vehicle speed v 0 ；
A2, determining the operation speed of a driver;
in A2, the operation speed Vs of the driver is determined according to the force of the pedal applied by the driver; specifically as shown in table 1;
table 1 is a table of the correspondence of the driver operating speed and the applied pedaling force
A3, determining a master cylinder booster;
a4, determining the full-load mass of the vehicle;
a5, determining various performance values of the vehicle tire;
the various performance values of the vehicle tire described in A5 include the tire width H, the adhesion coefficient mu, and the tire deceleration peak value d M Wherein d M ＝μ*9.81。
Step two: calculating a braking distance in a braking coordination stage;
calculating a braking distance s in a braking coordination phase 1 ＝v 0 /3.6*t 1 Wherein t is 1 For braking coordination phase time, according to idle strokes S of different boosters 0 And the operating speed Vs of the driver, typically an empirical value; t is t 1 Selecting from table 2, wherein the affected factors are the speed of the operation of the driver, the idle stroke of the booster of the manufacturer; forming an empirical data table 2 according to influence factors, and setting an operation rate and a booster manufacturer to select a t1 value;
table 2 brake coordination stage t 1
Step three: calculating a braking distance in a braking establishment stage;
calculating a braking distance s at a braking establishment stage 2 ＝V 0 /3.6*t 2 -d M /6*t 2 2 Wherein d M Is the peak value of the deceleration of the tyre, t 2 ＝d m /(dD/dt)；d D /d t Representing the deceleration ramp-up rate; d, d D /d t ＝(V s * Pedal lever ratio) S 0 * Master cylinder area (front brake piston area pedal lever ratio brake effective radius front brake friction coefficient 2/rolling radius + rear brake piston area brake effective radius rear brake friction coefficient 2/rolling radius) 2/M.
Step four: calculating a braking distance in a braking maintaining stage;
calculating a braking distance s in a braking hold phase 3 ＝((V 0 /3.6) 2 +d M 2 /4*
t 2 2 -(V 0 /3.6)*d M* t 2 )/2/d m Wherein t is 3 ＝V 0 /3.6/d M -t 2 /2。
Step five: calculating a total braking distance;
total braking distance = braking distance of braking coordination phase + braking distance of braking establishment phase + braking distance of braking maintenance phase.
Example 2
Taking a B70III vehicle model as an example, the embodiment provides a method for testing and calculating a braking distance of a passenger vehicle, which specifically includes the following steps:
step one: giving initial parameters;
initial speed 100km/h
Driver operation rate V s =6000N/s (fast);
pedal lever ratio: 2.7;
vacuum booster manufacturers are all the most and every, the diameter of the piston is 22.22mm, and the idle stroke S 0 ＝1.72；
The diameter of the piston of the front brake is 57.15mm, the effective radius is 120mm, and the friction coefficient is 0.39;
the diameter of the rear brake piston is 38.1mm, the effective radius is 125mm, and the friction coefficient is 0.37;
wheel rolling radius 317mm;
full load mass m=1870 kg;
the tire manufacturer is michelin with the width H=235 mm and the adhesion coefficient mu=1.035;
step two: calculating a braking distance in a braking coordination stage;
t 1 a value of 0.039s was selected from table 2;
S 1 ＝100/3.6*0.039＝1.083m；
step three: calculating a braking distance in a braking establishment stage;
t 2 ＝d M /(d D /d t ) = (μ×9.81)/((vs×pedal lever ratio) ×s 0 * Master cylinder area (front brake piston area pedal lever ratio brake effective radius front brake friction coefficient 2/rolling radius + rear brake piston area brake effective radius rear brake friction coefficient 2/rolling radius) 2/M = (1.035 x 9.81)/(6000 x 2.7) 1.72 (22.22/2) 2 *3.14*((57.17/2) 2 *3.14*2.7*120*0.39*2/317+(38.1/2) 2 *3.14*125*0.37*2/317)*2/1870)＝0.141s；
S 2 ＝V 0 /3.6*t2-d M /6*t 2 2 ＝100/3.6*0.141-1.035*9.81/6*0.141 * ＝3.
88m。
Step four: calculating a braking distance in a braking maintaining stage;
t 3 ＝V 0 /3.6/d M -t 2 /2＝100/3.6/(1.035*9.81)-0.141/2＝2.665s
S 3 ＝((V 0 /3.6) 2 +d M 2 /4*t 2 2 -(V 0 /3.6)*d M* t 2 )/2/d m ＝((100/3.6)
2 +10.16 2 /4*0.141 2 -(100/3.6)*10.16*0.141)/2/10.16＝36.055m
step five: the total braking distance is calculated.
S＝S 1 +S 2 +S 3 ＝1.083+3.88+36.055＝41.018m。
The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the specific details of the above embodiments, and various simple modifications can be made to the technical solution of the present invention within the scope of the technical concept of the present invention, and all the simple modifications belong to the protection scope of the present invention.
In addition, the specific features described in the above embodiments may be combined in any suitable manner, and in order to avoid unnecessary repetition, various possible combinations are not described further.
Moreover, any combination of the various embodiments of the invention can be made without departing from the spirit of the invention, which should also be considered as disclosed herein.
Claims (8)
1. A method for testing and calculating a braking distance of a passenger car is characterized by comprising the following steps:
step one: giving initial parameters;
step two: calculating a braking distance in a braking coordination stage;
step three: calculating a braking distance in a braking establishment stage;
step four: calculating a braking distance in a braking maintaining stage;
step five: the total braking distance is calculated.
2. A method for testing and calculating a braking distance of a passenger vehicle according to claim 1, wherein said step of giving an initial parameter comprises:
a1, setting an initial vehicle speed v 0 ；
A2, determining the operation speed of a driver;
a3, determining a master cylinder booster;
a4, determining the full-load mass of the vehicle;
a5, determining various performance values of the vehicle tire.
3. A method for testing and calculating a braking distance of a passenger vehicle according to claim 2, wherein in A2, the operation speed Vs of the driver is determined based on the force applied by the driver to step on the pedal.
4. A method for testing and calculating the braking distance of a passenger vehicle as set forth in claim 2, wherein the performance values of the vehicle tire in A5 include a tire width H, an adhesion coefficient μ, and a tire deceleration peak d M Wherein d M ＝μ*9.81。
5. The method for testing and calculating a braking distance of a passenger car according to claim 1, wherein in the second step, a braking distance s in a braking coordination stage is calculated 1 ＝v 0 /3.6*t 1 Wherein t is 1 For braking coordination phase time, according to idle strokes S of different boosters 0 And the operation speed Vs of the driver.
6. The method for testing and calculating a braking distance of a passenger car according to claim 1, wherein in the third step, a braking distance s in a braking establishment stage is calculated 2 ＝V 0 /3.6*t 2 -d M /6*t 2 2 Wherein d M Is the peak value of the deceleration of the tyre, t 2 ＝d m /(dD/dt)d D /d t Representing the deceleration ramp-up rate; d, d D /d t ＝(V s * Pedal lever ratio) S 0 * Master cylinder area (front brake piston area pedal lever ratio brake effective radius front brake friction coefficient 2/rolling radius + rear brake piston area brake effective radius rear brake friction coefficient 2/rolling radius) 2/M.
7. The method for testing and calculating a braking distance of a passenger car according to claim 1, wherein in the fourth step, a braking distance s in a braking maintaining stage is calculated 3 ＝((V 0 /3.6) 2 +d M 2 /4*t 2 2 -(V 0 /3.6)*d M* t 2 )/2/d m Wherein t is 3 ＝V 0 /3.6/d M -t 2 /2。
8. The method according to claim 1, wherein in the fifth step, the total braking distance=braking distance in the braking coordination phase+braking distance in the braking establishment phase+braking distance in the braking maintenance phase.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202310411301.2A CN116561480A (en) | 2023-04-18 | 2023-04-18 | Passenger car braking distance test and calculation method |
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| CN202310411301.2A CN116561480A (en) | 2023-04-18 | 2023-04-18 | Passenger car braking distance test and calculation method |
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