Car thesis

 Re: 2020/11
Qiche thesis vehicle maintenance economy
Introduction
40 years after China's auto industry, has made significant development, has formed a relatively complete line of automotive products and production layout . enter the WTO, China's automobile industry will be further developed, car production and ownership will continue to increase, domestic auto market share of over 95%. the car as an irreplaceable and important in modern society of transport.
attendant to questions that lead to car repair and routine maintenance to become the most public concern, the main aspects of this paper from the economy as the main vehicle maintenance, in-depth step by step to make the car better understanding of the economy. by the car principle and maintenance of the structure theory, auto repair, auto parts, maintenance charges, vehicle performance and other aspects described, combined with the main thesis.
this paper for reference during the editing process a lot of literature, reference some data data and charts, the paper is limited due to my inevitable errors and deficiencies to be corrected and went so far as to a lot of criticism.
1.
a car repair, car repair should implement the principle of
as vehicle repair Light repair the principle that the vehicle detection and diagnosis, and technical evaluation results, depending on different operating range of touch and depth, it is necessary to prevent delays in the repair vehicle condition caused by deterioration, but also to prevent wasteful repairs ahead of schedule.
The vehicle repair category < br> range of vehicle repair divided by operating the vehicle repair, assembly overhaul, minor repairs of vehicles, spare parts repair.
1, vehicles, vehicle repair
overhaul overhaul is a new car and after a certain mileage of vehicles in the exercise of (or time) , after detection and diagnosis, and technical appraisal, repair or replacement of vehicles with any part of the method, recovery vehicles, good technical condition, complete or near complete recovery of the vehicle repair restore life.
2, the total assembly overhaul
into the overhaul is the vehicle assembly after a certain mileage (or time), the use of repair or replacement of assembly and parts (including the basic parts) method, to restore its good technical condition and life restoration of repair.
3, vehicle minor repairs
minor repairs of vehicles using the method of repair and replacement parts to ensure the resumption of the operation of the vehicle the ability to work is to eliminate the main repair vehicles in operation or occurred during maintenance operations or find faults or hidden.
4, parts repair
parts repair is due to wear, deformation, damage, etc. and can not continue to use the repair parts.
three main performance requirements for vehicle maintenance
main performance requirement is power, fuel economy, car maneuverability and stability, braking the car, car ride
2. Automotive Performance
2.1
a dynamic, vehicle dynamics vehicle dynamics evaluation
a car in motion energy to achieve maximum speed, maximum acceleration and maximum climbing ability, the basic use of the car performance. Qiju an efficient means of transport, transport efficiency depends largely on the level of vehicle dynamics. This is because the vehicle driving The higher the speed, the average technology, the higher productivity of automobile transportation. And the average technology of the most important factor is the speed of vehicle dynamics. With the growth of China's highway mileage, highway traffic and automotive performance improvement, driving speed rising, but in the car with the use of extension of time will gradually decrease its power, can not achieve the requirements of high speed, so not only reduces the efficiency of the automobile and road transport should be proper capacity, and a traffic accident , the potential for blocking traffic. Therefore, the Ministry of Communications Decree No. 13 issued in 1990, in particular, require regular testing of vehicle dynamics. vehicle inspection department of motor vehicles commonly used maximum speed, acceleration, maximum climbing angle, engine maximum output power, the chassis as a power output of the maximum drive power index
1. maximum speed (km / h)
maximum speed of the motor vehicle is determined to plant the largest state in the total mass of wind l3m / s conditions, the dry, clean, flat concrete or asphalt, to the highest stable speed.
acceleration t (s) vehicle acceleration capability means the car is moving rapidly to increase the capacity of speed. usually car acceleration time to evaluate.
2.
acceleration time is the acceleration time of a car factory set to the maximum total mass of the state in the wind l3m / s under the conditions of a dry, clean, flat concrete or asphalt, by a to a high-speed low-speed acceleration of the time required.
(1) standing start acceleration time to accelerate the shift start time, the means provided for low-end starting with the fastest acceleration (including the selection of the appropriate shift time) gradually After changing to the most upscale and accelerate the speed to a specified time is required, the speed of its provisions in different countries, such as 0-50 km / h, on the cars used 0-80 km / h ,0-100 km / h, or starting with the provision of low-grade to the maximum acceleration and gradually change to the most high-end, the time required to reach a certain distance, which is generally prescribed distance 0-400m ,0-800m ,0-100Om, start acceleration time is shorter, more dynamic good;
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(2) also known as direct file overtaking acceleration time to accelerate the time or times that the most high-end high-end, from a predetermined starting speed, to accelerate to a speed the time required for overtaking acceleration shorter, the better the performance of its high speed. overtaking acceleration of the car does not specify, overhauled the car with the speed limiting device to direct traffic load files from the muzzle velocity of 20km / h speeds up to 40km / h acceleration time, should meet the requirements.
3. the largest climbing degree Imax (%)
is the largest degree of a car full of climbing, in a good concrete or asphalt pavement on the ramp, cars with the lowest forward gear to climb a maximum gradient. Due to the ramp road conditions, vehicle comprehensive performance inspection stations typically do not do Qiche climbing test.
4. engine maximum output power Pmax
engine maximum output power of an engine at full load, only with the maintenance accessories necessary for operation when the power output, also known as total power. At this point the engine being tested is generally not with the air filter, cooling fan and other accessories. The new factory engine maximum output power generally refers to the engine power rating. Rated Power is the specific purpose of the engine manufacturer, engine under full load and rated speed under the total power. In some foreign manufacturers is the so-called engine rated power at rated speed net power output. often rated power marked after the word after a certain period, the state of technology changes, the maximum output power of the engine becomes smaller, so the smaller the difference with its evaluation of the extent of the drop in engine technology. car engine maximum output power is small compared with the rated power at 75%, technical condition of the car as the three levels. So the size of the engine maximum output power used as a car before and after and maintenance before and after the evaluation of dynamic indicators are reasonable, it should be noted, in the car with a comprehensive performance test station No external load dynamometer or chassis dynamometer method of the determination of engine power, must be converted before the total power compared with the rated power.
5. chassis output maximum output drive power Dpmax
chassis is the maximum drive power driving the car when using direct file, the maximum wheel drive power output (corresponding to the engine speed near rated speed). chassis maximum drive power output maximum power output generally referred to as the chassis is the actual ability to overcome the greatest resistance to the vehicle, a car power Evaluation is an important indicator. car use, the engine itself, engine accessories and the technical condition of transmission lines will
decreased, the chassis, the maximum output power will therefore decrease.
2.2 fuel economy < br> First, the fuel economy rating
vehicle fuel economy is an important performance car, but also has a car for each one of the indicators are most concerned about.
comments world vehicle fuel economy, general use fuel consumption or oil trip to represent. fuel consumption is the motor vehicle mileage fully loaded unit volume of fuel required. China and Europe by driving a few hundred kilometers of fuel consumption (L) to indicate that L/100km; oil stroke is the motor vehicle fully loaded, can unit volume of fuel mileage, the United States is to use a gallon of fuel mileage can be expressed in the former representation, with smaller values, the better the fuel economy; the latter representation , the greater the value, the better fuel economy. vehicle fuel economy indicators and characteristics of the engine and car weight, speed and resistance to all kinds of sports such as air drag, rolling resistance and the resistance of the size and climbing efficiency and transmission reduction ratio and others have, and so, often in the numerical difference between the actual situation.
vehicle fuel economy indicator by the amount of that performance in the important automotive performance. In particular, China must implement the fuel tax, motor vehicle parameters of the fuel consumption had special significance. fuel consumption parameters of these indicators in our car manufacturers in accordance with state testing standards, through the kind of car was out of the test. It includes the constant cycle fuel consumption and fuel consumption per hundred kilometers. < br> automobile fuel economy, there are two measurement methods: one driving test, the other is on the road in the flat and constant speed under certain conditions, fuel consumption test.
flat car in no way the constant velocity gradient constant fuel consumption when driving for the fuel consumption per hundred kilometers. but also included the so-called constant speed constant driving in different situations. different constant speed driving, fuel consumption per hundred kilometers is different. select a flat cement surface without slope or asphalt pavement, cars were different in the most high-end speed (which can be every 10km / h speed to take a point) constant driving finish this journey, round trip averaged (to eliminate wind and slope effects), write down fuel consumption, can be obtained under different speed car fuel consumption per hundred kilometers, the so-called isokinetic hundred kilometers.
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the constant speed fuel consumption and the actual driving conditions are very different, in fact, can not fully assess the fuel economy of vehicles now generally used to evaluate the cycle fuel consumption of motor vehicles fuel economy. cycle fuel consumption is typically specified in a section of the motor vehicles in different working conditions set by the fuel consumption when driving, at least to require the constant velocity, acceleration and deceleration 3 conditions, the complex also included the suspension of service and other starting and idling conditions, and then converted into fuel consumption per hundred kilometers. In general, obtained also with the constant cycle of fuel consumption per hundred kilometers (specify speed) the weighted average fuel consumption achieved combined consumption to more scientific evaluation of the car fuel economy.
but sometimes not strictly call this combined consumption cycle fuel consumption, so the city gives the fuel consumption of modern cars and highways fuel consumption, fuel consumption should be the city's comprehensive and highway combined consumption, but also referred to as circulating oil through the city and highway cycle fuel consumption, fuel consumption in our city and highway fuel consumption is called. For the evaluation of vehicle fuel economy, vehicle fuel consumption by the general test to determine, it is to assess the situation in the use and maintenance of automotive technology and comprehensive quality parameters, but also automotive fault diagnosis and analysis of an important reference. testing vehicle fuel consumption, fuel consumption test often measured by fuel consumption to the volume or quality, said the current
The car engine is high-speed gasoline engines, the higher the thermal efficiency of the engine the higher fuel efficiency, the more fuel-efficient. And the thermal efficiency of the engine compression ratio with the increase of passenger car gasoline engine compression ratio is usually in the 9.3-10.5 s room. At the same time, the system also uses variable valve device (variable valve lift, variable camshaft angle, variable-length intake manifold, etc.) and lean techniques to achieve the purpose of fuel economy.
the same time, the world Many large auto manufacturers are actively developing and promoting diesel engine, gasoline engine the vehicle diesel engine is easier to achieve further savings in fuel purposes. As technology advances, the current diesel engine vibration, noise, unit mass (Weight) area and reduce gasoline the gap, but the power is still relatively small. than a decade ago was the petrol and diesel golf golf in the same environment, comparative testing, 1.6-liter diesel engine equipped golf cars, the maximum speed of 145 km, average fuel consumption per hundred kilometers City 6.8 liters, 5.3 liters highway; assembled 1.3-liter gasoline engine golf cars, the maximum speed of 160 km, average fuel consumption per hundred kilometers city of 10 liters, 6.7 liters road. As flat engine load change, with significant fuel economy than gasoline capacity.
engine power and load rate on fuel economy has a great influence. general engine cylinder displacement depends on the output power, according to the actual needs of the user a reasonable choice auto emission, in the car keep moving higher power efficiency, improving vehicle fuel economy makes sense. If the vehicle is often used in the city, not more than 80 kilometers per hour, select the 1.6-liter small-displacement cars below is appropriate.
transmission system on the car vehicle fuel economy have a major impact. derailleur gear more, not only Qiche shift smoothly and the engine of economic conditions in the operation increased the opportunity to help improve fuel economy. so modern cars tend to be 5 files or more transmission, or use of infinitely variable to ensure that under any conditions with the engine of economic conditions in the most likely to work. In the case of constant speed, joining high gear, the transmission ratio is small, the engine speed is low; bonding low gear, the transmission ratio, the corresponding engine speed high. known by the engine load characteristics, the same when the engine load, speed is generally the lower the fuel consumption rate decreases. in certain driving conditions, the transmission speed ratio the more Small, higher automobile fuel economy, thus driving the car in high-end digital economy. to the road in good condition at a higher speed limits, car transmission to install in less than 1 overdrive ratio, in the same speed cases, hanging overdrive allows the engine speed is relatively low, the relative fuel consumption is also reduced.
transmission system includes transmission of the file transmission ratio and final drive ratio than in the good roads for a small speed Main gear ratio can improve vehicle fuel economy. However, many objects in the car has a The dynamic is too low, so they will deteriorate the fuel economy of cars, so the general design has a range of gear transmission ratio, making the files directly linked to back-up power when there are still large for the acceleration or the Xiao-Po. < br> As Hyundai increased the speed of the car's styling is also on the fuel economy have important implications, the faster the greater the impact speed, which is commonly known as area and the air resistance coefficient to achieve, in general, depends on vehicle frontal area size, air resistance depends on body shape. To this end, compactness and sleek car body is the way to improve fuel economy. At present, many cars, air resistance coefficient In the 0.28-0.3 about the reduction of fuel consumption played a significant role. Generally speaking, body height more than 1.5 meters of cars, the air drag coefficient is relatively large, with the same type of lower body power systems Compared with cars, not only speed reduced, and fuel consumption also increases. Thus, space, speed, fuel consumption is a combination of conflict, can only seek a reasonable balance, there can be no exhaustive two car
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, fuel economy factors
we all know, all kinds of vehicle fuel economy is different, affecting the automobile fuel economy is an important factor in engine performance, but there are other factors, including the vehicle structure, driving skills and and other road conditions.
are currently high domestic gasoline engine car engine, the higher the thermal efficiency of the engine the higher fuel efficiency, the more fuel-efficient. And the thermal efficiency of the engine compression ratio increases with the increase in gasoline cars now engine compression ratio is generally between 9.3-10.5. Meanwhile, the system also uses variable valve device (variable valve lift, variable camshaft angle, variable-length intake manifold, etc.) and lean techniques to achieve the fuel economy purpose.
increase the speed of the modern automobile, car styling on fuel economy also have important implications, the faster the greater the impact speed, which is commonly known as vehicle frontal area and air resistance coefficient to achieve, in general, depends on vehicle frontal area size, air resistance depends on body shape. To this end, compactness and sleek car body is the way to improve fuel economy. At present, many cars air resistance coefficient of about 0.28-0.3, and has played a significant role in reducing fuel consumption.
above, affect vehicle fuel economy in many ways. For the new car is concerned, it is not only related to the engine, but also to the transmission, final drive, car weight, body shape and other factors. Therefore, the vehicle fuel economy is a combination of factors brings together the technical indicators, it can only reflect the operating cost, can not represent the pros and cons of the car, the consumption Vehicle Differential oil does not indicate high, low fuel consumption is not that Qiche good, because the merits of the car and the car has safety, comfort, whereas the fuel economy of these properties are often associated with the conflict between the.
2.3 system
a dynamic performance, braking distance, braking distance is
the driver began to depress the brake pedal from play until the parking brake, cars driving distance. affect the braking distance of factors, primarily system moving coordinate system the length of time, adhesion of the size of the maximum braking force and braking the brake start speed. so reduce the need to shorten the braking distance braking system coordination of time, increasing the maximum braking force the brake and road adhesion coefficient. < br> In the case of high-speed form, cars have greater kinetic energy, long duration of the brake, the brake temperature is higher braking performance degradation, thus increasing the length of the brake non-secure area. To do this in the road when brake should be used cautiously. According to the operation of traffic flow, there is predictability to the brake. prohibited in the larger flow, vehicle gap is relatively small cases, sudden braking. Although slowed down the parking brake performance, but to follow the car large non-secure areas braking, and rear-end collision may trigger a major multi-car accident
Second, deviation and sideslip
automobile brake during braking, due to range around the wheel braking force, vehicle can not maintain the original direction of travel, resulting itself left or right side drive, or even out of control, can easily cause traffic accidents. most of the deviation is due to a car wheel brakes. adjustments caused by improper assembly, in order to prevent or eliminate deviation caused by a serious collision, the brake must be rigorous testing and found that sub-standard and timely repair or re-adjusted to the traffic safety policy.
car when braking, rear brakes locking, while the front wheel no rear braking force or relatively small car will be along the cross slope, slope direction of sliding; if the first locking front and rear than the duration of the interval of 0.5 seconds, sliding rear serious; rear No braking force, front-wheel or front wheel than the rear brake before locking locking, auto basic straight-line driving, the performance of good stability. In order to prevent skidding rear axle, no special device for wheel brake the car, adjusting the brake, front and rear axles of the wheels should be at the same time locking. When sliding, you should immediately stop braking (especially at high speed), ease the throttle and the steering wheel toward the rear sliding direction of rotation, When the car's position is adjusted, then the steering wheel to smooth the normal driving routes.
braking skid brake system only through the improvement of the structural design can be completely resolved. the current assembly of the ABS anti-lock braking system can solve this problem.
braking force of the size of the braking distance of the car has a lot to the left and right wheel braking force of brake performance. test brake system requires a special braking force test bed. II-like requirements before the rear axle braking force difference between left and right wheels, respectively, of the shaft load is not greater than 5% to 8% is appropriate.
Third, coordination of time
brake system Brake System Coordination time is depress the brake pedal to the emergence of the braking force and braking force through the time and the growth of time, depending on the structure of automotive brake systems and technical conditions. To ensure the safety of car driving, braking system shall be as short as possible Coordination of time.
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2.4 vehicle handling and stability
one, handling and stability of the meaning of
cars can drive by the driver steering, resistance to change direction in the figure outside interference, to maintain certain speed, the driver will not cause excessive stress and fatigue, stable driving, the car's handling and stability as this ability. vehicle handling and stability and is directly related to traffic safety, poor vehicle handling and stability is difficult to control, serious cases may spin or rollover, causing traffic accidents. So, good handling and stability is important to ensure traffic safety. vehicle handling and stability characteristics of available Stable Steering, car and driver stability limit - Automotive Systems in an emergency handling and stability as the evaluation index
Second, handling and stability of the evaluation index
Stable Steering evaluation of vehicle handling and stability characteristics are important indicators. stable steering characteristics, there are three conditions: understeer, oversteer and neutral steering. drivers are accustomed to driving cars with moderate understeer. Therefore, the design, the general must have the appropriate amount of understeer, to ensure that even when the car suddenly appeared good flick driving performance. To ensure that in normal driving condition car with good handling and stability, but also required the response of the steering wheel angle input to be sensitive, straight sex, and back to the positive good, steering is easy to operate, etc..
steering vehicle the stability of the limit when a great impact on safe driving. If the driver control the car motion state action to make the car more than this limit, the car's movement will lose its stability, spin or rollover, thereby endangering the traffic safety .
the current round of anti-lateral force on the attachment limit is reached first, because the front wheel slip occurs, reduce the car's yaw rate, steering radius, cars will be thrown outside, the occurrence of yaw Drift , suspension and steering device structure and parameters;
2. car use factors, such as centrifugal force, the car great handling and stability.
addition, you should pay attention to speed on the vehicle driving stability injury. speed, the car was understeer, but in high speed, the car may become over-turn. So in high-speed driving, be sure to pay attention to the manipulation of the steering wheel, to avoid excessive centrifugal force, to ensure high-speed traffic safety Automobile ride
2.5 Automobile ride
evaluation methods, usually based on the human body's physiological response to vibration and impact in maintaining the integrity of the formulation of the goods, and with the vibration of the physical quantities, such as frequency, amplitude, acceleration, such as the rate of change of acceleration
ride comfort evaluation index.
currently used natural frequency of vibration of car body acceleration and vibration ride comfort evaluation of the car. results show that, in order to keep the car with good ride comfort , the natural frequency of vibration of the body should be accustomed to walking the human body, the body, the lower the frequency of movement. It is about 60 ~ 85 times / min (1HZ ~ 1.6HZ), vibration acceleration limit is 0.2 ~ 0.3g. To ensure that the integrity of cargo, the body acceleration and it is not too large. If the body acceleration of 1g, the goods have not been fixed may leave the compartment floor. Therefore, the body vibration acceleration limit should be less than 0.6 ~ 0.7g.
one, ride comfort index
rms acceleration is given by the human body in the 1 ~ 80Hz frequency response range of the vibration limits of three different feeling: comfortable - lower limits, fatigue - ergonomic lower limit and the exposure limit.
comfortable - lower limit and remain comfortable about. In this limit, the human body vibration exposure on the subjective feeling well and the successful completion of eating, reading, writing and other activities.
fatigue - Ergonomics reduce the efficiency of the boundaries and keep working. When the pilot to withstand vibration within this limit when driving to maintain the normal manner.
exposure limit is usually the body can withstand vibration, as the upper limit. When the human body to withstand the vibration intensity at this limit within the health or safety will be maintained.
three boundaries to allow the value of vibration acceleration is different. - lower limit vibration) longer, feeling down acceleration permitted limits. Therefore, the available exposure time to reach a certain threshold allows to measure the strength of the human body the size of the vibration sense. the body most sensitive frequency range, the vertical vibration is 4 ~ 8Hz; The level of vibration is 1 ~ 2Hz or less. In 2.8Hz less, the same exposure time, lower than the allowable value of vibration acceleration level of vertical vibration. frequency of 2.8Hz over the opposite.
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II riding comfort of vehicles of structural factors
order to facilitate the analysis, the need for an automobile by a number of quality vibration system can be simplified. vibration in the study, often by the equivalent system in place of the car that the car is linked to each other as the suspension by the quality and composed of non-suspended mass.
vehicle sprung mass by the body, frame and the assembly of the composition. The quality of the horizontal axis Y through the center of mass moment of inertia is, the sprung mass by the shock absorber and suspension spring and axles, wheels. wheels, axles constitute the quality of the non-suspension, wheels and then after a certain elasticity and damping of the tires on the road support.
suspension structure, tires, suspension and non suspension quality is the quality of ride comfort important because
suspension structure mainly refers to the elastic element, guiding device and the damping device, in which elastic damping suspension system components and a greater impact.
elastic element as the car body to make a flexible suspension vibration of single degree of freedom to reduce suspension stiffness can reduce the body's natural frequency. When the car when the other structural parameters constant, to make the suspension system has a low natural frequency of suspension must have a lot of static deflection. It is Qiche full load, the stiffness of the suspension in the same amount of deformation under static load. of variable stiffness suspension, the static deflection is loaded by motor vehicles, the suspension system and the corresponding static load and to determine the instantaneous stiffness.
In order to prevent cars driving on uneven road often shock buffer block, there should be enough suspension deflection (refer to the position of equilibrium to the suspension and suspension frame touching the deformation).
front and rear suspension dynamic deflection constant static deflection under the corresponding selection model and its value depends on regular use of the road conditions, trucks off-road vehicles may limit the scope to take in order to reduce the wheel and suspension breakdown vacant.
For both large static deflection suspension without affecting the other performance indicators, can take some measures, such as variable stiffness suspension using nonlinear suspension. because of nonlinear suspension stiffness increases with the dynamic travel to move in the same trip, be more dynamic than the linear suspension capacity (refer to the time of suspension from the position of static load, the deformation of the contact with the frame part of the maximum deformation). Suspension of action The greater capacity of the buffer the less likely the impact block. modern truck leaf spring rear suspension on the use of such increases is the Vice-reed the easiest way. In order to load changes, the static deflection remains unchanged, Ideally set in the suspension automatically adjusts the ride height of the device.
curve with variable stiffness suspension, the load change in terms of large trucks, will significantly improve the ride comfort. For example, a truck at full load, the load after the suspension was about 4 times more than empty, assuming suspension stiffness constant, if the static deflection at full load is equal to 100mm, then the empty car of the static deflection will be less than 25mm. is not difficult calculated, fully loaded, the vibration frequency of 1.6Hz, the frequency of the empty car was 3.2Hz. Clearly, the empty car's vibration frequency is too high, ride comfort is poor. If the suspension with variable stiffness, so that the empty car lower stiffness than the full load, will reduce the vibration frequency of the empty vehicle to improve vehicle ride comfort.
in the suspension system, damping vibration attenuation caused by many sources. For example, in a relative motion of the friction pairs , tire deformation, friction between the rubber molecules, or other shock absorber in the system design. For a variety of suspension structure to leaf spring suspension system, the largest dry friction, the greater the number of leaf spring leaves, the greater the friction. So Some cars adopted a leaf spring suspension, you can not put damper, but the value of the damping force is very unstable, rusty steel plate after the resistance is too large and difficult to control. And with the flexibility of the other components of internal friction is small (such as single leaf springs, coil springs, torsion bar springs, etc.) of the suspension, you must use the damper to absorb vibration energy, that vibration is quickly fading.
dry friction suspension system allows the flexibility of suspension components part or artificially locked, making the car vibrate only in the tires, thus increasing the vibration frequency, and so easy to pass on the impact of the body surface. Therefore, to reduce friction between the leaf spring blade should reduce the number of pieces; properly calculated The pieces in the free state radius of curvature for each of the pieces cut into trapezoidal or semi-circular ends to ensure that the contact pressure distribution between segments; in the film grease or friction between the liner and other methods to reduce friction
tire ride comfort on the impact depends on the tire radial stiffness, capacity and flattening the tire inside the tire damping effect caused by friction. reducing tire radial stiffness, can suspension stiffness conversion reduced by 10% to 15% . When the car driving on rough roads, due to the elasticity of the tire, the tire cross-section contour displacement curve to smooth over smooth roads, rocky road of its length than the actual length of at large, the height of the curve when compared with the actual height of the small rough road , the so-called flattening the tires ability. It allows the car's resonance frequency vibration reduction.
order to improve vehicle ride comfort, tire radial stiffness should be reduced as much as possible. in the use of adequate soft suspension cases, a large speed range, the possibility of low-frequency resonance can be eliminated completely. But tire stiffness is too low, will increase the lateral deviation from the wheel, affecting the stability, while also increasing the rolling resistance, reduce tire life .
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followed by reducing unsprung mass, the relative high frequency vibration will cause increased damping (), and thus reduce the energy absorbed by shock absorber, working conditions can be improved. non-suspended mass can be due to Suspension type of change-oriented devices, the use of independent suspension, can reduce the non-suspended mass.
commonly used non-suspended mass and the suspended mass ratio of the evaluation of non suspended mass impact on ride comfort. the ratio of the smaller ride the better. For modern cars = 10.5 ~ 14.5%, to ensure good ride comfort.
In short, the impact of the structural parameters of ride comfort a lot, and the relations are complicated, we must conduct a comprehensive analysis of these parameters in order to correct Choose parameters and improving the ride comfort of vehicles running.
seat comfort to a great extent depends on the structure, size, layout and body (or the truck's cab) and sealing (dust, rain, to prevent the exhaust gas into the body) ...