汽車制動器設(shè)計(jì)【盤式制動器】
汽車制動器設(shè)計(jì)【盤式制動器】,盤式制動器,汽車制動器設(shè)計(jì)【盤式制動器】,汽車,制動器,設(shè)計(jì)
河南理工大學(xué)萬方科技學(xué)院
本科畢業(yè)設(shè)計(jì)(論文)中期檢查表
指導(dǎo)教師: 趙凱輝 職稱: 副教授
所在院(系): 機(jī)械車輛工程系
題 目
盤式制動器設(shè)計(jì)
學(xué)生姓名
胡歡歡
專業(yè)班級
機(jī)制四班
學(xué)號
0828070187
一、選題質(zhì)量:(主要從以下四個(gè)方面填寫:1、選題是否符合專業(yè)培養(yǎng)目標(biāo),能否體現(xiàn)綜合訓(xùn)練要求;2、題目難易程度;3、題目工作量;4、題目與生產(chǎn)、科研、經(jīng)濟(jì)、社會、文化及實(shí)驗(yàn)室建設(shè)等實(shí)際的結(jié)合程度)
此次畢業(yè)設(shè)計(jì)題目符合專業(yè)培養(yǎng)目標(biāo),從本次設(shè)計(jì)中能夠體現(xiàn)四年來的學(xué)習(xí)情況,能夠達(dá)到綜合訓(xùn)練要求;此次所選的題目難易適中,既能體現(xiàn)自己對于以往學(xué)習(xí)知識的掌握情況,又能在設(shè)計(jì)中發(fā)現(xiàn)新的問題,學(xué)到新的知識,提高自己的綜合能力;設(shè)計(jì)的工作量比較大的,這使我能充分利用時(shí)間,過的充實(shí);此次選題是綜合了生產(chǎn)、科研、經(jīng)濟(jì)、社會、文化及實(shí)驗(yàn)室建設(shè)等方面所選的結(jié)果,不僅能鞏固自己的知識,還能培養(yǎng)對于社會現(xiàn)階段制動器改良方面的見解,提高自己的綜合能力
二、開題報(bào)告完成情況:
本人查找了充足的資料文獻(xiàn)并上網(wǎng)了解了現(xiàn)階段制動器的發(fā)展?fàn)顩r,
從自己的了解中制定了開題報(bào)告,已在四月份完成開題報(bào)告的制作。
三、階段性成果:
從實(shí)際學(xué)習(xí)出發(fā),查詢并學(xué)習(xí)了制動機(jī)設(shè)計(jì)相關(guān)的書目,對于制
動器設(shè)計(jì)有了較為深刻的了解,綜合各方面因素制定了自己設(shè)計(jì)的方向,
從而制定了自己的設(shè)計(jì)計(jì)劃,并且已經(jīng)完成了部分計(jì)劃。
四、存在主要問題:
本人完成論文階段存在些問題,對于重點(diǎn)部分內(nèi)容拓展的不夠,布
局需要調(diào)整,在適當(dāng)板塊應(yīng)該適當(dāng)采用三級標(biāo)題,使內(nèi)用看起來簡單明朗
五、指導(dǎo)教師對學(xué)生在畢業(yè)實(shí)習(xí)中,勞動、學(xué)習(xí)紀(jì)律及畢業(yè)設(shè)計(jì)(論文)進(jìn)展等方面的評語
指導(dǎo)教師: (簽名)
年 月 日
附件
外國文獻(xiàn)
HYDRAULIC BRAKE BASICS
Air?brakes?get more attention, but?hydraulic?brakes?are installed on more vehicles.?Understanding how they work is the first step to safe, cost-effective diagnosis and repair.
Ever wonder why there can't be just one kind of?brake??It's because air and?hydraulic?brakes?each have operating characteristics that make one or the other ideal for certain applications.
In heavy-duty combination vehicles, air is the clear choice because of the large volume of liquid that would be needed to acadia all the wheel cylinders.?Plus, dealing with gladhands and hoses filled with?hydraulic?fluid would be messy.
But for light and medium-duty straight-truck applications,?hydraulic?brakes?offer advantages including:
· Brake?feel — that is, as the pedal is pressed farther down, effort increases;
· High line pressures, which permit the use of lighter, more compact braking components;
· Less initial expense, due to smaller and fewer components;
· Cleanliness —?hydraulic?brakes?are closed systems;
· Ease of locating leaks, since fluid is visible.
There are many more permutations of?hydraulic?brake?systems than found in air systems, but all have basic similarities.
THE HYDRAULIC SYSTEM
All hydraulic brake systems contain a fluid reservoir, a master cylinder, which produces?hydraulic?pressure,?hydraulic?lines and hoses to carry pressurized fluid to the brakes, and one or more wheel cylinder(s) on each wheel.
The wheel cylinders expand under fluid pressure, and force the?brake?shoes against the insides of the drums.?If disc?brakes?are used, calipers, with integral cylinders, clamp down on the rotors when pressure is applied.
Because a vehicle must be able to stop much more quickly than it can accelerate, a tremendous amount of braking force is needed.?Therefore, the retarding horsepower generated by the?brakes?must be several times that of the engine.
In order to develop the forces required to hold the?brake?linings against the drums or discs, and to achieve controlled deceleration, it is necessary to multiply the original force applied at the?brake?pedal.
When a?hydraulic?system is used, the only mechanical leverage is in the foot pedal linkage.?However, varying the diameter of the wheel cylinders or caliper diameters, in relation to the master cylinder bore diameter, provides an additional increase in ratio.
In a?hydraulic?system, the pressure delivered by the various wheel cylinders is directly affected by the areas of their pistons.?For example, if one wheel-cylinder piston has an area of 2 square inches, and another piston has an area of 1 square inch, and the system pressure is 400 psi, the 2-square-inch piston will push against the brake?shoes with a force of 800 pounds. The 1-square-inch piston will exert a force of 400 pounds.?The ratio between the areas of the master cylinder and the wheel cylinders determine the multiplication of force at the wheel cylinder pistons.
Keep in mind that the larger a wheel cylinder's diameter, the more fluid must be supplied by the master cylinder to fill it.?This translates into a longer master-cylinder stroke.
If the master cylinder bore diameter is increased and the applying force remains the same, less pressure will be developed in the system, but a larger wheel-cylinder piston can be used to achieve the desired pressure at the wheel cylinder.?Obviously, a replacement master cylinder, wheel cylinder or caliper must be of the same design and bore as the original unit.
Hydraulic?brake?systems are split systems, comprising two discreet braking circuits.?One master-cylinder piston and reservoir is used to actuate the?brakes?on one axle, with a separate piston and reservoir actuating the?brakes?on the other axle(s).?Although rare, some light-duty brake systems are split diagonally rather than axle by axle.
The reason for the split system is that if a leak develops in one?hydraulic?circuit, the other will stop the vehicle.?Of course, the vehicle shouldn't be driven any farther than necessary to have the?brake?system repaired.
When one of the?hydraulic?circuits fails, a pressure -differential switch senses unequal pressure between the two circuits.?The switch contains a piston located by a centering spring and electrical contacts at each end.?Fluid pressure from one?hydraulic?circuit is supplied to one end of the pressure
-differential switch, and pressure from the other circuit is supplied to the other end.?As pressure falls in one circuit, the other circuit's normal pressure forces the piston to the inoperative side, closing the contacts and illuminating a dashboard warning light.
POWER ASSIST
Power assist units, or boosters, reduce operator effort at the?brake?pedal.?Vacuum boosters, popular on light-duty vehicles, make use of an engine vacuum on one side of a diaphragm, and atmospheric pressure on the other side.?A valve allows the vacuum to act on the diaphragm in proportion to?brake?pedal travel.?This assists the pedal effort, and allows increased pressure on the?brake?fluid, without an undue increase in pedal effort.
Other types of boosters use?hydraulic?pressure — either from the vehicle's power steering pump or from a separate electric pump, or both — to assist pedal effort. As the?brake?pedal is depressed, a valve increases?hydraulic?pressure in a boost chamber to apply increased pressure to the master cylinder pistons.
Some systems use both vacuum and?hydraulic?assist.?In other systems, air pressure from an onboard compressor is used to generate?hydraulic?system pressure.
VALVING
Valves commonly found in?hydraulic?brake?systems include: Proportioning, or pressure-balance valves.?These restrict a percentage of?hydraulic?pressure to the rear?brakes?when system pressure reaches a preset high value. This improves front/rear?brake?balance during high-speed braking, when some of a vehicle's rear weight is transferred forward, and helps prevent rear-wheel lockup. Some proportioning valves are height-sensing.?That is, they adjust rear-brake?pressure in response to vehicle load.?As a vehicle's load increases (decreasing height) more?hydraulic?pressure to the rear?brakes?is allowed; Metering valves.?These hold off pressure to front disc?brakes?to allow rear drum?brake?shoes to overcome return-spring pressure and make contact with the rear drums.?This prevents locking the front?brakes?on slippery surfaces under light braking applications.?These valves do not come into play during hard braking.
PARKING
The parking function varies greatly among?hydraulic?brake?systems.?Many light-duty vehicles with rear drum?brakes?use a passenger-car type lever-and-cable setup. A ratcheted lever or foot pedal pulls a cable, which, in turn, pulls a lever assembly at each rear wheel end.?The lever forces the?brake?shoes apart, and they are mechanically held against the drums until the ratchet is released.
Other parking systems include spring chambers, like those used on air-brake?systems.?These are spring-engaged, but are disengaged by?hydraulic?pressure instead of air.
ANTILOCK
On many hydraulically braked light-duty trucks, antilock?brakes?are used on the rear wheels to preserve braking stability when these vehicles are lightly loaded.?Front and rear-wheel antilock is usually an option, except for vehicles over 10,000 pounds GVWR, which are required to have steer and drive-axle antilock.
In current?hydraulic?antilock systems, a dump valve releases pressurized?hydraulic?fluid into an accumulator in the event of an impending wheel lockup.
An electronic control box receives speed signal(s) from sensors in the transmission and/or at the wheels.?When the?brakes?are applied, the control box senses the decrease in rear wheel speed, and activates the dump valve(s) if the rate of deceleration exceeds a predetermined limit.
The control box energizes the dump valve with a series of rapid pulses to bleed-off wheel?hydraulic?pressure.?Continuing in antilock mode, the dump valve is pulsed to keep the wheels rotating, while maintaining controlled deceleration.
At the end of such a stop, the valve de-energizes and any fluid in the accumulator is returned to the master cylinder.?Normal?brake?operation resumes.
FOUNDATION BRAKES
Foundation?brakes?in?hydraulic?systems can be either drum or disc.?In many applications, discs are used on the front axle and drums on the rear.
Drum?brakes?are said to be self-energizing.?That's because when the?brake?shoes expand and contact a rotating drum, the leading, or forward,?brake?shoe is pushed against the trailing shoe by the force of the moving drum.?This results in higher lining-to-drum pressure than would be produced by the wheel cylinder alone.
As?brake?linings wear, the shoes periodically must be moved closer to the drums to ensure proper contact during braking.?While some older drum?brake?assemblies are manually adjusted, most are automatic.?These use a star wheel or ratchet assembly, which senses when the wheel cylinder has traveled beyond its normal stroke, and expands the pivot point at the other end of the?brake?shoes.
In addition to being one of the friction elements, the?brake?drum or rotor also acts as a heat sink.?It must rapidly absorb heat during braking, and hold it until it can be dissipated into the air.?The heavier a drum or rotor is, the more heat it can hold.
This is important, since the hotter the?brake?linings get, the more susceptible they are to heat fade.?Heat fade is induced by repeated hard stops and results in reduced lining-to-drum/rotor friction and increased vehicle stopping distance.?As a rule, high-quality linings will display less heat fade than inferior ones.?Also, discbrakes?are far more resistant to heat fade than drum?brakes.
Another type of fade that?brakes?are susceptible to is water fade.?Drum?brakes, with their large surface areas, apply fewer pounds per square inch of force between lining and drum during a stop than disc?brakes.?This, added to the drum's water-retaining shape, promotes hydroplaning between shoe and drum under wet conditions.?The result is greatly increased stopping distance.
Disc?brakes, with their smaller friction surfaces and high clamping forces, do a good job of wiping water from rotors, and display little reduction in stopping capability when wet.
中文翻譯
液壓制動基礎(chǔ)
空氣制動系統(tǒng)得到更多的關(guān)注,但更多的車輛上安裝液壓制動器。了解它們是如何工作的,是安全,具成本效益的診斷和修復(fù)的第一步。
有沒有想過為什么不能只是其中的一種制動?這是因?yàn)榭諝夂鸵簤褐苿悠?,使一個(gè)或某些應(yīng)用程序的其他理想的經(jīng)營特色。重型組合的車輛,空氣是明確的選擇,因?yàn)閷⑿枰罅康囊后w阿卡迪亞所有分泵。此外,充滿液壓油與制動分泵和軟管的將是混亂的。但對于輕型和中型卡車直應(yīng)用,液壓制動器提供的優(yōu)勢包括:
?制動感覺 - 那就是,踏板越往下壓,努力增加;高線壓力,允許使用更輕,更緊湊的制動組件;
?更少的初始費(fèi)用,由于用更小和更少的元件;
?衛(wèi)生,液壓制動器是封閉的系統(tǒng);
?易于定位泄漏,因?yàn)橐后w是可見的。液壓制動系統(tǒng)有更多的排列,比在空氣系統(tǒng)中發(fā)現(xiàn),但都基本相似。
液壓系統(tǒng)
所有的液壓制動系統(tǒng)包含流體水庫,主缸,液壓,液壓管路,對制動器進(jìn)行加壓流體的軟管和一個(gè)或多個(gè)輪缸(S)對每個(gè)車輪產(chǎn)生。分泵擴(kuò)大流體壓力下,迫使制動蹄對鼓的內(nèi)側(cè)。如果使用盤式制動器,卡鉗與不可分割的氣瓶打擊轉(zhuǎn)子時(shí)施加壓力。
因?yàn)檐囕v必須能夠更迅速,它可以加速到停止,需要大量的剎車力。因此,必須減速剎車產(chǎn)生的馬力的發(fā)動機(jī)作用多次。為了發(fā)展須持有對鼓或盤制動器襯片的力量,實(shí)現(xiàn)受控減速,這是要乘原始的力量施加在剎車踏板。
當(dāng)使用液壓系統(tǒng),機(jī)械杠桿是在腳踏板聯(lián)動。然而,不同分泵或卡尺直徑的直徑,關(guān)系到主缸內(nèi)徑,提供了一個(gè)額外增加的比率。液壓系統(tǒng)中,各分泵交付的壓力,直接影響由活塞地區(qū)。例如,如果一個(gè)輪缸活塞面積2平方英寸,另一個(gè)活塞面積1平方英寸,系統(tǒng)壓力為400磅,2平方英寸的活塞將針對制動器推一個(gè)迫使800磅。1平方英寸的活塞施加一個(gè)400磅的力量??偙煤头直玫牡貐^(qū)之間的比例確定在輪缸活塞的力量倍增。為保持在頭腦,直徑較大的輪缸的,更流暢,必須提供由主缸行程較長的碩士轉(zhuǎn)化。請記住,直徑較大的輪缸的,更流暢,必須由主缸提供,以填補(bǔ)它。這意味著進(jìn)入一個(gè)較長的主缸行程。如果主缸孔直徑增加和相同的申請仍然有效,更少的壓力將在系統(tǒng)的開發(fā),但一個(gè)更大的輪缸活塞可以用來實(shí)現(xiàn)在輪缸所需的壓力。顯然,必須更換主缸,輪缸或卡尺相同的設(shè)計(jì),并作為原單位承擔(dān)。
液壓系統(tǒng)中,各分泵交付的壓力,直接影響由活塞地區(qū)。例如,如果一個(gè)輪缸活塞面積2平方英寸,另一個(gè)活塞面積1平方英寸,系統(tǒng)壓力為400磅,2平方英寸的活塞將針對制動鞋推一個(gè)迫使800磅。 1平方英寸的活塞施加一個(gè)400磅的力量??偙煤头直玫牡貐^(qū)之間的比例確定在輪缸活塞的力量倍增。液壓制動系統(tǒng)分割的系統(tǒng),包括兩個(gè)謹(jǐn)慎的制動電路。一主缸活塞和水庫是一個(gè)單獨(dú)的活塞及伺服制動器上的其他橋(S)的水庫,用來驅(qū)動一軸剎車。雖然罕見,一些輕型制動系統(tǒng)分裂對角線而非橋橋。分割系統(tǒng)的原因是,如果一個(gè)液壓回路泄漏的發(fā)展,將停止車輛。當(dāng)然,不應(yīng)該被驅(qū)動的車輛遠(yuǎn)超過必要的制動系統(tǒng)修復(fù)。當(dāng)液壓回路發(fā)生故障,壓力差開關(guān)感官兩個(gè)電路之間的不平等的壓力。交換機(jī)包含由彈簧片,并在每年年底電觸頭位于活塞。從一個(gè)液壓回路中流體的壓力提供壓力差開關(guān)的一端,并從其他電路的壓力提供給另一端。隨著壓力的一個(gè)電路,其他電路的正常壓力,迫使活塞的失效一邊,關(guān)閉的接觸,并照亮儀表板警示燈。
動力輔助
協(xié)助電力單位,或助推器,減少運(yùn)營商的努力,在剎車踏板。真空助力器,輕型汽車的流行,使發(fā)動機(jī)真空隔膜一側(cè),對對方的大氣壓力。一個(gè)閥門,使真空作用于剎車踏板的行程中的比例隔膜。這有助于踏板的努力,并增加對制動液的壓力,無需過分增加在踏板努力。其他類型的助推器使用液壓壓力 - 無論是從車輛的動力轉(zhuǎn)向泵,或從一個(gè)單獨(dú)的電動泵,或兩者兼而有之 - 協(xié)助剎車踏板被踩下踏板作用,閥門液壓升壓室申請?jiān)黾拥膲毫υ谠黾又鞲谆钊?。有些系統(tǒng)使用真空和液壓助力。在其他系統(tǒng)中,從船上壓縮機(jī)的空氣壓力產(chǎn)生液壓系統(tǒng)的壓力。
閥桿液壓制動系統(tǒng)中常見的閥門包括:
配比,或壓力平衡閥門。這些限制液壓比例后輪剎車系統(tǒng)壓力達(dá)到預(yù)設(shè)的高阻值。提高前輪/后輪在高速制動的制動平衡時(shí),一些車輛的前后重量轉(zhuǎn)移,并有助于防止后輪配料閥高度傳感器。也就是說,他們調(diào)整后輪制動壓力,在車輛荷載的響應(yīng)。隨著車輛的負(fù)載增加(降低高度)液壓后輪剎車是不允許的; ?測光閥門。這些保持了前盤式制動器的壓力,讓后輪鼓式制動蹄克服返回彈簧的壓力,使接觸后鼓。這可以防止鎖定在濕滑路面上的前剎車燈制動應(yīng)用。這些閥門不來硬制動過程中發(fā)揮作用。
泊車
停車功能的液壓制動系統(tǒng)之間的差別很大。許多輕型車輛使用與后輪鼓式制動器桿和電纜相配合,逐步加大桿或腳踏拉電纜,這反過來,拉杠桿總成,每個(gè)后輪結(jié)束的客運(yùn)車類型。杠桿迫使制動蹄外,他們對鼓機(jī)械棘輪被釋放,直到舉起。
其他泊車系統(tǒng)包括彈簧腔,像那些用于空氣制動系統(tǒng)。這是彈簧控制,但由液壓脫開而不是空氣。
防抱死
許多輕型卡車液壓制動,防抱死制動系統(tǒng)上使用的后輪保持輕載時(shí),這些車輛制動穩(wěn)定性。前面和后輪防抱死通常是一個(gè)選項(xiàng),GVWR超過10,000磅的車輛,這是需要引導(dǎo)和驅(qū)動橋防抱死關(guān)閉。在當(dāng)前的液壓防抱死系統(tǒng),轉(zhuǎn)儲閥釋放壓力到一個(gè)累加器在即將車輪鎖死的情況下液壓油。
電子控制箱接收來自傳感器的傳輸和/或在車輪速度信號(S)。當(dāng)施加制動,控制箱檢測在后輪的速度,減少和激活轉(zhuǎn)儲閥(S),如果減速率超過預(yù)定的限制。
控制箱通電一系列流血輪液壓快速脈沖的單向閥。繼續(xù)轉(zhuǎn)儲閥是脈沖在防抱死模式,以保持車輪轉(zhuǎn)動,同時(shí)保持控制的減速。在最后的停止,閥門的激勵(lì)和累加器中的任何液體返回到主缸,恢復(fù)正常的剎車操作。
基礎(chǔ)剎車
在液壓系統(tǒng)的基礎(chǔ)制動器可以是鼓或光盤。在許多應(yīng)用中,光盤上使用前軸后方的鼓。鼓式制動器說是自激。這是因?yàn)橹苿犹銛U(kuò)大和聯(lián)系一個(gè)旋轉(zhuǎn)的滾筒,引導(dǎo)或向前制動蹄被推向?qū)x車制動箍由移動鼓的力量。這個(gè)結(jié)果在更高的襯里鼓比將僅由輪缸產(chǎn)生的壓力。
隨著制動器襯片的磨損,必須定期移近鼓,以確保在制動過程中適當(dāng)?shù)慕佑|。雖然一些舊的鼓式制動器總成,手動調(diào)整,大部分都是自動。這些使用一個(gè)星輪或棘輪大會,這感官分泵時(shí)已超出其正常行程前往,并擴(kuò)大在另一端的制動蹄的支點(diǎn)。
除了摩擦的元素之一,制動鼓或轉(zhuǎn)子也充當(dāng)散熱器。它必須迅速制動過程中吸收的熱量,并保持它,直到它可以將空氣中消散。鼓或轉(zhuǎn)子較重的是,它可以容納更多的熱量。這是很重要的,因?yàn)橹苿悠饕r片熱,他們更容易受到熱衰退。熱衰退是誘發(fā)重復(fù)的硬盤停止和結(jié)果的減少鼓形輪子連接的摩擦和增加車輛的制動距離。作為一項(xiàng)規(guī)則,高品質(zhì)的襯里,將顯示低于劣質(zhì)的熱褪色。此外碟式剎車比鼓式制動器耐熱褪色性能更好。
另一個(gè)褪色的類型,剎車容易褪色水。鼓式制動器,其表面積大,在安全范圍內(nèi)比盤式制動器每平方英寸之間需要更少的襯力和鼓力。加上鼓的保水的形狀,鞋和鼓之間的潮濕條件下促進(jìn)水面滑行。結(jié)果是制動距離大大增加。
盤式制動器,具有較小的摩擦表面和高夾緊力,做一個(gè)良好的工作從轉(zhuǎn)子擦水,并顯示在潮濕時(shí)停止能力幾乎沒有減少。
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河南理工大學(xué)
本科畢業(yè)設(shè)計(jì)(論文)開題報(bào)告
設(shè) 計(jì) 題 目: 汽車制動器設(shè)計(jì)
學(xué) 生:
指 導(dǎo) 教 師:
專 業(yè):
學(xué) 號:
河南理工大學(xué)
本科畢業(yè)設(shè)計(jì)(論文)開題報(bào)告
題目名稱
汽車制動器設(shè)計(jì)
學(xué)生姓名
專業(yè)班級
學(xué)號
一、 選題的目的和意義:
隨著高速公路的迅速發(fā)展和車速的提高以及車流密度的日益增大,為了保證行駛安全、停車可靠,汽車制動系的工作可靠性顯得日益重要。也只有制動性能良好。制動器工作可靠的汽車才能充分發(fā)揮動力性能。汽車的制動系是汽車行車安全的保證,許多制動法規(guī)對制動系提出了許多詳細(xì)而具體的要求,這是我們設(shè)計(jì)的出發(fā)點(diǎn)。而一個(gè)制動系的主要部件就是制動器,這就是預(yù)示著制動器的性能能不能滿足制動系的需要尤為重要,因此制動器的研發(fā)和設(shè)計(jì)對于汽車行業(yè)的發(fā)展非常重要,尤其是對于車流量較大的地區(qū)或城市更顯得必要。
選題的目的在于,結(jié)合實(shí)際問題,對汽車制動系的工作工作方法進(jìn)行研究分析,
探尋各種環(huán)境狀況下的汽車制動器的工作性能,從而選擇出比較好的制動器設(shè)計(jì)方法
將制動系的,工作性能發(fā)揮出來,并結(jié)合其社會和經(jīng)濟(jì)效益,確定出比較好的設(shè)計(jì)方案
二、 國內(nèi)外研究綜述:
現(xiàn)代汽車制動器的發(fā)展起源于原始的機(jī)械控制裝置,最原始的制動控制只是駕駛員操縱一組簡單的機(jī)械裝置向制動器施加作用力,那時(shí)的汽車重量比較小,速度比較低,機(jī)械制動已經(jīng)能夠滿足汽車制動的需要,但隨著汽車自身重量的增加,助力裝置對機(jī)械制動器來說越來越顯得非常重要。從而開始出現(xiàn)了真空助力裝置。1932年生產(chǎn)重量為2860kg的凱迪拉克V16車四輪采用直徑419.1mm的鼓式制動器,并有制動踏板控制的真空助力裝置。林肯公司也于1932年推出V12轎車,該車采用通過四根軟索控制真空助力器的鼓式制動器。隨著科學(xué)技術(shù)的發(fā)展及汽車工業(yè)的發(fā)展,尤其是軍用車輛及軍用技術(shù)的發(fā)展,車輛制動有了新的突破,液壓制動是繼機(jī)械制動后的又一重大革新。DuesenbergEight車率先使用了轎車液壓制動器,克萊斯勒的四輪液壓制動器于1924年問世,美國通用汽車公司和福特汽車公司分別于1934年和1939年采用了液壓制動技術(shù)。到20世紀(jì)50年代,液壓助力制動器才成為現(xiàn)實(shí)。經(jīng)過80多年的發(fā)展,液壓制動技術(shù)是如今最成熟、最經(jīng)濟(jì)的制動技術(shù),并應(yīng)用在當(dāng)前絕大多數(shù)乘用車上。汽車液壓制動系統(tǒng)可以分為行車制動、輔助制動、伺服制動等,主要制動部件包括制動踏板機(jī)構(gòu)、真空助力器、制動主缸、制動軟管、比例閥、制動器和制動警示燈等。在制動系統(tǒng),真空助力器、制動主缸和剎車制動器是最為重要的部分,另外,汽車防抱死制動系統(tǒng)(ABS)也已經(jīng)成為電子制動的標(biāo)準(zhǔn)配置。
真空助力器總成
現(xiàn)在汽車配套出于安全可靠方面的考慮,真空助力器往往和制動主缸一起形成真空助力器總成給車型配套。從中國汽車工業(yè)協(xié)會每年統(tǒng)計(jì)的20多家國內(nèi)主要真空助力器總成生產(chǎn)企業(yè)來看,伴隨著2000年以來我國汽車產(chǎn)量的發(fā)展,我國汽車真空助力器總成也獲得了較快的發(fā)展,產(chǎn)量從2000年的193.89萬套發(fā)展到2007年的650萬套。根據(jù)汽車工業(yè)協(xié)會統(tǒng)計(jì)的數(shù)據(jù)來看,2004年我國平均每套真空助力器總成的價(jià)格是270元,2004年我國乘用車產(chǎn)量315萬輛,粗略計(jì)算我國真空助力器總成2004年的市場需求規(guī)模在8.6億元。2007年我國乘用車產(chǎn)量638萬輛,但真空助力器總成的配套價(jià)格有所降低,約在250元左右,因此,2007年真空助力器的市場需求規(guī)模在16億元左右。
鼓式制動器總成
目前,國內(nèi)主要從事鼓式制動器總成的企業(yè)有萬向錢潮、亞太機(jī)電、重慶紅宇等一些企業(yè)。2004年前八家企業(yè)產(chǎn)量集中度達(dá)到85.4%。隨著近幾年汽車盤式制動器的發(fā)展,液壓鼓式制動器目前只在一些比較低檔的經(jīng)濟(jì)型轎車上在使用。根據(jù)慧聰汽車市場研究所最新的統(tǒng)計(jì)表明,2008年1~7月,我國乘用車中剎車制動器用鼓式制動器只占20%,并且鼓式制動器目前已經(jīng)徹底退出前輪制動。目前鼓式制動器只有在商用車上還占有絕大的比例,采用的是氣壓鼓式制動系統(tǒng)。
盤式制動器總成
2000年以來,我國盤式制動器市場需求增長速度發(fā)展非??臁闹袊嚬I(yè)協(xié)會統(tǒng)計(jì)的情況來看,2000年我國盤式制動器的產(chǎn)量只有57.58萬套,到2004年迅速增長到468.72萬套,增長7倍多,年平均增長率高達(dá)68.9%,2007年增長至1000萬套。過去5年里,我國盤式制動器應(yīng)用的增長非常迅速。國內(nèi)從事盤式制動器的企業(yè)近年來也逐漸在增多,目前主要生產(chǎn)企業(yè)有亞太機(jī)電、重慶紅宇、萬向錢潮、浙江萬安等企業(yè)。亞太機(jī)電一直是我國盤式制動器產(chǎn)量最大的企業(yè)。
三、 畢業(yè)設(shè)計(jì)(論文)所用的主要技術(shù)與方法:
理論研究法:對于制動系統(tǒng)和制動器工作原理進(jìn)行學(xué)習(xí)研究,鞏固對制動系統(tǒng)知識的理解和掌握,增強(qiáng)自己分析問題和解決問題的能力
對比分析法:通過對制動器的幾種設(shè)計(jì)原理的分析,結(jié)合實(shí)習(xí)需要和相應(yīng)的技術(shù)規(guī)范,以及社會和經(jīng)濟(jì)效益,選擇較優(yōu)的設(shè)計(jì)實(shí)施方案。
參與實(shí)踐驗(yàn)證法:在焦作汽車大修廠進(jìn)行實(shí)際的制動器拆卸安裝和實(shí)際考察,對選定設(shè)計(jì)方案進(jìn)行對比,進(jìn)行實(shí)踐驗(yàn)證,增加說服力
四、 主要參考文獻(xiàn)與資料獲得情況:
《汽車構(gòu)造》陳家瑞 ,人名交通出版社,2008年
《汽車設(shè)計(jì)》劉惟信 ,清華大學(xué)出版社,2001年
《機(jī)械設(shè)計(jì)》程光蘊(yùn) ,高等教育出版社,2004年
《機(jī)械原理》張春林 ,高等教育出版社,2005年
《汽車設(shè)計(jì)》王望予 ,機(jī)械設(shè)計(jì)出版社.2000
《汽車構(gòu)造》陳家瑞 ,機(jī)械工業(yè)出版社.2000
文獻(xiàn):《國外汽車制動器襯片摩擦系數(shù)標(biāo)志與識別》
五、 畢業(yè)設(shè)計(jì)(論文)進(jìn)度安排(按周說明)
第10周(3月29日——4月3日)撰寫開題報(bào)告,整理已有文獻(xiàn)資料。
第11周(4月7日——4月13日)撰寫論文提綱,確定文章框架結(jié)構(gòu)。
第12周(4月14日——4月23日)完成正文部分,形成初稿。
第13周(4月24日——4月27日)根據(jù)指導(dǎo)教師意見,對初稿進(jìn)行修改。
第14周(4月27日——5月1日)根據(jù)指導(dǎo)教師意見,對論文進(jìn)行再次完善。
第15周(5月2日——5月5日)論文定稿,裝訂成冊。
六、 指導(dǎo)教師審批意見:
指導(dǎo)教師: (簽名)
年 月 日
6
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