汽车底盘构造—变速器2ppt课件

1、 汽车底盘构造 变速器与分动器主讲孟庆雨 第一节第一节 变速器的功用和类型变速器的功用和类型n 功用：功用： n （1改变传动比，扩大驱动轮转矩和转速改变传动比，扩大驱动轮转矩和转速的变化范围，以适应经常变化的行驶条件，使的变化范围，以适应经常变化的行驶条件，使发动机在有利的工况下工作。发动机在有利的工况下工作。 n （2在发动机旋转方向不变的前提下，使在发动机旋转方向不变的前提下，使汽车倒退行驶。汽车倒退行驶。 n （3利用空档中断动力传递，以使发动机利用空档中断动力传递，以使发动机能够起动、怠速，并便于变速器换档或进行动能够起动、怠速，并便于变速器换档或进行动力输出。力输出。1.变速器的功

2、用和组成2.变速器的类型变速器的类型1按传动比变化方式不同：按传动比变化方式不同：有级式变速器；用齿轮传动，有若干个定值传有级式变速器；用齿轮传动，有若干个定值传动比动比无级式变速器：采用电力或液力变矩器传动，无级式变速器：采用电力或液力变矩器传动，传动比可在一定的数值范围内连续变化。传动比可在一定的数值范围内连续变化。 综合式变速器：综合式变速器： 由液力变矩器和行星齿轮式变速器组成，传由液力变矩器和行星齿轮式变速器组成，传动比可在几个范围内连续变化。动比可在几个范围内连续变化。2按操纵方式不同：按操纵方式不同：强制操纵式：靠驾驶员直接操纵变速杆换档强制操纵式：靠驾驶员直接操纵变速杆换档 。

3、自动操纵式：换档自动进行。自动操纵式：换档自动进行。 半自动操纵式：常用的几个档位自动操纵；预半自动操纵式：常用的几个档位自动操纵；预选式选式变速器组成变速器组成变速传动机构：改变转速比、改变转矩、改变方向操纵机构：实现换档3.变速器的组成变速器的组成变速传动机构（按传动齿轮轴数）三轴式齿轮变速传动两轴式齿轮变速传动第二节 变速器的变速传动机构一、有级式变速器变速传动机构的组成、工作原理和常见的换档方式1.变速传动机构的组成变速传动机构主要由齿轮、轴及变速器壳体等零部件组成。第二节 变速器的变速传动机构输入轴中间轴输出轴倒档轴变速齿轮结合套壳体2.变速传动机构的工作变速传动机构的工作原理原理

4、1） 利用不同齿数利用不同齿数的齿轮对相互啮合，的齿轮对相互啮合，以改变变速器的传动以改变变速器的传动比；比；i12=n1/n2= z2/z1= M2/M1z1 ，n1 ， M1为主动为主动齿轮的参数。齿轮的参数。 z2 ，n2 ， M2为从动为从动齿轮的参数。齿轮的参数。从动轮2主动轮1i=主动齿轮齿数主动齿轮齿数从动齿轮齿数从动齿轮齿数GearsGears are used to multiply either torque or speed as power is transferred from one shaft to another. In this case the gear r

5、atio is 40 20 or 2:1. The blue gear will have twice the torque but one-half the speed as the green gear.Input: 20 TeethOutput: 40 TeethGear TypesThe most common gear types are Spur (left) and Helical (right) gears. Spur gears have the teeth cut parallel to the shaft. The teeth of a helical gear are

6、cut at an angle. A helical gear runs quieter, costs more, and generates a side thrust under load.Spur GearsHelical Gearsn 2通过增加齿轮传动的对数，以实现倒档。 Idler GearsAn Idler gear (orange) can be put in a gear train to reverse direction of rotation. A simple idler, as shown, will not change the gear ratio. In th

7、is case, the gear ratio is 40 (blue output gear) divided by 20 (green input gear) = 2:1, and both the input and output rotate clockwise.Clockwise RotationIdler Gear, Counterclockwise Rotation3常见的换档方式（1利用滑动齿轮换档 冲击、噪声、损坏齿端面、舒适性降低。倒挡常用。（2利用接合套换档 同时承受换档冲击的齿数多，轮齿不参与换档，不会发生早期损坏。不能消除换档冲击。（3利用同步器换档 迅速、无冲击、无

8、噪声换档 ；与熟练程度无关。加速性、经济性和行驶安全性提高。二、两轴式变速器Manual Transaxle OperationPurposeA manual transaxle is used in many FWD vehicles. It provides various gear ratios that are necessary to transfer power from the engine and clutch to the drive shafts and wheels.To ClutchTo Drive shaftConstructionMost transaxles ha

9、ve three major shafts:an input shaft that connects to the clutch disc with the driving gears, a main/intermediate shaft with the driven gears, andthe output shaft with the differentialInput ShaftIntermediate ShaftOutput: Final Drive & DifferentialBearingsA pair of tapered roller bearings (orange

10、) are used to support each of the two major shafts and differential. This type of bearing allows the shaft to rotate freely, but eliminates any end play. Some transmissions use ball bearings for this same purpose.优点：直径较小；宽度较大；容量大；可承受高负荷；三元件基本位置关系能使滚子正确对中，轴承可靠性和寿命提高；轴和齿轮的刚度提高，齿轮噪声降低，减少脱档可能。Speed Gear

11、s & SynchronizersA synchronizer assembly normally has a speed gear positioned on each side of it. The speed gears float on the shaft. The synchronizer sleeve engages the clutching teeth of the speed gear to transfer its motion to the shaft.1st 4th 3rd Rev. 5th 2nd Fixed GearsOne of the gears, ei

12、ther the driving or driven gear, for each gear ratio is fixed solidly to one of the shafts. It meshes with a speed gear to provide the proper gear ratio.Rev. 5th 2nd 1st 4th 3rd Shifting GearsA rather complex mechanism connects the gear shift lever to the shift forks inside the transaxle. The shift

13、forks move the synchronizer sleeves to make the shifts from one gear range to another.To Shift LeverShift ForkNeutralIf each of the synchronizers assemblies is in neutral and the reverse idler gear is not in mesh, power is not able to get from the input shaft to the intermediate shaft. The input sha

14、ft and the speed gears can rotate, but the intermediate shaft will not be driven.All synchros. are in neutral, center position1st GearThis is the lowest gear ratio with the smallest gear on the input shaft driving the largest gear on the intermediate shaft. In this example a 12 tooth gear drives a 4

15、2 tooth gear. 42 12 = 3.501st Gear, Driving1st Gear, Driven1-2 Synchro., Shifted to 1st2nd GearThe 1-2 synchronizer is moved to engage the 2nd speed gear. Now a 14 tooth gear drives a 35 tooth gear. The ratio is: 35 14 = 2.502nd Gear, Driving2nd Gear, Driven1-2 Synchro., Shifted to 2nd 3rd GearWith

16、the 1-2 synchronizer in neutral, the 3-4 synchronizer is moved to engage the 17 tooth speed gear. It drives a 21 tooth gear. The ratio is 21 17 = 1.24:1.3rd Gear, Driving3rd Gear, Driven3-4 Synchro., Shifted to 3rd 4th GearThe 3-4 synchronizer is moved to engage the 19 tooth speed gear that is drive

17、s an 18 tooth gear. The ratio is 18 19 = 0.95:1. Note that this is an overdrive ratio so the intermediate shaft will rotate faster than the input shaft.4th Gear, Driving4th Gear, Driven3-4 Synchro. Shifted to 4th 5th GearThe 5th gear synchronizer is moved to engage the 15 tooth 5th speed gear. It is

18、 driven by a 20 tooth gear so the ratio is 15 20 = 0.75:1, another overdrive ratio.5th Gear, Driving5th Gear, Driven5-Rev Synchro. Shifted to 5thReverseThe 5-Reverse synchro. is shifted into mesh with the 42 tooth Rev. speed gear. A 12 tooth Rev. Gear drives it. The idler gear is used to change the

19、direction of rotation. The ratio is 42 12 = 3.50:1Rev. Gear, DrivingRev. Gear, Driven5-Rev. Synchro. Shifted to Rev.Rev. Idler GearOther Reverse TypesSome transaxles construct the 1-2 synchronizer sleeve with the reverse gear teeth surrounding it. The reverse idler gear is shifted into mesh with the

20、 reverse drive gear and the driven gear on the synchro. Sleeve. This is difficult to illustrate because the idler gear and shaft are positioned behind the other gears.Rev. Idler GearRev. Drive Gear1-2 Synchro. + 1st & 2nd Speed GearsRev. Driven GearInput ShaftFinal DriveA 20 tooth gear on the in

21、termediate shaft drives the 80 tooth ring gear on the differential. Power is transferred from the ring gear to the differential case and through the differential gears to the CV joints and front driveshafts. The ratio is 80 20 = 4:1Pinion GearRing GearDiff. Side GearDiff. Pinion GearCV JointOverall

22、RatiosThe overall ratio between the engine and the drive wheels is effected by both gear ratios. These ratios become: 1st gear: 3.50 X 4 = 14:1 2nd gear: 2.50 X 4 = 10:1 3rd Gear: 1.24 X 4 = 4.96:1 4th Gear: 0.95 X 4 = 3.80:15th Gear: 0.75 X 4 = 3:1 Reverse: 3.50 X 4 = 14:1二、两轴式变速器二、两轴式变速器n运用：运用： FF

23、 RR n特点：特点： n 输入轴与输出轴平行，无中间轴。输入轴与输出轴平行，无中间轴。 n组成：组成： n 输入轴、输出轴、倒档轴、轴承、变输入轴、输出轴、倒档轴、轴承、变速齿轮速齿轮桑塔纳轿车变速器结构简图桑塔纳轿车变速器结构简图桑塔纳轿车两轴式变速器桑塔纳轿车两轴式变速器n结构分析：结构分析：n一轴：一、二档齿轮与轴一体；三、四档齿轮与轴通过轴承空套一轴：一、二档齿轮与轴一体；三、四档齿轮与轴通过轴承空套轴上。轴上。 n二轴：一、二档齿轮与通过轴承连接；三、四档齿轮与轴一体。二轴：一、二档齿轮与通过轴承连接；三、四档齿轮与轴一体。一、二档传动路线三、四档传动路线倒档传动路线三、三轴式变速

24、器 三轴是指汽车前进时，传递动力的轴有第一轴、中间轴和第二轴，直接档除外。 换档原理一轴中间轴二轴三轴式变速器结构图传动方向结合齿圈结合套齿花键毂 跳档方向四、防止自动跳档的措施四、防止自动跳档的措施 （1切薄齿式切薄齿式利用接合套换档的变速器，由于接合套与齿圈利用接合套换档的变速器，由于接合套与齿圈的接合长度较短，同时汽车行驶时需要经常换的接合长度较短，同时汽车行驶时需要经常换档，频繁拨动接合套将使齿端发生磨损。汽车档，频繁拨动接合套将使齿端发生磨损。汽车行驶中可能会因振动等原因造成接合套与齿圈行驶中可能会因振动等原因造成接合套与齿圈脱离啮合，即发生自动跳档。脱离啮合，即发生自动跳档。（2斜

25、面齿式斜面齿式结合齿圈结合套齿花键毂结合齿圈传动方向接合套和接合齿圈的齿端制成倒斜面（3接合套的齿端制成凸肩接合套的齿端制成凸肩 五、组合式变速器5-Speed Manual TransmissionPurposeA manual transmission is used in many RWD and 4WD vehicles. It provides the various gear ratios that are necessary to transfer power from the engine and clutch to the drive shafts and wheels.En

26、gine Clutch Transmission Driveshaft Drive AxleConstructionManual transmissions have three major shafts: an input shaft/ main drive gear that connects to the clutch disc, a counter shaft that is commonly called a cluster gear, and the main shaft/output shaft with the driven gears and synchronizers.Ma

27、in ShaftInput ShaftCluster GearBearingsThe main drive gear and main shaft are each supported by a ball or roller bearing with a pilot bearing where the main shaft fits into the main drive gear. The cluster gear is supported by a pair of bearings. These bearings are colored orange.Cluster Gear Bearin

28、gsMain shaft bearingPilot BearingMain Drive Gear BearingSpeed Gears & SynchronizersA synchronizer assembly normally has two speed gears, one on each side of it. The speed gears float on the main shaft. The synchronizer sleeve engages the clutching teeth of a speed gear to transfer its motion to

29、the shaft.1-2 Synchro.3-4 Synchro.5-Rev. Synchro.3rd Speed Gear2nd Speed Gear5th Speed Gear1st Speed GearReverse Speed Gear6-Speed Main Shaft3-4 Synchro. 1-2 Synchro. 5-6 Driven Gear Rev. Synchro. OutputSpeed Gear Journals:3rd 2nd 1st ReverseThis mainshaft has 3 splined areas that connect to the syn

30、chronizer hubs, a set of splines for the 5-6 fixed/driven gear, 1 set of output splines for the drive shaft slip joint. And 4 smooth journals for the speed gears.Fixed GearsThe main drive gear and cluster gears are normally made as part of their shaft. These are the driving gears for each of the gea

31、r ranges.Shifting GearsMost SUV and pickup transmissions incorporate the shift mechanism into the the top of the unit. Movement of the gear shit lever will move one of the shift forks connected to the synchronizer sleeve.Shift LeverShift RailShift ForkShift DetentsMost detents are spring-loaded ball

32、s (red) that are pushed into one of two or three notches in a shift rail or cam. They are used to hold the shift rail in an exact position which places the synchro. sleeve or gear in an exact position. The center shift rail detents are in back of the rail.Detent Ball Detent SpringShift Rail Shift Fo

33、rkShift InterlocksThis 5-speed transmission has three shift rails that transmit motion from the shift lever to the shift forks. When one of the rails is moved from neutral, the plugs are moved sideways to lock the other rails in placeShift RailsPlug Pin PlugNeutralIf each of the synchronizers assemb

34、lies is in neutral and the reverse idler gear is not in mesh, power is not able to get from the speed gears to the main shaft. The input shaft, cluster gear, and speed gears rotate but not the main shaft.All Synchros. In neutral, center positionNeutralIn neutral with the clutch engaged, the input sh

35、aft will spin, but there will be no power transferred. Input from clutchOutput to drive shaftNeutral power flow5-Speed gearboxDouble ReductionManual transmission gear ratios are effected by two gear sets. The first (input) is the ratio between the main drive gear and cluster gear. The second is the

36、ratio between the drive and driven gears for each gear range.15 Tooth Main Drive Gear20 Tooth Cluster Gear1st GearsInput reduction: 20 15 = 1.33:1 Reduction, 1st Gears: 3:1 1st Gear Ratio: 1.3 X 3 = 3.9:11st GearThe 1-2 synchronizer is moved to engage the clutching teeth on the 45 tooth 1st speed ge

37、ar. It is driven by a 15 tooth gear on the cluster gear. The 1st gear ratio is 3.9:1.1-2 Synchro. Shifted to 1st 1st Speed Gear, Driven1st Gear, Driving2nd GearThe 1-2 synchronizer is moved to engage the 40 tooth, 2nd speed gear. It is driven by a 20 tooth gear on the cluster gear. The cluster to ma

38、in shaft ratio is 1.3:1, and the 2nd gear ratio is 2:1 X 1.3:1 = 2.6:1.2nd Speed Gear, Driven2nd Gear, Driving1-2 Synchro. Shifted to 2nd 3rd GearThe 3-4 synchronizer is moved to engage the 20 tooth 3rd speed gear. It is driven be a 15 tooth gear on the cluster gear. The gear ratio is: 1.3:1 X 1.3:1

39、 = 1.69:1.3-4 Synchro. Shifted to 3rd 3rd Gear, Driving3rd Gear, Driven4th GearThe 3-4 synchronizer is moved to engage the clutching teeth on the main drive gear. Power is transmitted directly to the main shaft so the ratio is 1:1, direct drive.3-4 Synchro. Shifted to 4th Main Drive GearMain Shaft5t

40、h GearThe 5-Rev. synchronizer is moved to engage the 20 tooth 5th speed gear. It is driven by a 30 tooth gear that is part of the cluster gear. The ratio is 0.66:1 X 1.3:1 = 0.86:15th Gear, Driving5-Rev. Synchro Shifted to 5th5th Gear, DrivenOther 5th Gear TypesThe 5th driving gear in this transmiss

41、ion is a speed gear mounted on the cluster gear along with the 5th gear synchronizer. The 5th driven gear is attached to the mainshaft.5th Driven Gear5th Gear Synchronizer5th Speed GearReverseThe 5-Reverse synchro. is shifted into mesh with the 45 tooth Rev. speed gear. A 15 tooth Rev. gear on the c

42、luster drives it through the Rev. idler gear. The idler gear is used to change the direction of rotation. The reverse gear ratio is 3:1 X 1.3:1 = 3.9:1.5-Rev. Synchro. Shifted to Rev.Rev. Gear, DrivingRev. Idler GearRev. Gear, DrivenRev. Gear, DrivenOther Reverse TypesSome 4 & 5 speed transmissi

43、ons use a reverse driven gear that surrounds the 1-2 synchronizer sleeve. The reverse idler gear (mounted behind the other gears) is shifted into mesh with the reverse driving gear on the cluster gear and the reverse driven gear. All three of these gears are spur gears.Reverse Driven GearReverse Dri

44、ve GearReverse Idler Gear第三节第三节 同步器同步器n无同步器时变速器的换档过程无同步器时变速器的换档过程 1、从低档换入高档、从低档换入高档脱离瞬间：脱离瞬间： V4=VJ V5VJ、 V4 保持空档片刻保持空档片刻 V5降低，降低，VJ、 V4变变化不大化不大 在在VJ与与V5相等时挂入相等时挂入五档五档 五档齿轮四档齿轮中间轴结合套花键毂结合齿圈结合齿圈2、从高档换入低档、从高档换入低档n脱离瞬间：脱离瞬间： nV5=VJn V4VJ、 V5 n抬起离合器踏板，踩抬起离合器踏板，踩一下油门踏板一下油门踏板 ，V4升升高，高，VJ变化不大变化不大 n在在VJ与与V4

45、相等时挂入相等时挂入四档四档五档齿轮四档齿轮中间轴结合套花键毂结合齿圈结合齿圈四档工作：V3=V4，欲换档踩离合器接合套左移处空挡因V4V2 V3V4V3V4空档时：V4比V3下降得快，直线V3、V4不会有交点，不可能达到自然同步状态，驾驶员应在变速器退到空档后，立即抬起离合器，同时踩加速踏板，使发动机连同离合器和第一轴都从B点升速，让V4V3，再踩离合器等到V3=V4，可以换档。V3V4t2t3tVBAAV3V4二、同步器构造及工作原理二、同步器构造及工作原理1、功用：使结合套与待啮合齿圈迅速同步，、功用：使结合套与待啮合齿圈迅速同步，缩短换档时间，同时防止啮合时齿间冲击。缩短换档时间，同时

46、防止啮合时齿间冲击。 2、构造：、构造： 结合套、花键榖、对应齿轮上的结合齿圈、结合套、花键榖、对应齿轮上的结合齿圈、同步装置、锁止装置。同步装置、锁止装置。 3、同步器分类：、同步器分类： 常压式、惯性式、自增力式常压式、惯性式、自增力式 惯性式同步器分类：惯性式同步器分类：锁环式惯性同步器锁环式惯性同步器 锁销式惯性同步器锁销式惯性同步器1.锁环式惯性同步器sintanrfRr为锁止面平均半径；为锁止面锁止角;R摩擦锥面平均半径; 锥面半锥角锁环式惯性同步器锁环式惯性同步器细牙螺旋槽滑块构造滑块锁环结合齿圈原理原理定位销、滑块锁环结合齿圈1齿厚2. 锁销式惯性同步器锁销式惯性同步器摩擦锥盘

47、摩擦锥环定位销结合套钢球定位销锁销直径较大的摩擦锥面，可产生较大摩擦力矩缩短同步时间。锁销受力锁销受力锁止角Synchronizer OperationSynchronizersThis 5-speed transaxle has 3 synchronizer assemblies. Each one has a neutral and two other gear positions.3-4 Synchro. Assembly1-2 Synchro. Assembly5-Rev Synchro. AssemblySynchronizer ComponentsInput Shaft3-4 Sy

48、nchro.Blocker RingsSpeed Gears with Needle BearingsThe hub of this 3-4 synchronizer is splined onto the input shaft The 3rd and 4th speed gears fit over the needle bearings and the input shaft. This input shaft also has driving gears for 1st, 2nd, and reverse.Synchronizer Assembly, Exploded ViewThis

49、 synchronizer assembly has been taken apart to show the major parts. Most synchronizers have 3 or 4 struts.Energizer SpringsHubSleeveKey/Strut/InsertSynchronizer HubThe keys (green) and energizer springs (red) fit into the hub so the springs will exert an outward pressure on the keys. Note the splin

50、es on the inside of the hub to connect with the shaft.Synchronizer Assembly, Assembled ViewThe sleeve (orange) can slide on the hub (grey). The keys (green) are pushed outward, against the sleeve by the energizer springs (red).Synchronizer SleeveTwo important features of a synchronizer sleeve are th

51、e neutral detent notch around the center of the splines and the spline lock back taper at the ends of each spline. The neutral detent notch engages the hump on the keys. A complete shift places the back taper along side of the clutch teeth back taper.Back TaperNeutral Detent NotchSpeed GearsA speed

52、gear has teeth (blue) that drive or are driven by another gear. It also has clutching teeth (green) that engage the synchronizer sleeve, a smooth cone surface (orange) for the blocker ring, and a smooth inner bore (yellow) for the gear to rotate on.Clutching TeethConeBlocker RingsA blocker ring is a

53、lso called a synchronizer ring or stop ring. A 1-piece, metal blocker ring is used in most older transmissions. Note the grooves (circled) and threads on the inner surface to remove the lubricant from the speed gear cone. The blocker ring floats in the synchronizer assembly and is driven by the keys

54、, positioned in the three notches (red, triple arrow).3-Piece Blocker RingsOuter Blocker RingIntermediate ConeSpeed GearInner Blocker RingSome modern transmissions use paper-lined blocker rings for better shifting. These are 3-piece units. The inner and outer blocker rings are attached to each other

55、 and the synchronizer. The intermediate cone is attached to the speed gear. These transmissions usually require a special lubricant.Blocker Ring OperationWhen the sleeve is shifted to the left, the key will move with it. After a small amount of movement, the key will push the blocker ring against th

56、e speed gear cone, and the blocker ring will try to rotate with the speed gear. Note how much bigger the blocker ring notch is than the key; this allows the key to rotate slightly to block the sleeve.Speed GearSleeve Blocker RingKeyHubEnergizer SpringOperation During ShiftSpeed Gear TravelSleeve Spl

57、ine MovementBlocker Ring MovementSleeve movement at the beginning of a shift, moves the blocker ring to contact the speed gear cone. The blocker ring then rotates slightly so its teeth are blocking the splines in the sleeve. Further shift pressure pushes the blocker ring against the speed gear cone.

58、 This slows the speed gear to the same speed as the synchronizer.Completed ShiftAfter the speed gear slows down, the blocker rings moves aside, and the sleeve can move over the clutch teeth. The shift is complete when the back tapers are side by side as shown in the center.Speed GearSleeveBack Taper

59、sClutching TeethBack TaperThis section of a speed gear shows how the back side of the clutching teeth (light blue) are tapered to become narrower. This taper holds the synchronizer sleeve in place and prevents gear “jump out”.第四节第四节 变速器操纵机构变速器操纵机构n功用：功用： n保证驾驶员能准确可靠地使变速器换入某个档位。保证驾驶员能准确可靠地使变速器换入某个档位。

60、 n要求：要求： n自锁功能：防止自动换档、脱档。自锁功能：防止自动换档、脱档。 n互锁功能：保证变速器不会同时换入两个档位。互锁功能：保证变速器不会同时换入两个档位。 n倒档锁：防止误换倒档。倒档锁：防止误换倒档。 n分类：分类： n直接操纵式直接操纵式 n远距离操纵式远距离操纵式Shifting GearsMost SUV and pickup transmissions incorporate the shift mechanism into the the top of the unit. Movement of the gear shit lever will move one of the shift forks c