汽车英语翻译

1、英文翻译Braking SystemEnergy is required when a vehicle is accelerated from rest to a certain speed. A proportion of that energy is now stored in the vehicle and is called kinetic energy. In order to reduce the speed of the vehicle, the brakes have to convert the kinetic energy to heat energy; the speed

2、 of conversion governs the rate at which the vehicle slows down.The three types of braking systems are in use today: service braking system, parking braking system and additional retarding-braking system. The service braking system and the parking braking system have separate control and transmissio

3、n devices. The service braking system is normally foot-operated, while the parking braking system is hand-operated.Two types of brakes are used in modern cars: drum brakes and disc brakes. Since 1976, all cars have used disc brakes on the front wheels. Most cars use drum brakes on the rear wheels .

4、In both drum and disc brakes, a hydraulic system applies the brakes. The hydraulic system connects the brake pedal to the brake parts at each wheel.These have two shoes, anchored to a stationary back-plate, which are internally expanded to contact the drum by hydraulic cylinders or a mechanical link

5、age.In the case of the simplex brake, C*(brake factor is the sum of the values for the individual shoes, and is 2.0（referred to a specific coefficient of frictionA disadvantage of this design is the great difference in the braking effect between the two brake shoes, and the resulting greatly increas

6、ed wear on the leading shoe. For this reason, the trailing shoe is often equipped with a much thinner lining than the leading shoe.An advantage of this type of brake is the nearly equal brake lining wear on both shoes and the higher internal transmission ratio in comparison to simplex brakes.Many ca

7、rs have 2 L.S. front brakes and L.&T. rear brakes. The more powerful front brakes take advantage of the transference of weight from the rear to the front which occurs when the brakes are applied.Duo-servo drum brakeThis type of drum brake has an application mechanism which is simpler, more reliable

8、and insensitive to temperature. It comprises diaphragm cylinder, automatic slack adjuster, brake shaft and S-cam.The main disadvantage of drum brakes is that the friction area is almost entirely covered by a lining, so most heat must be conducted through the drum to reach the outside air to cool.Exp

9、osed to the air, disc brakes radiate the heat to the air better than drum brakes: This means that the brake can be operated continuously for a longer period, i.e. they have a greater resistance to fade (fall-off in brake efficiency due to heat.Disc brakes as used in most passenger cars are slowly be

10、ginning to be used in commercial vehicles as well. Aside from their use in fast coaches, current use of disc brakes in commercial vehicles is primarily limited to front-axle brakes for commercial vehicles up to a weight of approx. 7.5 t which are driven in a manner similar to passenger cars.The mast

11、er cylinder contains two separate sections, there is a piston in each section and both pistons are connected to a brake pedal in the drivers compartment.When the brake pedal is pushed by the driver, the two pistons move in the two sections of the master cylinder. This forces brake fluid out and thro

12、ugh the brake lines, or tubes, to the brake mechanisms at the wheels. In a typical system, the brake fluid from one section of the master cylinder goes to the two front-wheel brakes. The brake fluid from the other section goes to the two rear-wheel brakes. The purpose of this that, if one section fa

13、ils, the other section will still provide braking.he operating principle of the power-assisted system is the same as for a non-power system. However, braking force is increased through the use of a vacuum booster unit. Atmospheric pressure helps to push the brake pedal. Thus, less muscle effort is r

14、equired.In SI engines, vacuum is generated via a connection to the engine intake manifold, and diesel engines use a vacuum pump.Operation principle (Tandem master cylinder: after passing over snifter hole, the push-rod piston forces the brake fluid into brake circuit . The compression of the spring

15、and the pressure buildup in brake circuit I actuates the intermediate piston, which passes over snifter hole and builds up pressure in brake circuit The port for brake circuit I, which supplies the rear drum brakes, has a pre-pressure valve which assures a residual pressure of approx 150kPa when the

16、 brakes are released. This prevents the entry of air through the wheel-cylinder seals.The more heavily the driver brakes, the greater is the dynamic shifting of weight from the rear axle to the front axle. With the vehicle empty, the braking force at the rear axle may be so great that the rear axle

17、locks before the front axle. This can lead to instability when braking, i.e. to skidding .Braking stability is obtained when, irrespective of vehicle loading, the front axle always locks before the rear axle. The correct braking-force distribution can be achieved by brakepressure-regulating valves w

18、hich are installed in the brake lines to the wheels of the rear axle.A compressor is used as the energy source, and is usually of the plunger type; the intake air is compressed via automatic suction and delivery valves.The combination brake cylinder consists of a single-chamber diaphragm cylinder fo

19、r the service brakes and a spring-brake actuator for the parking brakes. The cylinder and spring brake actuator are in tandem and act on a common pressure rod.Electrohydraulic braking systems are designed to allow electonic control of vehicle braking while retaining a reduced hydraulic system. The E

20、HB control unit receives inputs from sensors connected to the brake pedal. In normal operation, a backup valve is closed and the controller activates the brakes of the wheel through an electric motor driven hydraulic pump. When the controller goes into a fail-safe mode, the backup valve is opened, w

21、hich allows the brakes to be controlled through a conventional hydraulic circuit.In order to brake the vehicle, the field coils are supplied with current (from the battery or alternator and generate a magnetic field. Eddy currents are induced in the rotors as they pass through this field. This gener

22、ates a braking torque whose magnitude is a function of the excitation of the stator coils.he function of an anti-lock, or anti-skid, braking system is to prevent the wheels from locking under hard braking. Maximum braking force is obtained just before the wheels lock and skid. Such anti-skid systems

23、 are useful on slippery surfaces, such as ice and snow, where the wheels may lock easily.The wheel-speed sensor monitors the motion of the wheel. If one wheel shows signs of locking, there is a sharp rise in peripheral wheel deceleration and in wheel slip. If these exceed defined critical values, th

24、e controller sends commands to the solenoid-valve unit to stop or reduce the buildup of wheel-brake pressure until the danger of lock-up has passed. The brake pressure must then be built up again in order to ensure that the wheel is not under-braked.A wheel-speed sensor consists of a toothed pulse r

25、ing and an inductive wheel- speed pickup. The pulse ring is mounted on the hub and , as the rotates, produces in the wheel-speed pickup an A.C. voltage, the frequency of which is proportional to the wheel speed.From the signals from the wheel-speed pickups, these microcomputers calculate the wheel s

26、peeds as well as the wheel decelerations and accelerations. A vehicle reference speed is formed from the wheel speeds of two diagonally opposite wheels. With this reference speed and the individual wheel speeds it is possible to calculate the brake slip for each wheel. If a wheel has a tendency to l

27、ock, this is determined from the wheel-acceleration and slip signals.A separate frame must be light yet strong enough to resist the various loads and road forces. Commercial vehicles normally use a separate steel frame to provide the rigidity needed to support the various loads. The two long side me

28、mbers of channel section are riveted to a number of cross members to give a low weight frame which offers great resistance to bending, twisting.Most cars use a unitized body construction, a combined body and frame. Unitized body construction is lighter than body/frame construction, but noisier. Rubb

29、er mounts are used between the body section and mechanical parts to absorb vibrations. The floor pan is made of sections that support the rear suspension and the transmission.Modern cars have a blend-air system that mixes warm and unwarmed air to heat the car. The heart of the system is the heater c

30、ore . Hot engine coolant flows from the radiator, through the water pump hoses, and to the heater core. Therefore, the heater core is always hot. The temperature of air entering the passenger compartment is controlled by the amount of air moving through the heater core. This heated air is blended wi

31、th fresh, cool air that bypasses the heater. Small doors in the heating system regulate the air-flow. Control levers on the dash panel open and close these doors to direct air to the heat ducts and window defrostersThe purpose of venting systems is to draw in fresh air and remove stale air from the

32、interior of the car. Fresh air venting systems direct air to two different places. First, they can direct outside air into the heater housing. This air either can bypass the coil or it can be heated by the coil. Second, the air can move directly into the passenger compartment through small vent door

33、s in the dash panel or at floor level. Venting also can take place by opening the windows.Levers andswitch to regulate air and heat are located on the dash panel. Some heater controls use small vacuum motors for simpler, more positive action. Others use cables, while some use a combination of the tw

34、o. The vacuum to operate the motors comes from the engine intake manifold.As the compressor raises the pressure of the refrigerant, it also heats it. The hot refrigerant is then pumped into the condenser , where it cools by giving off heat to air passing over the condenser fins. As the refrigerant c

35、ools, it condenses into a liquid. Still under high pressure, the refrigerant passes into the receiver. The receiver acts as a storage tank to furnish refrigerant to the expansion valve at all times. From the receiver, the high-pressure liquid refrigerant passes to the expansion valve.The expansion v

36、alve controls the flow of refrigerant into the evaporator, where a low pressure is maintained by the suction side of the compressor. As it enters the evaporator, the refrigerant begins to boil by absorbing the heat from the air passing over the evaporator core. Having given up its heat to boil the r

37、efrigerant, the air is cooled and passes into the passenger compartment. The refrigerant continues to boil in the evaporator until all the liquid has vaporized. From the evaporator, the refrigerant flows back to the compressor to repeat the cycle.Energy and powerEngines used in automobiles are inter

38、nal combustion heat engines. They convert the chemical energy of the gasoline into heat within a power chamber that is called a combustion chamber. Heat energy released in the combustion chamber raises the temperature of the combustion gases within the chamber. The increase in gas temperature causes

39、 the pressure of the gases to increase. The pressure developed within the combustion chamber is applied to the head of a piston to produce a usable mechanical force, which is then converted into useful mechanical power.Engine terms:Linking the piston by a connecting rod to a crankshaft causes the ga

40、s to rotate the shaft through half a turn. The power stroke uses up the gas, so means must be provided to expel the burnt gas and recharge the cylinder with a fresh petrol-air mixture: this control ofgas movement is the duty of the valves;Engine block:The engine block is the basic frame of the engin

41、e. All other engine parts either fit inside it or fasten to it. It holds the cylinders, water jackets, and oil galleries. The engine block also holds the crankshaft, which fastens to the bottom of the block.Cylinder sleeve:The dry sleeve can be cast in or pressed into a new block or used to recondit

42、ion badly worn or damaged cylinders that cannot easily be rebored.Cylinder head:The cylinder head fastens to the top of the block, just as a roof fits over a house. The underside forms the combustion chamber with the top of the piston. In-line engines of light vehicles have just one cylinder head fo

43、r all cylinders; larger in-line engines can have two or more.The cylinder head carries the valves, valve springs and the rockers on the rocker shaft, this part of the valve gear being worked by push-rods.Oil pan:The oil pump in the lubricating system draws oil from the oil pan and sends it to all wo

44、rking parts in the engine. The oil drains off and runs down into the pan. Thus,there is constant circulation of oil between the pan and the working parts of the engine.Piston assembly:Most pistons are made from cast aluminum. The piston, through the connecting rod, transfers to the crankshaft the fo

45、rce created by the burning fuel mixture. This force turns the crankshaft.Piston :In disel engines, the combustion chamber may be formed totally or in part in the piston crown, depending on method of injection.Piston rings:In modern engines, each piston has three rings. (Piston in older engines somet

46、imes had four rings, or even five. The inside surface of the ring fits in the groove on the piston. The rings outside surface presses against the cylinder walls.Connecting rod:The connecting rod little end is connected to the piston pin. A bush made from a soft metal, such as bronze, is used for thi

47、s joint. The lower end of the connecting rod fit the crankshaft journal. This is called the big end.Cylinder number and firing order:N.B. No.4 piston is always performing the companion stroke to No.1: when the inlet valve in No.4 cylinder is fully open, No.1 cylinder inlet valve is fully closed - th

48、is feature is useful to remember when checking valve clearances.As each cylinder fires, it causes the crank throw to speed up. The inertia of the rest of shaft cause it to stay slightly behind, resulting in a twisting action on the crankshaft.Inertial ring elastomer The inertia ring is bonded to the

49、 hub through a flexible elastomer (rubber compound insert. The inertial ring moves slightly in relation to crankshaft rotation as each cylinder fires, thereby dampening the torsional vibration of the crankshaft over a wide range of engine speed.Valve operation:The cam is an egg-shaped piece of metal

50、 on a shaft that rotates in coordination with the crankshaft. The metal shaft, called the camshaft, typically has individual cams for each valve in the engine. As the camshaft rotates, the lobe, or high spot of the cam, pushes against parts connected to the stem of the valve. This action forces the

51、valve to move downward. This action could open an inlet valve for an intake stroke, or open an exhaust valve for an exhaust stroke.Valve operation：In this arrangement, the cam lobes push against round metal cylinders called cam follower. As the lobe of the cam comes up under the cam follower, it pus

52、hes the cam follower upward (away from the camshaft. The cam follower rides against a push rod, which pushes against a rocker arm. The rocker arm pivots on a shaft through its center. As one side of the rocker arm moves up, the other side moves down, just like a seesaw. The downward-moving side of t

53、he rocker arm pushes on the valve stem to open the valveValve clearance:When the engine runs in compression stroke and power stroke, the valves must close tightly on their seats to produce a gas-tight seal and thus prevent the gases escaping from the combustion chamber. If the valves do not close fu

54、lly the engine will not develop full power. Also the valve heads will be liable to be burnt by the passing hot gases, and there is the likelihood of the piston crown touching an open valve, which can seriously damage the engine.Valve clearance:So that the valves can close fully some clearance is nee

55、ded in the operating mechanism. This means that the operating mechanism must be able to move sufficiently far enough away from the valve to allow the valves to be fully closed against its seat by the valve spring. However, if the clearance is set too great this will cause a light metallic tapping no

56、ise.Valve timing:It is apparent from this description that the exhaust valve stays open for a short period of time during which the intake valve is also open. In other words, the end of the exhaust stroke and the beginning of the intake stoke overlap for a short period of time. This is called valve

57、overlap. Valve timing and valve overlap vary on different engines.Valve timing:Opening the intake valve before TDC and closing it after BDC increases the fill of air-fuel mixture in the cylinder. Opening the intake valve early helps overcome the static inertia of the air-fuel mixture at the beginnin

58、g of the intake stroke, while leaving the intake valve open after BDC takes advantage of the kinetic inertia of the moving air-fuel mixture. This increases volumetric efficiency.Cam design and control dynamic:The entire valve-train assembly can be viewed as a spring/mass system in which the conversi

59、on from stored to free energy causes forced vibration. Valve-train assemblies with overhead camshafts can be represented with sufficient accuracy by a 1-mass system (consisting of the moving mass, the valve-train assembly stiffness and corresponding damping.Camshaft drive mechanism:Each cam must revolve once during the four-stroke cycle to open a valve. A cycle, remember, c