525 履帶拖拉機(jī)變速器改進(jìn)設(shè)計Ⅰ（有cad圖）,525,履帶拖拉機(jī)變速器改進(jìn)設(shè)計Ⅰ（有cad圖）,履帶,拖拉機(jī),變速器,改進(jìn),改良,設(shè)計,cad Sensors and automatic transmissions Sensors in a modern fuel injection system there is an eletronic control unit some car manufactures call it a ECU or other things . Generically we call it the brain,since it does the “thinking”.NOW comparing it to the human boby will help you understand how it works. Your brain receive information from your sense : sight touch taste, smell and hearing. Since a computer doesn’t have hands , eyes , ears or noses they need to get information some how. That’s where sensors come in .These sensors are the eyes and ears of the ECU. As the information comes in, the ECU processes it and determines what output to use to do something. Here are some of there input sensors and how they work Mass Air Flow Sensors The mass airflow rate by measuring a part of the entire intake flow. It consists of a hot wire that is supplied with electric current from the ECM. The temperature of the hot wire is controlled by the ECM a certain amount. The heat generated by the hot wire is reduced as the intake air flow around it. The more air, the greater the heat loss. Therefore, the ECM must supple more electric current to maintain the temperature of the hot wire as airflow increases. The ECM dectects the airflow by means. of this current change. Intake Air Temperature Sensor The intake air temperature sensors is mounted to the air duct housing. The sensor detects intake air temperature and transmits a signal to the ECM. The temoerature—sensing unit uses a thermistor that is sensitve to the change in temperature. Electrical resistance of the thermistor decreases in response to the temperature rise. Crankshaft Position Sensor The camshaft position sensor monitors engine speed and poston position .These input signal to the ECM are used to control fule injection, ignition timing and the other functions. Coolant Temperature Sensor The engine coolant temperature sensor is used to detect the engine coolant temperature. The sensor modifies a voltage signal from tne ECM, The modified signal returns to the ECM as the engine coolant temperature input .The sensor uses a thermistor that is sensitive to the changd in temperature .The electrical resistance of the thermistor decreases ae temperature increases. Knock Sensor The knock sensor is attached to the cylinder block. It senses engine knocking using a piezoelectric element. A koncking vibration from the cylineder block is sensed as virbrational pressure. This pressure is conveerted into a voltage signal and sent to the ECM. Heated Oxygen Sensor It is placed into the exhaust manifold It detects the amount of oxygen in the exhaust gas compared to the outside air. The sensor has a closed—end tube made of ceramic zirconia. Thorttle Position Sensor The throttle position sensor responds to the accelerator pedal movement. This sensor is a kind of potentiometer the throttle position into output voltage, and emits the voltage signal to the ECM. In addition, the sensor detects the opening and closing speed of the throttle valve and feeds the voltage signal to the ECM. The ECM receiving the signal from the throttle position sensor determines idle position of the throttle valve. Vehicle Speed Sensor The vehicle speed sensor is installed in the transaxle It contains a pulse generaor that provides a vehicle speed signal to the speedometer. The speedometer then sends a signal to the ECM. Parking Sensor The system is automatically activated when the driver engages reverse gear. Small sensors are fixed to the rear of the vehicle, and they send and receive ultrasonic radio waves which bounce off obstacles and alert the driver to their presence.There is an internal buzzer that gradually increase in frequency as the drive approach the object. A continuous tone denotes that the car is within 0.35m of the obstacle. Now not all engine have all of there sensors .The ones listed here are the most directly responsible for proper fuel management. Automatic Transmissions The modern automatic transmission is by far, the most complicatef mechanical component in today’s automoblie. Automatic transmissions contrain mechanical systems ,hydraulic systems ,electrical systems and computer controls ,all working together in perfect harmony which goes virtually unnoticed until there is a problem. What is a transmission? The transmission is a drive that is connected to the back of the engine and sends the power from the enginge to the drive wheel. An automobile engine runs at its best at a certain RPM(revolutions per minute) range and it is the transmission’s job to make sure that the power is delivered the engine within that range. It does this through various gear combinations. There are two basic types of automatic transmissions based on whether the vehicle is rear wheel drive or front wheel drive. On a rear wheel drive car ,the transmission is uaually mounted to the back of the engine and is located under the hump in the center of the floorboard alongside the gas pedal position.A drive shaft connects the rear of the transmission to the final driver which is located in the rear axle and is used to send power to the rear wheel . Power flow on this system is simple and straight forward going from the engine, through the torqu converter , then through the transmission and drive shaft until it reaches the final driv where it is split and sent to the two rear wheels. On a front wheel drive car, the transmission is usually with the final drive to form what is called a transaxle. The ehgine on a front wheel drive car is usually mounted sideways in the car with the transaxle tucked under it on the side of the engine facing the rear of the car. Fornt axles are connected directly to the transaxle and provide power to the front wheels In this example, power flows from the engine, through the torque converter to a large chain that sends the power through a 180 degee turn to the transmisson that is along side the engine. From there , the power is routed through the transmission to the final drive where it is split and sent to the two front wheels through the drive axles. Transmission Components The mode automatice transmission consists of many components and systems that are designed to work together in a sysmphony of clever mechanical, hydraulic and electical technology that has evolved over the years into what many mechanically inclined individuals consider to be an art form. The mian components that make up an automatice transmission include: Planetary gear sets which are the mechanical systems that provide the various forward gear rations as well as reverse. The hydraulic system which uses a specical transmission fiuid sent under pressure by an Oil Pump thourgh the Valve Body to control the Clutches and the Bands in order to control the planetary gear sets. Seals and gaskets are used to keep the oil where it is supposed to be and preven it from leaking out. The torque converter which acts like a clutch to allow the vehicle to come to a stop in gear while the engine is still running. The Future Car The future car, let’s say a 2025 model will be a very different machine to its present day grandfather. They will be cheaper to run, cleaner for the environment, packed with computers and safety devices ensuring that not even a stunt driver can crash, and they will run on carbon dioxide and emit strawberry scented oxygen. Well they might be such in the future: Computing and Communications Today, the internet in a few cars; tomorrow, broadband in all of them. Any capability a personal computer has, a car will have, including two-way wireless communications for receiving e-mail, music, and movies. When you’re crossing the Grand Canyon, the kids can learn about the rock formations or watch TV if they’re bored. Every passenger will have a flat-panel display and audio/video feed. The car will broadcast developing problems and route you to the nearest dealer stocking the repair parts. Navigation and Self-Driving every car will have a navigation system linked to GPS satellites. Laser, ultrasound, or radar sensors will track nearby cars. On the freeway, they’ll slow your car when the car ahead of you slows; in town, they’ll help you park without smacking the car behind. At rush hour, you’ll get alternate routes around jams and accidents. Lane-marking emitters embedded in the roadway or in–car video cameras may make it possible for the car to drive itself——though some say that’s 30 to 40 years off. Environment and Emissions Motor vehicles today represent 20 to 30 percent of the world’s energy consumption and emissions. In the near term, hybrid powerplants combining a small gasoline engine and an electric motor will top 50 miles per gallon. Braking will regenerate electricity in a storage battery. Longer term, cars might burn zero-emission hydrogen or use a fuel cell that converts a fuel like hydrogen and combines it with oxygen to create electricity. The exhaust will be pure water. Virtually all car parts will be recyclable. Driving Experience Dashboards will have only a handful of knobs and switches. You’ll use speaker-independent voice control:“Make it a bit cooler”, “Find me country music”. The steering wheel could evolve to paddles or a lever. Lighter, more reliable electronic controls (throttle, brakes) replace mechanical controls. Fiber optics and LEDs replace electrical wires and light bulbs. Seats will be ventilated and air-conditioned. LCD elements will darken windows on sunny days. The car will bank into turns, just as an airplane does now. Safety Cars will avoid some accidents by maintaining safe following distances, limiting skids, and sensing sleepy or inebriated drivers. If you cross over a divider lane without using your blinker (you may be getting sleepy), steering wheel feedback will emulate rumble strip to alert you. In the future car designers will have to explore new themes and find alternative influences for their designs .In an effort to catch peoples eye the designs will have to be increasingly bold and brash often sacrificing the aesthetic balance of the design in attempt to be different in an increasingly “done before” market. New materials are constantly brought into the automotive field, sensors will monitor the cars’ position on the road and if the vehicle is found to be straying from the road or traffic lane an alarm would sound. Sensors could also monitor the drivers’ well-being, tracking eye movement and if the eyes close for more than a few seconds an alarm would sound to alert the driver. The interior of vehicles will also change, becoming more user friendly and personalized. Ergonomically positioned controls and lumbar support seats with adjustable everything will come as standard to increase driver and passenger comfort and reduce chronic pain and discomfort. Passenger safety is already a priority for modern day car manufacturers and this will only increase in importance into the future .The widespread use of airbags will increase, and the side impact protection airbags featured in some models have proved to be extremely effective in saving lives, but more research and better positioning will continue to improve their performance and reliability. Multimedia systems will continue to develop in cars until the point where the “are we there yet” phrase develops into“can we stay here”. The sound systems of cars will also improve and become more personalized for the various passengers, with headphone sockets and multiple sound outlets, there might be four different radio stations that can b e played at once through the different jacks, and a variety of MP3s that can be played at once. These will be the future cars, well they might.