Question 2: What is the difference between a balanced shaft ejector engine and a balanced shaft chain machine? Which is better? There is a generation difference in the technical level between the ejector and the chain machine. Chain machine is the next generation product of the development of ejector pin machine, with much higher technical content. The main difference in driving between the thimble machine and the chain machine is that the thimble machine has strong starting ability, convenient maintenance and very strong disaster resistance. The disadvantage is that the valve noise is relatively large, and the tappet will jump at high speed because of the structural limitation of its valve distribution system, resulting in low fuel consumption at high speed. Not suitable for high-speed operation. The ejector is usually called low speed stage.
Chain machine is the next generation product of ejector pin, with low noise, good high-speed performance and much better rapidity than ejector pin machine. The disadvantage is that the start is soft, at least for the ejector with the same displacement, it needs to be rubbed a lot. When I say this kind of kneading, you can also understand that the torque is relatively small. And relatively more troublesome to maintain than the ejector pin machine. In addition, if the quality of the timing chain of the chain machine is not up to standard, it is easy to be stretched, and serious accidents will occur. Therefore, when choosing a chain machine, we must pay attention to the manufacturer of the engine, and buying a famous brand will be guaranteed. In addition, the chain machine is more expensive than the thimble machine. Choose according to your riding needs. Useful to praise. Thank you.
Question 3: What does the balance shaft of the engine do? How to adjust it? Vibration principle of engine working cycle In the working cycle of engine, the speed of piston is very fast and uneven. At the top and bottom dead center, the speed of the piston is 0, and the speed reaches the highest between the top and bottom dead centers. Because the piston makes repeated high-speed linear motion in the cylinder, it will inevitably produce great inertial force on the piston, piston pin and lotus bar, but only part of the moving mass on the lotus bar can participate in linear motion, and the other part can participate in rotation, except for the top and bottom dead points. Every time the piston moves up and down, it will make the engine vibrate up and down twice, so the vibration frequency of the engine is related to the speed of the ground machine. In vibration theory, many simple harmonic vibrations are often used to describe the vibration of ground machines. Among them, the vibration with the same frequency as the engine speed is called first-order vibration, and the vibration with the frequency higher than twice the engine speed is called second-order vibration, and so on. There are also third-order and fourth-order vibrations, but the higher the vibration frequency, the smaller the amplitude. The vibration amplitude above the second order can be ignored, and the first order vibration accounts for more than 70% of the whole vibration, which is the main source of ground vibration.
There are many ways to solve the vibration of engine, such as using light piston to reduce the motion quality and improve the rigidity of crankshaft, and using 90-degree V-type double-cylinder flat engine. But the common method in motorcycle search is to add a balance shaft to solve it. Simply put, the balance shaft is a shaft with eccentric weight, which rotates synchronously with the crankshaft. The anti-phase vibration power generated by eccentric weight can make the engine reach a good balance and reduce the vibration of the engine.
Three, the classification of balance axis has two kinds: double balance and single balance. But the two methods have the same working principle, but the structure is different.
1, double balance shaft mode: Double balance shaft mode drives two balance shafts to rotate through chain drive, in which one balance shaft has the same speed as the engine, which can eliminate the next-order vibration of the engine, and the other balance shaft has twice the speed of the engine, which can eliminate the second-order vibration of the engine and achieve ideal vibration reduction effect. Double-balanced axle mode has complex structure, high cost and large space, so it is only used on motorcycles with large layout at present.
2. The single balance shaft works by gear rotation, and the driving gear of the fixed balance shaft-the driven gear of the balance shaft-the balance shaft is driven by crankshaft rotation. A single balance shaft can balance the secondary vibration, which accounts for a considerable proportion of the whole vibration, and can obviously change the vibration of the geodynamic machine. Single balance shaft method is widely used in single cylinder engines and small displacement engines because of its simple structure and small space occupation.
The main function of the balance shaft is to reduce the vibration of the engine and improve the comfort. Can't adjust, also don't need to adjust. Just install the alignment mark.
Question 4: What is the balance axis of motorcycle? To put it simply, the piston of an engine will vibrate in the process of reciprocating up and down. If the V-type twin-cylinder engine is used, the two cylinders can vibrate with each other, but this will undoubtedly increase the cost of the motorcycle, which is one of the reasons for the large vibration and noise of the single-cylinder motorcycle. For example, if a car uses an engine with more than four cylinders, the engine not only has small vibration, but also can obtain high power without high speed because of the high power of multiple cylinders.
Of course, there is also a solution for motorcycle single cylinder, which is to add a balance shaft to the engine. Simply put, the balance shaft is actually a shaft with eccentric weight, which rotates synchronously with the crankshaft. The reverse vibration force generated by this counterweight can make the engine obtain a good balance effect and reduce the engine vibration.
At present, this technology is very mature, most motorcycle engines use this technology, and some domestic engines also use double balance shafts, so that the ride comfort is better.
Question 5: What is the working principle of the engine balance shaft? First, the vibration principle of the engine
In the working cycle of the engine, the movement speed of the piston is very fast and uneven. At the top and bottom dead center, the speed of the piston is zero, while the speed reaches the highest in the middle of the top and bottom dead center. Because the piston makes repeated high-speed linear motion in the cylinder, it will inevitably produce great inertial force on the piston, piston pin and connecting rod. The counterweight on the connecting rod can effectively balance these inertial forces, but only part of the motion mass of the counterweight on the connecting rod participates in linear motion and the other part participates in rotation. Except for the top and bottom dead center positions, all kinds of inertial forces cannot be completely balanced, which makes the engine vibrate.
Every time the piston moves up and down, the engine will vibrate up and down twice, so the vibration frequency of the engine is related to the engine speed. In vibration theory, many simple harmonic vibrations are often used to describe the vibration of an engine. Among them, the vibration with the same frequency as the engine speed is called first-order vibration, the vibration with twice the engine speed is called second-order vibration, and so on. There are also third and fourth order vibrations. But the higher the vibration frequency, the smaller the amplitude, and the second order or above can be ignored. Its first-order vibration accounts for more than 70% of the whole vibration and is the main source of vibration.
Second, the solution to engine vibration
In order to eliminate vibration, there are many methods, such as using light pistons to reduce the mass of moving parts, improving the rigidity of crankshaft, and using V-shaped double cylinders with an included angle of 90 degrees to arrange the engine. However, the common method in motorcycle engine is to add a balance shaft to solve the problem. Simply put, the balance shaft is a shaft with eccentric weight, which rotates synchronously with the crankshaft. Using the reverse vibration force generated by eccentric weight, the engine can achieve a good balance and reduce the vibration of the engine.
Third, the classification of balance axis
There are two kinds of balance shafts used in motorcycle engines: double balance shaft and single balance shaft. The working principle of the two methods is the same, but the specific structure is different.
1. Double balanced axis mode
Double balance shafts drive two balance shafts to rotate through chain transmission, and one balance shaft has the same speed as the engine, which can eliminate the first-order vibration of the engine; The rotation speed of the other balance shaft is twice that of the engine, which can eliminate the second-order vibration of the engine and achieve ideal vibration reduction effect. Double-sea balance shaft mode is more complicated, with high cost and large engine space, and is generally used on large-displacement motorcycles.
There is also a double balance shaft arrangement mode, that is, two balance shafts are symmetrically arranged at a certain angle with the center line of the cylinder, the rotation directions are opposite, and the rotation speed is the same as that of the crankshaft, so as to balance the first-order reciprocating inertia force of the engine. For example, the balance shaft on the 276Q engine is arranged as above.
2. Single balanced axis mode
The single balance shaft adopts a single balance shaft and works in the way of gear transmission. The fixed balance shaft drives the gear through the rotation of the crankshaft. Balance shaft driven gear-> balance shaft. Single balance can balance the first-order vibration, which accounts for a considerable proportion of the whole vibration and can obviously improve the vibration of the engine. Single balanced shaft mode is widely used in single-cylinder small-displacement engines because of its simple structure and small space occupation.
Fourth, the application of balance shaft
To sum up, the balance shaft is used to balance and reduce the vibration of motorcycle engine, thereby reducing the vibration and noise of the engine, prolonging the service life of the engine and improving the comfort of drivers and passengers. As a patent, it was first used by Yamaha motorcycles and received good results. In the construction of Yamaha, each car series has the application of balance shaft, which is also its characteristic and selling point. It is undoubtedly the quietest of its kind.
Question 6: What is the working principle of the balance shaft in the automobile engine? First of all, we introduce the working principle of the next four-stroke gasoline engine with a single cylinder as an example. We already know that the engine is a machine that converts chemical energy into mechanical energy, and its conversion process is actually the process of working cycle. To put it simply, the fuel in the combustion cylinder generates kinetic energy, which drives the piston in the engine cylinder to reciprocate, thus driving the connecting rod connected with the piston and the crank connected with the connecting rod to reciprocate around the center of the crankshaft and output power. Now, let's analyze this process: a working cycle includes four piston strokes (the so-called piston stroke refers to the process of the distance from top dead center to bottom dead center): intake stroke, compression stroke, expansion stroke (power stroke) and exhaust stroke. Intake stroke During this process, the intake valve of the engine is opened and the exhaust valve is closed. As the piston moves from the top dead center to the bottom dead center, the volume of the cylinder above the piston increases, so that the pressure in the cylinder will be lower than atmospheric pressure, that is, vacuum suction will be generated in the cylinder, so that air will be sucked into the cylinder through the intake pipe and the intake valve, and the atomized gasoline sprayed by the fuel nozzle will be fully mixed with the air. At the end of intake, the gas pressure in the cylinder is about 0.075-0.09MPa, and the temperature of the combustible mixture in the cylinder has risen to 370-400K K. Compression stroke In order to make the combustible mixture in the intake cylinder burn rapidly, thus generating greater pressure and engine power, it is necessary to compress the combustible mixture before combustion, so as to reduce its volume, increase its density and increase its temperature, that is, a compression process is needed. In this process, the intake valve and exhaust valve are closed, and the crankshaft pushes the piston to move from the bottom dead center to the top dead center for one stroke, that is, the compression stroke. At this time, the pressure of the mixture will increase to 0.6- 1.2MPa, and the temperature can reach 600-700 k. There is a very important concept in this trip, that is, compression ratio. The so-called compression ratio is the ratio of the maximum volume of gas in the cylinder before compression to the minimum volume after compression. Generally, the greater the compression ratio, the higher the pressure and temperature of the mixture at the end of compression, and the faster the combustion speed, so the greater the power generated by the engine, the better the economy. The compression ratio of ordinary cars is between 8- 10, but now the latest Polo has reached a high compression ratio of 10.5, so its torque performance is quite good. However, when the compression ratio is too large, not only can the combustion situation not be further improved, but abnormal combustion phenomena such as flashover and surface fire will appear (the influence of fuel quality also occupies a more important position, which we will explain in detail later). Deflagration is an abnormal combustion caused by the high gas pressure and temperature and the spontaneous combustion of combustible mixture at the end far from the ignition center in the combustion chamber. During the explosion, the flame spreads outward at a very high speed, even when the gas has no time to expand, the temperature and pressure rise sharply, forming a pressure wave and advancing at the speed of sound. When this pressure wave hits the combustion chamber wall, it will make a sharp knocking sound. At the same time, it will also cause a series of adverse consequences such as engine overheating, power decline and oil consumption increase. Serious flashover may even cause mechanical damage such as valve burning, bearing bush cracking and spark plug insulator breakdown. Besides flashover, engines with high compression ratio may face another problem: surface ignition. This is another abnormal combustion (also called hot spot ignition or pre-ignition) caused by the mixture being ignited by hot surfaces and hot places in the cylinder (such as exhaust valve head, spark plug electrode and carbon deposit). When surface fire occurs, accompanied by strong knocking sound (dull), it will increase the engine load and reduce the service life. Expansion stroke (power stroke) During this process, the intake valve and exhaust valve are still closed. When the piston approaches the top dead center, the spark plug emits an electric spark to ignite the compressed combustible mixture. After the combustible mixture is burned, a lot of heat energy is released, and the pressure and temperature of the gas rise rapidly. The maximum pressure it can reach is 3-5MPa, and the corresponding temperature is as high as 2,200-2,800 K. The high-temperature and high-pressure gas pushes the piston to stop downward from the top dead center. & gt
Question 7: Do all engines have balance shafts? Some engines are available, such as ea888 of Volkswagen Passat Tiguan and Audi of Ling Du Magotan Golf Express. There are also some engines of Mercedes-Benz and BMW. Mainly to eliminate vibration and make the engine run more smoothly.
Question 8: What is a balanced axle chain machine? It is not a balancing machine.