What is Valve Lift? How valve lift works

Valve lift allows the valve to open wider and let the valve go more into the cylinder, thereby improving engine performance. The principle is the same, but in practice, each brand really has its own magic.

Valve lift is rarely used in actual products, because it is difficult to adapt to the requirements of the change of speed on the intake and exhaust flow characteristics. The engine is more used for variable lift and timing, VLT.

In terms of control effect, variable valve lift technology can be divided into continuous valve lift adjustment (CVVL) and phased valve stroke adjustment (DVVL), both of which have their own advantages and disadvantages.

Valve lift is based on valve timing, in individual working conditions, so that the opening size of the valve is changed, in order to improve engine power or stabilize the speed to reduce emissions, such as less air intake at idle, high speed valve opening is large, more air intake, now the car is also accompanied by valve variable timing, that is, to change the valve opening time, so as to play the same role as changing the lift.

Answer: VTEC system is the full name of variable valve timing and lift electronic control system, is Honda's proprietary technology, it can change with the engine speed, load, water temperature and other operating parameters, and appropriately adjust the valve timing and valve lift, so that the engine can achieve the highest efficiency at high and low speeds. + In the VTEC system, there are three cam surfaces on the intake camshaft, respectively against the three rocker arms on the rocker arm shaft, when the engine is at low speed or low load, there is no connection between the three rocker arms, and the rocker arms on the left and right sides push the two intake valves respectively, so that the two have different timing and lift, so as to form the effect of squeezing.

At this time, the high-speed rocker arm in the middle does not push the valve, but only does ineffective movement on the rocker shaft. When the speed is constantly increasing, the sensors of the engine will monitor the load, speed, vehicle speed and water temperature and other parameters to the computer, and the computer will analyze and process the information. When it is necessary to change to high-speed mode, the computer will send a signal to open the VTEC solenoid valve, so that the press oil enters the rocker shaft and the jacking activity plug, so that the three rocker arms are connected into one, so that the two valves work in high-speed mode.

When the engine speed is reduced to the valve timing and needs to be changed again, the computer sends a signal again to open the pressure of the VTEC solenoid valve, so that the pressure oil is discharged, and the valve returns to the low-speed working mode again.

The principle of the valve is mainly that when the crankshaft rotates, the piston is driven to move up and down in the cylinder, and the camshaft is driven by the chain or belt, and then the flange of the camshaft presses the valve to control the opening and closing of the valve.

The mechanism and technology of valve timing of automobile engines, also known as continuously variable valve timing systems, are commonly equipped with this system in today's high-performance engines. The system is equipped with a control and actuation system that regulates the phase of the engine cam or the valve lift to optimize the engine valve distribution process.

When the engine is at high speed, each cylinder is in a working cycle, and the suction and exhaust time is very short, in order to achieve high charging efficiency, it is necessary to extend the suction and exhaust time of the cylinder, that is, to increase the overlap angle of the valve; At low engine speed, excessive valve overlap angle is easy to cause exhaust gas backfill, and the suction volume will decrease, resulting in unstable engine idle speed and low torque at low speed.

It is difficult for the fixed valve timing to meet the needs of both high and low engine speeds at the same time, so the variable valve timing comes into being. The variable valve timing can be adjusted according to the different engine speed and working conditions, so that the engine can obtain ideal intake and exhaust efficiency at high and low speeds.

The essence of the engine power is actually related to the amount of oxygen entering the cylinder per unit time, and the variable valve timing system can only change the opening and closing time of the valve, but cannot change the amount of air intake per unit time, and the variable valve lift can meet this demand. If the valve of the engine is regarded as a "door" of the house, the valve timing can be understood as the time when the "door" is opened, and the valve lift is equivalent to the size of the "door" opening.

In fact, the engine is the same as our breathing potato, and we need to adjust different breathing rates in different situations. We need to breathe a lot when we are exercising, and we don't need as much air when we are exercising less. The same is true for the engine, which has to adjust its "breathing" frequency and variable valve timing system in different operating conditions.

Valve lift refers to the travel of a valve from closed to fully open. The magnitude of the valve lift is determined by the contour of the valve protrusion and the design of the valve stem and other mechanisms.

The profile of the valve cam is a key factor in determining the law of valve motion and the magnitude of the valve lift. The profile of the valve cam is usually designed according to the engine design requirements and performance requirements. In engine design, the profile of the valve cam needs to be designed according to the requirements of the engine such as speed, power, torque, and emissions to achieve optimal engine performance and emission control.

The radius of the cam is only a parameter of the valve cam profile, which has a certain influence on the size of the valve lift, but it is not the only determining factor. In addition to the cam radius, parameters such as the radius of curvature, slope, and angle of the valve cam also have an impact on the valve lift.

In summary, the valve lift is determined by the design of mechanisms such as the valve cam profile and the valve stem. The design of the valve cam is an important part of the engine design, and the brakes need to be designed according to the engine performance and emission requirements to achieve the best engine performance and emission control.

Valve lift is the vertical displacement distance of the valve during movement, which is one of the important parameters of the valve during the intake and exhaust process of the engine. The valve lift is not determined by the cam radius alone, but by a combination of factors.

In the process of intake and exhaust of the engine, the movement of the valve is driven by the movement of the camshaft, and the shape of the cam and groove on the camshaft determines the movement of the valve. Specifically, factors such as the cam radius of the camshaft, the angle of the cam, and the shape of the curve all affect the lift and opening time of the valves, which in turn affects the intake and exhaust efficiency and performance of the engine.

In addition, factors such as the spring rate of the valve, the valve bearing, and the length of the valve stem also have an impact on the valve lift. Among them, the stiffness of the valve spring is one of the key factors that determine the valve lift, which can effectively control the speed and amplitude of the valve movement.

To sum up, the valve lift is not determined by the cam radius alone, but by a combination of factors. In the process of engine design and manufacturing, these factors need to be considered comprehensively according to different application requirements and operating conditions, and reasonable optimization and adjustment should be carried out to achieve the best intake and exhaust efficiency and performance.

The same is true for variable intake manifold technology, which uses a longer intake manifold at lower engine speeds and a shorter intake manifold when the engine is at high rpm to obtain a larger intake volume in the shortest amount of time.

This will be adjusted as needed.

We need to adjust different breathing rates for different situations. When we are exercising, we need to breathe heavily.

All are to adjust different breathing rates, one is to adjust the height, and the other is to adjust the angle.

Variable valve timing is the adjustment height, and variable valve lift is the adjustment angle.

Variable lift is the opening height of the variable valve.

Variable lift is the opening height of the variable valve, the angle at which the crankshaft opens and closes.

It is the different state of the valve at different times.

Alignment is the angle at which the valve becomes relative to the opening and closing of the crankshaft.

The valve becomes relative to the angle of opening and closing of the crankshaft.

Variable valve lift is the opening height of a variable valve.

Valve lift is on the basis of timing, in individual working conditions, so that the opening size of the valve is changed, in order to improve the engine power or Liang Wushan is to stabilize the speed to reduce emissions, for example, idle when the air intake is less, at high speed the valve opens large, the intake is more rubber, now the car is also accompanied by the valve variable timing, that is, to change the opening time of the valve, so as to play the same role as changing the lift.

Engine fuel consumption can be explained by the movement of a door. The size and length of time the door is open determines the amount of entry and exit. The larger the angle of the door opening, the longer the opening time, the greater the amount of entry and exit, the smaller the angle of the door opening, the shorter the opening time, and the less the amount of entry and exit.

When entering the theater to watch a play, it is necessary to check the tickets of the audience one by one to enter the theater, and the opening angle of the gate must be controlled, and some boxes are also set up with railings, like subway entrances and exits.

To evacuate the audience as soon as possible when the theatre is closed, remove the box railings and leave the doors completely open. The opening angle and time of the door determine the amount, which is very easy to understand. The same Dao Tangerine is used in the engine, and the concept of valve lift and timing is born.

Valve lift is like the angle at which the door opens, and timing is like the time it takes for the door to open. Looking at the problem from a three-dimensional point of view, angle plus time is the size of a volume of space, and its size determines the amount of fuel consumption.

How does the valve work during the intake stroke?

Dear, I will find out that when the piston descends from the top dead center to the bottom dead center during the engine operation, the piston is open and the exhaust valve is closed. When the piston completes the first stroke after going down, to the top dead center is called the compression stroke dust envy, at this time the intake and exhaust valves are patted by Guan Pailing, and then the piston will continue to go down to the bottom dead center, which is called the power stroke, and the valve is still closed when this Wang opens.