What are the 3 transmission forms of automobile engine valve mechanism?

The valve train is composed of camshafts, tappets, push rods, rocker arms, rocker arm shafts, valve springs and valve guides and other related components. Camshafts are arranged on the engine with bottom, side and overhead. Modern engines are often overhead-mounted, which is located on the cylinder head.

The camshaft drives the valve directly through the rocker arm, eliminating a large set of reciprocating parts such as tappets and push rods, which is very suitable for high-speed engines, but also brings the difficulty of the transmission shaft, because the camshaft is on the cylinder head, the cylinder head is more troublesome to disassemble and assemble, and the arrangement of the fuel injector is also more difficult. There is also an overhead type in which the camshaft is directly actuated by the spokes of the valve. The advantages of this form are not only simple mechanism, small inertia, and low requirements for camshafts, so it is widely used in new automobiles.

The function of the valve mechanism is to open and close the intake and exhaust valves of each cylinder regularly in accordance with the requirements of the working cycle and firing sequence in each cylinder of the engine, so that the fresh charge can enter the cylinder in time and the exhaust gas can be discharged from the cylinder in time; During the compression and expansion strokes, the sealing of the combustion chamber is ensured. Fresh charge is a combination of gasoline and air for a gasoline engine, and pure air for a diesel engine.

Four-stroke engines usually use a valve-type valve train, which consists of a valve combination and valve transmission group parts. The valve train can be classified from different angles.

Rocker arm drive. Swingarm drive.

Direct drive.

Valve trains can be classified in different ways. Such as according to the valve position, camshaft position, camshaft transmission mode and number of valves. According to the valve position, there are two types of valve trains: overhead type and side-mounted valve system. The side-mounted valve mechanism is gradually becoming obsolete.

According to the position of the camshaft, there are camshaft down, middle and upper gas distribution mechanisms.

According to the camshaft transmission mode, there are gear transmission, toothed belt transmission and chain transmission gas distribution mechanism.

According to the number of valves, there are two valves, three valves, four valves or five valves per cylinder (two camshafts, one for the intake camshaft, the other for the exhaust camshaft) valve mechanism, etc.

There are three main structural forms of transmission mode of diesel engine valve mechanism (gear transmission, chain transmission, and synchronous belt transmission), which are briefly introduced as follows:

1) Gear transmission (Fig. 4-6a).

Suitable for mid-mounted and under-mounted camshafts.

The timing gear is a cylindrical helical gear.

The crankshaft timing gear material is medium du carbon steel, and there are two types: directly machined on the crankshaft and sleeved.

Camshaft timing gears are generally cast iron, but there are also bakelite gears.

2) Chain drive.

Suitable for mid-mounted and top-mounted camshafts.

The chain is a roller chain.

Fitted with chain guides, tensioners and tensioners.

It can maintain a certain tension without generating vibration and noise.

3) Synchronous belt drive.

1 Suitable for upper dao mounted camshafts.

Car engines or small diesel engines are mostly used.

The elongation is small, and the version is suitable for precise timing transmission rights.

Low noise, light weight, low cost, reliable operation, no lubrication.

It cannot be in contact with water and oil, and it is easy to skip teeth.

It can maintain a certain tension force, and a tensioner and tensioner are required.

Among the three transmission modes of the valve mechanism, for large and medium-sized diesel engines, gear transmission is used more; For small diesel engines, chain or synchronous belt transmission is used more. Hope to get yours, thanks.

Advantages and disadvantages of the transmission mode of the valve mechanism (1) Gear transmission: (1) Advantages: accurate gas distribution phase, good working reliability and durability.

2) Disadvantages: large noise, wear, difficult space layout, and large weight. Helical teeth are generally used to improve the stability of work.

2) Chain drive: (1) Advantages: large degree of freedom in space layout, strong adaptability to model changes, low manufacturing cost, reliable work, and convenient maintenance.

2) Disadvantages: the chain is easy to relax, must be equipped with a tensioner, the gas distribution phase is easy to change, it needs to be adjusted regularly, the noise and wear are large, and the durability is poor. (3) Toothed belt drive:

1) Advantages: The main advantages of Douqing gear transmission and chain transmission (accurate gas distribution phase, but to solve the problem of belt relaxation; Large degree of freedom in space arrangement; low wear and tear). (2) Disadvantages:

Poor working reliability, poor limb durability, high friction resistance, and fear of engine oil.

1. Composition of valve mechanism: The valve train is composed of two groups: valve transmission group and valve group, valve transmission group includes crankshaft timing gear, camshaft timing gear, camshaft, tappet, push tung slow rod good knowledge, hosiery mold rocker arm, valve clearance adjustment screw and lock nut, rocker arm shaft, valve group including valve, valve guide, valve spring, valve spring seat, valve seal, valve seat, etc. Second, the working principle of the gas distribution mechanism:

When the camshaft rotates, when the base circle part of the cam is in contact with the tappet, the tappet does not rise, the transmission parts above the tappet do not act, and the valve is closed. When the protrusion of the cam comes into contact with the tappet, it starts to jack up the tappet and the valve is opened. When the maximum bulge of the cam comes into contact with the tappet, the valve reaches its maximum opening.

Subsequently, the bulge on the contact surface between the cam and the tappet begins to gradually become smaller, the valve begins to rise and close under the action of the valve spring, and the transmission rod such as the rocker arm is pushed in reverse to keep the tappet in contact with the cam. When the cam bulge leaves the tappet, the valve closes completely.

The transmission of the valve mechanism has gear transmission, belt transmission and paper strip.

1.Gearing. Most of the gas distribution mechanism of the summer solstice of the dragon slaying shaft adopts cylindrical timing start, generally from the crankshaft to the camshaft to transmit the stove only need a pair of timing gears, if necessary, the intermediate gear can be added to check the scan, in order to mesh smoothly and reduce noise, the timing gear is more than helical teeth.

Sprockets, sprockets are generally used in the exhaust mechanism of the camshaft top.

Synchronous drive transmission.

In the process of driving, the engine plays a very important role, if there is an abnormality, it will affect the safety during driving. However, few car owners have a deep understanding of the composition of the engine valve structure. So what is the composition of the gas distribution mechanism of the start-up Zhizhi quiet machine?

The engine valve train is mainly composed of two parts: the valve transmission group and the valve group. The valve transmission group mainly includes timing gears, valve push rods, adjusting screws, rocker arms and brackets, tappets and camshafts, etc. The valve group is mainly composed of valve locks, valves, valve seats and valve guides, valve springs, etc.

Their main role is to drive the opening and closing of the valves.

In addition, the valve mechanism is the engine cylinder in the working process, plays a very important role, through the timing of opening and closing the intake valve, exhaust valve, can make the fresh combustible gas mixture into the cylinder in time, while promoting the exhaust gas to be discharged from the cylinder in time, it is very helpful to improve the transmission efficiency of the engine.

1.The valve mechanism of the engine includes camshafts, tappets, push rods, rocker arms, rocker arm shafts, valve springs, valve guides, etc.

2.The valve mechanism of the engine opens and closes the intake and exhaust valves of each cylinder regularly according to the requirements of the working cycle and ignition sequence of each cylinder of the engine, so that the fresh combustible mixture or air and vertical field enter the cylinder, and the waste gas is discharged from the cylinder in time.

3.A starter is a machine that converts other forms of energy into mechanical energy, including internal combustion engines (reciprocating piston engines) and external combustion engines (Stirling engines, steam engines, etc.). ).Jet engines, motors, etc.

It is determined by each cylinder, the cycle of work, the order of ignition, the function of each part running, and the mechanism of gas distribution is also in order.

Hello, I am a master with decades of experience! I've seen your problem! I will reply to you within five minutes, and after answering, if you are satisfied, can you give me a thumbs up? Thank you!

Hello, 1. The valve mechanism can be divided into two parts: valve group and valve transmission group.

2. The valve group includes the valve and its related parts, and the composition of the valve group has nothing to do with the form of the valve mechanism, 3. The valve transmission group is all the parts from the timing gear to the valve action, and the valve transmission group mainly includes the camshaft timing gear, tappet, and the rocker arm and rocker arm shaft of the guide pusher.

The valve train is composed of two groups: valve transmission group and valve group, valve transmission group includes crankshaft timing gear, camshaft timing gear, camshaft, tappet, push rod, rocker arm, valve clearance adjustment screw and lock nut, rocker arm shaft, valve group includes valve, valve guide, valve spring, valve spring seat, valve oil seal, valve seat, valve seat, etc.

Mainly there are gears, tappets, push rods, camshafts, rocker arms, valve clearance adjustment screws, rocker arm shafts, valves, valve tube valves, spring valves, spring seats, nuts.