What Is an Exhaust Duct?

The exhaust pipe is a part of the exhaust system of the engine. The exhaust system mainly includes an exhaust manifold, an exhaust pipe and a muffler. Generally, the three school catalysts for controlling engine pollutant emissions are also installed in the exhaust system. The pipes generally include a front exhaust pipe and a rear exhaust pipe.

Chinese name: exhaust pipe

Foreign name: Exhaust pipe

Exhaust pipe introduction

Exhaust pipe back pressure exhaust pipe

(It is more environmentally friendly as the original factory) The principle is the same as the original factory, but the sound will be better than the original factory. Most of the original cars use this kind of tube, which mainly depends on the grid muffler or the volume change of the tube to produce a kind of Returning to the cylinder pressure, when the engine is ignited, the piston begins to move forward, and the exhaust valve will open before the piston reaches the bottom dead center. At this time, the back pressure in the tube will block the exhaust gas from rushing out, so that the mixture can reach complete combustion. However, if the back pressure is too strong, the exhaust gas cannot be completely discharged from the cylinder, which causes the exhaust gas to burn with the mixture to reduce the combustion efficiency. Of course, the most direct is to spur the horsepower output. Its advantages: low noise and good low-speed torque. Disadvantages: exhaust gas cannot be quickly discharged at high speeds, which affects engine power output and has low volume.

Exhaust pipe half return pressure pipe

Of course, the power of this kind of pipe back pressure is low, and the exhaust pressure is better than the back pressure pipe. To put it simply, he has a moderate back pressure between the back pressure pipe and the straight pipe to obtain the starting torque. The degree is better than the back pressure pipe, of course, the torque at medium and high speed is also greater than the back pressure pipe. Advantages: good torque performance at start and end. Disadvantages: high noise and loud volume.

Exhaust pipe straight

Acceleration will be better than the return pressure tube, but the biggest disadvantage is that it is very noisy. It will make "Uncle Police" chase you. The return pressure is very low, the exhaust has no resistance, the low-speed torque is poor, and the middle-high speed torque is large . Advantages: smooth exhaust, strong torque at high speeds. Disadvantages: soft power at low speeds, and high noise (some people say that it is easy to burn the valve. I do nt know if it is true). The volume is too large.

Exhaust pipe semi straight

In fact, the semi-straight pipe is the same as the half-return pipe, but the exhaust diameter is larger than that of the half-return pipe: the starting torque is lower than that of the half-return pressure, but the torque at medium and high speed is large

Variable exhaust pipe

Exhaust is controlled by a valve for optimal sound and performance.

Exhaust pipe design type

S-drum: Increases torque at low and medium speeds, and starts quickly. Strong climbing. The sound is low. At about 90 dB, the high-speed horsepower will not be sacrificed, and the formation of the three wastes is mainly extended to achieve the role of power improvement. (Disadvantage: there is resonance sound at high speed, there is not much improvement for high speed horsepower), S drum is used for engines with displacement below 2.0.

Internal back pressure: Specially designed according to the characteristics of its own car. Increase the torque at low and medium speeds, and the sound is not loud. No resonance sound. There is no resonance sound at high speeds, and the speed is fast. (Sound is similar to S drum. Some models cannot be equipped with S drum, only internal pressure can be installed.)

Type G: For engines with a large displacement of 2.0 or above, the sound can be reduced by 3 times of back pressure, and the form of air flow is extended. Similar to S drum. The sound is around 90 dB xiex. Increased torque at low and medium speeds (S drum for small displacement cars below 2.0. G drum for large displacement cars above 2.0)

Straight: Increase the horsepower at high speeds, and the torque at low and medium speeds will not increase much. More suitable for long-term running high-speed and racing track. The sound is around 100 dB. Noisy.

Y type: increase torque at low and medium speeds. Noisy. Around 95 dB

Street Drum: It improves the horsepower and torque, and the sound quality is quite particular. The drum body is completely designed to increase horsepower and reduce the volume. It can be used in streets and high-speed walking. The exhaust of the entire section is the most popular in Japan. Design style: 47mm-63mm-76mm, 63mm and 76mm are connected by a back pressure pipe, which can better display the engine's potential. The sound is around 90 dB, which balances the fuel consumption acceleration response and power increase. Street drum has become an ideal street. Walking Throat, (The appearance of the street drum is beautiful, it is baked in black, and the performance of the car is very good.)

M drum: Variable back pressure design. Adjust the back pressure according to the speed. There is no resonance sound at high speed. When the engine is at low speed, the gas flow speed is slow and the speed through the regulating valve will change. Slow, the vacuum produced is small, the suction force is small, and the back pressure of the exhaust gas stored in a unit time is large. When the engine is at a high speed, the gas flow speed is fast, and the speed of the valve through the control valve will be faster, a large vacuum will be generated, and a large amount of exhaust gas will be eliminated, and the high-speed exhaust gas will be smooth. It achieves the effect of increasing the torque and increasing the horsepower. (Full-speed power) The high speed is about 85 decibels. It is the most obvious and power-exhaust exhaust pipe in China at present according to foreign design concepts. At 2500-3000 rpm The sound came out, and it quieted again at 4,000 rpm.

HKS type: It is in-line with back pressure, which improves the low and medium speed torque and high speed horsepower. The sound is smaller than the straight line, louder than the back pressure, and more crisp, it will not disturb at 95 decibels. No resonance at high speeds. (With the effect of Japanese HKS) Design principle: The airflow runs along the wall.

Middle section: It is used to connect the head focus and the tail section, and it can also improve the horsepower by 3-4 horses.

Design Issues on Motor Vehicle Exhaust Pipe Angle

The exhaust angle of motor vehicle exhaust pipe has always been a difficult problem for professional manufacturers. According to the survey, the angle direction of the exhaust pipes of cars and light household cars is generally backward parallel to the ground, while the angles of the exhaust pipes of high-powered transport vehicles and agricultural vehicles are folded to the ground. From the perspective of environmental protection, according to the current angular design and mechanical design principles of the exhaust tailpipes of motor vehicles, no new angular displacement design method has been specified. The optimal design plan for all vehicle exhaust emission angles should be 180 degrees parallel to the ground to face the rear of the vehicle. If the design plan is not uniform and standardized, the random design of the exhaust pipeline direction by various manufacturers will be detrimental to environmental protection and will occur during driving Unexpected infringement. 1. The disadvantage caused by the angle of the exhaust pipe folded to the ground at about 45 degrees.

In this range of emission angles, when the car is running, the high-velocity exhaust will blow up the dust on the ground, and the faster the driving speed, the greater the degree of pollution caused by the dust. At the same time, the greater the power of the car, the greater the flow and velocity of the discharged gas, and the higher the pollution level of its dust. According to market surveys, the areas with the most serious dust pollution should be the sections along the highway. The more traffic, the more serious the dust will be. On the other hand, dust pollution is also related to the cleanliness of the highway ground surface. The more dust on the highway ground surface, the greater the amount of dust blown up by automobile exhaust.

2. There is also a problem with the angle of the exhaust pipe to the sides of the car.

If the angle of the exhaust pipe is folded to both sides of the car, the exhaust of the car while driving will cause impact injury to the pedestrian due to the hot airflow. In addition, automobile exhaust contains unburned atomized oil stains, which include pollutants such as sulfides and carbides, which can cause human infringement.

3. When the angle of the exhaust pipe is folded upward, it will cause serious damage to the car body.

Car manufacturers generally do not choose this kind of angle folding. Because pollutants such as sulfides and carbides in the exhaust gas will chemically corrode metal parts such as automobile bodies, manufacturers generally do not choose this exhaust emission angle.

According to the relevant provisions of China's Environmental Protection Law, the machinery industry management departments in various provinces, municipalities and regions should work out uniform standards for the angle fold of fuel vehicle exhaust pipes, preferably parallel to the ground and discharging backward. And strictly prohibit the implementation of the design of the exhaust pipe to the ground and both sides to reduce the dust pollution generated by motor vehicles while driving and increase the environmental protection regulations of the operation management mechanism, so that our sky is clearer and the environment is better.

exhaust pipe

Exhaust pipe faq

Exhaust pipe drainage

Water dripping from a car's exhaust pipe is a good sign. It proves that your car's engine is fully burned, and the car's exhaust pipe will drip water outwards. In fact, this is a very normal phenomenon and has nothing to do with the exhaust pipe.

The reason why the exhaust pipe drips water is that carbon dioxide and water are generated after the car gasoline is completely burned. At high temperatures, the water becomes water vapor. At high temperatures, the water vapor is colorless and transparent. Will condense into water. If the condensed water droplets are small and suspended in the air, the water vapor will appear as a white gas, but when the temperature is low, the white smoke from the exhaust pipe is water vapor; It became water. The water droplets discharged from the exhaust pipe are the water vapor generated after the gasoline is burned and condensed in the exhaust pipe and the muffler. However, when the ambient temperature is high, the water vapor is discharged without condensation. When the temperature is low, water vapor will condense into water droplets on the exhaust pipe wall and flow out with the exhaust gas. This phenomenon is relatively normal in most cars.

For a lot of cases, there may be water accumulation in the exhaust pipe at this time. So it is recommended that you go to the store where you purchased it, and it is free if there is a warranty.

Exhaust pipe

After starting the diesel engine, the exhaust pipe emits a lot of off-white smoke.

Failure analysis:

This failure is generally caused by the diesel injected into the cylinder being discharged without fire or the combustion chamber entering the cooling water.

cause of issue:

1 Injector of individual cylinders has poor injection atomization.

2 Low fuel injection pressure.

3 There is serious oil dripping from the fuel injection nozzle.

4 The ambient temperature is too low, resulting in no combustion or poor combustion of individual cylinders.

5 Moisture in diesel.

6 Water droplets have penetrated into individual tanks.

7 Fuel advance angle is incorrect.

Troubleshooting method:

For this kind of failure, use the cylinder-break method to judge, and check the abnormal cylinders and damaged parts by checking the oil-break from cylinder to cylinder.

1 First start the diesel engine to a speed of about 700r / min, and then check the oil cut off cylinder by cylinder. When the high-pressure oil pipe of the second cylinder was disconnected, it was observed that the exhaust smoke changed from the original off-white smoke to a large amount of white smoke, which indicated that there was a malfunction in the second cylinder.

2Remove the injector of the second cylinder, and then check its injection pressure and the atomization quality of the injection, and find that the nozzle of the injector is leaking. After replacing the parts, restart the diesel engine after assembly, observe the smoke exhaust situation, and find that the smoke exhaust situation has changed from the original gray smoke to a large amount of white smoke. an examination.

3 After stopping, when removing the cylinder heads, there are four nuts in the cylinder heads of one, two, and two cylinders that are twisted with a torque of 100 N · m, and the cylinder head nuts become loose. This situation is due to the tightness of the cylinder pads, resulting in water in the combustion chamber.

4 After tightening again with a torque of 280N · m as required, after starting the diesel engine for 5 minutes, the white smoke from the exhaust pipe disappeared, and the fault was eliminated.

exhaust pipe

Diagnostic processing

When the engine starts, a large amount of white smoke is emitted from the exhaust pipe, which is generally not a malfunction of the fuel supply system.

_ Reason

_ Diesel has water, which evaporates into water vapor in the cylinder and is discharged from the exhaust pipe.

_ The cylinder head bolts are loose or the cylinder gasket is damaged, so that the cooling water enters the cylinder.

_ There is trachoma or cracks somewhere in the cylinder block or cylinder head, and water enters the cylinder to evaporate and discharge.

_ Diagnosis and treatment

Approach the outlet of the muffler of the exhaust pipe with your hand. If there is water droplets on the wet hand, confirm that water has entered the cylinder.

Check whether there is water in the diesel oil. Check whether there is a large amount of water in the oil-water separator. If there is a large amount of water, the fuel quality is poor. First remove the water in the high and low pressure oil circuits; then open the drain plug of the fuel tank to release the water in the fuel tank, and finally flush the fuel tank with clean diesel.

Open the water tank cover and press the starter button while observing whether the water surface of the water inlet is bubbling.

If there is water in the oil, or air bubbles appear on the water surface of the water inlet, the cooling water has entered the cylinder.

Before removing the cylinder head, check the tightness of each bolt. If there are loose bolts, tighten them and check whether there is water leakage. If the water still leaks, proceed to the next inspection.

To further find the specific leaking part, you can inflate the water tank with a pressure not greater than 200kPa, open the oil pan, and check the leaking part at the bottom of the engine; then open the cylinder head to see the bottom of the cylinder head and the cylinder pad, and check the faulty part. For parts leaking into the cylinder, take the method of repairing or replacing the new assembly.

Fault judgment

Judging the failure of diesel engine exhaust smoke: The diesel exhaust pipe normally emits colorless gas. If the exhaust pipe emits black, white, or blue smoke, it means that the engine is faulty, and the exhaust emissions are Affecting the surrounding environment is also a warning to the user, and the failure of the engine must be eliminated in time. In the following, Xinghuo diesel generator repair manufacturers will give you several scenarios of generator smoke for your reference.

Black smoke from trachea

Analyze the cause of the failure:

(1) The air filter is severely blocked.

(2) The injection time is too late.

(3) The fuel injector is faulty or the newly installed fuel injector has the wrong model.

(4) The fuel injection pump is faulty or the smoke limiter (or booster compensator) is not adjusted properly.

(5) Supercharger failure.

(6) Intercooler malfunction.

(7) The exhaust brake valve is in the closed position.

(8) Insufficient cylinder pressure.

Judgment and exclusion method:

The reasons are discussed as follows:

(1) Before checking the exhaust pipe for black smoke, remove the air filter. If the black smoke disappears from the diesel engine, it means that the air intake is insufficient due to the serious blockage of the air filter and the black smoke is caused. At the same time, you should also check whether the air intake pipe is blocked, such as the air intake hose sucks flat.

(2) Excessive fuel supply from the fuel injection pump or too uneven fuel supply from each cylinder will also cause black smoke from the exhaust pipe. Therefore, the fuel supply from the fuel injection pump must be readjusted. If the smoke limiter is not adjusted properly, it will also cause black smoke in the exhaust pipe. Adjusting the smoke limiter adjustment screw outwards can reduce the amount of smoke, but excessive adjustment will cause the engine to become weak.

(3) Severe wear of the compressor impeller or turbine of the supercharger will reduce the amount of intake air, causing black smoke from the exhaust pipe. Exhaust pipe mats or supercharger interface mats cause serious air leakage, which will also cause insufficient air intake, black smoke from the exhaust pipes, or reduced engine power.

(4) The poor heat dissipation of air-to-air-cooled intercooler will reduce the intake air volume and the exhaust pipe emits black smoke. Therefore, in the routine maintenance, the intercooler should be cleaned frequently to keep it open.

(5) If the exhaust brake valve is in a closed state, the exhaust pipe will emit a large amount of black smoke, and the engine will accelerate poorly and become weak.

(6) Insufficient compression pressure of the cylinder is one of the main reasons for black smoke from the exhaust pipe.

If the cylinder pressure is insufficient, after the engine starts, off-white smoke will be emitted at first, which will change to black smoke as the temperature of the diesel engine rises.

Xinghuo diesel generator repair manufacturers analyzed the main causes of insufficient cylinder pressure:

(1) Excessive or no valve clearance;

(2) The valve seat is not tightly sealed;

(3) The gap between the piston and the cylinder is too large; the piston ring loses elasticity or breaks and leaks too much air;

(4) The camshaft is severely worn, resulting in insufficient air intake and poor exhaust. To check the camshaft's wear, use a 10mm dial gauge to measure the valve lift. If the wear is severe, it must be replaced.

2.Exhaust pipe emits white smoke

Analyze the cause of the failure:

(1) There is water in the oil, or water in the cylinder is caused by the cylinder gasket being washed out, the cylinder liner or the cylinder head being broken and leaking.

(2) The camshaft of the fuel injection pump of individual cylinder is severely worn, which makes the cylinder injection time lag too much, diesel cannot be completely burned in the cylinder, and the exhaust pipe will emit white smoke.

(3) Poor atomization of the fuel injection nozzle or more than one gasket is installed under the fuel injection nozzle. Therefore, when replacing the fuel injection nozzle, remove the copper pad inside.

(4) The water-cooled intercooler leaks water, and the cooling water enters the cylinder from the intake pipe.

(5) The seal ring of the turbo end of the turbocharger is not tight, and the engine oil is directly discharged from the exhaust pipe, forming "white smoke" in the exhaust pipe. If the exhaust pipe emits severe white smoke, you must carefully check the turbocharger for oil leakage when checking other parts is normal.

(6) The temperature is too low, and the temperature of the cylinder is difficult to rise, especially when the engine starts to emit white smoke in the morning, it turns to blue smoke after warming the car, and it becomes colorless soon. This is normal and should be distinguished from the fault .

(7) When the vehicle is running, if the engine suddenly becomes weak, the exhaust pipe emits a lot of white smoke, which is usually caused by the late fuel supply time.

The main reasons for analysis are: the coupling screws on the fuel injection pump coupling are loose or the steel sheet is broken; the air compressor shaft is broken; the fuel injection pump shaft is broken.

3. The exhaust pipe emits blue smoke

The formation of blue smoke: the engine oil enters the combustion chamber and is discharged from the exhaust pipe.

Analyze the cause of the failure:

(1) The oil seal of the intake valve is not tight, and the oil enters the combustion chamber for combustion.

(2) The piston ring loses its elasticity or breaks; the cylinder liner is severely worn, and the oil penetrates into the combustion chamber. In this case, the exhaust pipe generally has a large amount of exhaust gas.

(3) The seal ring on the impeller end of the turbocharger compressor is not tightly sealed, and the organic oil enters the combustion chamber of the cylinder for combustion.

The above are some suggestions given by Xinghuo on generating unit smoke. For specific questions, you can call Xinghuo diesel generator repair manufacturers or log in to the company's website. Spark mainly undertakes medium, large and small repairs and maintenance of various generator sets.

Exhaust pipe maintenance

Exhaust pipe method

1. When it is difficult to start a cold car in winter, close the choke valve to start the engine. After warming the car, pay attention to opening the choke valve in time. Prohibit driving at high speed for a long time with the choke closed;

2. It is forbidden to install windshields or other decorative items in front of the engine and muffler on riding vehicles (men's vehicles), which will affect the heat dissipation of the engine and muffler;

3. Do not drive for a long time with large load and low gear, this will cause damage to the engine and muffler;

4. Do not bomb the throttle at high speed in situ for a long time;

5. When there is oil stain on the surface of the muffler, the surface color of the muffler will turn yellow and blue after heating. In addition, when there is a large amount of dirt such as dirt on the surface of the muffler, please clean it in time to avoid affecting its heat dissipation;

6. When installing the muffler, pay attention to the installation of the muffler pad and fasten it to prevent air leakage, affect the muffler effect and cause yellowing at the muffler interface;

7. The engine valve clearance, carburetor, air filter, etc. should be adjusted and cleaned in a timely and correct manner according to the vehicle's instructions. If the valve clearance is too small or the mixture is too rich or too lean, it will affect the combustion and affect the muffler. Cause discoloration.

Exhaust pipe tips

Car exhaust pipe maintenance tips 1: waterproof

When driving or washing the car on a rainy day, you must pay attention to prevent the muffler from getting into the water, otherwise it may easily cause rust and affect the use of the exhaust pipe; if the muffler is not getting into the water, start the engine hot car immediately, as far as possible It is especially important for the maintenance of the exhaust pipe to allow the accumulated water in the muffler to drain out.

Car exhaust pipe maintenance skills 2: antirust

The rust prevention of automobile exhaust pipes is not only water-proof, but the best way is to rub some rust-proof oil, so that it can be more comprehensive. We first remove the muffler, plug the drainage hole in the ground, then give the flange a rust-proof oil, then shake the muffler to know that the rust-proof oil has evenly entered the barrel, and then install the muffler. Then, after the car has traveled for about twenty kilometers, you can remove the blockage from the drainage hole. The rust prevention of automobile exhaust pipe maintenance can be largely protected from rusting about twice a year.

Car exhaust pipe maintenance skills 3: cleaning

Since the exhaust pipe is often exposed, but it is the same as the interior of the car, if the exhaust pipe is full of dirt, it will also affect the normal use of the exhaust pipe, and other harmful substances may enter the car due to improper driving Within, and cause other bigger problems, it also happens from time to time. Therefore, in the maintenance of automobile exhaust pipes, we must also pay attention to the cleaning of exhaust pipes. ^[1]