Danfoss Motor – Diesel Motor Accessories: Inspection And Mainten
Danfoss Motor : “How to check and maintain the three major accessories for diesel engines?”
First, the inspection and judgment of the technical status of the accessories
1. Inspection and judgment of the technical status of the plunger pair
(1) Observation method: Observe the traces of the most severely worn parts. If there is obvious sensation when using the nails to move horizontally, the new parts should be replaced.
(2)Experience method: clean the plunger pair with diesel oil, and make the sleeve full of diesel oil. Use your fingers to block the oil inlet hole, oil return hole and center hole of the plunger sleeve, and then pull out the plunger. Relax after the length of /3. If you can return immediately, you can continue to use it; otherwise, you should replace it with a new one.
(3) Pressure gauge inspection method: connect the pressure gauge to the pump head, place the throttle valve at the maximum fuel supply position, open the decompression and crank the vehicle, so that the plunger pair pumps the oil at a rate of 30 times per minute. The pressure must be greater than 19.6 kPa; otherwise, new parts should be replaced.
2. Inspection and judgment of the technical status of the oil outlet valve
(1) Observation method: Observe the seal ring belt. If the width of the seal ring is more than 0.5 mm, or the pressure relief belt has obvious wear groove marks, the original bright surface should not be seen, and new parts should be replaced.
(2) Pressure oil test method: remove the high pressure oil pipe of the cylinder to be inspected, open the inspection window of the fuel injection pump, shake the plunger of the cylinder to the bottom dead center, pump oil with the oil pump, first remove the air in the oil passage, then observe There is no leakage at the high pressure tubing joint. If there is leakage, replace it with a new one (this method cannot check the decompression ring).
(3) Pressure gauge inspection method: This inspection should be carried out simultaneously with checking the plunger pressure. When the pressure gauge pointer steady value is equal to 19.6 kPa and the time required to drop to 17.65 kPa after stopping the oil supply, if it is not less than 15 seconds, the sealing is good; immediately after the pressure is raised to 24.52 kPa, the oil is cut off immediately. Pay attention to the position of the needle back swing. If it is 0.98-6.87 kPa, the decompression effect is normal. Only when the seal is good can you see the exact value of the back swing.
When there is still a fault in the above inspection, the oil discharge valve should be removed, and the wear condition should be observed after cleaning. If there is no obvious groove mark, the high-pressure copper pad is not worn. Generally, after cleaning, the sealing surface is ground and properly tightened to restore the normal position; otherwise, it should be replaced with a new one.
3. Inspection and judgment of the technical status of the injector
This inspection should be carried out under the premise that the plunger pair and the outlet valve are working normally.
(1) On-board test method: When the rest of the motor is normal, the injector can be coarsely adjusted and then loaded onto the vehicle. When the motor is started, it is debugged in the car by “listening to the sound and watching the exhaust”.
(2) Standard nozzle comparison method: This method is to compare the normal injector adjusted in advance with the nozzle to be inspected. First connect them to the fuel injection pump with a three-way pipe, then discharge the air in the oil circuit and put the throttle in the maximum position. Open the decompression crank and observe whether the injection conditions of the two injectors are consistent. If the two injectors are injected at the same time, or the fuel injection is stopped at the same time, the atomization status is also the same, indicating that the injectors being inspected are qualified.
(3) Pressure gauge inspection method: Use a tee pipe to connect the pressure gauge and the inspected fuel injector in parallel with the fuel injection pump, and place the throttle valve at the maximum position. Turn on the decompression brake pump oil to express the pressure to 9.8 kPa (in combination with the adjustment pressure spring). Then, the fuel injection nozzle is sprayed at a speed of about 10 times per minute, and there is no oil drop at this time. After the above work is completed, the needle valve is adjusted to a predetermined pressure, and then the atomization test is performed at a speed of about 80 times per minute. The droplets should be fine and evenly distributed. The direction of the oil bundle and the cone angle should meet the requirements. The cutting of the oil bundle should be simple and have a special crisp sound.
When there is still a fault after the above inspection, the needle valve, the ejector pin and the spring should be removed for cleaning inspection. If it is really impossible to return to normal due to severe wear, replace it with a new one.
Second, measures to extend the service life of the even parts
In addition to product quality problems, the root cause of the damage of the even parts is mainly caused by improper use of the machine, maintenance and repair is not timely and incorrect. Let me talk about some measures taken to extend the service life of the coupler for reference.
1. Strictly implement the fuel precipitation filtration system. The fuel oil to be injected should be taken at least after 48 hours of precipitation. The diesel used should meet the standard model specified by the season. Refueling tools should be cleaned. The place for refueling and oil storage should also be cleaned to prevent the dirt from being mixed into the fuel to accelerate the wear of the parts and reduce the service life of the coupling parts.
2. Develop strict technical maintenance specifications. The fuel filter works for 100 hours, and the fuel tank works for 500 hours. If the filter core breakage effect is found to be replaced in time, it should not be removed and DC oil supply should be used. The parts should be disassembled and inspected once under normal working conditions for 500 hours. Keep the place, hands, tools and cleaning oil clean during disassembly inspection to avoid contamination of the parts. Do not tamper with the disassembly during the disassembly operation. Do not pile up indiscriminately during cleaning. Do not wash with other non-parts to avoid bumps and abrasions. Do not arbitrarily change the assembly position during assembly to achieve certain objectives that do not meet the machine’s working requirements. When installing the oil valve tight seat and the oil nozzle tight cap, it should be tightened according to the specified torque to ensure the technical state of the injector and fuel injection pump after assembly.
3. In addition to the above requirements, it is also necessary to improve the understanding of the pair of parts, understand the structural characteristics and working principle of the coupling parts, strengthen and improve the maintenance and operation of the pair of parts, and do not adjust it freely when there is no fault. Do not disassemble, do not mess with the repair and inspection, do not mess with the cleaning and maintenance, do not mess with the assembly adjustment, all in accordance with the technical requirements of the specification, in order to achieve the purpose of extending its service life.
https://www.xjetl.com
