Designing a post with the development of a common rail repair card on a WV Passat B5 Diesel car

Introduction

The diesel engine power supply system is designed to provide fuel reserve on the car, clean the fuel and distribute it evenly among the engine cylinders in strictly metered portions in accordance with the operating order, speed and load mode of the engine.

The working process of diesel engines differs from carburetor ones:

If the cylinders of carburetor engines receive a combustible mixture consisting of fuel vapors with air, then only air is supplied to the cylinders of diesel engines, which at a high compression ratio acquires a temperature higher than the self-ignition temperature of the fuel; fuel is injected into cylinders under high pressure and is self-ignited without spark supply .

For diesel engines, diesel fuel is used as combustible fuel, which includes heavier oil fractions than gasoline.

Diesel fuel shall have the following properties:

• provide soft and smooth operation of the engine;

• have a certain viscosity;

• solidification temperature;

• contain no mechanical impurities.

To ensure soft operation of the diesel engine, it is necessary that during fuel combustion the pressure in the cylinders gradually increases. Therefore, the fuel must self-ignite immediately after the first particles of the fuel enter the cylinder and burn uniformly as the fuel is injected. When ignition is delayed, a significant amount of fuel accumulates in the cylinder, the simultaneous combustion of a large amount of fuel leads to a sharp increase in pressure and hard operation of the engine.

The ability of diesel fuel to rapidly self-ignite is determined by the cetane number. This number corresponds to the percentage of cetane in the mixture with alphamethylene naphthalene, provided that the mixture is equivalent in flammability to the diesel fuel tested. The freezing temperature of diesel fuel shall be 1015 ° C lower than the ambient temperature. Fuel is considered frozen if it is poured into a tube, loses mobility within 1 minute when the tube is inclined at an angle of 45 °. Temperature of fuel freezing depends on its friction composition. The heavier fuel has a high pour point.

Diesel fuel viscosity shall be strictly defined. With high viscosity, it is difficult to supply fuel and spray it. Low viscosity does not provide sufficient lubrication of fuel pump parts and nozzles.

The fuel equipment of diesel engines is made with a high accuracy class, therefore, water and mechanical impurities are not allowed to enter the fuel. And this principle of the operation of the power system was laid down in 1890 by the German engineer and inventor Rudolf Diesel, who developed the theory of an "economical thermal engine," which, due to the strong compression in the cylinders, significantly improves its efficiency. Since that time, diesel engines have firmly entered the design of cars .

Currently, the development of German automotive engineering is gaining momentum. In this regard, the volume of repair work is also increasing.

Car repair allows you to extend their service life, which ensures an increase in the fleet of road transport rolling stock.

The improvement of repair production efficiency can be achieved as a result of the improvement of all stages of the production process of car repair, the use of new, especially energy-saving, technologies for the wide use of composite, synthetic, polymer and other promising materials.

Rectification of faults during the current repair of the car in auto farms is carried out by simple repair operations related to partial or complete disassembly of the car units and assemblies or replacement of units requiring overhaul.

The current repair of the unit or assembly consists in the replacement or repair of worn or damaged parts, except for basic ones.

Car repair is carried out by one of two methods:

aggregate;

individual.

With an individual repair method, faulty units are removed from the car, repaired and installed again on the same car. With this repair method, the units are not impersonated, and the downtime of the car is determined by the duration of repair of the most labor-intensive unit.

With the individual method, there is a significant duration of car downtime in repair, as a result of which this method is used only in extreme cases when there is no stock of replacement units in the car farm.

The aggregate method of repairing cars consists in replacing faulty units with serviceable ones, previously repaired or new ones from the revolving fund. The unit (unit) is replaced in the case when it takes more time to repair faults directly on the car than to replace it, and when repairs cannot be carried out at interchange time. The faulty unit removed from the car is repaired, after which it goes to the revolving fund.

The main advantage of the aggregate method is the reduction of the car downtime in repair, which is determined only by the time required to replace one or more faulty units or assemblies. The reduction in repair downtime leads to an increase in the technical readiness factor of the fleet, and therefore an increase in its productivity and a decrease in the cost of transportation. Therefore, the provision on maintenance and repair of rolling stock of road transport provides, as a rule, an aggregate method of car repair.

Faulty units, units and devices removed from the car are transferred (through an intermediate warehouse) to the corresponding production areas, where they are exchanged for serviceable ones. The site manager determines the nature and scope of repairs.

The units are handed over for overhaul in accordance with the current specifications for cars and units being handed over for repair. Units are accepted from overhaul after their testing on stands in accordance with specifications for cars and units accepted from repair. The topic of this diploma project is considered using the example of cars of the German manufacturer WV.

Relevance of the topic: due to the fact that the diesel equipment repair site is an integral part of the automobile enterprise. And the level of qualification and the requirement for the quality of the work performed increases, it is necessary to investigate methods of repairing Common Rail diesel equipment. Consider modern equipment for repair.

The main task of the diploma project is: the development of a site for the repair of the diesel engine power system with the selection of the necessary equipment and tools.

The purpose of the diploma project is: Designing a post with the development of a repair map for the Common Rail system on a WV Passat B5 Diesel car

Purpose of LPT

The HPVs are designed to supply to the cylinders at a certain pressure and at a certain point in the cycle, accurately measured portions of fuel corresponding to this load applied to the crankshaft. According to the injection method, direct fuel pumps with battery injection are distinguished.

Direct action fuel pump carries out mechanical drive of plunger, and pumping and injection processes take place simultaneously. Fuel pump section supplies required portion of fuel to each cylinder. The required spray pressure is generated by the movement of the pump plunger.

Fuel pump with accumulator injection is driven by working plunger due to pressure forces of compressed gases in engine cylinder or by means of special springs. On powerful slow-moving diesel engines, accumulator fuel pumps with hydraulic accumulators are used.

In systems with hydraulic accumulators, injection and injection processes are separate. Previously, high pressure fuel is pumped into accumulator from which it is supplied to nozzles. This system provides high-quality spraying and mixing in a wide range of diesel loads, but due to the complexity of the designs, such a pump has not been widely used. Modern diesel engines use technology with the control of electromagnetic valves of nozzles from a microprocessor device (this combination is called "common rail").

Principle of TNVD operation

Pump consists of housing, cam shaft and six pump sections. An automatic clutch is attached to the pump front, and the housing of the all-mode crankshaft RPM controller is attached to the pump housing at the rear.

Pump supplies fuel to nozzles by its sections. Main parts of pump section are sleeve and plunger. Both parts are selected individually in pairs with a gap of 0.001 mm, and they are interchangeable.

Plunger receives push from camshaft cam through roller pusher. Pusher has return spring and adjusting bolt with lock nut. Pusher spring with its second end rests against plate. The sleeve has side holes through which it is filled with fuel from the channel. Pressure valve with spring and stop is installed above plunger. The section is closed from above with a swivel nut with a high-pressure discharge pipeline. The sleeve is fixed in the housing by a locking screw, and the plunger is connected to the regulator rack through a rotary bushing and a toothed sector; The latter turns the plunger relative to the holes. Plunger has vertical channel connected with through horizontal channel.

Plunger is lowered under action of pusher spring. A vacuum is created above the plunger, fuel through open side holes in the sleeve fills the space above the plunger.

When the cam runs into the pusher, the plunger rises. When the plunger closes the hole in the sleeve, the pressure increases above it, the pressure valve rises, and fuel begins to be supplied to the nozzle. The fuel supply continues until the spiral recess opens the opening in the sleeve. When this occurs, the upper plunger space through the vertical channel in the plunger and the hole in the sleeve will communicate with the fuel supply channel and fuel bypass to this channel will begin. The fuel supply stops, although the plunger still continues to move upward. The amount of fuel supplied is adjusted by turning the plunger. Plunger is turned by means of rack, toothed rim and rotary bushing.

The pressure valve serves to disconnect the above-plunger space and the high-pressure fuel line after the fuel supply is completed, preventing the fuel from flowing back from the pipelines to the above-plunger space of the pump and unloading the pipeline from the high residual pressure.

The valve has a discharge belt which fits precisely to the surface of the valve seat. When the lower edge of the belt reaches the guiding surface of the seat, the fuel line is separated from the upper plunger space of the sleeve. When the valve is further lowered until it is fully seated in the seat, the unloading belt releases a small volume above the belt. As a result, the fuel expands by the amount of free volume and the pressure inside the pipeline drops. Due to this, the injection is abruptly terminated and the fuel leaks from the injector to the cylinder are reduced.

Pitot-static tube failures

TNVD is an expensive and rather "whimsical" diesel engine unit, extremely demanding on the quality of fuel and lubricants. The main reason for the failure of the TNVD is the contamination of the pump plungers, which are installed in bushings with minimum tolerances measured in microns. Contamination of the plunger pair with solid particles contained in poor-quality diesel fuel can lead to the failure of the HPLC. No less dangerous is the water that can be contained in the fuel. Moisture erodes the protective oil film of the parts of the unit, which is fraught with jamming of the parts of the LPT. Also, a malfunction of the HPV may consist in the physical wear of the parts and damage to the pump housing.

Malfunction of the HPV usually leads to uneven supply of fuel to the nozzles of the engine and to a decrease in its incoming volume. To understand that the TNVD does not work normally, it is not necessary to wait for its breakdown. The following are signs of problems with LPT and with the fuel system as a whole:

increased fuel consumption;

unstable engine operation at low speed;

difficulties in starting the engine;

engine overheating;

fuel leakage;

drop in power and recoil of the diesel engine;

increased exhaust smoke;

appearance of foreign noises during engine operation.

Check of LPT

Ideally, the diagnosis of the HPV and troubleshooting can only be carried out on the bench - a device that allows to simulate the operation of the HPV in the operating ranges. However, since the cost of the stand is comparable to the price of the car, and for diagnostics it is necessary to dismantle the TNVD from the car, such operations are carried out only in car services. In "combat" conditions, it is quite difficult to check the TNVD, but still possible. However, you need to understand that at home it will be possible to diagnose only some TNVD malfunctions, and only a check on the stand will give a complete picture.

You can check the plunger pairs for water in them by removing the LPG belt and carefully twisting the pulley. If the pulley turns with variable force (due to rotation of the cam shaft), then there is no water in the bushings of the HPV. If the pulley does not turn, then there is water in the HPV system, which will cause jamming at engine start.

The pressure in the plunger pair can be checked using the tester TAD01A, KI-4802 or any other similar tool. Such a device can be manufactured even on its own, this will require a powerful pressure gauge. The tester is screwed into the LPT in place of the fuel tube or into the central hole of the pump head. The measurement shall be at least 300 kg/cm2. In the opposite case, the plunger pair is worn out and needs to be replaced or restored.

In diesel cars with electronic control of the HPV, the breakdown may consist in breaking the RPM sensor located on the pump body. In this case, the fuel does not come from the TNVD to the engine cylinder nozzles. To check the sensor, measure the resistance on the sensor connector located on the HPV cover using a multimeter. In the absence of resistance, a break occurred.

If the pitot-static tube malfunction is a fuel leak, the sealing rings of the unit are usually to blame. To check the pitot-static tube for leakage, pump the axis of the pitot-static tube lever at operating engine. If there is a fuel leak, the rubber seal should be replaced at the leak point. If leaks occur not on the axis, but in other places of the unit, for example, in places where plunger pairs fit, then for diagnostics it will be necessary to disassemble the TNVD.

Purpose of stand 04 K

Test bench 04K is designed for testing of high pressure diesel fuel pumps (HPVP) by reproduction of drive shaft rotation speed, fuel temperature and pressure, measurement of specified parameters, as well as cycle supply, fuel flow rate supplied to the test object, injection start angles, turn of injection advance clutch, deviation of injection start angles.

Stand 04 K is used for maintenance and repair of diesel fuel pumps.

Conclusion

In the diploma project on the topic: "Designing a post with the development of a repair map for the Common Rail system on a WV Passat B5 Diesel car." During the diploma project, a repair site with selected profile equipment was designed, and the main indicators and funds were calculated.

During the project implementation, the objectives and objectives of the project were considered:

The main task of the diploma project is: the development of a site for the repair of the diesel engine power system with the selection of the necessary equipment and tools.

The purpose of the diploma project is: Designing a post with the development of a repair map for the Common Rail system on a WV Passat B5 Diesel car

For uninterrupted operation of the diesel engine power supply system, its maintenance and repair should be carried out in a timely manner. The quality of these works depends directly on the qualifications of specialists and the state of the equipment.

The use of modern equipment for the maintenance and repair of cars facilitates and accelerates many production processes, but requires service personnel to learn a certain range of knowledge and skills: the construction of the car, the main technological processes of maintenance and repair, the ability to use modern instrumentation, tools and devices, as well as constantly improve their skills.

Well-organized maintenance, timely elimination of malfunctions in units and systems of the car, with highly qualified performance of work, allow to increase the durability of cars, reduce their downtime, increase the duration of inter-repair runs, which ultimately significantly reduces unproductive costs and increases the profitability of motor vehicles.

In the first section, the technical justification of the project is given: the norms of overhaul mileage, average values ​ ​ of overhaul mileage, labor intensity for conducting TO1, TO-2 and current repairs, car downtime during maintenance and maintenance, annual mileage and number of maintenance per year are calculated. The annual mileage of all cars for the year was km. 2710800. The second section defines the minimum number of workers in the department. The area of ​ ​ the compartment is 88m2. The labor intensity of the work at the post, taking into account the correction per 1000 km, was 2.8 people/h. One specialist is required to complete this scope of work. The average monthly salary in the region, which amounted to 79050 rubles, is also calculated. Expenses for the year 6038929.2rub were calculated. Equipment for the site was selected and detailed description was given. He also considered measures for health, safety and fire safety during electrical work .

In the economic part of the diploma project, the costs of materials and components, salary costs, expenses and the cost of repair work were calculated. The cost of repair work for 1000 km of mileage is 2228rub.

Thus, I believe that the goals and objectives of graduate design have been fulfilled.