common rail fuel injector tester

What Is A Seventh Common Rail Injector?

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What is seventh common rail injector?
Since 2017, Main big cities in China such as Beijing, Zhengzhou, Shenzhen, Shandong, Hangzhou and other places have successively issued notices of the stopping Euro 3 vehicles , many car owners have gradually realized that the days of eliminate the Euro 3 vehicle are getting closer.

Shenzhen announced that since November 1st, Shenzhen began to implement the Euro 6 emission standards for light-duty vehicles and light-duty diesel vehicles. The news that the stricter Euro 6 emission regulations will be reached is being rumored, and major manufacturers are also actively responding, and successively launched their own Euro-6 engine products, and its products in China have appeared as the “seventh injector” components, then what is the seventh injector?

First of all, let us first look at the Volvo D13K Euro 6 engine is actually with the seventh common rail injector, many people may find this injector is at the post-processing end, named as the seventh injector is a bit far-fetched, but this The naming rules are still very common in foreign countries. For example, the “fifth round” that we often hear in the materials actually refers to the traction saddle of the vehicle.

The “seventh injector” mainly appears on the engine after the DPF is used to process the fuel-assisted combustion regeneration technology. As the name suggests, the engine system has an additional common rail injector.

Of course, it is not uncommon to have an extra injector on the engine. Some gasoline engines in the early years were equipped with a cold start auxiliary injector on the intake pipe, while the “seventh injector” of the diesel engine was It is installed on the exhaust side of the engine to meet the PDF regeneration function.

Because of the emissions from the Euro-6, post-processing generally uses a particle trap (DPF), which means that DPF regeneration will be involved. During the working process of DPF, as the trapping particles gradually increase and block the muffler, the exhaust back pressure of the vehicle increases accordingly, and the accumulation of particles to a certain extent will affect the power and economy of the engine.

The process of the vehicle DPF autonomously removing particles is called the regeneration process. Of course, there are many ways to regenerate, and the active regeneration of the DPF (mainly fuel-assisted combustion regeneration) requires the participation of the “seventh injector”.

Because the fuel-assisted combustion regeneration technology is not limited by the quality of the fuel, the burner uses the same fuel as the diesel engine, and the components are mature. There is no need to make major changes to the original structure of the engine when loading the vehicle. All of them will choose such a technical route. For example, the Euro 6 Volvo engine, the domestic Weichai and the heavy duty HSC products all use fuel injection combustion regeneration technology.

Of course, many manufacturers do not install the “seventh injector”. For example, Futian Cummins’s National Sixth Engine gave up the EGR system, and its DPF regeneration technology does not have the aforementioned seventh injector. Its DPF post-treatment does not use fuel injection combustion regeneration technology.

The Cummins engine’s after-treatment uses a U-shaped structural arrangement, which is DOC, DPF, ammonia decomposition and mixing, SCR and ammonia escape monitoring from the exhaust end of the engine, compared with the models of the ordinary four-nation five SCR technology route, except for the structure. More complicated, the most obvious change above is the super-multiple sensors, in which there are five temperature sensors, two NOx sensors added to the two, and a differential pressure sensor consisting of front and rear pressure sensors that detect DPF status.

Of course, upgrading the Euro-6 is not only for the choice of EGR, but also for the DPF and SCR who should be on the upstream side of the differences, the performance of different manufacturers is also different.

When the DPF is upstream of the SCR, the advantage is that the regeneration of the DPF is easy to achieve and the fuel consumption is low; and when the SCR is upstream of the DPF, the main advantage is that the ignition-off characteristics of the SCR are good.

In fact, upgrading from the Euro-5 to the euro-6 is not as simple as the imagination. From the Euro-5 to the 6, it is necessary to overcome the triple challenge of sensors, fault codes and control parameters.
The number of sensors has increased from more than 30 to more than 60;
The number of fault codes has increased from more than 150 to more than 430;
The control parameters have increased from 10,000 to more than 15,000.

On the basis of the Euro 6 onboard diagnostic system, Guoliu also refers to the permanent fault code anti-cheat requirement proposed by the US OBD regulations, and applies the requirements of the remote emission management vehicle terminal (remote OBD) to the national standard for the first time, which also means The national six emissions will face more complete and strict national monitoring.

common rail tester

How To Choose A Common Rail Tester?

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How to choose a common rail tester?
There are dozes of  common rail tester manufacturers on Chinese market. Each of them promotes the quality of their common rail tester. The price of the common rail tester ranges from tens of thousands to hundreds of thousands.
Today, I will briefly explain here how to choose a suitable common rail test bench,below are some important facts for your reference, hope it will be helpful for you.

1.The weight of the common rail tester, the weight of determines its own balance and shake. Usually, the test bench with relatively low price can be obviously felt that it is shaking during the test, and the balance of the common rail tester bench is not good.

2.The power of the common rail tester, some customers need 7.5KW, some customers want 18.5KW, the standard power produced by the test bench manufacturers in China is 11KW and 15KW, the power is different, the components equipped on the test bench is different, such as  universal joints ,coupling, frisbee, and the weight of these parts determines the smoothness and inertia of the speed.

3.The quality of the main parts which are on the common rail tester: fuel pump, rail, DRV, pressure sensor, control valves, must ensure that are geniune and new, such as bosch DENSO DELPHI pumps and rails are good choice, regarding these parts, i would like to say a little more, after all, it is too important for a common rail tester’s performance.
The common rail is the pressure accumulator, and the fuel pump is the source of power.
The stability of pressure and fuel temperature will directly affect the repeatability and stability of the test data.
That is to say, the performance of the rail and the common rail pump will directly affect the accuracy of the data.
But in order to confuse customers, some manufacturers will work hard on the software to keep the pressure data displayed on the test bench in a stable state, to cheat customers. At this time, you can take a mechanical pressure gauge to test whether the actual pressure and the displayed pressure on the test bench are consistent.
Or you can take a single test on the test bench with a fuel injector, single-step test and continuous test to check the repeatability and stability of the data.
Regarding the rail of the common rail tester, some manufacturers use the original Bosch rail, means rail and DRV are together( complete), but more manufacturers in order to save costs, fight with others by cutting prices , they use the common rail from Chinese market, some are dismounted from engine, and clean the appearance, and DRV (DRV also has different places to produce ), with an adaptor in the middle (I personally refer to call this  as “rail combination”), such a combination of rails will be much cheaper than the original rail, but according to the test experience of the test bench manufacturers, this The rail combination can also be used to meet the test requirements. After all, most of the customers need to buy a cheaper common rail tester, but I am not a professional technician. I don’t know how much is the difference of the influence in the performance of the test bench by using the this two types rails on the common rail test bench,
Regarding the fuel pump, the pump of CP3 is generally equipped on the common rail test bench, and the pump of the CP1 is equipped on the fuel injector tester, but the new original pump on the test bench which are bought by foreign customers , because for foreign customers, it is not easy to do the after-sales service,  in order to avoid future problems, usually use new genuine fuel pump, for China domestic customers, they prefer the cheap common rail test bench, and easy for after-sales service, so it is usually equipped with second-hand pump, that is, removed from the engine, but the performance is still intact.
In addition to these important components, the quality of other hardware on the common rail tester needs to be noted. For example, inverters, the good brand is such as LG or Siemens. Lower level is that made in Taiwan or China mainland, the cost is a little cheaper, like therail combination I talked about above, it can meet the test basic needs, but who know after 5-10 years?
There are other factors.

4.The flow sensor is the main core component of the common rail tester. The pulse is hundreds to more than ten thousands. The larger the pulse, the more accurate the precision and the quality, the price will vary greatly (without the sensor, the test bench is a scrap iron, one customer said). that the accuracy of the sensor directly determines the accuracy of the tested fuel. Some common rail test bench manufacturers use high-precision gear flow meters produced in Germany. Some manufacturers use Australian flow sensors. Some manufacturers use OEM China flow sensor. The flow sensor is produced in China, but the it shows the original name. In general, the German flow meter is the most expensive and the best quality.

5.Fuel circuit layout and fuel temperature control system are also very important. The test bench producer in China mainly use two types temperature controlling system, air-conditioning refrigeration and air-cooling. The air-cooled system is relatively simple, and there is no problem of after-sales service. However, the temperature control of air conditioning and refrigeration can  control the temperature more well

6.The selection of electronic original devices also affects the service life of the common rail test bench. These small components can only be seen by the customer to see its quality. If the quality of the electronic components are not good, the test bench will have some minor problems, although they are not big, but they will make you feel bad.

7.The software control system of the common rail test bench. After more than 10 years of development, there are only 2-3 software producer in China to supply circuit board to all these test bench manufacturers, that is, it is possible that many test bench manufacturers use the same software system, just These programmers have designed different appearances for different test bnech manufacturers, avoiding the embarrassment that customers have identified as “plagiarism.” These programs are slightly different, each with its own advantages, customers can choose the style they like. If there is a problem with the test bed software, the after-sales solution is usually to replace the board directly.

8.Finally, user-friendly design and a better user experience of the common rail tester are also important.

9. Hoping my above ideas can be helpful for you to choose the common rail test bench that you are satisfied with.

fuel injection pump working principle

Fuel Injection Pump Working Principle-2

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3.Fuel injection pump working principle – – structure

The fuel injection pump is mainly composed of a pumping mechanism, a fuel supply amount adjustment mechanism, a drive mechanism, and a fuel injection pump body. Wherein, the pumping mechanism comprises a plunger coupler, an oil outlet valve coupler, etc.; the oil supply amount adjusting mechanism refers to a rack type oil quantity adjusting mechanism or a fork type oil quantity adjusting mechanism; the driving mechanism comprises a cam shaft, a tappet assembly, etc. The fuel injection pump body is the mounting base of the above three, which requires sufficient strength, rigidity and sealing, and is easy to disassemble, adjust and repair.

4. Fuel injection pump working principle

fuel injection pump working principle

Suction process: the plunger is driven by the cam of the camshaft. When the convex part of the cam leaves the plunger, the plunger moves down under the action of the plunger spring, the volume of the oil chamber increases, and the pressure decreases; when the plunger is sleeved When the radial oil inlet hole is exposed, the fuel in the low pressure oil chamber flows into the pump chamber along the oil inlet hole.

Pumping process: When the convex part of the cam pushes up the plunger, the volume in the pump chamber decreases, the pressure increases, and the fuel flows back to the low pressure oil chamber along the radial oil hole on the plunger sleeve; When the upward flow to the radial oil hole on the plunger sleeve is completely blocked, the pressure on the pump chamber increases rapidly; when the pressure overcomes the preload force of the fuel valve spring, the oil discharge valve moves up; when the oil discharge valve is on When the pressure relief belt leaves the valve seat, the high pressure diesel fuel is pumped into the high pressure oil pipe and injected into the cylinder through the injector.

Fuel return process: As the plunger continues to move upward, when the chute on the plunger communicates with the radial oil hole on the plunger sleeve, the fuel in the pump chamber passes through the axial oil passage on the plunger, obliquely The oil hole on the oil passage and the plunger sleeve flows back to the low pressure oil chamber, and the pumping stops.

fuel injection pump working principle

Fuel Injection Pump Working Principle-1

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1.Fuel injection pump working principle-introduction

The fuel injection pump is an important part of the diesel engine. The crankshaft gear of the engine drives the camshaft to rotate to complete the fuel injection function. The fuel pump is usually equipped with a governor to ensure the low speed operation of the diesel engine and the limit of the maximum speed, and to ensure a certain relationship between the injection quantity and the rotation speed.

fuel injection pump working principle..

2. fuel injection pump working principle – – classification
The fuel injection pump can be mainly divided into three types: a plunger type fuel injection pump, a fuel injection pump-injector and a rotor distributed injection pump. Among them, the plunger type fuel injection pump is the oldest and most widely used, with high reliability; the unit pump combines the two into one, directly mounted on the cylinder head of the engine, and can eliminate the high pressure fuel pipe. The adverse effects (requires additional drive mechanism on the engine); the rotor-distributed fuel injection pump has only one pair of plungers, mainly relying on the rotation of the rotor to achieve fuel pressurization and distribution, with small size, light weight and convenient use. Low cost and other characteristics.

In China, the fuel injection pump is based on the plunger stroke, the center distance of the pump cylinder and the structure type, and is respectively equipped with plungers of different sizes to form several kinds of fuel injection pumps with different fuel supply amounts in one working cycle to form I. II, III and A, B, P, Z series to meet the needs of various diesel engines.

Common Rail Tester Engine Test Stand Injector Pump Calibration

How The Common Rail Works In The Engine?

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Electronically controlled fuel injection technology directly or indirectly forms a constant high-pressure fuel through a common rail, distributed to each injector, and opened and closed by means of a high-speed electromagnetic on-off valve integrated on each injector, timing, The amount of fuel injected into the combustion chamber of the diesel engine is controlled in a very large amount to ensure that the diesel engine achieves an optimum combustion ratio and good optimization, as well as optimum ignition time, sufficient ignition energy and minimum pollution emissions. Now the new technology has begun to be put into use in cars powered by diesel engines abroad. This is an inevitable trend for the world’s automotive industry to meet increasingly stringent emission standards.

Electronically controlled common rail: “Electric control” means that the fuel injection system is controlled by a computer. The ECU (commonly known as the computer) precisely controls the injection quantity and injection timing of each injector, which can make the diesel engine fuel economy and power. The best balance is achieved, while the traditional diesel engine is mechanically controlled and the control accuracy cannot be guaranteed. “High pressure” means that the pressure of the fuel injection system is 1.1 times higher than that of the conventional diesel engine, and the maximum energy can reach 145 MPa (while the traditional diesel engine injection pressure is 60-70 MPa). The pressure is large and the optimization is good enough to burn, thus improving the power. Sexuality, ultimately achieving the goal of fuel economy.

The “common rail” is to supply the fuel injectors through the common fuel supply pipe. The fuel injection quantity is accurately calculated by the ECU, and the fuel of the same quality and the same pressure is supplied to each fuel injector to make the engine run more smoothly, thereby optimizing the diesel engine. Comprehensive performance. The traditional diesel engine is injected by each cylinder, the injection quantity and pressure are inconsistent, and the operation is uneven, resulting in unstable combustion, high noise and high fuel consumption.

 

In order to detect the common rail system, the high-pressure common rail tester is finished, it is a special test bench designed for test high-pressure common rail injector and pump calibration, and can complete various functional tests of high-pressure common rail systems.