common rail tester

How to choose a common rail tester?

How to choose a common rail tester?
There are many manufacturers of common rail tester 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.

The main factors affecting the test accuracy of the common rail test bench include hardware and software:
Hardware: common rail, fuel pump, fuel temperature control system
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.
This is the key hardware needs attention. In the next chapter, we will introduce the software and other content.

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 key factors, 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. I will continue to talk later, hoping to help customers choose the common rail test bench that they are satisfied with.

fuel injection pump working principle

Fuel injection pump working principle-2

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

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?

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.