The design criterion for fuel supply is to ensure the sum of the diesel engine's injection volume and control oil volume under any circumstances, as well as the need for oil quality changes during start-up and acceleration. Since the generation of injection pressure in common rail systems is independent of the fuel injection process, and the injection timing is not guaranteed by the cam of the high-pressure oil pump, the pressure oil cam of the high-pressure oil pump can be designed according to the design criteria of minimum peak torque, minimum contact stress, and maximum wear resistance. Bosch uses a three-cylinder radial piston pump driven by a diesel engine to generate pressures up to 135Mpa. In each oiling unit of this high-pressure oil pump, multiple oiling cams are used, reducing its peak torque to 1/9 of that of traditional high-pressure oil pumps, making the load more even and reducing operating noise. In this system, the pressure in the high-pressure common rail cavity is controlled by discharging fuel from the common rail cavity. To reduce power consumption, when the injection volume is small, one oiling unit of the three-cylinder radial piston pump will be closed to reduce the fuel supply. Nippon Denso uses an inline pump with a three-action cam to produce high pressure. This high-pressure oil pump controls the oil volume by controlling the effective intake volume of low-pressure fuel.
a) The plunger moves down, the control valve opens, and low-pressure fuel flows into the plunger chamber through the control valve;
b) The plunger moves up, but the control valve has not been powered and remains open, allowing low-pressure fuel to flow back into the low-pressure chamber through the control valve;
c) When the fuel supply timing is reached, the control valve is powered, closing it and cutting off the return oil circuit. The fuel in the plunger chamber is compressed, and the fuel passes through the outlet valve into the high-pressure oil rail. By varying the closing time of the control valve, the amount of fuel entering the high-pressure oil rail is controlled, thus achieving the purpose of controlling the pressure in the high-pressure oil rail;
d) After the cam has passed its maximum lift, the plunger enters the downward stroke, the pressure in the plunger chamber decreases, the outlet valve closes, and fuel supply stops. At this point, the control valve stops being powered and remains open, allowing low-pressure fuel to enter the plunger chamber for the next cycle.
This method prevents the high-pressure oil pump from generating unnecessary power consumption, but requires determining the width of the control pulse and the phase relationship between the control pulse and the cam of the high-pressure oil pump, resulting in a relatively complex control system.
The common rail distributes the high-pressure fuel supplied by the fuel pump to each injector and acts as an accumulator. As shown in Figure 4, the ECD-U2 system's common rail should reduce the fluctuations in the fuel supply pressure of the high-pressure oil pump and the pressure vibrations caused by the injection process of each injector, keeping the pressure fluctuations in the high-pressure oil rail below 5Mpa. However, its volume cannot be too large to ensure that the common rail has sufficient pressure response speed to quickly track changes in the diesel engine's operating conditions. The maximum circulation fuel supply volume of the high-pressure pump in the ECD-U2 system is 600mm3, and the common rail volume is 94000mm3.
The high-pressure common rail also mounts a pressure sensor, fluid buffer (limiter), and pressure limiter. The pressure sensor provides the ECU with the pressure signal in the high-pressure oil rail; the fluid buffer (limiter) ensures that fuel supply to the injector is cut off in case of a fuel leakage fault in the injector, and reduces pressure fluctuations in the common rail and high-pressure oil pipe; the pressure limiter ensures that the pressure in the high-pressure oil rail is discharged quickly in case of abnormal pressure.
From the above analysis, it is not easy to correctly plan the volume and shape of the high-pressure common rail suitable for a specific diesel engine. For difficulties starting the car in cold weather, experts have proposed several suggestions.
Tools/Materials: Car
Steps/Methods:
If the battery is out of power,
"A depleted battery is one of the main reasons for difficulty in starting the car." Since the battery is a frequently used device, there may be consumption and discharge, leading to insufficient charging. And having a charged battery is one of the main sources of power for starting the car. Once depleted, the car will definitely fail to start normally. Therefore, first check the battery, then check the generator and belt for any faults such as looseness. The battery requires regular maintenance, generally observed through the round inspection port on top to see if it needs replacement. Normally, it appears blue-green, but if it lacks power or is abnormal, it will show white or yellow.
If the car has traveled a long distance, carbon deposits will form in the combustion chamber, and these carbon deposits could be one of the main culprits for difficulty in starting the car. Because carbon deposits have a certain adsorption effect, they will absorb part of the fuel sprayed into the combustion chamber, thereby causing the spray volume to be too low, resulting in too low a concentration of the air-fuel mixture. Once the concentration of the air-fuel mixture is too low, it cannot be ignited normally, making it difficult to start the car. The fuel adsorbed on the surface of the carbon deposits will volatilize again when exposed to high temperatures, so if you start the car several times, it can eventually start smoothly, but it takes longer.
In such cases, the best solution is to add a fuel additive, allowing the additive to gradually clean the carbon deposits in the engine. If you want to clean it quickly in one go, you can also go to the 4S store for a non-disassembly or disassembly cleaning of the engine. Attention should also be paid to changing the engine oil.
Some car owners might say, my car is new, there won't be carbon deposits, and the battery is normal, but why is there still difficulty in starting? Then it might be that your engine oil hasn't been changed. Engine oil comes in many types; some can be used universally and can be used normally in summer and autumn, but others are graded. Oil that can be used in summer may not function properly in the cold winter.
Precautions:
If your engine oil is unsuitable for winter use, it will become very viscous and cannot perform normal lubrication, and may even cause blockages, so it must be replaced in a timely manner.
Reference materials: What to do if your car is hard to start in winter: The above content is jointly published by the Sanitation Garbage Truck Official Website (http://www.clwlu.com/)|www_clwlu_com and Garbage Truck Professional Manufacturer (http://www.clwwcw.com/)|www_clwwcw_com. For more exciting content: Water Sprinkler Truck Prices originally intended to check and tighten using ordinary tools. Oil Tanker Model Numbers