Long needle valve for fuel injection valve

Abstract

The invention relates to a long needle valve for a fuel injection valve. The long needle valve is longitudinally and movably arranged in a central hole of a needle valve body, the head of the long needle valve is provided with a needle valve sealing conical surface, and the conical surface is matched with a needle valve body sealing conical surface in the needle valve body; the portion, located onthe needle valve body sealing conical surface, of the head of the needle valve body is provided with a plurality of injection holes; and the head of the long needle valve is provided with a guiding section and a throttling section which are in coupling fit with the central hole of the needle valve body, a plurality of throttling section flat positions are arranged on the circumference of the throttling section, the flat positions and the inner wall of the central hole of the needle valve body form a circulating cross section, and a specific value of the area S1 of the circulating cross section to the sum of the area of all the injection holes is t. According to the long needle valve for the fuel injection valve, it can be guaranteed that the long needle valve vertically maintains the reasonable pressure difference in the working process, chattering in the movement process is avoided, and the injection precision and the stability of an oil injector are improved; and in addition, the structure is simple, and the high economical property is achieved.

Description

technical field [0001] The invention relates to the technical field of engine fuel injection valves, in particular to a long needle valve used for fuel injection valves. Background technique [0002] 1. In the fuel injector assembly disclosed in CN103423049A, a typical structure of the fuel injector is given. In this assembly, the control piston and the nozzle needle valve are of split design, and the upper part of the needle valve is in contact with the lower part of the control piston. Placed in a low-pressure chamber, due to the existence of the low-pressure chamber, as the rail pressure rises, there will be a large amount of leakage in the gap between the coupling parts of the structure, resulting in a large amount of power loss of the oil pump, and due to the split structure, the fuel injector The response speed is relatively lagging. [0003] 2. In order to meet higher pressure requirements, currently, the design of fuel injectors tends to have a structure without sta...

AI Technical Summary

Problems solved by technology

However, this typical example does not effectively control the throttling size of the throttle valve. The throttling pressure drop generated by the throttle valve is very important for the stability of fuel injection. When the pressure drop is too low , especially under high rail pressure conditions, it is very easy to cause fuel injection instability, so that the engine cannot meet the requirements of regulations, and the actual processing of this structure requires high processing accuracy and high processing costs

[0004] The current mainstream fuel injection valve adopts the design structure of the control piston and the needle valve of the nozzle. This structure of the injector has a low-pressure chamber. During operation, the high-pressure oil leaks into the low-pressure chamber through the gap between the coupling parts, resulting in the energy loss of the high-pressure oil. loss, thus wasting the effective power of the oil pump and engine, and the split structure increases the number of moving parts, dragging down the response speed of the needle valve movement;

[0005] In the existing fuel injection valve with long needle valve structure, there is a throttle valve mechanism, and the throttle pressure drop generated by the throttle valve is very important for the stability of fuel injection. However, the stability of the fuel flow has not been clearly stated. When the pressure drop is too low, especially in the case of high rail pressure, it is very easy to cause fuel injection instability, so that the engine cannot meet the requirements. The requirements of laws and regulations, and in the actual processing of the existing technology, the processing accuracy is very high, and the processing cost is high

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