Plane opening and closing structure of high-pressure common rail oil injector of diesel engine

Abstract

The invention discloses a plane opening and closing structure of a high-pressure common rail oil injector of a diesel engine. The plane opening and closing structure comprises a control valve coupler and a guide valve seat; the sealing ball in the control valve coupler is a planar sealing ball; an annular sealing plane, a throttling pit, a plane seal of a throttling hole and a quick pressure relief structure are arranged on the upper end face of the guide valve seat; the diameter of the sealing plane of the planar sealing ball is equivalent to the outside diameter of the annular sealing plane; and the hardness, the flatness and the surface roughness of the sealing plane and the annular sealing plane meet the design requirements. The sealing steel ball in the control valve coupler is changed into the planar sealing ball with the sealing plane, a sealing taper hole in the upper end face of the guide valve seat is changed into the plane seal, and the quick pressure relief structure is increased, so the sealing performance of high-frequency opening and closing is reliable, the machining manufacturability of a sealing element is greatly improved, the structure can be finished by adopting conventional metal machining and thermal treatment, the machining efficiency is high, the sealing performance and the quick pressure relief performance are stable and reliable, and the structure isan improvement on the conventional product of Robert Bosch GmbH of Germany.

Description

Technical field: [0001] The invention relates to a high-pressure common-rail fuel injector for a diesel engine, in particular to an opening and closing structure in the high-pressure common-rail fuel injector. Background technique: [0002] At present, there are three major companies in the world producing high-pressure common rail systems for diesel engines, Japan's Denso, Germany's Bosch and America's Delphi. The common rail system separates fuel pressure generation and fuel injection, and the common rail system opens up a new way to reduce diesel engine emissions and noise. In the context of the increasingly severe energy crisis, diesel engines have become the focus of attention of the internal combustion engine industry around the world, and diesel engines are increasingly favored by users. Compared with gasoline engines, diesel engines have many advantages: they can reduce CO by 20% to 25%. 2 Exhaust emissions, acceleration performance at low speeds are more advantage...

AI Technical Summary

Problems solved by technology

[0006] from figure 1 It can be seen from the sealing structure between the control valve coupler 6 and the valve assembly 7 and the sealing principle of the two, the control valve coupler 6 and the valve assembly 7 are achieved through the line contact between the sealing steel ball 64 and the throttling cone hole 73. For sealing, the diameter of the sealing steel ball 64 is 1.33mm to 1.34mm, and the diameter of the line seal formed by the contact between the throttling cone hole 73 and the sealing steel ball 64 is 0.68mm. In order to ensure that the valve cone surface has a good The machining accuracy must be ground by the world's top high-speed grinding machine, and its grinding speed is 120,000r / min. Even so, it is difficult for the throttling taper to meet the design requirements. The diameter is only 0.68mm. Although the speed of the grinding head is extremely high, the grinding line speed here is only 4.3m / s, which cannot meet the requirements of high-precision grinding, and the distance between the processed cone surface and the grinding head The friction force is very high, and the high temperature of grinding is easy to anneal the cone surface, resulting in a decrease in hardness, and the machining accuracy of the throttling cone hole is difficult to meet the design accuracy requirements

[0007] During the frequent opening and closing of the high-pressure common rail injector, the sealing steel ball 64 repeatedly contacts and separates with the throttle cone 73 along with the moving spool 62. During this movement, the sealing steel ball 64 and the joint The actual sealing line formed by the contact of the flow cone hole 73 is constantly changing. Since the surface roughness, surface hardness, roundness and straightness of the flow cone hole 73 are difficult to meet the design requirements, it is difficult to ensure the opening and closing of the two. Reliability; in the process of frequent opening and closing, the sealing steel ball 64 itself will rotate and easily deform, which will lead to unstable sealing; due to the high oil pressure of the system, the high-pressure oil beam continuously washes the throttle cone when it is in the open state The cone surface of the hole 73 will be washed out for a long time to form irregular fine shallow grooves, resulting in a decrease in sealing performance; in addition, the sealing steel ball 64 is installed in the center hole of the lower end surface of the movable valve core 62, and the throttling The tapered hole 73 is set on the upper end surface of the pilot valve seat 71, and the axis of the two always deviates, which is easy to produce unilateral contact, thus affecting the sealing performance of the closure

[0008] Through the above objective analysis, it can be seen that in the existing high-pressure common rail injector for diesel engines, the design of the sealing structure between the control valve coupler 6 and the valve assembly 7 is unreasonable, the technical requirements for the throttling cone hole 73 are high, and the processing is difficult. Conventional grinding machines cannot be used for processing, and the introduction of the entire production line requires a large investment, which is difficult for domestic general oil pump nozzle manufacturers. Even if the entire production line is introduced, the operator's technical level is difficult to adapt

This kind of sealing structure will inevitably lead to low product yield, poor sealing stability, short service life, high product price, and unbearable for users.

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