Low pressure difference hydraulic sealing type high-pressure common-rail fuel pump

Abstract

The invention relates to a low pressure difference hydraulic sealing type high-pressure common-rail fuel pump which mainly comprises a pump body, a plunger piston, a fuel outlet check valve, a fuel inlet check valve, a low differential pressure control valve, a synchronous pressure lifter and a lubricating oil inlet check valve. The low differential pressure control valve and the synchronous pressure lifter are used for controlling the synchronous pressure rise and reduction of a lubricating end and a fuel end of a fit clearance between the plunger piston and an operating cylinder, and the lubricating oil pressure is maintained to be slightly higher than the fuel pressure so as to prevent fuel from flowing into the fit clearance between the plunger piston and the operating cylinder. The invention solves the problem of high-pressure fuel leakage, the fuel pressure is higher than 2200 bar, the lubrication of the precise sliding fit surface between the plunger piston and the operating cylinder is ensured, the reliability and the durability of operation are increased, fuel consumption and emission can be further reduced for an ultrahigh-pressure fuel injection system, and the fuel pump can be applied to low-viscosity alternative fuels such as diesel engine dimethyl ether and the like.

Description

Technical field: [0001] The invention belongs to the technical field of internal combustion engines. The invention mainly relates to a high-pressure common-rail fuel injection device for a diesel engine, in particular to a low-pressure differential hydraulic seal high-pressure common-rail fuel pump. technical background: [0002] Diesel engine has high thermal efficiency and has become a widely used engine. The fuel injection system of a diesel engine is a key component that affects the fuel consumption rate and emissions of a diesel engine. In order to reduce the fuel consumption rate and emissions, countries are constantly improving it. Since the birth of a diesel engine in 1892, its fuel injection system has been replaced by a mechanical fuel injection system. , The first generation of cam pressure oil position controlled electronically controlled fuel injection system and the second generation of cam pressure oil solenoid valve controlled electronically controlled fuel ...

AI Technical Summary

Problems solved by technology

[0004] The applicant's utility model patent (patent number: ZL 2006 1 0127615.1) "Multi-fuel Diesel Engine Fuel Injection Pump" adopts an oil groove on the plunger sleeve and uses high-pressure lubricating oil to seal and lubricate the gap between the plunger and the plunger sleeve. As the plunger goes down to absorb oil and pumps up, the oil pressure of the fuel in the cylinder on the top of the plunger keeps rising and falling, and the alternating pressure difference exceeds 1000bar. When the lubricating oil enters the fuel, there will be problems of burning engine oil and blocking the injection hole of the injector. When the oil pressure of the lubricating oil is lower than the changing fuel oil pressure, low-viscosity fuel such as dimethyl ether enters the gap between the plunger and the plunger sleeve. Problems with wear and fuel leaks

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