Constant-volume metering pump

Abstract

The invention provides a constant-volume metering pump. The constant-volume metering pump comprises a pump body, a solenoid device and a plunger pump, wherein the solenoid device and the plunger pump are located in the pump body. The solenoid device comprises an armature. The plunger pump comprises a sleeve, a plunger, an input valve and an output valve. The sleeve comprises a sleeve inner hole, and the sleeve inner hole is in close fit with the outer surface of the plunger and can slide freely. The interior of the pump body is divided into a low pressure space and a pressure feed space by the plunger pump. Liquid enters the pressure feed space from the low pressure space through the input valve, and then is discharged through the output valve. The constant-volume metering pump is characterized in that the sleeve and the armature are connected and kept reciprocating synchronously, the solenoid driving device drives the sleeve and the plunger to move relatively to enable the liquid to be discharged, and the liquid discharging amount obtained through relative movement between the sleeve and the plunger is limited by the geometric structure.

Description

technical field [0001] The invention belongs to the field of liquid metering technology, especially the liquid injection metering technology related to engine exhaust post-treatment, and specifically relates to a selective catalytic reduction (SCR) system for purifying engine exhaust gas and nitrogen oxides selective catalytic reduction (SCR) system for diesel engine exhaust particulate matter filtration and collection (DPF). Fuel injection regeneration system. Background technique [0002] Engine exhaust purification Nitric oxide selective catalytic reduction (SCR) system and exhaust particulate filter (DPF) system are not only very important for diesel engines, but also have application value for in-cylinder direct injection gasoline engines, both of which involve liquid injection and metering. [0003] Nitrogen oxide selective catalytic reduction (SCR) system needs to spray 32.5% urea water liquid quantitatively into the engine exhaust system. The urea water liquid decomp...

AI Technical Summary

Problems solved by technology

The disadvantage of the metering device is that the plunger is connected head to tail with the armature, the axial dimension is longer, and the moving mass is relatively large. If the friction is provided by the cooperation of the plunger-sleeve, the center of gravity of the moving part will be at In addition to the support friction, the inertia of motion will affect the durability; if a sliding support of the plunger (that is, the magnetic sleeve, MAGNET SLEEVE 67) is arranged at the other end of the spring opposite the sleeve, or a sliding support of the armature is arranged For support, it is necessary to strictly control the coaxiality of the sleeve and the sliding support, which is difficult to manufacture, especially between the sliding support of the plunger and the spring, an additional spring seat (snap ring 68) needs to be arranged, and the installation of the spring seat The process is also more complex

In addition, due to the relatively large mass and friction of the moving parts, the frequency of the plunger's reciprocating motion will be limited

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