Diesel Distributor Fuel-Injection Pumps VE - Gnarlodious

Design and constructionThe hydraulic cold-start acceleratorcomprises a modified pressure-controlvalve, a KSB ball valve, a KSB controlvalve, and an electrically heated expansionelement.Method of operationThe fuel delivered by the fuel-supplypump is applied to one of the timingdevice piston’s end faces via the injectionpump’s interior. In accordance with theinjection pump’s interior pressure, thepiston is shifted against the forceof its spring and changes the startof-injectiontiming. Pump interiorpressure is determined by a pressurecontrolvalve which increases pumpinterior pressure along with increasingpump speed and the resulting rise inpump delivery (Fig. 15).There is a restriction passage in thepressure-control valve’s plunger in orderto achieve the pressure increaseneeded for the KSB function, and theresulting advance curve shown as adotted line in Fig. 16. This ensures thatthe same pressure is effective at thespring side of the pressure-controlvalve. The KSB ball-type valve has acorrespondingly higher pressure leveland is used in conjunction with thethermo-element both for switching-onand switching-off the KSB function, aswell as for safety switchoff. Using anFig. 15Hydraulic cold-start accelerator (KSB)11 Pressure-control valve,12 Valve plunger,13 Restriction passage,14 Internal pressure,15 Fuel-supply pump,16 Electrically heatedexpansion element,17 KSB ball valve,18 Pressureless fuel return,19 KSB control valve,adjustable,10 Timing device.Effect of the hydraulic cold-startaccelerator (KSB)1 Injection-timing advance.adjusting screw in the integrated KSBcontrol valve, the KSB function can beset to a given engine speed. The fuelsupply pump pressure shifts the KSBcontrol valve’s plunger against theforce of a spring. A damping restriction isused to reduce the pressure fluctuationsat the control plunger. The KSBpressure characteristic is controlled byits plunger’s control edge and the sectionat the valve holder. The KSB functionis adapted by correct selection of theKSB control valve’s spring rate and itscontrol section. When the warm engineis started, the expansion element hasalready opened the ball valve due to theprevailing temperature.1234°cmsInjection-timing advance51Pump speed p786min –1UMK0379EFig. 16Add-onmodulesand shutoffdevices109UMK1195Y43