The Robert Bosch

7/26/2019 The Robert Bosch

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The Robert Bosch

VE-Type

Distributor PumpThe Robert Bosch VE-type injection pump is used on a variety of vehicles and is made under

licenses by other manufacturers ( Diesel Kiki and Nippondenso). The Bosch VE pump is

primarily found on compact and automotive diesel engines. The code designation on the side of the pump is read:

Example: NP-VE x/x F xxxx A R NP xx

NP These to letters stand for the manufacturer! in this case! "iesel #i$i

VE "istributor-type inje%ction pumpx number of cylinders

x plunger diameter in millimeters

F mechanical governor

xxxx governor-controlled R&' number

A design symbol

R direction of rotation ( R for cloc$ise! L for countercloc$ise

NP xx production serial number

Main Components

)t is necessary to become familiar ith the main components of the VE-type injection pump tounderstand the basic operating principles. Refer to *igures + and , for the location of the main

components.

VE pump may be gear or spur-belt driven. The drive shaft is connected to a cam plate (# ith

a driving dis$ ()! figure ,. The drive shaft! cam plate! and plunger all rotate together. ote thehigh spots on the cam plate. These high spots are the face cams and the number of face cams

e/uals the number of engine cylinders. s the cam plate rotates! the face cams contact the rollers

causing the cam plate and plunger to move bac$ and forth in the plunger bore. 0pring pressureholds the cam plate and plunger agains the rollers. The drive shaft also drives the fuel-supply

pump (1 and the governor flyeight drive gear (2.

t the bottom of the injection pump is the automatic advance-timing device. s fuel-supply

pump presure increases the piston moves the roller ring opposite to driveshaft rotation!advancing injection timing. 'ounted outside the distributor head is a delivery valve ( for each

cylinder! fuel-cut (fuel shutoff solenoid! and an air-bleed scre in the center.



t the top of the injection pum is a control lever (3! a control-lever shaft ("! and an overflo

(retun fuel valve. Engine idle R&' and ma%imum speed can be adjusted by the idle-speed

adjusting bolt and ma%imum-speed adjusting bolt.

4nder the top cover is the governor mechanism.

F!"RE #$ Cuta%ay o& VE in'ection pump sho%in( component )ocation*

(Courtesy of General Motors Corporation Produt !er"ie #rainin$)

F!"RE +$ Cuta%ay o& VE in'ection pump


http://mebonty.monobasin.net/figure_2_lg.png




Fue)-,upp)y Pump

t the driveshaft end of the injection pump is a positive displacement! vane-type fuel-supply

pump! *igure 5. )t (sometimes ith an additional outside-supply pump is used to bring fuel fromthe tan$ and send pressuri6ed fuel to the distributor plunger and the injection timing advance

mechanism. E%cess fuel is used to cool and lubricate the injection pump.

F!"RE $ Fue) &)o% throu(h supp)y pump

(Courtesy of General Motors Corporate Produt !er"ie #rainin$)

otice that the inside diameter of the supply-pump housing is eccentric (offset to the center of the rotor. s the rotor turns! the volume beteen the vane segments changes. 7here volume

increases is the suction (inlet side. 7here volume decreases is the pressuri6ed (outlet side.

0upply pump output volume and pressure increase as pump speed increases. 0ince displacementand pressure of the transfer pump can e%ceen injection re/uirements! some of the fuel is

recirculated to the inlet side of the supply pump by a regulating valve.

0tarting from the bottom! as the pump rotates the volume increases beteen the vanes. The

increasing volume dras fuel into the supply pump. s the rotor continues to turn! a vane illuncover the outlet port. otice that the volume beteen the vanes is decreasing! pressuri6ing the

fuel. This pressuri6ed fuel is then governed by the regulating valve.




Re(u)atin( Va).e peration

*uel from the outlet of the supply pump forces the piston (3 bac$! compressing the regulating

spring! *igure 8. s fuel flo from the supply pump increases! the piston is pushed further bac$ alloing more fuel to be bypassed bac$ to the inlet side. The speed of the supply pump and

regulating-valve-spring pressure determine ho much fuel ill be bypassed. )t is important thatthe supplyu pump provide the correct pressure for the timing advance and fuel feed for the

distributer plunger.

F!"RE 0$ Re(u)atin( .a).e

P)un(er peration

To understand ho this pump pressuri6es and distributes fuel one must be aare that the plungerhas to motions: simultaneously reciprocating and revolving! *igures 9 and . s the high spots

move off the rollers! pressuri6ation stops as the plunger reverses! alloing fuel to be drn in for

the ne%t stro$e. )t is the reciprocating motion that pressuri6es the fuel and the rotating motion ofthe planger that distributes it.

F!"RE 1$ P)un(er2 hea32 an3 cam-p)ate assemb)y





F!"RE 4$ t is important to un3erstan3 that the p)un(er reciprocates an3 rotates at the

same time

nta5e ,tro5e

7hen the inta$e slit (opening on the plunger! *igure ;! aligns ith the inta$e port during the

plunger inta$e stro$e! fuel pressuri6ed by the fuel-supply pump flos into the high-pressurechamber. The number of inta$e slits e/uals the number of cylinders.




F!"RE 6$ nta5e ,tro5e


)njection 0tro$e

&lunger rotation moves the inta$e slit out of alignment ith the inta$e port and aligns the

distributing slit ith the outlet passage! figure <. 7ith the inta$e port closed! fuel is trapped in

the high-pressure chamber. The plnger is also moving into its bore! pressuri6ing the fuel. The pressuri6ed fuel pushes the delivery valve off its seat and fuel is injected into the combustion

chamber of the engine through the no66le.

F!"RE 7$ Be(innin( o& in'ection stro5e






End of "elivery

s the plunger continues moving into the bore! *igure =! the cutoff port moves past the control

sleeve. The high-pressure fuel escapes into the pump housing! reduces the pressure! and ends fueldelivery to the injection no66le.

F!"RE 8$ En3 o& 3e)i.ery


E/uali6ing 0tro$e

The e/uali6ing stro$e occurs as the plunger continues to rotate after the end of the delivery!

*igure +>! an e/uali6ing slit +<> degrees opposite the distributing slit aligns ith an outlet passage. This causes the pressure in the passage to the delivery valve to be restored to the feed

pressure. This insures that all outlet passages have the same pressure to maintain smooth engine performance.

F!"RE #9$ E:ua)i;in( ,tro5e


Reverse-Rotation &revention

)t is possible for the diesel engine to start in the reverse (opposite direction of normal operation.The VE pump does not allo this to happen! *igure ++. )f the plunger ere to rotate in the

reverse direction the inta$e port ould open during the injection stro$e! preventing any pressure

buildup.





F!"RE ##$ Re.erse Rotation Pre.ention


*uel 'etering

*uel is metered by the movement of the control sleeve in relation to the plunger cutoff port!

*igure +,. 'oving the control sleeve changes the effective stro$e. The effective stro$e is the

period at hich fuel is pressuri6ed at injection pressure. The longer fuel is pressuri6ed at

injection pressure! the longer the effective stro$e. 0o! the longer the control sleeve covers thecutoff port! the longer the effective stro$e! and more fuel is injected. t idle the control sleeve is

more to the left! providing a short! effective stro$e. s more fuel is needed to meet demand! the

control sleeve ill move further up the plunger! increasing the effective stro$e. ote that themechanical stro$e of the plunger remains the same.

F!"RE #+$ E&&ecti.e P)un(er ,tro5e


"elivery Valve

7hen the plunger pressuri6es the fuel! fuel pressure overcomes delivery-valve spring pressureand the residual line pressure and pushes the delivery valve off its seat! *igure +5 part . 7hen

pressure drops and injection ends! the pressure in the injection line and spring pressure move the

delivery valve and piston! *igure +5 part B. The piston first closes off the injection line. The

period from hen the piston closes the injection line until the delivery valve seats is called the

retraction stro$e. This creates more volume! hich decreases pressure in the injection line. Theretraction stro$e prevents cavitation and unanted secondary injection by dampening high-

pressure aves.

F!"RE #$ De)i.ery-.a).e Action


1overnor

variable-speed governor and a minimum?ma%imum (min-ma% governor are available ith this pump! depending on application. *igures +8 and +9 sho the parts of a min-ma% governor. @i$e

all mechanical governors! there is balance crated beteen spring tension and force generated by

flyeights. s flyeight R&' increases! force on the levers increases. These forces! plus the

setting determined by the operator! determin the position of the control sleeve! *igure +.

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F!"RE ++$ ,pee3-timer operation






0tarting

"uring starting! *igure +;! the flyeights are at rest and the starting spring has moved thestarting lever and control sleeve for the ma%imum effective stro$e. This ill supply enogh fuel to

start the engine. 7hen the engine starts! the flyeights move out! compressing the starting spring

and shortening the effective stro$e.



)dling

"uring idle! ith the control lever in the idle position! the start-idling spring and the starting

spring are in balance ith the force from the flyeights! *igure +<! and the control sleeve hasmoved! reducing the effective stro$e during starting. )f idle speed drops! spring pressure ill

move the control sleeve! increasing the effective stro$e. )f idle speed increases! the flyeights

ill move the control sleeve to reduce the effective stro$e.



&artial @oading

7hen the control lever is moved off idle by the operator! by cable through a lever or by

accelerator pedal! more fuel is needed! *igure +=. Essentially! this action compresses the damperspring! moving the control sleeve and increasing the effective stro$e.










*ull-@oad 'a%imum 0peed

The control lever is in the full-load ma%imum-speed position hen it touches the e%ternal

ma%imum-speed stop bolt! *igure ,>. The springs opposing the flyeights are commperssed!

moving the control sleeve and providing the largest effective sto$e e%cept for starting.

o-@oad 'a%imum 0peed

)f the engine speed e%ceeds the full-load ma%imum speed! the flyeights no e%ert enough forceto move the control sleever! reducing the effective stro$e and preventing fuel from being injected

into the cylinder! *igure ,+.

)njection-timing dvance

t the bottom of the injection pump is the automatic-advance timing device. s fuel-supply pump pressure increases! the piston moves the roller ring opposite to drive shaft rotation!

advancing injection timing! *igure ,,. s engine speed increases! fuel pressure from the vne

pump also increases. This allos the timer piston to overcome thetimer spring! causing the roller

housing to move opposite cam-plate rotation. The rollers then engage the cam-plate high pointsearlier! advancing injection timing.

3old-0tart "evice - 30" ('anual

The cold-start device advances injection timing at idle and during lo-speed running. lever

turns a cam that pushes the hydraulic piston to the left! advancing injection timing about fivedegrees! *igure ,5. This injection advance provides more time for the fuel to burn! hich

improves performance and prevents smo$ing during cold starts and arm-up.

The cold-start cam does not advance the complete range of injection timing. bove ,,>> R&'

the piston operates normally and does not contact the cam.



F!"RE +$ Manua) co)3-start a3.ance )e.er

(Courtesy of %olks&a$en of 'meria n.)

3old-0tart "evice - 30" (utomatic






There are different types of automatic 30"s available for the VE injection pump. Ane popular

type is the vacuum-operated 30" that uses a vacuum pump! ater thermo valve! and a dual-

stage diaphragm located on the injection pump! *igure ,8. The thermo valve! *igure ,9! appliesvacuum to the diaphragm(s! depending on coolant temperature. (*igure , shos hich

diaphragms have vacuum applied at various temperatures.

nother 30"! called the #0B (a Bosch designation! advances injection timing by controlling

supply-pump pressure. #0B control valvemounted on the side of the pump overrides the pressure regulator! increasing supply-pump pressure and advancing injection timing. *or

e%ample! if the temperature is belo the set value of the temperature sitch! the sitch closes

and the #0B solenoid sitches on. This increses pump pressure. bove a preset value! thetemperature sitch opens! the #0B solenoid opens! and the pressure regulator no controls

supply-pump pressure.

F!"RE +0$ Vacuum-operate3 C,D

(Courtesy of ord Motor Company)

F!"RE +1$ Thermo Va).e


T<ERM VA=VE TEMPERAT"RE DAP<RA!M F"NCTN TMN! ADVANCE

Belo 89*

(;30tage + C 0tage , < degrees

89-<*

(;-,>3 0tage + 9 degrees

bove <*

(,>3 one

one

(D T"3

F!"RE +4$ C,D 3iaphra(m operation


neroid 3ompensator

The VE-Type pump can be e/uipped ith an aneroid compensator to loer emissions! *igure ,;.

The aneroid compensator! mounted on the top of the VE pump! modifies the fuel control toadjust for changes in altitude. s altitude increases! atmospheric pressure decreases. This allos

the bellos to e%pand! pushing the adjusting rod donard. This motion is carried through the

pin! lever! and tension lever to the control sleeve. The control sleeve is moved toard the drive-

end! decreasing the effective stro$e.





F!"RE +6$ Aneroi3 compensator


ir *uel 3ontroll (*3 Valve

The *3 valve (also called a boost-pressure-enrichment device is added to the fuel-injection

pump on engines e/uipped ith a turbocharger. s the turbocharger adds more air to the

cylinders! more fuel must be supplied. )n *igure ,<! note the position of the diaphragm!

diaphragm push-rod! bell cran$! and control ring. s boost pressure increases! the diaphragm isforced donard! changing the position of the bell cran$! *igure ,=. The control sleeve (ring

moves further to the right! increasing the effective (or$ing stro$e and the amount of fuel that is

injected into the cylinder.

F!"RE +7$ Boost pressure enrichment 3e.ice(Courtesy o %olks&a$on of 'meria* n.)

F!"RE +8$ Diaphra(m pushe3 3o%n%ar3 by boost pressure2 increasin( e&&ecti.e stro5e

(Courtesy of %olks&a$en of 'meria* n.)

*uel-3ut 0olenoid

The fuel-cut solenoid! controlled by the ignition sitch! *igure 5>! opens or closes the fuel-

inta$e passage to the fuel-cut solenoid valve! the inta$e passage is open! alloing fuel to enterthe high-pressure chamber. 7ith no current to the solenoid! the spring-loaded valve closes off the

inta$e port preventing fuel flo. 0ome VE pumps may have a manual shutdon lever mountedon the side! in case the fuel-cut does not shut off the engine.

F!"RE 9$ Fue)-cuto&& so)enoi3 operation


0ervicing The VE )njection &ump

s ith other injection pumps! certain precautions hold true for the VE injection pump. Breiflystated! they are:

• 3leanliness

• ll fastners tor/ued to specifications

• 4se of manufacturers special tools or e/uivilent







This pump is used by several engine manufactures and the injection pump is built by

manufacturers under license from Robert Bosch. lays consult the service manual specific to

the e/uipment or vehicle you are or$ing on. )t ill state hat pump service procedures andadjustments can be made in the field.

The folloing procedures are meant only as a guide to e%plain the procedures. 4se the detailedservice procedures given in the service manual.

&ump Removal and )nstallation

This tas$ re/uires the folloing

• ppropriate hand tools

• 'anufacturers special tools

• 'ar$ing pen or scribing tool

• manufacturers service manual

Remo.a)* 3arefully clean and ipe the injection pump and surrounding area.

CA"TN$ 'ar$ the injection pump mounting flange to the timing case or brac$et. This ill

help preserve injection pump timing.

)f the injection pump is belt driven! remove the belt cover.

CA"TN$ 'ar$ the belt to the injection pump gear! camshaft gear! and cran$shaft gear. This

ill help ensure that all components are timed properly.

"isconnect the throttle lin$age and fuel cutoff solenoid ore. )dentify! disconnect! and remove

the fuel injection lines. 3ap all e%posed openings.

"isconnect the remaining fuel lines and remove the injection pump from the pump gear. (0pecialtools may be re/uired to perform this tas$. Be careful not to drop any parts inside the timing

case. Remove the injection pumps attaching nuts and bolts to remove the pump.

nsta)ation* ttach the pump to the engine and line up the timing mar$s. Tighten the attachingnuts and bolts. 3onnect the injection pump to the pump gear and connect all fuel lines and

injection lines. Then install the throttle lin$age and fuel cutoff solenoid ire (chec$ the throttle

lin$age to be sure it does not bind or stic$.

Be sure that all timing mar$s are lined up! attach the timing belt and adjust tension. Bleed airfrom the injection pump according to manufacturers instructions.

)dle 0peed djustment

This tas$ re/uires the folloing:



• pproprate hand tools

• 0pecial tachometer

• 'anufacturers service manual

0ince the VE pump is used by several engine manufacturers! there are different methods and

tachometers used to set idle speed. )t may be necessary to use the magnetic probe-type! or the

vibration sensor-type to measure engine R&'.

• The magnetic probe type uses a variable reluctance sensor to determine cran$shaft R&'s.

The sensor probe uses a permanent magnet and a coil of ire. s a tooth or notch passes

by the probe! the magnetic field e%pands and collapses. This induces an 3 voltage in the

coil. The tachometer converts this 3 voltage into engine R&'s.

• The photoelectric system shines a beam of light onto reflective tape mounted on the

cran$shaft pully! *igure 5+. The beam of light reflects off the tape to a sensor mounted in

the tachometer. The engine R&' measurement is then read off a meter. )t is important

that the pulley flange is clean and that the tachometer does not pic$ up stray reflections.

• The vibration sensor mounts on thop of the valve cover! *igure 5,. R&' signals are

generated by the sensor and sent to the tachometer here engine R&' measurements are

read.

Before starting the idle speed adjustments! prepare the vehicle according to manufacturers

instructions. This usually means ith the engine fully armed up and all accessories off.

Chec5 3)e ,pee3* To adjust idle speed! loosen the idle speed loc$ nut and turn the idle-speed

bolt to achieve the desired reading! *igure 55. Tighten the loc$ing nut and rechec$ idle speed.

2igh 0peed djustment

This tas$ re/uires the same tools used in setting idle speed. (Be sure the manufacturer states that

this adjustment can be doneF otherise! do not do it.

CA"TN$ Be certain the vehicle has the par$ing bra$e set and the heels bloc$ed. 'a$e sure

all accessories are off.

7ith the tachometer connected and the engine at operating temperature! briefly accelerate the

engine to full-load position and note the tachometer reading. )f necessary! adjust the high-speed

scre to manufacturers specifications (see *igure 58. "o not e%ceed the specified speed or

engine damage could result.

djusting the Throttle &osition 0ensor (T&0

T&0 is used by some manufacturers to control emissions and?or automatic transmission shift

points. )f the T&0 has moved or has been ta$en off! it must be chec$ed and adjusted as necessary.





• "igital volt-ohm meter ("VA'

• manufacturers service manual

3onnect the "VA' as shon in the service manual. Typically! you ill be as$ed to measure

T&0-signal voltage. )f the voltage signal is out of range! adjust theT&0 as outlined in the shop

manual.

)njection &ump Timing



• 'anufacturers special tools (static-timing adapter! dial indicator

• 'anufacturers service manual

VE injection pump timing is performed ith the engine off. "espite the fact that it is used byseveral engine manufacturers! the timing process is basically the same. 7hat must be measured

is the amount of injection pump plunger travel at a specific point (usually engine T"3! *igure

59.

&repare the vehicle according to the service manual. 3hec$ to be sure valve timing and timing belt tension are properly set. Remove the scre plug in the hydraulic head and mount the static

timing adaptor in the pump! *igure 5. Rotate the cran$shaft to the specified reading! then rotate

the cran$shaft (usually countercloc$ise until the dial indicator stops moving. Gero gauge the pointer and rotate the cran$shaft cloc$ise to the specified position and note the dial indicator

reading! *igure 5;. (The reading should be ithing specifications. )f it is less than specified!timing is retarded. 1reater than specified! timing is advanced.

)f it is necessary to adjust the timing! loosen the pump mounting nuts (bolts and rotate the pumpto the desired reading. Tighten the nuts (bolts and chec$ timing. Be sure to remove special tools

and replace the scre plug. install any other components removed. 3hec$ the idle speed and

adjust if necessary.

0ummary

The Robert Bosch VE injection pump! made by a variety of manufacturers under license! is

primarily found on small! high-speed diesel engines. )t can be tailored to meet specific engineneeds.

This pump uses a single plunger that rotates and reciprocates simultaneously. The amount of fuelinjected is determined by the effective stro$e of the plunger. 3are is needed hen performing

service on this pump. "o only the service stated by the manufacturer.

The Robert Bosch

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