Detailed VE Pump info..Updated Feb.12/03

[BushWakr - RIP]

Detailed VE Pump info....

I have pasted, in 3 parts, the following text file on the VE pump. It was compiled by another 1st Genner who has given his permission to copy and use on our site. The credit goes to OkieBronkrider, moderator on the DTR site... thanks 'Okie. .



Let me apologize in advance for being presently unable to post accompanying pictures that are referenced in this excellent post.





Unlike Delphi, Lucas or Stanadyne pumps. The rollers on the VE pump are not actuated by an internal cam ring with lobes on it, but instead the cam ring circular and attached to a round cam plate. As the cam ring rotates with the injection pump driveshaft and plunger, the rollers (which are fixed), cause the cam lobe to lift every 60* in a six cylinder engine. In other words, the rollers do not lift on the cam as in a conventional system, but it is the cam ring that is solidly attached to the rotating plunger that actually lifts as each lobe comes into contact with each positioned roller spaced apart in relation to the number of engine cylinders. With such a system then, the plunger stroke will remain constant regardless of engine rpm. At the end of each plunger stroke, a spring ensures a return of the cam ring to its former position. Therefore, the back and forth motion of the single pumping plunger is positive.



The sequence of events in a VE pump. The fill slot of the roatating plunger is aligned with the fill port, which is recieving fuel at transfer pump psi as high as 7 bar (100psi), one cylinder only.



The rotating plunger has reached the port closing position. The plunger rotates a control spool regulating collar. The position of the regulating collar is controlled by the driver through linkage connected to and through the governer spring and flyweights. Therfore, even though the roller may be causing the cam ring plunger to lift, the position of the regulating collar determines the amount of travel of the plunger or prestroke, so the actual effective stroke of the plunger is determined at all times by the collar position.



As the point of plunger lift (start of effective stroke), fuel delivery to the hydraulic head and injector line will begin in the engine firing order sequence.



The effective stroke is always less than the total plunger stroke. As the plunger moves through the regulating collar, it uncovers a spill port, opening of the high pressure circuit and allowing the remaining fuel to spill into the interior of the injection pump housing. This then is port opening or spill, which ends the effective stroke of the plunger



With the sudden decrease in fuel delivery psi, the spring within the injector nozzle rapidly seats the needle valve, stopping injection and preventing after-dribble, unburned fuel, therefore engine exhaust smoke. As the same time, the delivery valve for that nozzle located in the hydraulic head is snapped back on its seat by spring psi.



One thing to always remember is that the force of the governor spring is always attempting to increase the fuel delivery rate to the engine, while the centrifugal force of the governor flyweights is always attempting to decrease the fuel to the engine. Anytime that the centrifugal force of the rotating governor flyweights and the governor spring forces are equal, the governor is said to be in a state of balance and the engine will run at a fixed steady speed. ...



Continued .....



Bob

 

[BushWakr - RIP]

continued from above post.....



Engine Acceleration revised:



When the engine is accelerated beyond the idle rpm, the centrifugal force of the roatating governor flyweights will force the sliding sleeve to the right and with the starting lever up against the tensioning lever, the idle spring will be compressed. Additional engine speed and weight force will now cause lever to pul against the larger governor spring. Movement of the throttle lever causes the engine speed control lever to move away from the idle speed adjusting screw and toward the full load screw. The travel of the speed control lever is determined by the driver and just how fast he or she wants to go . When the driver stomps on the throttle, the previous state of balance condition that existed at idle is upset in favor of the gov spring. The control spool is moved through the starting lever and the tensioning lever so that the effective stroke of the rotating pump plunger is lengthened by moving the control spool initially to its right. As the engine recieves more fuel and accelerates, the centrifugal force of the rotating flyweights will push the sliding sleeve to its right causing the starting lever and the tensioning lever to stretch the governor spring. When a state of balance condition exists once again between the rotating weights and the spring, the engine will run at a steady speed with the throttle in a fixed position. If the throttle is placed in full fuel, the speed control lever will butt up against the full load adjusting screw, which will limit the maximum speed of the engine. Weight force at this point is greater than the spring force, therefore, the sliding sleeve will cause the starting and tensioning lever to PIVOT around the support pin. The control spool will be moved to the left which will reduce effective stroke of the rotating pump plunger. As a result, the engine will recieve less fuel, therby automatically limiting the maximum speed of the engine. When the centrifugal force of the rotating governor flyweights are exual to the governor spring force the engine will run at a fixed RPM at max speed. If the engine was started and accelerated to its max rpm with the vehicle in a stationary position, the action of the governor weights would limit the maximum amount of fuel that the engine could recieve by moving the contol spool to decrease the pump plungers effective stroke. When the engine is running under such a condition (max no load speed) it is not receiving full fuel.



The reaction of the governor when a load is applied to the engine will always be the same at any speed setting.

Description: Load applied at a given speed setting of the throttle, and engine slows down such as when going up a hill.

Upsets state of balance between weights and governor spring when above idle speed, if at idle, spring in favor of the spring force.

Spring pressure is greater and therfore the starting and tension lever move the the control spring to its right to lengthen the effective stroke of the rotating pump plunger and supply the engine with more fuel to develop additional HP.

If the load on the engine continues to increase, the engine will recieve more fuel to try to offset the load, but is will run at a slower RPM.

As long as the engine can produce enough additional hp, the governor will once again reach a state of balance between the weights and the spring, but at a slower speed than before the load was applied.



When the load was applied, the spring expanded (lengthened) to increase the fuel to the engine and, in so doing, lost some of its compression; therefore the weights do not have to increase their speed/force to what existed before to establish a new state of balance. The engine will produce more hp with more fuel but will be running at a slower RPM.

Regardless of the governors reaction to increase fuel to the engine, if the load requirements exceed the power capability of the engine, the rpm will continue to drop. In our trucks, the only way that the speed can now be increased is for the driver to select a lower gear by downshifting.

If the engine was running at an idle rpm and the air conditioner pump was turned on, the engine would tend to slow down (load increase). the governor through the spring force/less weight force would increase the fuel to the engine to prevent from stalling.



Continued in next post.....

 

[BushWakr - RIP]

continued from last post. . last series. .



Engine Decrease:



Engine speed decreases, weights fly out with more force and they will cause the sliding sleeve to move the starting and tensioning levers against the force of the spring.

The control spool will move to its left to decrease (shorten) the effective stroke of the pump plunger and reducde fuel to the engine until a new corrected state of balance condition exists.

With load on the engine, it requires less hp and less fuel and as the engine slows down, so do the weights until the state of balance is re-establishied.

If a vehicle goes down a hill, the load is reduced. If the driver does not check the speed of the truck, it is possible for the driving wheels to run faster than the engine. IF the drive wheels starte to rotate the engine, the governor weights will also gain speed and by doing this, they will reduce the effective stroke of the pump plunger and the engines fuel will automatically be reduced.



High speed control:



When the engine speed and therefore governor weight force is great enough, the centrifugal force of the weights will oppose the high speed spring until a state of balance occurs. When the weights and spring come into play at the higher speed range, the maximum speed of the engine is limited by the fact that the weights as they fly out cause the sliding sleeve to transfer motion through lever and which will compress the spring and therefore move the control spool to its left to shorten the effective stroke of the pump plunger. In this way, the engine receives less fuel and the masimum speed of the engine is therefore limited when the weights and spring are in a state of balance.



The aneroid boost head compensator control (AFC):



Basically, the boost compensator ensures that the amount of injected fuel is in direct proportion to the quantity of air within the engine cylinder to sustain correct combustion of the fuel and therefore increase the hp of the engine. With the engine running, pressurized air from the cold end of the turbo passes through the connecting tube from the engine air manifold to the boost compensator chamber. Inside this chamber is a diapraghm which is connected to a pushrod (eccentric cone) which is in turn coupled to the pin. Movenment of the diapraghm is opposed by a spring, therefore for any movement to take place at the pin, the air psi on the the diaphraghm must be higher than spring tension. As the engine RPM and load increase and the air psi within the connecting tube becomes high enough to overcome the tension of the spring, the diaphragm and pushrod will be pushed down. This movement causes the compensator pin to come in, forcing the fuel contol rack toward an increased fuel position. The boost compenstor will react to the engine inlet air psi regardless of the action of the governor. When the turbo boost reaches its maximum, the quantity of additional fuel is injected will be equal to the stroke of the aneroid boost compensator pin, in additon to the normal full load injection amount that is determined by the governor full load stop bolt.



>>>

Pictures from the Bosch VE manual (which can be purchased on-line as a .pdf document from SAE for ~$15). I am guessing from the discussion on this thread that you all might find it interesting, despite its length.



. . . but I will re-hash my analysis of the pump operation here. (The figures in the manual on pages 22 (Fig. 1)and 37 (Fig. 7) will be helpful for the following discussion).



There are two adjustments that control the maximum fuel delivered by the pump. The first is the "Full-load adjusting screw" (Fig 7 # 10). It can also be seen in the upper right on Fig. 1 pg. 22. As far as I can tell, it rotates a static lever (fig 7 #11) around a fixed fulcrum. The top of the lever rides on the adjusting screw and the bottom has the fulcrum for the

"tensioning lever" (Fig. 7 # 12, but more plainly visible in fig 1).

Adjusting the "power screw" moves the fulcrum for the tensioning lever back and forth, and the position of the tensioning lever controls the slip collar on the piston, which controls when the piston spill ports open (ending fuel delivery for that stroke). Turning the screw in moves the tensioning lever fulcrum to the right (as pictured), and thus the slip collar to the right. This is why over-adjustment of the full-load screw results in high idle, and eventually erratic governor operation. The second adjustment is through the AFC. The AFC assembly controls the "Reverse lever" (Fig 7 #3) which acts as an adjustable stop for the travel of the "tensioning lever". (the following references are to fig. 7) As pressure increases on #14 #8 moves down, letting #4 slide to the right, #3 rotate clockwise, and # 12, the tensioning lever, move further to the left (as pictured).



By changing the orientation of the "Sliding pin's" "control cone" you can change how far out into the AFC bore the "guide pin" extends, and thus the stop position for the tensioning lever. The further out the "guide pin" is allowed to extend into the bore, the more fuel you get. On my pump, I observed that with the "sliding pin" removed, the "guide pin"

would extend out farther into the bore than even the narrowest part of the sliding pin would allow, and that the pump would operate properly with the guide pin extended this far. Running the pump with the "control cone" set in the maximum fuel position, I find that I produce too much smoke at manifold pressures under about 3psi.



So, ideally I would have a "control cone" with a taper that started from no detent, and continued to a detent that was as deep as the guide pin will extend (with the sliding pin out, and the accelerator floored -- can be measured with motor not running).



I am not sure how much manifold pressure is required to cleanly burn all of the fuel delivered by a fully extended guide pin, but I would guess that it is at least around 10 psi. I know that once I get about 3psi of manifold pressure my smoke goes away. This makes me think that the AFC needs to

operate over a wider pressure range. The amount of travel possible for the sliding pin is limited by the flexibility of the diaphragm and the design of the AFC housing. So we can't

just make the pin slide further. However, if we had a steeper angle on the control cone, and a stiffer spring, then a specific pressure would result in less movement of the sliding pin, but the same movement of the "guide pin", and the same fuel delivery for that pressure. Overall, it would allow for a

wider pressure range to have an effect on fuel delivery, with the same travel of the "sliding pin





Bob. . 1st Gen Moderator.

 

[ETOBICOKE]

Thanks!

Thanks for posting the VE pump information, found it very interesting. Did not know that the VE pump governed speed vs throttle position, would account for how easily our trucks hold their speed on grades without changing throttle position. Had always believed that the governor only prevented overspeeding the engine.



Neil

 

[BushWakr - RIP]

Internal view of various pump components...

 

[BushWakr - RIP]

More...

 

[BushWakr - RIP]

One more...

 

[BushWakr - RIP]

Last one for now...

 

[BushWakr - RIP]

Next pic in series. .



Bob.

 

[BushWakr - RIP]

Next pic.

 

[driverswanted]

Bosch-VE

Thought someone would like to see the real thing. Without Aneroid setup.