C. MW-Injection Pump With Mechanical Governor (RW)
Operation of Injection Pump and RPM GovernorC. MW-injection pump with mechanical governor (RW)
Layout of injection pump
The layout of the injection pump is essentially the same as that of M-injection pump.
However, the element assembly 11 (12) is mounted to injection 8 pump housing by means of holding flange (11).
Never release fastening nuts of element assembly, because otherwise the basic adjustment of the respective element will be changed and new adjustments on test bench will be required.
Lubrication of injection pump
The injection pump is connected to engine circuit for lubrication. The oil intake (2) for lubrication is at 5th pump element. The oil flows through bores (1) on sealing flange of camshaft back into crankcase.
Relief choke in pipe connection (USA only)
To reduce hydrocarbons in emissions, the pipe connections of the injection pump are provided with relief chokes (orifices). Relief choke (2) is a plate valve (3) with an orifice of 0.6 mm dia., opening in direction of injection nozzle. The valve seat (4) is riveted to pipe connection.
Layout and operation of RW-governor
The governor is an idle speed-maximum speed governor, with its breakaway spring (11) dimensioned and adjusted in such a manner that the governor will not be operative in partial load range, except for adaptation (refer to "governing at start and full load").
In partial load and full load range the control rod (B) of the injection pump is operated from direction of accelerator pedal only, which is connected to adjusting lever (10) of governor via regulating linkage.
At increasing engine speed, the fly weights will move in outward direction as soon as the centrifugal force has become higher than the pressure of the regulating springs. The movement of the fly weights is transmitted to control rod (B) via governor sleeve (5), linkage (13) and regulating lever (7).
The control rod will be displaced in direction of stop as soon as the maximum speed is attained. As a result, the delivered quantity of fuel will become smaller, and the engine speed will be limited. With dropping speed, operation is vice versa.
Governing at start
In rest position, the swivel lever (2) is pushed to the left against stop (17) under influence of breakaway spring (11) and angle lever (1).
In addition, the fly weights (4) are pushed into their starting position completely inwards by means of the idle speed spring (12) via governor sleeve (5).
When the accelerator pedal or the adjusting lever (10) is operated, the control rod (B) can be moved into starting position (a), since the starting fuel lock, comprising cam (9) and sensor finger (8) has been switched off.
As soon as the engine and thereby the camshaft of the injection pump are beginning to rotate, the fly weights (4) will be moving in outward direction while governor sleeve (5) together with linkage (13) are moved to the right against the spring pressure of the idle speed spring (12).
The pin of the governor sleeve is slidingly located in slot of swivel lever (2). The respective movement will be transferred to the control rod by way of the connecting lever (16) and the regulating lever (7). Finger (8) is swivelled out of cam (9) under influence of control rod. If the speed increases, since the engine is starting, the governor sleeve (5) with linkage (13) and control rod (B) are each moving in the same direction, that is, a movement of the governor sleeve to the right causes the control rod to move also to the right. The injected quantity of fuel is reducing, the engine speed is decreasing.
Governing at idle
The adjusting lever (10) rests outside against resilient idle speed stop. (As a result, the idle speed stop can be overcome during manual shutoff.) In this position, the fly weights (4) together with the idle speed spring (12) are establishing a constant idle speed.
If the speed drops, the fly weights (4) are pushed inwards through spring force of idle speed spring (12). The governor sleeve (5) and thereby the linkage (13) will move to the left. The linkage moves the control rod (B) also automatically to the left via connecting lever (16) and regulating lever (7), which means an increase in quantity and thereby an increase in speed.
The fly weights are again moving away from each other. The governor sleeve and thereby the control rod are moved to the right (less injected fuel) until centrifugal force and spring force of idle speed spring (12) are in balance. By this means, an almost constant speed can be maintained even if the air conditioning system, power steering or a driving position are engaged. To stabilize idle speed, the swivel lever (2) is provided with an idle speed auxiliary spring (14, poppet), which pushes against idle speed spring as from a given speed and thereby stabilizes the idle speed.
Full load and breakaway
In partial and full load range the control rod (B) of inspection pump is actuated from direction of accelerator pedal only, which is connected to the adjusting lever (10) of the governor by way of the regulating linkage.
In full load position, the adjusting lever (10) rests outside against full load stop, that is, the control rod is at full load = max. delivered quantity which can be burned free of smoke by engine.
The starting quantity lock, comprising finger (8) and cam (9) prevents merely that no starting fuel is injected during full load and at low speeds.
Breakaway at full load and partial load proceeds at a given max. speed. The centrifugal force of the fly weights (4) will become higher than the preload force of the breakaway spring (11), so that swivel lever (2) will move from housing stop (17) to the right.
The resulting governor sleeve path will lead by way of the various transmission elements to a control rod movement in the direction of stop (0), until a given speed and injection quantity in accordance with engine load have been achieved.
If the engine is relieved with the position of the adjusting lever unchanged, speed will increase under no-load conditions up to max. speed. A speed difference between begin of breakaway and end of breakaway (max. speed unloaded) can be used to determine the P-degree (proportional degree).
Position between idle speed and full-load speed regulation
Except for adaptation, there will be no additional governing in this range.
Adaptation serves the purpose of providing the engine with the respectively correct quantity of injected fuel during each operating point on full load curve.
Prior to adaptation the governor is again in the position as shown in illustration. The fly weights have overcome the idle speed spring (12) and the adaptation spring (6) by way of the governor sleeve (5), 50 that the governor sleeve (5) now rests rigidly against swivel lever (2). If the engine load is increased, the speed will drop; the compensating spring (6) will push the adaptation bolt which rests on governor sleeve (5) in outward direction, and the fly weights will move towards each other. The path made by the compensating spring is restricted by means of a stop on compensating bolt. Under influence of moving sleeve, the control rod will be pushed forward for a given distance (adaptation path) via linkage (13) and regulating lever (7), which will increase the injected quantity of fuel and the torque. The operating range of the adaptation is determined by the preload of the compensating spring in compensating capsule and its rigidity.
Automatic altitude adjusting unit
At increasing altitude above sea level (decreasing atmospheric pressure) the two diaphragm units (12) will expand. As from a given outside pressure (atmospheric pressure) the inner force of the diaphragm unit will become higher than the preload of the altitude adjusting unit-preload spring (11). Pushrod (10) will then move in direction "a". As a result, template (7) is lifted from stop (6) in direction "b" by means of a lever and the lever (3) will move in the direction of "c" (refer to lefthand drawing cutout).
Since the regulating lever (4) is coupled to lever (3) by means of a bolt, the regulating lever (4) and thereby the control rod (9) are moving in direction "d", so that less fuel will be injected. The more the adjusting lever (1) is adjusted in direction of idle (stop) the closer will bolt (5) of lever (3) move toward pivot (8).
As a result, adjustment at partial load is constantly getting lower and will move to almost zero adjustment in idle speed position. At low altitudes above sea level the template (7) constitutes a concentric circle around adjusting lever shaft (2), 50 that behavior of governor will not be corrected.