J'ai trouvé ce qui suit, extrait d'un document BOSCH, qui aide bien à comprendre le "how-it-works" de Syche.
W124 TURBODIESEL BOSCH INJECTION PUMP OM602 AND OM603
J. RSF governor
a) Design and operating principle
The governor is a minimum/maximum speed governor. its governor spring (2m) is sized and set in such a way that it does not govern in the part load range, with the exception of torque control (refer to “Control when starting and at full load") In the part load and full load range, the control rod (2t) of the injection pump is operated only from the accelerator pedal, which is connected through the accelerator control linkage to the control lever (2g) of the governor.
The position spring (2n) is pretensioned and the position speed set by the adjusting screw (3).
2 Governor
2a Guide lever
2b Stop screw for position quantity
2c Relay lever
2d Fulcrum lever
2e Spring retainer (torque control)
2f Full load adjusting screw
2g Control lever
2h Sliding sleeve
2i Flyweights (pump governor group)
2j Position auxiliary spring cutoff
2k Adjusting screw for position auxiliary spring (position stabilizer)
2| Tensioning lever
2m Governor spring
2n Posmon spnng
2o Position auxiliary spring (position stabilizer)
2p Steering arm
2r Stop lever
2s Emergency stop lever
2t Control rod
3 Adjusting screw for position speed
3a Locking nut
6 Vacuum unit (stop)
La vis que j'ai touchée pour l'instant et que j'appelais réglage du débit est (3) "position speed" qui est le seul réglage accessible de l'extérieur.
Pour aller plus loin, je vais relire tout ça encore plusieurs fois. Je ne vois pas de "idle governor" ou "idle spring" sur les éclatés Bosch.
Avant d'ouvrir, je veux être sur d'avoir tout compris.
b) Control positions
Control lever (2g) rests against the idle stop screw (2b). As the engine speed increases, the sliding sleeve (2h) passes through the idle position. Guide lever (2a) swivels around the pivot point ”A” and thus operates against the idle spring (2n).
At a certain engine speed, the guide lever (2a) moves against the adjusting nut of the idle auxiliary spring (20). The movement of the sliding sleeve (2h) is transmitted through the relay lever (20) and fulcrum (2d) in the same direction to the control rod of the injection pump After passing through the idle position, the
sliding sleeve (2h) moves against the spring retainer (2e).
If the engine speed increases further (e.g. deceleration), above a certain engine speed, the spring retainer (2e) is over-compressed followed by the governor spring (2m) . The control rod is thus brought into the "stop position” (deceleration fuel cutoff).
c) Control with actuator
The lift rod (163) rests against the guide lever (2a). The actuator (Y22) is supplied by the electronic idle speed control unit with a clocked D.C. voltage in the frequency range of approx. 50 Hz. If engine speed drops (e.g. drive position engaged or power steering turned to full lock), the actuator is energized with a higher voltage.
This causes the lift rod (163) to press against the guide lever (2a) and the control rod (2t) to move in the direction "a" increased quantity.
As soon as the engine speed increases, the voltage is reduced and the control rod (2t) moves in the direction of “b” reduced quantity.
d) Start position
If the control lever (2g) is moved against the full load stop (c) (fixed stop on governor housing) when the engine is not running, the relay lever (2c) moves around pivot point "B" and moves the fulcrum lever (2d) with it in the direction of Start. When the control lever is in the full load position (2g " Full throttle”) the idle auxiliary
spring (20 idle stabilizer) is pressed away from the guide lever by the idle cutoff auxiliary spring (2j). This enables a more rapid cutoff from the start position of the governor.
e) Full load speed regulation / compensation
After passing through the idle step (c) (refer to ill. of control when at idle) the governor sleeve (2h) moves against the spring retainer (2e). This causes the relay lever (20) and fulcrum lever (2d) to move the control rod of the injection pump into the full load position.
When a certain engine speed is reached, the spring retainer (2e) is over-compressed by a certain distance (d) (compensation).
lf the engine speed continues to rise, the force of the flyweights is sufficient to over-compress the governor spring (2m) (full load speed regulation). The start of cutoff depends on the preload of the governor spring (2m).
f) Engine stop
The vacuum unit (6) is pressurized with vacuum from the vacuum pump through the glow start switch of the vehicle. This causes the diaphragm of the vacuum unit to move against the compression spring.
The vacuum unit (6) is connected to a stop lever (2r), which swivels about the pivot point pulling the control rod of the injection pump into "Stop" position. This causes the deflecting spring of the fulcrum lever to be over-compressed. The control rod can be pulled into the "Stop" position from the outer side of the governor in the same way by means of the emergency stop lever (2s).
K. Intake manifold pressure compensator (ALDA)
The intake manifold pressure compensator (ALDA device) is comprised of a housing (103) with barometer unit (103b). The absolute pressure acts upon the barometer units through a port (103a) to the charge air pipe of the engine. Accordingly, the barometer units react to each pressure change with a change of length.
All movements are transmitted to the compound lever of the governor and to the control rod.
As the absolute pressure drops, the barometer units expand. The correction linkage (1030) of the units is pressed downwards and acts on the compound lever to move the control rod in the direction of "reduced quantity”. As the absolute pressure rises, caused by a higher air and/or charge pressure, the movement is performed in the opposite direction - i.e. in the direction of "increased quantity". As the effect of the ALDA device diminishes, the more the control lever is moved in the idle direction. When the control lever is in the idle position, the effect is approximately zero.
Absolute pressure with charge operation
The intake air under atmospheric pressure is further compressed by the turbocharger.
Atmospheric and charge pressure together produce the absolute pressure prevailing in the charge air pipe of the engine.
a Atmospheric pressure, corresponding to suction quantity
b Charge pressure
c Absolute pressure, corresponding to charge quantity
n Engine speed
p Pressure in bar
The control rod travel sensor is installed in the governor of the injection pump. lt consists of an iron core, two coils (measured value and fixed value coil) and two short-circuit rings. It is connected to the electronic control unit by a 3-pin plug.
The coils (b) and (d) are attached to the iron core (a) which is fixed in the housing. The short-circuit ring (e) is connected to the control rod (2t) and is displaced with the control rod without touching on the bottom leg of the iron core. The fixed value coil (b) and the short-circuit ring (c) are attached to the top leg.
Function
The fixed value coil (b) with the short-circuit ring (c) represents a constant inductance. Depending on the change in position of the control rod (2t), the distance between the short-circuit ring (e) and measuring coil (d) changes. The variable inductance produced is then compared to the constant inductance. From this the electronic unit determines the control rod travel.
Le document Bosch d'où viennent ces extraits est ici : http://www.w124performance.com/service/ ... .1-010.pdf
à bientôt,