Land Rover Diesel Distributor Pumps Bosch Bosch Manual

							Sac-hole nozzle with cylindrical sac hole
and conical tip (6b):
This type of nozzle is used exclusively
with spray-hole lengths of 0.6 mm. The
tip’s conical shape enables the wall
thickness to be increased between the
throat radius and the nozzle-body seat
with an attending improvement of nozzle-
tip strength.Sac-hole nozzle with conical sac hole
and conical tip (Fig. 6c):
Due to the conical shape of this nozzle’s
sac hole, its volume is less than that of a
nozzle with cylindrical sac hole. The
volume is between that for a seat-hole
nozzle and a sac-hole nozzle with cylin-
drical sac hole. In order to achieve uni-
form tip-wall thickness, the tip’s conical
design corresponds to that of the sac
hole.
Nozzles 
and nozzle
holders
49
Sac-hole nozzle
1Pressure shaft, 2Needle-lift stop face,
3 Inlet passage, 4Pressure shoulder,
5Needle shaft, 6Nozzle tip,
7Nozzle-body shaft, 8Nozzle-body shoulder,
9Pressure chamber, 10Needle guide,
11Nozzle-body collar, 12Locating hole,
13Sealing surface, 
14 Pressure-pin contact surface.Sac-hole shapes
aCylindrical sac hole with round tip,
bCylindrical sac hole with conical tip,
cConical sac hole with conical tip.
1Shoulder, 2Seat entrance, 3Needle seat, 
4Needle tip, 5Injection orifice, 
6Injection-orifice entrance, 7Sac hole, 
8Throat radius, 9Nozzle-tip cone, 
10Nozzle-body seat, 11Damping cone.
5
6 7 8 9 10 11
4 2
3
1 a
b
c
Fig. 5
UMK1403Y
Fig. 6
UMK1650Y 
						

							Seat-hole nozzle
In order to minimise the residual volume
– and therefore the HC emissions – the
start of the spray hole is located in the
seat taper, and with the nozzle closed it is
covered almost completely by the nozzle
needle. This means that there is no direct
connection between the sac hole and the
combustion chamber (Figs. 7 and 8). The
sac-hole volume here is much lower than
that of the sac-hole nozzle. Compared to
sac-hole nozzles, seat-hole nozzles have
a much lower loading limit and are there-
fore only manufactured as Size P with a
spray-hole length of 1 mm.
For reasons of strength, the nozzle tip is
conically shaped. The spray holes are
always formed using e.c.m. methods. Standard nozzle holders
Assignments and designs
Nozzle holders with hole-type nozzles in
combination with a radial-piston distrib-
utor injection pump are used on DI
engines. 
With regard to the nozzle holders, one
differentiates between 
– Standard nozzle holders (single-
spring nozzle holders) with and with-
out needle-motion sensor, and 
– Two-spring nozzle holders, with and
without needle-motion sensor. 
Application
The nozzle holders described here have
the following characteristics:
– Cylindrical external shape with diame-
ters between 17 and 21 mm,
– Bottom-mounted springs (leads to low
moving masses),
– Pin-located nozzles for direct-injection
engines, and 
– Standardised components (springs,
pressure pin, nozzle-retaining nut)
make combinations an easy matter.
Design
The nozzle-and-holder assembly is com-
posed of the injection nozzle and the
nozzle holder.
The nozzle holder comprises the follow-
ing components (Fig. 9):
– Nozzle-holder body,
– Intermediate element,
– Nozzle-retaining nut,
– Pressure pin,
– Spring,
– Shim, and 
– Locating pins.
The nozzle is centered in the nozzle body
and fastened using the nozzle-retaining
nut. When nozzle body and retaining nut
are screwed together, the intermediate
element is forced up against the sealing
surfaces of nozzle body and retaining
nut. The intermediate element serves as
the needle-lift stop and with its locating
pins centers the nozzle in the nozzle-
holder body. 
Axial-piston
distributor
pumps
50
Seat-hole nozzle
Seat-hole nozzle: Tip shape 
Fig. 7
UMK1408Y UMK1407Y
Fig. 8 
						

							The nozzle-holder body contains the
– Pressure pin,
– Spring, and 
– Shim.
The spring is centered in position by the
pressure pin, whereby the pressure pin is
guided by the nozzle-needle’s pressure
shaft.
The nozzle is connected to the injection
pump’s high-pressure line via the nozzle-
holder feed passage, the intermediate
element, and the nozzle-body feed pas-
sage. If required, an edge-type filter can
be installed in the nozzle holder. 
Method of operation
The nozzle-holder spring applies pres-
sure to the nozzle needle through the
pressure pin. The spring’s initial tension
defines the nozzle’s opening pressure
which can be adjusted using a shim. 
On its way to the nozzle seat, the fuel pas-
ses through the nozzle-holder inlet pas-
sage, the intermediate element, and the
nozzle nody. When injection takes place,
the nozzle needle is lifted by the injection
pressure and fuel is injected through the
injection orifices into the combustion
chamber. Injection terminates as soon as
the injection pressure drops far enough for
the nozzle spring to force the nozzle
needle back onto its seat.
Two-spring nozzle holders
Application
The two-spring nozzle holder is a fur-
ther development of the standard nozzle
holder, and serves to reduce combustion
noise particularly in the idle and part-load
ranges. 
Design
The two-spring nozzle holder features
two springs located one behind the other.
At first, only one of these springs has an
influence on the nozzle needle and as
such defines the initial opening pressure.
The second spring is in contact with a
stop sleeve which limits the needle’s
initial stroke.
Nozzles 
and nozzle
holders
51Standard nozzle holder
1Edge-type filter, 2Inlet passage,
3Pressure pin, 4Intermediate element,
5Nozzle-retaining nut, 6Wall thickness,
7Nozzle, 8Locating pins, 9Spring,
10Shim, 11Leak-fuel passage,
12Leak-fuel connection thread,
13Nozzle-holder body, 14Connection thread,
15Sealing cone.
1
2
3
4
5
6
7 8
9 10 11
12
14
13
15
Fig. 9
UMK1413Y 
						

							When strokes take place in excess of the
initial stroke, the stop sleeve lifts and both
springs have an effect upon the nozzle
needle (Fig. 10).
Method of operation
During the actual injection process, the
nozzle needle first of all opens an initial
amount so that only a small volume of
fuel is injected into the combustion
chamber. 
Along with increasing injection pressure
in the nozzle holder though, the nozzle
needle opens completely and the main
quantity is injected (Fig. 11). This 2-stage
rate-of-discharge curve leads to “softer”
combustion and to a reduction in noise.
Nozzle holders with needle-
motion sensor
Application
The start-of-injection point is an impor-
tant parameter for optimum diesel-engine
operation. For instance, its evaluation
permits load and speed-dependent injec-
tion timing, and/or control of the exhaust-
gas recirculation (EGR) rate. 
Axial-piston
distributor
pumps
52Two-spring nozzle holder for direct-injection
(DI) engines
1Nozzle-holder body, 2Shim,
3Spring 1, 4Pressure pin,
5Guide element, 6Spring 2,
7Pressure pin, 8Spring seat,
9Shim, 10Intermediate element,
11Stop sleeve, 
12Nozzle needle,
13Nozzle-retaining nut, 
14 Nozzle body.
h
1Initial stroke,
h
2Main stroke.1
2
3
4
5
6
7
8
91011
12
13
14
h2
h1
Comparison of needle-lift curves
aStandard nozzle holder (single-spring nozzle
holder),
bTwo-spring nozzle holder.
h
1Initial stroke, h2Main stroke.
0.4 mm
0.2
0
01
Time
Nozzle-needle lift
2 ms
0.4 mm
b a
0.2
0
h2
h1
UMK1423-1Y
Fig. 10
UMK1422E
Fig. 11 
						

							This necessitates a nozzle holder with
needle-motion sensor (Fig. 13) which
outputs a signal as soon as the nozzle
needle opens.
Design
When it moves, the extended pressure
pin enters the current coil. 
The degree to which it enters the coil
(overlap length “X” in Fig. 14) determines
the strength of the magnetic flux.
Method of operation
The magnetic flux in the coil changes as
a result of nozzle-needle movement and
induces a signal voltage which is propor-
tional to the needle’s speed of movement
but not to the distance it has travelled.
This signal is processed directly in an
evaluation circuit (Fig. 12). 
When a given threshold voltage is ex-
ceeded, this serves as the signal to 
the evaluation circuit for the start of 
injection.Nozzles 
and nozzle
holders
53
Needle-motion sensor in a two-spring nozzle
holder for direct-injection (DI) engines
1Adjusting pin, 2Terminal,
3Current coil, 4Pressure pin,
5Spring seat.
X Overlap length.
2 1
X
3
4
5
Two-spring nozzle holder with needle-motion
sensor for direct-injection (DI) engines
1 Nozzle-holder body, 2Needle-motion sensor,
3Spring 1, 4Guide element, 5Spring 2,
6Pressure pin, 7Nozzle-retaining nut.
1
2
3
4
5
6
7
UMK 1588 D
Comparison between a needle-lift curve and
the corresponding signal-voltage curve of the
needle-motion sensor
a
Needle-lift-
sensor signal
Needle-
motion-
sensor signal
Start-of-injection
signal Theshold
voltage
Needle lift Signal voltage
b
¡cks
Fig. 12
UMK1427E
Fig. 14
UMK1529Y
Fig. 13
UMK1588Y 
						

							Mechanical diesel-engine speed control
(mechanical governing) registers a wide
variety of different operating statuses 
and permits high-quality A/F mixture
formation. 
The Electronic Diesel Control (EDC)
takes additional requirements into ac-
count. By applying electronic measure-
ment, highly-flexible electronic data pro-
cessing, and closed control loops with
electric actuators, it is able to process
mechanical influencing variables which it
was impossible to take into account with
the previous purely mechanical control
(governing) system. 
The EDC permits data to be exchanged
with other electronic systems in thevehicle (for instance, traction control
system (
TCS)
, and electronic transmis-
sion-shift control). In other words, it can
be integrated completely into the overall
vehicle system. 
System blocks
The electronic control is divided into
three system blocks (Fig. 1):
1. Sensors for registering operating
conditions. A wide variety of physical
quantities are converted into electrical
signals.
2. Electronic control unit (ECU) with
microprocessors which processes the in-
Axial-piston
distributor
pumps,
VE-EDC
54
Electronic Diesel Control (EDC): System blocks
Needle-motion sensor
Temperature sensors
(
water, air, fuel)
Sensor for
control-collar position
Air-flow sensor
Engine-speed sensor 
Vehicle-speed sensor
Sensors
Setpoint generators
Glow control unit Transducer with
EGR valve Fuel-injection pump
Actuators ECU
Micro -
pro-
cessor
Maps
Start of
injection
Starting
control EGR Engine
shutoff
Injected
fuel quantity
Atmospheric-pressure
sensor
Diagnosis
Diagnosis displayAccelerator-pedal sensor
Speed-selection lever
Electronically-controlled
axial-piston distributor fuel-
injection pumps VE-EDC 
Fig. 1
UMK0467E 
						

							formation in accordance with specific
control algorithms, and outputs corre-
sponding electrical signals.
3. Actuators which convert the ECU’s 
electrical output signals into mechanical
quantities.
Components
Sensors
The positions of the accelerator and the
control collar in the injection pump are
registered by the angle sensors. These
use contacting and non-contacting
methods respectively. Engine speed and
TDC are registered by inductive sensors.
Sensors with high measuring accuracy
and long-term stability are used for pres-
sure and temperature measurements.
The start of injection is registered by a
sensor which is directly integrated in the 
nozzle holder and which detects the start
of injection by sensing the needle move-
ment (Figs. 2 and 3).Electronic control unit (ECU)
The ECU employs digital technology. The
microprocessors with their input and
output interface circuits form the heart 
of the ECU. The circuitry is completed 
by the memory units and devices for 
the conversion of the sensor signals 
into computer-compatible quantities. The
ECU is installed in the passenger com-
partment to protect it from external in-
fluences.
There are a number of different maps
stored in the ECU, and these come into
effect as a function of such parameters
as: Load, engine speed, coolant tem-
perature, air quantity etc. Exacting de-
mands are made upon interference 
immunity. Inputs and outputs are short-
circuit-proof and protected against spu-
rious pulses from the vehicle electrical
system. Protective circuitry and me-
chanical shielding provide a high level 
of EMC (Electro-Magnetic Compatibility)
against outside interference.
Electronic
control for
distributor
pumps
55
Sensor signals 
1 Untreated signal from the needle-motion sensor
(NBF),
2Signal derived from the NBF signal, 
3Untreated signal from the engine-speed signal,
4Signal derived from untreated engine-speed 
signal,
5Evaluated start-of-injection signal.Nozzle-and-holder assembly with
needle-motion sensor (NBF)
1Setting pin, 2Sensor winding, 3Pressure pin,
4Cable, 5Plug.
1
2
3
4
5
3
1
2
4
5
Fig. 2Fig. 3
UMK0466Y
UMK0468Y 
						

							Solenoid actuator for injected- 
fuel quantity control
The solenoid actuator (rotary actuator)
engages with the control collar through 
a shaft (Fig. 4). Similar to the mechani-
cally governed fuel-injection pump, the
cutoff ports are opened or closed de-
pending upon the control collar’s posi-
tion. The injected fuel quantity can be
infinitely varied between zero and 
maximum (e.g., for cold starting). Using
an angle sensor (e.g., potentiometer),
the rotary actuator’s angle of rotation,
and thus the position of the control col-
lar, are reported back to the ECU and
used to determine the injected fuel
quantity as a function of engine speed.
When no voltage is applied to the ac-
tuator, its return springs reduce the in-
jected fuel quantity to zero.Solenoid valve for 
start-of-injection control 
The pump interior pressure is depen-
dent upon pump speed. Similar to the
mechanical timing device, this pressure
is applied to the timing-device piston 
(Fig. 4). This pressure on the timing-
device pressure side is modulated by a
clocked solenoid valve.
With the solenoid valve permanently
opened (pressure reduction), start of 
injection is retarded, and with it fully 
closed (pressure increase), start of in-
jection is advanced. In the intermediate
range, the on/off ratio (the ratio of 
solenoid valve open to solenoid valve
closed) can be infinitely varied by the
ECU.Axial-piston
distributor
pumps,
VE-EDC
56
1
2
3
4
56
Distributor injection pump for electronic diesel control
1Control-collar position sensor, 2Solenoid actuator for the injected fuel quantity, 3Electromagnetic 
shutoff valve, 4Delivery plunger, 5Solenoid valve for start-of-injection timing, 6Control collar.
Fig. 4
UMK0464Y 
						

							Closed control loops (Fig. 5)
Injected fuel quantity
The injected fuel quantity has a decisive
influence upon the vehicle’s starting, 
idling, power output and driveability 
characteristics, as well as upon its par-
ticulate emissions. For this reason, the
corresponding maps for start quantity,
idle, full load, accelerator-pedal charac-
teristic, smoke limitation, and pump 
characteristic, are programmed into the
ECU. The driver inputs his or her re-
quirements regarding torque or engine
speed through the accelerator sensor.
Taking into account the stored map 
data, and the actual input values from 
the sensors, a setpoint is calculated for
the setting of the rotary actuator in the
pump. This rotary actuator is equippedwith a check-back signalling unit and 
ensures that the control collar is cor-
rectly set.
Start of injection
The start of injection has a decisive in-
fluence upon starting, noise, fuel con-
sumption, and exhaust emissions. Start-
of-injection maps programmed into the
ECU take these interdependencies into
account. A closed control loop is used 
to guarantee the high accuracy of the
start-of-injection point. A needle-motion
sensor (NBF) registers the actual start of
injection directly at the nozzle and
compares it with the programmed start 
of injection (Figs. 2 and 3). Deviations
result in a change to the on/off ratio of 
the timing-device solenoid valve, which
continues until deviation reaches zero.Electronic
control for
distributor
pumps
57
Closed control loop of the electronic diesel control (EDC) 
QAir-flow quantity, n
actEngine speed (actual), pAAtmospheric pressure, ssetControl-collar signal 
(setpoint), s
actControl-collar position (actual), sv setTiming-device signal (setpoint), tKFuel temperature, 
t
LIntake-air temperature, tMEngine temperature, ti actStart of injection (actual).
n actualt Fuel
ELAB
On/Off
Cruise
control
Accelerator
pedal
EGR
control
Injected-
fuel-quan-
tity control Start-of-
injection
control
Injection
nozzleStart-
quantity
control
ECU
Engine and vehicleOperator’s
panelAir
Exhaust
emissions
EGR valveM
ti actual
pA
tL
Ql
sv setpoint
sactual
tK
ssetpointVE-
pump
Vehicle
speed
sensor
UMK0465E
Fig. 5 
						

							This clocked solenoid valve is used to
modulate the positioning pressure at the
timing-device piston, and this results in
the dynamic behavior being comparable
to that obtained with the mechanical
start-of-injection timing.
Because during engine overrun (with 
injection suppressed) and engine start-
ing there are either no start-of-injection
signals available, or they are inadequate,
the controller is switched off and an
open-loop-control mode is selected. The
on/off ratio for controlling the solenoid
valve is then taken from a control map in
the ECU.
Exhaust-gas recirculation (EGR)
EGR is applied to reduce the engine’s
toxic emissions. A defined portion of the
exhaust gas is tapped-off and mixed 
with the fresh intake air. The engine’s 
intake-air quantity (which is proportional
to the EGR rate) is measured by an air-
flow sensor and compared in the ECU
with the programmed value for the EGR
map, whereby additional engine and 
injection data for every operating point
are taken into account.
In case of deviation, the ECU modifies
the triggering signal applied to an 
electropneumatic transducer. This then
adjusts the EGR valve to the correct 
EGR rate.
Cruise control
An evaluated vehicle-speed signal is
compared with the setpoint signal input-
ted by the driver at the cruise-control 
panel. The injected fuel quantity is then
adjusted to maintain the speed selected
by the driver.
Supplementary functions
The electronic diesel control (EDC) 
provides for supplementary functions
which considerably improve the ve-
hicle’s driveability compared to the
mechanically governed injection pump.
Active anti-buck damping
With the active anti-buck damping 
(ARD) facility, the vehicle’s unpleasant
longitudinal oscillations can be avoided.
Idle-speed control
The idle-speed control avoids engine
“shake” at idle by metering the appro-
priate amount of fuel to each individual
cylinder.
Safety measures
Self-monitoring
The safety concept comprises the 
ECU’s monitoring of sensors, actuators,
and microprocessors, as well as of the
limp-home and emergency functions 
provided in case a component fails. If
malfunctions occur on important com-
ponents, the diagnostic system not only
warns the driver by means of a lamp in
the instrument panel but also provides a
facility for detailed trouble-shooting in 
the workshop.
Limp-home and emergency 
functions
There are a large number of sophisti-
cated limp-home and emergency func-
tions integrated in the system. For in-
stance if the engine-speed sensor fails, 
a substitute engine-speed signal is 
generated using the interval between 
the start-of-injection signals from the
needle-motion sensor (NBF). And if the
injected-fuel quantity actuator fails, a
separate electrical shutoff device 
(ELAB) switches off the engine. The
warning lamp only lights up if important
sensors fail. The Table below shows the
ECU’s reaction should certain faults 
occur.
Diagnostic output
A diagnostic output can be made by 
means of diagnostic equipment, which
can be used on all Bosch electronic 
automotive systems. By applying a 
special test sequence, it is possible to
systematically check all the sensors 
and their connectors, as well as the
correct functioning of the ECU’s.
Axial-piston
distributor
pumps,
VE-EDC
58