BOSCH COMMON RAIL 1st and 2nd Generation
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BOSCH 1 2
Modells: Elantra (XD) Trajet (FO) Santa Fe (SM) Matrix (FC) Engine(s): 1.5 D3EA 2.0 D4EA
BOSCH 2 Modells: Starex (H1) Engine(s): 2.5 D4CB (A-Engine)
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Comparison BOSCH 1
BOSCH 2___________
Electrical pre supply pump (in tank)
Mechanical pre supply pump (part of High pressure pump)
Fuel temperature sensor
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Hot-film air mass meter
MAF-Sensor
Outlet control
Inlet control
High pressure pump driven from camshaft or toothed belt
High pressure pump driven from timing chain
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High pressure pump The main defect of the rotating piston pump is that of the maximum pressure which can be reached. This is fixed at between 200 and 400 bar which, considering that high pressure guarantees rapid transfer, is insufficient to ensure
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the rapid injection of the necessary quantity of fuel for combustion. With the Common Rail it is possible to increase the fuel pressure to 1350 bar thereby increasing the speed at which it can be transferred. This high pressure not only ensures rapid injection but also makes it possible to precede injection With a pre-injection phase thereby anticipating the combustion process with consequent advantages for the Subsequent combustion. The higher the injection pressure, the higher the injection thermodynamic efficiency. This makes the direct diesel engine the most thermodynamically efficient of all the internal combustion Alternatives.
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High pressure pump The high pressure pump is responsible for generating the high Pressure needed for fuel injection, and for ensuring that there is 5 enough (high pressure) fuel available for all operating conditions. The high-pressure pump´s drive shaft is driven from the engine at half engine speed via a toothed belt or direct from the camshaft . It is lubricated and cooled by the fuel that it pumps. The fuel is forced by the pre-supply pump into the high-pressure pump´s inner chamber via a safety valve. When the pump plunger moves downwards, the inlet valve opens and fuel is drawn into the pumping-element chamber (suction stroke). At bottom dead centre (BDC), the inlet valve closes and the fuel in the chamber can be compressed by the upwards moving plunger.
Fuel feed
Pressure Control valve
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High pressure pump Main c ompo nents : ① drive shaft
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② Eccentric cam. ③ Pumping element with pump piston ④ Inlet valve ⑤ Outlet valve
Inlet valve Outlet valve
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High pressure pump 7
Low pressure
TO ACCUMULATOR
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System o verview B OSCH 1
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Outlet contr ol : Located at the end of accumulator line and control the output pressure from H/P pump by increasing or decreasing the total return fuel quantity Bosch version 1. (D Engine) required a fuel temperature sensor to make compensations of fuel delivery (80 ~ 120 C)
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Low pressure circuit In the low pressure circuit the fuel is drawn out of the tank by a pre-supply pump, forcing fuel through the lines to the high pressure circuit. Contaminants are removed from the fuel by a pre-filter thus preventing the premature wear of the high precision components
Pesupply pump
Fuel Filter
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Pre-Supply pump 10
Pump Capacity
Tank Capacity
SM, FO 185 l/h (Ext)
SM, FO 65l (steel)
XD
175 l/h (Int)
XD
55l (plastic)
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High pressure circuit High P ressu re Circu it (1.) Generate and stor e hig h pressure
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The fuel passes through the fuel filter to the high-pressure pump which forces it into the high-pressure accumulator (rail) and generates a pressure of maximum 1,350 bar. For every injection process, fuel is taken from the highpressure accumulator. The pressure in the rail remains constant, a pressure-control vavle is employed to ensure that the pressure in the rail does not exceed a desired value or drop below it.
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High pressure circuit High Pressure C irc uit (2.) Closed- loop con tro l o f rail pressure
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The pressure-control valve is triggered by the ECM. When open, it permits fuel to return to the tank via the return lines and the rail pressure sinks. In order that the ECM can trigger the pressure- control valve correctly, the rail pressure is measured by a rail pressure sensor.
Hig h Pressur e Cir cui t (3.) Fuel Injectio n Every time fuel is injected, it is extracted from the rail at high pressure and injected directly into the cylinder. Each cylinder has its own injector. Each injector contains a solenoid valve which receives its `open´ command from the ECM. As long as it remains open, fuel is injected into the cylinders combustion chamber
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Press ur e co nt ro l v alv e The pressure-control valve is responsible for maintaning the pressure in the rail at a constant level. This level is a function 13 of the engine´s operating status. If the fuel pressure is excessive, the valve opens and the fuel flows back to the tank through a return line. If the pressure is not high enough, the valve closes and the high-pressure pump is able to increase the pressure in the rail.
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Press ur e co nt ro l valv e The valves seat ball is subjected to pressure from the highpressure accumulator. This force is appopsed by the total 14 forces acting against the ball from the other side by the spring and the electromagnet. The force generated is a function of the current with which it is activated. Therefore, a variation in current permits the high-pressure in the accumulator to be set at a given value. The variable current is achieved by using pulse width modulation (PWM)
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1. Rail pressure sensor
2. Fuel rail
3. Pressure control valve
4. Electric connection
5. Evaluation circuit
6. Diaphragm and sensor element
7. 0.7mm hole for the throttle 8. Ball valve 9. Electric connector
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Press ur e co nt ro l valv e
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Opening degree of t he pressur e regul ato r valve 15
(Pulse width modulated control with frequency 1.0 kHz)
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System overview BOSCH 2 16
Inle t con trol : integrated with H/P pump and control the fuel quantity from feed pump to high pressure pump Advantage of inlet control type Minimize the increasing fuel temperature only supplying optimized fuel volume driving torque of High Pressure Pump is decreased by 3~4kg-m Disadvantage Difficult to release excess rail pressure in sudden deceleration condition. Bosch version 2. (A Engine) Fuel temperature reaches approx. 70 C, compensation is not required, therefore, is not fitted with a fuel temperature sensor.
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Low pre ssur e circ uit Featuring an internal gear pump, the CP3.2 high pressure pump draws the fuel from the tank, through the fuel filter, then 17 through a suction throttle to creat an internal pressure of 4.5 ~ 6.0 bar
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Pre sup pl y pum p 18
Description - Maintaining an adequate fuel supply to the high pressure pump - Type : Mechanically driven gear type and integrated in the high pressure pump with which it shares a common drive.271.03ℓ/Feed - Main features : ① Delivered fuel quantity is practically proportional to the engine speed ② Maintenance-free - Suct io n p ress ur e : 0.5 ~ 1 bar
- Feed p res su re : 4.5~6.0 bar - Feed Quantity @ 2798 rpm; 1.03ℓ/min - Max. Pressure Quantity; 80ℓ/hr
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Low pre ssure circ uit Fuel return Connecto r for fuel leve l change
Fuel Tank
Air filter
Above is an example but the same
Starex model, the fuel tank must be removed (shop manuel is incorrect)
Fuel supply
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High pressure pump In case of BOSCH 2 a gear pump was added. 20
MPROP: (Magnetic Proportion Valve) KUV: (Kraftstoffüberdruckventil......Over pressure saftey valve)
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High pressure pump The high pressure pump is a compact unit, mounted to be driven from the timing chain.
Water temp sensor
Fuel inlet
Fuel return (to tank) Fuel outlet (to rail)
Regulator valve (MPROP)
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Regulator Valve (MPROP) A magnetic proportion valve (MPROP) is located directly on the high pressure pump. It regulates the volume of fuel entering into the low pressure circuit under pressure (4.5 ~ 6.0bar) from the gear pump. Controlled by the ECM depending upon driver demands, and prevailing engine conditions. Pressu re-con tr ol valve NO T energ ized the valve is fully open, supply fuel pressure exceeds spring force, opening the valve.
The fuel is used for pump lubrication and supplying the High pressure pump
From feed pump To h/p pump
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Regulator Valve (MPROP) Pressu re-con tr ol v alv e energ ized : When the pressure control valve is energized (ignition on ) it23is opened to approx. 62%. This allows the fuel (under cranking) to enter the high pressure pump. Due to the high frequency a hunning noise may be heard from the MPROP valve, this is normal. Upon recieving the CKP signal (engine start) the valve is then regulated to suit the mapping for the prevailing engine condition. During decleration the valve is moved to the closed position) the fuel from feed pump can not go through the pressure control valve and is returned through the return passage inside of the pump. Lubrication is provided via a small orifice The electromagnet’s forces are proportional to its energizing current which is varied by PWM (pulse-width modulation) pulsing. From feed pump To h/p pump
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Regulator Valve (MPROP) The position of the valve is determined by the ECM depending upon driver demands, the final fuel quanitity is determined by the slots in the piston
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Regulator Valve (MPROP) 25
-Idle (800rpm) : -On duty ≒ 55% -Rail pressure ≒ 270bar
-WOT( no load) condition (4500rpm): -On duty ≒ 65% -Rail pressure ≒ 1350bar
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High pressure accumulator (rail) The high-pressure accumulator (rail) assignments are: -Store fuel
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-Prevent pressure fluctuations (by means of adequate volume)
-The high-pressure accumulator is a forged-steel tube. Depending upon the engine concerened ist internal diameter is approx. 10mm and is between 280 and 600mm long. To prevent pressure fluctuations, as large a volume as possible should be chosen, in other words maximum-possible lenght and diameter. A small volume is prefered for rapid starting, which means that the target for the volume must be: as small as possible, but as large as necessary.
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Pressure Limiter Valve The high pressure accumulator or rail of the A-Engine is fitted with a pressure limiter valve. The pressure limiter has the same function as an overpressure valve. The valve is a mechanical device comprising of the following part;
Housing with external thread for mounting to rail. -A connection to the fuel tank return line -A movable plunger. -A spring
In such cases of overpressure the pressure limiter permits a short-time maximum rail pressure of 1750 bar.
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Rail Pressure Sensor Pressurized fuel acts on the sensors diaphragm, converting the pressure to an electrical signal, which is amplified and sent to 28 the ECM. When the diaphragm shape changes (approx. 1mm at 1500bar) it causes a voltage change across the 5v resistance bridge. This voltage change is in the range of 0..70mV (depending upon pressure) and is amplified by the evaluation circuit to 0.5 .. 4.5V. The precise measurment of rail pressure is imperative for correct system functioning. Sensor failure: `D´Engine, Limp home mode `A´Engine ECM shuts the engine OFF
In such cases of overpressure and rail pressure sensor records 1480 bar, the ECM will shut down engine.
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Rail Pressure Sensor Specification Ignition ON = Approx. 0.5V Cranking
= 0.5V and increasing
Idle
= Approx. 1. V
Max RPM
= Voltage inceases
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with inceasing pressure. 4.5 V
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2 3
1Electrical connections 4
2Evaluation circuit 3Diaphragm with sensor element 4High-pressure connection 5Mounting thread
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Injector It is the injectors job to inject into the combustion chamber exactly the correct amount of fuel at precisely the right time. 30 To do so, the injector is triggered by signals from the ECM. The injector has an electromagnetic servo-valve. It is a high-precision component which has been manufactured to extremely tight tolerances. The valve, the nozzle, and the electromagnet are located in the injector body. Fuel flows from the high-pressure connection though an input throttle into the valve control chamber. There is the same pressure inside the injector as there is in the rail, and the fuel is injected through the nozzle into the combustion chamber. Excess fuel flows back to the tank through the return line. Maximum & fuel cut off on overrun is RPM acheived by controlling Injectors, via ECM
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Injector (closed – at rest status) Solonoid not energized. Spring pressure forces the armature and valve ball closed. High pressure at valve control chamber and injector nozzle is the same, valve control plunger can´t move..No injection
Fuel return (tank)
Triger element soloniod valve High pressure fuel supply from rail Valve ball Bleed orific Feed orifice Valve control chamber Valve control plunger Feed passage to the nozzle Nozzle needle
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Injector (Opened - injection) The solonoid is energized, allowing the armature and ball valve to lift, opening the bleed orifice, pressure in the valve control32 chamber drops. Rail pressure acting against the valve control plunger causes it to lift allowing injection to take place
Solenoid energized from ECM
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Injector (closed – end of injection) As soon as the solenoid valve is no longer energized, the valve spring forces the armature downwards and the valve ball closes the bleed orifice. Closing the bleed orifice leads to pressure buildup in the control chamber. Consequently this pressure buildup makes pressure balance between in the valve control chamber and in the nozzle chamber and the nozzle needle closes. A = Cont ro l curr ent B = Stroke in mm C = High p ressur e D = Injecti on r ate
a = Control current for solenoid coil b = Valve li ft stro ke c1 = Pressure in the con trol chamber c2 = P. in the needle li ft chamber d = Injection
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Injector (Capacitor) The capacitor is an internal component of ECM 34
18~20A
10~12A
Injector
50%
45%
1= Capacitor discharge
2 = Injector pull in current
3 = Capacitor charge
4 = Injector holding current
5 = Capacitor charge (PST off) 6 = Regulated holding current (free-wheeling) 7 = Regulated holding current (power stage on)
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Injection 35
1 = Pre-injection
1a = Combustion pressure with pre-injection
2 = Main injection 2a = Combustion pressure without pre-injection
Pre-injection Advantages A steady rise in pressure, reducing; the combustion noise, HC emissions, and fuel consumption
Conditions Idling and operation under partial load
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Injection Aim of pre-injection: Reduction in :
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- Combustion noise - HC Emissions - Fuel consumption (late injection start) -Consequence s of pre- injectio n Pre-conditioning of the combustion space for the main injection process both in terms of pressure and temperature. -Ignition delay for main injection is shortned - Noise advantages (reduced peak combustion pressure) - Optimum combustion Consequence s of p ost -injection -Reduction in NOX-emisissions -A certain amount of fuel is injected during the ejection cycle -Slightly increased consumption Activation possibilities Pre-injection: from 90° before TDC to 10° after TDC Main-injection: from 20° before TDC to 10° after TDC Post-injection: from TDC to 200° after TDC
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Secondary Injection With certain versions of Nox catalyic converter, secondary injection can be applied for Nox combustion (reduction). It follows the main injection process and is timed to occur
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during the exhaust stroke, up to 200 ATDC. °
Secondary injection HMC DOES NOT USE THIS IN D, A, & J-3 ENGINES introduces a metered quantity of fuel to the exhaus gas. The injected fuel does not combust but instead vaporises due to he residual heat in the exhaust. The resulting mixture is fored out into the exahust system Part of the fuel will be returned for combustion via the EGR, and has the same effect as an early pilot injection. There is also a risk of bore wash.
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Injector Removal BOSCH 1 Injector 38
Closing plug
T40 Torx (torque: 2.7 0.2 kg m )
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Injector Removal BOSCH 1 Before re-installing injector, clean cylinder head bore and sealing surface. 1) insert brush. 2) clean sealing surface and blow out. Installing 1) Insert new copper sealing ring (if necessary, apply small quantity of grease to bond it to injector). 2) Insert injector (do not touch the nozzle tip) and sliding clamp with clamp bolt. 3) Fit Injector pipe (Nuts finger tight only) 3) Injector clamp bolt (torque: 2.7 0.2 kg m) * If injector too loose, cylinder may loose pressure, * If Injector too tight, may result in pinching of the needle, resulting in knocking or misfire. 4) Install high-pressure pipes.(torque : 1.8-2.3 kgm) * high -pressur e pipes must be inst alled withou t tension 5) Attach return leak rail. Never fit without clip. 6) Check installation by tugging it. 7) Attach elec. Connector. 8) Re-connect battery minus terminal. 9) Start engine and check high pressure circuit for leaks. Read out fault memory and cancel any faults
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ATTENTION 40
Never release high pressure pipes with running engine (Ex.When locating misfiring cylinder) High pressure can be checked only via the Rail Pressure Sensor Voltage Reading. Injector / Cylinder operation can be checked by disconnecting eletrical connector (One by one) Note: Erase any DTC afterwards
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ECM Main function : To control the injection pressure to the engine’s requirements which are calculated according to engine speed and load. •Engine speed and load are high : The degree of turbulence in combustion chamber is very great so the highly pressurized fuel has to optimize combustion. •Engine speed and load are low : If injection pressure is too high in low load stage, the nozzle’s penetration will be excessive and part of the fuel will be sprayed directly onto the cylinder wall, causing the formation of smoke and unburned hydrocarbons. - Pressure control process : Measure the current rail pressure by rail pressure sensor Signal to ECM Calculate the adequate fuel demand by engine speed and load. Control the PCV / MPROP to reach the required value by PWM (Pulse-width modulation)
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Control of Injection process The ECM outputs all the necessary commands in order to: - Keep the pressure in the high-pressure accumulator (rail)
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constant - Start and terminate the actual injection process. The ECM uses the measured values from the sensors (e.g. engine speed, accelerator-pedal position, air temperature) to calculate the correct injection fuel quantity and the optimum start of injection. So-called maps stored in the ECM contain the appropriate injection data for evey measured value. This means that it is possible to implement both pilot and post injection.
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ECM and sensors INPUT
BOSCH1 / BOSCH 2 43
1. Air Flow Sensor (Hot FilmType), MAF -Sensor 2. ECT Sensor 3. CMP Sensor 4. CKP Sensor 5. Rail Pressure Sensor 6. Accel. Pedal Sensor 7. S/W INPUT (IG., Brake, Clutch, Blower Fan, A/CON, A/CON Pressure) 8. Vehicle Speed Sensor In case of BOSCH1 additional signal from 9. Fuel Temp. Sensor
ECM OUTPUT 1. Injector 2. Rail Press. Regulator Valve 3. Main Relay 4. Auxiliary Cabin Heater Relay 5. Glow Plug Relay 6. VAC. Modulator for EGR 7. TH/VLV VAC. Modulator (SM EC/2WD ONLY) 8. CAN(A/T ONLY) 9. Eng. Rpm signal to Tacho. 10. Fuel consumption signal to TRIP Computer
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Hot-film air-mass meter (BOSCH 1) During dynamic operation precise compliance with the correct A/F ratio is imperative in order to comply with the law44 regarding exhaust gas limits. This requires the use of sensors to precisely reguster the airmass flow actually being drawn into the engine at any particular moment. This sensors measuring accuracy must be independant of pulsation, reverse flow, EGR, variable camshaft control and changes in the air temperature control.
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Hot-film air-mass meter (BOSCH 1) A hot-film air-mass meter was selected as being the most suitable. The hot-film principle is based on the transfer of heat 45 from a heated sensor element to the air-mass flow. A micromechanical measuring system is utilised which permits registration of air-mass flow and detection of the flow direction. Reverse flows are also detected in case of strongly pulsating air-flow. The micromechanical sensor element is located in the sensors flow passage
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Mass Air Flow Sensor (BOSCH 2) The hot-film sensor principle is based on the transfer of heat from a heated sensor element to the air mass flow. 46 Unlike that of gasoline engine, diesel engine’s air flow sensor is mainly used to comply with the exhaust-gas limits, EGR (Exhaust Gas Recalculation). Intake air temperature sensor is integrated. - Functions : ① EGR feed back control ② Fuel correction in sudden acceleration or deceleration
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Exhaust Gas Return BOSCH 1 EGR (Exh aust Gas Retu rn ) OFF Con dit ion
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Less than 650 RPM Pressure sensormalfunction malfunction Air flow sensor EGR malfunction Battery below 9V Injection Quantity over 42 mm³ Engine over 3050 RPM Overrun (trailing throttle) over 2000 RPM Idle condition (below 1000RPM for 52 sec s) ´
ON
Coolant OFF
OFF 20
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100
105
(Slight differences between models)
Atmospheric pressure (high altitude) 920 mbar OFF ECM shuts OFF EGR Over 930 mbar ON
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Fuel Filter The fuel filter is located behind the coolant reservoir and the brake master cylinder, (photo was taken with reservior removed). Fuel is drawn from the fuel tank by the low pressure pump, passing through the filter before entering the high pressure pump.
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Fuel Filter Heater The fuel filter heater element is located between the filter head and filter element.
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The incoming fuel flows through the heater element Using the signal from the thermo sensor, the heater is switched ON. ON –3 ± 3°C
OFF. 5 ± 3°C
Pressure Relief valve Thermo switch
OUT
Heater element Connector
IN
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Fuel Filter Heater Comprises of a plastic housing in which two metal contact disc´s are held apart by 4 semi conductors Finally a spring plate is applying pressure to maintain the contact. As current is supplied the semi conductors begin to heat up, therefore heating the diesel fuel passing over them.
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Fuel Temperature Sensor BOSCH 1 Only The fuel temperature sensor is located in the fuel feed line. As the fuel temperature increases, the ECM will modify the injection and delivery rate, at the same time will adjust the parameters of operation of the rail pressure control valve
Fuel Temperature Sensor
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Accelerator Pedal Module / Sensor In contrast to conventional distributor and in-line injection pumps, with EDC (Electronic diesel control) the drivers acceleration input is no longer transmitted to the injection pump by Bowden cable or mechanical linkage, but is
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registered by an sensor and transmitted to the ECM. (this is accelerator-pedal also known as drive by wire) A voltage is generated accross the potentiometer in the accelerator-pedal sensor as a function of the acceleratorpedal setting. Using a programmed characteristic curve, the pedals postion is then calculated from this voltage.
Module Assembly
Sensor Assembly
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Accelerator Pedal Module / Sensor (Pedal + sensor)
APM (Module, pedal/sensor, 1 unit)
XD, FO, SM. RHD/LHD
LC, FC, SM. LHD
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The pedal sensor has two Potentiometers, one signal is the pedal position request signal.to the ECM, the other is for plausabilty of load Should the pedal sensor fail, a limp home mode is set. A slightly higher idle speed. Do not test the Pedal sensor with an Analogue Multi Meter (Risk of damage to the internal circuit. Values Potentiometer 1.
Potentiometer 2.
IDLE
0.6 ~ 0.9V
0.25 ~ 0.6V
WOT
3.6 ~ 4.6V
1.6 ~ 2.5V
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Accelerator Pedal Module / Sensor SANTA - FE 54
Accelerator pedal Module
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Brake switch The brake switch has two circuits; A. Brake light circuit
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A. Cruise control cancellation
B. Redund ant br ake The redundant brake circuit is actuated when the Accelerator Is pressed and then the brake pedal depressed. The ECM will apply a fail-safe mode limiting the signal from Accelerator and controlling the injector operation (fast idle mode) allowing engine to rev to 1200 RPM only When brake is released, APS signal is returned and injector operation re-instated. This operation is a smooth transition without jerking.
NOTE. This only applies when the vehicle is moving (VSS) For carrying out stall test on A/T normal procedures apply.
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Clutch switch The clutch switch has the following functions. 56
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Cancellation of cruise control
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Impending engine load signal (de-clutch, engage first gear, move off)
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To prevent engine RPM surging when de-clutching during gear changes, ECM adjusts injector operation.
Acc
Clutch
RPM
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SPECIAL ATTENTION 57
XD Elantra Intercooler location (front left) Do not install front fog lamps, danger of restricting the air flow to the intercooler
Oil filter, cartridge type. Tightening torque 27Nm Air-venting screw
COMMON RAIL
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Boost-pressure actuator
Passenger car engines with exhaust gas turbocharging must develop high torques even at low engine speeds. The turbochaerger housing 58 is therefore designed for a low exhaust-gas mass flow. But in order that the excessive charge-air pressure is not developed when larger exhaust-gas masses partvalve of this(waste must be diverted past the turbine by means of flow, a bypass gate) into the exhaust system. To do so the boost pressure actuator changes the cross section at the waste gate as a function of engine speed and injected fuel quanitity etc.
1 Boost-pressure sensor 2 Vacuum pump 3 Pressure actuator 5 Waste gate
4 Exhaust-gas turbocharger
COMMON RAIL
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ELANTRA (XD) 59
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COMMON RAIL ELANTRA (XD)
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Intercooler location (front left)
EGR Solenoid Glow relay (Engine) Glow relay (Heater) Oil Filter
EGR Valve
Fuel Filter Location Filter has a fuel temperature sensor and a heating element
