Denso-Common Rail System – Oil level/temperature sensor

fig 1 30 Denso Common Rail System   Oil level/temperature sensor

1 Oil level/temperature sensor
2 Openings
3 Oil dipstick

The 135 PS version of the 2.4l Duratorq-TDCi in the Transit 2006.5 (at the time of going to press) is equipped with an oil level/temperature sensor.

The quality of the engine oil is calculated using this sensor and a strategy implemented in the PCM. This measure is also able to increase the oil change intervals in this version.

Furthermore, the driver receives an indication via the driver information system when the engine oil level has dropped below the limit.

fig 1 31 Denso Common Rail System   Oil level/temperature sensor

1 Electrical connector
2 Wire loop
3 Temperature sensor (NTC)
4 Oil level/temperature sensor

The oil level/temperature sensor comprises a wire loop, which is immersed in the engine oil to a greater or lesser extent corresponding to the oil level. At the time of the oil level measurement, a regulator circuit in the PCM closes the circuit of the wire loop. The regulator circuit regulates a constant current flow of 195 mA through the wire loop. The constant current flow heats the wire loop in a specific way.

The voltage drop (U0) across the wire loop is measured immediately after the circuit closes. Another measurement (U1) takes place approximately 1.75 seconds later.

Between the first measurement (U0) and the second measurement (U1) there is a temperature drop at the wire loop. It is dependent on the extent to which the wire loop is immersed in the engine oil.

The temperature drop results from the dissipation of heat from the wire loop to the engine oil. This temperature drop causes a change in resistance of the wire loop and thus also a change in the voltage drop. The voltage drop is used by the PCM as an indicator for calculating the oil level and the oil quality.

The integral temperature sensor measures the current engine oil temperature and is used as a correction factor for the oil level calculation.

Prerequisites for the measurement

Two conditions must be satisfied in order to ensure the measurement is correct:
• The engine must be stopped for a certain period of time (the planned period is up to two minutes – detailed information was not available at the time of going to press). This provides an adequate return flow of engine oil into the oil pan. In this time, the power supply of the PCM is maintained (Power Latch Phase).
• The vehicle must be standing on a horizontal surface. After completing the second measurement, the PCM calculates the oil level. The calculated value is stored.

Strategy for determining a horizontal surface

fig 1 32 Denso Common Rail System   Oil level/temperature sensor

Vref Reference voltage S Signal to the GEM
1 Instrument cluster
2 PCM
3 GEM
4 Fuel pump and level indicator module

In order to ensure a correct measurement of the oil level, the strategy of the PCM must be certain that the vehicle is standing on a horizontal surface. It assumes that the pump area of a filling station has this type of surface. For this purpose, the signal from the fuel pump and level indicator module is used. If, following “ignition ON”, the fuel level is significantly higher than at the last “ignition OFF”, the PCM assumes that the vehicle is at a filling station and, therefore, is standing on a level surface. The last oil level measurement, that was stored at the last “ignition OFF”, is classified as a valid measurement.

Only this oil level measurement is used for the calculation.

Registering an oil level that is too low

If the PCM has detected refilling of the vehicle fuel tank, the last oil level measurement is compared with the map data. If the measured values indicate an oil level which is too low, a corresponding indicator/text message is displayed on the message center. The indicator/text message illuminates/appears immediately after “ignition ON” and remains active until the next “ignition OFF”. For the next “ignition ON” the lamp/text message is then no longer active.

Note: Even if the engine oil has not been topped up, the indicator/text message is not active again.

Calculation of the oil quality

A strategy is implemented in the PCM that calculates the optimal time for an oil change. This calculation is based on the continuous detection of the engine operating conditions as well as the last valid oil level measurement. If this data reveals an oil change is necessary, then this is indicated via an indicator/text message in the instrument cluster.

Note: After every oil change, the parameters for the oil quality calculation must be reset

04. September 2018 by sam
Categories: Denso-Common Rail System | Leave a comment

Denso-Common Rail System – APP sensor

For safety reasons, the APP sensor is designed as a breakerless double sensor.

fig 1 29 Denso Common Rail System   APP sensor

1 PCM
2 Gateway (GEM)
3 APP sensor

In this system, the signal from APP sensor 1 is transmitted directly as a Pulse Width Modulation signal to the PCM.

The APP sensor 2 signal is transmitted as an analog signal to the GEM.

In the GEM the APP 2 signal is digitized, then put onto the CAN data bus and transferred to the PCM.

Effects of faults

If APP sensor 2 fails, the engine runs with decreased acceleration. However, it is still possible to achieve top speed.

If APP sensor 1 or the entire APP sensor system fails, the engine is regulated to an increased idling speed after the BPP switch and the stoplamp switch have been actuated once and a plausibility check has been carried out. It is possible to continue driving but with greatly reduced power output.

03. September 2018 by sam
Categories: Denso-Common Rail System | Leave a comment

Denso-Common Rail System – MAF sensor

fig 1 28 Denso Common Rail System   MAF sensor

The MAF sensor works according to the hot film principle.

The sensor’s output signal is a digital square-wave signal with a variable frequency.

The following generally applies: the frequency drops with increasing engine speed.

The MAF sensor is used to control the exhaust gas recirculation (closed-loop control).

Effects of faults

In the event of a fault, the EGR system is switched off.

Diagnosis

The monitoring system checks:
• if the values output by the sensor are within the limits,
• the sensor for short circuit to battery/ground,
• for intermittent faults.

Emissions-related component:
• Yes (MIL-active).

03. September 2018 by sam
Categories: Denso-Common Rail System | Leave a comment

Denso-Common Rail System

fig 1 27 Denso Common Rail System

1 CHT sensor
2 MAPT sensor
3 MAF sensor
4 APP sensor
5 Oil level/temperature sensor (certain versions only)
6 Stoplamp switch
7 CKP sensor
8 CMP sensor
9 Fuel pressure sensor
10 VSS (vehicles with no ABS)
11 Oil pressure switch
12 Water-in-fuel sensor (certain markets only)
13 GEM
14 Electric EGR valve with position sensor
15 Ignition lock
16 High pressure pump (with fuel metering valve and fuel temperature sensor)
17 PCM (BARO sensor integrated into the control unit)
18 CAN
19 DLC
20 Electrical turbocharger guide vane adjustment actuator (certain versions only)
21 Fuel injectors
22 Sheathed-type glow plugs
23 Cooling fan module
24 Cooling fan
25 A/C cut-off relay (WAC)
26 A/C compressor clutch

The following components originate from the Denso company:
• High pressure pump (with fuel metering valve and fuel temperature sensor),
• Fuel rail (with fuel pressure sensor and pressure limiting valve),
• Fuel injectors.

The engine management is performed by a Visteon PCM.

03. September 2018 by sam
Categories: Denso-Common Rail System | Leave a comment

Siemens-Common Rail System – Operating principle of the fuel injectors

Fuel injector closed

fig 1 25 Siemens Common Rail System – Operating principle of the fuel injectors

1 High pressure feed line
2 Control piston
3 Fuel return
4 Piezo actuator
5 Valve mushroom
6 Control chamber
7 Nozzle prechamber
8 Injector needle

The fuel is fed at high pressure from the fuel rail via the high pressure feed line into the control chamber and the nozzle prechamber.

The piezo actuator is de-energized and the orifice for fuel return is closed by means of the spring-loaded mushroom valve.

The hydraulic force now exerted onto the fuel injector needle by the high fuel pressure in the control chamber via the control piston is greater than the hydraulic force acting on the fuel injector needle, as the surface of the control piston in the control chamber is greater than the surface of the fuel injector needle in the nozzle prechamber.

The needle of the fuel injector is closed (no injection).

Fuel injector opens

fig 1 26 Siemens Common Rail System – Operating principle of the fuel injectors

1 High pressure feed line
2 Control piston
3 Fuel return
4 Piezo actuator
5 Valve mushroom
6 Control chamber
7 Nozzle prechamber
8 Injector needle
9 Valve piston

The piezo actuator, which is energized by the PCM, expands (charging phase) and pushes against the fuel injector piston.

The mushroom valve opens the orifice which connects the control chamber with the fuel return line.

This results in a pressure drop in the control chamber and the hydraulic force acting on the fuel injector needle is now greater than the force acting on the control piston in the control chamber.

This causes the fuel injector needle to be moved upwards, the fuel injector opens and the fuel enters the combustion chamber via the spray holes.

At a certain point, the piezo actuator is deactivated by the PCM. The fuel injector piston moves back upwards and the mushroom valve closes off the control chamber. As soon as the pressure in the control chamber exceeds the pressure in the nozzle prechamber, the fuel injector needle closes off the spray holes and injection ends.

03. September 2018 by sam
Categories: Siemens-Common Rail System | Leave a comment

Siemens-Common Rail System – Fuel injectors

fig 1 24 Siemens Common Rail System – Fuel injectors

A Fuel injector (1.4L Duratorq-TDCi (DV) diesel engine and 1.8L Duratorq-TDCi (Kent) diesel engine)
B Fuel injector (2.0L Duratorq-TDCi (DW) diesel engine)
C Fuel injector head
D Hydraulic servo system
E Fuel injector nozzle
1 Connector for PCM
2 Piezo actuator
3 High pressure fuel line connection
4 Copper sealing ring
5 Emission standard coding
6 Fuel return port
7 Retainer
8 Fuel return adapter
9 O-ring seal
10 Adapter fastening clip
11 Plastic bush

Depending on the engine version, fuel injectors of different designs are used. Their basic construction and function are however largely the same.

The start of injection and the injection quantity specified by the PCM are implemented by means of the piezo-electrically controlled fuel injectors.

Depending on engine speed and engine load, the fuel injectors are actuated by the PCM with an opening voltage of approximately 70 V. The piezo effect causes the voltage within the piezo element to rise to approximately 140 V.

The fuel injectors inject the appropriate fuel quantity for all engine operating conditions into the combustion chambers in accordance with the combustion cycle.

Extremely short switching times of approximately 200 μs permit extremely rapid reaction to changes in the operating conditions. The fuel quantity to be injected can thus be metered very precisely.

The fuel injectors are divided into three assemblies:
• fuel injector head, including the piezo actuator,
• hydraulic servo system,
• fuel injector nozzle.

NOTE: In the case of repairs, the fuel injectors cannot be dismantled, as this results in their destruction.

NOTE: The wiring harness connectors of the piezo fuel injectors must on no account be detached when the engine is running. The piezo actuators remain expanded for a certain period after the power is interrupted, i.e.
the fuel injectors remain open. Effect: Continuous injection and engine damage!

The copper sealing rings must be replaced during servicing.

Special features

1.4L Duratorq-TDCi (DV) diesel engine:
• In newer versions, a distinction is made between Emission Standard III and Emission Standard IV fuel injectors. A code is stamped onto the fuel injector shaft for this purpose:
– E3 = Emission Standard III,
– E4 = Emission Standard IV.

2.0L Duratorq-TDCi (DW) diesel engine:
• A guide bushing located in the lower part of the cylinder head and a plastic bushing on the fuel injector shaft serve to fasten the fuel injector.

03. September 2018 by sam
Categories: Siemens-Common Rail System | Leave a comment

Siemens-Common Rail System – Fuel rail (common rail) and high pressure fuel lines

The illustration shows the system in the 2.0L Duratorq-TDCi (DW) diesel engine

fig 1 23 Siemens Common Rail System – Fuel rail (common rail) and high pressure fuel lines

1 High pressure fuel lines (to the fuel injectors)
2 High pressure pump line (to high pressure pump)
3 Fuel rail
4 Fuel pressure sensor

The fuel rail is made of forged steel.
The fuel rail performs the following functions:
• stores fuel under high pressure and
• minimizes pressure fluctuations.

Pressure fluctuations are induced in the high pressure fuel system due to the operating movements of the high pressure chambers in the high pressure pump and the opening and closing of the fuel injectors.

The fuel rail is therefore designed in such a way that its volume is sufficient, on the one hand, to minimize pressure fluctuations. On the other hand, the volume in the fuel rail is small enough to build up the required fuel pressure for a quick start in the shortest possible time.

The fuel supplied by the high pressure pump flows via a high pressure line to the fuel rail (high pressure accumulator). The fuel is then delivered to the individual fuel injectors via the four injector tubes which are all the same length.

When fuel is taken from the fuel rail for an injection process, the pressure in the fuel rail is kept almost constant.

Fuel pressure sensor

NOTE: The fuel pressure sensor must not be removed from the fuel rail during servicing. If the fuel pressure sensor is faulty the fuel rail must be replaced along with the fuel pressure sensor.

In order that the engine management system can determine the injected fuel quantity precisely, as a function of current fuel pressure in the fuel rail, a fuel pressure sensor is located on the fuel rail.

High pressure fuel lines

NOTE: The bending radii are exactly matched to the system and must not be changed.

NOTE: After disconnecting one or more high pressure fuel lines, these must always be replaced. Reason: The reason for this is that leaks can occur when re-tightening, due to distortion of the connections of the old lines. The high-pressure fuel lines connect the high-pressure pump to the fuel rail and the fuel rail to the individual fuel injectors.

03. September 2018 by sam
Categories: Siemens-Common Rail System | Leave a comment

Siemens-Common Rail System – Principle of high pressure generation (delivery stroke)

When the pump plunger passes BDC, the inlet valve closes due to the increasing pressure in the high pressure chamber. The fuel in the high-pressure chamber can no longer escape.

As soon as the pressure in the high pressure chamber exceeds the pressure in the high pressure channel, the outlet valve opens and the fuel is forced into the high pressure channel (delivery stroke).

The pump plunger delivers fuel until TDC is reached. The pressure then drops and the outlet valve closes. The pressure on the remaining fuel is reduced. The pump plunger moves downwards.

If the pressure in the high-pressure chamber falls below the transfer pressure, the inlet valve reopens and the process starts again.

03. September 2018 by sam
Categories: Siemens-Common Rail System | Leave a comment

Siemens-Common Rail System – Principle of high pressure generation (intake stroke)

fig 1 22 Siemens Common Rail System – Principle of high pressure generation (intake stroke)

A Fuel intake
B Fuel delivery
C Fuel feed from fuel metering valve
D Fuel delivery to high pressure ring line
1 Inlet valve
2 Outlet valve
3 Piston
4 Drive shaft
5 Eccentric

The three pump plungers are actuated by the rotary movement of the high pressure pump drive shaft and the eccentric on the shaft. When the fuel metering valve opens the inlet to the high pressure chambers, the pressurized fuel from the transfer pump is fed to the inlet valves at the high pressure chambers. If the transfer pressure exceeds the internal pressure of the high pressure chamber (pump plunger in TDC position), the inlet valve opens. Fuel is now forced into the high-pressure chamber, which moves the pump plunger downwards (intake stroke).

03. September 2018 by sam
Categories: Siemens-Common Rail System | Leave a comment

Siemens-Common Rail System – High pressure generation and fuel routing in the high pressure pump

fig 1 21 Siemens Common Rail System – High pressure generation and fuel routing in the high pressure pump

A Fuel feed
B Fuel feed (fuel quantity fed to the high pressure pump)
C High pressure connection to the fuel rail
D Fuel return
1 Admission-pressure control valve
2 Screen filter
3 Intake side of transfer pump
4 Transfer pump
5 Fuel metering valve
6 Fuel pressure control valve
7 Fluid filter
8 High pressure pump
9 Eccentric on drive shaft
10 Pump element inlet valve
11 Pump element outlet valve
12 High-pressure ring line
13 High pressure pump elements
14 Lubrication valve

The fuel is drawn from the fuel tank via the fuel filter by means of the transfer pump integrated in the high pressure pump. The transfer pump delivers the fuel on to the fuel metering valve and to the lubrication valve. When the fuel metering valve is closed, the admission pressure control valve opens and routes the excess fuel back to the inlet side of the transfer pump. The lubrication valve is calibrated in order to always ensure sufficient lubrication and cooling in the interior of the pump.

The fuel quantity fed to the high pressure chambers (pump elements) is determined via the electromagnetically operated fuel metering valve (actuated by the PCM). The fuel pressure control valve is located in the high pressure channel, between the high pressure chambers and the high pressure outlet port to the fuel rail. This electro-magnetically operated valve, which is actuated by the PCM controls the fuel pressure which is fed into the fuel rail via the high pressure outlet port. The fuel pressure control valve routes the excess fuel into the fuel return line and back to the fuel tank.

03. September 2018 by sam
Categories: Siemens-Common Rail System | Leave a comment

← Older posts

Newer posts →

You might also likeclose