Working speed control, function

W07.16-1059-79

General

The electronic working speed control takes place as soon as a power take-off is switched in. To do this up to three power take-offs can be parameterized differently according to the vehicle equipment. This means that different regulation specifications can be set for each power take-off. Depending on the vehicle's area of operation and depending on how the parameters are set for the power take-off functions in the sensor and actuator module, cab (SCA) control unit (A7) or the parameterizable special module (PSM) control unit (A22).

Along with numerous other parameters, it is possible, for example, to set entry requirements such as "parking brake applied," or "transmission in neutral position," or the engine speed range (min. engine speed, max. engine speed), as well as a torque limitation.

During operation of a power take-off, it is also possible to adjust the working speed individually to a working speed between 550 rpm and 750 rpm via the accelerator pedal or the buttons on the multifunction steering wheel, or to raise it to a parameterized value via the idle speed switch (S900).

Control of the working speed

When a power take-off is switched on, its parameters for working speed control are transmitted by the sensor and actuator module, cab (SCA) control unit (A7) and the parameterizable special module (PSM) control unit (A22) via the CAN data bus system to the drive control (CPC) control unit (A3).

The drive control control unit (CPC) (A3) forwards the parameters via the drive CAN (CAN 4) to the engine management control unit (MCM) (A4). Initially, it takes into account only the parameters set in the parameterizable special module (PSM) control unit (A22), as these overlay the parameters set in the sensor and actuator module, cab (SCA) control unit (A7).

In other words: In vehicles with code (E3Y) PSM, body and trailer CAN, ISO 11992 and in vehicles with code (E3Z) PSM, body CAN, ISO 11898 instead of 11992, only the parameters in the parameterizable special module (PSM) control unit (A22) are taken into account, regardless of which parameters are set in the sensor and actuator module, cab (SCA) control unit (A7).

Upon reception of the respective information and while taking account of the current operating condition of the engine, engine management (MCM) control unit (A4) calculates the required actuation begin of the fuel injectors as well as the necessary actuation period (injection quantity). By actuating the quantity control valve (Y642) and the fuel injectors of

cylinders 1 to 6 (Y608 to Y613), it causes the right amount of fuel to be injected into the corresponding combustion chamber at the right time.

 The working speed is only regulated if the appropriate power take-off is fully engaged.

Changing the working speed

Depending on the vehicle equipment and parameterization of the power take-off functions, it is possible to adjust the working speed individually during operation of a power take-off to a working speed between 550 rpm and 750 rpm via the accelerator pedal or the buttons on the multifunction steering wheel, or to raise it to a parameterized value via the idle speed switch (S900), provided that the max. working speed is not exceeded and the min. working speed is not undershot.

 Changing the working speed using the

accelerator pedal

If the accelerator pedal is operated and the position of the accelerator pedal sensor (B44) is thereby changed, the drive control (CPC) control unit (A3) changes the rules for the working speed. It transmits the working speed via the drive CAN (CAN 4) to the engine management (MCM) control unit (A4). In doing so, it takes into account the specified parameters of the sensor and actuator module, cab (SCA) control unit (A7) or the parameterizable special module (PSM) control unit (A22), depending on the vehicle equipment, as well as the current actual engine speed.

The engine management (MCM) control unit (A4) increases the working speed through appropriate actuation of the injection quantity to the desired value and holds this constant.

 Changing the working speed over the multifunctional steering wheel

The working speed can be changed gradually in increments of 20 using the buttons on the multifunction steering wheel. The buttons on the multifunction steering wheel are connected via a LIN bus with the modular switch panel (MSF) control unit (A43), which transmits the entries via the interior CAN (CAN 2) to the central gateway (CGW) control unit (A2). This, in turn, forwards them via the frame CAN (CAN 3) to the drive control (CPC) control unit (A3). The drive control (CPC) control unit (A3) compares the requested working speed with the current working speed, the max. permitted working speed, and the min. permitted working speed (provided these were parameterized). It adapts the rule and transmits it to the engine management (MCM) control unit (A4).

The engine management (MCM) control unit (A4) alters the working speed through appropriate actuation of the injection quantity to the desired value and holds this constant.

 Changing the working speed using the idle speed switch (S900)

One special task in controlling the working speed is taken on by the idle speed control switch (S900).

This allows the constant-rpm control to be switched on, i.e. the engine management (MCM) control unit (A4) sets a specifically parameterized engine speed and keeps it constant, independently of the load.