DME Control Unit Bosch Med 17.1.6 (Hybrid Manager)
DME control unit Bosch MED 17.1.6 (hybrid manager)On the following pages the incoming sensors and the controlled actuators of the DME control unit are described.
Other sensors
- A pressure sensor for the vacuum system
- A brake pedal sensor
- A sensor for oil level and oil temperature
- CAN - input signals
Other actuators
- Switching valves for thermal management
- An electric water pump for the high-temperature circuit
- An electric water pump for the low-temperature circuit
- An encased main water pump
- An electric vacuum pump
DME control unit Bosch MED 17.1.6 (hybrid manager)
The DME control unit Bosch MED 17.1.6 also contains the hybrid manager, which is responsible for controlling the hybrid components and electric auxiliary units of the engine. Communication between the DME and hybrid manager takes place internally in the common control unit.
External communication with other control units takes place via the 500 kbd CAN-BUS or the diagnostic connection of the vehicle.
Electric auxiliary units
Since the combustion engine does not run continuously, individual auxiliary units are powered electrically in order to guarantee continuous operation:
- Electric high-voltage air-conditioning compressor for cabin air conditioning
- Electric auxiliary vacuum pump for brake power boost
- Electric servo pump for power steering
- Electric auxiliary oil pressure pump for transmission oil supply
- Two electric auxiliary water pumps (one for the high-temperature circuit and one for the low-temperature circuit)
- Electro-hydraulically operated spindle actuator for actuating the decoupler in the drive train
Cayenne S Hybrid-specific driving modes
Six special driving modes
- Driving under exclusively electric power
- Gliding without drive power ("coasting")
- Recovery of brake energy (recuperation)
- Combustion engine-powered driving with load point shift for charging the traction battery
- Boosting (addition of combustion engine and electric machine torques)
- Automatic stopping and restarting of engine when the vehicle is stationary (Auto Start Stop function)
The interaction between the main components of combustion engine, hybrid module (electric machine and decoupler), transmission and battery is controlled during the hybrid-specific driving modes via the hybrid manager. The hybrid manager expands the existing engine control and collects all driving and energy information for the vehicle in order to be able to control the electric machine and the combustion engine for optimum fuel consumption in every driving situation. As the supplier of energy, the battery is neither discharged too exhaustively nor, with respect to the number of cycles, loaded and unloaded too frequently. For this calculation, approx. 26,000 data parameters in total must be defined in the control unit, while around 10,000 are sufficient for conventional engine control.
The DME functions are controlled by the hybrid manager.
- Actuation of the hybrid clutch and the DME activates the Auto Start Stop function for the combustion engine depending on the driver requirements and the vehicle situation
- Definition of functions e.g.:
- Coasting
- Recuperation
- Load point shift
- Boosting
Auto Start Stop function
Thanks to the hybrid technology, a Start Stop function can be integrated into this vehicle concept. In a conventional vehicle with Start Stop system, the vehicle must stop in order to deactivate the combustion engine. With a full hybrid vehicle, the vehicle can be driven electrically. This characteristic enables the Auto Start Stop function to deactivate the combustion engine even when the vehicle is driving or rolling. The combustion engine is activated as required. This may be the case during high acceleration, high speed, high load or low charge state of the high-voltage battery. When the high-voltage battery is in a low charge state, the hybrid system can use the combustion engine with the E-machine as a generator to charge the high-voltage battery. In other cases the full hybrid vehicle can be driven electrically. The combustion engine is then in a Stop phase. This also applies to slow-moving traffic, stopping at a red light, deceleration when driving downhill or coasting of the vehicle. When the combustion engine is not running, it does not consume any fuel and thus cannot produce any emissions. The Start Stop function integrated in the hybrid system increases the efficiency and thus the eco-friendliness of the vehicle. During the Stop phase of the combustion engine, the air conditioning can still be operated. The air-conditioning compressor is part of the high-voltage system.
Coasting
Coasting is possible even at low speeds and occurs as soon as the driver releases the accelerator pedal. The decoupler is disengaged and the combustion engine is switched off automatically in order to prevent the engine drag torque that normally occurs in the deceleration phase. Coasting is thus equated with gliding or rolling without any combustion engine powered or electric drive support.
Recuperation
As soon as the driver actively reduces the vehicle speed, rolls or drives downhill, the hybrid manager separates the combustion engine from the rest of the drive train and switches it off. The E-machine then functions as a generator and first and foremost charges the high-voltage battery. The hydraulic brake system is activated from a defined pedal travel.
NOTE: For further information, see the brochure "Cayenne S Hybrid Training Information", section "DME Hybrid technology".
Load point shift
A load point shift can be carried out by the hybrid manager as a load point increase or reduction.
For a load point increase, the combustion engine provides more torque than the driver setpoint torque, whereby the electric machine of the vehicle compensates for the difference through charging of the high-voltage battery by the combustion engine.
For a load point reduction, the combustion engine provides less torque than the driver setpoint torque and the electric machine of the vehicle compensates for the difference by way of the engine, which results in discharging of the high-voltage battery.
Boosting
Similar to the kickdown function in combustion engines, which makes the maximum engine power available, E-machines and combustion engines deliver their maximum power, which adds up to produce a higher overall value.