Task, In conjunction with AAC
On the left SAM there are two types of input signals:
- Digital signals
- Analog signals
Reading in digital signals:
Depending on how quickly the processor has to respond to signal changes, the signals are read in at shorter or longer intervals.
So that the system does not respond to short-term in interference, the left SAM only incorporates signal changes if the new level value has been read in three times in succession.
Reading in analog signals:
The supply of switches and sensors depends on the current battery voltage. Before reading in a switch/sensor. the processor first reads the unfiltered battery voltage. If this is in the valid range the switch can be read in. After this voltage is set proportional to the switch voltage. So that the system does not respond to short-term interference, the left SAM only incorporates signal changes if the new level value has been read in twice in succession. Sensor
values are transmitted as physical values.
The following sensors are recorded:
- Refrigerant temperature
The A/C temperature sensor is supplied with 5V. The sensor ground is to be selected jointly for the A/C temperature sensor and the Refrigeration pressure sensor. The temperature and pressure also have to be measured at the same time
- Refrigeration pressure
The Refrigeration pressure sensor is supplied with a stabilized 5V. The sensor ground is to be selected jointly for the A/C temperature sensor and the Refrigeration pressure sensor. The temperature and pressure also have to be measured at the same time.
- Outside temperature
and the following information read in made available on the interior bus (CAN B):
- A/C compressor ON
- A/C compressor actuating signal
Actuation of A/C compressor
The A/C compressor is power-controlled steplessly. To switch on the A/C compressor the AAC pushbutton control module sends the switch-on request and the specified value (0-100%) to the left SAM via CAN B. The A/C compressor is current controlled (100% corresponds to 1A). At the same time the expected torque of the A/C compressor is conveyed to the motor electronics (ME-SFI) and ETC control module via the electronic ignition starter switch control module.
The left SAM sends the load increase signal to the motor electronics (ME SFI) via the electronic ignition/starter switch control module and switches the A/C compressor ON after a defined time delay (approx. t = 450 ms).
To switch-off the A/C compressor the AAC pushbutton control module sends the switch-off request and the specified value = 0% to the left SAM via CAN B. At the same time the A/C compressor torque is set to the value 0 and conveyed to the motor electronics (ME-SFI) and ETC control module via the electronic ignition/starter switch control module. The left SAM sends the load increase-signal to the motor electronics (ME-SFI) via the electronic ignition/starter switch control module and switches the A/C compressor off after a defined time delay (approx. 450 ms).
During hard acceleration at the request of the motor electronics (ME-SFI), the A/C compressor is directly controlled to half the request from the A/C pushbutton control module by the left SAM for a defined time (max. t = 10 seconds)
The AAC pushbutton control module receives the acceleration signal as information. If the engine fan is defective and there is a cooling problem at the same (engine temperature too high) the, motor electronics (ME-SFI) requests an emergency shut off of the A/C compressor by the AAC pushbutton control module or left SAM.