For Merceds-Benz, KARL DEUTSCH developed an innovative ultrasonic measuring instrument to measure the transmission oil level.
The 9-speed automatic transmission (9G Tronic) from Mercedes-Benz promises, in contrast to the previous 7-speed transmission, a reduced fuel consumption of up to 6.5 % and ensures a low engine speed and correspondingly smooth running.
The transmission has been in use in the rear-wheel driven models as well as 4-wheel, hybrid and plug-in hybrid drives since September 2013 and is constantly optimised. In the premium segment, it was the world‘s first 9-speed automatic transmission with a hydrodynamic torque converter. The transmission was developed in-house by Mercedes-Benz.
Conventionally, the transmission oil level is set at exactly 40 °C by means of a mechanical tube with an overflow opening. To do this, the transmission box must be overfilled with transmission oil and the level is checked via a so-called drip pattern.
This procedure is extremely time-consuming and the assessment of the drip pattern is very subjective, which can be a source of error in the measurement. Due to temperature-dependent volume expansion between 20 °C and 80 °C, the transmission oil level fluctuates by up to 20 mm. Especially in warm countries, this is a problem and can lead to an oil level measurement only being able to be carried out in air-conditioned rooms after longer waiting times. In order to increase service-friendliness, Mercedes Benz desired a time reduction for oil level setting/measurement with a simultaneous improvement in the setting accuracy. For these reasons, Mercedes-Benz commissioned KARL DEUTSCH to develop a corresponding measuring device for a faster, more accurate and less error-prone determination of the transmission oil level.
The handling of the measuring device newly developed by KARL DEUTSCH is very simple: A special ultrasonic sensor is connected to the oil pan of the transmission box with the help of a bayonet mount.
The oil sump contains a calming tube, which allows the transmission oil level to be measured during vibrations and even when the vehicle is slightly tilted. The measured value is then compared with the set value in the diagnostic device, taking into account the transmission oil temperature. This eliminates the previous cumbersome process. The exact oil level is obtained very quickly and without great effort, and earlier sources of error can no longer occur. The Mercedes-Benz workshops therefore have an exact value with simultaneous time and cost savings. The KARL DEUTSCH unit offers a further advantage when the transmission box oil level needs to be corrected or the oil needs to be changed: The transmission box is filled to the change oil level from below by means of a pump station. After the engine has been started and the pre-conditioning of the transmission box has been initiated by means of the diagnostic device, the correct oil level can be set quickly. This process can be completed much faster with the help of the innovative measuring device. This means that overfilling and subsequent correction of the oil level is no longer necessary.
We are very proud that KARL DEUTSCH was chosen as a development partner for this task. Mercedes Benz is extremely satisfied with our solution and there are already more than 3000 instruments in use in authorised workshops. The device is also used for the current 8G dual-clutch transmission of the MFA-2 platform. Further development projects are already under discussion