The gauge of the mass expense of air. Device

The mass flow sensor can be of different types. The most popular are ultrasonic, mechanical (vane type), thermo-anemometric and others.

The mass air flow sensor "VAZ" (thermo-anemometric type) includes a sensing element. It is presented in the form of a thin film. It houses temperature sensors, a resistor (heating). In the center of the film there is a heating section, the temperature level of which is controlled by a temperature instrument. On the side of the air flow and symmetrically on the opposite side on the surface of the film there are 2 more temperature sensors. They show the same temperature when there is no flow. When air appears, the first sensor is cooled. The temperature of the second device is practically unchanged. This is due to the heating of the flow in the heating zone. A differential signal is supplied from the sensors, which is proportional to the mass of the transmitted airflow. By electronic circuit, the signal is converted into a constant voltage. It is proportional to the mass of air. This design is called Hot Film. Advantages of this device - the ability to accurately measure the air flow, as well as register the return flow. Among the shortcomings, experts note a low reliability in case of moisture or contamination of the device.

In the systems used previously, the mass flow sensor included a sensing element made in the form of a thread. At the output, the signal had a certain frequency. In other words, with the air flow, the frequency of the pulses changed, and not the voltage. Such a mass air flow sensor was not very accurate, it did not allow to register a reverse air flow. However, these shortcomings were compensated by its high reliability.

The mass flow sensor is a very important part of any control system. The incoming signal from it starts the process of calculating the cycle filling of the cylinder, which is eventually recalculated into the pulse duration when the nozzles are opened.

It should be noted that sensors of various types were installed on VAZ cars: SIEMENS, BOSCH, Russian and GM. From 1999 to 2004, two types of devices, 004 and 037, were installed on the conveyors. They show different values of the output voltage (calibration) at the same flow rate. Replacement of the first to the second is possible only if the calibration tables are replaced in the firmware. The same applies to the new 116 sensor, installed in 2005 serially. According to the current documentation, three modifications are allowed on the conveyor.

The first (historically) sensor 004 was applied in projects with four calibrations. The first two projects can easily be determined by external parameters, since they are not equipped with a neutralizer and they use a resonant detonation device. At some point, the first two projects ceased to be produced, and projects with the remaining two calibrations were equipped with sensors 037. This modification differs from the first modified internal channel. This refinement made it possible to eliminate the pulsations of the air flow, which were formed earlier in the laminar flow in the intake manifold.

Since 2005, the serial use of the 116. sensor was started. The modification was intended for projects with controllers of the late generation Bosch and January (Russian analogs).

The sensor is supplied exclusively assembled, with a code. There is a marking with a green circle. The design of the element itself, in comparison with the previous modifications, is changed. To fix the sensor body, unidirectional bolts are used.