|
|
 |
|
Special Requirements regarding Pressure Sensors for the Use in the Development of Racing EnginesThe indicating technology is used in the development of racing engines with similar goals as in the development of standard engines. The main goals of developing racing engines are the thermodynamic optimisation of the combustion and the gas exchange as well as the reduction of the frictional losses. However, the requirements for the measurement technology and particularly for the pressure sensors used in racing engines are substantially higher compared to standard engines, as the measurements have to be made at high accelerations, high speeds or high pressures in the combustion chamber depending on the application (e.g. Nascar, Formula 1 or Racetruck). In the following, the special requirements regarding the properties of the pressure sensors resulting from the application are listed.
- Limited installation space
- Very good signal-to-noise ratio
- Little change in thermal sensibility
- Low deformation sensibility
- Low cyclical drift
- Reduced influence of accelerations
The reproducibility of the measurement results is also a special requirement for the development of racing engines. Often, only small progress is made in the development of racing engines, but these progresses should be proved. This requires the influence of the used measurement instruments from pressure sensor to indicating device on the measurement being as low as possible. Related to the pressure sensor this means a constant product quality without relevant fluctuations regarding the measurement properties during the application.
The following can be said in conclusion. The pressure sensors available on the market today comply with a large part of the described properties. However, there is enough room for improving the pressure sensors, e.g. regarding their lifetime. For this, AVL works continuously on the further development of the pressure sensors.
 | | Figure 1: GR14D (M5) |
The above mentioned special requirements for pressure sensors are described in more detail below:
| Limited installation space | | The limited installation space within the cylinder head of racing engines, especially F1 engines, only allows the installation of pressure sensors with small diameters. M5 has established itself as standard in this area. | | Very good signal-to-noise ratio | | The elevated signal-to-noise ratio requested by users is realized by using crystals which were especially developed for the use in piezo-electric pressure sensors. | | Little change in thermal sensibility | | The crystals have to satisfy the requirement of a thermal sensitivity change which is as low as possible, ideally it should be within a scatter band of max. ± 2% when they are used at temperatures of up to 400°C. | | Low deformation sensibility | | Deformation sensitivity is one possible source of errors. Deformations at the installation position can result in a pre-tension of the measuring elements in the sensor and thus lead to a pressure-independent load loss distorting the measuring result.
Ideally a sensor with reduced deformation sensitivity has been constructed in such a way that the measuring elements are mechanically decoupled from the thread in order to prevent a transmission of e.g. cylinder head deformations to the measuring elements. | | | | Cyclic drift as reaction of the sensor to the heat input from combustion with the resulting temperature gradient at the membrane can be reduced by using a specific membrane geometry dissipating most of the heat via the sensor housing. | | Reduced influence of accelerations | | In addition, the measurement accuracy can be improved by reducing the influence of unwanted accelerations e.g. through valve knocking by using an acceleration compensation. |
|
|
|
|