It has been shown that appropriate regulation of parameters of the gas supply system control algorithm allows to reduce the emission of selected components of the exhaust gas (carbon monoxide [CO], hydrocarbon [HC], and oxides of nitrogen [NOx]). The test engine met the Euro 6 standard on petrol and was equipped with an additional alternative multipoint fuelling system for multipoint injection (MPI) of the gaseous phase liquefied petroleum gas (LPG). The tests are comparative in nature. The first test to compare LPG petrol fuelling was carried out in the New European Driving Cycle (NEDC) where small differences in emissions were shown. The second part of the test compared emissions in the Worldwide harmonized Light vehicles Test Cycle (WLTC), wherein the initial phase there was a significant difference in emissions to the detriment of the gas supply. An innovative approach was therefore proposed to correct settings in the gas system control algorithm. In the first option, the settings for the multiplier of the opening time of LPG and petrol injectors were adjusted, resulting in a decrease in HC and NOx emissions with an increase in CO. In the second variant, the connection between the reducer and the engine intake manifold was removed, which increased the HC and NOx emissions, with a decrease in CO compared to the previous variant. In the third variant, the connection between the reducer and the engine intake manifold was restored and several coolant temperature threshold adjustments were made when switching from petrol to LPG. As a result of the corrections made in the gas system control algorithm during WLTC implementation, HC emissions were lower by 10.2%, CO by 21.2%, and NOx by 68.2% compared to the initial test.

The paper presents research related to the functional features of a novel three-layer circular piezoelectric actuator/sensor. The outer layers of the transducer are made of non-piezoelectric material. The middle layer comprises two elements—a piezoelectric disk, and a ring made of non-piezoelectric material. The additional external passive layer has a very important function; it protects the transducer’s electrical components against damage caused by external factors. Also, if sparking on the transducer wires or electrodes occurs, this layer prevents fire. So far, there is no analytical model for such a transducer. Closed-form analytical equations are important tools for predicting and optimizing the operation of devices. Thus, using both the Plate Theory and constitutive equations of piezoelectric materials, an analytical formula describing transducer deflection as a function of electrical loads has been found (electromechanical characteristic of the transducer). In addition, it is worth noting that under certain assumptions, the developed analytical model can also be used for two-layer transducers. The tests carried out show satisfactory compliance of the results obtained through the developed solution with both literature data and numerical data. Moreover, based on the obtained analytical model, the effect of selected non-dimensional variables on the actuator performance has been examined. These parameters include dimensions and mechanical properties of both piezoelectric disk and passive plates and strongly influence the behavior of the transducer.