Abstract: Various embodiments include a method for actuating a piezo actuator of an injection valve of a fuel injection system comprising: determining actuation signals for the piezo actuator using a stored current/voltage characteristic curve for carrying out an injection process; detecting the profile of the current flowing through the piezo actuator during the injection process and the profile of the voltage applied to the piezo actuator during the injection process; adapting the stored current/voltage characteristic curve based at least in part on the detected current profile and the detected voltage profile; and determining actuation signals for the piezo actuator using the stored, adapted current/voltage characteristic curve for carrying out a subsequent injection process.

Abstract: A method is disclosed for determining the idle travel of a piezo-injector which has a piezo-actuator and a nozzle needle which is activated directly by the piezo-actuator. A test pulse is applied to the piezo-actuator, which pulse brings about a continuous increase in the piezo-travel. The time period is measured which passes between the starting of the test pulse and the time when the idle travel is overcome. The idle travel of the piezo-injector is then determined from the measured time period.

Abstract: A method is disclosed for determining the force acting on the nozzle needle of a directly driven piezo injector, in which an electrical voltage is built on the piezo actuator which drives the nozzle needle by means of a charging process. After the charging process has ended, the voltage at the piezo actuator is measured again. A voltage gradient is determined from consecutive voltage values. Conclusions of the force acting on the nozzle needle are drawn from the voltage gradients.

Abstract: A method is disclosed for monitoring the state of a piezoelectric injector of the fuel injection system of an internal combustion engine, the piezoelectric injector having a piezoelectric actuator and a nozzle needle that can be moved by said piezoelectric actuator. The piezoelectric injector can be operated in a partial-stroke mode and a full-stroke mode. In the partial-stroke mode, the curve of an electrical parameter over time is recorded, the maximum value of the curve is determined, a constant parameter value that arises after the presence of the maximum value is determined, the duration between the presence of the maximum value and the reaching of the constant parameter value is determined, the difference between the maximum value and the constant parameter value is determined, and conclusions about the state of the piezoelectric injector are drawn on the basis of the determined duration and the determined difference.

Abstract: A method is disclosed for determining the idle travel of a piezo-injector which has a piezo-actuator and a nozzle needle which is activated directly by the piezo-actuator. A test pulse is applied to the piezo-actuator, which pulse brings about a continuous increase in the piezo-travel. The time period is measured which passes between the starting of the test pulse and the time when the idle travel is overcome. The idle travel of the piezo-injector is then determined from the measured time period.

Abstract: A method is disclosed for determining the force acting on the nozzle needle of a directly driven piezo injector, in which an electrical voltage is built on the piezo actuator which drives the nozzle needle by means of a charging process. After the charging process has ended, the voltage at the piezo actuator is measured again. A voltage gradient is determined from consecutive voltage values. Conclusions of the force acting on the nozzle needle are drawn from the voltage gradients.

Abstract: A method is disclosed for monitoring the state of a piezoelectric injector of the fuel injection system of an internal combustion engine, the piezoelectric injector having a piezoelectric actuator and a nozzle needle that can be moved by said piezoelectric actuator. The piezoelectric injector can be operated in a partial-stroke mode and a full-stroke mode. In the partial-stroke mode, the curve of an electrical parameter over time is recorded, the maximum value of the curve is determined, a constant parameter value that arises after the presence of the maximum value is determined, the duration between the presence of the maximum value and the reaching of the constant parameter value is determined, the difference between the maximum value and the constant parameter value is determined, and conclusions about the state of the piezoelectric injector are drawn on the basis of the determined duration and the determined difference.

Abstract: An optimized CO2 air-conditioning system for a vehicle has individual components designed and/or matched to one another in such a way that if the high pressures in the high-pressure section deviate by up to ±30% from the optimum high pressures, the associated optimum performance figures are reduced by no more than 20%. The individual components include a controllable compressor, a gas cooler, an internal heat exchanger, an evaporator and an accumulator. As a result, a fixed throttle expansion member can be used between the high-pressure and low-pressure sections of the system.

Abstract: An air-conditioning system operated with CO2 for a vehicle has a high-pressure section that is connected to the output of a compressor and includes a gas cooler, a low-pressure section that is connected to the suction side of the compressor and includes an evaporator, and an expansion member connecting the high-pressure section and the low-pressure section. The expansion member has a fixed restrictor with a throttle opening of predetermined length and diameter connected between an inlet from the high-pressure section and an outlet to the low-pressure section whereby under all operating conditions of the system, a pressure of refrigerant in the high-pressure section of the system is limited to values of less than 14 MPa. The restrictor can be connected in parallel with a pressure limiting valve and can include two or more different throttle openings that can be selectively connected for refrigerant flow.

Abstract: An air-conditioning system operated with CO2 for a vehicle has a high-pressure section that is connected to the output of a compressor and includes a gas cooler, a low-pressure section that is connected to the suction side of the compressor and includes an evaporator, and an expansion member connecting the high-pressure section and the low-pressure section. The expansion member has a fixed restrictor with a throttle opening of predetermined length and diameter connected between an inlet from the high-pressure section and an outlet to the low-pressure section whereby under all operating conditions of the system, a pressure of refrigerant in the high-pressure section of the system is limited to values of less than 14 MPa. The restrictor can be connected in parallel with a pressure limiting valve and can include two or more different throttle openings that can be selectively connected for refrigerant flow.

Abstract: An optimized CO2 air-conditioning system for a vehicle has individual components designed and/or matched to one another in such a way that if the high pressures in the high-pressure section deviate by up to ±30% from the optimum high pressures, the associated optimum performance figures are reduced by no more than 20%. The individual components include a controllable compressor, a gas cooler, an internal heat exchanger, an evaporator and an accumulator. As a result, a fixed throttle expansion member can be used between the high-pressure and low-pressure sections of the system.

Abstract: A control device is provided for a refrigerant circuit of an air conditioner, divided by a compressor and a vent element into a high-pressure side and a low-pressure side. The control device includes a high-pressure-side control part and a low-pressure-side control part for controlling one or more controllable high-pressure-side or low-pressure-side system components. The two control parts are coupled with one another, with at least one influential parameter of one control part forming a coupling parameter that is coupled into the other control part as an influential parameter that is effective there as well. The control device is useful for carbon dioxide air conditioners of motor vehicles.