Abstract: Non-proton cationic impurities are removed from the ionomer in a proton exchange membrane of an electrochemical cell and from the anode side and cathode side catalyst layers. A supply path for an anode feed to the ionomer on the anode side of the proton exchange membrane and a supply path for a cathode feed to the ionomer on the cathode side of the proton exchange membrane are provided. A regenerating fluid with acidic pH is brought into contact with the ionomer on the cathode side of the proton exchange membrane to accomplish an ion exchange of the non-proton cationic impurities with protons and thus remove the non-proton cationic impurities from the ionomer into the regenerating fluid. This removes the non-proton cationic impurities from the ionomer of the electrochemical cell without increasing the risk of corrosion and without interrupting the process of the electrochemical cell.

Abstract: Non-proton cationic impurities are removed from the ionomer in a proton exchange membrane of an electrochemical cell and from the anode side and cathode side catalyst layers. A supply path for an anode feed to the ionomer on the anode side of the proton exchange membrane and a supply path for a cathode feed to the ionomer on the cathode side of the proton exchange membrane are provided. A regenerating fluid with acidic pH is brought into contact with the ionomer on the cathode side of the proton exchange membrane to accomplish an ion exchange of the non-proton cationic impurities with protons and thus remove the non-proton cationic impurities from the ionomer into the regenerating fluid. This removes the non-proton cationic impurities from the ionomer of the electrochemical cell without increasing the risk of corrosion and without interrupting the process of the electrochemical cell.

Abstract: A method of manufacturing gas diffusion layers (GDL) with a defined pattern of hydrophobic and hydrophilic regions is used to produce electrically conductive porous materials with distributed wettability. The method includes a) Coating the external and internal surfaces of a porous base material made of carbon fiber or Titanium with Fluoroethylene-Propylene (FEP) and/or perfluoroalkoxy (PFA) and/or Ethylene-Tetrafluoroethylene (ETFE) or any other hydrophobic polymer; b) Exposing the coated material to irradiation through a blocking mask such that only parts of the coated porous material are exposed; and c) Immersing the previously exposed material in a monomer solution and heating to a temperature higher than 45° C., resulting in the graft co-polymerization of monomers on the FEP layer.

Abstract: The invention relates to a setting device for a ventilation flap (12, 12a, 2b) in an air duct, particularly in a heating and ventilation system of an automobile, with an electric motor (2) executing setting movements and with a control unit (3) for the electric motor (2). In order to minimize the outlay in terms of assembly and the replacement parts to be kept available, there is provision for designing the electric motor (2) as a stepping motor activated by output signals from a control unit (3) adjacent to this stepping motor, and the control unit (3) has encoding inputs (K1, K2) for selecting the direction of rotation and/or the rotary angle.

Abstract: A device for driving a positioning element via a stepping motor is described. This device makes it possible to continue operating the stepping motor in conjunction with its use as an encoder during phases without electrical control, so that the position last reached under electrical control, with a zero-current change in the position, possibly as a result of manual operation of the positioning element that is rotationally or frictionally coupled with the motor rotor, is constantly updated so that the control electronics is informed at all times of the actual position from which the stepping motor is to be controlled electrically to assume a new position. The device not only permits eliminating indexing devices that are subject to wear, but also allows automatic return, for example of a positioning element to its previous starting position after it has been shifted or adjusted from by an outside influence.

Abstract: A driving device for controlling the driving frequency for a stepping motor includes a voltage control pulse generator for producing electrical pulses for driving the stepping motor. The pulse generator includes an RC network providing a time base for the pulse width and the operating frequency of the electrical pulses. The RC network includes at least one controllable resistance and a capacitor connected to control the controllable resistance by the charging and discharging of the capacitor.

Abstract: A pulse-width modulator is used to control the sequence generator of a stepping motor to stabilize the stepping motor. One input to the pulse-width modulator is a cyclic sequence of pulses. The other input to the pulse-width modulator is an error-correction signal. The error-correction signal is proportional to variations about an average of the sum of the currents produced by the sequence generator. The error-correction signal is used by the pulse-width modulator to modulate the duration of individual pulses in the cycle sequence of pulses to produce a sequence of pulses of variable duration. The pulses of variable duration serve to control the sequence generator and stabilize the stepping motor.

Abstract: In an apparatus and method for preventing instability of a stepper motor operated by a plurality of alternating currents of different respective phases and controlled by a sequence of control pulses, the control pulses defining an angular parameter of the stepper motor, the steps include determining the sum of the phase currents, transforming the sum of the phase currents into a voltage fluctuating about an average value, determining the average voltage, and thereafter feeding back the fluctuating voltage so as to angle-modulate said control pulses.

Abstract: Circuitry for measuring the torque of a stepping motor is disclosed. The circuitry is based on the fact that the decay time of the current flowing through the stator coils is a function of the torque of the stepping motor.