Abstract: An electric motor has a stator (12) as well as a rotor (14) rotatable about a rotation axis (85) and a sensor magnet (82) having an even number of sensor poles (71, 72, 73, 74). The sensor magnet (82) is configured to generate a magnetic flux having a magnetic flux density that changes sinusoidally with respect to the rotation angle. Two analog rotor position sensors (460, 465) are arranged on a support structure (468) at a distance from one another such that, during operation, they generate two sinusoidal signals (B_S1, B_S2) having a phase shift of 90° to each other. A signal generator (90) serves to generate at least one pulse-shaped signal (A, B) from the two sinusoidal rotor position signals (B_S1, B_S2) that are phase-shifted by 90°. The instantaneous rotation speed can be accurately determined from this pulse-shaped signal.

Abstract: An electric motor has a stator (12) as well as a rotor (14) rotatable about a rotation axis (85) and a sensor magnet (82) having an even number of sensor poles (71, 72, 73, 74). The sensor magnet (82) is configured to generate a magnetic flux having a magnetic flux density that changes sinusoidally with respect to the rotation angle. Two analog rotor position sensors (460, 465) are arranged on a support structure (468) at a distance from one another such that, during operation, they generate two sinusoidal signals (B_S1, B_S2) having a phase shift of 90° to each other. A signal generator (90) serves to generate at least one pulse-shaped signal (A, B) from the two sinusoidal rotor position signals (B_S1, B_S2) that are phase-shifted by 90°. The instantaneous rotation speed can be accurately determined from this pulse-shaped signal.

Abstract: An improved drum motor, preferably electronically commutated, features a unitary stationary central shaft (18) supporting a stationary inner stator (52), and an external rotor (49), including permanent magnets (54), secured to an inner surface of a generally cylindrical rotatable casing part (18). This permits variable speed operation while avoiding any need for an internal gear linkage. Safety is improved by making sealing plates (76, 78) at respective axial ends of the casing (14) stationary, and providing an annular peripheral seal (90) around each sealing plate. Respective rolling bearings (24, 44) near each end of the casing (14) facilitate rotation of the external rotor (49) relative to the stator (52), and a clamping arrangement (30) minimizes noise from the bearings.

Abstract: An improved drum motor, preferably electronically commutated, features a unitary stationary central shaft (18) supporting a stationary inner stator (52), and an external rotor (49), including permanent magnets (54), secured to an inner surface of a generally cylindrical rotatable casing part (18). This permits variable speed operation while avoiding any need for an internal gear linkage. Safety is improved by making sealing plates (76, 78) at respective axial ends of the casing (14) stationary, and providing an annular peripheral seal (90) around each sealing plate. Respective rolling bearings (24, 44) near each end of the casing (14) facilitate rotation of the external rotor (49) relative to the stator (52), and a clamping arrangement (30) minimizes noise from the bearings.

Abstract: An improved drum motor, preferably electronically commutated, features a unitary stationary central shaft (18) supporting a stationary inner stator (52), and an external rotor (49), including permanent magnets (50), secured to an inner surface of a generally cylindrical rotatable casing part (18). This permits variable speed operation while avoiding any need for an internal gear linkage. Safety is improved by making sealing plates (76, 78) at respective axial ends of the casing (14) stationary, and providing an annular peripheral seal (90) around each sealing plate. Respective rolling bearings (24, 44) near each end of the casing (14) facilitate rotation of the external rotor (49) relative to the stator (52), and a clamping arrangement (30) minimizes noise from the bearings.

Abstract: An electric motor has a stator and an external rotor (40). Its external rotor (40) has a sensor magnet (54) having a plurality SP of sensor poles (55). The motor also has: at least one rotor position sensor (42, 44) for generating a rotor position signal and a rotor position evaluation arrangement for generating an absolute value for the rotor position, which apparatus comprises an A/D converter (144) having a resolution of at least two bits, the at least one rotor position sensor (42, 44) being connected to the A/D converter. In order to enable obtaining different digital values, even at rotational positions within the angle range of one sensor pole, each analog rotor position sensor signal is converted by the A/D converter into a digital value having at least two bits.

Abstract: An improved drum motor, preferably electronically commutated, features a unitary stationary central shaft (18) supporting a stationary inner stator (52), and an external rotor (49), including permanent magnets (54), secured to an inner surface of a generally cylindrical rotatable casing part (18). This permits variable speed operation while avoiding any need for an internal gear linkage. Safety is improved by making sealing plates (76, 78) at respective axial ends of the casing (14) stationary, and providing an annular peripheral seal (90) around each sealing plate. Respective rolling bearings (24, 44) near each end of the casing (14) facilitate rotation of the external rotor (49) relative to the stator (52), and a clamping arrangement (30) minimizes noise from the bearings.

Abstract: Wash solutions containing Fe(II) and Fe(III) chelate complexes and used for removing NO.sub.x from waste gases are regenerated by treatment with sodium tetrahydroborate.

Abstract: Stabilized water-containing sodium dithionite formulations which have been rendered alkaline have the consistency of a pumpable paste. They additionally contain readily soluble sodium salts and/or potassium salts which are inert to sodium dithionite and whose water-solubility at 20.degree. C. exceeds 500 g/l. These salts are present in the aqueous phase in an amount of not less than 200 g/l. The pastes are useful reducing agents.

Abstract: Sodium dithionite formulations containing inert organic liquids have the consistency of a pumpable paste.

Abstract: In a process for the manufacture of sodium dithionite by reacting sulfur dioxide with sodium formate and aqueous sodium hydroxide solution in the presence of methanol, an aqueous methanolic solution of sodium formate is first produced by reacting carbon monoxide with sodium hydroxide solution in an aqueous medium, containing from 1 to 50% by weight of methanol, based on the amount of water, at from 80 to 120.degree. C. under a pressure of from 10 to 40 bars. The resulting aqueous methanolic solution can be reacted directly, in the conventional manner, with sulfur dioxide and aqueous sodium hydroxide solution to give sodium dithionite.

Abstract: Concentrated dithionite solutions are produced by cathodic reduction of an aqueous solution, containing sulfite and/or bisulfite, which is circulated by pumping. The cathode and anode chambers are separated from one another by a permselective cation exchanger membrane. The catholyte must be circulated at least 10 times per hour and the selective catholyte volume outside the cell, defined asa = V.sub.total -V.sub.C /V.sub.total,Should be less than 0.9.

Abstract: For the preparation of anhydrous sodium dithionite by the reaction of sulfur dioxide with sodium formate and caustic soda in the presence of organic solvents, sulfur dioxide is passed, together with the formate, into a liquid containing all of the caustic soda required for the reaction. This initial liquid may contain, in addition to the caustic soda, a portion of the sulfur dioxide or formate required for the reaction.