Patent GB-808764-A (GB)
Title: Improvements in electrostatic devices
IPC: H02H1/00
Filed: 1955-05-23
Abstract: 808,764. Electrostatic generators and motors. KRAWINKEL, G. H. May 23, 1955 [June 3, 1954; June 10, 1955], No. 14847/55. Class 35. [Also in Groups XXXVI and XXXVII] The invention relates to devices which depend on a so-called " gradient e effect " which is explained with reference to Fig. 1. Two dielectrics with dielectric constants E 1  and e 2  (e 1 >e 2 ) are located in an electric field F. A force P is produced in their boundary layer which is perpendicular to the boundary surface and acts from higher to smaller dielectric constant. The force is independent of the direction of the applied field though when the field is perpendicular to the boundary surface (as shown in Fig. 1) the effect is known as the " normal gradient e effect " and when it is parallel to the surface it is known as " transverse effect ". An extension of the " transverse effect " arises with the use of liquids of variable dielectric constant (e.g. nitro benzene). Fig. 4 shows an arrangement where two conducting plates 4 and 5 are arranged at an angle so that the application of a voltage between them produces an electric field which increases from top to bottom. A fluid whose dielectric constant K F  is dependent on the applied field is introduced, whereupon a gradient in the dielectric constant occurs leading to " gradient e " forces which displace the fluid in and out of the openings 12. Electrostatic switches; electrostatic voltmeters.- In Fig. 2 a membrane 3 is arranged between two members 1 and 2 the inner faces of which have metal coatings 4 and 5, and which are provided with apertures 8. End plates 9 and 10 are fitted providing two inner chambers and two outer chambers connected by the apertures 8, and the outer chambers are interconnected by a tube 12. The two chambers on the left of the membrane are filled with a liquid of dielectric constant K 1 , while those on the right with K 3 . The membrane has a constant K 2 , and K 1 , K 2 , K 3 . A mercury pellet 14 in the tube 12 separates the two liquids. On application of a voltage between 4 and 5 forces are produced on the surfaces of the membrane distending it to the right and the movement is transmitted to the mercury pellet which makes contact with contacts 15, 16, 17. In a modification (Fig. 5, not shown), the left face of membrane 3 is provided directly with a metal coating, and the " gradient e " forces act only on the right-hand side. The arrangement in Fig. 2 may be used as an electrostatic voltmeter since the position of the mercury thread indicates the applied voltage. The movement obeys a square law but the indicator may be made linear by using a tube of varying crosssection. The arrangement of Fig. 4, involving the " transverse gradient e effect " may be used as a switch or voltmeter by connecting contact means or indicating means similar to those of Fig. 2 to the tubes 12. A relay involving the " transverse gradient e " effect is shown in Fig. 6. A liquid of variable dielectric constant is interposed between a metallized membrane 32 and a metal coated dome-shaped wall 21. Application of a voltage produces a flow of the liquid towards the crown of the dome causing the membrane to distend, the movement being transmitted to the membrane 46 to close contacts 27 and 31. Electrostatic motors.-Fig. 8 shows a means for producing a flow of liquid which may be used to drive a turbine wheel 52. Part of the system comprises two metallic members 47, 48, one of which has a saw-tooth outline. A liquid dielectric of variable dielectric constant fills the system. On applying a voltage between 47 and 48 a variable field is produced along each step leading to a variation in the constant and a subsequent " gradient e " force tending to move the liquid. The effect due to a number of steps is cumulative since after passing the peak of a saw-tooth where under a strong field a high degree of orientation occurs, the liquid passes to a place of low field giving a low degree of orientation and a consequent effect in the dielectric constant. Capacitors.-A variable capacitor may also be produced incorporating the gradient e effect, wherein the pressure or suction forces introduce a liquid dielectric to a greater or lesser degree into an air capacitor.