US3396587A

US3396587A - Gyroscopes

Info

Publication number: US3396587A
Application number: US539301A
Authority: US
Inventors: Gresham John Thomas
Original assignee: FMC Corp
Current assignee: FMC Corp
Priority date: 1966-04-01
Filing date: 1966-04-01
Publication date: 1968-08-13
Anticipated expiration: 1985-08-13

Description

United States Patent 3,396,587 GYROSCOPES John Thomas Gresham, Skillman, N.J., assignor to FMC Corporation, New York, N.Y., a corporation of Delaware No Drawing. Filed Apr. 1, 1966, Ser. No. 539,301 3 Claims. (Cl. 74-5.5)

This invention relates to floated control instruments, particularly floated gyroscopes in which the flotation fluid is an organic mercury compound.

A floated gyroscope is one in which the rotor is encased in a float. The density of the flotation fluid is chosen to match the density of the float. Such a construction enables the float to rotate about its pivot with an exceedingly low degree of friction. The gyro fluid also protects the assembly from shock, provides a damping function and a heat transfer medium which serves to dissipate heat generated by the rotor. Where the clamping efl ect on the precession of the float is developed primarily by the fluid itself, it is generally preferable that the fluid exhibit high viscosity. However, when damping is not desired or Where electronic or orifice damping is employed, low viscosity liquids are preferred.

In addition to the above described use in a single gyroscope, a gyro fluid may be employed in a system wherein one or more gyros or accelerometers and associated equipment are mounted on a platform which is floated in the liquid. Fluids for this application are usually dense, low viscosity liquids for flotation only.

Liquids suitable for use in gyroscopes must possess certain critical physical characteristics and in this connection it is essential that the liquids exhibit high density, at least about 1.6 g./ml. The higher the density the more useful the fluid, since this permits more inertia to be built into the rotor without imposing higher loads on the pivot hearing. A higher density fluid by the same token allows size reduction at the same amount of inertia (and sensitivity of the gyro). A second parameter of such liquids is that they exhibit Newtonian behavior, i.e., be independent of the shearing rate. Preferably the liquid also should be relatively insensitive in viscosity to tem perature variations. It must, of course, remain serviceable over the operational temperature range of gyroscope. Finally, it is essential that the liquid remain stable While in use since any degradation or breakdown may form decomposition products which may corrode the metal components and parts of the gyroscopes.

Because of the stringent specifications required of gyro fluids, it has been exceedingly dificult to find suitable materials. Those in general use today are based on fluorocarbons since these constitute one of the more stable classes of fairly dense liquid compounds. The high viscosity fluids are normally telomers of CFCl=CF and CFBr=CF having densities of about 1.7 and 2.4 g./ml., respectively. Where low viscosity liquids are called for, low molecular ends of the telomerization product of the olefins are sometimes employed; a volatile fiuorinated cycloether having the empirical formula C F O and a density of 1.7602 g./ml. at 25 C. is also a preferred choice. Halogenated hydrocarbons other than fluorinated hydrocarbons have been conisdered but are generally unsatisfactory because of their reactivity with metals and sensitivity to hydrolysis and thermal decomposition.

With a view to developing improved gyro fluids We now have discovered a class of organic mercury com pounds which exhibit the aforesaid parameters to a marked degree and the provision of these compounds and their use as gyro fluids constitute the principal object and purpose of this invention. Other objects and purposes will become manifest subsequently.

The organic mercury compounds as contemplated herein are di(alkylmercuri)alkanes wherein the alkyl moiety is desirably methyl while the alkane portion is preferably selected from the class consisting of linear alkanes having from 1 to 2 carbon atoms and a cycloalkane as represented by cyclopropane. The compounds can be visualized more readily by reference to the following general formula:

HgCHa wherein Z designates an alkane hydrocarbon residue which may be a lower linear alkane such as CH or CH CH and a cycloalkane such as -CHCH The novel organic mercurials herein are prepared by reacting a metal alkyl with an alkylmercuric halide and separating the resulting di(alkylmercuri)alkane from the metal halide by-product. Purification of the organic mercury compound can be achieved by such well known techniques as sublimation, distillation, crystallization, chromatography or combinations thereof.

The following non-limiting examples are illustrative of how the compounds of the invention can be obtained.

Example 1.Dz'(methylmercuri) methane HgCHa HECHQ To 0.1 mole of di(iodomercuri)methane in dry tetrahydrofuran is added 0.25 mole of methyllithium, the temperature being maintained at about 0 C. during the addition. After stirring for several hours the resulting mixture is allowed to warm up to room temperature. The di- (methylmercuri)methane is then isolated using any of the purification techniques commonly employed in the art.

The di(iodornercuri)methane is prepared following a modified procedure of J. Sakurai, J. Chem. Soc., 39, 485 (1881): Thus, a stirred mixture of 1 mole of mercury, 0.15 mole of methylene iodide and l g. of mercuric iodide is irradiated with a sun lamp. When the slurry solidifies, 1,2-dimethoxyethane is added and the mixture irradiated overnight. The solids are mixed with 10% potassium iodide to remove mercuric iodide and Washed with water and acetone. Bis(iodomercuri)methane is obtained by recrystallization of the crude product from hot methylene iodide.

Example 2.-1,1-di(methylmercuri) ethane HgCH;

CHSCH HgCHa This compound is prepared following the procedure of Example 1 'but substituting ethylidenedimercuric chloride, CH CH (HgCl) for di(iodomercuri)methane.

The requisite ethylidenedimercuric chloride is obtained using the synthesis described in J. Org. Chem., 29, 2742 (1964): g. of boron trifluoride etherate in 250 ml. of tetrahydrofuran is added under nitrogen atmosphere over a period of /2 hour to a stirred slurry of 15.8 g. of sodium borohydride in ml. of diethylene glycol and 250 ml. of tetrahydrofuran cooled in an ice bath. The mixture is stirred 20 minutes at 20 C., cooled in an ice bath and 92 g. (0.5 mole) of dibutylvinylboron-ate is added in /2 hour. After two hours at 20-25, the mixture is cooled in ice and ml. of n-butanol added in one hour. At the end of 30 minutes at room temperature, hydrogen evolution had ceased. The mixture is cooled in ice and treated 3 with 500 ml. of water and then 271 g. of mercuric chloride.

With cooling, a solution of 40 g. of sodium hydroxide in 200 ml. of water is added dropwise at such a rate that the yellow color of mercuric oxide remains discharged. After filtration overnight on a large Buchner funnel to remove mercuric chloride, the filtrate is dilute-d with a liter of water and concentrated at 20 mm. to remove most of the organic solvents. The crude product is collected by filtration and washed with acetone. Additional product is obtained by diluting the mother liquors to about 3 liters, filtering, and extracting the mercurous chloride precipitate with dimethylsulfoxide followed by filtration of the solution diluted with acetone and water.

Example 3.1,2-di(m'ethylmercuri)cyclopropane HaCHg HgCHa HO-CH Hz This compound is prepared by adding methylmercuric bromide to the Grignard reagent of 1,2-dibromocyclopropane. The unreacted magnesium is removed from the reaction mixture after which two equivalents of methylmercuric bromide are added in small portions keeping the temperature at about -10 C. At the end of the addition stirring is maintained for several hours while allowing the reaction mixture to come to room temperature. The 1,2- di(methylmercuri)cyclopropane is then isolated from the reaction mixture.

The Grignar'd reagent of 1,2-dibromocyclopropane is prepared by a synthesis similar to that described in J.A.C.S., 82, 6375 (1960). In this procedure 11 g. of 1,2- dibromocyclopropane is added with stirring to 40 ml. of anhydrous ether and 2.9 g. of 99.99% magnesium. After the reaction has ceased, a quantity of magnesium remains as residue.

1,2-dibromocyclopropane is a known chemical material obtained by the bromination of cyclopropene in accordance with a procedure set forth in J.A.C.S., 82, 6375 (1960). This method involves introducing a stream of cyclopropene and nitrogen into a solution of carbon tetrachloride and bromine at 0 until the bromine color is dis wherein Z designates an alkane hydrocarbon residue selected from the class consisting of lower alkane and cyclopropane.

2. A gyroscope comprising a gyroscope float suspended in an organomercury compound of the formula:

HgOHa wherein Z designates an alkane hydrocarbon residue selected from the class consisting of lower alkane and cyclopropane. 3. A guidance system containing a platform suspended in an organomercury compound of the following formula:

wherein Z designates an alkane hydrocarbon residue selected from the class consisting of lower alkane and cyclopropane, said platform having mounted thereon at least one gym and associated equipment.

No references cited.

C. J. HUSAR, Primary Examiner.

Claims

1. A CONTROL SYSTEM COMPRISING A CONTROL ELEMENT IN OPERATIVE CONTACT WITH A HIGH GRAVITY FLUID WHICH IS AN ORGANOMERCURY COMPOUND OF THE FOLLOWING FORMULA: