US3368962A - Apparatus for decontaminating hydraulic systems - Google Patents

Description

Feb. 13, 1968 l. R. KRAMER APPARATUS FOR DECONTAMINATING HYDRAULIC SYSTEMS Filed April 30, 1962 ED E Qsqk QSE Sui INVENTOR. IRVIN R. KRAMER ATTORNEY United States Patent 3,368,962 APPARATUS FOR DECONTAMINATING HYDRAULIC SYSTEMS Irvin R. Kramer, Baltimore, Md., assigmor to Martin- Marietta Corporation, Baltimore, Md., a corporation of Maryland Filed Apr. 30, 1962, Ser. No. 191,122 9 Claims. (Cl. 204299) My invention relates to hydraulic systems and, more particularly, to a method and a means whereby impurities in a high dielectric constant fluid are prevented from accumulating at critical points in a hydraulic system and are removed therefrom.

The terms critical points, critical areas and critical parts as I have used them herein shall be understood to refer to particular sections of a hydraulic system wherein an accumulation of foreign particles may be expected to adversely affect system operation. The hydraulic systems referred to herein shall be understood to be systems utilizing a high dielectric constant fluid.

Foreign particles present in hydraulic fluids often cause unsatisfactory system operation and may result in complete system failure. It is important that hydraulic fluids be maintained relatively free of such impurities and further that any impurities, which are initially present in the fluid or which develop in the course of operating such systems, be prevented from accumulating at the critical areas of the system. Many techniques have been developed and are presently being utilized to decontaminate hydraulic fluids. All of these methods employ a means for collecting the foreign particles at a designated point in the system. However, very little attention has been devoted to the problem of automatically removing impurities from critical areas where they have collected and/ or to preventing the accumulation of such particles in these areas in the first instance. Consequently, even though these problems have long been recognized, the critical applications being made of hydraulic systems in todays space age are continually emphasizing the limitations of systems heretofore devised.

Contaminating agents in hydraulic fluids generally comprise fine particles suspended in the fluid. I have determined that these particles possess an electrical charge, some being positively charged While others are negatively charged. My invention, hereinafter described in considerable detail, takes advantage of this phenomenon to furnish a simple and extremely effective method for decontarninating dielectric hydraulic fluids. One of the features of my invention is the collecting of foreign particles from the fluid and it will be seen that other features of my invention, While primarily performing other and novel functions, in effect cooperate to accelerate this process.

It is therefore the primary object of the present invention to provide a method for preventing foreign particles in a hydraulic fluid system from accumulating at critical points of the system. An additional object is to provide a method whereby foreign particles present in a hydraulic fluid system may be effectively removed therefrom. Another object is to provide a simple and efficient means whereby foreign particles initially present in the hydraulic fluid or which develop in the course of system operation may be prevented from accumulating at critical points of the system and continually and effectively removed from the system. These and other objects and advantages of my invention will become apparent as the following description is read in connection with the accompanying drawings in which:

FIGURE 1 is a diagrammatic view of a typical section of a hydraulic system incorporating the principles of my invention;

3,368,962 Patented Feb. 13, 1968 FIGURE 2 is a diagrammatic view showing the principles of my invention being utilized to prevent the accumulation of foreign particles on the critical areas of an angle needle valve; and

FIGURE 3 is another diagrammatic view showing the principles of my invention being utilized to assure the reliable operation of a fixed orifice.

My invention basically contemplates placing an alternating electrical charge on the critical areas of a hydraulic system to repel electrically charged foreign particles away from such areas and collecting these particles on positively and negatively charged electrodes immersed in the hydraulic fluid at a selected point.

Referring first to FIGURE 1, a section of a typical hydraulic system is shown in which a check valve 4 has been connected to piping 5 by a coupling sleeve 6. In the type of check valve illustrated, a poppet 7 is seated against a valve body 8 by the force exerted on it by a spring 9. When the fluid pressure on a face 10 of the poppet 7 is sufficient to overcome the force of the spring 9, the valve is opened by the poppets being displaced in the direction of the fluid flow. The fluid then flows through the ports 11 provided in the poppet 7, into chamber 12 and on through the hydraulic system. In the closed position, I seat the poppet 7 against a cylindrical member 13- which is disposed in a recess 14 provided in the valve body 8. Interposed between the cylindrical member 13 and the valve body 8 is a sleeve 15 of rubber or any other suitable dielectric material. A bearing surface 16 of the cylindrical member 13 is tapered to the same angle as the conical annular edge 17 of the poppet 7 in order that there will be no flow of fluid through the valve when the poppet is seated against the cylindrical member 13. A source of alternating electrical energy 18 has one of its terminals connected to the cylindrical member 13 by a line 19, which passes through an aperture 20 suitably provided in the valve body 8. The other terminal of the source of alternating electrical energy 18 is connected to ground at 21.

A tank 22 is connected to the check valve 4 by the coupling sleeve 23 and to the piping 5 by the coupling sleeve 24. The tank 22 is open at the top, being provided at this point with an outwardly extending annular projection 25. It should be noted that this tank 22 may be in fact the systems fluid storage tank. A cover 26 seats on the outwardly extending annular projection 25 of the tank 22, a gasket 27 being interposed therebetween so as to provide an effective seal for the hydraulic fluid contained in the tank. A plurality of bolts 28, which pass through holes suitably provided in the cover 26, the gasket 27 and the annular projection 25, fasten the cover 26 to the tank 22 maintaining the necessary pressure on the gasket 27. The cover 26 is provided with two cylindrical bores 29 and 30 which pass therethrough. Extended into the tank 22 through the cylindrical bores 29 and 30 are two electrodes 31 and 32. The electrodes 31 and 32 are made of any suitable conductive'material, such as copper, and are provided with extensions 33 and 34. Interposed between the electrodes 31 and 32 and the cover 26 are sleeves 35 and 36 which also are provided with extensions 37 and 38, said extensions 37 and 38 being interposed between the electrode extensions 33 and 34 and the tank cover 26. The sleeves 35 and 36 are of rubber or any other suitable material which serves both as an electrical insulator and as a hydraulic seal. A plurality of screws 39 pass through holes provided in each of-the electrode extensions 33 and 34 to secure the electrodes 31 and 32 to the tank cover 26. The screws 39 are suitably insulated (not illustrated) from the electrodes 31 and 32 in order that there will be no electrical connection between the electrodes and the tank cover 26. A source of direct electrical energy 40 is 3 connected to the electrodes 31 and 32 at points 41 and 42, respectively.

The most critical area of the check valve 4 is the hearing surface 16 against which the poppet 7 seats to prevent the flow of fluid through the valve. Should foreign particles accumulate on the bearing surface 16, the poppet 7 will not scat properly and leakage will occur. In operation, the cylindrical member 13 of the check valve 4 is connected to the source of alternating electrical energy 18 and the electrodes 31 and 32 are connected to the source of direct electrical energy 40 as illustrated in FIGURE 1. It will thus be seen that the cylindrical member 13, and most important the bearing surface 16 thereof, will be alternately charged with a positive and negative potential. In addition, the electrode 31 will be charged with a positive potential while electrode 32 will be charged with a negative potential. The hydraulic fluid flows through the system carrying positively and negatively charged foreign particles through the check valve 4 and into the tank 22. When the cylindrical member 13 is positively charged, positively charged foreign particles present in the hydraulic fluid in the vicinity thereof will be repelled away from the bearing surface 16 toward the center of the hydraulic stream and carried thereby away from this area. When the cylindrical member 13 becomes negatively charged, negatively charged foreign particles present in the hydraulic system in the vicinity thereof will be repelled away from the bearing surface 16 toward the center of the hydraulic stream and carried thereby away from this area. This action prevents foreign particles carried by the hydraulic fluid from accumulating on the bearing surface 16, the critical area of the check valve 4.

As the foreign particles suspended in the hydraulic fluid are carried thereby into the tank 22, those which are positively charged are attracted by and collected on the surface of the electrode 32. Simultaneously, those which are negatively charged are attracted by and collected on the surface of the electrode 31. At convenient intervals in the systems operation when the hydraulic system can be or is shut down, the tank cover 26 with the electrodes 31 and 32 mounted thereon is removed from the tank 22 after first unfastening the bolts 28. The foreign particles are removed from the electrodes 31 and 32 and the cover 26 replaced on the tank 22.

In FIGURE 2, a typical section of a hydraulic system has been illustrated consisting of piping 43 and an angle needle valve 44. The piping 43 is electrically insulated from the needle valve 44 by use of plastic coupling sleeves 45 and rubber gaskets 46 or by any other suitable means. A handle 47 is formed of any non-conducting material such as plastic. The needle valve 44 is connected to one of the terminals of a source of alternating electrical energy 48 by a line 49. The other terminal of the source of alternating electrical energy 48 is connected to ground at 50. A needle 51 seats against a similarly tapered bearing surface 52 of the valve body 53 and, in order to insure proper operation of the valve, foreign particles should be prevented from accumulating in this area. It will be seen that when the needle valve 44 is connected to the source of alternating electrical energy 48 as illustrated in FIGURE 2, the needle 51 and the bearing surface 52 will be alternately charged with a positive and a negative potential. When positively charged, positively charged foreign particles present in the hydraulic fluid in the vicinity of these parts of the needle valve 44 will be repelled from the surfaces of these parts toward the center of the hydraulic stream and carried thereby away from this critical area of the valve. Similarly, negatively charged foreign particles present in the hydraulic fluid in the vicinity of these parts of the needle valve 44 will be repelled from the surface of these parts toward the center of the hydraulic stream and carried thereby away from this critical area of the valve, when these parts become negatively charged. This alternating charge prevents foreign particles from accumulating on either the bearing surface 52 or the needle 51 and permits the proper seating of the needle when it is intended that the valve should cut-off the flow of fluid through the system.

My invention is particularly useful in assuring the reliable operation of fixed orifices such as those which are employed in most servo valves. Referring to FIGURE 3, a typical fixed orifice 54 is shown positioned in a tubular member 55. However, in my invention, I form the orifice 54 of an electrical conducting material and insulate the orifice from the tubular member 55 by a sleeve 56 of rubber or any other suitable dielectric material. The orifice 54 is connected to one terminal of a source of alternating electrical energy 57 by a line 58 which passes through an aperture 59 provided in the tubular member 55. The other terminal of the source of alternating electrical energy 57 is connected to ground at 60. The accumulation of foreign particle in the inner surface 61 of the orifice 54 over a period of time would adversely affect the performance of the orifice. However, alternately placing a positive and negative charge on the orifice 54 will prevent such an accumulation from forming. When the orifice 54 is charged positively, positively charged foreign particles present in the hydraulic fluid in the vicinity of the orifice 54 will be repelled away from the inner surface 61 of the orifice toward the center of the fluid stream and carried thereby away from this area. When the orifice 54 is charged negatively, negatively charged foreign particles present in the hydraulic system in the vicinity of the orifice will be repelled away from the inner surface 61 of the orifice toward the center of the fluid stream and carried thereby away from this area.

The sources of alternating electrical energy 18, 48, and 57 in FIGURES l, 2 and 3, respectively, should be of relatively low frequency. This is desirable to permit the foreign particles which are repelled away from the surfaces of the critical parts of the system to be carried a considerable distance downstream by the hydraulic fluid before the potential on the critical parts reverses and attracts such particles. For optimum results the frequency should be low enough to permit a particular particle to flow completely through a critical part before the potential reverses. This frequency naturally will depend upon the velocity imparted to the particle by the fluid stream and the length of the longest critical part of the system. It have determined that excellent results can be obtained in typical aircraft hydraulic systems using a source of alternating electrical potential having a frequency of approximately 2 cycles per second.

Although my invention basically consists of, and the attached drawings and my description thereof to this point have been concerned with, a process and apparatus wherein an alternating electrical charge is placed on a critical part of a hydraulic system to alternately repel positively and negatively charged foreign particles in the hydraulic fluid, there may be particular applications where it is desirable to subject the critical part of the hydraulic system to a potential of constant polarity. For instance if it should be determined that virtually all of the foreign particles in the hydraulic fluid are positively charged, the critical part may be subjected to a positive electrical charge to prevent the accumulation of such particles. Similarly, if it is determined that a particular hydraulic fluid contains only negatively charged foreign particles, the critical part may be subjected to a negative electrical charge to prevent the accumulation of such particles.

This invention may be performed and/or embodied in other ways without departing from the spirit or essential characteristics thereof. The process and embodiments of my invention described herein are therefore to be considered as in all respects illustrative and not restrictive, the scope of my invention being indicated by the appended claims, and all changes which come within the meaning and range of equivalency of the claims are intended to be embraced therein.

The invention claimed is:

1. In a hydraulic system utilizing a dielectric fluid, the improvement comprising:

an electrically conductive valve body connected in said system;

means for electrically insulating said valve body from the other elements of said system; and

means for impressing an electrical potential on said valve body whereby any foreign particles in said fluid having an electrical charge of the same polarity to that impressed on said valve body will be repelled away from said valve body.

2. The apparatus of claim 1 wherein said means for impressing an electrical potential on said valve body is adapted to impress an alternating potential on said valve body.

3. The apparatus of claim 1 including additionally:

a tank connected into said hydraulic system; and

at least one electrode adapted to have a polarity opposite to that of said valve body removably mounted in said tank and adapted to be immersed in said fluid whereby said foreign particles will be collected on said electrode.

4. In a hydraulic system utilizing a dielectric fluid, the

improvement comprising:

an electrically conductive valve body having a valve seat formed internally thereof;

a valve member mounted internally of said valve body having a portion thereof configured to snuggly mate with said valve seat when in a first position and movable to a second position with said portion being withdrawn from contact with said valve seat;

means for electrically insulating said valve seat from a substantial portion of said valve body; and

means for impressing an electrical potential on said valve seat whereby any foreign particle in said fluid having an electrical charge of the same polarity to that impressed on said valve seat will be repelled away from said valve seat.

5. The apparatus of claim 4 wherein said means for impressing an electrical potential on said valve seat is adapted to impress an alternating potential on said valve seat.

6. The apparatus of claim 4 including additionally:

a tank connected into said hydraulic system;

at least one electrode adapted to have a polarity opposite to that of said valve seat removably mounted in said tank and adapted to be immersed in said fluid whereby said foreign particles will be collected on said electrode. 7. In a hydraulic system utilizing a dielectric fluid, the improvement comprising:

an electrically conductive fixed orifice;

means for electrically insulating said orificefrom the other elements of said system; and

means for impressing an electrical potential on said orifice whereby any foreign particles in said fluid having an electrical charge of the same polarity to that impressed on said orifice will be repelled away from said orifice.

8. The apparatus of claim 7 wherein said means for impressing an electrical potential on said orifice is adapted to impress an alternating potential on said orifice.

9. The apparatus of claim 7 including additionally:

a tank connected into said hydraulic system; and

at least one electrode adapted to have a polarity opposite to that of said orifice removably mounted in said tank and adapted to be immersed in said fluid whereby said foreign particles will be collected on said electrode.

References Cited UNITED STATES PATENTS 2,116,509 5/1938 Cottrell 204300 2,336,542. 12/1943 Hatfield 204-188 2,884,375 4/1959 Seelig 204l88 2,870,081 1/1959 Frey 204l84 1,825,477 9/1931 Riechart 204147 2,025,243 12/1935 Jackson et al. 204147 2,077,505 4/1937 W0elflin 204l84 2,376,535 5/1945 Fisher 2041 84 2,665,246 1/1954 Bates 204l84 HOWARD S. WILLIAMS, Primary Examiner.

JOSEPH REBOLD, JOHN R. SPECK, JOHN H. MACK,

Examiners.

E. ZAGARELLA, J. BATTIST, G. KAPLAN,

Assistant Examiners.

Claims (1)

1. IN A HYDRAULIC SYSTEM UTILIZING A DIELECTRIC FLUID, THE IMPROVEMENT COMPRISING: AN ELECTRICALLY CONDUCTIVE VALVE BODY CONNECTED IN SAID SYSTEM; MEANS FOR ELECTRICALLY INSULATING SAID VALVE BODY FROM THE OTHER ELEMENTS OF SAID SYSTEM; AND MEANS FOR IMPRESSING AN ELECTRICAL POTENTIAL ON SAID VALVE BODY WHEREBY ANY FOREIGN PARTICLES IN SAID FLUID HAVING AN ELECTRICAL CHARGE OF THE SAME POLARITY TO THAT IMPRESSED ON SAID VALVE BODY WILL BE REPELLED AWAY FROM SAID VALVE BODY.

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