US3824852A

US3824852A - Electrically powered submerged pump, power circuit therefor, and oceanographic monitoring apparatus and method employing same

Info

Publication number: US3824852A
Application number: US00227075A
Authority: US
Inventors: C Otto
Original assignee: Individual
Current assignee: Individual
Priority date: 1972-02-17
Filing date: 1972-02-17
Publication date: 1974-07-23
Anticipated expiration: 1991-07-23

Abstract

A submerged unit adapted to monitor water conditions several miles from shore, with a housing having a float chamber, a water monitoring section and plurality of reciprocating pumps to move ambient water through the monitoring section. Solenoid type units drive the pumps to move sample water past sensors in the monitoring section and provide inertial masses to vibrate the entire unit both laterally and rotationally to minimize attachment of marine organisms thereto. The power units also provide a constant flushing of screened inlet openings through which the sample water passes so as to prevent clogging thereof by marine organisms or debris. The two power units oscillate 90* out of phase through two sets of two solenoids, one set for each power unit. This is accomplished by circuitry distributing successive half waves of an alternating current supply to the solenoids in sequence. Each solenoid is energized through an electronic valve receiving gated power through another solenoid, the gating being through a capacitor and diode whereby the capacitor is initially rapidly charged and then discharged slowly enough to prevent or block regating until occurrence of a subsequent half wave, the blocking action being reinforced by the voltage drop occurring across the other solenoid, which in the meanwhile has been preferentially gated.

Description

United States Patent Otto [ 51 July 23, 1974 ELECTRICALLY POWERED SUBMERGED PUMP, POWER CIRCUIT THEREFOR, AND OCEANOGRAPHIC MONITORING APPARATUS AND METHOD EMPLOYING SAME [76] Inventor: Carl L. Otto, Lummi Island, Wash.

[22] Filed:' Feb. 17, 1972 [21] Appl. No.: 227,075

[52] US. Cl 73/170 A, 21/54, 21/102, 43/124,134/1, 417/61, 417/62, 417/211 [51] Int. Cl... G016 21/00, B63b 59/00, F04b 17/04 [58] Field of Search.. 73/421, 170; 21/54 A, 102 A, 21/2; 114/222; 9/8 A; 417/61, 62, 211, 313;

[56] References Cited UNITED STATES PATENTS 607,745 7/1898 Hoffman 417/61 2,245,956 6/1941 Baily 43/124 2,561,762 7/1951 Van Toorn 134/1 2,578,673 12/1951 Cushman 21/54 A 3,045,628 7/1962 Waas et a1. 114/40 3,455,144 7/1969 Bradley 73/19 3,661,506 5/1972 Watkins 9/8 Primary Examiner-S. Clement Swisher Attorney, Agent, or Firm-Graybeal, Barnard, Uhlir & Hughes 57 ABSTRACT A submerged unit adapted to monitor water conditions several miles from shore, with a housing having a float chamber, a water monitoring section and plurality of reciprocating pumps to move ambient water through the monitoring section. Solenoid type units drive the pumps to move sample water past sensors in the monitoring section and provide inertial masses to vibrate the entire unit both laterally and rotationally to minimize attachment of marine organisms thereto The power units also provide a constant flushing of screened inlet openings through which the sample water passes so as to prevent clogging thereof by marine organisms or debris.

The two power units oscillate 90 out of phase through two sets of two solenoids, one set for each power unit. This is accomplished by circuitry distributing successive half waves of an alternating current supply to the solenoids in sequence. Each solenoid is energized through an electronic valve receiving gated power through another solenoid, the gating being 43 Claims, 4 Drawing Figures HTENTEDJULZMSN 3.824.852 SIEH 2 BF 2 FIG 3 ELECTRICALLY POWERED SUBMERGED PUMP, POWER CIRCUIT THEREFOR, AND OCEANOGRAPHIC MONITORING APPARATUS AND METHOD EMPLOYING SAME BACKGROUND OF THE INVENTION A. Field of the Invention This invention relates to an oceanographic monitoring unit and method, adapted for use at a remote location, and to components of such unit.

B. Description of the Prior Art In the art of oceanography it is frequently necessary to monitor the conditions of water several miles from shore in locations where it is not feasible to use radio transmission. In such cases a long wire must be laid along the bottom of the body of water being monitored. To save costs this wire must be of light construction, which poses a problem of transmitting sufficient power to the monitoring unit for its proper operation. Further, there are often other problems such as marineorganisms attaching themselves to the unit, and of pump clogging.

A search of the prior art did not disclose any closely related patents in the field of oceanographic monitoring units as such, and the following patents are notable from the point of view of providing general background material.

Nuissl U.S. Pat. No. 3,068,829 discloses a means of cleaning the hull of a ship by means of ultrasonic energy.

Several prior patents disclose various means of clean ing a pump filter by back flushing, such as Zwicky et al U.S. Pat. No. 1,971,090, Kabisch et al U.S. Pat. No. 2,990,238, Hirano et al U.S. Pat. No. 3,ll9,341, and Findlay U.S. Pat. No. 2,855,100.

Patents disclosing various electrical means for operating pumps includeMesh U.S. Pat. No. 2,630,345, Vasilewsky U.S. Pat. No. 2,690,128, Morgan U.S. Pat. No. 3,134,938, Wertheimer et al U.S. Pat. No. 3,381,616, and Rouquette U.S. Pat. No. 3,556,684.

Other patents showing various examples of control circuitry are Fry U.S. Pat. No. 3,129,336, Scott U.S.

Pat. No. 3,316,470, and .Kuschel U.S. Pat. No. 3,400,316.

Melchier U.S. Pat. No. 3,098,389 relates to submarine instrumentation, and discloses a mechanism for determining surface meteorological conditions by a vessel or a station hovering or moving below the surface.

SUMMARY OF THE INVENTION The present invention in part relates to a method of and apparatus especially adapted for monitoring a fluid medium,such as ocean water, in a remote location. Sample fluid is extracted from the ambient fluid and passed through a monitoring section having appropriate sensors. In the preferred embodiment a plurality of reciprocatingpumps operate in sequence to supply a substantially constant stream of sample liquid to the monitoring section. Each of these pumps functions to draw in ambient water through an inlet on a suction stroke, and on a pressure stroke moves some of the liquid to the monitoring section, while passing some of the liquid back out through the inlet to flush the same.

In accordance with another aspect of the present invention, cyclical movements are generated in the surface of the unit relative to the ambient liquid medium at a frequency sufficient to minimize attachment of matter, such as marine organisms, thereto. In the preferred embodiment, this is accomplished by moving an inertial mass in a cyclical path and reacting this mass against the unit so as to produce a combination of lateral and rotational components of movement. Desirably such movement is accomplished by having the center of inertia of the mass offset from the center of inertia of the unit, with the unit arranged to move in a cyclical path having a substantial vectorial component of acceleration spaced from the center of inertia of the unit. Two such inertial masses are provided in the particular unit configuration shown herein, and these reciprocate out of phase so that lateral and rotational components of movement are alternately imparted to the unit. Further, in the preferred embodiment, the action of the inertial masses is utilized to operate the pumps of the unit.

In accordance with another aspect of the present invention, the inertial mass or masses are so arranged relative to the pump or pumps, that the movement of water by the pumping action augments the reacting force of the inertial mass or masses against the unit. In the preferred embodiment, a pair of pumps are arranged oppositely with respect to the inertial mass and are connected thereto so as to operate out of phase, with the result that the alternating action of the pumps cooperatively augments the reacting force of the inertial mass. By arranging two such inertial masses on opposite= sides of the unit, with each mass operating a respective pair of oppositely positioned pumps, and with the inertial masses operating approximately out of phase with one another, the four pumps are caused to operate sequentially, and the inertial masses alternately impart rotational and lateral vectorial components of movement to the unit.

The'circuitry to accomplish this last named function is arranged to distribute successive half-waves of an alternating current supply sequentially through a plurality of actuators for the inertial units. This circuitry comprises a plurality of electronic check valves, each being connected in series with a respective load or actuator so as to pass current only during respective positive or negative half cycles of the alternating current electrical power supplied to the unit. There is an equal number of gating means, each being connected to gate a respective check valve of one actuator and being connected to another of said actuators so as to receive its gating power therefrom. There is also for each gating means a gating delay means, suitably comprising a capacitor and resistor in parallel and a diode in series therewith, the delay means functioning to delay or block operation of a given gating means for at least a succeeding cycle after operation of that gating means on the previous cycle. This is accomplished by discharging a charged capacitor at a rate slow enough to block regating until the arrival of a like subsequent half-wave of power current, and reinforcing the blockage by means of the voltage drop across the other actuator which has been preferentially gated by reason of the unblockage of its gating circuit.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an isometric view of an oceanographic monitoring unit typical of the present invention, with portions thereof cut away;

FIG. 2 is an isometric view of one of the power units of the unit shown in FIG. 1;

FIG. 3 is a vertical sectional view taken through the lower forward portion of the unit shown in FIG. 1; and

FIG. 4 is a diagram of the power and control circuitry employed in the unit shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT The oceanographic monitoring unit l comprises a shell-like housing 12 which has therein an upper toroidal float chamber 14, a main water collecting chamber 16 and four

pumping chambers

18a, 18b, 18c and 18d, respectively arranged in two sets spaced oppositely from one another in the lower portion of the housing 12. In the lower portion of the chamber 16 are two power units 20 which perform three main functions. The first such function is the supply of power to cause water to be pumped through the pumping chambers 18 into the main collecting chamber 16 and out through an upper outlet passageway 22 located in the center of the toroidal float chamber 14 so as to provide sample water by which the monitoring function is accomplished. The second function is the provision for constant flushing of screened inlet openings (to be described hereinafter) through which sample water is taken into the pumping chambers 18. The third function is the cyclic vibration of the entire unit in a manner to minimize attachment of material such as marine organisms thereto. v i

The housing 10 comprises a cylindrical side wall 24, a bottom wall 26 formed integrally therewith, and a removable circular cover 28, with the external surface of the housing 12 being substantially a surface of revolution about a vertical center axis. The float chamber 14 is defined by a cover 28 and a generally toroidal wall 30 having a substantially U-shaped cross section. The cover 28 has a center hole 32 enabling outflow of water through the aforementioned outlet passageway 22. One set of

adjacent pumping chambers

18a and 18b is formed by a respective horizontal top wall 34 shaped as a segment of a circle, a vertical side wall 36, a partition wall 38 separating the two

chambers

18a and 18b, and an adjacent portion of the housing 12. The two

other pumping chambers

18c and 18d are formed by like walls on the opposite side of the housing 12.

Inlet openings for each of the pumping chambers 18 are formed as a plurality of screened apertures 40 in the housing 12. These apertures 40 are conveniently formed by providing a patch 42 closely fitted and fastened to the interior surface of the housing 12. Holes are drilled through the assembled outer housing 12 and patch 42. The patch is then removed and replaced, with a fine screen 44 inserted between the outer housing 12 and patch 42. v Each of the

pumping chambers

18a, 18b, 18c, 18d has as an outlet a check valve 46 formed in its related top wall 34. In the particular configuration shown herein each such valve 46 comprises a comb-shaped leaf spring 48, having a plurality of fingers 50 fitting over holes 52 in the top wall 34. These fingers 50 are sufficiently light and flexible to allow the escape of the required amount of water through the valve holes or openings 52.

Each pumping chamber 18 comprises a stiff pumping diaphragm or piston 54 located in the related pumping chamber side wall 36. Each pair of oppositely disposed pumping diaphragms 54 is actuated by a respective one of the two aforementioned power units 20. Each power unit 20 comprises a pair of solenoids, S1 and S2 being one set and S3 and S4 being the other, with S3 and S4 being shown only in FIG. 4. Each solenoid is attached to a respective diaphragm 54. Each solenoid pair (i.e., S1 and S2 on the one hand and S3 and $4 on the other hand) is arranged in line and each pair is joined rigidly to one another by rails 58 so that the diaphragms 54 of opposing pumping chambers (18a and 18c being one opposed set and 18b and 18d being the other) are by these means tied together, with one

pumping chamber

18a or 18b, respectively, having positive displacement while its opposing

pumping chamber

18c or 18d, respectively, has negative displacement. The plungers 60 of the solenoids S1 through S4 are fixed to the housing 10 by being fastened to a center plate 62 which is rigidly connected to the power unithousing 64, which is in turn fixedly attached to the main housing 12 through the pump housing side wall 36.

As will'be disclosed more fully hereinafter, the power units 20 cause cyclical movement or vibration of the unit 10. In order to increase the total moving mass which causes the vibration, each of the housings 64-is filled with oil, a fill plug 66 being conveniently provided for this purpose. Holes 68 are provided in the center plate 62-that partitionsthe housing 64 to provide for the passage of oil from one chamber 70 to the other chamber 72 in the housing 64 of each of the power units 20. Also holes 74 are placed in the side wall of the housing 64 and sealed with a flexible band of material 76, partly for purpose of expansion relief and partly to facilitate the exchange of displaced fluid.

Each of the diaphragms 54 is rigid and acts like the I head of a piston having an amplitude of stroke, typically, of l millimeter. Flexibility sufficient to permit this motion is provided by a flexible washer 78 which is attached to the diaphragm 54 by means of a clamping ring 80 and to the housing 64 by a clamping ring 82.

Mounted within the float chamber 14, so as to be in a protected and dry location, is a sensory circuit block 84 which can be considered the payload" of the unit 10. While only one such block 84 is shown herein, there could be other such blocks in the chamber 14. The block 84 is provided with a sensor 86 which projects into the stream of sample fluid passing through the passageway 22. The sensor 86 is connected to its associated block 84 by means of a wire passing through a sealed aperture in the wall 30.

Power cable 90 delivers input power for the unit 10 and also provides outlet leads for the one or more sensory circuit blocks 84. The cable 90 suitably enters the unit 10 through an aperture located in the center of the bottom wall 26 of the housing 12. Typically, the unit 10 has a net excess of buoyancy and in such case the cable 90 also acts as a tether securing the unit 10 to an anchoring unit (not shown). Such an anchoring unit'may contain heavy components such as a transformer (to be described hereinafter with reference to FIG. 4) and possibly a motor for reeling out and reeling in cable 90 to raise and lower the monitoring unit 10. The aperture for the cable 90 need not be sealed because the main chamber 16 of the housing 12 contains the same fluid as found outside the housing 12, and at substantially the same pressure.

The cable 90 passes upwardly through the center of the main chamber 16 and enters the float chamber 14 through a sealed aperture in the toroidal wall 30. The various wires of this cable 90 then connect to the one or more sensory blocks 84 andto another circuit block 96 by which the four solenoids S1 through S4 are sequentially activated (as will be described hereinafter with reference to FIG. 4).

in disclosing the operation of the monitoring unit 10, the following description is directed to the pumping and flushing action of a single pumping chamber 18 and its associated components, these comprising a single pumping unit. The description is then directed to the action of the power units 20 and the sequencing of such action, which action is the source of movement of the inertial masses in the unit to cause its vibration so as to minimize attachment of marine organisms to the unit. The circuitry by which the four solenoids S1 through S4 are sequentially activated to cause such sequential action is then described.

A single pumping unit comprises a single pumping chamber 18, with its respective inlet apertures 40, outlet valve 46, pumping diaphragm 54 and its related solenoid S1, S2, S3 or S4. On the intake stroke (i.e., suction stroke) of the diaphragm 54, ambient water is drawn into the chamber 18 through the inlet openings 40, with the valve 46 remaining closed because of the negative pressure causing the leaf spring 48 to close the valve holes 52. On the exhaust stroke (i.e., pressure stroke) of the diaphragm 54, water in the chamber 18 is pushed back out through the inlet apertures 40 so as to flush the screens 44 in the apertures 40. The screened apertures 40 are proportioned, in terms of their total area and of the pore size of the screens, so as to offer sufficient resistance to passage of water therethrough to retain pressure within the chamber 18 for lifting the leaf spring 48 of the valve 46 and cause some of the water in the chamber 18 to pass through the valve 46 into the main collecting chamber 16. Typically, about 90 percent of the water discharged from the chamber 18 passes back through the apertures 40 while the remaining 10 percent passes through the valve 46 into the main chamber 16 and serves as the sample fluid to be monitored.

To describe the action of the power units 20 with respect to the other components of the unit 10, it is first to be noted that each pair of solenoids S1, S2 and S3, S4 in a respective one of the power units 20 is positioned in line with one another and oscillates along the same axis. This axis of oscillation is offset from the .vertical center axis of the unit 10, and is in a plane perpendicular to the vertical center axis of the unit 10, so that there is a cyclical movement of each connected set of solenoids, such movement having a substantial vectorial component of acceleration offset from the vertical center axis of the unit 10, which is also the vertical center axis of the housing 12. Further, since the two connected solenoids in a single power unit 20 are fixedly connected one to another by rails 58, the two diaphragms 54 of one power unit 20 (being positioned oppositely with respect to one another) move together, with one diaphragm 54 having positive displacement on its pressure stroke, while the opposing diaphragm 54 at the same time has negative displacement on its suction stroke.

During one stroke of a given pair of connected solenoids S1, S2 or S3, S4, the associated diaphragms 54 cause a lateral movement of the fluid in the power housing 64 in the same direction as the solenoids. Likewise, a portion of the water mass in one

chamber

18a or 18b is pushed outwardly through the apertures 40 while a portion of the water mass is drawn into its respective opposing chamber or 18d, with the water in these two chambers moving in the same direction as their related solenoids. Thus the total inertial mass causing vibration of the unit 10 on a given stroke is the solenoid pair S1, S2 or the pair S3, S4 (along with any structure attached thereto), the fluid in the housing 64,

and the water in its respective pair of

opposed chambers

18a, 180 or 1812, 18d.

Solenoids S1 through S4 are activated in the following sequence: S1, S3, S2, S4, and so on continuously. Thus, three is first a movement of the interconnected solenoids S1, S2 to the left (with reference to the view in FIG. 1), then a movement of the interconnected solenoids S3, S4 to the left also, then a movement of the interconnected solenoids S1, S2 tothe right, followed by a movement of solenoids S3, S4 to the right with this sequence being repeated continuously. Since the total inertial mass associated with each interconnected solenoid pair S1-S2, or S3-S4, is offset from the vertical center axis of the unit 10, and since the vertical center axis of the unit 10 is substantially coincident with the center of inertia of the unit 10, the movement of each interconnected set of solenoids (having a substantial vectorial component of acceleration spaced from the center of inertia of the unit 10) causes a net reaction which is a combination of rotational movement of the unit 10 as well as a lateral or translating movement. Thus there is a movement vector perpendicular to the housing surface and a movement vector parallel to the housing surface. The effect of this rotational and lateral vibrating action of the unit 10 is to produce both momentary pressure changes and movement in shear with respect to the surrounding liquid, at a frequency (eg 30 Hz) minimizing the adherence of small marine organisms to the unit 10.

The circuitry by which sequential activation of the four solenoids 56 is accomplished is shown in FIG. 4. Transformer T serves as a source of alternating current power (at 60 Hz, for example) for actuation of the solenoids S1-S4. Solenoids S1 and S2 are connected to a first side of the transformer T through a capacitor C5, and are each connected to the second side of the transformer in series with a respective one of two electronic valve devices, suitably silicon-controlled rectifiers SCRl and SCR2. Solenoids S1 and S2 are thus energized only during the positive half cycles of the AC voltage across the secondary of transformer T.

Solenoid S1 is connected through parallel connected capacitor C2 and resistor R2 and series connected diode D2 to trigger the gating means of the siliconcontrolled rectifier SCRZ in series with the other solenoid S2. Likewise, the solenoid S2 is connected through parallel connected capacitor C1 and resistor R1 and series connected diode D1 to trigger the gating means of the silicon-controlled rectifier SCRl.

The solenoids S3 and S4 are connected directly to the second side of the transformer T and are connected through respective silicon-controlled rectifiers SCR3 and SCR4 and capacitor C5 to the first side of the secondary of transformer T so as to be able to respond only on negative half cycles of the AC voltage across the secondary of transformer T. As with rectifiers SCRl and SCR2, there are similar components to trigger each of the silicon-controlled rectifiers SCR3 and SCR4, namely, a respective capacitor C3 or C4, resistor R3 or R4, and diode D3 or D4, arranged similarly to corresponding components C1 and C2, R1 and R2, and D1 and D2.

Respective resistors R5, R6, R7, R8 provide load paths forthe respective triggering circuit diodes D1, D2, D3 and D4, and respective parallel connected diodes D5, D6, D7 and D8 across the resistors R5, R6, R7 and R8 are optionally provided to suppress transient spikes.

In a typical circuit, as schematically shown at FIG. 4, wherein the secondary of transformer T delivers 60 Hz power at 20 volts R.M.S. the following component values and types are employed:

I megohm R-R8 22 K. ohms Cl-4 0.02 mfd .C5 70 mfd Dl-4 lN458 D5-8 lN456 SCRl-SCR4 Motorola Model No. MCR 406-4 Sl-S4 Dormeyer Industries Model No. 2786-M-l,

modified To improve the action and response of the solenoids Sl S4, the particular solenoid model indicated was modified in a prototype unit by removing the shading rings and doubling the number of residual springs, to more rapidly and more reliably break the residual magnetism of the core, i.e., to unstick the plunger. In addition, for the same purpose, epoxy soaked paper strips were adhered to the solenoid pole pieces to provide a minimum gap of about .OOS'inch.

To describe the operation of the circuitry of FIG. 4, let it be assumed that S1 is in the process of being pulsed by the positive half of the power wave from transformer T and that S2 is being blocked. The positive power wave acting through the capacitor C1 and diode D1 has just activated the trigger of SCRl causing a power pulse to energize the solenoid S1. Through the rising part of the half wave, capacitor.C1 continues passing current through the trigger of SCRl by way of diode D1. This has the incidental effect of charging capacitor C1 substantially to the peak voltage of the power wave. When the peak voltage is reached, diode D1 prevents a reversal of the charge in capacitor C1, which charge discharges through the resistor R1 at a rate determined by the R1Cl time constant. In this case the time constant is selected to complete, essentially, the discharge of capacitor C1 by the time the second following positive half wave of T1 voltage occurs. During the first positive half wave, it has been assumed that the solenoid S2 is not pulsing but is carrying the triggering current for SCRl, which, however, will not be strong enough in terms of current flow to activate solenoid S2 or to result in an appreciable voltage drop across it. 7

During the negative half wave, the Sl-S 2 complex remains inactive. SCRl and SCR2 are both quiescent, and diodes D1 and D2 prevent activity in the triggering network; however, Cl is still discharging through resistance R1. At the next following positive half wave, again, both SCRl and SCR2 might be expected to fire; however the capacitor C1 is still partly charged, presenting a negative charge to the trigger of SCR1. The inhibiting effect of this remnant charge causes a lag in the triggering response of SCRl which cannot be overcome by the power wave until the wave has progressed fairly well into its positive half cycle. The triggering network of SCR2 has no such blockage and, therefore, SCR2 fires at the beginning of this positive half wave. This has the effect of creating a large voltage drop across solenoid S2, essentially bringing the input of the triggering network of SCRl to a condition of not being powered. Since this takes place at the beginning of the positive half wave while SCRl is being inhibited from firing, SCRl does not fire during this entire positive half cycle of the power wave. This condition repeats the condition existing at the point of beginning of the sequential explanation, and the pulsing of the solenoids S1 and S2 will continue on alternate halves of the positive power wave as long as the power is supplied. The same operating sequence applies to solenoids S3 and S4, with polarity reversed, sothat solenoids S3 and S4 are energized alternately on the negative half wave of the supplied power.

Capacitor C5, in series with the power supply, is for the purpose of power factor adjustment, neutralizing the' inductive effect of the solenoid windings, thus markedly improving the power efficiency.

The value of capacitor C5 is selected to establish an essentially series resonance condition with the inductance of whichever load circuit comprises an energized solenoid, i.e. capacitor C5 is nominally in circuit with only one solenoid at a time, with each of the four solenoids S1-S4 energized sequentially and in such a way that the normal energy transfer is essentially a series resonance condition, with its attendant power efficiency. With a series resonance condition the power consumption in the circuit is only about 10 percent of the power which would be required if the pump drive were by conventional rotary motor means, i.e., about 20 watts as compared with about 200 watts for a like amount of water pumped and for energy utilization to flush the inlet screens and vibrate the unit. In selecting an appropriate value for capacitor C5 in a particular installation, the inductive effect of the secondary of transformer T can be considered negligible and the mean value of the inductance of each solenoid S is to be determined. In the instance of the component values set forth above as illustrative, each solenoid 81-54 has a mean value of about 0.1 henry, it being also notable with respect to the inductance of the solenoid S that the instantaneous inductance changes sharply with change in position of the core or plunger, so that mean value is best determined on.the basis of the average inductance of the solenoid throughout its period of energization.

Capacitor C5 also serves the important function of blocking DC current flow in the secondary of transformer T; if C5 were not in the circuit the transformer T might otherwise become saturated and solenoids 81-84 would not be sequentially energized for essentially equal periods as desired.

As described previously herein, the sequential energization of the solenoids Sl-S4 introduces a rotational component to the mechanical vibration of the measuring unit. Solenoids S1 and S2 are paired in one power unit 20 and pulsed as explained above, in alternate half waves. This amounts, in the case of a 60 Hz power supply, to a vibration rate of 30 Hz. Solenoids S3 and S4 are paired in the other power unit 20 and also pulsed at 30 Hz but in a different phase relationship,

displaced from the vibration of the first power unit 20. The net vectorial reaction of the combination is a mixture of translation and rotation of the housing 12 of the monitoring unit. As disclosed previously herein, this vibration of the outerhousing 12 causes both momentary pressure changes and movement in shear with respect to the surrounding liquid, tending to markedly minimize the attachment-of larvae of marine organisms to the outer surface of housing 12. At the same time, as disclosed previously, the vibrational movement of the solenoids produces a pumping action and a flushing of the inlet screens as described before.

Actual tests of a prototype unit submerged in salt water in Puget Sound over a period of several months has shown that the unit has only about 10 percent marine growth accumulation on the surface of the unit, as compared with the extent of marine growth on nonvibrated surfaces under like conditions. It is surmised that if the unit tested had been provided with Teflon surfaces it would likely have been completelylfree of adherent marine growth. During such testing, the screens of the unit flushed quite well but were not completely clear, and in this respect it is surmised that a realistic maintenance program would contemplate bringing the units to the surface for inspection and cleaning periodically, e.g., about once a year, for example.

The sequencing at a 30 Hz rate using 60 Hz power has the further advantage of introducing an interval between the powering of opposing members of the paired solenoid combination. This interval prevents oppositional power overlap which would otherwise be caused by the lagging inductive current, enabling the electric current caused by the collapse of the magnetic fields of the solenoids to be returned to the power supply during a period of mechanical non-opposition, thus increasing the power efficiency. g

The described combination of methods and apparatus for the protection 'of sensors and provision of a steady stream of filtered sample fluid therefor, provides a monitoring unit capable of maintaining accurate measurement over long periods of unattended operation and at long distances from shore through a lightly constructed, inexpensive wire connection.

In addition to the disclosed utility of the solenoid type pumping units and control circuitry for oceanographic monitoring purposes as above discussed, it will be apparent that pumping units and control circuitry of this type also have utility to function as the pumping means for a fresh water supply system, submerged in a well or the like. In such event, the backflushing feature can be eliminated, the four solenoid pump units are each provided with an inlet valve and are operated in series to increase pumping pressure, and the solenoid units need not necessarily be mounted in pairs, but can be mounted individually and each provided with a spring return in a manner conventional per se. With respect to the application of this type of unit to the pumping of fresh water in the domestic or industrial water supply field, it is to be noted that while solenoid actuated pump means heretofore have been considered impractical in this field because of relatively low power efficiency, the use of a series resonant power circuit (c.f. capacitance C) renders this type of pumping mechanism practical from the power efficiency point of view and the inherent simplicity, reliability and long life of such a unit offers very substantial advantages over conventional rotary motor pumped units for the purpose.

Another potential usage of solenoid powered units with similar control circuitry is in the field of mechanical vibrators, such as used in vibration type particulate material handling systems, where solenoid type vibrator units can provide an efficient vibration source. In such a unit, the vibration frequency can be at line frequency or'a sub-multiple of line frequency, or can be made variable as by providing a variable frequency power input and a variable series resonant capacitance so that the vibration frequency of the unit can be adjusted to coincide with the fundamental or a multiple or submultiple of the natural vibration frequency of the equipment vibrated. 1

As will be apparent, the control circuitry of the present invention can readily be designed to involve any even number of solenoid pump units, such as by incorporation of six solenoid units with each operated every third positive (or negative) half-cycle of the power input frequency, or 'such as by utilizing eight solenoid units with each operated every fourth positive (or negative) half cycle.

What is claimed is:

1. A method of minimizing attachment of marine organisms or the like in an aqueous medium to an exposed surface of a body submerged in the medium, comprising: moving said body in cyclical movements in said aqueous medium to produce relative cyclical movement of said surface relative to said aqueous medium, at a frequency sufficient to minimize attachment of said matter thereto, said cyclical movement being accomplished by:

a. cyclically accelerating an inertial mass in cyclical fashion in a path having a substantial reciprocating .vec torial component to produce a corresponding reciprocating component of movement in said body,

b. reacting said inertial mass against said body, to

cause said cyclical movements of said body relative A to said aqueous medium,

c. further comprising accelerating said mass in a cyclical path having a substantial vectorial component of acceleration spaced from a center of inertia of the body, whereby a cyclical rotational vectorial component is imparted to said body, wherein said body and said inertial mass each has a center of inertia spaced from one another.

2. The methodas recited in claim 1, comprising accelerating in cyclical fashion a second inertial mass having a center of inertia spaced from the center of inertia of said body, and reacting said second inertial mass against said body.

3. The method as recited in claim 2, wherein said second inertial mass is accelerated out of phase with respect to said first named inertial mass in a manner that alternating rotational vectorial components are imparted to said body.

4. The method as recited in claim 1, further comprising accelerating a second inertial mass in cyclical fashion and reacting said second inertial mass against said body, said second inertial mass being accelerated out of phase with respect to said first named inertial mass, whereby alternating cyclical movement vectors are imparted to said body.

5. A method of pumping a liquid, such as water relative to a unit, such as an oceanographic monitoring unit, by means of a reciprocating pump means having inlet and outlet valve means, while preventing attachment of matter, such as marine organisms, to an exposed surface of said unit in contact with said liquid, said method comprising:

a. accelerating an inertial mass in a predetermined cyclical path having a substantial reciprocating vectorial component,

b. reacting said mass against said unit so as to apply a cyclic force therebetween, thereby causing cyclic acceleration of said surface relative to said liquid and of said mass in a direction having a substantial vectorial component of travel opposite to that of said unit, and

c. operatively coacting 'said inertial mass as'a piston with said pump means so as to cause pumping of said liquid into said valve inlet means and out of said valve outlet means.

6. The method as recited in claim 5, wherein said body and said inertial mass each has a center of inertia spaced from one another, further comprising moving said mass in a cyclical path having a substantial vectorial component spaced from the center of inertia of the body, whereby a cyclical rotational vectorial component is imparted to said body.

7. The method as recited in claim 6, comprising accelerating in cyclical fashion a second inertial mass having a center of inertia spaced from the center of inertia of said body, and reacting said second inertial mass against said body.

8. The method as recited in claim 7, further comprising operatively coacting said second inertial mass with second pump means so as to cause pumping of said liquid relative to said unit.

9. The method as recited in claim 7, wherein said second inertial mass is accelerated out of phase with respect to said first named inertial mass in a manner that alternating rotational vectorial components are imparted to said body. i

10. The method as recited in claim 5, further comprising accelerating a second inertial mass in cyclical fashion and reacting said second inertial mass against said body, said second inertial mass being accelerated out of phase with respect to said first named inertial mass, whereby alternating cyclical movement vectors are imparted to said body in different directions.

11. The method as recited in claim 5, wherein the cyclical acceleration of the inertial mass is such as to have a substantial reciprocating vectorial component, and further comprising reciprocating a pumping piston to draw liquid in through an inlet and to discharge liquid through an outlet.

12. The method as recited in claim 11, further comprising cyclically discharging liquid also through said inlet by means of said pumping piston so as to flush said inlet.

13. The method as recited in claim 12, further comprising moving said liquid toward and from said inlet in a direction having a vectorial component paralleling said reciprocating vectorial component of the inertial mass so as to augment the reacting of the inertial mass against said unit.

14. The method as recited in claim 11, further comprising accelerating in a cyclical fashion a second inertial mass along a path having a substantial reciprocating vectorial component to reciprocate a second pumping piston, and reacting said second inertial mass against said unit so as to cause cyclical movement of said unit.

15. The method as recited in claim 14, wherein said second inertial mass is accelerated out of phase with said first named inertial mass so as to impart alternating increments of movement to said unit.

16. An apparatus adapted to monitor a liquid medium, such as an aqueous medium, said apparatus comprising:

a. a housing having an exposed surface adapted to be in contact with said liquid medium,

b. pump means arranged to pump said liquid medium,

c. an inertial mass arranged to move in a predetermined cyclical path with respect to said housing,

d. means to move said inertial mass in said cyclical path,

e. means-to react said inertial mass against said housing to cause cyclical. movement of said housing in a manner that there-is cyclical movement of said surface relative to said liquid, and

f. means operatively connecting said inertial mass with said pump means in a manner that movement of said inertial mass causes operation of said pump means.

17. The apparatus as recited in claim 16, wherein said inertial mass is arranged to move in a cyclical path having a substantial reciprocating vectorial component of acceleration.

18. The apparatus as recited in claim 16, wherein both said inertial mass and said housing have respective centers of inertia spaced from one another, and said inertial mass is arranged to move in a cyclical path having a substantial vector of acceleration spaced from the center of inertia of' the housing, whereby a rotational cyclical component of movement is imparted to said housing.

19. The apparatus as recited in claim 18, wherein said inertial mass is arranged also to move in its cyclical path with a substantial reciprocating vectorial component of acceleration, whereby said housing has a reciprocating vectorial component of movement.

20. The apparatus as recited in claim 16, wherein said housing has an exposed surface generally configured as a surface of revolution about a center axis, said inertial mass having a center of inertia spaced from said center axis, and said inertial mass being arranged to have a substantial vectorial component of acceleration spaced from said center axis and in a plane perpendicular to said center axis, whereby a rotational oscillating component of movement generally about said center axis is imparted to said housing.

21 The apparatus as recited in claim 20, wherein there is a second inertial mass having a center of inertia spaced from said center axis, said second inertial mass being arranged to have a substantial vectorial component of acceleration spaced from said center axis and in a plane perpendicular to said center axis, whereby a second rotational oscillating component of movement is imparted to said housing.

22. The apparatus as recited in claim 21, wherein there is means to move said second inertial mass out of phase with saidfirst inertial mass so that alternating components of movement are imparted to said housing.

23. The apparatus as recited in claim 23, wherein said pump means comprises:

a. means defining a pumping chamber,

b. piston means arranged to move in a reciprocating fashion relative to said chamber so as to have a suction stroke and a pressure stroke,

c. inlet means for said chamber to permit inflow of said liquid medium on said suction stroke,

d. outlet means for said chamber to permit outflow of said liquid medium on said pressure stroke,and

e. said inlet and outlet means being arranged relative to said piston and said chamber to provide an outflow of liquid medium back through said inlet means on said pressure-stroke.

24. The apparatus as recited in claim 23, wherein said inertial mass has a substantial reciprocating vectorial component, and said pump means is arranged relative to said inertial mass to provide that action of said piston moving said liquid medium by virtue of the reciprocating motion of the piston causes reciprocating accelerating motion of said liquid medium on a path having a substantial vectorial component paralleling that of said inertial mass, whereby reaction of the inertial mass against the housing is augmented by the liquid medium. v r t 25. The apparatus as recited in claim 24, wherein there is a second pump means arranged with piston means, inlet means and outlet means generally functionally similar to said first named pump means and arranged oppositely thereto, said second pump means also being arranged to be operated by movement of said inertial mass in generally opposite phase relationship to said first pump means, whereby movement of said liquid medium by said second pump means further augments'the reaction of the .inertial mass against the housing.

26. The apparatus'as recited in claim 25, wherein the piston means of said first and second pump means are connectedto opposite sides of said inertial mass so as to reciprocate on their suction and pressure strokes in opposite phase relationship. v

27. The apparatus as recited in claim 25, wherein there is a second inertial mass having third and fourth pump means, each with piston means, inlet means and outlet means functioning generally similarly to said first and second pump means, said second inertial mass being arranged to reciprocate out of phase with respect to said first inertial mass, whereby alternating cyclical movement components are'imparted to said housing.

28. The apparatus as recited in claim 16, said apparatus further comprising a liquid monitoring section, and said pump means being arranged to draw in ambient liquid and deliver said liquid to said monitoring section.

29. The apparatus as recited in claim 28, wherein there is a plurality of pump means arranged to function in alternating relationship to direct ambient liquid to said monitoring section, whereby a substantially constant stream of liquid is directed to said monitoring secb. a monitoring section in said housing adapted to receive and discharge sample water of said ambient d. a plurality of pump means adapted to draw in am- I bient water and to direct sample water therefrom to said monitoring section, said pump means arranged to function in alternating relationship to direct ambient liquid to said monitoring section,

whereby a substantially constant stream of liquid is directed to said monitoring section, each of said pump means comprising:

1. means defining a pumping chamber,

2. piston means arranged to move in a reciprocating fashion relative to said chamber so as to have a suction stroke and a pressure stroke,

3. inlet means for said chamber to permit inflow of said liquid medium on said suction stroke,

4. outlet means for said chamber to permit outflow of said liquid medium on said pressure stroke, and

5. said inlet and outlet means being arranged relative to said piston and said chamber so that there is an outflow of liquid medium back through said inlet means on said pressure stroke.

32. The apparatus as recited in claim 31, wherein there is wall means defining a float chamber, sensor responsive means in said float chamber isolated from said liquid, and sensor means arranged to be in operative contact with sample liquid at said'monitoring section.

33. In a body adapted to function in an aqueous liquid, such as ocean water, and having an exposed surface adapted to be in contact with said liquid, apparatus to prevent attachment of matter, such as marine organisms, to said surface, said apparatus comprising:

a. an inertial mass arranged to move in a predetermined cyclical path with respect to said body, said inertial mass being so arranged that said cyclical path has a substantial reciprocating vectorial component of acceleration, whereby a corresponding reciprocating component of acceleration is imparted to said body,

b. means to react said inertial mass against said body to cause corresponding cyclical movement of said body,

0. means to move said inertial mass in said cyclical path at a frequency sufficient to minimize attachment of said matter to said body, and

d. said body and said mass each having a center of inertia spaced from one another, and said mass being so arranged that its vectorial component of acceleration is spaced from the center of inertia of the body, whereby a cyclical rotational vectorial component is imparted to said body.

34. The apparatus as recited in claim 33, wherein there is: l

a. a second inertial mass having a center of inertia spaced from the center of inertia of the body and arranged to move on a predetermined cyclical path with respect to said body,

b. second reacting means to react said second inertial mass against said body to cause cyclical movement of said body, and c. second moving means to move said second inertial mass in its cyclical path.

35. The apparatus as recited in claim 34, wherein said second moving means is arranged to move said second inertial mass out of phase with said first inertial mass to impart alternating rotational vectorial components to said body. I

36. The apparatus as recited in claim 35, wherein said first moving means comprises first and second electrically responsive generally oppositely acting actuators and said second moving means comprises third and fourth electrically responsive generally oppositely acting actuators, circuit means arranged to energize said actuators in sequence as follows: first said first actuator, secondly said third actuator, thirdly said second actuator, and fourthly said fourth actuator.

37. The apparatus as recited in claim 36, wherein said circuit means comprises:

a. a plurality of electronic check valve means, each being connected in series with a respective actuator and connected therewith across a source of alternating current so that each check valve means passes current only during one set of either positive I or negative half cycles of the alternatingcurrent,

b. a plurality of gating means, each being connected to gate a respective check valve of one actuator,

and being operatively connected with another of said actuators so as to receive its gating power therefrom, and

c. a plurality of gating delay means, each operatively connected to a respective gating means and arranged todelay operation thereof for at least a succeeding half cycle of the half cycle set on which its gating means operates after operation of its gating means on a previous half cycle of the half cycle set on which it operates.

38. The apparatus as recited in claim 37, wherein at least one of said gating delay means comprises capacitor means and means to leak a charge from said capacitor in a predetermined length of time.

39. The apparatus as recited in claim 37, wherein at least one of said gating delay means comprises capacitor means and resistance means connected in parallel.

40. The apparatus as recited in claim 39, comprising 16 a diode connected in series with each of said gating delay means.

41. The apparatus as recited in claim 37, wherein each of said electronic check valve means comprises a silicon controlled rectifier.

42. The apparatus as recited in claim 37, wherein:

a. each of said gated electronic check valve means comprises a silicon controlled rectifier means, and

b. each of said gating delay means comprises a capacitance means and resistance means in parallel and diode means in series therewith, whereby the-capacitancemeans is charged during the gating opera. a plurality of second check valve means, each being connected in series with a respective actuator across a source of alternating current to pass current only on the other set of either positive or negativehalf cycles of the alternating current, a plurality of second gating means, each being connected to gate a respective one of said second check valve means of one actuator, and being connected with another of said actuators to receive its gating power therefrom, and c. a plurality of second gating delay means, each being operatively connected to a respective one of said second gating means and arranged to delay operation thereof for at least a succeeding half cycle of said other half cycle set after operation of the related second gating means on a previous half cycle of said other half cycle set.

Claims

1. A method of minimizing attachment of marine organisms or the like in an aqueous medium to an exposed surface of a body submerged in the medium, comprising: moving said body in cyclical movements in said aqueous medium to produce relative cyclical movement of said surface relative to said aqueous medium, at a frequency sufficient to minimize attachment of said matter thereto, said cyclical movement being accomplished by: a. cyclically accelerating an inertial mass in cyclical fashion in a path having a substantial reciprocating vectorial component to produce a corresponding reciprocating component of movement in said body, b. reacting said inertial mass against said body, to cause said cyclical movements of said body relative to said aqueous medium, c. further comprising accelerating said mass in a cyclical path having a substantial vectorial component of acceleration spaced from a center of inertia of the body, whereby a cyclical rotational vectorial component is imparted to said body, wherein said body and said inertial mass each has a center of inertia spaced from one another.

2. The method as recited in claim 1, comprising accelerating in cyclical fashion a second inertial mass having a center of inertia spaced from the center of inertia of said body, and reacting said second inertial mass against said body.

5. A method of pumping a liquid, such as water relative to a unit, such as an oceanographic monitoring unit, by means of a reciprocating pump means having inlet and outlet valve means, while preventing attachment of matter, such as marine organisms, to an exposed surface of said unit in contact with said liquid, said method comprising: a. accelerating an inertial mass in a predetermined cyclical path having a substantial reciprocating vectorial component, b. reacting said mass against said unit so as to apply a cyclic force therebetween, thereby causing cyclic acceleration of said surface relative to said liquid and of said mass in a direction having a substantial vectorial component of travel opposite to that of said unit, and c. operatively coacting said inertial mass as a piston with said pump means so as to cause pumping of said liquid into said valve inlet means and out of said valve outlet means.

9. The method as recited in claim 7, wherein said second inertial mass is accelerated out of phase with respect to said first named inertial mass in a manner that alternating rotational vectorial components are imparted to said body.

16. An apparatus adapTed to monitor a liquid medium, such as an aqueous medium, said apparatus comprising: a. a housing having an exposed surface adapted to be in contact with said liquid medium, b. pump means arranged to pump said liquid medium, c. an inertial mass arranged to move in a predetermined cyclical path with respect to said housing, d. means to move said inertial mass in said cyclical path, e. means to react said inertial mass against said housing to cause cyclical movement of said housing in a manner that there is cyclical movement of said surface relative to said liquid, and f. means operatively connecting said inertial mass with said pump means in a manner that movement of said inertial mass causes operation of said pump means.

18. The apparatus as recited in claim 16, wherein both said inertial mass and said housing have respective centers of inertia spaced from one another, and said inertial mass is arranged to move in a cyclical path having a substantial vector of acceleration spaced from the center of inertia of the housing, whereby a rotational cyclical component of movement is imparted to said housing.

20. The apparatus as recited in claim 16, wherein said housing has an exposed surface generally configured as a surface of revolution about a center axis, said inertial mass having a center of inertia spaced from said center axis, and said inertial mass being arranged to have a substantial vectorial component of acceleration spaced from said center axis and in a plane perpendicular to said center axis, whereby a rotational oscillating component of movement generally about said center axis is imparted to said housing. 21 The apparatus as recited in claim 20, wherein there is a second inertial mass having a center of inertia spaced from said center axis, said second inertial mass being arranged to have a substantial vectorial component of acceleration spaced from said center axis and in a plane perpendicular to said center axis, whereby a second rotational oscillating component of movement is imparted to said housing.

22. The apparatus as recited in claim 21, wherein there is means to move said second inertial mass out of phase with said first inertial mass so that alternating components of movement are imparted to said housing.

23. The apparatus as recited in claim 23, wherein said pump means comprises: a. means defining a pumping chamber, b. piston means arranged to move in a reciprocating fashion relative to said chamber so as to have a suction stroke and a pressure stroke, c. inlet means for said chamber to permit inflow of said liquid medium on said suction stroke, d. outlet means for said chamber to permit outflow of said liquid medium on said pressure stroke, and e. said inlet and outlet means being arranged relative to said piston and said chamber to provide an outflow of liquid medium back through said inlet means on said pressure stroke.

24. The apparatus as recited in claim 23, wherein said inertial mass has a substantial reciprocating vectorial component, and said pump means is arranged relative to said inertial mass to provide that action of said piston moving said liquid medium by virtue of the reciprocating motion of the piston causes reciprocating accelerating motion of said liquid medium on a path having a substantial vectorial component paralleling that of said inertial mass, whereby reaction of the inertial mass against the housing is augmented by the liquid medium.

25. The apparatus as recited in claim 24, wherein there is a second pump means arranGed with piston means, inlet means and outlet means generally functionally similar to said first named pump means and arranged oppositely thereto, said second pump means also being arranged to be operated by movement of said inertial mass in generally opposite phase relationship to said first pump means, whereby movement of said liquid medium by said second pump means further augments the reaction of the inertial mass against the housing.

26. The apparatus as recited in claim 25, wherein the piston means of said first and second pump means are connected to opposite sides of said inertial mass so as to reciprocate on their suction and pressure strokes in opposite phase relationship.

27. The apparatus as recited in claim 25, wherein there is a second inertial mass having third and fourth pump means, each with piston means, inlet means and outlet means functioning generally similarly to said first and second pump means, said second inertial mass being arranged to reciprocate out of phase with respect to said first inertial mass, whereby alternating cyclical movement components are imparted to said housing.

29. The apparatus as recited in claim 28, wherein there is a plurality of pump means arranged to function in alternating relationship to direct ambient liquid to said monitoring section, whereby a substantially constant stream of liquid is directed to said monitoring section.

30. The apparatus as recited in claim 28, further comprising walled means defining a float chamber, and sensing element means in said float chamber isolated from said liquid.

31. A remotely operable marine monitoring unit adapted to monitor ambient water, said unit comprising: a. a housing, b. a monitoring section in said housing adapted to receive and discharge sample water of said ambient water, c. monitoring means located at said monitoring section, and d. a plurality of pump means adapted to draw in ambient water and to direct sample water therefrom to said monitoring section, said pump means arranged to function in alternating relationship to direct ambient liquid to said monitoring section, whereby a substantially constant stream of liquid is directed to said monitoring section, each of said pump means comprising:

32. The apparatus as recited in claim 31, wherein there is wall means defining a float chamber, sensor responsive means in said float chamber isolated from said liquid, and sensor means arranged to be in operative contact with sample liquid at said monitoring section.

33. In a body adapted to function in an aqueous liquid, such as ocean water, and having an exposed surface adapted to be in contact with said liquid, apparatus to prevent attachment of matter, such as marine organisms, to said surface, said apparatus comprising: a. an inertial mass arranged to move in a predetermined cyclical path with respect to said body, said inertial mass being so arranged that said cyclical path has a substantial reciprocating vectorial component of acceleration, whereby a corresponding reciprocating component of acceleration is imparted to said body, b. means to react said inertial mass against said body to cause corresponding cyclical movement of said body, c. means to move said inertial mass in said cyclical path at a frequency sufficient to minimize attachment of said matter to said body, and d. said body and said mass each having a center of inertia spaced from one another, and said mass being so arranged that its vectorial component of acceleration is spaced from the center of inertia of the body, whereby a cyclical rotational vectorial component is imparted to said body.

34. The apparatus as recited in claim 33, wherein there is: a. a second inertial mass having a center of inertia spaced from the center of inertia of the body and arranged to move on a predetermined cyclical path with respect to said body, b. second reacting means to react said second inertial mass against said body to cause cyclical movement of said body, and c. second moving means to move said second inertial mass in its cyclical path.

35. The apparatus as recited in claim 34, wherein said second moving means is arranged to move said second inertial mass out of phase with said first inertial mass to impart alternating rotational vectorial components to said body.

37. The apparatus as recited in claim 36, wherein said circuit means comprises: a. a plurality of electronic check valve means, each being connected in series with a respective actuator and connected therewith across a source of alternating current so that each check valve means passes current only during one set of either positive or negative half cycles of the alternating current, b. a plurality of gating means, each being connected to gate a respective check valve of one actuator, and being operatively connected with another of said actuators so as to receive its gating power therefrom, and c. a plurality of gating delay means, each operatively connected to a respective gating means and arranged to delay operation thereof for at least a succeeding half cycle of the half cycle set on which its gating means operates after operation of its gating means on a previous half cycle of the half cycle set on which it operates.

40. The apparatus as recited in claim 39, comprising a diode connected in series with each of said gating delay means.

42. The apparatus as recited in claim 37, wherein: a. each of said gated electronic check valve means comprises a silicon controlled rectifier means, and b. each of said gating delay means comprises a capacitance means and resistance means in parallel and diode means in series therewith, whereby the capacitance means is charged during the gating operation, with the charge being drained at a rate slow enough to block regating by a subsequent half wave of the set of half waves on which it operates, with such blockage being reinforced by means of a voltage drop across said other actuator, the silicon controlled rectifier means of said other actuator having been preferentially gated by reason of said blockage of the gating of the silicon controlled rectifier means of the one actuator.

43. The apparatus as recited in claim 37, comprising: a. a plurality of second check valve means, each being connected in series with a respective actuator across a source of alternating current to pass current only on the other set of either positive or negative half cycles of the alternating current, b. a plurality of second gating means, each being connected to gate a respective one of said second check valve means of one actuator, and being connected with another of said actuators to receive its gating power therefrom, and c. a plurality of second gating delay means, each being operatively connected to a respective one of said second gating means and arranged to delay operation thereof for at least a succeeding half cycle of said other half cycle set after operation of the related second gating means on a previous half cycle of said other half cycle set.