US3108954A - Safety device for centrifuges - Google Patents

Description

vP. STEINACKER SAFETY DEVICE FOR CENTRIFUGES oct. 29, 1963 2 Sheets-Sheet 1 Filed April l. 1960 PETER STE/NACKER.

Oct. 29, 1963 P. sTElNAcKER SAFETY DEVICE EoR cENTRIEuGEs 2 Sheets-Sheet 2 Filed April l. 1960 1 I N VE N TOR.

PE TER STE/NAC/{ER United States Patent() 3,108,954 SAFETY DEVICE FR CENTRIFUGES Peter Steinacker, elde, Westphalia, Germany, assigner to Westphalia Separator, A.G., Westphalia, Germany, a

corporation of Germany Filed Apr. 1, 1966, Ser. No. 19,427 Claims priority, application Germany Apr. 2, 1959 7 Claims. (Cl. 233-21) Conventional high-speed centrifuges, capable of attaini ing a high number of revolutions per unit of time, are usually provided with a hood or cover member which is either mounted on the centrifuge surrounding frame or is hingedly attached thereto, said hood cover serving to enclose the upper portion of the centrifugal drum or serving to seal an opening in the upper portion of the centrifugal drum surrounding outer casing. In the case of centrifuges having free liquid outlets, such covers or hoods are often subdivided by means of intermediate partitions into axially disposed adjacent collecting chambers for the separated components obtained during centrifugal operations. Where flowable materials, such as liquids, are centrifugally processed, the separated fractions are urged during centrifuging into such different chambers through the gap existing between the drum and the separating partition.

It is well understood that before a centrifuge may be taken apart for the purpose of cleaning, the outow of materials from the drum must be terminated, and Jthe drum itself Ibrought to a standstill. Unfortunately much time is wasted during the period between the cut-off of the feed material to the drum and the point where the drum itself has come to rest. Generally, in the case of centrifuges of the aforementioned type, after the stopping of the centrifuge feed material, the draining of the drum, the disconnecting or shutting olf of the drive motor, and the switching on of the brake to bring the centrifugal drum to a standstill, the hood or cover may be forthwith opened for access thereto without danger to the service personnel.

With respect to newer centrifuge constructions, particularly those in which the separated phases are drawn off by means of small axially arranged peeling discs or cups, the feed and outlet conduits are all, or at least in part, fastened to the hood or cover and extend downwardly therethrough into the drum. Consequently, the hood or cover may only be opened after disconnecting these conduits Within the drum from their points of connection to and through the cover.

In making these conduit connections, the little peeling discs, which are axially provided on a shaft, are connected via the shaft or a conductor element to the hood so that they are positioned co-axially -to the axis of the dium whereby said discs stand free from the corresponding disc chambers positioned in the rotatable drum, and the openings of the disc channels or conduits are disposed in the yconductor element at the particular height of the annular collecting chambers.

In disconnecting the feed and discharge conduits, passing through the hood or cover of the drum, as aforesaid, the revolving drum must be brought to a standstill iirst or else the discs, which will also become disconnected with the disconnecting of said feed and discharge conduits,

3,1%,954 Patented Oct. 29, 1963 will fall into the rotating drum and be damaged by the moving parts. Besides the possibility of considerable damage to the various drum parts, the servicing operator is placed in danger due to the possi-ble deflection of broken parts from the open drum.

While a tachometer may be attached to the centrifuge to indicate the number of revolutions of the drum axle, such devices and indicators are not accurate at low speeds. This may be explained 4by the fact that for the purpose of attaining increased precision of readings of the number of revolutions at high speeds the zero point, i.e. the point indicating that the centrifuge has come to a standstill, must be suppressed. As a result, even with the known indicators, the exact point where the centrifuge has come to a standstill may not be actually perceived by the operator without opening the drum hood or cover.

It is an object of the present invention to overcome the foregoing drawbacks and to provide a safety device for centrifugal drums, having means for blocking the release of the flow conduit secured to the cover or hood of the centrifugal Idrum at the opening therein while the drum is being rotated and energizing means actuable upon the stopping of the drum rotation for releasing said blocking means.

Other and further objects of the invention will become apparent from a study of the within specification and drawings in which:

FIGURE l is a diagrammatic side view partially in section of a centrifugal drum hood or cover having inlet and outlet conduits attached thereto, illustrating the safety device in accordance with one embodiment of the invention;

lFIGURE 2 is a diagrammatic side view of the centrifugal drum hood of FIGURE l illustrating the manner of conduit attachment;

FIGURE 3 is a top view of the embodiment shown in FIGURE l;

FIGURES 4 and 4a are diagrammatic enlarged side views, partially in section, of two embodiments of a safety device in'accordance with the invention, and

FIGURE 5 is a diagrammatic view of a circuit for operating the safety device of the invention.

In accordance with the invention, it has been found that the aforementioned disadvantages may be overcome by providing a safety device yfor a centrifugal dnum havin-g an outer hood covering the drum during normal operation and at least one` ow conduit extending through an opening in the hood into the `drum for passage of flowable material therethrough, wherein said conduit is releasably secured to said hood at said opening during normal operation. This safety device comprises blocking means normally preventing the opening ofthe drum cover otherwise caused for example by releasing the inlet and outlet conduits and energizing means actuable upon the cessation of rotation of the drum Vfor releasing the blocking means. In this connection, the blocking -means may specifically prevent the disengagement of the feed and outllow conduits passing through the hood or cover and prevent the opening of the hood or cover itself until the drum has reached a position of rest. At this point energizing means are actuated which release the blocking means and allow the disconnection of said conduits and the opening of the drum cover. Consequently, in accordance with the invention, a premature disconnecting of the feed and discharge lines or a premature opening of the drum cover closure elements is no longer possible, and the aforementioned danger, heretofore present, is completely eliminated.

An essential feature of the invention concerns the energizing means for automatically releasing the blocking means upon the drums coming to a standstill. In this regard a suitable generator may be positioned on the centrifuge drive shaft or on a suitable shaft connected for rotation simultaneously with the drive shaft. By means ofthe rotation of said shaft, the generator produces a convenient voltage, depending on the number of revolutions of said shaft, which is connected, either directly or via various suitable relay circuits, so as to sense the point at which the centrifuge reaches a standstill. The generator may be connected, either as a shut off for the releasing means for the blocking means during the rotation of the drum, which actuates said releasing means upon the drums reaching a standstill, or said generator may act in a positive manner to keep the blocking means in blocking position during the rotation of the drum, and upon the drums reaching a standstill, causing the releasing means to operate. However, it will be realized that any current source may be used which directly or indirectly acts in consequence of drum rotation to energize and deenergize the releasing means for the blocking means, in addition to the simple generator means as described.

In accordance with one embodiment of the invention, the blocking means comprises a blocking arm for preventing the disconnection of the feed line and a stopping arm for preventing the disconnection of the discharge line and conductor element passing into the drum. These arms are suitably provided on a rotatable cylinder element appropriately seated on the drum cover. The cylinder is provided with a recess defined in its outer surface which releasably receives the end of a rod positioned for movement back and forth within a chamber adjacent said cylinder and also preferably seated on said drum hood or cover. Said rod is for example spring loaded so that said rod end is normally urged into the cylinder recess. The other end of said rod is slidably received within an electric coil element. Said coil is connected in circuit with the generator on the centrifuge drive shaft or other means used for sensing the cessation of drum rotation so that when the drive shaft ceases to turn and for example said generator, accordingly, ceases to generate voltage, a relay is switched sending current through the coil surrounding said other end of the rod. By reason of such current, said rod is withdrawn from said recess into the coil, permitting the cylinder to turn freely and displace said blocking arm and stopping arm or lever from their blocking positions. The drum connections, through the hood, may now be disengaged with safety.

Alternately, the coil element and the spring-loaded feature may be reversed in operation so that the rod is normally urged out of said recess and upon actuation of said rod in the opposite direction, by energizing said coil, the cylinder and, in turn, the blocking arm and stopping lever are held in safety position.

It will be appreciated that the particular arrangement for engaging said blocking means in place and for releasing said blocking means upon the stoppage of the centrifuge rotation is not critical. Accordingly, since the generator is to be operated only during the time the lcentrifuge is rotating, the generator may be disposed for operation with respect to any shaft so long as that shaft rotates simultaneously with the shaft of the centrifugal drum and ceases to `rotate at the same moment as that of the centrifuge shaft. cluding relays for example may be provided for energizing the coil iny response to the rotation or cessation of rotation of the drum either to urge said rod into said recess or withdraw the same therefrom as the case may As a further preferred feature, the blocking means may be provided with a suitable arresting element suchas a coil spring normally urging the blocking means into the closed position, i.e. blocking the opening of the hood or cover so that the rod may be replaced again in locking position in said recess. Moreoventhe circuit means may be provided so that the current supply to the `drum motor Generally, any circuit means inonly flows when the blocking means is in blocking posi tion closing the hood or cover.

As a further feature of the invention, the circuit for the energizing means, for automatically releasing the blocking means, may include an additional element capable of emitting au acoustic -or optical signal, such as the ringing of a bell or the ashing of a light, at the tnoment the centrifuge comes to a standstill. Such asignal would indicate the stoppage of rotation of the drum to the service personnel immediately, and thus effect a saving in otherwise wasted time after the centrifuge has stopped and before the workmen open the hood or cover.

Referring to FIGURE l, a stationary hood 1 iseprovided spaced from and extending around the moving centrifugal drum so as to enclose the same. Hood 1 is provided with a' central aperture 2 through which the conductor 4, equipped with oneV or more connecting flow lines such as line 3, is introduced into the drum interior. Conductor 4 is retained by means of a tension ring 5, cooperating with a tension screw (see FIG. 2) solidlyon flange rim 7 of the stationary hood 1. The stationary disc shaft 8, containing one or more peeling discs 14 for separating the different phases of the ilowable material to be centrifuged, is positioned loosely in the upper portion of the drum before closing the drum hood. In this manner, the upper portion of said disc shaft 8 projects. through the conductor 4 and is centered in place by the threaded handle body 9 drawn tightly against its seat in the conductor 4, which is provided with a correspondingly threaded portion forthis purpose. The elbow portion 11 of the feed line 12 is fastened tightly to the upper end of handle body 9 by means of handle body 13. For this purpose handle body 13 and handle body 9 are provided with corresponding threaded portions.

Upon the termination of a centrifuging operation, after the closing of of the feed line 12 and outlet line 3, 'elbow portion 11 may be detached by unscrewing handle body 13 and removed without danger. On the other hand, the detachment of handle body 9 and of tension screw 6 must await the cessation of rotation of the drum or else disc shaft 8 if prematurely releasedwill be downwardly displaced causing the peeling disc 14 to fall against the rotating drum part 15. Accordingly, the danger of damage to the drum parts and injury to the service personnel may result.

For this purpose, in accordance with the invention, as indicated in FIGS. 2 and 3 a rotatably mounted cylinder 18 is provided on the drum hood, having a blocking arm 16 and a stopping lever 17. In the safety position, the blocking arm 16 is so disposed that its upper end portion abuts a corresponding gripping extension of handle body 9 while the outer portion of stopping lever 17 abuts tension screw .6 preventing lthe loosening of said screw. As may be seen from FIGURE 3, When the safety device is in blocking position, a premature disconnection of the handle body 9, to which is connected the shaft 8 carrying the llittle disc 14, as well as a disconnection of conductor 4, is completely prevented. Only upon the stoppage of rotation of the drum, so that the energizing means may automatically actuate the releasing mechanism for the blocking means, will the drum cover be able to be opened.

As shown in FIGURE 4, cylinder 18 is provided with a recess, or bore hole 19 into which a spring-loaded bolt or rod 21 may be received in locking engagement. Rod 211, surrounded by loaded spring 20, is positioned for back-and-forth movement within slide cylinder 24, preferably fxedly attached to the drum hood 1. Spring 20 is positioned between retaining disc 22, `attached to bolt' 21, and the annular counter-bearing 23, fixed -to the inside wald of cylinder 24; The'distal end of bolt Z1, .e. the end remote from cylinder 18, projects within a wire coil ZS, connected in circuit with an energizing means such as a generator (not shown) for actuation upon the cessation of rotation of the drum. Bolt 21 is drawn further within the core of coil 2S against the force of loaded spring 20, acting at one end against fixed bearing 23 and at the other against disc 22 on bolt Z1, when said coil is energized by current passing therethrough. In this way, the locking of cylinder 18, by the end of bolt 21, within recess 19, is released, permitting cylinder 18 to be rotated and blocking arm 16 and stopping lever 17 to be displaced from blocking position.

In order to ensure that the blocking means for hood 1 are always in the blocking position when the drum is running, cylinder 1'8 is preferably provided in the embodiment shown in FIGURE 4 with a central passage for rotatably mounting the cylinder onto bearing bolt 27 iixedly attached to hood 1. The upper portion of the channel of cylinder 1,8 is enlarged in order to receive therewithin loaded coil spring 26. Spring Z6 is attached at one end to bolt 27 and at the other to cylinder 1'8 under tension normally urging cylinder 18 and in turn blocking ann 16 and stopping lever 17 into blocking position. In this manner, upon the release of blocking means 16 after an opening of the drum cover 1, the counter-action of spring 26 automatically tu-rns cylinder 18 back to the starting position for blocking engagement, so that recess 19 is again placed in communication -with bolt 21. Accordingly, the hood 1 will be safely maintained in closed position when the drum motor is actuated.

Alternately, or besides the loaded spring arrangement in cylinder 18, an extension contact arm may be provided on the end of bolt 21 remote from recess 19 as shown in FIGURE 4a. In this case, contact arm 28 is positioned with respect to safety switch contacts v for closing the overall circuit Ifor the drum moto-r only when bolt 21 is positioned in recess 19, thus ensuring that the blocking position is maintained before the drum can be rotated. The energizing of the coil 2.5 for releasing rod 21 from blocking position is suitably effected by generator G positioned for rotation directly or indirectly with the drive shaft of the drum motor as is more clearly seen in FIGURE 5.

Referring to FIGURE 5, the operation of the preferred circuit for actuation of the centrifugal arrangement which shows various contacts in closed position is as follows. Upon closing main switch S, current ows across closed contacts r of relay R when drum is stopped and closed contacts u1 of the pressure switch U normally held in closed position under spring pressure, and through coil 2.5 completing the circuit. further within coil 25 now energized and out of recess 19 so as to eect release of the bolting position and permit opening of the hood 1. Ann 28 connected to bolt 21 simultaneously moves outwardly thus opening the contacts v.

If -pressure switch U is now actuated while switch S remains closed, contacts u1 are opened causing inter-ruption of current flow to coil 25. Moreover, if recess 19 is again aligned with the bolt 21, due to the action of spring 20, bolt 21 moves back into locking engagement with recess 19. Since contacts v are only closed when bolt 21 is in locking position, upon such actuation of pressure switch U, but only when the locking position is again maintained, current passes via closed switch S, contacts v and contacts u2 to actuate relay W which thus automatically closes main switch X to start electric motor M, the driving source for rotation of drum D via transmission sh-aft E. Simultaneously, relay W closes self-holding contacts w, so that relay W remains actuated and in turn switch X remains closed even after the release of pressure switch U. Current to relay W is now provided in this connection via normally closed contacts y of pressure switch Y and the self-holding contacts w.

Upon switching on of motor M, generator G positioned on any desired axle of the drive transmission means, produces a predetermined voltage sucient to actuate a shift of relay R and in -turn to cause the opening of contacts r. Coil 25 accordingly remains deenergized upon release of pressure switch U even though contacts u1 are Bolt 21 is temporarily moved again closed, since contacts r remain open due to the shift of relay R caused by generator G.

iIn order to shut olf motor M, pressure switch Y need merely be pressed. This interrupts current ow to relay W `which shifts to cause the openings of switch X. Simultaneously, current to self-holding contacts w is also interrupted.

As llong as drum D is running, even after the switching off of motor M, 4generator G still produces voltage sufhcient to actuate relay R to maintain contacts r in open position. Only upon the cessation of drum rotation does the generator voltage decline, and in turn the ilow of current to relay R, whereby contacts r are again closed and current caused to ow through coil 25. Now, bolt 21 is drawn further within coil 25 and out of recess 19, releasing cylinder 18 'for opening the drum hood. Blocking arm `16 and stopping lever 17 may accordingly be rotated out of blocking position together with cylinder `18 so as to permit release of handle body 9 and screw 6.

Coil 25 may be suitably deenergized during prolonged interruptions in centrifugal operation by merely turning off switch S.

As aforesaid, the energizing current for coil 25' is switched on by :suitable circuit means upon the stoppage of rotation of the drum as sensed Iby the suitably situated generator or other means with respect to the drive shaft of the centrifuge or other suitable shaft element rotating simultaneously with the drum and ceasing to rotate at the same moment as said drum ceases to rotate. The voltage produced Iby the generator during rotation of the drum may be conveniently utilized for activating a relay, which, upon reaching a specific voltage value, for instance,'a voltage value of zero (when the drum reaches a standstill) switches on, via closed circuit contacts, another current which may pass to coil 25. The switch yfor this other current source may be appropriately coupled with the main switch for turning on and off the centrifuge drive so that, upon switching off the centrifuge, the current to therelay is switched on and ready to energize the coil upon the generators reaching a zero voltage value.

It will be appreciated that, while the foregoing specitication and accompanying drawings have been set forth for the purpose of illustration, it will be obvious to those skilled .in the art that various modificationsv and changes may be Imade without `departing from the spirit and scope of the invention, which is to be limited only by the scope of the appended claims.

What is claimed is:

l. Safety device-equipped centrifugal drum arrangement comprising a centrifugal drum', an outer hood covering the drum during normal operation, means defining an opening in said hood, one iiow conduit extending into said drum fOr passage of flowable material therethrough, means releasably securing said conduit to said -hood at the opening means, blocking means operatively positioned at said means releasably securing said conduit for preventing during rotation of the drum the release by the releasable securing mems of said conduit so secured to said hood, means responsive to the rate of rotation of the drum operatively connected with respect to the drum, and energizing means operatively connected with the responsive means and with said blocking means, `said energizing means being actua-ble by said responsive means for releasing said 4blocking means only upon the complete` cessation of rotation of the drum.

2. Arrangement according to claim l wherein said means releasably securing said conduit to said hoo-d includes a closure element yfor closing said opening and fastening means for fastening said closure element closed, said conduit being secured to said hood via said closure element, and said blocking means including a displaceable blocking arm for blocking the release of said fastening means and releasable locking means for securing said blocking arm against displacement, said'locking means being released upon actuation of said energizing means to allow displacement of said blocking arm.

3. Arrangement according to claim 2 wherein said blocking arm is mounted on a rotatable base, lsaid base being normally urged under spring force to maintain said blocking arm in :blocking position, said base having a recess therein, 'said locking means including a rod movable into and out `of said recess for locking said base against rotation and in turn said blocking arm in blocking position against displacement, spring means being provided for spring urging said rod into said recess, and coil means being provided, energizable by said energizable means, for electrically urging said rod out of said recess.

4. Arrangement according to claim 3 wherein said responsive means includes a iirst circuit having energiza'ble relay means and generator means therein, said generator means being operatively connected with the drum for generating current in said tirst circuit for energizing said relay means as long as said drum rotates, and said .energizing means includes Ian energized Asecond circuit having current interrupting switch means and said coil means therein, said relay means being operatively coupled with said switch means for opening said switch means to interrupt current in said second circuit when said relay Ameans is energized during drum rotation and for closing said switch means to permit current to flow in said second circuit to energize said coil means upon complete cessation of drum rotatiom 5. In a safety device-equipped centrifugal dru-m arrangement including a centrifugal drum, an outer hood covering the drum during normal operation, said hood having means defining an opening therein, a closure element closing the opening, releasable fastening means, said closure element being secured to said hood at said opening by said rele-asable fastening means, and at least one conduit for tiowable material extending through said olosure element and into said drum, the improvement which comprises blocking means operatively positioned at said fastening means for preventing during drum rotation the release of said fastening means, ymeans responsive to the rate of rotation of the drum -operatively connected with respect to the drum, and energizing means operatively connected With the responsive means and with said blocking means, said energizing means being actuable by said responsive means for releasing said blocking Cil ai means only upon the complete cessation of rotation ofV the drum. l

6. Improvement according to claim 5 Vwherein saidL covering the drum during normal operation, said ,hood

having an opening defined therein, a closure element closing said opening, first releasable fastening means, said closure element being secured to -said hood at said opening -by said rst releasable fastening means, a conductor means extending through said closure element and having la pontion insertable into said rdrum, an inlet conduit dened within said conductor means, a peeling disc detined on the exterior 'off said `conductor means :along said insentable portion, a peeling conduit extending through said closure element and provided in flow communication with said peeling disc, a feed conduit, and second releasable fastening means, said feed .conduit being releasably se cured by said second releasable fastening means to said inlet conduit, the improvement which comprises blocking means including a displaceable stopping arm and a displaceable blocking arm operatively positioned ttor preventing the release of said first releasalble fastening means and said second releasable fastening means, respectively, during rotation of the drum, releasaible locking means operatively positioned at said arms for securing said arms against displacement, means responsive to the rate of rotation of lthe drum operatively connected with respect to the drum, energizing means operatively connected with the responsive means and with said locking means, said energizing means being actuable by said responsive means only upon complete cessation of rotation of the drum for releasing said locking means to allow displacement of*y said blocking and stopping arms. Y

References Cited in the tile of this patent UNITED STATES PATENTS Batson et al. July 22,

UNITED STATES PATENT OEEICE CERTIFICATE OF CORRECTION Il. en 1. No.. 3, 10819.54 October 29, 1963 Peter Steinacker It is hereby certified that error appears in the above numbered patent requiring Correction and that the said Letters Patent should read as eerreeted below.

In the grant, lines 2 and 12, and in the heading to the printed specification, line I for "Westphalia Separatorw AG.." nach occurrence, read Westfalia Separator, A.G

Signed and sealed this 21st day of April 1964.

(SEAL) Arrest: EDWARD J BRENNER ERNEST W. SWIDER Attesting Officer Commissioner of Patents

Claims (1)

1. SAFETY DEVICE-EQUIPPED CENTRIFUGAL DRUM ARANGEMENT COMPRISING A CENTRIFUGAL DRUM, AN OUTER HOOD COVERING THE DRUM DURING NORMAL OPERATION, MEANS DEFINING AN OPENING IN SAID HOOD, ONE FLOW CONDUIT EXTENDING INTO SAID DRUM FOR PASSAGE OF FLOWABLE MATERIAL THERETHROUGH, MEANS RELASABLY SECURING SAID CONDUIT TO SAID HOOD AT THE OPENING MEANS, BLOCKING MEANS OPERATIVELY POSITIONED AT SAID MEANS RELEASABLY SECURING SAID CONDUIT FOR PREVENTING DURING ROTATION OF THE DRUM THE RELEASE BY THE RELEASABLE SECURING MEANS OF SAID CONDUIT SO SECURED TO SAID HOOD, MEANS RESPONSIVE TO THE RATE OF ROTATION OF THE DRUM OPERATIVELY CONNECTED WITH RESPECT TO THE DRUM, AND ENERGIZING MEANS OPERATIVELY CONNECTED WITH THE RESPONSIVE MEANS AND WITH SAID BLOCKING MEANS, SAID ENERGIZING MEANS BEING ACTUABLE BY SAID RESPONSIVE MEANS FOR RELEASING SAID BLOCK MEANS ONLY UPON THE COMPLETE CESSATION OF ROTATION OF THE DRUM.

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