US2706561A - Cover closing mechanism for centrifugal machines - Google Patents

Description

COVER CLOSING MECHANISM FOR CENTRIFUGAL MACHINES Filed Nov. 2, 1949 2 Sheets-Sheet 1 fol/ecs- ATTORNEY April 19, 1955 c. A. OLCOTT 2,706,561

COVER CLOSING MECHANISM FOR CENTRIFUGAL MACHINES Filed Nov. 2, 1949' 2 Sheets-Sheet 2 AIR J'OUPCE' .INVENTOR. (#421 if 4. 0L 6077' United States Patent COVER CLOSING MECHANISM FOR CENTRIFUGAL MACHINES Charles A. Olcott, West Milford, N. J.

Application November 2, 1949, Serial No. 125,041

2 Claims. (Cl. 210-63) This invention relates to centrifugal machines and more specifically to an automatic cover closing mechanism for a machine of that type.

It is an object of this invention to simplify automatic cover closing mechanisms for sugar centrifugal machines and to improve their operation.

Patent 2,254,388 issued September 2, 1941 to C. A. Olcott discloses a cover closing mechanism for a sugar centrifugal machine. The machine includes a curb enclosing a centrifugal basket, a cover for the curb, and an automatic mechanism for closing the cover in response to the movement of appropriate centrifugal controls to their positions corresponding to the high speed running of the centrifugal and for opening the cover in response to the movement of such controls to positions corresponding to the condition where the centrifugal basket is at rest. The basket is thus closed during the time when it is important that the heat and moisture be retained therein, to facilitate purging and washing, and is opened for suitable access for discharging the sugar and loading it with a new charge of massecuite. The arrangement disclosed in the patent includes for operating the cover (actually it is a pair of covers) an air cylinder, a retrieving spring and a series of air pressure and solenoid valves, the solenoid valves being operated by appropriate electrical connections which are energized or deenergized corresponding to the running and the at-rest condition of the centrifugal basket.

Cover operating mechanisms of the general type just described have been put into use and a number of benefits are claimed for them by the operators. Among these benefits are the following:

(1) It is possible to reduce the amount of wash water used to wash the sugar in the centrifugal because when the heat is retained and the air is excluded a smaller amount of wash Water is suificient to properly clean the crystals. This reduction in the amount of wash water automatically applied is not a safe operation to follow unless the covers are automatically operated because if the operator should neglect at times to close the covers, then the amount of wash water, which has been automatically predetermined to conform to the closed condition of the curb, is not sufiicient to clean the crystals when the cover is left open, as frequently occurs due to negligence on the part of the operator, and this improperly washed sugar has a very poor quality, and if mixed with other sugar, lowers the quality of the entire mass of sugar being treated in the refinery. Therefore, in operation, as a matter of safety the predetermined amount of wash water is made large enough to insure reasonably satisfactory washing even if the cover may at times not be closed and, of course, such an amount of water is much more than is necessary when the cover is closed with the result that good sugar is lost and must be re-processed at additional cost.

(2) It prevents secondary charging. It has been found that when a full charge of massecuite has been introduced into the basket and the centrifugal speeded up, with the resultant throwing off of the molasses from the basket, the volume of material in the basket is reduced leaving a space into which the operator can put additional massecuite to fill up the basket again, and the operators like to do this because it helps them to centrifuge more sugar with less work. However, this practice is very bad because it causes green molasses to flow through a mass of sugar crystals which have already been partly purged, with the result that the entire mass of sugar is unsatisfactorily purged of its green syrup and the wash water is less effective and this results in the production of sugar which is high in ash content and otherwise low in quality. This secondary charging is apt to take place when the covers are not automatically operated because the operator will not close the covers until he has put in his second and perhaps a third charge of massecuite. The managing personnel of sugar factories who are acquainted with this condition endeavor to order the operators not to engage in secondary charging, but their orders have little effect because the operators can reduce the amount of manual labor by following this bad practice and therefore tend to follow it as soon as the foremans back is turned. When the covers are automatically operated, then, when the machine picks up speed and the molasses is thrown out of the basket, leaving a space in which more massecuite can be charged, the covers are closed preventing the addition of more massecuite and forcing the operator to operate the machines in accordance with the instructions of their employers.

(3) The use of automatically operated covers contributes substantially to the safety of operation of these sugar drying centrifugals. The unloading device commonly used on centrifugals is designed to plow out the sugar while the basket is rotating at low speed and sometimes when an operator has become tired after working for several hours he may think that the machine has come to a stop when actually it may be running at high speed (but so smoothly that no motion is visible) and it all too frequently happens that he will attempt to plow out the sugar by introducing the plow into the running machine with resultant breakages of parts of the unloading device and perhaps of the centrifugal itself and even in some cases serious physical injury to the operator; but the automatically operated cover mechanism prevents these accidents because when the cover is closed (which is its position when the machine is running at high speed), the operator cannot move the unloader into a position where the plow engages the sugar in the massecuite because the covers, closing as they do the basket and curb, prevent any such movement.

It is thus clear that these covers contribute substantially to the safety and efliciency of operation of sugar drying centrifugals. While the arrangement described in the above-identified Olcott patent can be applied to practically any type or design of sugar centrifugal, it has been found that a substantial reduction in the amount of equipment required (and hence in the cost of the equipment and in the maintenance thereof) can be achieved when these covers are installed on centrifugals which are automatically controlled by an automatic controller of the pneumatic type and, moreover, an improvement in operation results.

It is, accordingly, another object of this invention to reduce the expense of operation and of maintenance of centrifugal cover closing mechanisms in centrifugals operated by automatic controllers.

It is a further object of this invention to improve the operation of centrifugals with automatically controlled covers.

The above and related objects areattained in accordance with an exemplary embodiment of the invention by interlocking, in a sugar centrifugal machine, the operation of the automatic cover closing mechanism -with that of the automatic controller used to time the operations of the centrifugal basket. The automatic controller is of the type which makes use of compressed air and may be, by way of example, the device known as the Steps Master Centrifugal Control manufactured by Sugar Machinery Co. of Los Angeles, Calif, and which is described in Steps Patent 1,947,679 issued February 20, 1934. This automatically controlled device is widely used in the sugar industry and controls the operations of the centrifugal. By making use of this type of controller with the coveroperating mechanism of the Olcott patent, it is possible to eliminate a solenoid valve and its related equipment used in the patented Olcott device as well as improve the operation of the centrifugal in some cases, as will be described more fully below after a detailed description of the invention.

The invention will be more readily understood by eferring to the following description taken in connec ion with the accompanying drawings forming a part hereof, in which:

Fig. 1 shows, partly in plan and partly in circuit chematic form, an automatic cover-closing mechanism :1 accordance with the invention; and

Fig. 2 is a front elevation of a centrifugal, partly n section, including the top covers and part of the tctuating mechanism shown in Fig. l.

Referring more specifically to the drawings, Flgs. l and 2 show, by way of example for purposes of il- .ustration, an automatic cover closing mechanism :onstructed in accordance with the invention for a sugar centrifugal machine 11. The machine 11 in- :ludes a fixed casing 12 enclosing a centrifugal basket 13 suspended therein and rotated through a shaft 14 by a motor 15. The motor is supported by a superstructure, not shown, from which the shaft 14 and the basket 13 are suspended so that the centrifugal may ro tate freely within its casing 12. Two top covers 16 and 17 employed for closing the top opening of the centrifugal and all of the cooperating mechanism are shown in the closed position in Fig. 2 and in the fulllines in Fig. l, and these are shown in the open position in the dotted lines in Fig. 1. The closed position corresponds to the high speed running condition of the centrifugal while the open position corresponds to the period after the normal running cycle has been completed to make the basket 13 accessible for the discharging and charging operations performed while the machine is at rest or turning at low speed. The covers are opened and closed by a group of levers and arms (which will be described below) controlled by an air pressure cylinder 18 and a spring 19 both an chored to a base plate 28. The piston in the cylinder 18 is operated by compressed air from a source 21 which is connected to the cylinder 18 by means of a pipe 22, a three-way valve 23 of any well-known type, and pipes 24 and 25. By way of example, a suitable valve is shown in Fig. 3 of the above-identified Steps patent. A pipe 26 vents air from the valve 23 at the desired venting times. The air source 21 is also connected to the pipe 24 through the pipe 22 and valve 23 and is connected through the pipe 24 and the T joint 27 to a timing cabinet controller 28 for centrifugals which is of any suitable type which operates in response to admission of air pressure to the timing cabinet. By way of example, it can be of the type fully shown and described in the above-identified Steps patent so the details of the be repeated at this point. By means of a pipe 29 to an air pressure cylinder 30 the brakes 31 are applied at the proper time in each cycle of operation.

Before describing the operation of the pneumatic equipment briefly mentioned above, details of the cover operating lever mechanism will first be given. Cover 17 swings on bar lever 40 from a pivot 41 in plate 42, the lever 40 being attached to a fiat plate 43 which is bolted to the cover 17 and which is attached by means of coupling 44 to the rod 45 fastened to the piston in the air cylinder 18. When the rod 45 is actuated to the right by air cylinder 18, the cover 17 is rotated as a unit with bar 40 in a horizontal plane about the pivot 41 to its extreme right hand position (the full-line position in Fig. 1) sliding over the top surface of the casing 12 to close the left hand portion of the circular opening 32 in the casing. Movement of the bar 40 also controls the operation of cover 16 simultaneously with the actuation of cover 17. Cover 16 is actuated to close the right hand portion of the circular opening 32 in the following manner. As bar 40 is actuated to the right it moves a bar 46 which is pivoted to the bar through pin 47. The bar 46 is pivoted in turn through pin 48 to the upper end of a bell crank lever 49. The latter is pivoted through a pin 50 which is rigidly fixed in the top of casing 12. At its lower end, bell crank lever 49 is bolted by means of bolts 51 to the right hand cover 16. As bar 46 is actuated to the right, it rotates the upper end of the bell crank lever 49 to the right about its pivot pin 50 in turn operating cover 16 toward the left. The cover 16 slides also in a horizontal plane over the top surface of the casing 12 to close the right hand portion of the circular opening 32. Two flat bars 52 and 53 are bolted to the cover 16. These bars serve to cover any opening which timing cabinet 28 need not 86 ing said air supplying means may exist in the joint between adjacent edges of the covers 16 and 17 when they are closed. The covers 16 and 17 together with the bars 52 and 53 effectively cover the top opening 32 in the casing 12 and substantially prevent the flow of air through the top opening. For a more detailed description of top cover linkage mechanisms of the type briefly described above reference is made to the above-identified Olcott patent.

The operation of the arrangement shown in Figs. 1 and 2 will now be described. Assume that the covers 16 and 17 are open and the basket 13 in the centrifugal machine 11 has just been charged. The valve 23 is then manually turned by the operator to the On position to admit compressed air from the source 21 to the cylinder 18 by way of pipe 22, valve 23 and pipes 24 and 25 to actuate rod 45 to the right to close the covers 16 and 17 and at the same time to admit air to the controller cabinet 28 at the time when the power is turned on to accelerate the machine to full speed so that the sugar can be purged, washed and dried. All of these latter operations are automatically timed by the equipment in the cabinet 28 according to the periods of time adjusted by the setting of the dials 54, 55, 56 and 57. As fully set forth in the disclosure of the above-identified Steps patent, the automatic equipment in cabinet 28 times all functions up to and including the application of the airoperated brake 31 which stops the centrifugal 11. Thus, when the operator returns to the machine which has been under the control of the timing equipment in the cabinet 28 up to the end of its running cycle, he finds the machine stopped with the air brake 31 set by reason of air admitted to the cylinder 30 and the basket 13 holds sugar which has been purged, washed and dried. To discharge the sugar from the basket the operator must release the brake 31 which he does by moving the handle of the valve 23 to the OE position. This shuts off pressure from the source 21 permitting the air pressure in the pipe 24 to be exhausted to the atmosphere through pipe 26 and thus has the effect of permitting all of the timers applying to the particular centrifugal 11 to return to zero and also to vent the cylinder 18 allowing the spring 19 to move the bar 40 to the left opening the covers 16 and 17. In the zero position of the timers in the control cabinet 28 of the Steps type, a three way valve controlled by the timing gears set by one of the dials 54 to 57, inclusive, cuts off air pressure from brake cylinder 30 and vents this cylinder to the atmosphere through the cabinet 28.

It will be noted that in combining the operation of the Steps controller with the cover closing mechanism described in the Olcott patent, the solenoid valve, the centrifugal switch and various electrical connections used in the patented Olcott device are not necessary. The benefits are substantially the same but in coordinating the opening and closing of the covers in a manner in which they are responsive to manual operations normally performed at the proper times, the amount of equipment necessary to control the covers is substantially reduced. This naturally makes the covers and their operating equip ment less expensive to manufacture and install and also reduces the amount of equipment which has to be maintained. Another advantage of the present arrangement is that the operation is improved in all cases where it is desirable to have the covers closed during deceleration of the centrifugal (which is not the case in the arrangement covered in the Olcott patent).

While the Steps control arrangement is described herein by way of example as a satisfactory controller, it should be clearly understood that any other suitable pneumatic controller can be used instead. Moreover, the present invention is not limited to the use of the exact cover operating linkages described in the Olcott patent.

Various other changes can be made in the embodiment described above, without departing from the spirit or scope of the invention as indicated by the claims.

What is claimed is:

1. A sugar centrifugal machine comprising a curb having an opening therein, a basket within said curb, means for rotating said basket, a brake for said machine, a cover for the curb, a cylinder having a piston therein operative between two positions at which the cover is respectively open and closed, automatic timer means to apply wash water to said basket and to apply said brake at predetermined times after the timer means is energized, means for supplying high pressure air, means for connect to said automatic timer means and to said cylinder, and means including a single pneumatic valve in said connecting means for simultaneously starting the energization of said timer means and the movement of said piston to the cover closing position and for simultaneously controlling the deenergization of said timer means and the movement of said piston to the cover opening position.

2. A sugar centrifugal machine comprising a curb having an opening therein, a basket within said curb, means for rotating said basket, a brake for said machine, a cover for the curb, a cylinder having a piston therein operative between two positions at which the cover is respectively open and closed, automatic timer means to apply wash water to said basket and to apply said brake at predetermined times after the timer means is energized, means for supplying high pressure air, means for connecting said air supplying means to said automatic timer means and to said cylinder, and means including a single pneumatic valve in said connecting means for simultaneously starting the energization of said timer means and the movement of said piston to the cover closing position and for simultaneously controlling the deenergization of said timer means and the movement of said piston to the cover opening position, said valve being of the three-port, two-position type and having one of its ports connected to said source, a second of its ports connected to said timer and to said cylinder, and the third of its ports connected to a vent.

References Cited in the file of this patent UNITED STATES PATENTS 1,947,679 Steps Feb. 20, 1934 2,254,388 Olcott Sept. 2, 1941 2,325,406 Johnson July 27, 1943 2,328,394 Ncuman Aug. 31, 1943 2,521,054 Ellis Sept. 5, 1950

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