US3002287A - Control means for solvent recovery machine - Google Patents

Description

Oct. 3, 1961 J. c. SMITH CONTROL MEANS FOR SOLVENT RECOVERY MACHINE 5 Sheets-Sheet 1 Filed Feb. 18, 1960 MILE T awn/5n INVENTOE.

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CONTROL MEANS FOR SOLVENT RECOVERY MACHINE Filed Feb. 18, 1960 5 Sheets-Sheet 5 TIMER 55 iizkiidii.

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CONTROL MEANS FOR SOLVENT RECOVERY MACHINE Filed Feb. 18, 1960 5 Sheets-Sheet 5 L1 1 16i 5 53 /AEf?A TE/ 35 I I gm 1.. J

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' BY k r/mmm. rbiv'rk'o' l. .SW/Tt/l I j $g Chemical Industries, Inc., Detroit, Mich., a corporation of Michigan Filed Feb. 18, 1960, Ser. No. 9,532 2 Claims. (CI. 34-45) This invention relates to automatic control means for solvent recovery tumblers.

At the present time it is the general practice in the dry-cleaning industry to provide so-called automatic control for solvent recovery tumblers by means of program or interval timers. volves, however, judgment on the part of an operator. The operator, exercising judgment acquired by long experience, determines the optimum length of the cycle, and pre-sets the time cycle on the automatic control each time a load is run. The length of the time cycle required to recover completely the solvent from a load of garments is dependent upon a number of factors, such as operating steam pressure and its resultant temperature, the quantity and the temperature of the cooling water, the size of the load being recovered, and the kind of fabric in the load. The operator will usually determine, for example, that with a 35 pound load of miscellaneous fabrics in a given recovery unit, and operating the unit at say 35 pounds steam pressure and with the usual water flow conditions, the solvent can be completely recovered in say 12 minutes. In such case, at the expiration of the 12 minute period, the recovery part of the cycle is terminated and the machine is turned, by either manual or automatic means, to aeration.

It will be noted that in the present day so-called automatic control for solvent recovery tumblers, the operator has to determine the time cycle for complete recovery of the solvent by analyzing the various factors involved. Optimum, even satisfactory, operation of the recovery unit depends entirely on the operators judgment. It is apparent that if the solvent, a costly item, is to be completely recovered, the recovery period should be adequately long. But having too long a recovery period is also highly undesirable. In the first place, it is wasteful of time and power. Secondly, it places the fabrics in danger of being damaged, for after removal of the solvent the temperature rises sharply and the excessive heat may cause shrinkage in the fabrics being processed.

The present invention provides means in a solvent recovery tumbler capable of sensing automatically when the solvent is substantially completely recovered from the load being processed. The means provided by the present invention takes into consideration all the variables involved and has the ability to sense automatically when recovery is complete. It then automatically switches the unit from solvent recovery to aeration.

My invention will be clearly understood from the following detailed description of a preferred embodiment taken together with the drawings in which:

FIG. 1 is a view, partly diagrammatic, partly perspective, of a solvent recovery machine embodying my present invention and showing the recovery phase of the cycle;

FIG. 2 is a view similar to FIG. 1 showing the aerating phase of the cycle;. v

FIG. 3 is a wiring diagram showing the electrical components, switches and connections when the recovery machine is o a FIG. ,4 is a wiring diagram similar to FIG. 3 but showing the switches and connections during the recovery phase of the cycle; and

Such automatic control, in-

Referring now to FIGS. 1 and 2, there is shown a solvent recovery machine comprising a cylindrical perforated drum 10 mounted (by means not shown) for rotation about its horizontal axis. Drum 10 is enclosed in a cover or housing 11 (indicated in the drawing in dotted lines) and is arranged to be driven rotationally by a belt 12 driven by an electric motor 13. Housing 11 is provided at the front with an access door (not shown) through which the clothes or other material to be treated are introduced into the drum and through which they are removed after the entrained solvent has been recovered therefrom.

Below drum 10 is a generally closed box-like sump 18 having in .its upper surface near one end thereof an opening 19, and having near its other end a vertical slot 20 providing passage completely through the sump 18. Slidable into the. sump 18 at the slot end thereof, and

cross-wise of the slot 20, is a lint trap 21 having a screen bottom for catching lint blown ofi from the clothes or other material during tumbling in the drum 10.

Disposed within sump 18 below opening 19 is a heating unit 22 having coils 23 through which is circulated steam supplied through a pipe 25 under control of a steam-inlet valve 26. Disposed centrally within sump 18 is a solvent-vapor condensing unit 27 having coils 28 through which a coolant, such as cold water, is circulated, the coolant being supplied through a pipe 29 under control of a water-inlet valve 30.

Immediately beneath condensing unit 27 and leading down from the sump 18 is a duct 31 connecting to the out-let of a blower unit 32 arranged to be driven by an electric motor 33. Blower 32 is also in communication by way of an L-shaped duct 35 with slot 20. Interposed in duct 31 between blower 32 and condensing unit 27 is a junction-box connectionto an exhaust branch duct 36 extending laterally from duct 31. The flow through exhaust branch 36 is controlled by a damper valve 37 located in the junction box.

By means of the linkage identified generally by the reference numeral 38, the damper valve 17 in the air inlet. 16, the steam-inlet valve 26, the water-inlet valve 30, and the damper 37 in the branch duct 36 are all interconnected for simultaneous actuation by an electric servomotor 39.

The solvent condensate which collects in the bottom of the sump 18 is carried off through a centrally positioned pipe 40 leading from the floor of the sump to a water separator 41 from which therecovered solvent is conductedthrough a pipe 42 to. a suitable collecting recep tacle (not shown), and from which the waste water is discharged through a pipe 43. In accordance with my present invention there is located in the L-shaped duct 35 a thermal control unit or temperature-sensitive switch 45 Whose function and operation will be described later.

As' indicated previously, FIGS. 1 and 2 are similar with the exception that FIG. 1 illustrates the conditions of the various components of the system and the air-flow path during the solvent removal or recovery phase of the cycle, while FIG. 2 illustrates the conditions of the components and. air-flow path during the aerating phase of the cycle.

It will be noted from FIG. 1 that during the solvent recovery phase of the cycle, damper 17 of the fresh air Patented on. 3, war

inlet 16 is held in closed position, that the steam-inlet valve 26 and the water-inlet valve 30 are held in open position, and that the exhaust damper 37 is held closed with respect to the exhaust duct 36 but open with respect to in duct 31. Under these conditions, with blower 32 running, air is continually circulated through the drum 10. The air path may be traced from the blower 32 up through the in duct 31, through the condensing unit 27 into the sump 18, then through or past the heating unit 22, up through the opening 19 and into the drum 10, through the perforations in the drums circumferential surface, through the fabric contents of the drum, then out through the drum perforations, and down through slot 20 into the return duct 35 and back to the blower.

As the air passes through or by the heating unit 2 2 the air is heated to, for example, 230 F., and this hot air passing through the clothes or other fabrics in the drum 10 accelerates vaporization of the residual solvent contained therein. The temperature of the air is lowered rapidly as it gives up its heat to satisfy the latent heat requirements of the solvent in the garments. Usually, the solvent is perchlorethylene or trichlorethylene. When the solvent-laden air reaches the cooling or condensing unit 27 (-via slot 2!), duct 35, blower 32 and duct 31) the solvent vapor is condensed out of the air and collects on the floor of the sump from which it is carried away by the pipe 40 to the unit 41. Immediately after removal of the solvent vapor from the air by the condensing unit 27, the air is reheated by the heating unit 22 for passage again through the drum 10 and its contents.

When the solvent has been substantially completely removed from the clothes or other material contained in the drum 10, the hot air entering drum 10 is no longer lowered rapidly in temperature by reason of giving up heat to satisfy the latent heat requirements necessary to evaporate the solvent out of the garments, and consequently the air leaving the drum has almost the same temperature as the hot air entering the drum. Thus, the air which is now flowing through slot 20 into duct 35 and past the thermal control switch 45 is substantially hotter than it was when solvent was being evaporated from the clothes.

The relatively sharp rise in temperature of the air flowing through duct 35, signifying substantially complete recovery of the solvent, 'is sensed by the thermal control switch 45 and (as shown in FIGS. 3, 4 and 5 later to be described) its switch arm moves from one position to another thereby opening a previously closed electrical circuit and closing a previously open circuit. As a result of this movement of the switch arm of the thermal control switch 45, valve motor 39 is energized and rotates through a portion of a complete revolution (about 90). As a consequence, the mechanical linkage 38is moved to a corresponding extent and, as a result of this movement, damper 17 is moved to open position and damper 37 is moved to open the exhaust passage 36 and to close 01f the passage through duct 31 into sump 18; in addition, steam-inlet valve 26 and waterinlet valve 39, both of which were open, now close. This is the condition shown in FIG. 2, and is the aerating portion of the cycle. The air flow pathmay now be traced as follows: fresh outside air is pulled, by blower 32, into the housing 11 through air inlet 17 and into the rotating drum through the perforations in its circumferential wall. This fresh air passes through the clothes contained in the drum, out through the perforations in its circumferential wall, down through the slot 20 and into the duct 35. This air is then exhausted by blower 32.

through exhaust duct 36.

The apparatus shown in FIGS. 1 and 2 and described hereinabove is controlled by relays, motors and electrical circuitry the wiring diagram of which is shown in FIGS. 3, 4 and 5 of the present application. FIG. 3 shows the conditions of the relays and switches when the apparatus is on but dormant or quiescent. This is the condition of the machine between the aerating period of a first load and the recovery-of-solvent period of a second load. FIG. 4 shows the condition of the relays and other switches when the apparatus is recovering solvent, as described in connection with FIG. 1. FIG. 5 shows the condition of the relays and switches when the apparatus is aerating, as described in connection with FIG. 2.

Referring now first to FIG. 3, as indicated above, FIG, 3 is a wiring diagram showing the condition of the relays and switches when the apparatus of FIGS. 1 and 2 is dormant or quiescent, which is the condition of the machine following the termination of the aeration period of a first load and prior to the beginning of the recoveryof-solvent operation of a second load. The access door (not shown) is open for unloading and loading, and the arm of switch 15 (associated with the access door) is in the upper position. Manual switches 51 and 52 are in the automatic or closed positions, as shown. Thermal control switch 45 has returned to the position in which its arm is in the down position making contact at B. Fan switch 60 and drive switch 61 are in the closed position. Timer switch arm 55 is closed as shown in FIG. 3. Relays 58 and 59 are deenergized. Relay 57 is in energized condition and fan motor 33 is running due to the complete circuit between power lead L2 and power lead L1 which may be traced from L2 through fan switch 60, fan motor 33 and the coil of relay 5'7 in parallel, door switch '15 in the upper position, lead 65, lead 64, the left switch arm of relay 58 in the down position, and lead 63 to L1. Drive motor 13 is stopped, the circuit therethrough being open at the door switch 15 and at relays 58 and 59. Valve motor 39 is not running and its cam shaft is in such position that arms 70, 71 and 72 are each in the positions shown in FIG. 3. The circuit through contact point 70B is open at relay 58 and at start switch 50. The circuit through contact point 71B is open at relay 59. This is the condition of the circuitry when the access door is open for removing the contents of the drum 10 and reloading.

When the access door is closed, the door switch 15 is moved from position A to position B. As a result, the parallel circuit through fan motor 33 and relay 57 is opened, the fan motor 33 stops, and relay 57 becomes deenergized. Start switch 50 is a spring loaded type of switch having two contacts, an upper and a lower as shown in the drawing. When start switch 50 is pressed to start the automatic cycle, a circuit is completed through the coil of relay 58 by way of the timer switch arm 55. The left and right switch arms of relay 58 move up from the B to the A contact position and a circuit is completed through fan motor 33 and the coil of relay 57 in parallel by way of the fan switch 60, lead 66, the left arm of relay 53 and lead 63. Thus, relay 57 is energized and its contact arm moves to the up position which is in the position shown in FIG. 4. Relay 58 now locks up. The circuit may be traced from L2 through timer switch arm 55, coil of relay 58, the right switch arm of relay 58 in the A position, the switch arm of relay 57, the door switch 15 in the B position, lead 66, the left switch arm of relay 58 in the A position and lead 63.

When st-art switch 50 was depressed to start the automatic cycle, its lower switch arm completed momentarily a circuit through the coil of relay 59 by Way of timer switch arm 55. The relay 59 is, accordingly, energized and the left and right switch arms of relay 59 move to the up position as shown in FIG. 4. Relay 59 then locks up. The circuit may be traced from power lead L2 through the timer switch arm 55, the coil of relay 59, the right arm of relay 59, the left arm of relay 59, the thermal control switch 45 in the B position, the manual switch 52 in the B position, the switch arm of relay 57, the door switch 15, lead 66, the left arm of relay 58 in the A posi tion and the lead 63. Thus as a result of depressing start switch 50 to effect momentary closing-of the upper and lower contacts, relays 5 7, 58 and 59 are each placed in the energized condition.

Fora reason that will become clear upon a reading of the complete description of the present apparatus, at the time that start switch 50 was depressed to initiate the cycle, valve motor 39 was stopped with its cam shaft in such position that switch arms 70, 71 and 72 were in the position shown in FIG. 3. Thus, when relay 59 became energized, a circuit was closed through the valve motor 39 and the B contact of arm 71. The circuit may be traced from the power lead L2 through the valve motor 39, the arm 71 in the B position, leads 76, the left arm of relay 59, the thermal control switch 45 in the B position, the manual switch 52 in the B position, the arm of relay 57, door switch 15 in the B position, lead 66, the left arm of relay 58, and the lead 63. As a result, valve motor 39 is V energized and begins to run. By suitable reduction gearing (not shown) the shaft 81 of the motor 39 is rotated slowly counter-clockwise and switch arms 70, 7&1 and 72 are moved from the position shown in FIG. 3 to the position shown in FIG. 4. The cam arrangement is such that contact is made by switch arm 72 at A before the contact is broken by switch arm 71 at B. Thus, the circuit for energization of the valve motor 39 is switched from lead 76 to lead 80 and valve motor 39 continues to run until the circuit is broken by switch arm 72 at A. When this occurs, switch arm 71 is in contact with A but the circuit through 71A is open at the thermal control switch 45. Thus, valve motor 39 stops after rotating the shaft 81 counter-clockwise through approximately 90.

Returning now momentarily to FIGS. 1 and 2, it will be seen that when the cam shaft of valve motor 39 is rotated counter-clockwise through approximately 90, the linkage 38 is moved by the movement of arm 89 which is secured to and rotates with the shaft 81. Thus, as previously described in connection with FIGS. 1 and 2, the damper 17 is opened, the damper 37 is moved through an angle of approximately 90 to open the exhaust duct 36 to the outside and to close the duct 31 below the sump 18, and the steam-inlet valve 26 and water-inlet valve 30' are closed.

It will be noted from FIG. 4 that during the recoveryof-solvent portion of the cycle, the motor of timer 56 is not running since the circuit therethrough is open at contact B of the auxiliary switch 70 operated by cam 73 secured to shaft 81 of valve motor 39.

It will be noted that when the valve motor 39 stops running as a result of the breaking of the contact at 72A, the recovery portion of the cycle does not terminate. Drive motor 13 continues to drive the drum 10 rotationally, fan motor 33 continues to drive the blower 32, and relays 57, 58 and 59 remain energized. This condition continues until, as a result of the solvent being substantially evaporated from the clothes in drum 10, the temperature of the air passing the thermal control switch' 45 rises sharply. The switch arm of switch 45 then moves from the B to the A position, as shown in FIG. 5. When this occurs, the circuit through relay 59 is broken but a circuit is completed through valve motor 39. This circuit may be traced from the power line L2 through the valve motor 39, the switch arm 71 in position A, lead 79, the arm of thermal control switch 45 in the A position, the arm of switch 52 in the B position, the arm of relay 57, the door switch in the B position, the left arm of relay 58 and the lead 63. For convenience in describing the operation of the combination claimed in the present application, valve motor 39 is assumed to be a well known form of reversible motor. Accordingly, in response to the closing of the circuit just described, the shaft 81 of valve motor 39 rotates clockwise until the switch arm 71 makes contact at B and breaks contact at A. When this occurs, valve motor 39 stops running by reason of the fact that the circuit through 71B and lead 76 is open at the thermal control switch 45 whose arm is now at contact A as shown in FIG. 5.

During the movement of shaft 81 of valve motor 39 just described, the auxiliary switch arm '70 is moved from contact A to contact 13 as shown in FIG. 5 and timer 6 motor 56 is now energized. The circuit may be traced from the power lead L2 through the motor of timer 56, the auxiliary switch 70 in position B, the right arm of relay 58, the arm of relay 57, the door switch 15 in the B position, lead 66, the left arm of relay 58, and the lead 63.

Thus, as described above, the movement of thermal control switch 45 from the B to the A position, in response to the sharp rise in the temperature of the air passing by the control switch 45, actuates valve motor 39 and drives its shaft 81 clockwise through a sufiicient number of degrees (approx. to move the mechanical linkage 38 of FIGS. 1 and 2 to effect opening of the damper 17, movement of the damper 37 through approximately 90 to open the exhaust duct 36 and close off duct 31 from sump 18, and closing of the steam-inlet and water- inlet valves 26, 30. The system is now in the aerating portion of the cycle, the air-flow path of which is shown in FIG. 2, previously described. Timer motor 56 is running, and its shaft is slowly rotating. At the expiration of the preselected time period, which may, for example, be two minutes, the aerating portion of the cycle is terminated by the movement of the timer switch arm 55 to the open position. When this occurs, the circuit through the coil of relay 58 is opened and its switch arms drop. This breaks the circuit through the fan. motor 33, the drive motor 13, and the coil of relay 57, by reason of the open circuit at the left switch arm of relay 58'. Thus, the fan and the drum 10 are both stopped. The timer switch arm 55 returns to its closed position and the system has now returned to the dormant or quiescent condition shown in FIG. 3 and first described above.

It will be seen that I have provided a solvent recovery tumbler having the ability to sense when the solvent is substantially completely removed from the load being processed. Exhaustive laboratory tests have shown that regardless of the temperature of the incoming air, the temperature of the clothes and of the air leaving the recovery tumbler will rise but a very small amount until all the solvent in the clothes has been vaporized. The temperature of the air leaving the recovery tumbler then rises rapidly. Laboratory observations have shown that when the recovery unit is operated with a similar load of garments at the same steam pressure and at a constant cooling water rate and temperature, the rapid rise in temperature begins consistently at the same temperature. The thermal control switch 45 is therefore calibrated to open at a temperature just above the temperature at which this rapid rise begins. a

Following is an example of the temperature conditions which may be involved. The air stream entering the tumbler drum may be 230 F. The air stream leaving the drum at the beginning of the recovery period may be 140 F. As indicated hereinbefore, the temperature of the air stream leaving the drum rises very slowly at first but rises rapidly as the solvent approaches complete recovery. When the temperature reaches say 189 F. percent of the solvent has been recovered, but the temperature of the garments in the drum is still only F. Under such conditions, the thermal control switch 45 would be set to operate at 189 F.

It is to be noted that the manual switch 51 and the selector switch 53, shown in FIGS. 3, 4 and 5, play no part in the operation of the automatic cycle described hereinabove. These switches are used for special cycles when tumbling very fragile garments, and form no part of the present invention.

While the preferred embodiment of this invention has been described in some detail, it will be obvious to one skilled in the art that various modifications may be made without departing from the invention as hereinafter claimed.

Having described my invention, I claim:

1. In a solvent recovery machine having within a housing a perforated rotatable drum for tumbling clothes, garand said condensing unit,

ments and the like which have been prevously cleaned with a solvent such as carbon tetrachloride, trichlorethylene, perchlorethylene and the like; motor drive means for rotating said drum; a closed air-flow path within said housing, said path including a blower for circulating air through said drum and its garment contents, a heating unit having control means adapted to couple said heating unit to a source of heat for heating said air within said housing before it enters said drum, said heating unit being disposed in said housing in the air-flow path between said blower and said drum, a condensing unit having control means adapted to couple said condensing unit to a supply of coolant for condensing the solvent from said air, said condensing unit being disposed in said housing in the air-flow path between said blower and said heating unit, and a single temperature-sensitive switch disposed in said housing in the air-flow path between said drum said temperature-sensitive switch having low-temperature and high-temperature contacts; inlet and exhaust vents adapted when open to communicate with the outside of said housing, said inlet vent being located in the air-flow path between said heating unit and said drum, said exhaust vent being located in the air-flow path between said drum and said condensing unit, each of said vents having a damper therein; a linkage connected to both said dampers and also to both said control means; motor drive means for said linkage, said motor drive means including a shaft; multiple-contact switch means connected electrically to the motor of said last-mentioned motor drive means, the individual contacts of said switch means being adapted to be either open or closed according to the angular position of said shaft; and electrical circuit means connecting said temperaturesensitive switch with at least one set of contacts of said multiple-contact switch means for completing a circuit through said motor when said high-temperature switch contacts close, for actuating said motor to move said linkage to open both said dampers and simultaneously to actuate both said control means to decouple said heating unit from its source of heat and said condensing unit from it supply of coolant.

2. Apparatus as claimed in claim 1 further characterized by the provision of a motor-driven timer switch the motor of which is connected to be actuated in response to the closing of said high-temperature switch contacts; and electrical circuit means connecting the timer switch to tie-energize the drum motor-drive means at the termination of a period of time determined by said timer switch.

References Cited in the file of this patent UNITED STATES PATENTS 2,310,680 Dinley Feb. 9, 1943 2,400,726 Wright et al. May 21, 1946 2,539,407 Dinley Jan. 30, 1951 2,911,810 Lantz et al Nov. 10, 1959'

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