US3250018A - Control arrangement for a dryer - Google Patents

Description

3 M w H: .H: .Hhh H- y 1966 J. D. EDWARDS CONTROL ARRANGEMENT FOR A DRYER Filed NOV. 8 1963 Jameaflfciwczrais' May 10, 1966 J. D. EDWARDS CONTROL ARRANGEMENT FOR A DRYER 4 Sheets-$heet 2 Filed Nov. 8, 1963 .[71U67Lib7"-' jam-6:51p. Edwards May 10, 1966 J. D. EDWARDS CONTROL ARRANGEMENT FOR A DRYER 4 Sheets-Sheet 5 Filed Nov. 8, 1965 May 10, 1966 J. D. EDWARDS CONTROL ARRANGEMENT FOR A DRYER 4 Sheets-Sheet 4.

Filed Nov. 8, 1965 Ira/6712 5): finzesfl Eda/c2 71215 j W J@ United States Patent 3,250,018 CONTROL ARRANGEMENT FOR A DRYER James D. Edwards, Eflingham, Ill., assignor to Borg- Warner Corporation, Chicago, 111., a corporation of Illinois Filed Nov. 8, 1963, Ser. No. 322,385 1 Claim. (Cl. 34-45) This invention relates to fabric-drying machines and more particularly to fabric-dryness sensing or detecting arrangements for such machines.

Presently known fabric-drying machines employ moisture-sensing devices for automatically controlling the drying cycle by continually measuring the moisture content of fabrics as the fabrics are dried. Such devices operate on the principle of the difference in electrical resistance between the wet and dry states of the fabrics. In the adaptation of such devices to the machines, the moisturesensing system is installed in a rotatable fabric container of the machine and is instrumental in continually sensing the degree of moisture of the clothes and transmitting their condition to a control unit. When the fabrics are completely dry or reach a predetermined selected degree of dryness, the control unit is effective to discontinue the dryness operation of the machine.

Moisture-sensing devices have included electrical conductors positioned within the fabric container of the machines and bridged by the wet fabrics, which thereby complete electric circuits to energize a basket-rotating and fan-operating motor and also to energize an electric heating coil or coils, or a solenoid to effect operation of a gas burner. These electrical conductors have been placed on the fabric-tumbling bafiles of the container so that the various fabrics engage and then fall away from the conductors on the baffies during rotation of the container.

An object of the invention is to provide a new and improved fabric-dryness detecting or sensing arrangement in which recognition is given to the fact that more effective and complete control of the moisture-sensing of the fabrics can be obtained by providing substantially greater fabric-contacting areas of the electrical conductors during rotation of the fabric-container.

Another object of the invention is to provide a new and improved fabric-dryness detecting or sensing arrangement in which the electrical conductors are provided in strip form and arranged in and supported by the fabric container in parallel relation to each other between adjacent baffies of the container, the strips extending circumferentially of the container in spaced re lation to each other along the rotational axis of the container so that a considerable area of each strip is contacted by the fabrics during rotation of the container.

Other objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings in which a preferred embodiment of the invention is disclosed.

In the drawings:

FIG. 1 is a vertical sectional view of a fabric-drying machine illustrating the disposition of the new and improved fabric-dryness detecting or sensing conductors in the fabric-container;

FIG. 2 is a transverse sectional View of the fabric container of FIG. 1, taken on line 2-2 of FIG. 1;

FIG. 3 is a greatly enlarged axial sectional view showing details of the fabric-container mounting and also a collector ring structure incorporated therein;

FIG. 4 is a longitudinal sectional view of one of the conductors of FIGS. 1 and 2 and illustrating its attachrnent to a portion of the container, taken on line 4-4 of FIG. 1;

3,250,018 Patented May 10, 1966 FIG. 5 is a face view of the conductor shown in'FIG. 4; FIG. 6 is a transverse sectional view of the conductor and container portion shown in FIGS. 4 and 5, taken on line 66 of FIG. 4;

FIG. 7 is a transverse sectional view of another condoctor and its attachment to a portion of the container, taken on line 77 of FIG. 1;

FIG. 8 is a transverse sectional view of a fabric container and illustrating a modification of the fabric-dryness detecting or sensing conductor arrangement;

FIG. 9 is a face view of the sensing conductor shown in FIG. 8;

FIG. 10 is a side view of the sensing conductor of FIGS. 8 and 9;

FIG. 11 is a section taken on line 11-11 of FIG. 9;

FIG. 12 is a section taken on line 12- 12 of FIG. 8; and

FIG. 13 is a schematic electric diagram of a control arrangement embodying sensing conductor arrangements of the invention.

Referring to the drawings and particularly to FIG. 1, the invention is incorporated in a fabric-drying machine, which may be in the form of a domestic type clothes dryer as shown and described in detail in US. Patent No. 2,798,307, issued July 9, 1957, to A. L. Reiter. More particularly, the clothes dryer comprises a cabinet A, a clothes container or drum B within the cabinet A and rotatable about a substantially horizontal axis and operative to tumble the fabrics disposed therein; an air moving fan assembly C axially disposed with respect to the drum B and effective to cause a large volume of air to pass through the drum B; a driving mechanism assembly D to rotate the drum B and the air moving fan assembly C; an air heating structure F over and through which ambient air is drawn by the fan assembly C to heat the air before entry into the drum to more effectively absorb moisture in the fabrics contained in the drum B; an air discharge port H; and a supporting structure I for the operating mechanism disposed in the cabinet and including support means for the driving assembly D.

The cabinet A is provided with a hinged door 10 providing access to the drum for inserting moisture-laden clothing into the drum and for removal of dried clothing from the drum.

The supporting structure I comprises a base formed of sheet steel members indicated in their entirety at 11 and suitably formed and interconnected to define a substantially box-like base, and a superstructure formed of bent sheet steel member 12 arranged vertically to provide a supporting structure for portions of the driving mechanism assembly D and the air heating assembly F.

The drum B comprises a cylindrical metal shell 13 formed of an imperforate piece of sheet steel, and having a forward drum end 14 secured to the front end of the shell 13 and a portion of which is bent over the shell 13 to provide a tire 15.

The drum is further provided with a rear wall 16 having a central opening 17 defined by an inturned flange 18. The rear wall 16 of the drum has secured thereto an imperforate radial wall 19, said radial wall being spaced from said rear wall and being provided with a peripheral wall portion. The rear wall 16, the radial wall 19, and the peripheral wall portion forming a chamber 20 for housing the fan C. The cylinder is rotated in a counterclockwise direction at about 45 rpm. and the fan is rotated in a clockwise direction at about 600 rpm. The air, moved by the fan C, moves in a direction opposite the direction of rotation of the drum and is discharged into the drum. This action provides an effective air movement through the drum. Three baffies 21 are provided on and are circumferentially equi-distantly spaced about the interior cylindrical surface of the drum and these baflies extend in directions parallel to the axis of rotation of the drum to tumble the clothes during circulation of heated air through the drum.

. The rear end of the drum B is provided with conicallyshaped depressed portions 22 providing a mounting means for a hub 23 which is secured to the conically-shaped portions 22 by bolts, as shown in FIG. 3. The hub 23 is provided with a central through aperture 24 adapted to receive a driven shaft 25 having an axially-extending groove 26 disposed on the periphery thereof, said groove being adapted to receive an end portion of a set screw 28 received into a threaded aperture 29 in said hub, thereby maintaining said shaft in fixed relationship with respect to the hub which is carried in fixed relationship with respect to the conical-shaped portions forming a part of the rear wall of the drum B.

The driving mechanism assembly D is operable to cause rotation of the drum B and to drive the air. moving fan assembly C. The driving mechanism assembly D comprises, in general, spaced wheels one of which is shown at 30 (FIG. 1) and as having a shaft 31 suitably journalled in and carried by the support plate 11 of the supporting structure I. The periphery of each wheel is in intimate engagement with the tire 15. The assembly D comprises the driven shaft 25, a drive pulley 32 mounted on a shaft 31 remotely from wheel 30, a drive pulley 34 rotatably mounted on the driven shaft 25 for relative rotation therebetween, a motor driven drive pulley (not shown), and an endless V-belt 38 suitably mounted on the drive pulleys 32 and 34, and the motor-driven pulley.

FIG. 2 is an enlarged view of portions of the driving mechanism assembly D. It can be seen that the shaft 25 wheel 30 to drive the drum to effectively tumble the fabrics contained therein. The rear end of the drum is supported by the centrally disposed shaft journalled in the bearing 41, and, as the shaft is fixedly secured to the drum B, it will rotate therewith and act as a driven shaft, and, accordingly, rotation of the drum being accomplished by rotation of the wheel 30.

As the driving mechanism for the drum B is interrelated with the driving mechanism of the air moving fan assembly C, it can be seen that, when the drum rotates, the air moving fan assembly will also be operative. Movement of the V-belt 38 will cause rotative movement of the pulley 34 and because the pulley is secured to the hub 58 which in turn carries annular fan blade support 60, the air moving fan assembly C will be caused to rotate.

The air heating assembly F comprises, in general, a housing 63 formed of metal plates to define the shape as shown and to provide a bafiie 64,whereby to control the flow of ambient air for passage over and through an electric heating element 65 suitably carried in a sheet metal frame 66 which is attached to the vertical support 12, the

7 sheet metal frame being formed to define a tunnel-like is fixedly secured to the drum B and is rotatable therewith by means of the set screw 28 disposed in the hub 23 which is carried by portions of the rear wall of the drum B. Carried by the vertical support 12 is a bracket 40 adapted to support a sintered powdered metal bearing 41 in which outer end portion 42 of the shaft 25 is effectively journalled. In order to prevent relative axial movement of the shaft 25 with respect to the bearing 41 there is provided a washer 43, and a snap ring 44 disposed in a groove 45 in the shaft portion 42.

The air moving fan assembly C is mounted upon the shaft 25 for relative rotation therebetween. The shaft 25 rotates in one direction while the fan assembly C rotates in the opposite direction; In order to accomplish this feature, a bronze bearing 46 is provided having a rubber sleeve 47 engaging the cylindrical sleeve portion 48 of a drive pulley hub 58. vided a second bronze bearing 49 having a rubber sleeve 50 engaging hub 58. The bearings 46 and 49 are disposed in spaced relationship. Surrounding the shaft 25, in the space between the bearings, there is disposed an oilsoaked wick felt '52. Adjacent the'end portions of the bearings there is disposed a felt seal maintained in its proper position as shown by a snap ring 56 in a groove in shaft 25 and which ring is encased in a housing 57 and operable to effectively prevent lubrication from running axially along and outwardly of said shaft 25.

The drive pulley 34 is mounted on the hub 58 by bolt and nut assemblies 59 which also secure, to the hub 58, an annular fan blade support 60 having attached thereto, adjacent the periphery thereof projecting blades 61. The hub 58 is suitably journalled on the shaft 25 by the bearings 46 and 49.

The drum B is supported for rotation on the spaced wheels 30, the peripheries of which are in engagement with the tire 15 so that the drum B may effectively rotate thereon. One of the wheels is an idler wheel and is not driven by the driving means but merely acts as a support for the drum B. However, the wheel, shown at 30, is driven through the shaft 31 by the V-belt 38 and pulley 32 which in turn is rotated by a motor-driven pulley. Accordingly, the drum is caused to rotate by rotation of the In like manner, there is also proshape with the electric heating element 65 disposed therein. Ambient air is drawn by the air moving fan assembly C through a plurality of apertures as at 67 disposed in the rear enclosure panel 68 and also through the opening 69 in the upper regions of the cabinet for passage into the housing 63 and through the tunnel-like shaped enclosure 66 for contact with the heating element and thereafter through an aperture 70 in the vertical support 12. The ambient air, coming in contact with the heating elements, will be raised in temperature for effectively absorbing the moisture contained in the fabrics disposed in the drum. Although an electric heating element is disclosed herein, it is obvious that other means may be employed for air heating, such as, for example, a gas burner having an electrically controlled device for controlling the flow of gas and ignition of the gas.

The air-moving fan assembly indicated in its entirety by the letter C is disposed axially of the drum and is of a relatively large size to provide an unusually large volume of air for passage through the drum B for contact with the moisture-laden clothes disposed therein, whereby to absorb the moisture contained in the clothes and to carry the same outwardly of the drum and the cabinet through the vent opening H. The air-moving fan assembly C comprises the annular support 60 having fixedly disposed adjacent the periphery thereof a plurality of fan blades 61 in equally spaced relationship and disposed in the chamber 20 defined by the rear end Wall assembly of the drum B. Rotation of the fan assembly C will cause ambient air to be drawn through the apertures 67 in the back panel 68 and through the opening 69 in the upper regions of the cabinet for passage through the housing 64 and the tunnellike shaped enclosure 66 for contact with the air heating element, through the opening 70 in the vertical support 12 and through the annular opening 17 in the rear wall 16 of the drum B for contact with the fabrics in the drum B where the air will absorb moisture contained in the fabrics and will be forced outwardly from the drum through the openings 71 in the flange 72 at the forward end of the drum for discharge into an air chamber 73 for transmittal to the lower regions of the cabinet and thereafter outwardly from the cabinet through vent opening H.

The present invention is directed particularly to a fabricdryness control arrangement of the direct fabric-moisture sensing control type operating on the principle that the electrical resistanceof a fabric varies as the moisture content varies and having means for measuring the resistance of the fabric from its initial maximum moisture content to a predetermined minimum moisture content. It is known that electrical conductors have been placed on the fabric-tumbling baffles of dryer drums to contact the moisture-laden fabrics in the adaptation of this type of control to dryers. However, the conductors on baffles provide a relatively small area in intermittent contact with the fabrics and, accordingly, moisture content of the fabrics may not be accurately determinable by the control system.

In the design of the present control system, a substantially larger area of electrical conductors is provided for contacting the moisture-laden fabrics so that greater accuracy and eflicieney can be obtained in the moisture content measurement of the fabrics. In this system, it has been recognized that the battles are necessary and effective in insuring tumbling of the fabrics, not only to speed up the drying process during heated air circulation, but to expose different portions of the fabrics for contact with the electrical conductors.

More particularly, the control system contemplates the usage of a considerably large area of the inner cylindrical surface of the fabric-tumbling drum for coverage by the electrical conductors and in a manner that insures contact of a substantially largeramount of the fabrics with the conductors at all times so that the control system can function with greater accuracy and reliability.

Referring to the drawings, the steel cylindrical drum or fabric-container B has electrically-insulating coatings 76 and 77, such as porcelain, covering substantially the entire inner and outer surfaces of the cylindrical wall 13 and completely covering the inwardly projecting baflies 21 thereof. The electrical conductor assemblies of the moisture-sensing control arrangement are indicated at 78 and 79 and are arranged in pairs with the assemblies of each pair being disposed in parallel relation between baffles 21 of the container, each assembly being curved 'to conform to the inner cylindrical surface of the drum B and extending circumferentially thereof. As seen in FIGS. 1 and 2, there are three pairs of assemblies 78 and 79 with each pair being spaced from the other pairs circumferentially of the drum and disposed and extending between baffles 21. Each assembly 78 comprises a nickel-silver plated copper conductor blade 80 and each conductor assembly 79 also comprises a metallically-simular conductor blade 81, the blade of each assembly being substantially coextensive with its assembly and exposed to the moisture-laden fabrics tumbled in the drum. It will be apparent that the considerable contact area of the blades with such fabrics in the drum will permit accurate and reliable sensing and measurement of the moisture content of the fabrics.

Referring to FIGS. 4, 5, 6, and 7, the conductor blades 80 and 81 of each pair of assemblies 78 and 79. are

mounted on the porcelainized cylindrical drum inner surface to provide a portion of an electrical circuit. For this purpose, the blade 80 is adapted to receive electrical current through a collector ring structure generally indicated at S in FIGS. 1 and 3 and to be later described. The current is transmitted to and through the positive contact blade 80 and the moisture-laden fabrics to the contact blade 81 grounded to the steelcylindrical wall 13 of the drum. As the fabrics are dried by the heated air circulated through the fabrics in the drum, the moisture content of the fabrics steadily decreases until such time as the electrical resistance of the fabrics increases sufiiciently to interrupt the circuit.

The attachment of the assembly 80 to the drum is shown in FIG. 6. As previously described, the steel drum has its inner and outer cylindrical surfaces provided with electrical-insulating procelain coatings 76 and 77. posed between and engaging the inner cylindrical surface of the drum and contact blade 80 is an electrical insulating strip 82 of any suitable material, the strip 82 being of greater area than the blade. The blade 80 and strip 82 Dis-' and engages the bushing, the bushing 88 will be urged against the insulating strip 82. It will be evident that the nut 90 and bolt 83 securely holds the blade 86, strip 82, and bushing 88 in assembled relation with the drum. An electricity-conducting wire 91 is encased in a rubber or plastic covering, but has its bare end wrapped around the bolt 83 of one of the nut and bolt units and secured thereto by .a nut 92 threaded onto the bolt so that current can flow through thebolt 83 to the blade 80.

The blade 81 is attached to the drum B by a plurality of nut and bolt units each having the head 93 of a copper or steel bolt 94 brazed to the blade 81 and received within an opening 95 of an insulating strip 96, the threaded portion 97 of the bolt extending through an opening 98 in.

the cylindrical wall of the drum and having a nut 99 engaging a steel lock washer 100 sea-ted against a small porcelain-free metal area 10 1 of the drum, the nut being operative to firmly engage the washer with the drum to provide electrical grounding by the drum and to connect the blade 95 and strip 96 to the drum.

The electrical current is conducted to the blades 80 of each pair of the conductor assemblies by the wires 91 which extend in an axial direction along the cylindrical wall 13 of the drum and toward the rear wall 16 of the drum, the wires being collected in and connected electrically to each other and to a Wire conductor in an insulated sheath 102 passing through a rubber grommet 10'3 positioned in the wall 13 and through a radially-extending conduit portion 104 of the rear wall of the drum and into and through an axial bore 105 of the driven shaft 25. The terminal end of the sheathed wire conductor is soldered to a brass collector plug 106 positioned within an insulated nylon bushing 107 pressfitted into the outer end of the bore 105 of the shaft 25. The plug 106 receives electric current from an L-shaped brass pick-up element 108 having one of its arms provided with a curved end portion 109 engaging the plug and its other arm secured to a nylon bushing 110 fixed to the bracket 40. Current is conducted to the pick-up element by a wire 111.

\FIG. 13 illustrates a simple schematic electrical diagram of a dryer control embodying the three pairs of conductor blades 80 and 81. In general, a motor M is operative to rotate the drum and fan in the manner previously described and is arranged in series circuit relation to the blades 80 and 81 and the winding of a relay R. Upon closing the line switch LS, current flows from a source of electric power, connected to the line L1, through conductor 01 and to the windings of the motor M to energize the motor. BetWeen conductor 02,- connected to the motor windings, and conductor C3, the three pairs of conductor blades are arranged in parallel circuit relation. Moistureladen fabric indicated at MLF is shown positioned in bridging relation to one pair of the blades 80 and 81 and, accordingly, current is conducted by the fabric moisture from blade 80 to the blade 81 and thence, through conductor C6, to the winding of relay R and line L2. Energiz-ation-of relay R causes closing of its switch RS to establish a circuit to energize the heating coil 65. It will be apparent that, the circuit to the motor M and heating coil 65 is dependent on the flow of current through the moisture-laden fabric which, in tumbling during rotation of the drum, is effective to have bridging contact with the blades of successive circumferentially positioned pairs. Accordingly, upon removal of a predetermined amount of moisture from the fabrics in the drying operation, the

' fabrics will not conduct current between the contacted are connected to the drum by a plurality of nut and bolt units, each comprising a copper bolt 83 having its head 84 secured, as by brazing, to the blade 80 and having its threaded portion 85 received within aligned openings 86 and 87 in the strip 82 and an annular insulating bushing 88. The bushing 86 is disposed within an opening 89 in the wall 13,.the opening being of greater diameter than the opening 86 so that when nut 90 is threaded on the bolt .shown in FIGS. 9, 10, and 11.

blades with the result, the circuit will be interrupted and operation of the dryer will be terminated.

In the modification illustrated in FIGS. 8-12, inclusive, the control arrangement may embody one or more spaced electrical conductor assemblies 112. The conductor assembly is in the form of a ring extending circumferentially of, and connected to, the porcelainized cylindrical inner surface of the drum 13a. The assembly 112 per se is FIGS. 8 and 12 illustrate the assembly 112 attached to the drum. The assembly 112 comprises a thin aluminum band or base 113; a band 114 formed of insulating material, such as thick phenolic Dacron; the bands 113 and 1 14 being substantially co-ex tensive with but extend beyond the ends of elongate electric conductors 115 and 116, the conductor 115 being in the form of a single strip positioned between and surrounded by the parallel extending side and end strips of the electrical conductor 1 16. The conductors 115 and 116 are preferably formed of nickel-silver plated copper. The conductors are located on one side of the insulating band 114, and the aluminum band 113 is disposed on the other side of the band 114, the conductors and band 113 being securely mounted on the insulating band by any suitable adhesive material.

The aluminum band 113 is formed with a plurality of spaced angularly offset flanges 117 in staggered relation on opposite side edges thereof receivable within slots 118 in the cylindrical wall of the drum and bent over to engage the outer cylindrical surface of the drum to insure retention of the conductor assembly 112 on the drum.

As seen in FIGS. 8 and 9 and 11, the drum 13a and the aluminum band 113 are provided with aligned circular openings and O for receiving a nickel-silver plated copper tab 119 spaced from the edges of the openings O and O. A brass rivet 120 extends through the tab 119, the insulating band 114 and one end of the conductor strip 115 to secure the tab to the band 114 and to. the strip 115 and in electricity-conducting relation to the strip 115. A brass rivet 121 extends through the transverse end portion of the conductor strip 116, the aluminum band 113 and an electricity-conducting nickelsilver plated copper tab 122. The tab 119 projects through the opening 0' of the drum and exteriorly thereof as shown in FIG. 8. The tab 122 extends through a slot 123 in the cylindrical wall of the drum and exteriorly thereof and is bent over to engage a porcelain-free steel surface of the drum to provide grounding of the electric circuit. The tab 119 is soldered to a conductor Wire, such as 102a, receiving current through the collector ring structure.

As shown in FIG. 8, the conductor assembly extends circumferentially of, engages the inner cylindrical surface of the drum, and extends through circumferentially aligned depressions 124 in the angularly inclined walls of each baffle 21, the depressions 124 being formed in the foot portions of the baffie walls, welded to the drum, so that the depressions are adjacent to the inner cylindrical surface of the drum. The conductor assembly is retained in assembled relation and insulated from the steel bafiles by providing thin sheets 125 of insulation material disposed between the bafiles and the conductors 115 and 116 so that the sheets 125 prevent engagement of the metal of the baffles with the conductor strips 115 and 116.

It will be apparent that moisture-laden fabrics contacting the conductor strips 115 and 116 will complete an electrical circuit (FIG. 13) and, when the moisture has been substantially removed from the fabrics, the circuit will be interrupted.

While there have been illustrated preferred embodiments of the invention, many modifications may be made without departing from the spirit of the invention, and, accordingly, the invention is not to be limited to the details of construction set forth but contemplates coverage of all changes within the scope of the appended claim.

i What is claimed is:

In a fabric dryer, a casing; a cylindrical fabric-containing porcelain-coated metal drum having first and second parallel rows of circumferentially spaced openings therein and aplurality of bafiles circumferentially spaced about and supported on the inner cylindrical surface of said drum; means for mounting said drum in said casing for rotation about a generally horizontal axis; means for heating the air in said drum; means for circulating the heated air through said drum; the improvement residing in means for electrically controlling operation of said air-heating means and including an electric circuit having spaced first and second electrical conductors in said drum, first and second electrical-insulation strips on the inner cylindrical surface of said drum and disposed between said first strip having openings, aligned with and smaller than the aligned openings'of said first row in said drum -and said second strip having openings, larger than the aligned openings of said second row in said drum, said conductors and strips extending circumferentially of said drum and between and in spaced relation to said bafiles, spaced electricity-conducting members connected to said first conductor and extending through said openings in said drum and said strips and exteriorly of said drum, electrical-insulation bushings within the openings of said first row in said drum and engaging said first strip, means disposed exteriorly of said drum and engaging said members and said bushings securing said first conductor to said drum and connecting said first conductor to a source of electric power, spaced electricity-conducting elements connected to said second conductor and extending through openings in said drum and exteriorly thereof, metal washers on said elements and engaging the metal of said drum, means engaging said elements and said washer and securing said second conductor to said drum and in circuitgrounding relation with said drum, said conductors being adapted to be bridged by moisture-laden fabrics in said drum to complete said circuit.

References Cited by the Examiner UNITED STATES PATENTS 2,798,307 7/1957 Reiter 34-133 3,122,426 2/1964 Horecky 3448 X 3,186,105 6/1965 Nye et a1. 34-45 3,200,511 8/1965 Smith 3445 FOREIGN PATENTS 1,309,566 10/1962 France.

953,748 5/1964 Great Britain.

WILLIAM F. ODEA, Primary Examiner.

JOHN J. CAMBY, Examiner.

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