US2648284A

US2648284A - Motor suspension for oil burners and the like

Info

Publication number: US2648284A
Application number: US118313A
Authority: US
Inventors: Reginald W Beckett
Original assignee: Individual
Current assignee: Individual
Priority date: 1947-08-07
Filing date: 1949-09-28
Publication date: 1953-08-11
Anticipated expiration: 1970-08-11

Description

Aug. 11, 1953 RI w. BECKETT MOTOR SUSPENSION FOR OIL BURNERS AND THE LIKE 2 Sheets-Sheet l Original Filed Aug. 7 1947 v INVENTOR. Reginald W Beckett BY zi'mwv am ATTORNEYS A g- 1953 R. w. B ECKETT MOTOR SUSPENSION FOR OIL BURNERS AND THE LIKE Original Filed Aug. 7, 1947 2 Sheets-+Shest 2 INVENTOR. lnald WBeckctt Reg ATTORNEYS Patented Aug. 11, 1953 MOTOR SUSPENSION FOR OIL BURNERS AND THE LIKE Reginald W. Beckett, Elyria, Ohio Original application August 7, 1947, Serial No.

Divided and this application September 28, 1949, Serial No. 118,313

15 Claims.

This invention relates to fuel burning heating devices and has particular reference to oil burners of the pressure atomizing type in which fuel oil is discharged under pressure through a small orifice or nozzle into a combustion chamber and is burned While suspended in the combustion air that is supplied by a power driven fan. The present application is a division of my copending application for patent, Serial No. 766,967, filed August 7, 1947, now Patent No. 2,506,192, issued May 2, 1950, for Oil Burner.

Oil burners and related devices of the type in- Volved in the present invention have been highly developed and are presently in common use in large numbers. It is desirable, however, to reduce the cost of manufacture of such devices so as to make them more readily available to the public at large. Other improvements sought are along the lines of greater safety, efficiency, and quieter operation,

It is therefore one of the principal objects of the present invention to provide a generally improved motor and fuel pump suspension in which numerous advantageous features of construction and arrangements of parts have been incorporated to obtain economic manufacture and operation, relatively silent operation, and safety.

Economy is obtained by unique design features which facilitate assembly with a minimum of machining of parts and without special skill or the necessity for the use of special tools, lies, and fixtures. Reduced cost is also obtained by the elimination of parts to simplify design and installation.

Noise reduction during operation of the burner is obtained through an improved mounting means for supportin the so-called power unit of the burner, which comprises the electric drive motor and the fan and the fuel Pump actuated thereby. Additional noise reduction is obtained through the provision of a balanced structure so supported as to minimize vibration and oscillation during operation.

Other objects and advantages will become apparent from the following detailed description of a burner embodying the principles of the present invention, such description being made in connection with the accompanying drawings forming a part of this specification.

In the drawings:

Figure 1 is a side elevational view partly in section and with parts broken away and removed showing the oil burner structure;

Fig. 2 is a fragmentary detail view partly in section and with parts broken away taken through the bell-shaped member which mounts the fuel pump on the end of the electric drive motor;

Fig. 3 is a transverse sectional detail taken substantially on the line 33 of Fig. 1, parts of the burner being broken away and removed; and

Fig. 4 is a transverse sectional detail taken substantially on the line 44 of Fig. 1.

General arrangement The present invention relates generally to fuel burning devices of the type disclosed in my prior Patent No. 2,310,274 and the patents referred to therein. Referring now to the drawings by numerals of reference which indicate like parts throughout the several views, the burner is seen to comprise an upright housing structure having spaced substantially parallel front and rear walls i and 2 respectively, substantially parallel side walls, one of which is indicated at 4, and a curved top wall 5. The housing is of cast metal such as iron or aluminum and includes a bottom 6 which is integral with the front and rear walls.

The housing is supported on a pedestal structure which comprises a cast metal base 1 and one or more supporting or spacing blocks or shells 8 and 9.

In each corner of the spacing shell is an integral column which projects below the level of the bottom edges ll of the shell so as to provide dependin foot portions I2 received in mating recesses formed in the top of the base 1 or in the top of the next lower spacing shell. The foot portions of the columns of the spacing shell 8 bear on the upper ends l5 of the columns of the spacing shell 9. The base 1 is formed with thick sectioned bosses I! having flat tops recessed below the level of the square top of the base to serve as footings for the spacing shell columns.

The upper shell 8 differs slightly from the spacing shell 9 in that lugs l8 thereof extend upwardly above the level of the top edges of the shell and interfit in mating recesses formed in the corners of a square socket in the bottom 6 of the housing.

The housing is secured to the base by a vertical stud or through bolt IS the upper end of which is threadedly secured in the housing bottom ii and the lower end of which extends downwardly through and is centered in an opening in platform portion 20 of the case. A nut 2| is tightened against the underside of the base platform to hold the assembly together.

Power unit An electric motor 22 supplies the energy for driving squirrel cage fan or sirocco type blower 23 which is received in a chamber formed in the upper portion of the housing. The fan, inserted into the blower chamber through a large diameter opening 3! provided in the rear wall 2 of the housing, is secured on one end 25 (Fig. 1) of the motor shaft.

Motor shaft portion 2% (Fig. 2) which projects from the other or flat ill of the motor is sur- 60 rounded by a bell-shaped support member 28 that is secured to the motor end 21 by diametrically located cap screws, one of which is indicated at 28. The bell member 28 is formed with an offset circular flange 30 which embraces the motor end 21 and provides a circumferentially extending internal shoulder against which the motor end is seated and located.

The small end of the bell member 28 is formed with a centrally located integral cylindrical sleeve 32 having an internal cylindrical bore 33 that is substantially co-axial to the rotational axis of the motor shaft. Received within the bore or socket 33 is a mating cylindrical plug member 34 formed on a fuel oil pump 35.

The pump plug 34 contains a central journal for pump shaft 36 which is thus disposed in end to end co-axial relation to the motor shaft end 26. A flexible drive coupling connects the shaft ends, one coupling part 3'! being secured by a set screw on the motor shaft end 26 and another coupling part 38 being secured, also by a set screw, on pump shaft 36. A resilient deformable element 39 is interposed between the

coupling parts

31 and 38 to transmit the torque while providing for slight misalignment or displacement of the shafts. One or more set screws 40 threaded through the bell sleeve 32 are engaged in detents in the pump plug 34 to lock the latter in the bell member sleeve and to retain the pump in pre-determined upright position.

The motor 22, together with the fan 23 and the pump 35 secured on opposite ends thereof, are collectively referred to and comprise a removable power unit. This unit operates the oil burner, the pump feeding oil under pressure and the fan supplying combustion air. It is therefore extremely desirable to be able to replace the power unit should a failure occur in either the pump fan or motor so that the oil burner can be continued in service with a minimum of delay or interruption.

Resilient suspension The present invention is chiefly concerned with a unique suspension means for the power unit. A bracket 42 having a transversely curved body portion 43 is concave on its underside so as to fit over and partially embrace the top of the motor. The body of the bracket is generally concentric to the curvature of the motor, the latter being suspended in spaced relation underneath the bracket as will later appear. At one end of the curved body 43 the bracket is for-med with an integral depending flange 44 which is disposed flatwise against the rear wall 2 cf the housing structure and is secured to the latter over the opening 31 by cap screws 45. The bracket flange 44 thus closes the relatively large rear opening in the housing wall 2 through which the fan 23 is inserted into the fan chamber 24, the bracket flange having a relatively small opening 46 which closely surrounds the motor shaft end 25.

Along opposite sides of the bracket at the lower edges of the arcuate or curved body 43 are horizontal portions or lateral extensions 41 which terminate in depending flanges 48. Rubber tension type suspension members 50 are secured by bolts 5| to the underside of the lateral bracket extensions at the front and rear ends of the latter, the bolts being threaded into metal elements embedded in the rubber of the suspension members.

One pair of the resilient rubber members 50 are attached by bolts 52 to

half straps

53 and 54 which cooperatively embrace the motor 22, the bolts 52 passing through radial cars 55 on the ends of the half straps, and being threaded into metal elements embedded in the rubber of the suspension members. The half strap 53 passes over the top of the forward portion of the motor and is disposed underneath the curved body portion 43 of the bracket, while the half strap 54 extends underneath the forward portion of the motor to support the latter. The bolts 52 draw the half straps tightly about the frame of the motor so as to clamp the motor in place and prevent longitudinal movement thereof. The other pair of the resilient rubber suspension members 50, which depend from portions of the bracket extensions 41 that project rearwardly of the curved body portion 43 of the bracket, are secured by bolts 56, threaded into embedded metal elements, to diametrically disposed integral ears 5'! which extend outwardly from opposite sides of the bell-shaped support member 28.

Thus the power unit is resiliently suspended from the bracket 42 by a plurality of resilient rubber members in tension. Extremely quiet burner operation results from this type of mount and the attachment of the resilient elements 53 to different zones along the length of the motor minimizes lateral displacement of the motor andserves to hold the motor in pre-determined relative position with respect to the burner housing structure.

In manufacturing the burner, the motor, bell member, pump and fan are assembled together on the bracket 42 on this sub-assembly is then mounted as a unit on the housing simply by insorting the fan into the chamber 24 through the opening 3| in the housing wall 2 and securing the bracket flange 44 in place by the cap screws 45. The arrangement of the power unit and the attaching bracket as a sub-assembly facilitates economical mass production, the parts being interchangeable, and also permits replacement of the power unit in the field should it become desirable to retain the burner in continuous service while repairs are being made on the motor or fuel pump.

Air induction and control Air is drawn into the fan chamber through a tapered opening formed in the front wall I of the housing. Disposed against the outside of the front wall I of the housing and over the air inlet opening into the fan chamber so as to control the flow of air through such opening, is a hood which may be of cast metal.

The bottom of the hood is open to permit the inflow of air under the control of a sheet metal gate pivotally mounted off center for turning movement about a horizontal axis. The gate is supported on pins 66 that are threaded through aligned openings in bottom portions of the hood side walls, the pins being held against turning by lock nuts 61. The gate is moved upwardly to open position by inflowing air.

The rear edges of the hood are directed toward an integral outstanding rib '69 which is formed on or characters the front wall I of the housing and has the same contour or outline shape as the edges of the hood walls. The hood is spaced from the housing rib 69 by three integral bosses or raised portions, one of which is indicated at 10. Cap screws or bolts 12 pass through openings in ears 13 provided one on each side of the hood and are threaded into the front wall I of. the housing. A clearance 14 is provided between the edges of the hood walls and the rib 69 on the front wall l of the housing.

In adjusting the burner for different oil rates the quantity of combustion .air drawn into the fan chamber through the opening in the bottom of the hood 60 is regulated by controlling the extent to which .the gate opens. The air inlet controlgate is adjusted While the burner is in operation as by means of a rod which extends vertically through the interior of the hood.

To facilitate the turning of the control rod in adjusting the air induction system of the burner a knurled thumb wheel 80 is threaded onto the top of the rod above the top wall .of the hood and is held against turning on the rod by lock inut 8|.

Below the air induction hood 60 an elongated tapered tube 88 of circular cross section is attached by bolts, one of which is indicated .at 81, to the front wall I of the housing structure over an opening which communicates with an air passage formed in the housing structure below the fan chamber. Combustion supporting air drawn into the housing through the hood 16B is forced by the fan 23 down into the air chamber in the bottom of the housing and thence out through the circular passage in the air tube 85 and through a burner head 96 which extends through the walls of the fire box of the combustion chamber, not shown.

Fuel .oil atomization and electrical ignition Fuel oil from a source not shown is supplied by the pump 35 and forced from the latter through a bendable conduit 88 to a rigid conduit 89 supported by a bracket 9| in the center of the air tube 86. Forwardly of the bracket c! the fuel conduit 89 carries a spider 93 that locates the conduit in the center of the air tube. A hollow manifold S54 threaded on the end of the conduit 89 mounts a nozzle 95 to project fuel forwardly through the open mouth of the burner head 90 of the combustion chamber.

The sparking ends of ignition electrodes, one of which is shown at 96, are received through pairs of spaced insulators 91 supported by clamps 98 on the rigid fuel conduit 89. Electrical current for energizing the ignition spark across the ends of the electrodes 95 is supplied by a transformer lllfl normally disposed across an opening through the rear wall 2 of the housing structure. The transformer serves .as a closure for the opening in the rear wall and the electrodes 96 carry contact elements that automatically make electrical connection between the electrodes and the transformer terminals when the transformer is swung to closed position across the housing opening.

The bendable conduit 88 extends through a lateral extension of the rear opening in the housing structure to one side of the transformer I and is disconnected from the fuel pump 35 when it is desired to remove the power unit or the fuel conduit and ignition electrode assembly from the burner. A base portion ill! on the bracket 9| is apertured to receive an upstanding bolt 102 that extends upwardly through a hole in the bottom 6 of the burner housing. A nut I03 on the bolt m2 is tightened down against the base lill of the bracket to secure the latter in place, the bolt having a square or non-circular head I04 that is received in a mating recess formed in the underside of the housing.

An integral finger Hi which extends inwardly from one of the walls of the uppermost spacing shell or block 3 engages the head I04 of the bolt.

iii)

Electrical control and wiring The side wall 4 of the burner housing is formed to receive a junction box I06 to which is mounted the control mechanism (not shown). Electrical leads or wires II I and I I2. from the motor 22 are contained in an insulated conduit .Ili! which runs through an opening in the rear wall of the housing and through an internal chamber of the housing, the leads being brought into the junction box and connected to terminals I98 and I09. Leads or wires H4 and H5 from the transformer I00 are also contained in an insula'ted conductor or conductors which extend through an internal chamber in the burner housing and are brought into the junction box and connected one to the terminal we and the other to terminal H9.

The relay of the safety combustion control mechanism for governing the burner operation is contained in a metal box which fits over the junction box I06. Electrical connection is made with the various terminals in the latter .by captive screws or other means not shown. Besides the motor and transformer, other devices may be connected into the control mechanism through the junction box Hit, the leads or wires from these devices being attached to terminals in the junction box that are contacted by the captive screws of the relay box. The control system desirably employs a conventional photoelectric or phototube cell H8 to monitor the operation of the burner. The photocell is mounted in the air tube 86, .in a container I25 which faces toward the open mouth of the burner head 99. The container is supported on a bracket [2B which is slidable .to different positions along the rigid fuel conduit 89.

A flexible electric conductor JIRI is connected to the photocell H8 through the rear of the container I25 and extends into the junction box 106 where it is connected to terminal I22. The 'phototube cathode is grounded to the burner housing structure. A set screw I23 is provided in the photocell bracket 12!! to retain the latter in adjusted position on the rigid oil conduit. Reference is made to my copending application Serial No. 149,550, filed l llarch 14, 1 950, which claims certain of the features disclosed herein.

In accordance with the patent statutes the principles of the present invention may be utilized in various ways, numerous modifications and alterations being contemplated, substitution of parts and changes in construction being resorted .to as desired, it being understood that the embodiment shown in the drawings and described above is given merely for purposes of explanation and illustration without intending to limit the scope of the claims to the specific details disclosed.

What I claim and desire to secure by United States Letters Patent is:

1; In a pressure atomizing oil burner of the type having a power unit comprising an electric motor and a fan and a fuel pump secured to and driven by the motor, the improvement which comprises a cantilever type bracket for supporting the power unit, said bracket being secured to the housing structure of the burner and extend ing laterally therefrom, said bracket also having a concave underside to receive the electric motor, and means resiliently suspending the motor from spaced portions of the bracket wh reby the underside of the motor is substantially unobstructed, the suspending means including elements secured to and located on opposite sides of the motor,

said elements being disposed wholly below the level of the top of the motor and separately secured to spaced portions of the bracket, the motor and the bracket being generally spaced from and making connection with one another solely through said suspending means.

2. In an oil burner of the pressure atomizing type, a housing structure defining a fan chamber, a bracket member secured to the housing structure and extending laterally therefrom in cantilever fashion, said bracket being curved across its width and having a concave underside, an electric motor disposed in the concavity of the underside of the bracket, means suspending the motor from the bracket, the suspending means including elements secured to and located on opposite sides of the motor, said elements being disposed wholly below the level of the top of the motor and separably secured to spaced portions of the bracket, the motor and the bracket being generally spaced from and making connection with one another solely through said suspending means, a fan disposed in the fan chamber and connected to the electric motor to be supported and driven thereby, and a fuel pump for supplying liquid fuel to the burner connected to the motor to be supported and driven thereby.

3. In an oil burner having a housing and m electric motor, in combination, a bracket secured to and supported by the housing, the bracket including a cantilever portion extending horizontally from the housing and having a concave underside received embracingly about the top of the motor, and resilient elements tensioned between spaced points on opposite sides of the cantilever portion of the bracket and the motor to suspend the motor from the bracket in generally spaced relation, the tensioned resilient elements constituting the sole supporting connection between the bracket and the motor.

4. In an oil burner having a housing and an electric motor, in combination, a bracket secured to and supported by the housing, the bracket including a cantilever portion extending horizontally from the housing and having a concave underside received embracingly about the top of the motor, flange means extending horizontally from the opposite sides of the bracket cantilever portion, and resilient elements connected between the horizontal flange means of the bracket and the motor to suspend the motor from the bracket in generally spaced relation, the resilient elements constituting the sole supporting connection between the bracket and the motor.

5. In an oil burner having a housing and an electric motor, in combination, a bracket secured to and supported by the housing, the bracket including a cantilever portion extending horizontally from the housing and having a concave underside received embracingly about the top of the motor, flange means extending horizontally from the opposite sides of the bracket cantilever portion, means on the motor providing horizontally extending ears, and resilient elements connected between the horizontal flange means of the bracket and the horizontal ears on the motor to suspend the latter from the bracket in generally spaced relation.

6. In an oil burner having a housing and an electric motor, in combination, a bracket secured to and supported by the housing, the bracket including a cantilever portion extending horizontally from the housing and having a concave underside received embracingly about the top of the motor, the opposite sides of the cantilever portion being formed with integral, generally horizontal flanges disposed on opposite sides of the motor intermediate the top and bottom of the latter, and means connected between the horizontal flanges of the bracket and the motor to suspend the motor from the bracket in generally spaced relation.

7. In an oil burner having a housing and an electric motor, in combination, a bracket secured to and supported by the housing, the bracket including a cantilever portion extending horizontally from the housing and having a concave underside received embracingly about the top of the motor, the opposite sides of the cantilever portion being formed with integral, generally horizontal flanges disposed on opposite sides of the motor intermediate the top and bottom of the latter, and resilient elements tensioned between the bracket flanges and the motor to suspend the motor from the bracket in generally spaced relation, the resilient elements constituting the sole supporting connection between the bracket and the motor.

8. In an oil burner having a housing and an electric motor, in combination, a bracket secured to and supported by the housing, the bracket including a cantilever portion extending horizontally from the housing and having a concave underside received embracingly about the top of the motor, a bell extension removably mounted on one end of the motor, a pair of connecting elements extending between spaced points on opposite sides of the cantilever portion and the motor, and another pair of connecting elements extending between other spaced points on opposite sides of the cantilever portion and the bell extension to suspend the motor and the bell e tension from the bracket in generally spaced relation.

9. In an oil burner having a housing and an electric motor, in combination, a bracket secured to and supported by the housing, the bracket having a generally horizontally extending cantilever part that includes a portion overlying and substantially conforming to the shape of the top surface of the motor, a pair of connecting elements extending between spaced points on opposite sides of the cantilever part and the motor to suspend the motor from the bracket in generally spaced relation, the cantilever part of the bracket also including substantially horizontal flanges extending beyond the end of the conforming portion of the bracket, a bell extension removably mounted on one end of the motor, and another pair of connecting elements extending between the extended bracket flanges and the bell extension to suspend the latter from the bracket.

10. In combination, a power unit and a support therefor, the unit including a motor having a rotatable shaft and journal means for the latter, a bell extension removably mounted on one end of the motor, a device carri d solely by the bell extension and including a rotatable shaft, a coupling connecting the shafts for driving of the device shaft by the motor shaft, the support including a housing and a contilever bracket on the housing, said bracket having a generally horizontally extending, part that overlies and. substantially conforms to the top of the motor, a pair of connecting elements extending between spaced points on opposite sides of the horizontal part of the bracket and the motor to suspend the latter beneath the cantilever bracket in spaced relation, and another pair of connecting elements extending between other spaced points 9 on opposite sides of the horizontal part of the bracket and the bell extension to suspend the latter from the bracket.

11. In combination, a power unit and a support therefor, the unit including a motor having a rotatable shaft and journal means for the latter, a bell extension removably mounted on one end of the motor, a device carried solely by the bell extension and including a rotatable shaft, a coupling connecting the shafts for driving of the device shaft by the motor shaft, the support including a housing and a cantilever bracket on the housing, said bracket having a generally horizontally extending part that overlies and substantially conforms to the top of the motor, the overlying part of the bracket being discontinuous across said end of the motor and the bracket having extension portions disposed on opposite sides of the motor and extending beyond said motor end and alongside the bell extension, and spaced pairs of connecting elements suspending the unit from the bracket in generally spaced relation to the latter, one pair of said connecting elements extending between the bracket and the motor and another pair of said connecting elements extending between the extension portions of the bracket and the bell extension.

12. In combination, a power unit and a support therefor, the unit including a motor having a rotatable shaft and journal means for the latter, a bell extension removably mounted on one end of the motor, a device carried solely by the bell extension and including a rotatable shaft, a coupling connecting the shafts for driving of the device shaft by the motor shaft, th support including a bracket having generally horizontal components extending along opposite sides of the motor and of the bell extension, and spaced pairs of resilient connectors mounting the unit on the support, one pair of said connectors extending between the horizontal components of the bracket and the motor and another pair of said connectors extending between such components and the bell extension, the resilient connectors constituting the sole supporting connection between the unit and the support.

13. In combination in an oil burner, a housing through which combustion supporting air is conducted, an electric motor having a rotatable shaft, said motor also having opposite ends L through which the motor shaft projects, an air fan secured on one end of the motor shaft and disposed within the housing, a supplemental support member disposed over the other end of the motor shaft, said supplemental support member being secured on the motor for facile removal and replacement and being formed with an opening of substantially uniform section substantially aligned with the motor shaft, an oil feeding pump formed with a plug portion, said plug portion of the pump being disposed Within the opening in the supplemental support member and the pump being substantially wholly supported by said supplemental support member, said pump having a shaft extending through the plug portion and projecting into the interior of the supplemental support member, coupling means connecting the said other end of the motor shaft to the projecting pump shaft, and means on the housing having connection with the motor to support the motor, fan, supplemental support member and pump as a unit.

14. In combination in an oil burner, a housing through which combustion supporting air is conducted, an electric motor having a rotatable shaft, said motor also having opposite ends through which the motor shaft projects, an air fan secured on one end of the motor shaft and disposed within the housing, a supplemental support member disposed over the other end of the motor shaft, said supplemental support member being secured on the motor for facile removal and replacement and being formed with on opening of substantially uniform section substantially aligned with the motor shaft, an oil feeding pump formed with a plug portion, said plug portion of the pump being disposed within the opening in the supplemental support member and the pump being substantially wholly supported by said supplemental support member, said pump having a shaft extending through the plug portion and projecting into the interior of the supplemental support member, coupling mean connecting the said other end of the motor shaft to the projecting pump shaft, a bracket secured to the housing and extending outwardly from the housing cantilever fashion and. means connecting the motor to the cantilever bracket to support the motor, fan, supplemental support member and pump as a unit substantially wholly by said cantilever bracket.

15. In combination in an oil burner, a housing through which combustion supporting air is conducted, an electric motor having a rotatable shaft, said motor also having oppositeends through which the motor shaft projects, an air fan secured on one end of the motor shaft and disposed within the housing, a supplemental support member disposed over the other end of the motor shaft, said supplemental support member being secured on the motor for facile removal and replacement and being formed with an opening of substantially uniform section substantially aligned with the motor shaft, an oil feeding pump formed with a plug portion, said plug portion of the pump being disposed within the opening in the supplemental support member and the pump being substantially Wholly supported by said supplemental support member, said pump having a shaft extending through the plug portion and projecting into the interior of the supplemental support member, coupling means connecting the said other end of the motor shaft to the projecting pump shaft, a bracket secured to the housing and extending substantially horizontally outwardly therefrom in cantilever fashion, and means elastic resiliently suspending the motor from and generally below the cantilever bracket yieldingly to suspend the motor, fan, supplemental support member and pump as a unit substantially wholly from said cantilever bracket.

REGINALD W. BECKETT.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,991,194 Child Feb. 12, 1935 2,209,477 Reibel July 20, 1940 2,253,597 Wyne Aug. 26, 1941 2,281,144 Dillon Apr. 28, 1942 2,287,462 Beckett June 23, 1942 2,309,683 Wahlmark Feb. 2, 1943 2,405,196 Elliot et al. Aug. 6, 1946 FOREIGN PATENTS Number Country Date 153,733 Germany Feb. 15, 1938.