US 2655023 A
Description (OCR text may contain errors)
Oct- 13, 1953 T. E, D. BILDE ET AL 2,555,023
APPARATUS FOR WASHING CLOTHES AND CENTRIFUGALLY EXTRACTING LIQUID THEREFROM Filed June 25, 1947 Patented Oei. 13, i953 APPABATUS FOB WASHING CLOTHES AND CENTBIFUGAILY EXTRACTING LIQUID THEBEFROM Tord Erik Daniel Bilde and Rolf Bertil Johannes Hultberg, Stockholm, Sweden, assigner: to Akticbolaget Elektrolux, Stockholm, Sweden,
a corporation of Sweden appiasuon June as, im, semi N. 'isasoo In Sweden February 23, 1945 lClniml. (CL 68-2) Our invention relates to clothes washing apparatus, and more particularly to such apparatus for washing clothes and other fabrics and the vlike and centrifugally extracting liquid therefrom.
An object of our inventionis to provide an improved washing and liquid-extracting apparatus of simplified construction which can be readily assembled. i
Another objectof our invention is to provide an improved apparatus of this kind in which the different parts are readily accessible, the washing and liquid extracting units being constructed in such manner that individual parts can be conveniently removed for cleaning and inspection while disturbing only a minimum number v015 other parts of the apparatus.
A further object of our invention is to provide an improved apparatus in which the/washing and liquid extracting portions are constructed as separate units independently'mounted alongside each other on a common base in such manner that maximum protection from washing liquid is afforded for the driving motor and mechanism operatively associating such motor and parts of the washing and liquid extracting units.
A still further object of our invention is to provide an improved apparatus of this kind in which the driving motor is housed within the liquid extracting unit and related to other parts in such manner that it is nicely protected and may be readily removed for inspection and cleangFurther objects and advantages of our invention will become apparent as the following description proceeds, and the features of novelty which characterize our invention will be pointed out with particularity in the claims annexed to and forming a part of this specication.
In the drawing, Fig. 1 is a vertical view taken at line I-I of Fig. 2, partly in section and partly in elevation, illustrating a combined washing and liquid extracting apparatus embodying the invention; and
Fig. 2 is a top plan view looking down on the apparatus shown in Fig. 1.
In the drawing, we have shown our invention embodied in a combined washing and liquid extracting apparatus comprising a base 9 upon which are separately mounted a washing unit III and a liquid extracting unit I I. A suitable source of heat, such as, for example, a gas burner I2, is associated with the washing unit III. A driving motor I4 for-'the apparatus ls located within the lower part ofthe liquid extracting unit I I.
Suitable mechanism is provided whereby the motor Il may be employed to drive a rotatably mounted perforated drum or basket Il within the liquid extracting unit I I for centrifugally extracting washing liquid from the clothes, and also for oscillating a washing element or agitator I8 within a washing receptacle I1 forming a part of the washing unit Ill. The mechanism operatively connecting the motor I4 to the drum l5 and to the washing element Il, as well as the motor itself, is protected from washing liquid collecting in the liquid extracting unit II and liquid which may be splashed when the apparatus is in use.
The various parts of the apparatus briefly referred to, and which will be described more fully hereinafter, are associated with one another in such a way that each part is readily accessible and can be conveniently removed for cleaning and making repairs while disturbing only a minimum number of other parts of the apparatus.
The washing unit Ill comprises the washing receptacle II of cylindrical form having a bottom I8 and an upstandirig side wall including a short bottom wall portion I9 of reduced diameter, and a higher extending main wall portion 20 of wider diameter. The upper end of the upstanding side wall is formed with an inwardly extending flange 2| shaped to receive and hold a cover (not shown) to prevent spilling of washing liquid. The agitator I6 is mounted in the receptacle II for oscillation therein about a horizontally extending axis and may be of a type like that described in application Serial No. 542,865 of T. E. D. Bilde, filed June 30, 1944, now Patent No. 2,491,081, granted December 13, 1949. It is to be understood, however, that the particular agitator or washing element referred to is merely illustrative and that other types of washing elements may be employed.
The agitator I6 is suitably journalled at one end in a bearing 22 fixed to the inside of the receptacle I'I, and at its opposite end may be removably connected in any well known manner to a driven member 23 extending through an opening 24 in the receptacle. The member 23 is associated with and forms a part of mechanism 25 mounted on the outside of the receptacle I1 which may be of any conventional type operable to oscillate the agitator I6 back and forth Within the receptacle.
The main wall portion 20 of the upstanding side wall at its lower part flares outwardly from l' the short wall portion I9 which essentially forms a neck of reduced diameter at the bottom of the receptacle. A perforated plate 26 is positioned in the receptacle I1 at the region from which the main wall portion 20 flares outwardly from the reduced neck portion I9. The perforated plate 26 serves as the actual bottom for the space in which the clothes to be washed are circulated and is formed with a downwardly extending flange 21 which snugly fits within the reduced neck portion I9 of the receptacle. While the clothes are held in the space above the plate 26, the washing liquid can circulate between the spaces above and below such plate through the apertures 28 therein.
The washing receptacle I1 is mounted on a stand comprising a housing 29 oi' cylindrical shape which may be formed of sheet metal. 'I'he upper end of the housing 28 receives the neck portion I9 of the receptacle. and these parts are tightly secured together by a. metal band or split ring 30 having ears or tabs 3|, only one of which is shown. adapted to be drawn toward each other by a tightening screw l2. The neck portion I9, the upper end of the housing 28, and the ring Il are formed with similar-shaped annular ridges so that these parts can be brought together with the ridges in nested relation. as shown in Fig. l. In addition, the upper edge portion of the housing 29 may be slotted at spaced apartoegions so that it will be sufilciently resilient to enable the ring 30 to draw the housing tightly about the reduced neck portion I of the washing receptacle I1.
Within the housing 29 is provided a horizontal partition 33 having a'central opening about the peripheral edge portion of which is fixed the lower end'of a tube or sleeve I4. The gas burner I2 is supported on the partition 33 by a number ot brackets I5, only one of which is shown, and so positioned that the burner llames project upwardly through the sleeve I4 to eti'ect heating of the bottom I8 of the washing receptacle I1. Gas is supplied to the burner I2 through a conduit which passes through an opening inthe housing 29 and is provided with a manually operable valve l1 and a nipple connection ll to whichag secured in an annular member II whose outer pewipheral edge portion is ilxed to the inside of the shell 42, as by welding or brazing, for example. Suitable packing 52 is preferably provided above the bearing Il to protect the latter from moisture.
The annular member II is formed with a V-shaped trough 53 in which liquid collects and from which the extracted liquid flows byv gravity into a lsuitable collecting vessel (not shown) through an inclined discharge spout 54 extending through an opening in the shell 42.
'I'he washing unit .I Il and liquid extracting unit II just described are separately mounted on the base l which is suitably formed of sheet metal and includes a top plate II and a vertical side wall 54 having an inwardly extending reinforcing ilange l1 at its lower end. Hence, the base l is completely open at the bottom at the region of the ange Il.
The top plate 55 is provided with two circular openings at the peripheral edges oi which are removably secured the lower ends of the housing 28 and shell 42, respectively. As shown, the lower ends of the housing 2l and shell 42 iit over collars or rings Il and ls, respectively, and rest and outwardly extending lower flanges 02 and ber '29 through an opening 4l in the housing 2l to which an exhaust nue 4I may be connected. The washing unit Il may also be arranged for electrical heating, if desired, in which case one or more electrical heating elements may be provided in the space between the bottom Il oi' the receptacle and the apertured plate 26.
The liquid extracting unit II comprises an outer shell or casing 42 of cylindrical form whose height is substantially the same as the overall height of the housing 2| and the washing receptacle I1 of the washing unit III. Within the upper part of the casing 42 is disposed the perforated drum Il which is adapted to be rotated for extracting washing liquid centriiugally from the clothes. The upper open end of the basket II receives a freely rotatable disc 43 journalled at 44 in a cover 45 which is hinged at 46 and adapted to be clamped in any suitable manner (not shown) in a closed position. When the cover 4I is locked in its closed position and the basket I i is being rotated, the disc 43 will also rotate and serves to guide the basket I5 at its upper end and prevent wobbling movement thereof when the basket is being driven at a relatively high speed.
An imperforate plate 41 is provided at a region within the drum Il which is spaced from the extreme lower imperiorate end thereof and de lines the bottom o1' the space for holding the clothes from which washing liquid is extracted. To the extreme lower end portion oi' the drum Il is ilxed a bottom end member 4l having a centrally disposed opening within which is rigidly connected the upper tapered end of a shaft 4l. ,Theshaitisarrangedinaballbearingll Il, the lower flanges being adapted to bear .against the underside or face of the top plate Il.
The collars Il and Il and the lower ends of the housing 2l and shell 42, respectively, are formed wi a number of aligned openings through whl'i pass threaded bolts adapted to receive tightening nuts Il. Strips of metal Il, which are curved orvarched in section, are disposedl about the lower ends of the housing and shell to hide the heads of the bolts C4 from view and provide a neat a ranceV at the base l.
The base l is p `vided with three or more legs `s1 which are nxestnereco in any mutable manner for supporting the apparatus in a slightly elevated position on a supporting surface Il. The legs I1 may be arranged to receive casters (not shown) to facilitate movement o! the apparatus, and ma Aalso be of a type which are adjustable to"ma e it possible to raise and lower the washing unit I Il and liquid extracting unit II when this is desired.l
It will now be Vseezrthat the two units Il and I I are separate and distinct and are independent oi' one another. Due to the manner in which the units I I and I I are removably secured to the base l, each unit may be removed'i'rom the base independently oi' the other. Moreover, since the units III and II are in spaced relation, a gap is provided between the umts which is completely open. This gap at the top of the units Il and II is bridged byasuita le table plate l! which desirably is relatively t ck in section and may extend from the washing receptacle I1 to the extreme outer or remote end oi' the' liquid extracting unit II, as shownrmost clearly in Fig. 2. The part of the table plate 68 extending beyond the gap between the units Il and II and overlying the shell 42 is formed with an opening through which access is had into the shell ,I2 and drum Il therein. The/,cover 4i for the liquid extracting unit may .be hinged at 4C to the. table plate Il.
The -table plate Il is formed with a downwardly extending sleeve portion ll which is received by the upper end of the casing 42. and also a leg 1I of such shape that it bears snugly against the outer surface of the washing receptacle I1. Tl., table plate 88 is removably secured in position in any suitable manner, as by countersunk caps screws (not shown), for example; and is formed with a slightly raised rim 12 and an inclined ramp 18 so that washing liquid that collects on the table plate during a washing operation, as during the transfer of clothes from the `washing receptacle to the drum I5, will flow by gravity into the washing receptacle.
The-compartment 14 provided in the bottom partnf the casing. 42 is advantageously employed VV'to house the electric motor I4 arranged to ro- -tate the drum I and actuate the washing element I8. As previously described, the annular member 5I and bearing 88, together with its associated packing 52, are of such construction that extracted liquid is prevented from passing into the compartment 14 and all of the liquid collecting at the top surface of annular member 5I flows through the discharge spout 54.
The motor I4 having shaft 15 is removably mounted at 18 to the inwardly extending fiangedz 8| of the collar or ring 58. Several mounts 18 may be provided which are distributed about the flange 8| and preferably resilient in character to dampen vibrations of the motor and minimize the transfer of such vibrations to the casing 42 and base 9 of the apparatus.
The shaft 15 of the motor I4 is in alignment with the shaft 49 rigidly fixed to the'lower end of the rotatable drum I5 and arranged to drive the latter ,through a friction clutch comprising cooperating elements 11 and 18. The lower element 11 is rigidly fixed to the upper end of the motor shaft 15, while the upper element 18 and a collar 19 fixed thereto are keyed on the shaft 49 and only axially movable thereon. The collar 19 and upper element 18 may be shifted up and down on the shaft 49 in any suitable manner. For example, the collar 19 may be arranged to receive the end of an operating member or lever 80 which may be operatively connected to a manually operable control conveniently located on the apparatus.
While the clutch just referred to may be of any suitable type, we have shown a friction clutch like that described `in application Serial No. 761,300, or R. B. J. Hultberg, filed July 16, 1947. In such a friction clutch the upper element 18 is in the form of a brush which, when it is moved downwardly, is adapted to engage the top face of the lower element 11. The frictional engagement of the ends of the brush bristles and the top face of the lower element are effective to transmit turning movement to the shaft 48 and drum I5 rigidly fixed thereto. With a friction clutch of this type, the motor I4 may be operated at its normal full speed and, due to the sliding frictional engagement of the brush bristles on the lower element 11 when the elements are brought together, the drum I5 will gradually increase in speed until it reaches the normal speed of the driving motor.
As previously mentioned, the motorI4 is also arranged to actuate the washing elementor agitator I6. The mechanism 28 mounted on the outsideof the washing receptacle I1 is of a type which is operable to impart an oscillatory movement to the agitator I 8. The mechanism 25 is vcompletely enclosed within a shell designed to close the opening 24 in the side wall of the recepwashing liquid splashing from the receptacle past the driven member 28 into the shell of the mech- A shaft 8| extends vertically downward from the mechanism 25 in the gap between the'washing unit I0 and liquid extracting unit II, and is journalled at its lower end within a sleeve member 82. at the underside ofthe top plate 55 of the base 9. In order to protect the shaft 8I from washing liquid, the latter is preferably housed in a hollow tube 88 connected at its upper end to the shell of the mechanism 25 and at its lower endto the top plate 55. The shaft 8I is adapted to be driven continually in one direction, and the mechanism 28 operatively connected thereto convertsrsuch continuous turning movement of the shaft 8I into an oscillatory movement of the driven member 28 for oscillating the agitator I8.
The motor I4 is operatively connected to the shaft 8| by mechanism including a grooved pulley 84 which is fixed to the lower end of the motor shaft 15,- and another grooved pulley 88 which is freely rotatable on the sleeve member 82. 'I'he pulley 85, which is driven by a belt 88 from the pulley 84, is provided with an integrally formed clutch element 81 which cooperates with another clutchelement 88 fixed to a collar 89. The clutch element 88 and collar 88 are keyed to the lower end of the vertical shaft 8I and only axially movable on the latter.
The collar 89 receives the end of a lever 98 which is pivoted at 9I and arranged to be moved up and down by an operating member 92. The member 82 may be connected by suitable control mechanism (not shown) to a conveniently located manually operable control at the vicinity of the control for connecting and disconnecting the drum I5 to and from the motor I4. When the lever 98 is moved upwardly by the operating member 92, the clutch element 88 engages the element 81, whereby the motor shaft 15 positively drives the shaft 8I through the belt 88 and clutch elements.
The manually operable control members for engaging and disengaging the friction clutch members 11 and 18 and clutch elements 88 and 89 may be operated so that the drum I5 and washing element I8 may be independently or simultaneously actuated by the motor I4. Such control members may be mounted on a suitable panel located beneath the table plate $8, and the mechanisms connecting such control members to the operating members and 82 may also be enclosed in one or more tubular members (not shown) which are like the hollow tube 83 and positioned adjacent thereto in the gap between the washing unit I0 and liquid extracting unit I I.
By housing the motor I4 in the lower compartment 14 within the casing 42, the motor is eeetively shielded and protected from liquid and also the heat developed by the burner I2 when heating of the washing liquid in the receptacle I1 is desired. A suitable opening having a sliding cover (not shown) may be provided in the housing 28 of the Washing unit I8 to facilitate igniting the gas issuing from the nozzles of the burner I2.
The relatively short distance between the base 8 and the supporting surface upon which the apparatus rests, together with the provision of the flange 51 at the bottom of the base 8 which serves as an apron or skirt, prevents liquid from splashing and coming in contact with the motor I4 and the exposed motion transmitting mechanism beneath the top plate 55 of the base. However, for
tacle, and suitable provision i8 made t0 prevent 'l5 additional protection a plate 88 may be remov- 7 ably secured, as by clips (not shown), for example, at the bottom of base 8 beneath the motor I 4 and the mechanism operatively connecting the motor and the vertical shaft 8I. As clearly seen in Fig. l, the space beneath the top plate 55 of base 8 by itself is of insuillcient height, when the base is being supported on the supporting surface 68, to house the transmission parts beneath the motor I 4 and the motor in its entirety in the vertical position illustrated. In the preferred embodiment shown, the spacebeneath the top plate 55 of base 9 by itself actually is of insumcient height to house the motor I4 in its entirety in the vertical position illustrated.
The central aperture in the collar or ring BI is of such size that, after the belt 88 is detached from the pulley 84 and the motor I4 is disconnected from the ring at 18, it can be freely withdrawn from the compartment 14 at the underside of the base 9. The friction clutch element 11 is withdrawn with and accompanies the motor while the other element 18 remains in position on the shaft 48. When the table plate 88 is removed after loosening its connections, the casing 42 can be readily removed from the top plate 55 without disturbing the washing unit I0. When control Aprovisions are provided immediately beneath the 68 to permit removal'of the casing 42 from the 30 accessible and may be interchanged with a similar o part while disturbing only a minimum number of other parts of the apparatus.
In addition to providing a simple and economical construction, theI different parts are so arranged in relation to one another that maximum protection from splashed liquid is obtained. In the preferred embodiment this relationship of parts involves providing the base 8 having a plate or member which is relatively near to a supporting surface upOn which the apparatus is adapted to rest, the base having a skirt or apron to provide a space at its underside -which is effectively shielded from liquid which may be splashed. The shell 42 of the liquid extracting unit II, whose upper end is substantially at the same level as the top of the washing receptacle I1, is of such height that the washing and liquid units III- and I I are at a convenient'working level.
The shell 42 extends below the bottom of the washing receptacle I1 while the driving motor I4 l5 of the latter. The mechanism for actuating the washing element I6 is independent of the mechanism provided for driving the drum I5 and includes one portion of the space at the underside of the top plate 55 of base 8, which is readily accessible vfrom the underside of the base 8, and another portion which extends upwardly in the gap between the units I0 and II from the base l to a height above the bottom o'f the receptacle I1.
The opening in the base 8 at the region of the shell 42 affords access into the motor compartment 14, the connections 18 for mounting the motor being readily accessible at such opening. By simply detaching the belt 88 from the motor pulley 84 and disconnecting the motor from its mounting, the latter can be readily withdrawn from the compartment 14, as previously explained. v
Although we have shown a single embodiment of our improved apparatus for washing clothes and centrifugally extracting liquid therefrom, we do not desire our invention to be limited to the particular arrangement set forth, and we intend in the claims to cover all modifications which do not depart from the spirit and scope of our invention g What is claimed is:
1. In washing apparatus of the class described having a washing unit including a washing receptacle and a washing element mounted for movement therein and a liquid extracting unit an csmg and. a drum mounted therein for rotation about a vertical axis to extract liquid centrifugally from clothes, the combination of a base, means. for mounting the washing unit and liquid extracting unit on said base alongside each other, said base having an opening affording access into the lower end of the casing, asingle electric motor mounted in the lower part ofthe casing beneath the drum. said motor being vertically disposed and having a driving element rotatable about a vertical axis substantially in alignment with the axis of rotation of the drum, means for supporting said base on a supporting surface, said supporting means providing a space beneath said base, means disposed entirely within the casing for transmitting motion from the upper end of said driving element to the drum to rotate the latter. transmission mechanism disposed entirely outside the casing for transmitting motion from the lower end of said driving element to the washing element, said mechanism including parts in the space beneath said base at the vicinity of the opening in the casing, the space beneath said base by itself being 0f insulcient height, when said base is being supported on the supporting surface, to house said ion parts and said motor in its entirety in said vertical position, and said base having provisions including a is disposed beneath the drum I5 and below the 00 downwardly depending skirt at the periphery bottom of the washing receptacle. The motor I4 is mounted at 18 so that a major portion thereof is housed within the compartment 14 with the shaft 15 extending vertically and in alignment with the drum I5.
The mechanism for transmitting motion from the upper end of shaft ls is disposed entirely thereof to protect said motor and last-mentioned parts from any liquid splashed at the vicinity o1' said base.
2. In washing apparatus of the class described having a washing unit including a washing reand extending downwardly from the top plate casing. a single electric motor having a driving shaft, means accessible at the opening for mounting said motor vertically with a major portion thereof positioned within the lower part of the casing beneath the drum and the lower end of the vertical driving shaft projecting downwardly beyond the lower end of the casing, said driving shaft being rotatable about a vertical axis substantially in alignment with the axis of rotation of the drum. means for supporting said base on a supporting surface. said supporting means providing a space beneath said base, means disposed entirely within the casing for transmitting motion from the upper end of said driving shaft to the drum to rotate the latter, transmission mech anism disposed entirely outside the casing for transmitting motion from the lower end of said driving shaft to the washing element, said mechanism including parts in the space beneath said base at the vicinity of the opening in the casing, the space beneath said base by itself being of insuicient height. when said base is being supported on the supporting surface, to house said transmission parts and said motor in its entirety in said vertical position,` and said base having provisions including a downwardly depending skirt at the periphery thereof 4to protect said motor and last-mentioned parts from any liquid splashed at the vicinity of said base.
3. Apparatus as set forth in claim 2 in which the parts of said transmission mechanism in the o space beneath said base include a pulley on said driving shaft and an endless belt cooperating therewith.
4. In washing apparatus of the class described havinga washing unit including a washing receptacle and a washing element mounted for movement therein and a liquid extracting unit including an upright casing and a drum mounted therein for rotation about a vertical axis to extract liquid centrifugally from clothes, the com` bination of a base, means for mounting the wash-- tect said motor and last-mentioned parts from any liquid splashed at the vicinity of said base, said first mechanism being so constructed and arranged that, after said endless belt is removed from said pulley and said mounting means is disconnected, said motor can then be freely withdrawn from the lower compartment.
5. In apparatus having a liquid extracting unit including an upright casing and a rotatable drum for centrifugally extracting liquid from clothes, such unit being mounted on a base, the combination of such a base having an opening affording access into the lower part of the casing, the casing having a partition intermediate the ends thereof to subdivide the latter into upper and lower compartments, means including said partition y for journaling the drum for rotation in the upper compartment about a vertical axis, said lastmentioned journaling means supporting the entire dead-Weight load of the drum and clothes therein from which liquid is adapted to be centrifugally extracted, an electric motor having a shaft, readily accessible mounting means on said casing adjacent sai-d opening for removably supporting said motor in the lower compartment to position the shaft vertically therein for rotation about a vertical axis substantially in alignment with the stub shaft of said drum, means for supporting said base on a supporting surface, said supporting means providing a space beneath said base, connecting means operable to connect said motor shaft and the drum, said connecting means including a clutch having cooperating elements associated with the drum and motor shaft, respectively, the space beneath said base by itself being of insufficient height, when said base is being supported on the supporting surface, to
ing unit and liquid extracting unit on said base alongside each other, said base having an opening affording access into the vlower end of the casing, a, partition intermediate the ends-of the casing to subdivide the latter into upper and lower compartments, means including the partition for mounting the drum in the upper compartment for rotation about a vertical axis, a single electric motor having a driving element, mounting means accessible at the opening for removably supporting said motor within the casing in the lower compartment thereof to position said driving element for rotation about a vertical axis substantially in alignment with the axis of rotation of the drum, means for supporting said base on a supporting surface, said supporting means providing a space beneath said base, first mechanism disposed entirely within the casing for transmitting motion from said driving element to the drum to rotate the latter, second mechanism disposed entirely outside the casing for transmitting motion from said driving element to the washing element, said second mechanism including parts in the space beneath vsaid base at the vicinity of the opening in the casing. such parts including a pulley on said driving element and an endless belt cooperating therewith, the space beneath said base by itself being of insumcient height, when said bas/vis being supported on, the supporting surface to house said transmission parts and said motor in its entirety in said vertical position, and said base having provisions including a downwardly depending skirt at the periphery thereof to prohouse said motor in its entirety in said vertical position, said elements being freely separable when said motor is Withdrawn from the lower compartment, and said element associated with said motor accompanying the latter upon its removal from said casing.
TORD ERIK DANIEL BILDE.
ROLF BERTIL JOHANNES HULTBERG.
References cited in the me or this patent UNITED STATES PATENTS Number Name Date 1,071,956' Psarski sept. 2, 1913 1,360,778 Neel Nov. 20, 1920 1,660,427 Ruiz Feb. 28, 1928 1,760,775 Peters May 27, 1930 1,766,213 Bock June 24, 1930 1,781,173 Green Nov. 11, 1930 1,787,243 Geldhof Dec. 30, 1930 1,842,030 Kirby Jan. 19, 1932 1,847,325 Allemang Mar. l, 1932 2,029,937 Nelson Feb. 4, 1936 2,112,584 Turner Mar. 29, 1938' 2,251,564 Conterman Aug. 5, 1941 2,268,204 Dunham Dec. 30, 1941 2,277,923 Morgenstern Mar. 31, 1942 21,291,088 Morgenstern July -28, 1942 2,334,858 Beattie Nov. 23, 1943 2,421,252 Dunham May 27, 1947 f 2,425,378 Lindemann Aug. 12, 1947 2,442,397 Candor June 1, 1948 FOREIGN PATENTS Number Country Date 263,303 Great Britain Dec. 30, 1926 291,087 ,Great Britain Oct. 1l, 1929 475,199 Great Britain Nov. 16, 1937 566,136 France Nov. 17, 1923