US2629391A - Automatic self-cleaning dishwashing machine of the recirculating type - Google Patents

Description

Feb. 24, 1953 H UMM EL. AUTOMATIC SELF-CLEANING DISHWASHING MACHINE 0F THE RECIRCULATING TYPE 4 Sheets-Sheet l Filed May l, 1948 r w /w n I "fao Feb. 24, 1953 Y F s, HUMMEL 2,629,39

. AUTOMATIC SELF-CLEANING DISHWSHING MACHINE OF THE RECIRCULATING TYPE Filed May l, 1948 4 Sheets-Sheet 2 Feb. 24, 1953 F. s. HUMMEL AUTOMATIC SELF-CLEANING DTSHWASHTNG MACHINE oT THE RECIRCULATTNG TYPE 4 Sheets-.'Slleei'l 3 Filed May l, 1948 Feb. 24, 1953 F. s. HUMMEL AUTOMATIC SELF-CLEANING DISHWASHING MACHINE OF' THE RECIRCULATING TYPE Filed May 1, 1948 4 Sheets-Sheet 4 ...VH I. """E Patented Feb. 24, 1953 AUTOMATIC SELF-CLEANING DISHWASH- ING MACHINE OF THE RECIRCULATING TYPE Frederick S. Hummel, Toronto, Ontario, Canada, assignor to Triumph Dishwashers Limited, Toronto, Ontario, Canada Application May 1, 1948, Serial No. 24,478

' 7 Claims. (Cl. 134-110) This invention relates to dishwashing machines `and the principal object of the'invention is to provide a simplified completely automatic and extremely emcient dishwashing machine Which will ensure that all of the dishes, glasses, silverware or other articles placed therein will be thoroughly cleaned, rinsed and dried, and

ywhen removed will be completely free from adhering food or other soil particles and from water marks, leaving the dishes in a clean sparkling I condition.

A further important object is to provide an attractive and compact dishwashing machine which will be extremely convenient to use and will complete the washing and drying of the dishes in a minimum of time.

A still further and important object is to provide an economical machine which will require a minimum of water to eiect the thorough cleansing of the dishes to eliminate any heavy drain on the hot water supply.

A still further important object is to provide a dishwashing machine which will utilize a constant volume of water sufficient to effect the thorough cleaning and rinsing of the dishes independent of the variations in the water supply pressure.

A still further object is to provide a machine which will be self-cleaning.

The principal feature of the invention consists in arranging an impeller assembly adjacent the bottom of a washing chamber to circulate and distribute a heavy flow of washing -or rinsing liquid uniformly throughout the-chamber, supbe washed with their surfaces fully exposed to thewashing and scouring action of the circulating liquid, providing a novel screen arrangement to collect and remove food particles and food soil from the circulating liquid. A further object is to provide control means to effect at defined intervals the entrance lof a predetermined constant volume of liquid into the chamber prior to the Washing and the rinsing of the dishes, and to evacuate the liquid and any collected particles subsequent to the washing and rinsing operations.

A still further important feature consists in providing a spray arrangement to assist in the ushing of the collected particles out of the chamber during the evacuation of the washing liquid.

Referring to the accompanying drawings,

Figure 1 is a part elevational view of the machine with the front panel partly broken away.

Figure 2 is a plan view of the machine with the closure lid broken away and the dish-holding rack removed. .i

Figure 3 is a vertical mid-sectional view on th line 3 3 of Figure 2 showing the impeller and distributor and the position of the dishes and glasses with their surfaces exposed to the scouring effect of the circulating liquid.

Figure 4 is an enlarged sectional view on the line 4 4 of Figure 2 illustrating the particlecollecting sump and screen separator.

Figure 5 is a sectional View on the line 5-5 of Figure 4.

Figure 6 is a plan detail of the drain valve operating mechanism.

Figure 7 is a side elevational View of the control motor showing operating cams and switch mechanism operated thereby.

Figure 8 is an elevational view of the drain valve operating cam andillustrating diagrammatically the manner in which it operates the drain valve during the machine cycle.

Figure 9 is a view similar to Figure 8 but showing the cam controlling the operation of the water inlet control valve.

Figure l0 is an elevational view of the cam controlling the duration of the machine cycle.

Figure l1 is a diagrammatic illustration of the timing relationship of the various phases of the machine cycle and illustrating diagrammatically a complete machine cycle as provided by the cams illustrated in Figures 8, 9 and 10.

Referring to the drawings, the dishwashing chamber or compartment is in the form of,a square shape tub l supported within acasing 2, one or more of the panels of which may beremovable to provide access to the control mechanism of the machine.

The bottom of the tub I slopes toward the centre to form a central depression 3 towards which liquid circulated into the tub will flow.v

Supported centrally beneath the bottom of the tub by brackets 4 is an operating electrical motor 5 provided with a shaft extension 6 extending through the bottom of the tub and connected by the resilient sleeve 'I to the motor drive shaft 8.

The impeller assembly 9, preferably of the type disclosed in co-pending United States patent application No. 572,653 filed January 13, 1945, and which issued October 30, 1951, as United States Patent No. 2,572,983, includes a sleeve Il) surrounding the shaft extension 6 and projecting through the bottom of the tub and provided with radially extending wings or vanes Il arranged adjacent the tub bottom.

The internal bearings I2 permit the shaft extension 6 to rotate freely within the sleeve I0 and suitable gaskets I3 provide a water-tight seal at the bottom of the tub.

Secured to the shaft extension 6 is a somewhat conical-shaped sleeve I4 which surrounds the sleeve I5 and extends down to the wings II. v Rigidly secured to the lower end of the sleeve I4 are a plurality of impeller blades I5 which extend radially outwardly above the vanes ll. These impeller blades are preferably inclined obliquely to force the liquid upward.

Surrounding the sleeve I4 is the impeller housing I6 formed with a rolled lower edge I1 supported in suitable notches I8 on the vanes II of the stationary sleeve I0.

Secured within the housingIB are a pluralityv of substantially vertical curved vanes I6 which serve to straighten out the liquid thrown up by the impeller blades I5 into an axial upwardly V`flowing stream.

Mounted on the shaft extension 5 above the top of the impeller housing I6 is a distributor I9 of the type disclosed in co-pending application No. 24,531 i'lled May l, 1948.

As shown in Figure 4, the under deecting surface 2U of the distributor is twisted spirally to form a continually changing deflecting angle frombelow horizontal or negative angle at the portions 2l to the vertical deecting portion as at 22.

During the operation vof the impeller the rotating impeller blades I5 act to force any liquid lying in the central depression 3 out the opening 23 in the top of theimpeller housing as a solid round cross sectionstream of water. This stream vstrikes the Vdistributor I9 and is directed by the distributor in an outward direction at any angle from the horizontal to the vertical corresponding to the angle of the distributor deilecting surface 2| on which the upwardly moving stream im- Dnges,

Thus the portion of the upwardly moving stream striking the distributor deflecting surfaces at .2I will be deiiected outwardly and somewhat downwardly, while the portion of the stream flowing past the vertical deflecting portion 22 of the distributor will flow directly upwardly and a spiral distribution of the water stream will be obtained.

Since the distributor I9 is iixed to the shaft extension 5 it rotates with the shaft and the vol- `urne swept out by the deflected water stream will correspond to the volume of revolution of the spiral and will therefore includel all parts of the'tubl.

With the deflecting surface of the distributor a` true spiral even coverage of the tub will be obtained 'while if certain sections of the tub are found to require more or a stronger flow of 24 which extends from adjacent the centre of the bottom to one corner tapering in depth and width towards the corner.

Around the periphery of the sump 24 is a depressed shoulder 25, as shown particularly in Figure 5, and supported on this shoulder is a relatively ne-mesh screen 26, the frame 21 of which carries an encircling rubber gasket 23 which forms a seal with the shoulder 25.

The screen 25`is thus flush with the bottom or" the tub and extends from the inner end of the sump 24 to adjacent the outer end of the sump but terminates short of the outer sump end to leave an unscreened opening 29 leading into the sump.

Arranged at the bottom of the sump 24 is a drain outletV 35 which is closed by the drain valve 3I'formed with ua central extension 32 having a groove 33 in which the forked end of the lever arm 34 pivoted in the wall of the drain engages.

Secured to the outer end of the lever arm 34 is a transverse bar 35 which is operated through the vertical rod 36 to rock the lever arm 34 to open and close the drain valve.

Arranged above the sump 24 and .extending through one side of the tub is a water inlet 31 in the form of a spray nozzle which is directed to spray the incoming water over the upper surface of the screen 26.

Opening into the tub adjacent the bottom and immediately above the central depression 3 is an air vent 38 which leads upwardly from the 'tub bottom but terminates below the water inlet 31 so that any overflow of liquid in the tub will escape through the vent and cannot flow .back through the inlet in the event of a negative or abnormally low pressure in the inlet pipe.

A second air vent 39 leads from the tub adjacent the top and communicates with the exhaust 40 which `is in the form of a grill opening through the front of the casing extension 4I at the back of the machine.

The inner wall of the tub I adjacent the top is formed with a bevelled shoulder 42 extending around its perimeter and secured to the top of the casing 2 adjacent the back of the machine by suitable hinges 43 is a closure lid 44 provided with `a gasket 45 on its undersurface to engage the shoulder 42 and seal-the top of the tub.

The front end of the closure lid 44 is provided with a notch 45 to receive the operating finger 4'I of a suitable press type latch 48 arranged within the casing, and exposed through the casing opening 49. The latch functions to normally hold the lid in closed position but is readily operated by the plunger 50 extending through the casing opening 49 to release the lid.

Also incorporated in the latch structure 48 is a suitable safety switch 5I which is arranged to close when the lid is closed but opens upon opening of the lid to de-energize the control mechanism hereinafter described to prevent spraying Vof the liquid out of the tub and to prevent the operator from becoming scalded.

As illustrated in Figure 3, the large dishes and platters and the like 52 are supported edgewise adjacent the bottom of the tub by the lower rack assembly 53, while the glasses 54 and cups or goblets 55 are supported with their interiors directed towards the centre 0f the tub by the Upper rack assembly 56. The silverware 51 is adapted to be supported in ya basket 58 suspended from the upper rack assembly 56.

,The upper rack 56 is supported in the grooves 66 of the studs 61 extending from the walls 'of thetub. i

As in the case of the lower rack the upper rack 'is formed of aplurality of inter-connectedperipheral bars 68, 89 and 10 which conform to the general contour of the interior of the tub.

Connected in the supply pipe 13, which feeds from a hot water tank 14 located within the casing beneath the tub I and with the water inlet 31, is a solenoid-operated control valve 15 of the type disclosed fully in my co-pending U. S. application Serial No. 24,479, filed May 1, 1948, which is actuated through the solenoid 16 to open and close the supply pipe 13 and when open to retain a constant output or outlet pressure whereby a constant volume of Water from the tank is discharged into the tub in a given time.

Arranged beneath the tub I is a suitable electrically operated slow-speed controlmotor mechanisrn 11 which revolves the shaft 18 very slowly to form the timing control of the machine operation.

Fixed to the shaft 18 are a plurality of cams 19, 89 and 8| which are shown in elevation in Figures 8, 9 and 10 respectively. The cam 19 is the drain valve operating cam. Figure 8, which engages a roller 82 on the outer end of a lever arm 83, the inner end of which engages the vertical rod 36 connected with the drain valve operating bar in a loose connection, as shown in Figure 3.

The drain operating cam is provided with two spaced eccentricities 84 and 85 to effect the opening of the drain valve twice during the rotation switch 81 which is connected to operate Ithe 9 solenoid 19 of the inlet control valve 15.

The cam 8| functions to stop the machine after its cycle upon completion of the revolution of the shaft 18 and is provided with a single eccentricity 88 which is adapted to engage a push-push type of switch 89.

A press button switch 90 arranged within the casing adjacent the top of the machine and having its operating plunger projected through the casing opening 9| is arranged to short out the contacts of the switch 89 when same are opened by the cam 8|.

The switches 89 and 98 control the electrical power to the machine and when both are opened power is cut off but when either one or the other is closed the electrical power is delivered to the machine.

The silverware basket 5B may be either wire frame or perforated, the basket having a central opening 92 therethrough. At the top of the opening 92 is a deflect-or element 93 in the form of a somewhat conical shell to deflect water or liquid at the top of the basket directly on to the ends of the silverware which are preferably arranged as shown in Figure 3 with their handles downwardly. The deiiector element also permits water to .strike the tub lid 44 and cascade downwardly on to the silverware and the dishes and glasses below.

To facilitate the opening and closing of the tub the cover or closure 44 is counterbalanced by springs 94 which are secured at their lower ends to the casing and at their upper ends to extensions 95 of the lid.

The cycle of the machine as controlled by the motor control mechanism 11 and corresponding to one revolution of the shaft 18 is clearly illustrated in the diagrammatic showing of Figure l1 with figures 8, 9 and 10 showing the relative 6 position of the cams at the instant of starting the machine.

When it is desired to operate the machine the dishes, glasses and silverware are placed in the proper brackets and basket and the lid 44 is swung closed, closing the safety switch 5I to apply power to the switch 89 and push-.button switch 98. Since the switch 98 is held open by its operating cam 8l and since the switch 89 is normally open, no power will be fed to the operating components of the machine.

To initiate the cycle the push-button switch 99 is operated by-passing switch 89 and applying power to the slow-speed control motor mechanism 11 and simultaneously applying power to the impeller motor 8. I

'I'he initial movement of the shaft 18 by th control mechanism 11 allows the drain valve to close and following the closing of the drain valve the cam 88 operates to close the micro switch 91 to energize the solenoid 18 of the control valve 15 to direct water at a constant pressure into the inlet 31 from the water tank 14 which may be thermostatically controlled to provide water of the desired temperature, preferably about 175 so that on the completion of the fill of the tub the immediate temperature losses will reduce the temperature to approximately 140 for washing so that egg or other food particles will not be cooked on to the surface of the dishes.

The inlet 31 directs the water as a spray over the surface of the screen 26 and fiows towards the central depression 3 in the bottom of the tub from where it is circulated by the impeller assembly with a suitable detergent placed in the tub to provide an effective washing liquid.

With the valve mechanism used a constant volume of water is discharged through the inlet into the tub during the interval the solenoidoperating switch 81 is actuated by the cam projection independent of the pressure variation in the supply tank 14.

The quantity of water required is actually quite small and need only be sufcient to cover the bottom of the tub to a depth less than the top of the air vent 38.

The impeller blades I5 force the Washing liquid as an axial stream up through the opening in the top of the impeller housing iB as previously described and the distributor directs the stream to all parts of the tub to eiect the washing of the dishes and other articles, the large highspeed liquid globules effecting a rapid and thorough dish-soil removal.

This washing action continues for a definite period of time corresponding to the time interval between the eccentricities 88 and 85 on the drain opening cam 19.

Previously in dishwashing machines the washing operation has been ineffective to the extent that large food particles are continuously recirculated through the washing chamber, adhering to the dishes and when the washing water is drained these food particles remain on the dishes, spoiling the eiect of the wash. This major disadvantage has been completely overcome in the present machine by the provision of the sump 8 and screen 29 without requiring a large, complicated high-capacity iilter system.

As the water is circulated and thrown outwardly by the distributor and since the washing compartment or tub is of a square or rectangular design there is a strong flow of water down the corners. A denite portion of this flow will be to the corner at which the sump 24 terminates 7 and this water or washing liquid enters the un covered opening 29 leading into the sumpA and Vilows inwardly to return to the impeller.

Since the screen is of a relatively nne mesh sufficient to lter out all of the larger particles, these will be trapped in the sump and will be prevented from recirculating with the liquid as it returns to the impeller.

.trapped under the screen iilter.

The larger particles gathering on the underside of the screen serve as a barrier to the smaller -food particles,- most of which are also trapped inthe sump. Since the smaller particles are readily removed in the rinse their complete filtering is not required. In practice it is found that in approximately two vto three minutes all of the larger food particles and the majority of thesmaller Aones are removed from the washing Vliquid.`

At the completion of the wash the drain valve is operated by the cam le to open, allowing the washing liquid to ilow out the drain 3d. The

-outflowing wash water or liquid carries the food particles trapped in the sump down the drain. Any particles which may cling to the underside of this screen are washed oi by the action of the water level receding as it drains away and by the falling of the Water on top of the screen from the distributor during the wash,

To ensure however that the screen is perfectly clean the Water inlet control valve 'l5 is operated to allow the water from the tank 'i4 to discharge through the water inlet 3l. This incoming water sprays over the top surface of the screen to dislodge any remaining particles prior to the nal closing of the drain valve by the cam 19. Thus an additional ushing of the screen occurs just before the drain valve closes so that any dislodged particles will be carried down the drain and will be prevented from recirculating throughout the chamber during the rinsing operation.

At a short interval after the control valve 15 has-been operated through the cam 30 to open position the drain valve closes and the tub begins to ll With hot water. As the water reaches an I appreciable depth the impeller assembly which is continuously rotating begins to force the water throughout the tub. At a short interval after the closing of the drain valve sufficient water for the rinsing has been supplied to the tub and the Water inlet supply is cut ofi by the action of the cam 80 ie-.energizing the solenoid controlling switch 81. The clean water is then recirculated throughout the washing chamber or tub for a short interval to completely rinse the dishes. At the conclusion of the rinse the drain valve is operated by the cam eccentricity 85 of the cam 19 to allow the rinse water to drain away. The drain valve is held open for a considerable length of time due to the shape of the cam as shown in Figure 8, and during this period the impeller continues to rotate and draws air in through the air vent 38 at the bottom of the tub and forces same through the dishes and out the air vent 39 at the top of the tub.

After a short interval the cam 8l operates to open the switch 8g to interrupt powel` to the impeller motor and to the control motor mechanism to stopl the machine. It will be noted that as the machinestops the drain valve is still openwhile the inlet valve vis closed.

Following the completion of the machine cycle the closure lid or cover 44 may be left closed and the dishes will continue to dry in their own heat by the strong ilow of air through the chamber or tub as caused by the natural chimney effect provided by the vents 38 and 39. 4 This chimney effect therefore does not necessitate the continual fanning by the motor until the dishes are d ry, saving in operating power and the lid can remain. closed and serve as a table surface with the steam escaping through the exhaust 40,

With the screen 26 arra nge d above thehsump 24 functioning in themannendesribed tor-emo@ ,food particles, .these particles will be prevented,

immediately above the drain the screen, willv also be cleaned by thereceding water andufurthercby the Spray directed over its surface. .Howevenuif at intervals it is found desirable to clean the screen it may be readilylifted oi the shoulder 25 and removed.

It will be understood that while the impeller and distributor arrangement provides a very strong flow of water throughout all parts o f the tub or dishwashing compartment, only a small quantity of water need be allowed to enter the tub to provide this desirable iloW as the water is continually recirculated by the impeller which operates continually from start to stop of the machine cycle, eifecting the wash, rinse and fan-dry.

What I claim as my invention is:

L In anautomatic dishwashing machine, a dishwashing chamber, a closure vfor said chamber, an impeller arranged centrally adjacent the "bottom of said chamber to circulate a heavy; flo'w theimpeller from beneath said impeller at least to adjacent the wall lof said chamber, a'screen substantiallyflush with said surrounding bottom wall overlying said sump and extending below said impeller and dening, an unscreened opening leading' into said sump adjacent the wall of said chamber to permit unimpeded entrance into said sump beneath said screen'of particles carried by a portion of the circulating liquid returning to said impeller through said 'opening'a'portion of said circulating liquid cascading on said screen to flush particles introduced beneath said screen from clogging said screen, a water inlet above said sump to direct water through' said screen inv a direction opposite the direction of circulating liquid carrying particles through said opening and returning to said impeller, a drain at the bottom of said sump, a valve closing said drain, means for effecting the introduction lof liquid into said chamber through said inlet, means for operating said valve to evacuate the chamber, and control means for controlling the operation of said liquid-introducing means-and said valve-operating means.

2. In a dishwashing machine, a substantially rectangular dishwashing chamber having a bottom sloping inwardly towards the centre, a closure for said chamber, an impeller assembly arranged centrally adjacent the bottom of said chamber to circulate a heavy flow of liquid throughout said chamber to be returned to said impeller by the slope of said bottom, support means to hold dishes or other articles to be washed with their surfaces exposed to the scouring action of the circulating liquid, said bottom being formed with a sump extending from adjacent the centre to adjacent one corner thereof and sloping inwardly toward the centre thereof to return liquid to the centre of said chamber beneath said impeller assembly, a screen over lying said sump, an unscreened opening into said sump adjacent said chamber corner, a portion of the circulating liquid directed by the walls of said compartment to said corner entering said sump through said opening and carrying food particles removed from said dishes into said sump to be collected on the underside of said screen upon recirculation of the liquid moving upwardly to said impeller through said screen from the sump and a portion of the circulating liquid cascadinU on said screen ushing particles collected on the underside of said screen from clogging said screen, a Water inlet above said sump, a drain at the bottom of said sump, a valve closing said drain, means for effecting the introduction of liquid into said chamber through said inlet, and means for operating -said valve to evacuate the chamber.

3. A device as claimed in claim 2 in which said screen is flush with the bottom of said chamber and is removable.

4. A device as claimed in claim 2 in which said water inlet comprises a spray nozzle adapted to direct water over the surface of said screen to dislodge any particles adhering to the underside thereof.

5. In a dishwashing machine, a dishwashing chamber, an impeller mounted centrally in said chamber adjacent the bottom and continuously circulating a body of cleansing liquid in said chamber and self-cleaning means progressively removing food soil particles from said continuously circulating cleansing liquid comprising, a sump formation formed in the bottom of said chamber at one side of said impeller, said sump being set in a surrounding bottom wall and extending generally radially of the impeller from beneath said impeller to adjacent the wall of said chamber, a screen inset in said bottom and overlying said sump formation, said screen extending below said impeller clear of the path of liquid thrown up by said impeller and tree of projection above said surrounding wall and defining an unscreened opening to said sump removed from the centre of said chamber to permit a portion of circulating liquid to enter said sump beneath said screen to carry food particles therebeneath while permitting the remainder of the cleansing liquid to cascade on said chamber bottom and screen in circulation to flush said screen from above while permitting substantially free circulation of said liquid, and a drain leading from said sump.

6. A dishwashing machine, comprising a dishwashing chamber, an impeller in said chamber' for continuously circulating a body of cleansing liquid in said chamber, a sump formed in the bottom of said chamber below said impeller at one side of said impeller, said sump being set in a surrounding bottom wall and extending generally radially of the impeller from beneath said impeller to adjacent the wall of said chamber, a drain leading from said sump, a valve closing said drain, and a screen substantially ush with said surrounding wall covering a major portion of said sump and extending below said impeller clear of the path of liquid thrown up by said impeller and defining an unscreened opening to said sump spaced from the centre of said chamber to direct a portion of a circulating body of cleansing liquid beneath said screen in returning to said impeller without impedance to soil particles carried thereby to trap particles beneath said screen While leaving the remainder of said circulating body of liquid unimpeded in return to said impeller with a portion of said remainder cascading on said screen from above to flush particles trapped therebeneath from screen clogging position.

7. In a dishwashing machine, a dishwashing chamber, an impeller mounted centrally in said chamber adjacent the bottom for continuously circulating a body of cleansing liquid in said chamber, the bottom of said chamber sloping inwardly towards the centre and having a sump therein at one side of said impeller, said sump being set in a surrounding bottom wall and extending generally radially of the impeller from beneath said impeller to adjacent the wall of said chamber, said sump sloping from a point which is located at a level above the central portion of said bottom towards said central portion, a screen substantially iiush with said surrounding wall overlying said sump and inclined substantially at the slope of said bottom and dening an unscreened opening to said sump remote from the central portion of said bottom to conduct a portion of circulating liquid each circulation to said impeller from beneath said screen up through said screen, a portion of the remainder of the circulating liquid cascading on said screen from above to flush said screen in a direction opposite the direction of flow therethrough of liquid conducted from beneath said screen to said impeller, and a water inlet arranged above the sump, a drain leading from -said sump and control means controlling said impeller means and liquid flow into and out of said chamber through said inlet and outlet respectively.

FREDERICK S. HUMNIEL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,262,042 Heermans Apr. 9, 1918 1,445,320 Johnson Feb. 13, 1923 1,597,361 Hazard et al Aug. 24, 1926 1,681,322 Cave Aug. 21, 1928 1,893,797 Foster Jan. 10, 1933 1,899,019 Deutsch Feb. 28, 1933 1,915,079 Watt June 20, 1933 1,927,665 Kirby Sept. 19, 1933 1,995,332 Snyder et al Mar. 26, 1935 2,155,271 Jones Apr. 18, 1939 2,254,269 Clark et al Sept. 2, 1941 2,287,628 McMahan June 23, 1942 2,314,332 Ferris Mar. 23, 1943 2,443,091 Zademach June 8, 1948 2,468,584 Wotring Apr. 26, 1949

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