Патент USA US2530204

Nov. 14, 1950
F. B. HARVUOT
2,530,198
FILTERING APPARATUS
6 Sheets-Sheet 1
Filed July 51}; 1944
7
34
INVENTOR.
Fem/v 5 A/Aevuar
“W Mam
Nov. 14, 1950
2,530,198
F. B. HARVUOT
FILTERING APPARATUS
Filed July 31, 1944
23
6 Sheets-Sheet 2
25
42
39
35
38
lag/w
Nov. 14, 1950
2,530,198
F. B. HARVUOT
FILTERING APPARATUS
Filed July 31, 1944
6 Sheets-Sheet 3
I07
THERMOSTHT/C SWITCH
?eA/vx 5. Aéwvuar
INVENTOR.
WW
Nov. 14, 1950
F. B. HARVUOT
2,530,198
FILTERING APPARATUS
Filed July 31, 1944
6 Sheets-Sheet 6
:7l.i/.I.V‘/
Hawk 5’. Mew/or
Patented Nov. 14, ‘1950
2,530,198
UNITED STATES PATENTw OFFICE
2,530,198
FILTERING APPARATUS
Frank B. Harvuot, Fort Wayne, Ind., assignor to
Bowscr, Inc., Fort Wayne, Ind., a corporation
of Indiana
Application July 31, 1944, Serial No. 547,446
8 Claims. (Cl. 210--179)
1
2
This invention relates to an apparatus for ?l
These and other objects will become apparent
tering oils such as Diesel crankcase lube oils.
from a study of this speci?cation and the draw
More specifically, it relates to ?ltering appara
ings which are attached hereto, form a part
tus having a plurality of independent ?lter ele
hereof, and in which:
ments which may at will be removed individually 5
Figure l is a rear elevation of the ?lter with
from the How path of the incoming liquid so that
the outer casing removed to show the ?lter cas
the length of the overall ?ltering cycle will be
increased.
'
In prior ?ltration'practice, the brevity of the
?ltration cycle resulting from the clogging of
the ?lter element has proved extremely aggra
vating and inconvenient. The resultant inter
ruption of operation has been costly. The pres
ent invention provides a simple solution to over
come this inherent difficulty.
One object of the invention is to provide a ?l
ing, the pump, fan, and piping.
Figure 2 is a side elevation of the unit viewed
from the right of Figure l, but with the housing
10 removed.
Figure 3 is a top view of the apparatus with the
housing removed, showing the hand wheel,
heater, flow indicator, and other parts.
Figure 4 is a schematic wiring diagram of the
electrical system employed in the apparatus.
Figure 5 is a sectional view of the ejector mech
tering apparatus in which the ?ltration cycle
anism and the cover plate.
will be substantially lengthened.
Figure 6 is similar to Figure 2, but taken par
tially. in section to show the internal structure
_
‘
Another object of the invention is to provide
?ltering apparatus wherein a high rate of- ?l 20 of the unit.
‘
tration is maintained.
Figure '7 is a cut-away view showing the in
Yet another object of the invention is to pro
ternal structure of the heating unit.
vide a plurality of ?ltering elements in a cas
Figure 8 is a cut-away view of the ?ow sight in
ing, and means for forcing ?uid to be ?ltered
dicator showing the pointer and the arrange
through only a predetermined member of such 25 ment of the electrical components.
elements.
Figure 9 is a view of the ?ow sight of Figure
A further object of the invention is to provide
8‘showing the arrangement of the liquid actuated
?ltering apparatus wherein ?lter elements may
elements.
be individually removed at will from the ?ow
Figure 10 is a diagrammatic view of the liquid
path to present a new initial ?ltering surface.
~
30 circuit.
It is another object of the invention to pro
Referring now to Figures 1, 2, 3, and 6, the ex
vide ?ltering apparatus wherein adequate tem
ternal casing or housing I of the apparatus is
perature and pressure control of the liquid are
suitably supported on the frame, which is gen
maintained.
erally designated by the numeral 3. Disposed in
Yet another object 'of the invention is to pro
substantially the upper half of the structure and
vide ?ltering apparatus, wherein substantially
supported by cross-supports 5 of the frame 3 is
edge-type ?ltration is utilized.
the body of the ?lter, generally designated as ‘I.
It is a still further object of the invention to
The body ‘I of the ?lter comprises an upper cy
provide ?ltering apparatus wherein improper op
lindrical portion 9 which forms the actual ?l
eration is immediately indicated.
>
Another object of the invention is to provide
a ?lter element formed of absorptive paper wound
into a roll, which'both ?lters and dehydrates the
40 tration chamber and the sump II, which latter
portion is partially cylindrical but extends lat
erally in one direction as shown in Fig. 3.
The
bottom l0 of this lateral portion slopes toward
a rectangular cleanout opening [2, the periph
oil.
Yet a further object of the invention is to 45 ery of which is ?anged as at I3. The cylinder
provide a plurality of such ?lter elements or rolls
opens directly into the sump and the opening is
in series in a magazine with separators there
substantially unrestricted. The ?anges l3 have
between to facilitate separation.
.
threaded holes adapted to receive screws [5
Another object of the invention is to provide
which serve to hold the gasket I4 of the cover
a ?lter element of absorptive paper ribbon 50 plate I‘! in ?uid tight engagement with the
wound into a relatively ?at roll of large diam
?anged portion l3. A drain plug I9 is disposed
eter relative to its thickness so that it resem
in the bottom of the sump ll. 1
v
v
bles a disc rather than a roll.
The ?ltration chamber 9 is open at its upper
A further object of the invention is to provide
?ltering apparatus which may be quickly and
easily dismantled and reassembled.
end and has an outwardly extending ?ange 2|.
This ?ange 2| has threaded holes which receive
‘screws 23 which pass through the cover plate 25.
3
2,580,198
The screws hold the gasket 23 of the cover plate
in sealing relation against the end of the cham
ber 9.
As shown in section in Figure 5, the cover plate
25 has a central bore 29 to accommodate ‘a rod
21 to whosev lower end is suitably fastened a
pressure plate 29. The lower end of the bore
'is constructed to receive a packing 3| and a
packing gland 33, to effectively seal the chamber
from the atmosphere. The upper end of the bore
is counterbored and threaded ,to receive a slotted
tube 35 which loosely surrounds the rod 21. A
threaded hole 35 is disposed angularly in the
cover plate 25 to receive a screw 31 which en
gages the tube 35 and prohibits its rotation in
the cover plate. The tube 35 is externally
threaded throughout its whole length to receive
a hand wheel 34 which is adapted to bear upon
the top side of pins 39 which are ?xed in and
transversely of the rod 21 and extend through
the diametrically opposed, longitudinal slots 40
in the tube 35 and project out under the hub of
the hand wheel for operation thereby. A nut
42 also threadedly engages the tube 35 and bears
against the bottom side of the pins, so as to hold
the rod 21 in the position to which it is adjusted
by the hand wheel 34. It will be obvious that
turning the hand wheel 34 in one direction will
exert downward force on the pins 39, rod 21,
plate 29 and the ?lter elements (described be
low) which will be engaged by the pressure plate
29. Nut 42 may be used to raise the rod 21 after
the handwheel has been backed away from the
pins. The cross-sectional view ‘of a rib of the
' cover plate is indicated by the numeral 4|. Suit
4
cooler the ?ltered liquid passes to the point of
use or storage through a ?tting 34' which is a
part of the ?ltered liquid line to the discharge
line 54.
A manually operated shut-off valve 35 is dis
posed in a second pipe 33 (Figs. '1 and 3) con
necting the street L 53', which enters the sump,
with the street L 55' which enters the channel
65 of the manifold 55. The manifold is thus con
nected with the sump ll so that the ?ltrate re
maining in the cylinder above the manifold when
operation is stopped may be drained into the
sump either through port 31 and channel 93 or
through ports 53 and manifold 55. Also, when
15 operation is stopped, the channel 95, which
places the upper portion of the ?lter chamber
in communication with the manifold through
ports 51 and 58, allows equalization of pressure
therebetween during operation and relieves the
20 pressure when the valve 95 is opened as described
above. The application of outlet pressure to
the upper portion of the chamber assists in hold
ing the ?lter elements down against the pump
pressure. Itis, of course, necessary to relieve
25 this pressure when the plate 25 is to be removed
to permit the insertion of additional ?lter ele
ments.
,
The tank of a thermostatically controlled heat
ing unit, generally designated by the numeral 39,
'30 and shown in detail in Fig. 7, is supported on the
cylindrical portion of the sump H and is pro
vided with a suitable outlet line 91 (See Figs.
3 and '7) connecting it to the sump. A T 1|’
and a pipe ‘H connect the inlet of the heating'
35 unit 59 with the outlet side of a pump 13 (see
ably disposed in the cover plate is a manual air
Figs. 1 and 2). Another pipe 75 (Figs. 2 and 3)
release valve 33.
connects the sump ll directly to the T 15' con
Referring now speci?cally to Figure 6, the in
nected to the inlet side of the pump 13 through
ternal structure of the ?ltration chamber and
an automatic pressure relief valve 80, and thus
the ?lter elements will be described. The pres 40 provides a by-pass line for un?ltered liquid,
sure plate 29 previously described is adapted to
which by-passes the filter.‘ A pressure gage 13
engage compressibly the uppermost of a plural
and a dial-type thermometer 9| are suitably con
ity of ?lter elements 43 which are disposed one
nected to the sump. The numeral 14 (Fig. ‘1)
on top of another except for the intervening
designates the main inlet line to the pump 13
spacers 41. The lowermost element is supported
which has disposed therein a check valve 19 and
by suitable springs 5i fastened to the wall of
is connected by T 15' to the suction side of the
the sump and extending partially across the cy
pump. A line 19 is provided with a valve 11
lindrical portion. The springs support, to a
which is connected to the T 1|’ and thus connects
very limited degree, the filter elements, against
the outlet side of the pump 13 to the inlet line
the action of the pressure plate 29 in compressed 50 14 upstream of the check valve to provide a pump
by-pass.
relation therewith, but any large pressure ex
erted by the pressure plate will overcome the
The fan 83 is driven ‘directly by a motor 85
spring supports and therefore elect the lower
which also drives the pump 13 by means of a
most ?lter element into the sump ii.
belt 81. The pump 13 and motor 85 are suita
The filter elements comprise a compressed cel 55 bly bolted to the lower part of the frame 3.
lulose rope core 45 and the main body 45 which
Referring specifically to Figure 7, the heating
consists of a roll of tightly and spirally wound
unit 69 comprises a casing 89 of cylindrical cross
cellulose paper (260 wraps per diametral inch).
section. To the upper periphery of the casing
The single wrap or layer is comparable in com
89 is screwed a cover 9| from which depend the
position, thickness, and quality to the commer
cial product known as “Kleenexl’ Spacer plates
41, preferably a single disc. of 4 mesh screen,
are placed between each pair of ?lter elements.
Elongated holes 53 are formed circumferen
tially around the sidewall of the chamber 9 in a
position above the lowermost ?lter element 43.
Referring to Figures 1, 2 and 6, an outlet man
ifold 55 surrounds the exterior of the chamber
"Calrod” or other electric heating coils 93 con
trolled by a switch I01. The terminals 94 of the
coils are disposed without the cover 9! but within
a cap 95 which is suitably fastened to the cover.
The coils 93 when suspended within the casing
89, encompass the outlet pipe 91 which from its
opening 99 adjacent to the cover 9|‘, extends
downwardly through the bottom of the casing
89 and thence to the sump H. The inlet pipe ‘H
9 and has a channel 55 which spans the small
from the pump opens into the casing 89 near the
holes 53 in the sidewall thereof.
70 bottom thereof thus necessitating complete liquid
A ?ow indicator 59 (Figs. 2, 3 and 6) to be de
contact with the coils before passage into the
scribed later, is disposed in a pipe 51, 51' (Fig.
outlet. Similarly disposed within the casing 89
2 and 3) which connects the manifold 55 to a
and encompassed by the heating coils 93 and a
heat exchanger or cooler 3!, which is supported
cap I02 and tube I 94, is the thermostatic liquid
in the lower part of the frame 3. From the
?lled bulb or element NH and its tube H16 in con
9,580,198
duit I04, which controls switch I01 to energize or
deenergize the heating coils in accordance with
the temperature of the oil in the casing.
The element I M being in the casing 89 is at '
substantially the same temperature as the oil
therein. The bulb IOI is connected to any con
6
snugly in the bore. The pressure plate 29 is then
inserted in the cylinder 9 after having been posi
tioned adjacent the cover plate 25 and the cover
plate 25 is bolted in sealing position. The hand
wheel 34 is then turned to force the pressure plate
29 against the uppermost of the ?lter elements 43
ventional liquid operated switch by the tube I06
thus compressing them against the springs 5I,
so that expansion or contraction of the liquid
will open and close the switch respectively.
Referring now to Figures 1, 3, 4 and 7, it will be
and the apparatus will be ready for operation.
seen that a manual switch I03 connects both the
After connecting the inlet 14 to a source of
10 dirty oil and the outlet 64 to a receiver, the
manual switch I03 is closed to energize the heat
motor 85 and the heater 69, in parallel, to a 220
volt A. C. line I05. A switch I01, controlled by
ing unit 69, green light III, and the motor 85.
The dirty oil will be drawn through inlet 14 and
the thermostatic element IOI, is provided for
check valve 16 and pumped through conduit 1I
the heating unit 69, while control means I09
into the heater 69 and thence by way of conduit
serve to automatically shut off the motor when
91 into the sump II. Filtration will not proceed
a predetermined amount of overloading is en
at the desired rate until the desired oil tempera
countered. This latter is preferably a common
ture and consequently the proper viscosity is
“Thermatron” resistance control element as
reached, for at a lower temperature resistance to
manufactured by the Allen-Bradley Corporation.
?ow through the ?lter elements 43 will create
A green light “I is connected in series with the 20 enough pressure to open the pressure relief
manual switch I03 to signal when the unit is
operating. A red lamp H3 in series with and
controlled by a normally open switch H5, is
actuated by ?ow indicator 59.
valve 80 which is preferably set at 75 p. s. i. The
oil is thus recirculated through the by-pass valve
80, line 15, pump 13, the pump discharge line H, '
the heater 69, the conduit 91 and sump II, until
~ A ?ow indicator and switch operator similar
the required ?ltration temperature is attained.
to that shown in my Patent No. 2,388,843, issued
The thermostatic switch I01 opens and closes to
November 13, 1945, for Slow Feed Indicator may
control the heater as required to maintain the
be connected in the ?ltrate outlet line 51-51',
?ltering temperature whereat the oil viscosity is
as is clearly shown in Figures 2, 3 and 6. The
su?‘iciently reduced to enable it to pass through
so
inlet H1 is, of course, connected to pipe 51 while
the filter elements 43.
the outlet I45 is connected to the pipe 51'.
The oil actually passes through only the ‘lower
As shown in Figs. 8 and 9, liquid ?ows into
most unit 43 and a portion of the unit directly
the indicator inlet I I1 and into a tube I23 having
above, and thence outwardly through the holes 53 '
a small hole “9 and a large hole I4I. Part of
into the manifold 55 where it is collected. The
the liquid may leak through the constantly open
greater portion of the impurities are retained on‘
hole II9, but not in su?icient quantities to re
the surface of the ?rst element 43. The impuri
lieve pressure on a piston I2I disposed in the bore
ties passing the surface are retained in the ?rst
of the tube I23. The piston under pressure of
element and the surface of the second element.
the incoming liquid thus moves away from a pin
Substantially edge-type ?ltration is achieved, but
I25 which passes diametrically across the tube 40 the liquid must also pass radially through at
and serves as a stop, and against the action of
least part of the element to reach the outlet.
spring I21, which engages a pin I29 set 'in a bail
The oil passes from the manifold through con
I3I which is pivotally mounted, and moves pin
duit 51, ?ow indicator 59, line 51’, into the cooler
_ I29 and bail I3I in a clockwise direction. This
BI, and out the discharge line 64 to storage.
movement is transmitted by a link I33 to arm I35
When a sizeable decrease in ?ow rate occurs
and shaft I31, thence to a cam I39 and an in
due to clogging of the foremost element 43, as
dicator I4I mounted on and rotated by shaft
will be disclosed by the flow indicator 59, the
I31. As the piston moves to the left, the indi
valve 11 in line 10 is opened, whereby the dirty
cator and switch closing cam reach a position at
oil is merely recirculated through the pump 13
which a micro-switch lever I53, which rides on
and the pressure in the sump II is therefore
the cam, is released by the cam, whereupon the
relieved. The valve 65 in line 63 is opened to
normally open (self-opening) switch I I5 (see
allow drainage of oil from above the elements
Fig. 4) is permitted to open. The liquid ?ows
in the ?ltration chamber into the sump through
from the bore of tube I23 through one or more
the continually open channel 66 and permits
holes I4 I, which may be of any desirable size, into
equalization of pressure on opposite sides of the
body I43 and out through tube I45. Holes I41
?ltering elements. The hand wheel 34 is turned
in tube I45 are provided as outlets from the body far enough to cause the pressure plate 29 to
into tube I45 when piston I2I is adjacent the
eject the foremost element 43 and its spacer 41
inlet end of tube I45. If ?ow is substantially
into the sump II, thereby presenting a new
stopped, the piston I2I is in its right-hand posi 60 ?lter
element and consequently a clean ?lter
tion, and the cam I39‘will hold the switch lever
surface. It is thus apparent that the ?ltering
I 53 down, to thus hold the switch closed to ener
operation is substantially uninterrupted.
gize the red lamp II3 to light, serving to indicate
Complete cessation of ?ow through the ?lter
the cessation of ?ow to the operator.
65 1 relieves pressure on piston I2I and spring I21
and actuates shaft I31 of the ?ow indicator 59
Operation
to close the switch II5 which energizes the red‘
In preparing to operate the ?lter, the cover
light II3 to warn the operator of the condition.
25 is removed, whereupon several ?lter units 43
If, for any reason, the motor 85 is subjected to
with their accompanying spacers 41 are placed 70 a predetermined overload, (preferably 60% in
in the ?ltration chamber 9 so as to rest on the
the apparatus shown), the thermatron resist
springs 5I'. The number of elements inserted
ance control unit 93 stops the motor before any
in the ?lter may vary from a minimum of one to
difficulty results to interrupt operation.
the capacity of the chamber 9 which depends
The ?ltrate is cooled by passage through the
upon the length thereof. The elements ?t rather 75 cooler 6| and emerges therefrom through con
2,530,100
duit ll at approximately room temperature.
The fan continually forces air through the cooler
ti. when the run is completed or the elements
43 are all ejected except one, operation is
stopped by opening the main switch I03. The
air release valve ll in the cover plate 25 is
opened, the manual valve 85 controlling flow
from the manifold 85 to the sump Ii is opened,
and the drain plug it is removed, thus allowing
the liquid to drain out of the cylinder, manifold,
channel and sump. -The cover plate l'l may
then be removed and the ejected ?lter elements
43 taken out. The operation may then be re
head to receive said rod, longitudinal slots in
said screw, a pin mounted transversely in said
rod and extending through said slots, and a
hand wheel mounted on said screw and adapted
to engage said pin for actuating said rod.
5. In a ?ltering apparatus, a ?ltration cham
ber having one end open, an inlet compartment
of greater cross-sectional area than the ?ltra
tion chamber connected thereto, a plurality of
independent, separable ?lter elements disposed
in end to end contact with each other and slid
able in said chamber, means disposed at the junc
ture of said chamber and compartment for hold
ing said elements in said chamber, said holding
?lter elements in place as described above.
15 means being adapted to resistabiy yield toward
It is obvious-that various changes may be
said compartment in response to movement of
made in the form, structure and arrangement
said ?lter elements toward said compartment,
of parts without departing from the\spirit of
an outlet in said chamber disposed intermediate
the invention. Accordingly applicant does not
the ends thereof and spaced from said holding
desire to be limited to the speci?c embodiment 20 means by at least the thickness of a ?lter ele
disclosed herein primarily for purposes of illus
ment, means in the ?ltration chamber operable
tration, but instead he desires protection falling
at will and disposed so as to urge said ?lter ele
fairly within the scope of the appended claims.
ments toward said holding means and serving to
What I claim to be new and desire to protect
overcome said holding means to eject the lower
by Letters Patent of the United States is:
most element into said compartment.
peated.
This, of course, requires putting new
i. In a ?ltering apparatuaa source of liquid,
6. In a ?ltering apparatus, a ?ltration cham
a pump having a suction port in communication
ber having an open end communicating with an
with said liquid source and an outlet port, a
enlarged inlet compartment, an outlet in the side
?ltration chamber having an enlarged inlet por
of the ?ltration chamber, a plurality of separable,
tion connected to the outlet port of said pump, 30 independent ?lter elements slidably mounted in
an outlet in said chamber, a plurality of ?lter
said ?ltration chamber, said inlet chamber and
elements releasably supported in said ?ltration
outlet being so spaced as to have at least one
chamber, manual means for ejecting said ele
of said elements disposed therebetween, means
ments, one by one, into said inlet portion, a by
adjacent the open end of the ?ltration chamber
pass line connecting theinlet portion of said 35 for supporting said ?lter elements in said ?ltra
chamber with the suction port of said pump,
tion chamber, said supporting means being con
and a manually operable valve in said line
structed and arranged to resistingly yield to the
whereby liquid pressure in said chamber may
movement of said elements toward said compart
be relieved while said ejecting means is oper
ment, and means disposed'ln the other end of
ative.
40 said ?ltration chamber and operable at will to
2. In a filtering apparatus, a ?ltration cham
force said elements toward said open end to
ber having one end open and communicating
overcome said supporting means whereby to eject
with an enlarged inlet tank and an outlet in the
said elements, one by one, into said compartment,
wall of said ?ltration chamber, a plurality of
' saidenlarged compartment having a lateral, nor
separate and independent ?lter elements
.mally closed opening to permit removal of the
stacked, one on the other, and mounted for slid- ‘
ejected elements therefrom.
ing in said ?ltration chamber, means adjacent
'1. In a ?ltering apparatus, a ?ltration chamber
the open end of said ?ltration chamber for re
and magazine having a closed end and an open
leasably supporting said ?lter elements in said
end serving as an inlet, an outlet spaced from
chamber, means comprising a pressure plate
said open end, said outlet comprising a plurality
mounted in the other end of said chamber and 50 of radial holes disposed in the sidewall of said
adapted to engage the ?lter element remote from
?ltration chamber and enclosed by a circum
said open end so as to eject the element adjacent
ferential manifold, a plurality of disc-like ?lter
the open end into the enlarged inlet tank, and
elements disposed in and transversely of said
manual means for actuating said plate.
chamber, in face to face contact with each other,
3. In a ?ltering apparatus, a ?ltration cham 55 said inlet and outlet being spaced so that at least
ber having one end open and communicating
one element may be disposed between them, ele
with an enlarged inlet tank and an outlet in the
ment displacing means mounted at the closed
end of said chamber and comprising means for
wall of said chamber, a plurality of ?lter ele
engaging the nearest element and means for mov
ments stacked, one on the other, in said ?ltra
tion chamber, means adjacent the open end of 60 ing said engaging means and element toward
said chamber for releasably supporting the ?lter‘
said inlet, the motion of said element being
transmitted to the other elements by reason of
element adjacent the open end of said chamber,
means comprising a pressure plate in the other
said face to face contact to eject the element,
end of said chamber adapted to engage the ?lter
adjacent the inlet, out of said chamber.
8. In a ?ltering apparatus, an open-ended
element adjacent said other end so as to eject 65
the lowermost element into the enlarged inlet
?ltration chamber, a plurality of separate and
tank, manual means for actuating said plate,
independent ?lter elements slidably mounted in
and means for locking said plate in position.
said chamber, each element being in the form
of a disc disposed transversely of the chamber
4. In a ?ltering apparatus a ?ltration cham
ber, a plurality of ?lter elements movably 70 and having face contact with the elements on
either side of it, an inlet and an outlet in said
mounted in said chamber, a head for closing said
chamber so spaced as to have at least one of
chamber, means for ejecting the elements from
said chamber comprising an actuating plate, a
said ?lter elements disposed therebetween, means
rod attached thereto and slidable through a seal
for urging said elements toward the open end of
in said head, a hollow screw mounted on said 76 said. chamber, and means comprising a plurality
9,980,198
~10
Number
of leaf springs fastened to the lower periphery oi
1,642,864
said chamber wall at said open end, said springs
1,743,122
having free ends extending beneath the edge
1,906,553
of the element nearest them whereby pressure
applied to the element by said urging means will 5 1,870,885
2,065,658
overcome pressure of the‘ springs and cause the
element to be moved past the springs.
FRANK B. HARVUOT.
REFERENCES CITED
10
tile oi'this patent:
UNITED STATES PATENTS
Number
Name
Date
- 174,795
Fogarty et a1. _~._-__ Mar. 14. 1876
1,387,325
Probat ......... -_I.- Feb. 1. 19:1
16
,
Date
. Williams _________ -- Sept. 20, 1927
'Egg'ert __________ __.Jan. 14, 1930
Babitch -___ ...... -_ May 19, 193i
.-Alaop ____>_,______ -_ Aug.>9.v1932
Compton -,____, ____ __ Dec. 29. 1936
2,068,395
2,103,572
Burck'halter' et a1. ..- Jan. 19, 1937
Burckhalter et a1; -- Jan. 19, 1937
\wells ____________ _-"Dec. 28, 1937
2,110,009
Weidenbacker ---.._ Mar. 1. 1939
2,178,930
2,286,432
2,389,803
Crawford ________ __ Nov. 7. 1939
Monsarrat ....... _- June 16. 1942
2,068,394 ‘
The following references are of record in the
Name
I
Number
9,953
Dollinger ___---__- Nov; 27, 1945
FORmGN'PATENTS
Country
Date
Great Britain. ......... __ of 1898
»