Double drum batch washing machine

A double drum batch washing machine comprises an inner cylinder, an outer cylinder, an inner helical transfer screw with the inner cylinder and an outer helical transfer screw within the space between the inner and outer cylinders. The inner helical transfer screw has a pitch in one direction and the outer helical transfer screw has a pitch in the other direction so that the compartments formed by the transfer screws within the inner cylinder and the space between the inner and outer cylinders define areas of overlap on the surface of the inner cylinder. The areas of overlap have holes formed therein so that fluid interchange is established between each outer compartment and only the corresponding overlapping inner compartment. Laundry is placed in the inner compartments and wash water is placed in the outer compartments such that it communicates with the inner compartments and the laundry contained therein. Laundry is washed by oscillating the washing machine through a predetermined angular arc. When the washing machine is rotated through a complete circle, laundry is transferred in one direction by the inner helical transfer screw and wash water is transferred in the opposite direction by the outer transfer screw.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to laundry washing machines and more 
particularly to industrial washing machines. 
2. Description of the Prior Art Industrial laundry washing machines having 
multiple washing compartments have been available for some time. Many of 
these machines comprise a horizontally mounted generally cylindrical 
chamber having a conveyor worm or auger screw rigidly mounted in the 
interior of the chamber so that several washing compartments are defined 
between the surfaces of the auger screw. Laundry to be washed in these 
machines is typically placed in the first compartment on one end of the 
machine and wash water containing proper detergents or other treating 
chemicals is introduced into the compartments. Introduction of wash water 
is typically achieved either by spraying it into the compartment from 
performations formed in the hub of the auger screw or by continuously 
supplying wash water from one end of the chamber and allowing it to flow 
through performations formed in the transfer screw walls and out the 
opposite end of the chamber. 
With laundry and wash water in the compartment, the machine will generally 
be oscillated through a predetermined angular range several times which 
agitates the laundry in the wash water. At the end of this oscillation 
period, the machine will be rotated through a 360.degree. arc which 
transfers the laundry to the next compartment in the chamber where it is 
again oscillated with wash or rinse water. This process is repeated until 
the laundry reaches the last compartment where it is removed from the 
machine. 
Washing machines of the type described above are known in the laundry 
industry as mono-shell or single drum machines, examples of which are 
illustrated and disclosed in U.S. Pat. Nos. of Stoll et al (4,210,004) and 
Schmidt et al (4,494,265). 
Another prior art washing machine design known as a double drum machine 
comprises several individual cylindrical inner washing drums connected 
together in series with passageways along their longitudinal axes. These 
inner drums are rotatable within fixed outer drums which contain wash 
water or other chemicals. Laundry to be washed is transferred to each 
inner drum in turn where wash water or other treating chemicals within the 
fixed outer drum enter through holes in the inner drum. The drum is then 
oscillated or rotated within the fixed outer drum to affect washing. At 
the end of each wash cycle, the laundry is transferred through the 
passageway to the next inner drum for the next wash cycle. This process is 
repeated for each washing drum until the laundry is clean. This type of 
machine is disclosed in U.S. Pat. Nos. to Pellerin et al (4,485,509), 
Harrsch (4,156,358), Hugenbrunch (4,109,493) and Bhaysar (Re. 30,214). 
The prior art washing machines exhibit several shortcomings in operation. 
In the continuous flow wash water machines, water intermixes between 
chambers so that batches of cloths of different colors cannot be washed in 
the machine at the same time. In addition, large volumes of water are 
required to maintain the flow of the wash water through the machine and 
complicated valve and pipe systems are required to introduce detergent and 
other treating liquids into the wash water flow. 
Machines with nonperforated auger screw walls in which wash water and other 
treatments are introduced into each chamber through a pipe extending along 
the axis of the screw also require complicated drain systems to remove the 
water from each compartment at the end of each wash cycle so that it will 
not be transferred with the cloths to the next washing compartment. In 
these as well as other prior art designs, dirt and heavy soil material 
washed from the laundry is often transferred with the laundry to the next 
compartment because it is too large to drain through the drain system with 
the water. 
Prior art machines comprising series of individual inner washing drums 
rotatable within fixed outer drums tend to be even more complicated than 
continuous flow machines. Because of the individual compartments, 
complicated means of delivering wash water to each drum and draining it 
therefrom at the end of a wash cycle is required. These machines use a 
large quantity of water and often have a plurality of valves and flow 
pipes to clog. 
SUMMARY OF THE INVENTION 
The present invention is an improved apparatus and method for treating 
industrial laundry that overcomes the disadvantages of prior art washing 
machines. It comprises an outer generally cylindrical chamber and a 
generally cylindrical inner chamber inside the outer chamber and spaced 
therefrom. The space between the inner and outer chambers contains a 
generally helical transfer screw or auger screw that divides the space 
into several compartments for containing wash water and transferring it 
from one end of the machine to the other upon rotation of the machine. The 
inner chamber also contains a generally helical transfer screw rigidly 
attached along its outer periphery to the inside of the inner chamber and 
dividing the inner chamber into several compartments for containing 
laundry and transferring laundry from one end of the machine to the other 
upon rotation of the machine. The inner transfer screw has a pitch angle 
that is substantially the same as the pitch angle of the outer screw but 
in the opposite direction so that as the washing machine is rotated, wash 
water or other treating material is transferred by the outer screw in one 
direction while the laundry or other textile to be treated is transferred 
in the other direction by the inner screw. 
The compartments formed in the space between the outer and inner chambers 
by the outer screw define areas of overlap on the periphery of the inner 
chamber with the compartments formed on the inside of the inner chamber. 
These areas of overlap on the inner chamber have perforations formed 
therein so that wash water in one of the outer compartments can flow only 
into the corresponding overlapping inner compartment and mix with the 
laundry therein. Thus the wash water does not intermix between wash 
compartments during washing. As the machine rotates during a transfer 
cycle, the wash water contained in only the last outer compartment is 
dumped out of the machine by the outside conveyor helix. Some water is 
also transferred out of the machine with the wet laundry. Only this amount 
of water expelled at one end by the outer helix plus the small amount that 
remains in the clothes need be added to the machine each cycle to maintain 
a full was water level. No complicated wash water inlet and drain system 
is required. Wash water is simply supplied to the first outside 
compartment on one end of the machine and it is conveyed to succeeding 
compartments by the outside helix upon each transfer rotation of the 
machine and finally out of the machine on the opposite end. In addition, 
dirt and other material from heavy soils in the laundry falls through the 
performations in the inner chamber to the corresponding outer chamber 
where it is transferred out of the machine with the wash water rather than 
being transferred with the laundry. 
Other objects, features and advantages of the present invention will become 
apparent upon reading the following specification, when taken in 
conjunction with the accompanying drawings.

DETAILED DESCRIPTION 
Referring now in more detail to the drawings, in which like numerals 
indicate like parts throughout the several views, FIG. 1 illustrates a 
typical prior art tunnel batch washing machine 25. It comprises an outer 
cylindrical chamber 26 which has rigidly mounted therein a transfer screw 
or auger or worm 27 which divides the interior of the chamber into a 
plurality of compartments 28, 28. The transfer screw has mounted along its 
longitudinal axis a wash water supply pipe 32 having perforations 29 
formed along its length within each of the compartments 28 formed by the 
transfer screw 27. The introduction of wash water into the compartments is 
controlled by a control valve system 33 and wash water is drained from 
each compartment after a wash cycle through drain valves 31. 
FIG. 2 is a cutaway perspective view of the present invention showing the 
double drum batch washing machine generally indicated by the numeral 10. 
The washing machine 10 has an outer generally cylindrical chamber 11 for 
containing wash water or other treating media. Outer chamber 11 is mounted 
for rotation about its longitudinal axis on roller means 34. Drive means 
is connected to the washer for oscillating it through a predetermined 
angular range to affect washing and rotating it through a complete circle 
to affect transfer of laundry and wash water, as will be explained 
hereinafter. Mounted inside the outer chamber and spaced therefrom is a 
generally cylindrical inner chamber 12 for containing laundry or linen to 
be washed or otherwise treated. In the space between the inner and outer 
chambers is rigidly mounted an outer transfer screw or auger or worm 13 
which has a pitch from left to right in the embodiment shown in FIG. 2. 
Outer transfer screw 13 divides the space between the chambers into a 
plurality of compartments 17, 17 for containing wash water during washing. 
Rigidly mounted around its periphery to the inside of inner chamber 12 is 
an inner transfer screw or auger or worm 14. Inner transfer screw 14 has a 
pitch that is generally the same in degree as that of outer transfer screw 
13 but in the opposite direction, running from right to left in the 
embodiment shown in FIG. 2. Inner transfer screw 14 divides the space 
defined by the inner chamber into a plurality of compartments 18 for 
containing laundry during washing. 
As can be seen in FIG. 2, the opposite pitches of screws 13 and 14 define 
areas of overlap 15 on the surface of inner chamber 12. Within the areas 
of overlap 15 on inner chamber 12 are formed a plurality of perforations 
or holes 16, 16 through which wash water may flow. It can be seen from 
FIG. 2 that wash water contained in one of the outer compartments 17 can 
communicate only with the corresponding overlapping inner compartment 18 
because of the placement of the performations 16 only within the areas of 
overlap 15. Thus it is seen that wash water from one pair of corresponding 
overlapping inner and outer compartments cannot mix with wash water from 
adjacent pairs of compartments. 
The invention as illustrated in FIG. 2 has an inlet end generally indicated 
by the numeral 19 and a discharge end generally indicated by the numeral 
21. In the embodiment illustrated, laundry to be washed or treated is 
placed in first inner compartment 36 on inlet end 19 and wash water or 
other treatment media is introduced into first outer compartment 39 on 
discharge end 21. As washing machine 10 is rotated in a counterclockwise 
direction as viewed from inlet end 19, it can be seen from FIG. 2 that the 
laundry will be transferred by inner transfer screw 14 from inlet end 19 
to discharge end 21 and wash water will be transferred by the outer 
transfer screw 13 from discharge end 21 to inlet end 19. Although FIG. 2 
illustrates a particular pitch and direction of the transfer screws and 
operation is discussed assuming transfer is accomplished by 
counterclockwise rotation, it will be understood that other degrees and 
directions of transfer screw pitches as well as other transfer rotation 
directions will work equally well. 
FIG. 3 is a cutaway view of the invention taken along line BB in FIG. 2. 
This view shows the washing machine 10 and more clearly illustrates the 
definition of the areas of overlap 15 on the inner chamber 12. 
Perforations 16 are shown formed in the areas of overlap 15 defined by 
outer compartments 17 and inner compartments 18. As can be seen in FIG. 3, 
perforations 16, 16 are confined to the overlapping areas on chamber 12. 
FIGS. 4a through 4d are a series of end elevation cutaway views of the 
invention taken generally along line AA in FIG. 3 illustrating the 
operation of a preferred embodiment of the invention. These figures show 
the locations of the wash water and the laundry at 4 stages of the cycle 
of washing machine 10. Illustrated in the figures is washing machine 10 
having a generally cylindrical outer chamber 11. Inner chamber 12 is shown 
mounted in and spaced from outer chamber 11 and one wall of inner transfer 
screw 14 and outer transfer screw 13 are shown. The particular embodiment 
illustrated in this series of figures shows a generally concave floor 
member 22 which is impervious to the wash water and that extends along the 
length of washing machine 10. Floor member 22 is rigidly attached along 
its edges 41 to the inside of outer chamber 11 such that the line of 
attachment is impervious to the wash water. Floor member 22 closely 
approaches the bottom of inner chamber 12 generally near the middle of 
floor member 22. A dry well 24 is defined between the convex side of the 
floor member and the inside wall of the outer chamber 11. Dry well 24 may 
be used as a space in which to house electrical connections or plumbing 
and may be provided with access doors or ports through the outside chamber 
without affecting the operation of the washing machine. FIGS. 4a through 
4d show cross sections of generic electrical or plumbing conduit 42. 
Also shown in the embodiment of the invention illustrated in FIGS. 4a 
through 4d is an inwardly convex ceiling member or bulge 23 formed in the 
top of inner chamber 12. FIG. 4a shows washing machine 10 in its normal or 
rest or reference position, and laundry 44 and wash water 43 are shown 
generally as they would be with washing machine 10 in this position. FIGS. 
4b and 4c show the locations of the laundry and wash water near the two 
extreme extents of an oscillation range. FIG. 4d shows the location of the 
laundry and wash water near the midpoint of a transfer rotation of washing 
machine 10. 
OPERATION 
In operation, washing machine 10 is first loaded or filled with wash water 
or other treating media by supplying wash water into the first compartment 
39 in the space between the outer and inner chambers 12 and 11, 
respectively. Washing machine 10 is rotated through a complete circle in 
the counterclockwise direction until it is in the rest or normal position 
as illustrated in FIG. 4a. Sufficient wash water has been added to each 
compartment so that in the rest position, laundry 44 is adequately wetted 
by wash water 43 so that it may be properly washed. Washing machine 10 is 
then oscillated through a predetermined angular range for a number of 
cycles as shown generally in FIGS. 4b and 4c. As washing machine 10 is 
oscillated, laundry 44 is agitated in wash water 43. Conventional ribs may 
be provided in the inner compartments if desired to aid in the agitation 
of the laundry. In addition, in the preferred embodiment illustrated in 
FIGS. 4a through 4d, as washing machine 10 oscillates through the normal 
position of FIG. 4a, the wash water rests on floor member 22 where it is 
raised above the bottom of outer chamber 11 and flows through perforations 
16 into inner compartment 18. As the oscillation continues to its extreme 
limits as illustrated in FIGS. 4b and 4c, wash water gradually rolls off 
of floor member 22 until it rests on the inside wall of outer chamber 11. 
It is thus apparent that as washing machine 10 oscillates from extreme to 
extreme, wash water will be forced alternately into and out of inner 
compartment 18 and consequently into and out of laundry 44 contained 
therein. In addition, the level of the wash water is raised and lowered. 
This raising and lowering of wash water level in addition to the agitation 
of the laundry as washing machine 10 oscillates produces improved washing 
action over prior art washing machines. 
At the end of a predetermined number of oscillations, it is desired to 
transfer the laundry to the next compartment in the inner chamber for the 
next wash cycle. This is accomplished by rotating washing machine 10 
through a complete circle in the counterclockwise direction so that it is 
again in the rest position illustrated in FIG. 4a. During this rotation, 
the laundry is transferred by inner transfer screw 14 to the next 
compartment toward end 21 and wash water is transferred by transfer screw 
13 to the next compartment between inner chamber 12 and outer chamber 11 
toward end 19. At approximately the midpoint of the transfer rotation, the 
laundry rides over the ceiling member 23 as shown in FIG. 4d. This causes 
the laundry to be raised somewhat with respect to the wash water level so 
that excess wash water is drained into the outer compartment before the 
laundry is transferred to the next inner compartment. The wash and 
transfer process is repeated until the laundry has traversed the length of 
washing machine 10 and emerges from end 21 where it will typically be 
removed and transported to dryers or other treatment stations. 
Several functions of the invention become apparent from the detailed 
description and operation set out above. The first function is the raising 
and lowering of the wash water level in the inner compartments during the 
wash cycle oscillations by virtue of floor member 22. This wash water 
action results in improved washing action. Another function is the raising 
of the laundry with respect to the wash water during a transfer rotation 
so that excess wash water is drained from the laundry before it is 
transferred to the next wash compartment. A function of the washing 
machine as described above is that during each transfer rotation, laundry 
is transferred one compartment in a first direction and wash water is 
transferred one compartment in the opposite direction. Thus the wash water 
is transferred, not to the next laundry compartment, but to the next one 
thereafter. In other words, a particular batch of water contacts the 
laundry in alternate, not adjacent, laundry compartments. The laundry, 
therefore, comes into contact with and is washed by only every other 
reservoir of wash water. This allows washing of different colors of fabric 
at the same time by alternating colors in the inner compartments. The 
inner compartments might, for example, be loaded alternately with red 
laundry, white laundry, red laundry, etc. and the wash water that comes 
into contact with the red laundry will never mix with the wash water that 
comes into contact with the white laundry, nor will it ever contact the 
white laundry. 
The present invention is also very efficient in terms of the amount of wash 
water required during operation. Prior art continuous flow machines 
require a continuous supply of wash water flowing into the laundry 
discharge end of the machine. Prior art multiple drum machines and tunnel 
type machines with impervious transfer screw walls require that the volume 
of wash water in each compartment be partially or completely drained and 
fresh wash water resupplied upon completion of each wash cycle. Each of 
these prior art designs requires large volumes of wash water for each wash 
cycle. 
During operation of the present invention, the volume of wash water 
contained in one outer compartment plus a smaller amount that remains in 
the wet laundry is transferred out of the machine upon each transfer 
rotation. To maintain the machine fully loaded with wash water, one need 
only add that same volume of fresh water to the first outer compartment at 
the other end of the machine at the end of each transfer rotation. 
Detergent or other treating chemicals can be added to the water before it 
is placed in the machine or it can be added in a conventional manner, 
e.g., through a central hub. As the laundry progresses down the length of 
the machine, it comes into contact with fresher and fresher water, so that 
at the discharge end, it is rinsed by fresh water in the last compartment. 
Because of this unique arrangement, it is possible to perform wash and 
rinse cycles without having to empty the water out. 
Although the invention has been described in the form of a preferred 
embodiment, many modifications, additions and deletions may be made 
thereto without departure from the spirit and scope of the invention as 
set forth in the claims.