[0001] The present invention relates to a dishwasher filtration and soil collection system,
and more particularly to a system for automatically purging a filter and soil collection
system in a dishwasher to remove accumulated soils.
[0002] Typical domestic dishwashers in use today draw wash liquid from a sump at the bottom
of a wash tub and spray the wash liquid within the wash tub to remove soils from dishes
located on racks in the tub. In an attempt to improve performance and efficiency,
some dishwashers employ a system for separating soil out of the recirculating wash
liquid and for retaining the soils in a collection chamber. Frequently, a filter screen
is used to retain soil in a soil collection chamber. U.S. Pat. No. 5,165,433, for
example, discloses a dishwasher system including a centrifugal soil separator which
sends soil laden wash liquid into a soil container whereupon the soil laden wash liquid
passes through a fine filter disposed in the wall of the soil container.
[0003] Inherent in the system described in the '433 patent, and in any fine mesh filter
screen system in a dishwasher, is the problem of screen clogging by food soils removed
from the dishes. Typically, backwash jets are directed against the filter in an attempt
to clear the filter and prevent clogging. Heavy soil loads, however, can result in
screen clogging in spite of backwash jets.
[0004] Screen clogging can adversely affect the dishwasher's cleaning ability, causing poor
washability and indirectly causing increased water and energy consumption. Moreover,
the build-up of pressure behind the screen may increase - to a maximum determined
by the ability of the pump supplying soil laden wash liquid against the screen - and
result in soil embedding into the screen such that it is difficult to subsequently
remove the soils from the screen.
[0005] Some attempts have been made to develop a dishwasher wash system which is capable
of dealing with heavy soil loads and avoid filter clogging. U.S. Pat. No. 4,559,959
discloses a dishwasher wherein soil load is measured by monitoring pressure in a soil
collection chamber in which soils are retained after the wash liquid passes through
a filter mesh. If the pressure exceeds a predetermined limit, indicating that the
filter mesh is clogged, the wash liquid is completely purged by draining all of the
wash liquid out of the tub and refilling the tub with fresh water. The '959 patent
provides for a maximum of three complete purges at the beginning of the dishwasher
cycle. Additionally, the number of purges required is monitored and that information
is used to control the subsequent wash cycle - selecting the appropriate cycle for
the soil load of the dishes.
[0006] Concerns over dishwasher water and energy consumption make complete purges of wash
liquid from a tub undesirable. Accordingly, some dishwasher systems utilize purges
which only partially drain the dishwasher tub. For example, U.S. Pat. No. 4,346,723
discloses a dishwashing system wherein soils are collected in a bypass soil collector.
The soil collector may be purged by draining small amounts of wash liquid in "spurts"
during an early wash period by selectively opening and closing a drain valve.
[0007] U.S. Pat. No. 5,223,042 discloses a method of washing dishes wherein during the wash
cycle a portion of the washing solution is drained from the bottom of the tub to remove
soils. The wash solution is subsequently replenished with fresh water having a volume
equal to the volume of the discharged wash solution.
[0008] U.S. Pat. No. 5,429,679 includes a soil collection system wherein wash liquid is
sent into a filtration chamber and then returned to the tub sump through a filter.
After the first wash cycle, a portion of wash liquid, approximately 1 gallon out of
the total 2.3 gallons of wash liquid, is sent to drain and then replaced by adding
fresh water to the tub.
[0009] The above described systems all include several drawbacks. One of the most significant
is that, for all of these references, a relatively large quantity of water is drained
during each purge. Moreover, several of the above references teach interrupting the
wash operation during each drain purge such that no spray is directed against the
dishes while wash liquid is being purged. Another problem with the above described
systems is one of soil redeposition wherein soils, collected in the soil collection
chamber prior to each purge, are redeposited onto the dishes during the purge cycle.
[0010] In addition to the inadequacies of the prior art in dealing with clogging filter
screens, there exists a need for an improved food particle sizing system in a dishwasher.
Modem dishwashers are sold under the promotion that dirty dishes can be loaded into
the dishwasher with a minimum of preliminary rinsing or cleaning. In order to fulfill
this promise, many dishwashers are equipped with internal food processor or garbage
disposal systems. Current food processors or "food choppers" typically includes a
straight blade confined within a cylindrical housing adjacent a sizing plate. Typically,
the blade is mounted on the output shaft of the dishwasher motor and rotates as the
wash impeller rotates.
[0011] The problem associated with this currently available design is in its inability to
process tough or fibrous foods such as corn skins. Specifically, corn skins have been
observed wrapping around the leading edge of a straight blade wherein they are held
against the blade by the force of the blade moving through the water. When food particles,
such as corn skins, are retained against the blade, they are not efficiently passed
through the sizing plate and into the soil accumulator. As a result, the skins or
other fibrous food may remain in the food chopper housing after the wash water has
been drained and are often carried out of the sump late in the wash cycle and redeposited
on the dishes. As a result, difficult soils such as corn skins are never removed at
all due to the inability of currently available food choppers to cut these fibrous
soils into small pieces which can be filtered out in the accumulator system.
[0012] Another problem associated with the currently available food choppers is the accumulating
of soils against the inside surface of the housing which surrounds the blade. As the
blade rotates within the housing, the food is often thrown against the inside surface
of the housing and retained there during the wash cycle. Obviously it would be preferable
to have all food or "soil' move through the blade region such that the soils may be
chopped and pass through the sizing plate wherein the soils may be separated and collected
in a soil accumulation system.
[0013] Accordingly, there is a need for a dishwasher with improved soil chopping capabilities.
[0014] In accordance with the present invention, there is provided a dishwasher as defined
in claim 1.
[0015] The dishwasher may further include a drain conduit fluidly connecting the sump to
the drain pump. A control valve is provided for preventing fluid flow from the dishwasher
sump to the drain pump during the accumulator purge operation while the wash pump
is operating. The control valve is operated in response to fluid pressure created
by the wash pump.
[0016] The dishwasher has further include an improved food chopping system having a curved
chopping blade as opposed to a straight blade. The chopping blade is curved in a direction
away from its rotation. Therefore, tough, fibrous foods that are not easily cut slide
off the curved end of the blades only to be chopped again by the oncoming opposing
half of the blade. Additionally, in order to avoid the problem of soil accumulation
along the inside walls of the housing that surrounds the blade, inwardly protruding
deflector ribs are provided which approach, but do not engage the curved end of the
blades. The deflector ribs increase the turbulence of the fluid flow around the inside
surface of the housing thereby substantially reducing soil accumulation along the
inside surface of the housing.
Figure 1 is a perspective view of a dishwasher including a soil separation and collection
system in accordance with the present invention.
Figure 2 is a schematic illustration of the soil separation and collection system
of the present invention and embodied in the dishwasher shown in FIG. 1.
Figure 3 is a top view of the pump system of the dishwasher shown in FIG. 1.
Figure 4 is a diametric sectional view taken along line IV-IV of FIG. 3, illustrating
fluid flow during soil accumulator purging.
Figure 5a is a diametric sectional view taken along line V-V of FIG. 3, showing the
control valve in a closed position.
Figure 5b is a partial sectional view illustrating the control valve in an open position,
again taken along line V-V of FIG. 3.
Figure 6 is a transverse sectional view taken substantially along line VI-VI of FIG.
4.
Figure 7 is a partial sectional view of the pump and soil collector system illustrating
an alternative drain pump embodiment for the present invention.
Figure 8 is a schematic representation of electrical circuitry for an electromechanical
embodiment of the dishwasher shown in FIG. 1.
Figure 9 is a schematic representation of the control elements for an electronic embodiment
of the dishwasher shown in FIG. 1.
Figure 10 is a flow chart illustrating the operation of an alternate embodiment of
the dishwasher shown in FIG. 1 having a microprocessor control means.
[0017] In accordance with the invention as shown in the drawings, and particularly as shown
in FIG. 1, an automatic dishwasher generally designated 10 includes an interior tub
12 forming an interior wash chamber or dishwashing space 14. The tub 12 includes a
sloped bottom wall 16 which defines a lower tub region or sump 18 (FIG. 4) of the
tub. A soil separator and pump assembly 20 is centrally located in the bottom wall
16 and has a lower wash arm assembly 22 extending from an upper portion thereof. A
coarse particle grate 24 permits wash liquid to flow from the bottom wall 16 to soil
separator 20 while preventing large foreign objects from entering the pump system.
[0018] The basic constructional features of the soil separator are explained in US Patent
5803100 entitled "Soil Separation Channel for a Dishwasher Pump System". In that application,
the operation of a centrifugal soil separator and the construction of a soil separator
and collector are fully explained.
[0019] Turning to FIGS. 2, 3 and 4, it can be seen that the soil separator/pump assembly
20 includes a wash pump 28 having a wash impeller 32 disposed within a pump chamber
30 defined by a pump housing 31. The pump housing 31 is supported by a pump base 33.
During a wash cycle, the wash impeller 32, driven by motor 34, draws wash liquid from
the sump 18 through a pump inlet 36, provided between the pump housing 31 and pump
base 33, and pumps wash liquid up through a main pump outlet 38 into the lower spray
arm 22. A first portion of wash liquid is sprayed from the lower spray arm 22 against
dishes supported on a lower dishrack 40 and a second portion of wash liquid is directed
toward an upper spray arm 42. Wash liquid is repeatedly recirculated over the dishes
for removing soils therefrom.
[0020] Once soils are removed from the dishes, they are washed down into the sump 18, drawn
into the pump inlet 36 whereupon the soils encounter a chopping region 68 defined
by annular wall 69 surrounding a chopper assembly 70 for chopping and reducing the
size of soil particles which enter the pump chamber 30. Many of the basic constructional
features of the chopper assembly are explained in U.S. Pat. No. 4,319,599, entitled
"Vertical Soil Separator for Dishwasher". The chopper assembly 70 includes a sizing
screen 72 and a chopper 74 which is urged against a downwardly facing shoulder 32a
of the wash impeller 32 by a coil spring 76. The upper distal end of the coil spring
76 extends radially outwardly into a groove provided in the chopper 74 and a lower
distal end of the coil spring 76 extends into and is driven in rotation by a blind
hole provided in drive hub 77.
[0021] As shown in FIG. 6, the chopper 74 includes a pair of outwardly extending, curved
chopping blades 74a which are provided with sharp cutting edges 74b for comminuting
soil particles that are trapped on the sizing screen 72 so that they may be reduced
in size and subsequently pass through the sizing screen openings. The chopper 74 is
driven in the rotational direction illustrated by arrow 79 such that soils which contact
the cutting edges 74b and wrap about the chopping blades 74a are driven by the force
of the water acting against the rotating chopper 74 to slide off the blade ends. Food
soils swirling within the chopping region beyond the outer edges of the chopping blades
74a are driven back into the path of the blades 74a by deflector ribs 78 inwardly
extending from the annular wall 69.
[0022] Referring now back to FIGS. 2 and 4, it can be understood that after being chopped
and sized by the chopper assembly 70, the soils are drawn, along with the wash liquid,
into the pump chamber 30. Within the pump chamber 30, under the action of the rotating
wash impeller 32, the soils are centifugally separated and a sample of wash liquid
having a high concentration of entrained soils is directed to flow from the pump chamber
30 through a sample outlet 43 into a soil collector 45 comprising an annular soil
separation channel 46 and a soil accumulator 50. The sample outlet 43 is illustrated
as an annular guide chamber 44 having a bottom opening 47 through which soils flow
into the soil separation channel 46. Accordingly, the soil laden wash liquid is directed
to flow into the soil separation channel 46 which has top wall formed from a filter
screen 48. As the soil laden wash liquid proceeds within the separation channel 46
in an annular path, water passes upwardly through the filter screen 48 and back into
the sump 18 leaving the soils within the separation channel 46. Within the soil separation
channel 46, the velocity of the remaining wash liquid slows and the soils settle into
the soil accumulator 50.
[0023] During the wash cycle, the filter screen 48 is repeatedly backflushed. As the lower
wash arm 22 rotates, pressurized wash liquid is emitted from downwardly directed backflush
nozzles. Means may be provided for forming a fan-shaped spray from the flow of wash
liquid through the backflush nozzles. As the lower wash arm rotates, this fan shaped
spray sweeps across the filter screen 48 providing a backwashing action to keep the
screen clear of soil particles which may impede the flow of cleansed wash liquid into
the sump 18.
[0024] As described above, in spite of backflushing, in conditions of a heavy soil load,
the filter screen 48 may become clogged with food soils. When this occurs, wash performance
is impaired and pressure within the soil accumulator 50 increases. This pressure increase
is sensed by a pressure sensor 52 associated with a pressure tap tube connected to
a pressure dome 53 provided above the soil accumulator 50 such that the pressure sensor
52 measures pressure within the soil accumulator 50. The pressure sensor 52 can be
either an analog device or a digital device. When the pressure in the soil accumulator
exceeds a predetermined limit pressure, indicative of a clogged screen mesh 48, a
drain pump 54 is energized to clear the screen mesh. The drain pump 54 draws wash
liquid, highly concentrated with soils, from the soil accumulator 50 through drain
conduit 55 and pumps it past a check valve 56 through drain hose 58 to drain. When
the pressure in the accumulator is lowered below the predetermined limit pressure
the drain pump is deenergized. The duration of time during which the drain pump 54
is energized to clear the accumulator 50 and the screen mesh 48 is referred to as
purging or a purge period.
[0025] In this manner, the soil separation and collection system of the present invention
is purged of soils. It can be understood, moreover, that since the drain pump 54 is
separate from the wash pump 28, the purging of soils from the soil accumulator 50
and soil separation channel 46 can be accomplished while the wash pump impeller 32
continues to recirculate wash liquid through the dishwashing space 14.
[0026] It should be noted that for this type of plumbing configuration it is necessary to
maintain a minimum drain head pressure that is greater than the trip pressure of the
pressure switch. Otherwise, it is possible that the pressure build-up in the accumulator,
associated with the clogging of the filter, will be great enough to force the accumulator
contents past the drain pump if the head pressure is less than the trip pressure,
resulting in all the water being eventually depleted from the dishwasher. Also, the
water could be siphoned from the dishwasher the first time the drain pump is turned
on. One solution would be to establish a loop in the drain tube 58 sufficient to provide
the necessary pressure head and add a check valve 57 to the top of the drain tube
58 and have the check valve 57 open to the inside of the dishwasher to permit equalization
of the air in the drain tube with the air in the tub.
[0027] As an alternative to the above described drain pump system, the present invention
may utilize a drain pump driven by the wash pump motor in a manner similar to the
drain pump described in U.S. Pat. No. 4,319,599. In such a system, the pressure sensor
52 may be operated to control a drain valve associated with a drain line downstream
of the drain pump such that when the filter screen 48 becomes clogged, the drain valve
is opened to allow the drain pump to clear the accumulator. This type of system may
have some undesirable leakage from the pump chamber into the drain pump area but would
still provide beneficial results.
[0028] Turning now to FIGS. 5a and 5b, it can be understood that in addition to drawing
wash liquid from the soil accumulator 50, the drain pump 54 can drain the sump region
18 by drawing wash liquid through a drain port 62. However, to purge the accumulator
50 as quickly and effectively as possible, it is necessary to hydraulically isolate
the accumulator 50 from the rest of the dishwasher when the drain pump is purging.
Accordingly, during the wash cycle, when the wash impeller 32 is recirculating wash
liquid throughout the interior wash chamber 14, the drain port 62 is closed by a pressure
operated control valve system 60 such that the sump 18 is separated from the drain
pump when the wash pump 28 is operating.
[0029] The control valve system 60 may be any type of system responsive to pressure generated
by the operation of the wash pump 28 but is illustrated as a movable valve stem 61
supporting a plug seal 63. The valve stem 61 is supported along the underside of the
pump housing 31. The valve stem 61 includes an upper pressure surface 61a secured
to a flexible diaphram 65. A coil spring 67 is compressed between a spring retainer
69 and the backside of the upper pressure surface 61a such that the upper pressure
surface 61a is urged upwardly into a cavity 71. The pressure cavity 71 is fluidly
connected to the annular guide channel 44 via a conduit 73 such that the control vavle
60 is responsive to the the pressure generated by the wash impellor 32.
[0030] Accordingly, when the wash impeller 32 is recirculating wash liquid within the pump
chamber 30, the valve stem 61 is forced downwardly, as shown in FIG. 5a, responsive
to the pressure in cavity 71 such that the plug seal 63 operates to seal the drain
port 62. When the wash impellor 32 is not being rotated or when there is insufficient
wash liquid to pressurized the cavity 71, the valve stem 61 is biased upwardly such
that plug seal 63 is raised above the drain port 62, as shown in FIG. 5b, to open
the drain port 62 when the wash pump 28 is not in operation.
[0031] As can be clearly seen in FIG. 5 and 5a, when the control valve 60 is closed, the
drain pump 54 only draws wash liquid from the accumulator 50 when it is energized
to purge soils, as illustrated by flow lines 64. It can be understood, therefore,
that when the drain pump 54 is energized during the wash cycle, the accumulator 50
and the soil separation channel 46 are purged very quickly which reduces the pressure
within the accumulator 50 and the soil separation channel 46 such that the backwash
nozzles 51 can clean the filter screen 48. As a result, the accumulator 50, the soil
separation channel 46 and filter screen 48 are cleared very quickly such that very
little water - as little as 0.1 liters per purge - need be sent to drain to achieve
an effective purge period.
[0032] Fluid flow through the soil separator and pump assembly 20 when the control valve
60 is allowed to open and the drain pump 54 is energized is shown in FIGS 4 and 5b.
Flow lines 66 illustrate the path of wash liquid drained from the sump through drain
port 62. At the same time, wash liquid is drained from the accumulator 50 through
drain conduit 55.
[0033] The control valve system 60 can be used to separate the sump 18 from the accumulator
50 during the initial portion of a drain cycle to avoid soil redeposition onto the
dishes. This can be accomplished by continuing to operate the wash pump 28 during
the early portion of the drain cycle to keep the control valve 60 in a closed position
such that wash liquid is initially drained only through the accumulator 50 wherein
the accumulator 50 is cleared of soils and rinsed by water entering from the sump.
After some period of time or when the wash pump 28 begins to starve, the motor 34
may be deenergized such that the control valve 60 opens.
[0034] It can be understood by one skilled in the art that the operation of control valve
system 60 allows for a thorough pump-out of wash liquid during drain such that little
wash liquid remains in the sump 18 at the completion of a drain cycle. It would be
possible, however, to provide an alternative embodiment of the present invention by
omitting the control valve system 60. In such an embodiment, all wash liquid would
be drained from the dishwasher through the soil accumulator 50.
[0035] In FIG. 2, described above, the drain pump 54 is shown as a separate element apart
from the main soil separator and pump assembly 20. As illustrated, the drain pump
54 would have a separate motor and could be energized independently of the wash pump
motor 34. FIG. 7 illustrates an alternative embodiment to this type of separate drain
pump system wherein the drain pump can be selectively energized separate from the
main wash pump system while still being driven by the wash pump motor 34.
[0036] In FIG. 7, the drain pump 130 comprises a drain impeller 131 which is supported within
a drain pump enclosure formed into the pump base 33'. The drain impeller 131 is driven
by a shaft 132 which has a portion extending below the pump base 33' to which a pulley
134 is secured. The pulley 134 is driven by belt 136 extending about a drive pulley
138 associated with the drive shaft of the main motor 34' and an idler pulley 140.
To energize the drain pump 130, the idler pulley 140 is moved by an actuator such
as a solenoid or wax motor (not shown) such that the belt 136 is tightened allowing
it to transfer torque to the pulley 134 from the drive pulley 138 for rotating the
drain impeller 131. In this manner, the drain pump 130 may be energized for purging
the accumulator or draining the dishwasher, as described above, by energizing the
actuator associated with the idler pulley 140.
[0037] The present invention may be beneficially employed in a dishwasher having either
an electromechanical control scheme utilizing a conventional timer or an electronic
control scheme utilizing a microprocessor.
[0038] Components of an electromechanical embodiment of the present invention are shown
in FIG. 8. Current to the dishwasher is provided through lines L1 and L2. An interlock
door switch 80 ensures that the dishwasher is deenergized when the door is opened.
The dishwasher is started in its operating cycle by manipulation of a control knob
82. The control knob 82 is rotated a few degrees to turn the shaft of a timer motor
84 whereby cam 86 causes switch 88 to close, thereby energizing the timer motor 84.
The advancing timer motor 82 rotates cams 90, 92, 94, 96 and 98 for selectively controlling
switches 100, 102, 104, 106 and 108, respectively.
[0039] When switch 102 is positioned to complete the circuit through contact 110, the drain
pump 54 is energized whenever pressure switch 116, operatively associated to pressure
dome 53, closes in response to pressure in the accumulator 50 exceeding the predetermined
limit pressure. Similarly, the drain pump 54 is deenergized when the pressure in the
accumulator 50 falls below the predetermined limit pressure and the switch 116 opens.
It can be understood that the drain pump 54 cycles on and off independently of the
timer motor 84 rotation such that very short purge intervals are possible. Moreover,
the drain pump 54 is energized independently of the wash pump motor 34.
[0040] The wash liquid sent to drain during each purge period may be replaced by having
cam 94 close switch 104 such that fill valve 118 is energized simultaneously with
the drain pump 54. During the machine fill portion of the dishwasher cycle, switch
104 is open and the fill valve 118 is energized through switch 106.
[0041] Alternatively, the wash liquid sent to drain during each purge period may also be
accounted for by simply supplying a small amount of additional water into the dishwasher
during the initial fill cycle wherein switch 104 and line 120 may be omitted from
the dishwasher circuit. This "overfill" approach is a realistic alternative, given
that only a small amount of wash liquid - as little as 0.1 liter - is sent to drain
during each purge period.
[0042] FIG. 9 illustrates an electronic control embodiment of the present invention utilizing
a microprocessor controller 120 which employs the control logic shown in FIG. 10.
[0043] Turning now FIG. 10, in steps 142 and 144, wash liquid is supplied into the dishwasher
tub to a predetermined level whereupon the wash pump 34 is energized. In step 145,
the controller 120 monitors the pressure within the accumulator 50 via input from
the pressure sensor 52 and stores the rate of pressure change (Pc). If the pressure
exceeds a predetermined limit, as shown in step 146, a purge routine 148 comprising
steps 150 and 152 is initiated. After the accumulator 50 has been purged and the filter
screen 48 is cleared, the drain pump 54 is deenergized in step 154. The drain pump
may be deenergized when the accumulator pressure falls below the predetermined limit
pressure. Alternatively, the drain pump may remain energized some predetermined time
after the accumulator falls below the predetermined limit pressure or until the accumulator
pressure reaches some predetermined reset pressure, lower than the predetermined limit
pressure.
[0044] In steps 156, 158 and 160 the controller 120 counts the number of times (Np) the
purge routine is initiated and sums the time (Tp) the drain pump was energized during
the preceding purge periods. Based on that information, the controller 120 determines
whether additional wash liquid is required to replace the quantity of water sent to
drain during the prior purge routines. The purge routine 148 is initiated as frequently
as required in response to pressure sensor 52 and is performed while the wash pump
continues to recirculate wash liquid within the dishwasher. At the end of the initial
wash period, the wash pump is deenergized and the wash liquid is drained from the
dishwasher, as shown in steps 162, 164 and 166.
[0045] Following the initial wash period, the dishwasher cycle can be modified, as shown
in step 168, in response to gathered information - Pc, Tp or Np - indicative of the
quantity and type of soil. For example, the duration of the wash cycle length may
be increased when heavy soil load is sensed as determined by the number of purge routines
or additional fills may be added to the cycle. In this manner, the dishwasher is responsive
to the soil load for selecting the optimum wash cycle.
[0046] The present invention may be readily employed in a fully automatic manner to provide
a uniquely simple dishwasher cycle of operation. Specifically, the present invention
makes it possible to effectively wash dishes with a two fill cycle as compared to
present systems which typically require at least 5 fill cycles. In the two fill wash
cycle, during the first fill cycle the dishwasher is operated to wash the dishes wherein
the pump system is repeatedly purged until soil quantities in the wash liquid are
reduced to a very low level. The second fill cycle can then be used as the single
rinse cycle. Additionallly, if initial soil levels are so low that there is no resulting
accumulator pressure, as may occur with pre-rinsed dishes, the two fill cycle will
be used as the normal cycle.
[0047] It can be seen, therefore, that the present invention provides for a substantial
improvement in the efficiency of dishwasher operation. The present invention provides
a unique pump system which washes dishes in a manner superior to the dishwashers presently
available for sale while using substantially less energy and water than presently
available dishwasher systems. Specifically, the inventors calculate that the present
invention, if employed on all dishwashers in the United States (U.S.), would save
almost 24 billion gallons of water a year and almost 4 billion KWH's per year - based
on an assumption of 18 million dishwashers in use in the U.S. operated 300 times a
year (6 times a week for 50 weeks a year).
[0048] While the present invention has been described with reference to the above described
embodiments, those of skill in the Art will recognize that changes may be made thereto
without departing from the scope of the invention as set forth in the appended claims.
1. A dishwasher (10) having an interior wash chamber (14) receiving wash liquid and a
sump region (18) disposed at the bottom of the wash chamber, the dishwasher comprising:
a wash pump (28) having an intake (36) through which wash liquid is drawn from the
sump (18), the wash pump further having a main outlet (38) and a sample outlet (43);
a soil collector (45) receiving wash liquid from the wash pump through the sample
outlet (43), the soil collector having a screen (48) for passing filtered wash liquid
back into the sump region such that soils accumulate within the soil collector; and
a drain pump (54) fluidly connected to the soil collector to drain wash liquid from
the soil collector;
characterised in that a pressure sensor (52) is located in the soil collector (45) for sensing wash liquid
pressure within the soil collector; and
in that
the drain pump is arranged to operate in response to the pressure sensor sensing a
wash liquid pressure exceeding a predetermined limit pressure.
2. The dishwasher according to claim 1, wherein the soil collector (45) further comprises:
a soil accumulator region (50) for receiving wash liquid from the wash pump through
the sample outlet, the screen (48) forming a wall portion of the soil accumulator
region, and
wherein the pressure sensor (32) senses the pressure within the soil accumulator region
(50) and the drain pump draws wash liquid from the soil accumulator region.
3. The dishwasher according to claim 1 or 2, further comprising:
a drain port (62) fluidly connecting the sump region to the drain pump; and
a control valve (63) for selectively closing the drain port preventing fluid flow
through the drain port when the wash pump is operating.
4. The dishwasher according to claim 3, further wherein the control valve for preventing
fluid flow through the drain conduit is operated in response to fluid pressure created
by the wash pump.
5. The dishwasher according to claim 3 or 4, wherein the drain pump (54) is hydraulically
isolated from the wash pump (28) such that all wash liquid drained from the wash chamber
when the control valve is closing the drain port backflushes the screen and drains
through the soil collector.
6. The dishwasher according to any preceding claim, further comprising:
means for supplying a fill quantity of wash liquid into the wash chamber;
means for controlling the drain pump for purging soils from the soil accumulator such
that the quantity of wash liquid drained through the soil accumulator is substantially
less than the fill quantity supplied into the wash chamber.
7. The dishwasher according to any preceding claim, further comprising:
means for measuring the amount of wash liquid pumped from the soil collector to drain;
and
means for adding about the same amount of wash liquid into the wash chamber.
8. The dishwasher according to any preceding claim, wherein the wash pump (28) comprises:
a motor having a rotating shaft;
a wash impellor (32) being mounted on the rotating shaft; and
a blade (74) mounted on the rotating shaft below the wash impellor, the blade including
two curved ends, the curved ends curving away from a direction of rotation of the
shaft during the wash cycle.
9. The dishwasher according to claim 8, further wherein the blade is disposed, within
a cylindrical side wall having an inner surface, the inner surface of the cylindrical
side wall including inwardly protruding deflector ribs (78).
1. Geschirrspülmaschine (10) mit einer internen Spülkammer (14) zur Aufnahme der Spüllauge
und einem Sumpfbereich (18) am Boden der Spülkammer sowie mit:
einer Laugenpumpe (28) mit einem Zulauf (36), durch den Spüllauge aus dem Sumpf (18)
angesaugt wird, und einem Hauptablauf (38) sowie einem Probenauslass (43);
einem Schmutzsammler (45), der aus der Laugenpumpe vom Probenauslass (43) her Spüllauge
aufnimmt und der ein Sieb (48) aufweist, durch das gefilterte Spüllauge in den Sumpfbereich
zurückgeleitet wird, so dass Schmutz sich im Schmutzsammler sammelt; und
einer Abwasserpumpe (54) in Strömungsverbindung mit dem Schmutzsammler, durch die
Spüllauge aus dem Schmutzsammler ablassbar ist;
dadurch gekennzeichnet, dass
im Schmutzsammler (45) ein Drucksensor (52) angeordnet ist, mit dem der Laugendruck
im Schmutzsammler erfassbar ist; und dass
die Abwasserpumpe so eingerichtet ist, dass sie arbeitet, wenn der Drucksensor einen
vorbestimmten Grenzdruck erfasst.
2. Geschirrspülmaschine nach Anspruch 1, deren Schmutzsammler (45) weiterhin aufweist:
einen Schmutzsammelbereich (50) zur Aufnahme von Spüllauge vom Probenauslass der Spüllaugenpumpe,
wobei das Sieb (48) einen Wandteil des Schmutzsammelbereichs bildet;
wobei der Drucksensor (32) den Druck im Schmutzsammelbereich (50) erfasst und die
Abwasserpumpe Spüllauge aus dem Schmutzsammelbereich ansaugt.
3. Geschirrspülmaschine nach Anspruch 1 oder 2 weiterhin mit:
einem Ablassanschluss (62), der eine Strömungsverbindung vom Sumpfbereich zur Abwasserpumpe
herstellt; und
einem Steuerventil (60), mit dem der Ablassanschluss wahlweise schließbar ist, um
bei arbeitender Laugenpumpe eine Strömung durch den Ablassanschluss zu verhindern.
4. Geschirrspülmaschine nach Anspruch 3, bei der weiterhin das Steuerventil zum Verhindern
einer Strömung durch den Ablassanschluss ansprechend auf den von der Laugenpumpe erzeugten
Flüssigkeitsdruck betätigt wird.
5. Geschirrspülmaschine nach Anspruch 3 oder 4, bei der die Abwasserpumpe (54) von der
Laugenpumpe (29) hydraulisch getrennt ist derart, dass die gesamte Lauge, die aus
der Spülkammer abgelassen wird, wenn das Steuerventil den Ablassanschluss schließt,
das Sieb rückwärts durchspült und durch den Schmutzsammler abfließt.
6. Geschirrspülmaschine nach einem der vorgehenden Ansprüche weiterhin mit:
einer Einrichtung zum Einfüllen von Lauge in die Spülkammer und
einer Einrichtung zum Ansteuern der Ablasspumpe zum Ausspülen von Schmutz aus dem
Schmutzsammler derart, dass die Menge der durch den Schmutzsammler abgelassenen Lauge
wesentlich geringer ist als die der Spülkammer zugeführte Füllmenge.
7. Geschirrspülmaschine nach einem der vorgehenden Ansprüche, weiterhin mit:
einer Einrichtung, mit der die aus dem Schmutzsammler zum Ablauf gepumpte Laugenmenge
messbar ist; und
einer Einrichtung zur Zufuhr etwa der gleichen Menge Lauge zur Spülkammer.
8. Geschirrspülmaschine nach einem der vorgehenden Ansprüche, deren Laugenpumpe (28)
aufweist:
einen Motor mit einer rotierenden Welle;
ein auf die rotierende Welle aufgesetztes Laugen-Flügelrad (32); und
eine auf die rotierende Welle unter dem Laugen-Flügelrad aufgesetzte Klinge (74) mit
zwei gekrümmten Enden, die sich während des Spülzyklusses von einer Drehrichtung der
Welle hinweg krümmen.
9. Geschirrspülmaschine nach Anspruch 8, bei der weiterhin die Klinge sich in einer zylindrischen
Seitenwand befindet, die eine Innenwandfläche hat, und die Innenwandfläche der zylindrischen
Seitenwand einwärts vorstehende Ablenkrippen (78) aufweist.
1. Lave-vaisselle (10) ayant une cuve intérieure de lavage (14) qui reçoit un liquide
de lavage et une région de puisard (18) disposée au fond de la cuve de lavage, le
lave-vaisselle comprenant :
une pompe de lavage (28) ayant une prise d'eau (36) à travers laquelle un liquide
de lavage est aspiré à partir du puisard (18), la pompe de lavage ayant en outre une
sortie principale (38) et une sortie d'échantillon (43) ;
un collecteur de salissures (45) qui reçoit le liquide de lavage provenant de la pompe
de lavage à travers la sortie d'échantillon (43), le collecteur de salissures ayant
un tamis (48) destiné à refaire passer le liquide de lavage filtré dans la région
de puisard de telle sorte que les eaux usées s'accumulent à l'intérieur du collecteur
de salissures ; et
une pompe de vidange (54) raccordée de façon fluidique au collecteur de salissures
pour vidanger le liquide de lavage provenant du collecteur de salissures ;
caractérisé en ce qu'un capteur de pression (52) est situé dans le collecteur de salissures (45) afin de
détecter la pression du liquide de lavage à l'intérieur du collecteur de salissures
; et
en ce que
la pompe de vidange est agencée de façon à fonctionner en réponse au capteur de pression
qui détecte une pression de liquide de lavage dépassant une pression limite prédéterminée.
2. Lave-vaisselle selon la revendication 1, dans lequel le collecteur de salissures (45)
comprend en outre :
une région d'accumulateur de salissures (50) destinée à recevoir un liquide de lavage
provenant de la pompe de lavage à travers la sortie d'échantillon, le tamis (48) formant
une partie de paroi de la région d'accumulateur de salissures, et
dans lequel le capteur de pression (32) détecte la pression à l'intérieur de la région
d'accumulateur de salissures (50) et la pompe de vidange aspire le liquide de lavage
provenant de la région d'accumulateur de salissures.
3. Lave-vaisselle selon la revendication 1 ou 2, comprenant en outre :
un orifice de vidange (62) raccordant de façon fluidique la région de puisard à la
pompe de vidange ; et
une vanne de réglage (60) destinée à fermer de façon sélective l'orifice de vidange
afin d'empêcher un écoulement de fluide à travers l'orifice de vidange lorsque la
pompe de lavage est en fonctionnement.
4. Lave-vaisselle selon la revendication 3, dans lequel la vanne de réglage destinée
à empêcher l'écoulement de fluide à travers le conduit de vidange fonctionne en outre
en réponse à une pression de fluide créée par la pompe de lavage.
5. Lave-vaisselle selon la revendication 3 ou 4, dans lequel la pompe de vidange (54)
est isolée de façon hydraulique de la pompe de lavage (28) de telle sorte que tout
le liquide de lavage vidangé depuis la cuve de lavage lorsque la vanne de réglage
ferme l'orifice de vidange rince à rebours le tamis et est vidangé à travers le collecteur
de salissures.
6. Lave-vaisselle selon l'une quelconque des revendications précédentes, comprenant en
outre :
un moyen destiné à amener une quantité de remplissage de liquide de lavage dans la
cuve de lavage ;
un moyen destiné à commander la pompe de vidange afin de purger les salissures de
l'accumulateur de salissures de telle sorte que la quantité de liquide de lavage vidangé
à travers l'accumulateur de salissures est sensiblement inférieure à la quantité de
remplissage amenée dans la cuve de lavage.
7. Lave-vaisselle selon l'une quelconque des revendications précédentes, comprenant en
outre :
un moyen destiné à mesurer la quantité de liquide de lavage pompée à partir du collecteur
de salissures pour vidanger ; et
un moyen destiné à ajouter environ la même quantité de liquide de lavage dans la cuve
de lavage.
8. Lave-vaisselle selon l'une quelconque des revendications précédentes, dans lequel
la pompe de lavage (28) comprend :
un moteur ayant un arbre rotatif ;
une turbine de lavage (32) étant montée sur l'arbre rotatif ; et
une aube (74) montée sur l'arbre rotatif en dessous de la turbine de lavage, l'aube
comportant deux extrémités incurvées, les extrémités incurvées s'incurvant en s'éloignant
d'une direction de rotation de l'arbre au cours du cycle de lavage.
9. Lave-vaisselle selon la revendication 8, dans lequel l'aube est en outre disposée
à l'intérieur d'une paroi latérale cylindrique ayant une surface interne, la surface
interne de la paroi latérale cylindrique comportant des nervures de déviation (78)
faisant saillie vers l'intérieur.