US3835880A

US3835880A - Dishwasher fill system

Info

Publication number: US3835880A
Application number: US00387522A
Authority: US
Inventors: R Hoffman; C Wright
Original assignee: Motors Liquidation Co
Current assignee: Motors Liquidation Co
Priority date: 1973-08-10
Filing date: 1973-08-10
Publication date: 1974-09-17
Anticipated expiration: 1991-09-17

Abstract

A domestic dishwasher is provided with a combined time and fill level control system which insures a proper fill level throughout a wide range of reasonably available domestic water supply pressures, guards against floods occasioned by a clogged drain and malfunctioning timer or water level switch and assures the advance of a dishwashing cycle irrespective of fill level where domestic water supply pressures are unreasonably low. The system includes a continuously running timer during fill having a timer controlled fill switch connected in series with a pressure actuated water level switch. The pressure switch controls fill when the dishwasher is supplied with water at normal supply pressures and guards against floods occasioned by a clogged drain and malfunctioning timer. The timer controls fill to advance the cycle by shunting the pressure switch when the dishwasher is supplied with water at unreasonably low supply pressures and guards against floods occasioned by a malfunctioning pressure switch by opening the fill switch.

Description

a States Hoffman et a1.

atent 1 DISHWASHER FILL SYSTEM [75] Inventors: Robert E. Hoffman, Centerville;

Carl J. Wright, Bellbrook, both of Ohio [73] Assignee: General Motors Corporation,

Detroit, Mich.

22 Filed: Aug. 10, 1973 21 Appl. No.: 387,522

Primary Examiner-William R. Cline Assistant ExaminerDavid R. Matthews Attorney, Agent, or Firm-Frederick M. Ritchie [57] ABSTRACT A domestic dishwasher is provided with a combined time and fill level control system which insures a proper fill level throughout a wide range of reasonably available domestic water supply pressures, guards against floods occasioned by a clogged drain and malfunctioning timer or water level switch and assures the advance of a dishwashing cycle irrespective of fill level where domestic water supply pressures are unreasonably low. The system includes a continuously running timer during fill having a timer controlled fill switch connected in series with a pressure actuated water level switch. The pressure switch controls fill when the dishwasher is supplied with water at normal supply pressures and guards against floods occasioned by a clogged drain and malfunctioning timer. The timer controls fill to advance the cycle by shunting the pressure switch when the dishwasher is supplied with water at unreasonably low supply pressures and guards against floods occasioned by a malfunctioning pressure switch by opening the fill switch.

5 Claims, 3 Drawing igures PAIENIEIISEP IIIIII $835880,

" satire 8F '2 15.2 \.WATER- WASH NORMAL TIMER CONTACTS I WNW- DRAIN HEATER I3 BY PASS =I RINSE I ST WASH 3 Z-ND 3-RD WASH & DRY

FILL VALVE 5 LINE 7 DET. DISP. 8

MOTOR I 9 WAS-H. A II RINSE COND- I4 U OPEN OPEN OR CLOSED 'ICLOSED I TIMER CYCLE CHART -i I DISHWASHER FILL SYSTEM This invention relates to a dishwasher fill system and, more particularly, to a fill system for insuring a proper fill level at all normal domestic water supply pressures, guarding against floods in the dishwasher and assuring that the dishwashing cycle will be completed even where the domestic water supply pressure is is low that a proper fill level is unattainable in a reasonable length of time.

Prior art fill systems have included a pressure switch which monitors the level of rising water during fill and terminates fill when a proper level is reached. With such systems, the timed cycle is interrupted and the timer motor remains off until the pressure switch turns it on again after a proper fill level is reached. Pressure switches have also been used in prior art dishwashers to sense an approaching flood condition and initiate a drain operation to prevent the flood. This invention is directed to a circuit arrangement including a pressure switch which both controls fill and prevents flood and including a timer which runs continuously during fill.

Accordingly, it is an object of this invention to provide a combined time and fill level control system for a domestic appliance, including a timer running during fill, which insures a proper fill level throughout a wide range of reasonably available domestic water supply pressures, guards against floods occasioned by a clogged drain, stuck timer or malfunctioning water level switch and assures the advance of a washing cycle irrespective of fill level where domestic water supply pressures are below the range of reasonably available pressures.

A further object in the fill system of the foregoing object is the provision in a dishwasher of a pressure switch in series with a fill valve controlling timer switch and in shunt with a recirculation pump controlling timer switch, wherein the pressure switch operates under normal water pressure conditions to terminate fill in less than the timed fill period.

An advantage of this invention, in addition to those inherent above, is the flexibility of a circuit embodying the invention to control fill by time alone.

Further objects and advantages of the present inven tion will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of the present invention is clearly shown.

IN THE DRAWINGS:

FIG. 1 is a side sectional view of a domestic dishwasher provided with the fill and flood control system of this invention;

FIG. 2 is a schematic wiring diagram for operating the dishwasher of FIG. 1 and including a circuit arrangement in accordance with this invention; and

FIG. 3 is a timer cycle chart showing the functional relationships of the timer switches in FIG. 2.

In accordance with this invention and with reference to FIG. 1, an improved dishwasher is illustrated generally. The dishwasher 20 is comprised of casing means 22 defining a dishwashing chamber 24 closed at the front thereof by dishwasher door 26 and having at the bottom thereof a depressed sump 28 leading to a pump motor assembly 30 which may be of the type taught in US. Pat. No. 3,265,31 l, issued Aug. 9, I966.

In general, the water distribution system includes a revoluble spray arm 32 beneath the lower rack 34 and a rotating spray column or spray tube 36 affixed to said spray arm and extending upwardly through a guard portion 38 of the lower rack facilitating removal of the lower rack from the dishwashing chamber. The spray tube has an outlet 40 adapted to project a spray generally upwardly through the suppott wire network of an upper dishrack 42. A reversible motor 44 in the pump motor assembly 30 directly drives the pump in one direction (WASH winding energized) to recirculate the water for washing or rinsing, and, when reversed (DRAIN winding energized), pumps the water to drain. A heater 50 is periodically energized throughout the timed operating cycle to provide recovery heat to the wash and rinse water and for adding heat to the dishwashing chamber for the drying cycle.

Various dispensers are periodically energized throughout the dishwashing cycle for providing desired washing or rinsing agents at effective points in the operating cycle represented by the timer cycle chart of FIG. 3. For instance, and with reference to FIG. 1, a solenoid actuated detergent dispenser 52 and a solenoid actuated water conditioner dispenser 54 may be positioned on the inside panel of dishwasher door 26 and electrically actuated through the control circuit of FIG. 2.

The dishwasher sump 2 8 is sized to contain substantially 2.7 gallons of water standing in a quiescent state at a normal fill level A. In accordance with this invention, however, sump 28 is also formed with a raised ledge or wall 60 defining along the upper edge thereof an overflow level B whereat the sump capacity is 5.5 gallons. Water levels above B will cause floods outside the dishwasher.

Water is supplied to sump 28 by means of a solenoid actuated water fill valve 64 through an opening 66 in the dishwashing chamber 24. Specifications for fill valve 64 call for supply of water at a rate of 1.6 gallons per minute from a domestic water supply having supply pressures between 20 pounds per square inch (psi) and 120 psi. A pressure actuated fill safety switch or water level switch 70 controls fill valve .64 and is adapted to terminate fill when normal fill level A is reached in the sump. Pressure switch 70 is designed to operate at heads of 4 inches of water in sump 28.

The dishwashing cycle of dishwasher 20 is controlled by a timer and a selector switch 82. Switch 82 may be of the push button type settable to provide a series of complete washing cycles entitled HEAVY WASH, NORMAL WASH, and RINSE AND HOLD, together with one CANCEU setting for resetting the selector switch. In accordance with FIG. 2, it should be understood that the various internal switches within the dashed outline of selector switch 82 move to a position opposite that shown when a cycle is selected which bears the number shown uncircled along-side each internal switch as follows:

1 HEAVY WASH 2 NORMAL WASH 3 RINSE AND HOLD 4 CANCEL Timer contacts listed in FIG. 3 are shown circled in FIG. 2. Thus, timer 80 includes a timer switch 84 operating between

timer contacts

1 and 2; a timer switch 86 operating between timer contacts} and 4; timer switch 88 operating to open and close timer contact 5; timer switch 90 operating between

timer contacts

7 and 8; timer switch 92 operating to open and close timer contact 9; timer switch 100 operating between timer contacts 11 and 12 to reverse the motor for wash recirculation or drain; and timer switch 102 operating between

timer contacts

13 and 14. A starting relay 104 operates to drop out the start winding (WASH or DRAIN) after the motor is up to speed.

OPERATION The invention will be described in connection with the fill system accompanying the selection of NOR- MAL WASH and beginning at 110 on the timer cycle chart and terminating at OFF. The dishwashing cycle is initiated through door switch 112 which closes when door 26 is closed. It should be understood that a rapid advance motor 114 will be energized through timer contact 3 in accordance with the timer cycle chart and

internal switches

115 and 120 in the selector switch 82 to advance the timer motor controlled cycle to the start point 110 for NORMAL WASH. At point 110, timer contact 3 opens and timer contact 4 closes. Timer motor 83 will then be energized from Ll, door switch 112, timer switch 86, timer contact 4, and

internal switches

120, 122, and 124 in selector switch 82. Thus, power supply conductor 126 remains energized throughout the NORMAL WASH cycle for supplying power to timer motor 83 and, if needed, water valve 64. At first, pump motor 44 will be operated in the drain direction (timer contact 12 closed) for purging the sump of any stagnant water. At cycle point 130 in the timer cycle chart, timer contact is closed to energize water valve 64 through water level switch 70. In this regard, it should be understood that the water level switch will have a first position 132 whenever the level of water in sump 28 is below normal fill level A. The water level switch has a second position 134 when the level of water in sump 28 is above normal fill level'A.

Fill water will start to enter the sump through inlet 66. If the pressure of the domestic water supply connected to the fill valve 64 is in a normal range of 30 to 60 psi, approximately 2.7 gallons of water will be supplied at the rate of 1% gallons per minute in 1.8 minutes and the fill valve will be deenergized when the water level switch moves to its second position 134. The dishwashing cycle is now ready to advance from the till cycle portion (designated F on the timer cycle chart) to the recirculation cycle portion (designated R on the timer cycle chart). Thus, power supply conductor 126 is connected to pump motor 44 through the water level switch and timer switch 92 closed on timer contact 9. Start relay 104 is energized and pump motor 44 will be connected through timer contacts 11 and the WASH start winding to operate in the recirculation direction.

The domestic water supply may be available at pressures as low as four to five psi and as high as 120 psi. This invention is adapted throughout a dishwashing cycle to terminate fill and start recirculation just as soon as the normal water level A is reached. The flow rate of the water valve is such that with normal supply pressures (30-60 psi), water level switch 70 will move to its second position to start the pump in approximately half the time allotted for fill. Thus, as water supply pressures increase, the recirculation cycle portion is extended to use more and more of the time allotted for the fill cycle portion. On the other hand, where the domestic water supply pressure is so low that normal water level A cannot be reached in a reasonable time (less than 4-5 psi), this invention is adapted to advance the dishwashing cycle to its completion (OFF) with whatever lesser amount of water is available in the sump.

In accordance with the foregoing principles, timer is adapted to provide a NORMAL dishwashing cycle having fill cycle portions 1400, 140C, 1401/. and l40e followed consecutively by recirculation cycle portions 1420, 142b, 1420, 142d, and 1420. A predetermined timed fill period of approximately 3 minutes is selected in the design of the timer cam during which timer switch 88 remains closed on timer contact 5. This fill period is of sufficient duration to provide a normal fill level A with water supply pressures as low as 4-5 psi but is of insufficient duration to cause the fill level to reach the overflow level B with high water supply pressures up to 120 psi. Of course, the duration selected for the predetermined period will depend on the overflow capacity of the dishwasher sump, i.e., the greater the capacity, the longer the predetermined timed period may be.

Immediately following each fill cycle portion and consecutive therewith are the respective recirculation cycle portions. Recirculation is normally initiated when water level switch 70 moves to its second position 134 or, if water supply pressure is low, when timer switch 90 moves to close timer contact 7 at cycle points a, 150b, 1506, 150d, and l50e. Thus, timer contact 7 will initiate the recirculation cycle portion if the pressure switch doesnt. This assures that the dishwashing cycle will advance to OFF irrespective of the water level in sump 28.

Even when the water level switch 70 malfunctions (stuck in first position 132), there is flood protection. Timer 80 is designed to actuate timer switch 88 and open timer contact 5 at the end of a predetermined fill period. As aforesaid the duration of such period is selected so that, even with high water supply pressures, the fill level will not exceed flood level B. Therefore, if the water level switch 70 cannot terminate fill, timer switch 88 will. In either event, the dishwasher is protected against flooding.

Timer contact 9 is included as an enabling switch to prepare pump motor 44 for energization. For this reason, timer contact 9 is closed during the fill cycle portion both before timer contact 7 closes and before water level switch 70 would normally move to its second position 134. Preferably, timer contact 9 is closed midway through the fill cycle portion.

While the embodiment of the present invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted. An understanding of other functions in the diswashing cycles is not necessary to a full understanding of the present invention. Such other functions, however, are disclosed in the wiring diagram of FIG. 2 as interpreted by the timer cycle chart of FIG. 3.

What is claimed is:

l. A positive water fill, flood prevention and cycle advance system for a dishwasher having a sump with an overflow level, fill valve means adapted for supplying a water level to the sump from a domestic supply of water available at pressures normally between about 30 pounds per square inch and 60 pounds per square inch but occasionally at below normal pressures to about 4 pounds per square inch and at above normal pressures to about 120 pounds per square inch, a pump motor for recirculating the water supplied and a timer for controlling said fill valve means and said pump motor in a dishwashing cycle including consecutive cycle portions of fill and recirculation, said timer including means for continuous energization thereof throughout said cycle portions, said system including a first timer switch in series with said fill valve means and controlled by said timer for a predetermined period to effect a water level in said sump above normal but below overflow when said water valve means is adapted for supplying water from a domestic supply of water at normal and above normal pressures, a pressure switch having a first position in series with said first timer switch for enabling the supply of water to the sump and movable to a second position in series with said pump motor when the water level in said sump reaches normal to terminate the supply of water to said sump irrespective of the timer control of said first timer switch thereby to prevent floods and to energize said pump motor for changing said fill cycle portion to said recirculation cycle portion during said predetermined period, a second timer switch in series with said pump motor and said pressure switch in its second position and controlled by said timer before said pressure switch is movable to its second position and before the end of said predetermined period to enable the energization of said pump motor for said recirculation cycle portion as soon as the pressure switch moves to its second position whereby said recirculation cycle portion may be extended by the amount of time before the end of said predetermined period that said supply of water to said sump is terminated, and a third timer switch in series with said pump motor and said second timer switch and in shunt with said pressure switch, said third timer switch controlled by said timer to bypass said pressure switch and energize said pump motor through said second timer switch thereby to advance the dishwashing cycle irrespective of the position of said pressure switch or a below normal water level in said sump when said water valve means is adapted for supplying water from a domestic supply of water at below normal pressures.

2. A positive water fill, flood prevention and cycle advance system for a domestic appliance having a sump with an overflow level, fill valve means adapted for supplying a water level to the sump from a domestic supply of water available at pressures normally between about 30 pounds per square inch and 60 pounds per square inch but occasionally at below normal pressures to about 4 pounds per square inch and at above normal pressures to about 120 pounds per square inch, a pump motor for recirculating the water supplied and a timer for controlling said fill valve means and said pump motor in a washing cycle including consecutive cycle portions of fill and recirculation, said timer including means for continuous energization thereof throughout said cycle portions, said system including a first timer switch in series with said fill valve means and controlled by said timer for a predetermined period to effect a water level in said sump above normal but below overflow when said water valve means is adapted for supplying water from a domestic supply of water at normal and above normal pressures, a pressure switch having a first position in series with said first timer switch for enabling the supply of water to the sump and movable to a second position in series with said pump motor when the water level in said sump reaches normal to terminate the supply of water to said sump irrespective of the timer control of said first timer switch thereby to prevent floods and to energize said pump motor for changing said fill cycle portion to said recirculation cycle portion during said predetermined period, thereby to extend said recirculation cycle portion by the amount of time before the end of said predetermined period that said supply of water to said sump is terminated, and a second timer switch in series with said pump motor and in shunt with said pressure switch, said second timer switch controlled by said timer at the end of said predetermined period to bypass said pressure switch and energize said pump motor thereby to advance the washing cycle from said fill cycle portion to said recirculation cycle portion irrespective of the position of said pressure switch or a below normal water level in said sump when said water valve means is adapted for supplying water from a domestic supply of water at below normal pressures.

3. The positive water fill, flood prevention and cycle advance system of claim 2 wherein said sump is adapted to contain substantially 5.5 gallons at the overflow level thereof, said fill valve means is adapted to pass water at substantially 1.6 gallons per minute at normal and above normal pressures, and said predetermined period is substantially three minutes.

4. The positive water fill, flood prevention and cycle advance system of claim 3 wherein said pressure switch moves to its second position to terminate the supply of water to said sump when said sump has been supplied with substantially 2.7 gallons to the normal water level thereof.

5. The positive water fill, flood prevention and cycle advance system of claim 2 wherein said pressure switch moves to its second position to terminate the supply of water to said sump in approximately half the total time allotted for said predetermined period when said water valve means is adapted for supplying water from a domestic supply of water at normal pressures.

Claims

1. A positive water fill, flood prevention and cycle advance system for a dishwasher having a sump with an overflow level, fill valve means adapted for supplying a water level to the sump from a domestic supply of water available at pressures normally between about 30 pounds per square inch and 60 pounds per square inch but occasionally at below normal pressures to about 4 pounds per square inch and at above normal pressures to about 120 pounds per square inch, a pump motor for recirculating the water supplied and a timer for controlling said fill valve means and said pump motor in a dishwashing cycle including consecutive cycle portions of fill and recirculation, said timer including means for continuous energization thereof throughout said cycle portions, said system including a first timer switch in series with said fill valve means and controlled by said timer for a predetermined period to effect a water level in said sump above normal but below overflow when said water valve means is adapted for supplying water from a domestic supply of water aT normal and above normal pressures, a pressure switch having a first position in series with said first timer switch for enabling the supply of water to the sump and movable to a second position in series with said pump motor when the water level in said sump reaches normal to terminate the supply of water to said sump irrespective of the timer control of said first timer switch thereby to prevent floods and to energize said pump motor for changing said fill cycle portion to said recirculation cycle portion during said predetermined period, a second timer switch in series with said pump motor and said pressure switch in its second position and controlled by said timer before said pressure switch is movable to its second position and before the end of said predetermined period to enable the energization of said pump motor for said recirculation cycle portion as soon as the pressure switch moves to its second position whereby said recirculation cycle portion may be extended by the amount of time before the end of said predetermined period that said supply of water to said sump is terminated, and a third timer switch in series with said pump motor and said second timer switch and in shunt with said pressure switch, said third timer switch controlled by said timer to bypass said pressure switch and energize said pump motor through said second timer switch thereby to advance the dishwashing cycle irrespective of the position of said pressure switch or a below normal water level in said sump when said water valve means is adapted for supplying water from a domestic supply of water at below normal pressures.