Hydraulic Control System For A Washing Machine

Abstract

A dishwashing machine has two solenoid actuated fill valves within a water supply line, and pressure tap between the solenoid valves is connected to a normally closed pressure actuated drain valve within a drain line to provide for controlling the drain valve in response to selective actuation of the fill valves. The fill valves are controlled by a timer according to a predetermined sequence, and the downstream fill valve is also actuated by a centrifugal switch responsive to operation of the motor for the recirculating means.

Parent Case Text

Cross-References to Related Applications

This application is a continuation-in-part of now abandoned application Ser. No. 789,296, filed Jan. 6, 1969.

Description

BACKGROUND OF THE INVENTION

In the field of dishwashing machines such as disclosed in Geiger et al. U.S. Pat. No. 3,323,529, which issued to the assignee of the present invention, water is supplied to a tank defining a washing chamber through a line having a solenoid-actuated fill valve. The water is recirculated within the tank by a motor-driven recirculating pump connected to a reaction spray arm, and the water is removed from the tank by a drain pump which is driven either by the same motor driving the recirculating pump or by a separate motor. When the main recirculating pump and the drain pump are driven by the same nonreversing motor, it is common to employ a solenoid actuated drain valve in the drain line leading from the drain pump. The dishwashing machine also incorporates a motor-driven timer which controls the actuation of the fill and drain valves and the motor for each pump in accordance with a programmed cycle of operation.

In recent years, it has been found desirable to employ two solenoid-actuated fill valves in the water supply line to a dishwashing machine, especially in the water supply line to a machine which is permanently installed under a countertop. The purpose of the two solenoid-actuated fill valves is to prevent water from overflowing the dishwashing machine tank in case one of the fill valves accidentally leaks or sticks in an open position by a foreign particle received from the water supply line. While the second solenoid fill valve adds cost to the machine, it is believed that this cost is justified in a high-quality dishwashing machine in view of the fact that it is seemingly impossible to construct a solenoid-actuated fill valve which will never leak and which is impossible to stick in the open position.

SUMMARY OF THE INVENTION

The present invention is directed to an improved hydraulic control system which is ideally suited for controlling the drain of an automatic dishwashing machine as outlined above. The system utilizes the selective operation of the two separate solenoid-actuated fill valves in the water supply line to control the operation of a water pressure actuated device. In accordance with one embodiment of the invention, a normally closed pressure-actuated diaphragm valve is mounted within the drain line to protect against back draining or siphoning into the machine, and this diaphragm drain valve is actuated by the water pressure obtained by tapping the water supply line between the two solenoid-actuated fill valves. The drain valve is constructed to open when the upstream fill valve is open and the downstream fill valve is closed. However, when both the fill valves are open to supply water to the tank, the water pressure to the drain valve is reduced causing the drain valve to close. Furthermore, if the machine is stopped during draining when only the upstream fill valve is open, the downstream fill valve is momentarily opened to provide for closing of the drain valve and thereby assure that the drain water will not flow or siphon back into the wash chamber.

A primary advantage of a drain control system constructed in accordance with the invention is the elimination of a solenoid for actuating the drain valve without sacrificing the water overflow protection provided by the two solenoid fill valves in the water supply line and without sacrificing the protection against back flowing or siphoning of drain water into the tank. Furthermore, since the two solenoid fill valves and the drain valve are normally located in the same general area of an under-the-counter dishwashing machine, that is, in the lower front portion of the machine, it is within the scope of the invention to construct the fill valves and the drain valve within a common housing or body which reduces the overall production costs of the valves.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a side elevational view of a dishwashing machine with a portion broken away to illustrate somewhat diagrammatically a drain control system constructed in accordance with the invention; and

FIG. 2 is a schematic fluid diagram for operating the drain control system employed in the dishwasher shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawing, FIG. 1 shows a typical front loading type dishwashing machine including an outer cabinet indicated generally at 10 which encloses a tank 11 having a bottom 12 and defining a wash chamber 14. Access to the wash chamber 14 is provided by a door 15 operable between a vertical closed position and a horizontal open position and which is adapted to be sealed tightly against the tank 11 by actuating the latch 16. Tableware and food preparing articles are supported within the cleansing chamber 14 by one or more racks 17 which are adapted to be moved out over the door 15 when in the open position for convenient loading and unloading. While a front loading type dishwashing machine is illustrated, it is to be understood that the drain control system according to the invention may be employed in other types of dishwashing machines, as for example, a top opening portable dishwasher.

As shown in FIG. 1, the bottom 12 slopes downwardly towards the center so that the liquid collecting thereon drains into a sump 20 having a bottom wall 23. A main recirculating pump 25 is located within the sump 20 and has an inlet surrounded by an annular filter 26. The discharge of the pump 25 is connected to a conduit (not shown) which supports a rotatable reaction arm 28 having jet openings for spraying water upwardly over the articles supported by the racks 17.

A drain pump 30 is mounted on the bottom wall 23 of the sump 20 and is secured to the upper bearing bracket 31 of a motor 32. As shown in the aforementioned patent, the upwardly projecting shaft of the motor 32 drives the impellers of both the main recirculating pump 25 and the drain pump 30. Water is supplied to the chamber 14 through a fill line 35 which extends to a fill airgap 36 mounted on a sidewall of the tank 11. A pair of valves 38 and 40 each actuated by a corresponding solenoid 42, are mounted within the fill line 35, and both valves 38 and 40 have a common housing or body 44 which supports the two solenoids 42.

A normally closed pressure-actuated drain valve 45 is mounted within a drain line 46 connected to the drain pump 30, and the valve 45 includes a diaphragm actuator 48. Preferably, the valve 45 and diaphragm actuator 48 are enclosed within the body 44 with one side of the diaphragm connected by a line or passageway 52 to the fill line 35 between the fill valves 38 and 40. The other side of the diaphragm is open to atmosphere.

In operation, the motor 31 and the solenoids 42 of the fill valves 38 and 40 are automatically controlled according to a predetermined sequence or program by a motor driven timer 50 supplied with electrical power from lines L.sub.1 and L.sub.2. Water is introduced into the chamber 14 by opening both of the fill valves 38 and 40. When a predetermined amount of water has been supplied to the chamber 14, fill valves 38 and 40 are closed. After the water is circulated by the main pump 25 for the desired length of time, fill valve 38 is opened which pressurizes passageway 52 thereby pressurizing the diaphragm actuator 48 which opens the drain valve 45. After the water is removed from the tank, fill valve 40 is opened and the operation is repeated for another wash or rinse period. After the final drain when fill valve 38 is open and fill valve 40 is closed to open drain valve 45, fill valve 38 is closed and fill valve 40 is momentarily opened so that the pressure on the diaphragm actuator is released and drain valve 45 returns to its normally closed position when the dishwashing machine is not in use.

A centrifugally actuated switch 55 is mounted on the lower end of the motor 31 and is located within a line 56 which connects the power supply line L.sub.2 to the line which connects the timer 50 to the solenoid 42 for the downstream fill valve 40. A switch 58 is located within the line 56 and is actuated by operating the latch 16. When the latch handle is raised to permit opening the door 15, the switch 58 closes. When the door is locked, the switch 58 is open. Preferably, the switch 55 consists of back contacts on the centrifugal starting switch for the motor 31 and is normally open when the motor is stopped.

As mentioned above, the switches 55 and 58 function to prevent the drain valve 45 from remaining open in the event the door 15 is opened during a drain period when the upstream fill valve 38 is open and the downstream fill valve 40 is closed. That is, if the door 15 is open when water is being drained from the wash chamber, for example, to add a forgotten dish, the upstream fill valve 38 will close, but the downstream fill valve 40 will remain open momentarily by power supplied through the switches 55 and 58 until the speed of the shaft of the motor 31 drops to the speed when the centrifugal switch 55 opens. By bypassing the timer 50 to hold the downstream fill valve 40 open momentarily, water pressure within the line 52 is discharged through the valve 40 so that the drain valve 45 will close and thereby prevent drain water from back flowing or siphoning through the drain valve 46 and into the sump 20.

As another advantage, the drain control system of the invention eliminates the need for an additional solenoid to actuate the drain valve 45 as well as the noise which is produced by the drain valve solenoid. That is, the drain valve solenoid is replaced by a less expensive and quieter fluid pressure actuator 48 which, in effect, is controlled by the pressure differential across the fill valve 40. Furthermore, by incorporating all three valves 38, 40 and 45 and the diaphragm actuator 48 within the valve body 44, the production cost of the fill and drain valves is significantly reduced as well as the labor cost for installing the valves on the dishwashing machine. Moreover, the combination of the two fill valves 38 and 40 effectively eliminates the possibility of water overflowing the chamber 14.

While the form of apparatus herein described constitutes a preferred embodiment of the invention, it is to be understood that the invention is not limited to this precise form of apparatus, and that changes may be made therein without departing from the scope of the invention. For example, in place of the centrifugally actuated switch 55, the solenoid 42 for the downstream fill valve 40 might be energized independent of the timer cam actuated switch by a switch mechanically actuated by operation of the drain valve 45 or solely by the door latch switch 58. The latter method of actuation would require a solenoid 42 capable of continuous operation.

Claims

What is claimed is:

1. A dishwashing machine comprising a tank defining a chamber having rack means therein for receiving articles to be cleaned, a water supply line extending to said tank, first and second fill valves within said water supply line, said first fill valve being located upstream of said second fill valve relative to the flow of water within said supply line, means including a motor for circulating water within said chamber, means including a drain line for removing water from said chamber, a normally closed drain valve within said drain line, water pressure actuated means for operating said drain valve, means defining a water passageway connecting said pressure-actuated means to said water supply line between said first and second fill valves for controlling the operation of said drain valve in response to selected operation of said fill valves, timer means for actuating said motor and said fill valves according to a predetermined program, said drain valve being open when said first fill valve is open and said second fill valve is closed, said drain valve being closed when both said fill valves are either open or closed or when said first fill valve is closed and said second fill valve is open, and control means separate from said timer means for at least momentarily opening said second fill valve when said first fill valve is closed to assure a release of water pressure within said passageway when both said fill valves are closed.

2. A washing machine as defined in claim 1 wherein said latter control means comprises a centrifugally actuated switch operated by said motor.

3. A washing machine as defined in claim 2 wherein said switch is normally open when the shaft of said motor is stationary.

4. A washing machine as defined in claim 1 including a housing supporting both said fill valves and said water pressure actuated means.