GB2039003A - A water level control arrangement for dishwashers - Google Patents

Abstract

The arrangement includes a two- stage level control valve 48 disposed in a valve housing installed downstream of a water fill valve 42. The valve member 66 is moved into and out of engagement with the valve housing by an actuating arm 84 which is in operative engagement with a stem 56 of a float 90 positioned in the dishwasher tub 26. When the water level in the tub approaches a predetermined washing level, the float rises in the tub to a position whereat the valve is moved to a sealing position by inlet water pressure, thereby terminating further flow to the dishwasher tub. When the water is drained from the tub, the float stem moves the arm 84 to release the water pressure exerted against the sealed valve through a port located within the valve member 66. Further movement of the float stem causes the arm 84 to contact the wall of the port in the valve member 66 to tilt the latter into open position. <IMAGE>

Description

SPECIFICATION Mechanically operated level control for a dishwater Modern automatic dishwashers generally include automatic control of in-flow of water from the water supply line into the machine. This automatic control is typically provided by a timer which causes a fill valve to be opened at the approprate point in the machine cycle for a predetermined time interval, allowing water flow into the dish-washer tub during this interval.

These "time fill" arrangements require close tolerances of both the timer mechanism and the water fill valve. That is, it is normally desirable to integrate the timing mechanism and the water fill valve such that the changes in line pressure, which vary with the time of day and from locality to locality, are adequately compensated to prevent overfill and/or underfill conditions. Overfill results in a waste of energy and underfill normally causes poor washing performance.

These automatic control arrangements taught by the prior art also create the possibility of a flooding condition being reached when water overflows from the tub and out of the machine which may cause damage. Such a flooding condition may occur for a variety of reasons, such as failure of the fill valve, over-pressure line conditions, a clogged dishwater drain, etc. Many dishwater designs accordingly provide for some arrangement for flood control. In some of these designs a failsafe mechanism is incorporated into the electrical control which will correct flood level conditions occurring during the machine cycle. Some failure modes, however, such as a mechanical failure of the valve, may occur at any time, not only during the machine operation.

Thus, it is desirable to have 24-hour flood protection. For example, in U.S. Pat. 3,894,555, a flood control feature is disclosed in which a float is mounted within the dishwater tub which acts to de-energize a secondary electrically operated valve installed downstream from the fill valve. If a flood level occurs in the tub, the float rises to the flood level and acts to operate an associated switch to open the circuit to the secondary flood control valve, causing closing of the valve and cessation of the flow to the tub. The secondary valve however adds significantly to the expense of manufacture, since an addition relatively costly electrically operated valve is required.In addition, the reliability of electrically operated valves is less than mechanically operated valves and any failure of the valve will cause either malfunction of the dishwasher or defeat the flood control feature.

In accordance with the present invention there if provided a level control arrangement for a liquid in a container, the arrangement comprising a float which rises and falls with the level of liquid in the container, and a valve assembly operatively interconnected with the float and disposed in a supply line to the container, the valve assembly including a valve head engageable against a seat in a valve housing, the head having a pressure relief port located upstream of its seat-engaging surface, and the assembly being connected to the float by connecting means which, with the level of liquid changing in a predetermined direction, firstly open the pressure relief port to relieve the upstream pressure in the valve housing and then subsequently engage the wall of an axially extending internal passageway formed through a- stem integral with the valve head such that the head is displaced from its seat to open the valve.

A preferred embodiment of the invention provides a level control valve arrangement for a dishwater, the arrangement including a movable sealing valve body or plunger in a housing having an internal opening establishing fluid communication from a fill valve through the level control valve to the dishwasher tub. The valve body is provided with a head having a sealing surface and is adapted to be urged into sealing engagement with a valve seat surface in the valve housing by water line pressure to prevent flow into the dishwater. The valve includes a laterally extending stem portion in which is received an actuating connecting arm which is operative to sealingly engage with a pressure relief port located in the valve head. The actuating arm is in operative engagement with a float stem connected to a float disposed within the dishwasher tub.The normally open level control valve permits water to enter the dishwater tub whenever the fill valve is actuated in response to a timing device. As the water and therefore the float rises in the tub, the actuating arm responsive to the float position permits the valve head to seal against the valve housing when the float reaches a predetermined level. When the washing fluid is drained from the dishwasher, the float lowers causing the valve stem to move the actuating arm thereby relieving the line pressure against the pressurized side of the sealing valve through the pressure relief port. Further lowering of the float stem against the actuating arm causes the arm to engage the sealing valve stem, thereby opening the valve for the next fill sequence.

FIG. 1 is a fragmentary view of a dishwater in front elevation shown in partial section to depict the relationship of the components of one form of the present invention to the dishwasher structure.

FIG. 2 is a view in partial section of the major components of one form of the level control arrangement according to the present invention as shown in FIG. 1.

FIGS. 3 and 4 are partial sectional views of the sealing valve and associated housing and connecting member depicting the sealing valve in its closed and pressure relief stages of operation, respectively.

Referring to the drawings, and particularly FIG.

1, a conventional dishwater 10 is depicted into which is incorporated the level control arrangement according to the present invention.

The dishwater illustrated is of the built-in cabinet style, installed between adjacent kitchen cabinetry 12. The dishwasher 10 includes an inner frame 14 to which is mounted the outer cabinet panel 16 which provides access to the operating components. Front mounted door 18 provides access to the interior 20 of the dishwasher.

In the interior of the dishwasher 20 are mounted one or more racks 22 adapted to receive dishware items to be washed. Such racks 22 are mounted on rollers 24 for in and out movement for convenient loading of the dishware items.

The lower region of the interior 20 is comprised of a tub 26 which acts to collect the water introduced into the machine and directed in a high pressure spray at the dishware items. The washing action ic carried out by means of a rotary spray arm 28 into which is circulated water under high pressure in order to wash and rinse the dishware items disposed in racks 22.

The water collected in tub 26 is directed through an inlet fitting 30 to the inlet side of a pump 32, driven by an electric motor 34.

The outlet 36 of pump 32 communicates with internal flow passages to provide the high pressure circulation to the rotary spray arm 28 during the wash and rinse cycles. After the wash and rinse cycles, the water in tub 26 is pumped via drain outlet 38 to a plumbing drain.

An automatic fill arrangement is provided for introducing the water from the hot water connection into the machine. This arrangement conventionally includes a hot water pipe shown partially at 40 which is in communication with the hot water supply. The hot water pipe 40 is in fluid communication with a fill valve assembly 42 which is solenoid operated to establish a timed interval of communication at the appropriate points in the machine cycle with a fill hose 44. Fill hose 44 extends upwardly along the dishwasher cabinetry and is placed in communication with a fill nozzle fitting 46 which directs the hot water into the interior of the machine during the fill cycle.

The level control arrangement 48 according to the present invention, acts to mechanically provide the proper volume of water necessary for the wash and rinse cycles by termination of water flow from the fill valve assembly 42 to the tub 26 whenever a predetermined optimum amount of water has been admitted to tub 26. Level control valve assembly 48 is mounted below the float assembly 50 by a plurality of screws 52 adapted to engage with boss members 54 protruding from the tub 26. The assembly is located such that float stem 56 is received within the housing 58 of the level control means 48 as is better seen in FIG. 2.

The fill valve assembly 42 and the level control assembly 48 are interconnected by a hose 60.

The level control arrangement as seen in FIG. 2 consists of a combination of a two-stage level control valve assembly 48 and a float assembly 50. The level control valve 48 is in fluid communication with the fill hose 44 and the fill valve assembly 42. A short length of hose 60 joins the outlet fitting 62 of the fill valve assembly 42 and an inlet fitting 64 of the level control valve 48.

The outlet of the level control valve 48 is secured to the fill hose 44 to thus be placed in fluid communication with the fill circuit downstream of the fill valve assembly 42.

The level control valve 48 consists of the valve housing 58 within which is movably mounted a sealing plunger or valve body 66. The valve - housing 58 is formed with a relatively large diameter inlet chamber 68 which receives a sealing head portion 70 of the valve 66. A stem 72 of the valve body or plunger 66 extends into an elongated passage 74 of housing 58 which is in communication with the inlet chamber 68.

Passage 74 has a larger diameter than the stem 72 to allow water flow between the stem 72 and the passage 74 and to allow valve 66 to be tilted from its axis without engagement of stem 72 with the passage 74. Sealing head 70 is maintained in position in the inlet chamber 68 by a plurality of circumferentially spaced webs 76 and by abutment of the conically shaped shoulder 73 with the upstream terminus of passage 74. In the normally open position, water flows around the sealing head 70 and into the passage 74 with the sealing valve 66 held in position as shown in FIG. 2.

Received within a passageway 78, which extends laterally of the valve 66, is a connecting or actuating arm 80 as is better seen in FIG. 3. The actuating arm 80 has an enlarged terminal end 82 and a laterally extending portion 84 which abuttingly engages the float stem 56. End 82 has an integral conically extending shoulder 86 which is received in sealing engagement with a complementary conically formed pressure relief port 79 at the upstream terminus end of passage 78. The latter feature is better seen in reference to FIG. 4. End 82 also has a spring engagement shoulder 83 extending axially into chamber 68 for operative engagement and location of spring member 87. Spring 87 is designed to close valve 66 in the absence of any vertical force applied by stem 56 and in the absence of adequate line pressure for reasons discussed below.The upstream surface dimension of end 82 transverse to the axis of member 80 is substantially less than the upstream surface dimension of head 70 so that a relatively low downward force applied by float stem 56 against arm extension 84 is all that is required to bleed or relieve the pressure in chamber 68. Thus, presently available dishwater floats (i.e. relatively small and therefore light weight) may be used to provide the forces required to open valve 66 as will be described below.

In reference to FIG.4, it can be seen that the connecting arm extension 84 engages with the downstream terminal end of passage 78 of valve plunger 66 which upon further downward movement of float stem 56 causes plunger 66 to pivot about its seal engagement surface 71 at the top thereof, thereby opening the valve to the eventual position shown in FIG. 2. The first pivotal motion of shoulder 86 of actuating arm 84 about the aperture 79 of the plunger 66 may be designated as the pressure relief or first stage of operation, as shown in FIG. 4, and the further pivotal motion of plunger 66 about its sealing engagement surface 71 to the open position shown in FIG. 2 may be designated as the second stage of valve operation.

One skilled in the art will appreciate that the effective inlet water pressure received from the fill valve assembly 42 acts on the sealing head 70, thereby urging the sealing plunger 66 to the right as viewed in FIG. 3. The valve sealing surface 71 provided on the opposite face of the sealing head 70 from the direction of water pressure is adapted to engage an annular surface 88 formed on the end wall of the inlet chamber 68 such that upon movement into engagement therewith, the Water flow downstream of the flow control valve 66 is terminated. The sealing plunger 66 is maintained in its unseated-open position shown in FIG. 2 by the reaction of the float stem 56 against the actuating arm extension 84 which in turn pivots plunger 66 as was previously described.

The float stem 56 moves with a float 90 positioned in the bottom of tub 26, the float stem 56 passing through the interior opening 92 of a float guide 94. Float guide 94 extends upwardly above the predetermined wash level indicated in phantom as line 96 such that water will not flow through the interior opening 92 through which the float stem member 56 enters.

A seal or rolling diaphragm 98 is provided in the plunger housing 58 which prevents the water from passing out between the float stem member 56 and the plunger housing 58.

Surrounding the float 90 is a protective float housing 100 with inlet cutouts 102 provided to enable the water to pass into the interior of the float housing 100. Float 90 is provided with an annular valve chamber 104 with an inner opening 106 provided adjacent the float guide 94 to enable venting of the air and allowing the water level to thereby rise to the interior 108 of the float housing 100. The float guide 94 also insures guiding movement of the float to prevent tipping.

The relative weight and buoyancy of the float 90 is such that it will not rise in the housing appreciably until the predetermined wash level indicated at line 96 is approached. At this point, the buoyancy force moves the float 90 vertically upwardly permitting the actuating arm 84 to also rise in response to both the decreased force applied to the valve stem 56 and the line pressure applied against valve head 70. The water pressure thus acts on the sealing head 70 to force the same into sealing engagement with the valve sealing surface 88 to shut off further water in-flow to the dishwasher. The buoyant force is increased by the annular valve chamber 104 and may be contributed to by buoyancy of the material itself by employing a molded plastic material with specific gravity less than one.

In the event fill valve 42 develops a "dripping" leak when the dishwasher is in an idle mode, i.e.

when valve 66 is in the open position as shown in FIG. 2, the water collected in tub 26 may raise float 90 to a level where float stem 56 will tend to become disengaged from arm 84. This could cause a "flood" problem since the line pressure would probably not be sufficient to close valve 66.

However, spring 87 has been included to close valve 66 if this condition should occur.

Accordingly, it can be seen that an entirely mechanically operated level control arrangement is provided which does not require operation of the electrical controls of the dishwasher. This level control arrangement provides the proper level of washing liquid regardless of variances in line pressure and regardless of the tolerances associated with either the timer or the fill valve and its related controls. Further, with the inlet water pressure creating the valve sealing action, flood conditions are prevented from occurring, regardless of whether these are electrical or mechanical failures or some other condition occurs such as a clogged drain.

It can be seen that this design achieves the above-recited objects of the invention, producing a relatively simplified but reliable and mechanical level control arrangement while simultaneously providing against flooding, which arrangement may be incorporated at a relatively low cost.

Claims (11)

1. A level control arrangement for a liquid in a container, the arrangement comprising a float which rises and falls with the level of liquid in the container, and a valve assembly operatively interconnected with the float and disposed in a supply line to the container, the valve assembly including a valve head engageable against a seat in a valve housing, the head having a pressure relief port located upstream of its seat-engaging surface, and the assembly being connected to the float by connecting means which, with the level of liquid changing in a predetermined direction, firstly open the pressure relief port to relieve the upstream pressure in the valve housing and then subsequently engage the wall of an axially extending internal passageway formed through a stem integral with the valve head such that the head is displaced from its seat to open the valve.

2. A dishwasher comprising an electrically operated fill valve for controlling the flow of water into a water collecting tub, an electrically operated drain valve for draining the tub, and means for controlling the water level in the tub, the level control means comprising a float means disposed within the bottom region of the tub for up and down movement in response to changes in the water level in the tub; control valve means interposed in the water supply to the tub downstream of the fill valve means and including a valve head movable against a seat in a valve housing, the valve head having a pressure relief port upstream of its seat engagement surface, and means operatively interconnecting the control valve means and the float means, the connecting means including a member disposed within the valve head and operative to open the pressure relief port to relieve the upstream pressure in the housing in a first stage of operation, the member being further operative to engage the wall of an axially extending passageway through a stem integral with the valve head to open the valve in a second stage of operation in response to downward movement of the float means as the tub is being drained.

3. The dishwasher of Claim 2 wherein said valve head and valve seat are in sealing engagement when said float means is at a predetermined level.

4. The dishwasher of Claim 2 or Claim 3 wherein said valve housing includes an inlet chamber in fluid communication with said fill valve means, said valve head being disposed within said chamber, and wherein said housing includes a bore in fluid communication with said chamber, said valve stem being disposed within said bore.

5. The dishwasher of Claim 4 wherein said connecting member includes: an end portion movable into and out of sealing engagement with said pressure relief port; and an integral actuating arm operatively engaged with said float means and extending laterally through said valve stem and said bore.

6. The dishwasher of Claim 5 wherein the dimension of said end portion of said connecting member transverse to its axis is substantially less than the upstream surface dimension of said valve head.

7. An arrangement according to Claim 1 wherein said float means includes a float stem member secured to said float and extending downwardly into the interior of said valve housing, said float stem having a portion thereof normally engaging said connecting means to actuate the valve.

8. An arrangement according to Claim 7 wherein said valve head has an axial opening permitting a member of the connecting means to freely pivot transverse to said passageway, said member extending through said axial opening and being in pivotal and sealing engagement with said head whereby the upstream pressure exerted against said head is allowed to be relieved through said housing as said connector member pivots about said opening.

9. An arrangement according to Claim 8 wherein the stem extends into a bore of the housing and wherein the connector member.

extends into the bore through the axial passageway in said stem, whereby, after relieving the upstream pressure, further pivotal movement of the connector member engages said stem and thereby displaces the head out of engagement with said valve seat.

10. An arrangement according to Claim 1 wherein said valve housing includes an inlet chamber and a bore extending out of said inlet chamber, said stem extending with clearance into said bore, and wherein said float includes a member extending into said bore and into engagement with a member of said connector means engaging said stem to cause tilting of said head to preclude sealing engagement of the head with said valve seat surface when said float moves in a first direction, and wherein upon movement of said float in a second direction, said member is moved out of engagement with said stem to enable movement of said head to said sealing position.

11. A level control arrangement according to Claim 1 and substantially as herein described with reference to the accompanying drawings.