Water level sensor and dishwasher having the same

A water level sensor and a dishwasher having the same are disclosed, in which water level is sensed for stable supply of washing water. The water level sensor includes a case including a first chamber formed therein, a first floater provided in the first chamber, ascending as water level ascends, and a first switch selectively pressurized by the first floater to avoid excessive supply of water.

This application claims the benefit of Korean Application No. P2004-47441 filed on Jun. 24, 2004, which is hereby incorporated by reference as if fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a dishwasher, and more particularly to, a water level sensor and a dishwasher having the same, in which level of washing waster is sensed.

2. Discussion of the Related Art

Generally, a dishwasher is to remove dirt on dishes by spraying washing water to the dishes at high pressure and dry the dishes.

The dishwasher includes a cabinet, a door opening and closing the front of the cabinet, a sump, and a pump.

The cabinet constitutes appearance of the dishwasher and is provided with a tub constituting a washing space.

A door is provided at the front of the cabinet to open and close the washing space, and racks are provided inside the tub to receive dishes. The sump is provided at the bottom of the tub to store washing water therein.

The pump is provided at the lower portion of the tub to pump the washing water stored in the sump at high pressure. A motor is provided at the rear of the pump to drive the pump.

The racks are divided into an upper rack provided in the upper space of the tub and a lower rack provided below the upper rack.

A top nozzle is provided at the upper portion of the upper rack while a lower nozzle is provided at the lower portion of the lower rack. An upper nozzle is provided between the upper rack and the lower rack.

The nozzles are connected with a water guide, and dishes received in the racks are washed by spraying the washing water through the nozzles at high pressure.

The washing water pumped by the pump is guided by the water guide provided at one side of the tub and is sprayed toward the dishes received in the racks through the nozzles.

Since the dishwasher requires an appropriate amount of washing water to wash dishes, it is necessary to develop a dishwasher in which excessive supply of washing water is avoided and failure due to leakage of washing water is prevented from occurring.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a water level sensor and a dishwasher having the same that substantially obviates one or more problems due to limitations and disadvantages of the related art.

An object of the present invention is to provide a water level sensor and a dishwasher having the same, in which water level is sensed for stable supply of washing water.

To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, a water level sensor includes a case including a first chamber formed therein, a first floater provided in the first chamber, ascending as water level ascends, and a first switch selectively pressurized by the first floater to avoid excessive supply of water.

The first floater is supported at a predetermined height from the bottom of the case.

The case includes a support supporting the first floater at a predetermined height.

The support is projected from either an inner wall of the case or the bottom of the case.

The first switch is pressurized by the first floater to input an excessive water supply signal.

The case further includes a second chamber formed at one side of the first chamber to connect with the first chamber.

The water level sensor further includes a second floater provided in the second chamber and a second switch selectively pressurized prior to the first switch by the second floater to input a water level signal.

The second switch inputs a leakage signal if it is released from its pressurized state as water level descends during water supply.

In another aspect, a dishwasher includes a sump storing washing water therein, and a water level sensor sensing water level of the washing water stored in the sump, wherein the water level sensor includes a case having a first chamber formed therein, a first floater provided in the first chamber, ascending as water level ascends, and a first switch selectively pressurized by the first floater to avoid excessive supply of water.

The first floater is supported at a predetermined height from the bottom of the case.

The case includes a support supporting the first floater at a predetermined height.

The support is projected from either an inner wall of the case or the bottom of the case.

The first switch is pressurized by the first floater to input an excessive water supply signal.

The case further includes a second chamber formed at one side of the first chamber to connect with the first chamber.

The dishwasher further includes a second floater provided in the second chamber and a second switch selectively pressurized prior to the first switch by the second floater to input a water level signal.

The second switch inputs a leakage signal if it is released from its pressurized state as water level of the sump descends during water supply.

The second switch inputs a leakage signal if it is released from its pressurized state as water level of the sump descends in a state that the dishwasher does not work.

The second switch is provided at a ceiling of the second chamber substantially flush with the first chamber, and the second floater is longer than the first floater.

The water level sensor is provided with a separate power terminal.

The dishwasher further includes a display displaying signals input by the first switch and the second switch.

The display includes an alarm portion alarming excessive water supply or leakage of water.

DETAILED DESCRIPTION OF THE INVENTION

A dishwasher according to the present invention will be described with reference toFIG. 1.

Referring toFIG. 1, a dishwasher100of the present invention includes a cabinet110constituting appearance, a tub120provided inside the cabinet110to form a dish washing space, and a door130provided at the front of the cabinet to open and close. At least one or more racks141and142are provided inside the tub120to receive dishes.

In more detail, the upper rack141is provided at the upper portion of the tub120while the lower rack142is provided at the lower portion of the tub120.

Rollers (not shown) are provided underneath the upper and lower racks141and142. The rollers are supported by rails (not shown) provided at inner sides of the tub120. Thus, the racks141and142are moved in front and rear directions by the rollers and the rails.

The tub120is provided with a sump151, a pump152, and a motor153at the lower side. The sump151stores washing water therein. The pump152is connected with the sump151and is driven by the motor153.

Further, a top nozzle160is provided above the upper rack141while an upper nozzle170is provided below the upper rack141. A lower nozzle180is provided below the lower rack142.

The top nozzle160, the upper nozzle170, and the lower nozzle180are connected with a water guide190that guides washing water pumped by the pump181. The top nozzle160downwardly sprays the washing water while the upper nozzle170and the lower nozzle180upwardly spray the washing water. Preferably, the upper nozzle170may spray the washing water up and down.

Meanwhile, an air brake (not shown) is provided at a side of the dishwasher100. The air brake supplies the washing water to the sump151and drains the washing water of the sump151.

The air brake is connected with a supply pipe (not shown) that supplies the washing water, and is provided with a flow meter that senses the amount of the supplied washing water.

The dishwasher100further includes a water level sensor200that senses the level of the washing water inside the sump151.

Hereinafter, the water level sensor200provided in the dishwasher of the present invention will be described with reference toFIG. 2toFIG. 5.

FIG. 2is a perspective view illustrating the water level sensor provided in the dishwasher according to the present invention,FIG. 3is a longitudinal sectional view illustrating the water level sensor shown inFIG. 2,FIG. 4is a longitudinal sectional view illustrating the state that water level inside the water level sensor ofFIG. 2reaches a first water level, andFIG. 5is a longitudinal sectional view illustrating the state that water level inside the water level sensor ofFIG. 2reaches a second water level.

The water level sensor200includes a case210, a first floater220provided inside the case210, and a first switch230pressurized by the first floater220.

A first chamber211is formed inside the case210to receive the first floater220, and a sump opening212is formed at a side of the case210. The sump opening212connects with the sump151to make water level of the sump151equal to that of the first chamber211.

A cover213is provided at the top of the case210to cover the case210.

Next, the first floater220ascends by means of the washing water as water level of the first chamber211ascends, so that it selectively pressurizes the first switch230.

The first switch230is provided at an upper side of the first chamber211, specifically, the ceiling of the case210, i.e., the bottom of the cover213constituting the ceiling of the first chamber211. The first switch230is selectively pressurized by the upper portion of the first floater220.

In other words, if the upper portion of the first floater220reaches the bottom of the cover213as the first floater220ascends by means of the washing water, the first switch230is pressurized by the first floater220to avoid excessive supply of the washing water.

In more detail, if the washing water stored in the sump151is about to overflow due to continuous supply of the washing water to the sump151, the first floater220ascends by means of the washing water inside the first chamber211connected with the sump151and the first switch230is pressurized by the first floater220.

Then, the first switch230inputs an excessive water supply signal to a controller (not shown), and the controller allows the washing water stored in the sump151to be drained out and/or stopped from being supplied.

If the first switch230is pressurized, a signal to drain the washing water stored in the sump151and/or stop supply of the same may directly be transmitted to a drainage or a water supplier provided at the air brake without through the controller.

Meanwhile, the first floater220is spaced apart at a predetermined height from the bottom of the case210.

The first chamber211is provided with a support211ato support the first floater220. The support211ais projected from either the inner wall of the first chamber211or the bottom of the first chamber211to prevent the first floater220from being operated in error due to contaminants between the first floater220and the inner wall of the first chamber211.

In the present invention, to support the bottom of the first floater220, the support211ais upwardly extended at a predetermined height in a state that its lower end is fixed to the bottom of the first chamber211. Alternatively, the support211amay horizontally be projected from both facing sidewalls of the first chamber211to support the lower portion of the first floater220.

In other words, the support211amay downwardly be extended at a predetermined length in a state that its upper end is fixed to the lower portion of the floater220.

Moreover, the case210further includes a second chamber214connected with the first chamber211.

The second chamber214is formed at one side of the first chamber211, and a second floater240is provided inside the second chamber214. The second floater240ascends by means of the washing water.

A second switch250is provided at the ceiling of the second chamber214and is selectively pressurized by the second floater240. The second switch250is pressurized prior to the first switch230to input a water level signal indicating that the washing water of the sump has reached a predetermined water level.

Under the condition that the first chamber211has the same height as that of the second chamber214, the second floater240is formed to be longer than the first floater220so that the second switch250is pressurized prior to the first switch230.

It is apparent that the first chamber211may be higher than the second chamber214so that the second switch250is pressurized prior to the first switch230.

The first chamber211and the second chamber214are partitioned by a first barrier wall215.

A first opening215ais formed at the lower portion of the first barrier wall215to connect the first chamber211with the second chamber214.

Meanwhile, a water supply chamber216connected with the first chamber211is formed at the other side of the first chamber211, i.e., at an opposite side of the second chamber214.

A washing water supply opening217is formed at the upper portion of the water supply chamber216to supply the washing water to the water supply chamber216. Since the sump opening212is formed at a lower side of the water supply chamber216, the washing water supplied to the water supply chamber216is supplied to the sump151through the sump opening212.

The first chamber211and the water supply chamber216are partitioned by a second barrier wall218. A second opening218ais formed at the lower portion of the second barrier wall218to connect the first chamber211with the water supply chamber216.

The aforementioned water level sensor200is provided with a separate power terminal260so that the power source is supplied thereto separately from the dishwasher.

The power terminal260is preferably spaced apart from at a predetermined distance from the washing water supply opening217to avoid leakage current.

Preferably, the cabinet110of the dishwasher is provided with a display (not shown) that displays signals input by the first switch230and the second switch250.

The display may be provided with an alarm portion that alarms excessive supply of washing water or leakage of washing water.

In the aforementioned present invention, if the second switch250is pressurized by the second floater240, the signal indicating that the washing water of the sump151has reached a predetermined water level is transmitted to the display through the controller or is directly input to the display.

If the water level inside the first chamber211and the second chamber214descends as the water level of the sump151descends during continuous supply of the washing water to the sump151, the second switch250is released from the pressurized state. In such case, the second switch250inputs a leakage signal to the controller or the display.

Furthermore, since the power source is supplied to the water level sensor in a state that the dishwasher does not work, the water level of the sump151descends in such state. Thus, the second switch250is released from the pressurized state. In this case, the second switch250inputs the leakage signal to the controller or the display.

The operation of the aforementioned water level sensor and the dishwasher having the same will be described with reference toFIG. 4andFIG. 5.

First, the operation of the water level sensor will be described.

If the water level of the sump151ascends as the washing water is supplied into the dishwasher through the air brake, the water levels of the first chamber211, the second chamber214and the water supply chamber216ascend to be flush with the water level of the sump151.

If the water level of the sump151reaches a predetermined water level, the second floater240pressurizes the second switch250to stably supply the washing water to the sump151. The signal indicating that the washing water has reached a predetermined water level is input to the display. The display displays water level information of the sump151.

In the present invention, the water level of the second chamber214, i.e., the level of the sump151at the time when the second switch250is pressurized is called a first level.

If the second switch250is released from the pressurized state while supply of the washing water continues, the second switch inputs the leakage signal to the display and the display displays such leakage information.

At this time, the leakage information may be displayed as an alarm signal through the alarm portion. Preferably, if the leakage signal is input, the washing water is stopped from being supplied and at the same time is drained.

Meanwhile, if the first floater220pressurizes the first switch230as the water level of the sump151is about to overflow due to continuous supply of the washing water without any leakage, the washing water stored in the sump151is drained and/or stopped from being supplied. At the same time, information on excessive supply of the washing water to the sump is displayed in the display.

The water level of the first chamber211, i.e., the water level of the sump151at the time when the first switch230is pressurized is called a second water level.

Next, if the washing water is sufficiently supplied to the sump151, the washing water stored in the sump151is pumped by the pump152connected to the motor153at high pressure. The washing water pumped at high pressure is sprayed from the top nozzle160, the upper nozzle170and the lower nozzle180under the guide of the water guide190.

The operation of the dishwasher will now be described in more detail.

First, a user opens the door130of the dishwasher100and draws the upper rack141and/or the lower rack142toward the front of the cabinet110.

After dishes are received in the upper rack141and/or the lower rack142and the door130is closed, the power source is applied to the dishwasher100. Then, the dishwasher100performs a washing step.

If the washing step is performed, the washing water is supplied to the sump151. If the washing water is stopped from being supplied to the sump151, the motor153is operated.

An impeller (not shown) provided inside the pump152and connected with the motor153is rotated by driving of the motor153. In this case, the washing water stored in the sump151is pumped and is supplied to the top nozzle160, the upper nozzle170, and the lower nozzle180along the water guide190.

Next, the washing water is sprayed toward the upper rack141and the lower rack142through the top nozzle160, the upper nozzle170, and the lower nozzle180to wash dishes received in the upper rack141and the lower rack142. The top nozzle160downwardly sprays the washing water, the upper nozzle170sprays the washing water up and down while rotating, and the lower nozzle180upwardly sprays the washing water.

If the washing step is finished, the washing water contaminated by the washing step is collected in the sump151and the contaminated washing water is filtered by a filter (not shown) to remove contaminants. The washing water is finally drained outside the dishwasher through a drain pump (not shown).

Furthermore, if the washing water is drained outside the dishwasher, clean water is supplied to the sump151through a washing water inlet (not shown). Afterwards, the above washing step is repeated several times. A rinsing step is then performed. If the rinsing step ends, a drying step is performed. The whole washing operation of dishes is finally finished.

The aforementioned water level sensor and the dishwasher having the same have the following advantages.

First, the water level sensor provided in the dishwasher enables stable supply of the washing water and prevents excessive supply of the washing water.

Second, since the water level sensor has no electrical sensor, failure due to leakage current is avoided.

Third, since the first floater is supported at a predetermined height from the bottom of the case, it is prevented from being operated in error due to contaminants on the bottom of the case.

Finally, since the water level sensor is provided with a separate power terminal, it is possible to detect whether there is leakage of the washing water even in case that the dishwasher is turned off.