Method for filling a wash tub of a dishwasher with water

Abstract

A method for filling a wash tub (12) of a dishwasher (10) with water, wherein the wash tub (12) comprises a water-collecting sump pot (16) that is fixed to an opening in its bottom and said method forms part of a program cycle for the operation of the dishwasher, said method comprising the subsequent steps of: (i) opening a water inlet (13) of the dishwasher and executing a static filling of the wash tub wherein a circulation pump of the dishwasher is kept deactivated, (ii) detecting a predetermined lower water level (22) inside the sump pot (16), and (iii) starting to measure the time for the static filling when said lower water level (22) is detected.

Claims

1. A method for filling a wash tub of a dishwasher with water, wherein the wash tub comprises a water-collecting sump pot that is fixed to an opening in its bottom and said method forms part of a program cycle for the operation of the dishwasher, said method comprising a step of: (i) opening a water inlet of the dishwasher and executing a static filling of the wash tub wherein a circulation pump of the dishwasher is kept deactivated, (ii) detecting a predetermined lower water level inside the sump pot, (iii) starting to measure the time for the static filling when said lower water level is detected, (iv) detecting a predetermined upper water level inside the sump pot and stopping the static filling, (v) determining a flow rate of the inlet water during the static filling basing on the duration of the static filling and on a known sump pot volume comprised between said upper water level and said lower water level of the sump pot, (vi) executing a percentaged filling of the wash tub after the upper water level of the static filling has been reached, wherein the circulation pump is kept deactivated and a predetermined percentaged water volume is added to the wash tub by opening the water inlet for an open time corresponding to said percentaged water volume, wherein said open time is calculated based on said percentaged water volume and on the inlet water flow rate determined during the static filling, (vii) switching on the circulation pump and keeping it running at a first pump speed, (viii) detecting an insufficient operational water level in the wash tub that is lower than a known first required operational water level that corresponds to full load operation of the circulation pump at said first pump speed, (ix) executing a dynamic filling of the wash tub while the circulation pump is running by opening the water inlet until said first required operational water level is detected inside the wash tub, wherein both the insufficient operational water level and the first required operational water level are detected by an analogue pressure sensor, and (x) subsequently adapting the filled-in amount of water in the wash tub to at least one further pump speed that is higher or lower than said first pump speed during the program cycle, wherein the pump speeds can be different in at least two steps of the program cycle and/or within at least two sub-steps of an individual step of the program cycle, wherein when the further pump speed is higher than said first pump speed, wherein an insufficient operational water level is detected that is lower than a known required operational water level that corresponds to full load operation of the circulation pump at said further pump speed, and said dynamic filling is executed while the circulation pump is running by opening the water inlet until said required operational water level is detected, wherein when said further pump speed is lower than said first pump speed, involving a step of an at least partial drainage of the water comprised in the wash tub and a subsequent step of executing a dynamic filling while the circulation pump is running by opening the water inlet until a required operational water level that corresponds to said further pump speed is detected, and wherein the circulation pump is maintained at or above said further pump speed during the at least partial drainage and the subsequent step of executing the dynamic filling.

2. The method according to claim 1, wherein at least one of the lower water level and the upper water level in the sump pot are detected by at least one pressure sensor, wherein at least one of a lower pressure that corresponds to the lower water level and a higher pressure that corresponds to the upper water level in the sump pot are measured by the at least one pressure sensor, wherein the at least one pressure sensor comprises the analogue pressure sensor.

3. The method according to claim 1, wherein the total water volume initially filled into the wash tub consists of said sump pot volume plus said percentaged water volume, said total volume being lower or equal to a first operational water volume that is required for full load operation of the circulation pump at a first pump speed.

4. The method according to claim 1, that comprises the further steps of: (xi) monitoring an operational water level in the wash tub while the circulation pump is running at a predetermined pump speed, (xii) detecting an operational level that is lower than a known required operational level that corresponds to said predetermined pump speed, (xiii) starting a dynamic refilling of the dishwasher by opening the water inlet, (xiv) stopping the dynamic refilling by closing the water inlet when said required operational water level is detected in the wash tub, wherein the operational water level is monitored and/or detected by the analogue pressure sensor.

5. The method according to claim 1, that comprises controlling an allowed maximum water level inside the wash tub and the subsequent steps of: (xv) recording the actual total open time of the water inlet during all water filling steps of the present program cycle, (xvi) calculating an allowed maximum total open time for the water inlet during a wash cycle basing on a known allowed maximum water volume inside the wash tub and on the flow rate of the inlet water determined during the static filling, and (xvii) calculating a remaining allowed maximum total open time for the water inlet.

6. The method according to claim 5 that comprises the further subsequent step of: (xviii) closing the water inlet when said allowed maximum total open time has been reached.

7. The method according to claim 5, comprising the further subsequent steps of: (xix) determining the actual water level in the wash tub, (xx) starting an at least partial drainage of the water comprised in the wash tub by opening a drain valve or switching on a drain pump of the dishwasher, (xxi) stopping the drainage when a predetermined drainage water level is detected in the wash tub, (xxii) calculating the volume of the drained water basing on the water levels before and after the drainage using an analogue pressure sensor, (xxiii) calculating a supplemental filling time corresponding to the volume of the drained water basing on the inlet water flow rate determined during the static filing, and (xxiv) increasing the allowed maximum total open time for the water inlet by said supplemental filling time.

8. The method according to claim 7 that comprises an additional subsequent step of: (xxv) adding a predetermined substitute volume of water by opening the water inlet for an open time that is calculated on the basis of said predetermined substitute volume water volume and on the inlet water flow rate determined during the static filling, wherein said predetermined substitute volume of water is not allowed to be larger than the difference between said allowed maximum water level inside the wash tub and said drainage water level.

9. The method according to claim 1, that comprises the subsequent steps of: (xxvi) recording the overall total open time of the water inlet during all water filling steps of the present program cycle and during all previous program cycles since a regeneration cycle of a softener unit of the dishwasher was last executed, (xxvii) calculating the total water volume that has been filled into the wash tub since the last generation cycle, basing on the flow rate of the inlet water determined during at least one static filling and on the recorded total open time of the water inlet since the last regeneration cycle, (xxviii) monitoring since the last regeneration cycle whether a predetermined regeneration-triggering volume of filling water has been filled into the wash tub using an analogue pressure sensor, (xxix) initiating a regeneration cycle of a softener unit of the dishwasher, after said regeneration-triggering volume of filling water has been reached.

10. The method according to claim 1, wherein an analogue pressure sensor is used for detecting an operational water level or a regeneration-triggering volume of filling water.

11. The method for filling a wash tub of a dishwasher with water, according to claim 1, comprising the subsequent steps of: (xxx) starting a program cycle of the dishwasher, (xxxi) determining at the start of the program cycle whether a water inlet of the dishwasher could be opened, and (xxxii) eventually indicating to a user of the dishwasher that the water inlet could not be opened, wherein said determination involves executing a water level measurement in the bottom region of a water-collecting sump pot of the dishwasher essentially at the time of starting the program cycle by measuring the water pressure using an analogue pressure sensor.

12. A computer program product stored on a non-transitory computer usable medium, comprising computer readable program means for causing an electronic control unit to perform the method according to claim 1.

13. Dishwasher comprising the at least one analogue pressure sensor, wherein the dishwasher is adapted to execute the method according to claim 1, wherein the dishwasher comprises an electronic control unit that is adapted to execute said method according to corresponding pressure signals provided by at least one analogue pressure sensor.

14. Dishwasher comprising the at least one analogue pressure sensor, wherein the dishwasher is adapted to execute said computer program product according to claim 12, wherein the dishwasher comprises the electronic control unit that is adapted to execute said computer program product according to corresponding pressure signals provided by the at least one analogue pressure sensor.

15. The method according to claim 1 further comprising draining the wash tub during a drain step, wherein the drain step further comprises calibrating the analogue pressure sensor while a drain pump is operating at an end of the drain step.

16. The method according to claim 1 further comprising pulsing the circulation pump when the further pump speed is operating.

17. The method according to claim 1, wherein the static filling step defines a first switch back point comprising a first value of the analogue pressure sensor and the dynamic filling step defines a second switch back point comprising a second value of the analogue pressure sensor, wherein the first switch back point is different than the second switch back point.

18. A method for filling a wash tub of a dishwasher with water, wherein the wash tub comprises a water-collecting sump pot that is fixed to an opening in its bottom and said method forms part of a program cycle for the operation of the dishwasher, said method comprising a step of: (i) opening a water inlet of the dishwasher and executing a static filling of the wash tub wherein a circulation pump of the dishwasher is kept deactivated, (ii) detecting a predetermined lower water level inside the sump pot, (iii) starting to measure the time for the static filling when said lower water level is detected, (iv) detecting a predetermined upper water level inside the sump pot and stopping the static filling, (v) determining a flow rate of the inlet water during the static filling basing on the duration of the static filling and on a known sump pot volume comprised between said upper water level and said lower water level of the sump pot, (vi) executing a percentaged filling of the wash tub after the upper water level of the static filling has been reached, wherein the circulation pump is kept deactivated and a predetermined percentaged water volume is added to the wash tub by opening the water inlet for an open time corresponding to said percentaged water volume, wherein said open time is calculated based on said percentaged water volume and on the inlet water flow rate determined during the static filling, (vii) switching on the circulation pump and keeping it running at a first pump speed, (viii) detecting an insufficient operational water level in the wash tub that is lower than a known first required operational water level that corresponds to full load operation of the circulation pump at said first pump speed, (ix) executing a dynamic filling of the wash tub while the circulation pump is running by opening the water inlet until said first required operational water level is detected inside the wash tub, wherein both the insufficient operational water level and the first required operational water level are detected by an analogue pressure sensor, and (x) draining the wash tub during a drain step, wherein the drain step further comprises calibrating the analogue pressure sensor while a drain pump is operating at an end of the drain step.

Description

(1) The present invention will be described in further detail by example of a preferred embodiment with reference to the accompanied drawings, in which

(2) FIG. 1 illustrates a schematic side view of a dishwasher according to a preferred embodiment of the present invention, and

(3) FIG. 2 is an enlarged sectional view of FIG. 1 with some added detail.

(4) As shown in FIG. 1 the dishwasher 10 comprises a wash tub 12 for taking up wash load (not shown) that is delimited by a back wall (to the left), two opposing side walls (not shown), a top wall (at the top), a bottom at its lower end that has an opening that is fixed to a water-collecting sump pot 16, a frontal opening (to the right, not indicated) that in FIG. 1 is closed by the frontal loading door 14. At least one dishwasher sprayer 18 is arranged inside the wash tub 12 for spraying pressurized washing water onto the wash load. The dishwasher sprayer receives pressurized washing water from a circulation pump (not shown) of the dishwasher, wherein the circulation pump during operation sucks water from a corresponding opening (not shown) in the sump pot.

(5) An analogue pressure sensor 20 is arranged besides the sump pot 16 and hydraulically connected to the sump pot by a connection pipe. The sump pot comprises an air trap 21 that shields the inlet of the connection pipe of the analogue pressure sensor from direct contact with the wash water.

(6) As can be seen better in FIG. 2, the air trap has a lower free edge that is arranged at a relatively small distance from the bottom of the sump pot as compared to the overall height of the sump pot up to at least the predetermined upper water level. However, as can also be seen in FIG. 2 said distance is preferably large enough that a level of residual water 29 that remains inside the bottom region of the sump pot after a correctly executed final drainage step of a wash cycle does not reach the free lower edge of the air trap.

(7) The predetermined lower water level 22 in the sump pot that is the starting level of the static filling is arranged somewhat above the lower edge of the air trap 21. Consequently, the predetermined lower water level 22, that is detected as a starting signal of the static filling step of the method of the invention of filling the wash (12) with water, gives a clearly different pressure signal of the analogue pressure sensor 20 as compared to an empty sump or to any level of residual water 29 that remains inside the bottom region of the sump pot after a correct final drainage step.

(8) Within the sump pot 16 and within the lower portion of the wash tub 12, five different water levels 22, 24, 28, and 26 and 28, as well as an additional hypothetical water level 27, that however would only occur if the circulation pump were stopped when running under full-load conditions, are indicated.

(9) The already mentioned predetermined lower water level 22 inside the sump pot 16 is the lowest level detected within the dishwasher 10 according to the invention. As already mentioned, the predetermined lower water level 22 is defined marginally above the bottom of the sump pot 16.

(10) The predetermined upper water level 24 or static fill/water level 24 is depicted above the predetermined lower water level 22. The predetermined upper water level 24 is however preferably still within the lower region of the sump pot that has a favourable, relatively small cross section as compared to the bottom region of the wash chamber which is arranged on top of the sump pot that allows to determine with high accuracy the change of the volume between at least said predetermined lower water level and said predetermined upper water level 24 of the static filling step of the invention, as has been described herein above.

(11) As also shown in the figures, the lower portion of the sump pot 16, which includes the predetermined lower water level 22 and the predetermined upper or static fill level 24, has a relative small cross-section. Thus, a change of the level in said lower portion of the sump pot 16 corresponds with a relative small change of the volume. In the example shown, the lower portion of the sump pot 16 has a cylindrical shape.

(12) Since the detected pressure of the analogue pressure sensor 20 corresponds with the level, the change of the volume may be determined exactly. In a higher portion of the sump pot 16 and/or in the bottom region of the wash tub 12 that comprises an opening (not shown) to which the sump pot 16 is fixed the cross-section becomes wider. The volume between the predetermined lower water level 22 and the predetermined upper or static fill level 24 is predetermined and therefore well known. For example, the volume can be one liter.

(13) In a lower portion of the wash tub 12 are in addition indicated: a percentaged fill level 26 corresponding to the total water level in the wash tub after both steps of static filling and of percentaged filling of the invention; a required operational water level 28 that corresponds to the minimum water level required in the wash tub 12 during operation of the circulation pump under full-load conditions at a predetermined pump speed; an insufficient operational level 28 that corresponds to an insufficient water volume in the wash tub 12 that does not allow a full-load operation of the circulation pump at a predetermined pump speed.

(14) During the filling method of the invention, at first the water inlet 13 is opened and the sump pot 16 is filled with a small volume of water up to the predetermined lower water level 22 while the circulation pump is kept switched off. The precise volume of that filled water varies to an unknown extent, because it is not known whether the sump pot 16 is completely empty or whether a small amount of residual water 29 from the previous program cycle is still in the bottom region of the sump pot 16.

(15) Subsequently, the lower predetermined water level 22 of the above-mentioned static filling is reached at the time point T1 and detected by the analogue pressure sensor as the pressure P1, and the measurement of the time for the static filling is started and the static filling begins by opening the water inlet 13, and wherein the circulation pump is still kept inactivated. When subsequently the predetermined upper or static fill level 24 is reached at the time point T2 and detected by the analogue pressure sensor as the pressure P2, wherein the circulation pump is still kept switched off, the static filling is stopped. Subsequently, the flow rate of the inlet water entering through the water inlet 13 is calculated basing on the duration of the time span between T1 and T2 and on the known sump pot volume 17 between the lower predetermined water level 22 and the predetermined upper or static fill level 24, which in the present example is one liter.

(16) Subsequently, the percentaged filling step of the filling method of the invention is executed, wherein the predetermined percentaged water volume 19 is filled into the wash tub 12 by opening the water inlet 13 for a time corresponding to the predetermined percentaged water volume 1 and calculated basing on the flow rate of the inlet water calculated in the static filling step. After executing the percentaged filling step and while the circulation pump is still kept switched off, the wash tub 12 that communicates with the sump pot 16 has been filled up with water to the percentaged fill level 26, comprising a water volume that consists essentially of the sump pot volume 17 and the percentaged water volume 19.

(17) The volume of water corresponding to the percentaged fill level 26 while the circulation pump is still switched off is almost sufficient or under ideal conditions is already sufficient for the operation of the circulation pump at a first, predetermined pump speed.

(18) However, in most cases the dynamic water level within the wash tub 12 will subsequently drop from the percentaged fill level 26 to the insufficient operational level 28 when the circulation pump is switched on at a predetermined first pump speed and the wash water is sprayed through the at least one dish washer sprayer 18 and the entire wash tub 12 and the wash load therein is wettened. This effect is itself known in the prior art, wherein the magnitude of the dynamic water level drop is essentially proportional to the pump speed.

(19) Subsequently, after switching on the circulation pump, the dynamic filling step of the filling method of the invention is executed by opening the water inlet 13 in order to fill up from the insufficient operational water level 28 to a known required operational water level 28 that is sufficient for full load operation of the circulation pump at the predetermined first pump speed. During the dynamic filling the circulation pump is being operated at said first predetermined pump speed. The dynamic filling step is again controlled using the analogue pressure sensor and the known operational water level 28 that corresponds to the full load operation of the circulation pump at the predetermined first pump speed.

(20) The operational water level 28 is indicated in the figures above the insufficient operational water level 28. Both refer to the dynamic conditions of operating of the circulation pump at the predetermined first pump speed. In contrast, the percentaged fill level 26 refers to the still switched off circulation pump. In the figures, the percentaged fill level 26 is indicated above both, the required operational water level 28 and the insufficient operational water level 28. However, whereas the insufficient operational water level 28 necessarily is below the percentaged fill level 26 because of the dynamic water level drop upon switching on the circulation pump as described above, the operational water level 28 is not necessarily below the percentaged fill level 26 and the figures just show one possible situation.

(21) In the figures the hypothetical water level 27 is in addition indicated, that however would only occur if the circulation pump were stopped while running under full-load conditions at said first predetermined pump speed. In the example shown, the hypothetical water level 27 shall correspond schematically to the required operational water level 28 that refers however to the dynamic conditions of the operating circulation pump. The hypothetical water level 27 is only indicated to illustrate schematically the rise in the water level as compared to the percentaged fill level 26 (that refers to the still switched-off circulation pump) that occurs during the dynamic filling.

(22) Though the figures refer in an explicit way to an example of the filling routine according to the first aspect of the invention they can be used by analogy also for the illustration of the second to sixth aspects of the invention.

(23) In particular, the figures can be used by analogy also for the illustration of the second aspect of the invention that refers to the use of the above-described novel filling routine in order to avoid an undesirable overflow of the water that is being filled into the wash tub 12. In particular the lower edge of the door opening is clearly shown in the figures. In addition, it is also readily understandable from the figures how the invention allows to design the bottom of the wash tub more flat as in the prior art and consequently to increase the capacity of the wash tub 12.

(24) The figures can be used by analogy also for the illustration of the fourth aspect of the invention that refers to indicating whether the water inlet 13 is closed. In this regard FIG. 2 comprises a suitable schematic illustration of the relative orientation of the bottom of the sump pot 16, a residual water level 29 from a previous program cycle, the lower free edge of the air trap 21 and the predetermined lower water level 22 which corresponds to the lowest water level in the sump pot that is measured by the analogue pressure sensor 20 almost immediately after the start of the program cycle.

(25) Although illustrative embodiments of the present invention have been described herein with reference to the accompanying drawings, it is to be understood that the present invention is not limited to those precise embodiments, and that various other changes and modifications may be affected therein by one skilled in the art without departing from the scope or spirit of the invention. All such changes and modifications are intended to be included within the scope of the invention as defined by the appended claims.

LIST OF REFERENCE NUMERALS

(26) 10 dish washer 12 wash tub 13 water inlet 14 dish washer door 16 dish washer sump pot 17 sump pot volume 18 dish washer sprayer 19 percentaged water volume 20 analogue pressure sensor 21 air trap 22 lower water level 24 upper water level 26 percentaged fill level 27 hypothetical operational level (if circulation pump were stopped) 28 required operational level 28 insufficient operational level 29 residual water from a previous program cycle