WO2016096020A1

WO2016096020A1 - Dishwasher comprising a spray arm arrangement

Info

Publication number: WO2016096020A1
Application number: PCT/EP2014/078530
Authority: WO
Inventors: Per-Erik Pers; Elianne Lindmark
Original assignee: Electrolux Appliances Aktiebolag
Priority date: 2014-12-18
Filing date: 2014-12-18
Publication date: 2016-06-23

Abstract

A dishwasher (1) comprising a spray arm arrangement (2) and a washing chamber (3). The spray arm arrangement (2) comprises a spray arm (4) arranged to rotate around a first axis of rotation (5) within said washing chamber (3). The spray arm (4) is provided with one or more spray nozzles (6) arranged to spray washing liquid into said washing chamber (3). The dishwasher (1) further comprises an optical sensor (7), for detecting an angular position of said spray arm (4), which optical sensor (7) comprises a transmitter (8) for transmitting a light beam and a receiver (9) for detecting said light beam. The spray arm arrangement (2) further comprises a light beam interrupting device (10) arranged to rotate with said spray arm (4), which light beam interrupting device (10) comprises at least a first tooth (11 a) arranged to cyclically interrupt said light beam during rotation of said spray arm (4).

Description

DISHWASHER COMPRISING A SPRAY ARM ARRANGEMENT

TECHNICAL FIELD

The present invention relates to a dishwasher comprising a spray arm arrangement.

BACKGROUND

Today's dishwashers are expected to perform high quality wash of items. Further, environmental concerns require an efficient use of water and energy during a wash cycle. The requirement of performing high quality wash of items and the requirement of efficient use of water and energy during a wash cycle puts requirements on spray arm arrangements for dishwashers. Usually, a spray arm comprising spray nozzles is rotatably arranged inside a washing chamber of a dishwasher to distribute a washing liquid, such as water and detergent, on to items in the dishwasher. The spray arm may be driven to rotate by the force of cleaning sprays from the spray nozzles. The spray arm may also comprise a dedicated drive nozzle adapted to create a driving force on the spray arm. During rotation of the spray arm within the washing chamber, the water and detergent is distributed on to the items with a pressure adapted not to harm glass or other delicate items. However, a limitation in spray pressure may lead to heavily soiled items like pots and pans not being properly cleaned. These items may thus require a second washing procedure to be sufficiently cleaned, leading to unnecessary waste of water. Further, items located in the dishwasher, such as cutlery, may block the rotation of the spray arm. A blocked spray arm will only distribute washing liquid over a limited region of the dishwasher, thereby wasting water and energy without performing washing action as intended.

Document DE 4020898 A1 describes a method of detecting a blocked spray arm using a rotation detecting sensor. The sensor provides a pulse signal every time the spray arm passes the sensor, which pulse signal restarts a countdown. If the spray arm is blocked the sensor will not provide the pulse signal and the countdown will not be restarted. When the countdown ends, the washing procedure will be ended. In one embodiment, the sensor is an optical sensor which provides the pulse signal when a tip of the spray arm interrupts a light beam. The method described in document DE 4020898 A1 is dependent on detection of the tip of the spray arm within the washing chamber.

Problems may arise with such detection since the environment within a wash chamber during a wash session is challenging, for example since the wash arm is spraying washing liquid having a high temperature into the washing chamber during rotation of the spray arm. Thereby, the method described in the document DE 4020898 A1 may result in an inexact detection of a blocked spray arm.

In view of the above, there is room for improvement of dishwashers comprising a spray arm arrangement.

SUMMARY

An object of the present invention is to provide a dishwasher with an improved spray arm arrangement.

According to an aspect of the invention, the object is achieved by a dishwasher comprising a spray arm arrangement and a washing chamber, the spray arm

arrangement comprising:

a spray arm arranged to rotate around a first axis of rotation within the washing chamber, the spray arm being provided with at least one spray nozzle arranged to spray washing liquid into the washing chamber, and

an optical sensor, for detecting an angular position of the spray arm, the optical sensor comprising a transmitter for transmitting a light beam and a receiver for detecting the light beam,

and wherein the spray arm arrangement further comprises a light beam interrupting device arranged to rotate with the spray arm, and wherein the light beam interrupting device comprises at least a first tooth arranged to cyclically interrupt the light beam during rotation of the spray arm.

Since the light beam interrupting device comprises at least a first tooth arranged to cyclically interrupt the light beam during rotation of the spray arm, a predictable detection of the angular position of the spray arm can be performed using the optical sensor. The tooth may comprise a protrusion or an elongated member extending from the light beam interrupting device with an axial and/or radial main extension with regard to the axis of rotation of the light beam interrupting device. Also, due to these features the optical sensor does not have to be placed in connection to the spray arm. Instead, the sensor may be spaced away from the spray arm to a location where it is less exposed to the spray from the nozzles. Thereby, a more robust arrangement is provided.

Furthermore, since the angular position of the spray arm can be detected when the at least first tooth of the light beam interrupting device passes the sensor, the rotational speed of the spray arm may be calculated using the time it takes for the spray arm to move between two known angular positions of the spray arm. Knowing the rotational speed of the spray arm, a current rotational position of the spray arm may be estimated based on the last known position and the rotational speed. The estimated current position of the spray arm may be used to adapt the cleaning intensity to different conditions in different areas of the washing chamber. The cleaning intensity may be adapted by changing the pressure of the cleaning sprays in different areas of the washing chamber, such as increasing the pressure in areas were heavily soiled items are placed and reducing the pressure in areas were glass and delicate items are placed.

Due to these features, an improved dishwasher is provided. As a result, the above mentioned object is achieved.

According to some embodiments, the light beam interrupting device further comprises at least a second tooth, wherein the at least a second tooth is arranged to interrupt the light beam at an angular position of the spray arm different from an angular position of the spray arm in which the at least a first tooth is arranged to interrupt the light beam.

Thereby, a more precise determination of the position of the spray arm can be achieved since also the at least a second tooth will interrupt the light beam. Hence, a more precise control of the pressure of the cleaning sprays can be achieved. The precision of the detection of the angular position may further be increased by providing a light beam interrupting device comprising three or more teeth each being arranged to cyclically interrupt the light beam during rotation of the spray arm.

According to some embodiments herein, a width of the at least first tooth is different from a width of the at least second tooth, such that the at least first tooth is arranged to interrupt the light beam for a different amount of time than the at least second tooth. Thereby, a specific length of the period in which the light beam is interrupted will correspond to a specific position of the spray arm. Thereby, the precision of the detection of the angular position may further be increased. Also, due to these features, a rotational direction of the spray arm may be detected.

According to some embodiments herein, the at least first tooth extends radially from the light beam interrupting device with regard to an axis of rotation of the light beam interrupting device. A radially extending tooth allows the light beam interrupting device to be compact in an axial direction, which may reduce required clearance for mounting the light beam interrupting device in the dishwasher.

According to some embodiments herein, the at least first tooth extends axially from the light beam interrupting device with regard to an axis of rotation of the light beam interrupting device.

According to some embodiments herein, the light beam interrupting device is arranged on the spray arm, such that an axis of rotation of the light beam interrupting device coincides with the first axis of rotation. By arranging the light beam interrupting device on the spray arm, a compact spray arm arrangement is provided.

According to some embodiments herein, the rotation of the spray arm is arranged to be driven by a force of the spray of washing liquid from the spray nozzle. Thereby, a cost efficient and reliable spray arm arrangement is achieved, since the number of moving parts in the arrangement can be kept at a minimum level.

According to some embodiments herein, the dishwasher further comprises a motor arranged to rotate the spray arm. Since a motor is arranged to rotate the spray arm instead of, or in addition to, the force of the spray nozzles, a larger proportion of the force of the sprays can be used for cleaning purposes. Furthermore, since the positioning of the spray arm and the cleaning force of the spray nozzles are separated from each other the cleaning force may be adapted independently from the position of the spray arm. Thereby, an even further improved dishwasher is provided. Further features of, and advantages with, the present invention will become apparent when studying the appended claims and the following detailed description. Those skilled in the art will realize that the different features described may be combined to create embodiments other than those described in the following, without departing from the scope of the present invention, as defined by the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The various aspects of the invention, including its particular features and advantages, will be readily understood from the following detailed description and the accompanying drawings, in which;

Fig. 1 illustrates a dishwasher with a wash arm arrangement according to some embodiments; Fig. 2 shows a light beam interrupting device according to some embodiments illustrated in a plane perpendicular to the axis of rotation of the light beam interrupting device;

Fig. 3a shows a light beam interrupting device according to some embodiments illustrated in a plane essentially parallel to the axis of rotation of the light beam interrupting device; and

Fig. 3b shows a light beam interrupting device according to some embodiments illustrated in a plane perpendicular to the axis of rotation of the light beam interrupting device.

DETAILED DESCRIPTION

The embodiments herein will now be described more fully with reference to the accompanying drawings. Like numbers refer to like elements throughout. Fig. 1 illustrates a dishwasher 1 according to some embodiments. The dishwasher 1 comprises a spray arm arrangement 2 and a washing chamber 3 for receiving items to be washed. The spray arm arrangement 2 is arranged inside the washing chamber 3 and comprises a spray arm 4 arranged to rotate around a first axis of rotation 5. The spray arm 4 may be provided with one or more spray nozzles 6. The spray arm 4 may comprise a hollow body connected to a washing liquid supply, such as a washing liquid pump 12. The hollow body of the spray arm 4 may further be in communication with the one or more spray nozzles 6 of the spray arm 4. Thereby, washing liquid may be pumped from the washing liquid supply into the spray arm 4 and out into the washing chamber 3 of the dishwasher via the one or more spray nozzles 6. The spray arm 4 may in some embodiments comprise one or more spray nozzles 6 being inclined in the sense that washing liquid being evacuated through the spray nozzle is evacuated in a direction opposite to an intended direction of rotation of the spray arm 4. Thereby, washing liquid evacuated via the spray nozzles 6 will create a reaction force applying a torque onto the spray arm 4 which may cause the spray arm 4 to rotate around the first axis of rotation 5. The spray arm arrangement 2 further comprises an optical sensor 7. The optical sensor 7 comprises a transmitter 8 for transmitting a light beam and a receiver 9 for detecting the light beam. The optical sensor 7 may be non-rotatably arranged to the dishwasher 1 . The spray arm arrangement 2 further comprises a light beam interrupting device 10 arranged to rotate with the spray arm 4, which light beam interrupting device 10 comprises an at least first tooth 1 1 a arranged to cyclically interrupt the light beam during rotation of the spray arm 4. The at least first tooth 1 1 a may comprise a protrusion or an elongated member extending from the light beam interrupting device 10 with an axial and/or radial main extension with regard to the axis of rotation 13 of the light beam interrupting device 10. Since the at least first tooth 1 1 a cyclically interrupts the light beam of the optical sensor 7, a rotational position of the spray arm 4, predefined by the position of the at least first tooth 1 1 a, is detected during rotation of the spray arm 4. By detecting the rotation of the spray arm 4, a blockage of the spray arm 4 may be detected. The spray arm arrangement 2 may further comprise a control unit (not shown) adapted to calculate a rotational speed of the spray arm 4, based on the distance the tooth travels and the time it takes between two interruptions of the light beam. The control unit may further be adapted to determine the current rotational position of the spray arm 4 based on the known position of the at least first tooth 1 1 a and the calculated rotational speed. By determining the current rotational position of the spray arm 4, the cleaning intensity of the sprays may be adapted to different cleaning conditions in different areas of the washing chamber 3.

As illustrated in Fig. 1 the washing chamber 3 may comprise heavily soiled items, such as pots or pans, as well as delicate items, such as glasses. The control unit may further be adapted to increase the cleaning intensity of the sprays in parts of a swept area of the spray arm where the heavily soiled items are placed and to reduce the cleaning intensity in parts of the swept area where the delicate items are placed, based on the detected position of the spray arm. Thereby maximum cleaning power may be applied on the heavily soiled items while a reduced power is applied on the delicate items. As a result the duration of the washing cycle may be reduced, thereby saving water and energy, whilst increasing the cleaning efficiency of the washing cycle.

In further embodiments, since an angular position of the spray arm 4 is detected, the control unit may further be adapted to switch of the sprays from the spray nozzles 6 in parts of the swept area of the spray arm 4 where no items are placed. This will further reduce the water consumption during the washing cycle.

Since the spray arm arrangement 2 comprises the light beam interrupting device 10 arranged to rotate with the spray arm 4, the optical sensor does not have to be placed in connection to the spray arm 4. Instead, the sensor may be spaced away from the spray arm 4 to a location where it is less exposed to the spray from the nozzles. In

embodiments herein, the light beam interrupting device 10 is arranged outside the washing chamber 3. In such embodiments, the light beam interrupting device 10 may be fixedly attached to a shaft, which shaft may be fixedly attached to the spray arm 4 at the spray arms 4 axis of rotation 5, such that the light beam interrupting device 10 rotates with the spray arm 4.

According to some embodiments, the light beam interrupting device 10 may comprise at least a first tooth 1 1 a and at least a second tooth 1 1 b. The at least first tooth 1 1 a may be arranged to interrupt the light beam at an angular position of the spray arm 4 different from an angular position of the spray arm 4 in which the at least second tooth 1 1 b is arranged to interrupt the light beam. Thereby, a more precise determination of the position of the spray arm 4 may be achieved since also the at least a second tooth will interrupt the light beam interrupting device in a second rotational position. Hence, the control unit may be adapted to more precisely control the pressure of the cleaning sprays. The precision of the positioning may be further increased by increasing the number of teeth 1 1 on the light beam interrupting device 10. The first tooth 1 1 a may be arranged on the light beam interrupting device 10 at a different angular position than the at least second tooth 1 1 b, such that the first and second tooth are arranged at an angle to each other with regard to an axis of rotation 13 of the light beam interrupting device 10. In some embodiments herein, the angle between the first and the at least second tooth is more than 0° but less than 180°, such that a rotational distance, i.e. the distance around a circumference of the light beam interrupting device 10, between the first tooth 1 1 a and the second tooth 1 1 b is different than the rotational distance between the second tooth 1 1 b and the first tooth 1 1 a, during a complete rotation of the light beam interrupting device 10. According to some embodiments, the light beam interrupting device 10 comprises at least three teeth 1 1 a, 1 1 b and 1 c, each being arranged at an angle to each other with regard to the axis of rotation 13 of the light beam interrupting device 10. The at least three teeth 1 1 a, 1 1 b and 1 1 c may be arranged such that at least three of the angles between each tooth 1 1 a, 1 1 b and 1 1 c are different from each other. Thereby, the direction of rotation of the spray arm 4 may be determined since the sequence of angles, and thereby the sequence of rotational distances between the teeth 1 1 a, 1 1 b and 1 1 c, will be different when the spray arm 4 rotates in a clockwise direction compared to a counter clockwise direction. According to some further embodiments, a width of the first tooth 1 1 a is different from a width of the second tooth 1 1 b, such that the first tooth 1 1 a is arranged to interrupt the light beam for a different amount of time than the second tooth 1 1 b. Thereby, a specific length of the period the light beam is interrupted corresponds to a specific position of the spray arm, such that a specific signal pattern is created when the light beam interrupting device 10 rotates. Such signal pattern can be monitored by the control unit to determine a rotational direction of the spray arm 4. The direction of rotation of the spray arm 4 can be detected, since the signal pattern will differ depending on the direction of rotation. In some embodiments the teeth 1 1 are of the same width but are placed in groups, such that each group comprises a different number of teeth 1 1 , wherein the teeth 1 1 of each group are arranged at the same radius from the axis of rotation 13 of the activating device 10. For example, the second tooth 1 1 b may be replaced by a group of two teeth 1 1 and a third tooth 1 1 c may be replaced by a group of three teeth 1 1 . Each group of teeth 1 1 may be arranged at a longer rotational distance from each other than the teeth 1 1 in each individual group.

Fig. 2 illustrates a light beam interrupting device 10 according to some embodiments. The light beam interrupting device 10 comprises a first tooth 1 1 a, which extends radially from the light beam interrupting device 10 with regard to an axis of rotation 13 of the light beam interrupting device 10. The light beam interrupting device 10 is illustrated in a plane perpendicular to the axis of rotation 13 of the light beam interrupting device 10. The light beam interrupting device 10 comprises a circular body extending in a plane perpendicular to the axis of rotation 13. The first tooth 1 1 a is arranged at the

circumference of the circular body and extends in the same plane perpendicular to the axis of rotation 13 as the circular body itself. Since the first tooth 1 1 a extends in a radial direction to the axis of rotation 13, the light beam interrupting device 10 may be compact in an axial direction, thereby reducing the required clearance for mounting the light beam interrupting device 10 in the dishwasher 1 . In the embodiment shown, the light beam interrupting device 10 further comprises a second tooth 1 1 b and a third tooth 1 1 c, which teeth 1 1 b and 1 1 c are also arranged at the circumference of the circular body and extend radially from the light beam interrupting device 10 with regard to an axis of rotation 13 of the light beam interrupting device 10.

Fig. 3a and Fig. 3b illustrate an exemplary embodiment of the light beam interrupting device 10. Fig. 3a shows the light beam interrupting device 10 illustrated in a plane essentially parallel to the axis of rotation 13 of the light beam interrupting device 10 and Fig. 3b shows the light beam interrupting device illustrated in a plane perpendicular to the axis of rotation 13. In the illustrated embodiment, the first tooth 1 1 a extends axially from the light beam interrupting device 10 with regard to the axis of rotation 13 of the light beam interrupting device 10. The light beam interrupting device 10 comprises a partially circular body radially extending in a plane perpendicular to the axis of rotation 13 of the light beam interrupting device 10, with the first tooth 1 1 a being arranged at the circumference of the body at a radius from the rotational axis of the body. The body of the light beam interrupting device 10 may however also be a circular body. The first tooth 1 1 a is arranged at the circumference of the partially circular body and extends in a plane perpendicular to the partially circular body, such that the at least first tooth and the circular body have an L-shaped cross section. The light beam interrupting device 10 further comprises a second tooth 1 1 b and a third tooth 1 1 c, which teeth 1 1 b and 1 1 c also are arranged at the circumference of the partially circular body and extend axially from the partially circular body with regard to the axis of rotation 13 of the light beam interrupting device 10. In the illustrated embodiment the first tooth 1 1 a has a different width than the at least second tooth 1 1 b and the at least third tooth 1 1 c. The three teeth 1 1 a, 1 1 b and 1 1 c may further be arranged such that at least three of the rotational angles, and thereby the rotational distances, between the teeth 1 1 a, 1 1 b and 1 1 c are different from each other. In some embodiments, the light beam interrupting device 10 is arranged on the spray arm 4, such that an axis of rotation 13 of the light beam interrupting device 10 coincides with the first axis of rotation 5.

In some embodiments, the dishwasher 1 further comprises a motor, preferably an electric motor 14, arranged to rotate the spray arm 4. Since the rotation of the spray arm 4 is driven by the motor instead of, or in addition to, the sprays from the spray nozzles 6, a larger proportion of the force of the sprays can be used for cleaning purposes.

Furthermore, since the positioning of the spray arm 4 and the cleaning force of the sprays from the spray nozzles 6 are separated from each other, the cleaning force may be adapted independently from the position of the spray arm 4. For example, the control unit may be adapted to reduce the rotational velocity and/or increase the spray pressure when the spray arm 4 passes areas of the dishwasher 1 comprising heavily soiled items. The control unit may further be adapted to increase the rotational velocity and/or reduce the spray pressure, when the spray arm 4 passes areas comprising delicate items. Thereby, a spray arm arrangement 2 is provided which further improves the cleaning performance of the dishwasher 1 .

The dishwasher 1 provided may comprise two or more spray arm arrangements 2, as illustrated in Fig. 1 . It is to be understood that the foregoing is illustrative of various examples and the present disclosure is not to be limited to the specific varieties disclosed and that modifications to the disclosed examples, combinations of features of disclosed examples as well as other varieties are intended to be included within the scope of the appended claims.

Claims

1 . A dishwasher (1 ) comprising a spray arm arrangement (2) and a washing chamber (3), said spray arm arrangement (2) comprising:

- a spray arm (4) arranged to rotate around a first axis of rotation (5) within said washing chamber (3), said spray arm (4) being provided with one or more spray nozzles (6) arranged to spray washing liquid into said washing chamber (3), and

- an optical sensor (7), for detecting an angular position of said spray arm (4), said optical sensor (7) comprising a transmitter (8) for transmitting a light beam and a receiver (9) for detecting said light beam,

characterized in that said spray arm arrangement (2) further comprises a light beam interrupting device (10) arranged to rotate with said spray arm (4), and wherein said light beam interrupting device (10) comprises at least a first tooth (1 1 a) arranged to cyclically interrupt said light beam during rotation of said spray arm (4).

2. The dishwasher (1 ) according to claim 1 , wherein said light beam interrupting device (10) further comprises at least a second tooth (1 1 b), wherein said at least second tooth (1 1 b) is arranged to interrupt said light beam at an angular position of said spray arm (4) different from an angular position of said spray arm (4) in which said at least first tooth (1 1 a) is arranged to interrupt said light beam.

3. The dishwasher (1 ) according to claim 2, wherein a width of said at least first tooth (1 1 a) is different from a width of said at least second tooth (1 1 b), such that said at least first tooth (1 1 a) is arranged to interrupt said light beam for a different amount of time than said at least second tooth (1 1 b).

4. The dishwasher (1 ) according to any one of the preceding claims, wherein said at least first tooth (1 1 a) extends radially from said light beam interrupting device (10) with regard to an axis of rotation (13) of said light beam interrupting device (10).

5. The dishwasher (1 ) according to any one of the preceding claims, wherein said at least first tooth (1 1 a) extends axially from said light beam interrupting device (10) with regard to an axis of rotation (13) of said light beam interrupting device (10).

6. The dishwasher (1 ) according to any one of the preceding claims, wherein said light beam interrupting device (10) is arranged on said spray arm (4), such that an axis of rotation (13) of said light beam interrupting device (10) coincides with said first axis of rotation (5).

7. The dishwasher (1 ) according to any one of the preceding claims, wherein said rotation of said spray arm (4) is arranged to be driven by the force of the spray of washing liquid from said spray nozzle (6).

8. The dishwasher (1 ) according to any one of the preceding claims, further comprising a motor (14) arranged to rotate said spray arm (4).