EP2721989A1

EP2721989A1 - Dishwasher

Info

Publication number: EP2721989A1
Application number: EP13185942.3A
Authority: EP
Inventors: Kazunari Shimomura; Naoki Hiromatsu
Original assignee: Panasonic Corp
Current assignee: Panasonic Corp
Priority date: 2012-10-18
Filing date: 2013-09-25
Publication date: 2014-04-23
Also published as: TW201416047A; JP2014079489A; CN103767654A

Abstract

A dishwasher of the present invention includes washing tub (2), washing pump (5), and wash nozzle (15). Wash nozzle (15) is composed of first arm nozzle (6) and second arm nozzle (7). Second arm nozzle (7) has its rotation center at a position decentered from the rotation center of first arm nozzle (6), is provided on first arm nozzle (6) through hook-and-catch locking part (8), and has multiple washing water spray openings (11). Second arm nozzle (7) has at least one washing water spray outlet (12) directly above rotation shaft (7a), on top surface (7c) of second arm nozzle (7), thereby preventing hook-and-catch locking part (8) of second arm nozzle (7) from detaching due to a dynamic water pressure of washing water pressure-transferred.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a dishwasher for washing dishes by spraying washing water.

2. Background Art

Conventional dishwashers of this type wash dishes by spraying washing water through spray outlets of rotating arm nozzles. Concretely, a dishwasher is disclosed in Japanese Patent Unexamined Publication No. H05-168581 (hereinafter, described as patent literature 1) that efficiently washes tableware uniformly with first arm nozzle and second arm nozzle rotatable arm nozzles, where the second arm nozzle is provided on the first arm nozzle with the center of the second arm nozzle decentered from that of the first arm nozzle.
The following describes the conventional dishwasher described in patent literature 1 using FIG. 3. FIG. 3 is a sectional side view illustrating the internal structure of the dishwasher.
As shown in FIG. 3, the conventional dishwasher includes a wash nozzle composed of first arm nozzle 104 and second arm nozzle 105. First arm nozzle 104 communicates with discharge outlet 103 of washing pump 102 placed on the substantially central part of the bottom surface of washing tub 101, and is rotatably provided substantially horizontally. Second arm nozzle 105 is rotatably provided on first arm nozzle 104 with the center of second arm nozzle 105 decentered from rotation axis A of first arm nozzle 104 by a given distance.
First arm nozzle 104 and second arm nozzle 105 have first spray outlet 106 and second spray outlet 107, respectively, for spraying washing water. At least one of the members of first spray outlet 106 and second spray outlet 107 are provided so that washing water is sprayed diagonally upward. Resultingly, spray reactive forces of washing water sprayed diagonally upward makes first arm nozzle 104 and second arm nozzle 105 rotate in given directions.
In detail, the dishwasher structured as above first feeds a given amount of washing water into washing tub 101 and activates washing pump 102. The washing water fed is pressure-transferred to the inside of first arm nozzle 104 and second arm nozzle 105 by washing pump 102. The washing water pressure-transferred is sprayed through first spray outlet 106 of first arm nozzle 104 and through second spray outlet 107 of second arm nozzle 105. Resultingly, the washing water sprayed washes tableware while rotating first arm nozzle 104 and second arm nozzle 105. At this moment, second arm nozzle 105 rotates on its axis while revolving with rotation of first arm nozzle 104. Consequently, the revolution path of second spray outlet 107 moves uniformly. Concretely, the revolution path of second spray outlet 107 covers nearly all the range of the revolution. In other words, second spray outlet 107 moves throughout nearly all the range of the revolution during wash time and sprays washing water into the washing tub uniformly. This allows the dishwasher to efficiently wash tableware in washing tub 101 uniformly.
Typical second arm nozzles 105 of the dishwasher, however, is lighter than first arm nozzle 104. For this reason, at startup of washing pump 102, a dynamic water pressure of washing water pressure-transferred undesirably causes second arm nozzle 105 to detach from hook-and-catch locking part 108 (formed of fitting ratchet 108) of first arm nozzle 104.
To avoid the above-described problem, a measure is taken in which screws rather than fitting ratchet 108 are used for fitting, for instance. In this case, however, the sealing structure between arm nozzles needs to be redesigned simultaneously, the rotation sealing part for fitting ratchet 108 is changed to static pressure sealing, for instance. This design requires washers, for instance, to reduce slide resistance at the rotation sealing part. Further, this design decreases workability when a user removes second arm nozzle 105 from first arm nozzle 104, which results in poor maintainability of the dishwasher.
Meanwhile, to make second arm nozzle 105 be more resistant to detaching from hook-and-catch locking part 108 by a component structure and a balanced sealing structure (easily detachable), the strength of fitting ratchet 108 may be increased. In this case, however, the maintainability decreases in the same way as above. Further, when second arm nozzle 105 is repeatedly detached and attached for maintenance, the ratchet part of fitting ratchet 108 undesirably breaks easily, for instance.

SUMMARY OF THE INVENTION

To solve the above-described problems, a dishwasher of the present invention includes a washing tub for containing objects to be washed; a washing pump for pressure-circulating washing water in the washing tub; and a wash nozzle communicating with the washing pump for washing objects to be washed by spraying washing water. The wash nozzle is composed of rotatable first and second arm nozzles. The second arm nozzle has its rotation center at a position decentered from that of the first; is provided on the first through a hook-and-catch locking part; and has multiple washing water spray openings. The second arm nozzle is provided with at least one washing water spray opening directly above the rotation shaft (the vertical water path linking with the first arm nozzle), on the top surface of the second arm nozzle. This prevents the ratchet fitting part of the second arm nozzle from detaching due to a dynamic water pressure at startup of the washing pump. This results in a dishwasher with a small number of parts and high maintenance workability.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a sectional side view illustrating the internal structure of a dishwasher according to an exemplary embodiment of the present invention.
FIG. 2A is an enlarged sectional view of the substantial part illustrating the structure of the second arm nozzle of a conventional dishwasher.
FIG. 2B is an enlarged sectional view of the substantial part illustrating the structure of the second arm nozzle of the dishwasher according to the exemplary embodiment.
FIG. 3 is a sectional side view illustrating the internal structure of the conventional dishwasher.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, a description is made of an exemplary embodiment of the present invention with reference to the related drawings. The scope of the present invention is not limited by the exemplary embodiment.

EXEMPLARY EMBODIMENT

Hereinafter, a description is made of the structure of a dishwasher according to an exemplary embodiment of the present invention.
FIG. 1 is a sectional side view illustrating the internal structure of the dishwasher according to an exemplary embodiment of the present invention.
As shown in FIG. 1, the dishwasher of this embodiment is composed of at least the following components inside body 1: washing tub 2, dish basket 4, washing pump 5, and wash nozzle 15. Washing tub 2 is provided therein with dish basket 4 on which wash objects 3 (objects to be washed) (e.g. tableware) are placed. Washing pump 5, attached to the bottom of washing tub 2, pressure-transfers washing water to wash nozzle 15.
Wash nozzle 15 is composed of first arm nozzle 6 and second arm nozzle 7. First arm nozzle 6 communicates with discharge outlet 5a of washing pump 5, and is provided substantially or completely in the horizontal direction, rotatably around rotation center C1 shown in FIG. 1. Second arm nozzle 7 is provided on top surface 6a of first arm nozzle 6, rotatably around rotation center C2 at a position decentered from rotation center C1 of first arm nozzle 6. Further, second arm nozzle 7 is detachably attached to first arm nozzle 6 through hook-and-catch locking part 8 (formed of a fitting ratchet 8). In this case, rotation shaft 7a (corresponding to rotation center C2 of second arm nozzle 7) forms vertical water path 7b communicating with first arm nozzle 6.
The connection part connecting first arm nozzle 6 and second arm nozzle 7 through fitting ratchet 8 functions as rotation sealing part 9 at the bottom end of rotation shaft 7a. This seals the connection part between first arm nozzle 6 and second arm nozzle 7, thereby preventing washing water pressure-transferred to second arm nozzle 7 through first arm nozzle 6 from leaking out of the connection part.
Top surface 6a of first arm nozzle 6 is provided thereon with first spray outlet 10 for spraying washing water pressure-transferred from washing pump 5. Similarly, top surface 7c of second arm nozzle 7 is provided thereon with second spray outlet 11 (including a plurality of washing water spray openings) for spraying washing water pressure-transferred from washing pump 5 through vertical water path 7b. In this case, at least one of the members of first spray outlets 10 and second spray outlet 11 are formed so that washing water is sprayed diagonally upward. Consequently, spray reactive forces of washing water allow first arm nozzles 6 and second arm nozzle 7 to be rotated in desired directions.
Near the central part of top surface 7c of second arm nozzle 7, central spray outlet 12 (washing water spray opening), one of the members of second spray outlet 11 (including a plurality of water spray openings), is provided directly above rotation shaft 7a of second arm nozzle 7. In this case, the other members of second spray opening 11 (excluding central spray outlet 12) are arranged at positions other than directly above rotation shaft 7a, on top surface 7c of second arm nozzle 7, point-symmetrically with respect to rotation center C2 of second arm nozzle 7.
The dishwasher of this exemplary embodiment is structured as described above.
Hereinafter, a description is made of the operation and actions of the dishwasher according to the exemplary embodiment.
First, a user sets wash object 3 (object to be washed 3) onto dish basket 4; puts dish basket 4 into washing tub 2; and then starts operation of the dishwasher. Resultingly, a given amount of washing water is fed into washing tub 2 according to a given sequence.
Next, the user activates washing pump 5. Resultingly, washing water pressurized by washing pump 5 is pressure-transferred to first arm nozzle 6 rotatably provided and is sprayed through first spray outlet 10. Simultaneously, the washing water is fed from first arm nozzle 6 to second arm nozzle 7 through vertical water path 7b. Then, the washing water is sprayed upward toward wash object 3 through second spray outlet 11 (including a plurality of washing water spray openings 11) and through central spray outlet 12. At this moment, first arm nozzle 6 and second arm nozzle 7 spray washing water while rotating in desired directions due to spray reactive forces of the washing water sprayed through at least one of the members of first spray outlet 10 and second spray outlet 11.
Hereinafter, a description is made of the operation and actions of second arm nozzle 7 of the dishwasher according to the exemplary embodiment using FIGs. 2A and 2B.
FIG. 2A is an enlarged sectional view of the substantial part illustrating the structure of the second arm nozzle of a conventional dishwasher. FIG. 2B is an enlarged sectional view of the substantial part illustrating the structure of the second arm nozzle of the dishwasher according to the exemplary embodiment.
First, a description is made of the structure of the second arm nozzle of the conventional dishwasher using FIG. 2A. The conventional second arm nozzle is the case where a central spray opening, one of the washing water spray openings of this exemplary embodiment, is not provided on the top surface of the second arm nozzle.
As shown in FIG. 2A, conventional second arm nozzle 105 is designed so that the following two forces act in stable operation. The first force acts on second arm nozzle 105 vertically upward due to a dynamic water pressure of washing water pressure-transferred from first arm nozzle 104 through vertical water path 105a. The second force acts vertically downward due to a spray reactive force of washing water sprayed from second spray outlet 107, the self weight of second arm nozzle 105, and the weight of washing water filled inside second arm nozzle 105. Conventional second arm nozzle 105 is designed so that the second force is larger than the first force. Resultingly, second arm nozzle 105 does not rise but rotates with rotation sealing part 109 always undergoing a bearing stress in stable operation.
Meanwhile, from when washing pump 102 is in a stopped state to when washing pump 102 is in a state immediately after start up, the first force, a vertically upward force caused by washing water pressure-transferred from first arm nozzle 104 through vertical water path 105a, acts on second arm nozzle 105. The washing water, however, is not spraying through second spray outlet 107, and thus the second force (including a spray reactive force) does not act on second arm nozzle 105. Accordingly, second arm nozzle 105 is more likely to rise at startup than in stable operation.
In this case, second arm nozzle 105 is usually engaged to first arm nozzle 104 with fitting ratchet 108. Accordingly, second arm nozzle 105 rises to some extent, but fitting ratchet 108 does not detach. First arm nozzle 104 and second arm nozzle 105, however, are typically made of resin. Consequently, when washing water is heated for washing, the rigidity of fitting ratchet 108 deteriorates due to a contact with heated washing water, and the discharge pressure of washing pump 102 fluctuates, which can cause fitting by fitting ratchet 108 to detach. To prevent such a case, the rigidity of fitting ratchet 108 needs to be increased so that fitting does not detach easily. Increasing the rigidity, however, proportionately decreases the workability of detaching for maintenance. Further, when fitting ratchet 108 is repeatedly detached and attached, its ratchet part is more likely to break.
Hence, as shown in FIG. 2B, second arm nozzle 7 of the dishwasher of this exemplary embodiment is provided with central spray outlet 12, which one of a plurality of washing water spray openings directly above rotation shaft 7a near the central part of top surface 7c. Resultingly, at startup of washing pump 5, washing water is sprayed through central spray outlet 12 immediately after washing water has been pressure-transferred from first arm nozzle 6 through vertical water path 7b. This provides a downward spray reactive force, the second force described above, even at startup of washing pump 5.
That is to say, the embodiment is less likely to undergo a defect in which fitting ratchet 8 detaches due to a rise of second arm nozzle 7 than the case where central spray outlet 12 is not provided as in conventional second arm nozzle 105. This proportionately weakens a fitting force of fitting ratchet 8, thereby improving maintainability in detaching second arm nozzle 7, for instance.
As to central spray outlet 12 provided directly above rotation shaft 7a, no consideration is needed for the balance of downward moment caused by a spray reactive force with rotation center C2 of second arm nozzle 7 as a supporting point. This increases the degree of flexibility in the shape of central spray outlet 12. Consequently, washing water can be sprayed to objects to be washed in a desired direction and in an optimum spray shape.
Meanwhile, as to second spray outlet 11 (excluding central spray outlet 12), consideration is needed for the balance of downward moment caused by a spray reactive force with rotation center C2 of second arm nozzle 7 as a supporting point. That is to say, a loss of the balance of the moment causes leakage of washing water due to a rotation defect of second arm nozzle 7 and a sealing defect at rotation sealing part 9, which can fail to provide given wash performance.
Hence, the dishwasher of this exemplary embodiment is provided with the members of second spray outlet 11 (excluding central spray outlet 12) disposed at positions point-symmetrical with respect to rotation center C2 of second arm nozzle 7. This allows second arm nozzle 7 to be always balanced by vertical spray reactive forces with rotation center C2 as a supporting point, thereby providing stable wash performance.
As described above, the dishwasher of the present invention includes a washing tub for containing wash objects; a washing pump for pressure-circulating washing water inside the washing tub; and a wash nozzle communicating with the washing pump for spraying the washing water to wash the wash object. The wash nozzle is composed of a rotatable first arm nozzle and a second arm nozzle. The second arm nozzle has a plurality of washing water spray openings and its rotation center at a position decentered from the rotation center of the first arm nozzle; is rotatably provided on the first arm nozzle through a hook-and-catch locking part. The second arm nozzle is provided with at least one washing water spray opening on a top surface above directly the rotation shaft (the vertical water path linking with the first arm nozzle). This prevents the ratchet fitting part of the second arm nozzle from detaching due to a dynamic water pressure at startup of the washing pump, thereby providing a dishwasher with a small number of parts and high maintenance workability.
Further, the dishwasher of the present invention may be provided with a plurality of washing water spray openings other than the one directly above the rotation shaft of the second arm nozzle so that they are point-symmetrical with respect to the rotation center of the second arm nozzle. This allows the second arm nozzle to be rotated in a state where vertical spray reactive forces with the rotation center as a supporting point are always balanced, thereby providing a dishwasher with more stable wash performance.

Claims

A dishwasher comprising:
a washing tub for containing a wash object;

a washing pump for pressure-circulating washing water inside the washing tub; and

a wash nozzle communicating with the washing pump for spraying the washing water to wash the wash object,
wherein the wash nozzle includes a rotatable first arm nozzle and a second arm nozzle, the second arm nozzle having a plurality of washing water spray opening and a rotation center at a position decentered from a rotation center of the first arm nozzle, and rotatably provided on the first arm nozzle through a hook-and-catch locking part, and wherein the second arm nozzle has at least one of the washing water spray openings on a top surface above a rotation shaft that corresponds to a vertical water path linking to the first arm nozzle.
The dishwasher of claim 1, wherein the plurality of washing water spray openings other than the one directly above the rotation shaft of the second arm nozzle are disposed point-symmetrically with respect to the rotation center of the second arm nozzle.