EP2459048A1

EP2459048A1 - Dishwasher

Info

Publication number: EP2459048A1
Application number: EP10765666A
Authority: EP
Inventors: Michele Sculco; Alessandro Gadaleta
Original assignee: Indesit Co SpA
Current assignee: Whirlpool EMEA SpA
Priority date: 2009-07-28
Filing date: 2010-07-26
Publication date: 2012-06-06
Also published as: WO2011013057A1

Abstract

The present invention relates to a dishwashing machine of the type comprising a tub (1) that can be opened and closed frontally with a door (2), which tub (1) houses at least one extractable rack (3), and further comprising at least one slide guide (5) for guiding the rack (1) as it is being extracted to a remote position relative to the tub (1), wherein said slide guide (5) is secured to one wall of the tub (1), in particular to one of the vertical side walls thereof, and wherein the slide guide (5) comprises a movable guide (52) for keeping the rack (3) engaged with the guide (5) when the rack (3) is in a remote position relative to the tub (1), wherein said slide guide (5) rests at least partly on a horizontal wall of said tub (1).

Description

DISHWASHER

DESCRIPTION

The present invention relates to a dishwashing machine comprising an improved rack guide.

hi this description and in the appended claims, the term "dishwashing machine" will refer to a machine adapted to carry out washing operations onto crockery such as pots, flatware, glassware, dishes and the like, typically for household use.

Dishwashing machines usually comprise a front-loading tub that can be opened and closed frontally with a door, wherein sprayers are arranged which spray water and washing agents onto the crockery placed inside two racks, i.e. an upper rack and a lower rack.

hi order to allow the user to comfortably load and unload the crockery into/from the racks, the latter can normally be extracted through the front opening of the tub.

This solution is attainable in different ways. Normally the upper rack is hung to the tub walls and slides out on suitable guides, whereas the lower rack, when extracted, rests on the dishwasher's door, in particular on the inner panel thereof, and is fitted with wheels.

The lower rack is guided by fixed rail-like metal guides applied internally to the tub walls.

Such a solution is shown, for example, in patent GB 1202013 to PHILIPS: in this solution, the lower rack is provided with four wheel pairs in order to distribute the load evenly onto the bottom surface of the tub.

hi this solution, the rail-like guide is fixed and is arranged on the opposed side walls of the tub: when the lower rack is extracted from the cavity of the tub, it rests with its wheels on the machine's door (which in this condition extends horizontally), and the rack is disengaged from the guide.

More in detail, according to this solution only the rearmost wheel pair (i.e. the one closer to the tub) is engaged with the guide when the rack is fully extracted: in this respect, it can be stated that the engagement between the rack and the guide is not stable, since the rack is free to rotate vertically about the horizontal axis common to the two wheels of the wheel pair engaging the guide and, to a certain extent, it can also rotate slightly about a vertical axis due to construction tolerances.

This implies the risk that, as it is being inserted, the rack may turn slightly over itself (in a horizontal plane), thus preventing the other wheel pairs from entering correctly into the guides and applying stresses to the latter which might damage them.

Moreover, in this solution the guides of the lower rack and those of the upper rack overhang from the walls and are secured thereto by means of simple screws; they are therefore typically made of metal sheet (e.g. sheet steel or the like) to withstand the stresses caused by the weight of the rack loaded with crockery and those caused by the rack being extracted from and inserted into the tub.

However, in the event that a rack has been loaded excessively (e.g. beyond the limit recommended by the machine manufacturer), the guides may become deformed and make it difficult to extract the rack.

These metal guides are normally subjected to a surface treatment (e.g. galvanizing and/or coating with an insulating rubber sheath) in order to prevent them from suffering damage caused by the working environment inside the tub of the machine. Furthermore, since the guides are made of metal and are surface-treated, they are rather costly and must be machined mechanically for making the holes required for securing them to the tub walls.

A further drawback is that, when the rack is partially inserted (i.e. when two rear wheel pairs are within the guide), an accidental closing of the door will apply a high torque to the guides, which might thus be damaged: in fact, in such a condition a rack portion is still resting on the door, and any rotation of the latter will be transferred to the rack. Another drawback is that, when the rack is partially inserted (i.e. when two rear wheel pairs are within the guide), an accidental closing of the door will apply a high torque to the guides, which might thus be damaged: in fact, in such a condition a rack portion is still resting on the door, and any rotation of the latter will be transferred to the rack. Yet another drawback is that, as the rack wheels are passing from the tub to the door or vice versa during the extraction or insertion steps, they encounter a difference in height that causes the rack to jolt and possibly damage the crockery contained therein.

The present invention aims at eliminating these and other drawbacks by providing a dishwashing machine which comprises an improved rack guide as set out in the appended claim 1.

A first idea at the basis of the present invention is to provide a dishwashing machine fitted with guides, preferably of the telescopic type, for the lower rack, so as to keep the latter engaged with the guide when it has been extracted and is resting on the door.

The engaged condition implies that two degrees of constraint exist between the rack and the guide, since the only degree of freedom is given by the rigid horizontal translation of the rack relative to the guide.

Another advantageous idea is to provide slide guides that discharge at least a part of the weight-induced stresses onto the tub bottom: to this end, the fixed part of the telescopic slide guides of the present invention rests on the tub bottom.

This allows at least the fixed part of the guide to be made of plastic, thus leading to a significant production cost reduction and simplifying the manufacturing process, since it may be obtained by means of a simple moulding operation.

Yet another advantageous idea is to provide a dishwashing machine equipped with a safety system that prevents the guides from being damaged by a door closing movement when the rack is in the fully or partially extracted conditions.

More in particular, said guides are made to extend to the wheels' transit region between the door and the tub, so as to allow the rack to be easily inserted and extracted.

Further advantageous features will be set out in the appended claims, which are intended as an integral part of the present text.

These features as well as further advantages of the present invention will become apparent from the following description of an embodiment thereof as shown in the annexed drawings, which are supplied by way of non-limiting example, wherein:

Fig. 1 is a side sectional view of parts of a dishwashing machine fitted with a slide guide according to the present invention;

Fig. 2 is a perspective view of a detail of the machine of Fig. 1;

Fig. 3 is an exploded view of the slide guide of Fig. 1;

Fig. 4 is a sectional view of the slide guide of Fig. 3 applied to the tub of Fig. 1;

Fig. 5 shows the guide of Fig. 4 in a condition wherein it houses the rack wheels; Figs. 6a-6d show four consecutive moments of the extraction of the lower rack from the tub of Fig. 1;

Figs. 7a and 7b show two positions of a stop fitted to the guide of Fig. 1 ;

Fig. 8 shows a step of fitting the guide to the tub of Fig. 1;

Figs. 9a, 9b and 9c show three consecutive moments of the extraction of the lower rack from a tub of a dishwasher according to the present invention;

Fig. 10 is an exploded view of the slide guide of Figs. 9a, 9b and 9c;

Fig. 11 is a sectional side view of the slide guide of the dishwasher of Figs. 9a, 9b and

9c;

Fig. 12 is a sectional top view of the slide guide of Fig. 10;

Figs. 13a and 13b show two moments of the intervention of the safety system for the guide of the dishwashing machine of Figs. 9a, 9b and 9c;

Fig. 14 shows a perspective view of a detail of the slide guide of Fig. 10;

Fig. 15 shows parts of a dishwasher fitted with a guide according to the present invention;

Fig. 16 is a sectional view of the guide of Fig. 15;

Figs. 17a-17d show four consecutive moments of the extraction of the lower rack from the tub of Fig. 15;

Figs. 18a- 18b are side views that illustrate two moments of the intervention of the safety system for the guide of the dishwashing machine of Fig. 15;

Fig. 19 is a perspective view of a detail of the guide of Fig. 15.

Referring now to Fig. 1 , there are shown a number of components of a dishwashing machine M equipped with the guide according to the present invention.

hi particular, it shows the tub 1 that in this example houses a lower rack 3 adapted to contain the crockery that will be washed by the machine M.

The tub 1 has a front opening which can be closed with a horizontally-pivoted door 2, shown in Fig. 1 ; through this opening, the rack 3 can be extracted to allow the user to pick up or lay down the crockery from/into the rack 3.

The guides according to the present invention are arranged on two opposed side walls of the tub 1. For simplicity, however, in the following description reference will only be made to one of them, the other one being exactly the same. The rack 3 moves by sliding on the wheel pairs 41, 42 and 43, more clearly visible in

Figs. 6a-6d.

The sliding motion is guided by the slide guide 5, shown in detail in Fig. 3, which comprises a fixed guide 51, a movable guide 52 and an anchor plate 53; the latter is positioned outside the tub 1 and acts as a striker to secure the fixed guide 51 to the tub by means of screws, as will be described more in detail with reference to Figs. 7a and

7b.

The fixed guide 51 has a substantially C-shaped cross-section and accommodates internally, in a movable manner, the guide 52, thus creating some sort of telescopic guide: in order to improve the sliding action and reduce friction, the guide 5 comprises rolling members interposed between and in contact with the fixed guide 51 and the movable guide 52, such as the balls 57 shown in Fig. 4 or rollers or the like, which are for this purpose housed in suitable seats provided on either the movable or the fixed guide.

It should be pointed out that the movable guide 52 also has a substantially C-shaped cross-section and accommodates internally the rear wheels 42 and 43 of the rack 3, thus guiding the rolling action thereof as the rack 3 is sliding.

This feature ensures that the wheels of the rack are guided optimally as the latter is being extracted to the remote position relative to the tub recess, as shown in Figs. 6b and 6c.

In this regard, it must be noted that the rack wheels always stay engaged with the movable guide 52 and prevent the rack from making side-to-side movements which might compromise its stability.

Furthermore, this feature also offers another advantage: as the rack wheels are passing over the region comprised between the tub bottom and the door, the rack 3 is guided more effectively and any sudden movements or jolts are prevented.

Referring back to the fixed guide 51 , it can be seen in Figs. 4 and 5 that it comprises a bottom portion 51a through which it rests on the bottom of the tub 1, so as to discharge onto the latter the stresses caused by the weight of the rack and of any crockery contained therein.

The bottom portion 51a preferably extends over the full length of the fixed guide 51, thus maximising the surface onto which the forces are discharged and ensuring an even distribution thereof.

In the illustrated example, the bottom portion 51a comprises three ribs 51a' extending from the C-shaped body of the fixed guide towards the bottom of the tub 1 ; the ribs 51a' play the role of further stiffening the fixed guide 51 which, being able to discharge the forces onto the tub bottom, may then be made of plastic material, i.e. in a simple manner and at a low production cost.

hi this regard, it should be pointed out right away that the main functional elements of the slide guide 5, e.g. the fixed guide 51 and the sliding guide 52, may advantageously be made of plastic material, which is beneficial in terms of weight reduction and low production costs.

In order to explain how the guide 5 operates, reference will now be made to Figs. 6a-

6d, which show different moments of the step of extracting the rack 3: Initially (Fig.

6a), the rack 3 is in its idle position within the tub 1 ; when the user applies a horizontal force, the rack 3 translates horizontally on the three wheel pairs 41, 42 and 43: in this respect, it should be noted that the rear wheel pairs 42 and 43 of the rack slide within the movable guide 52, whereas the front wheel pair 41, as the rack is being extracted, first rests on the bottom of the tub 1 (Fig. 6a) and then on the open door 2 (Figs. 6c,

6d).

When the rack is extracted, there is a first step wherein the rear wheels 42 and 43 of the rack roll within the movable guide 52, which remains stationary inside the fixed guide 51 (Fig. 6b).

As aforementioned, during the extraction movement the wheels must cross the passage region between the tub bottom and the door: the presence of the movable guide that houses the rear wheel pairs 42 and 43 of the rack ensures that in this step it is not subject to shaking or sudden jolts.

As shown in detail in Figs. 3, 7a and 7b, at its free end facing the door the movable guide 52 has a stop 55 which intercepts the C-shaped passage section of the guide, thereby acting as a striker or stop for the wheel 43.

The latter, in fact, as shown in Fig. 6c, will abut against the stop 55 as the rack 3 will move forwards, and any additional force applied in the rack extraction direction will cause the movable guide 52 to start sliding within the fixed guide 51 (Fig. 6d), thus allowing the rack to be extracted from the recess of the tub 1 by providing a telescopic operation; it should be noted that in this condition the rack 3 is substantially fully extracted from the recess of the tub 1.

In substance, the rack extraction travel is thus subdivided into two parts: a first part wherein the movable guide 52 is stationary relative to the fixed guide 51 and the rack slides relative to the former, and a second part wherein the movable guide 52 slides within the fixed guide 51 and the rack is stationary relative to the former and moves integrally therewith.

In this manner, the wheels 42 and 43 will stay engaged with the movable guide 52 when they come out of the tub.

In this condition (Fig. 6d), the user can pick up the crockery from the rack 3 and then push the latter back into the tub 1 without the latter being able to rotate in the horizontal plane that contains the wheels' axes during the extraction and insertion steps: in fact, the rack 3 is kept engaged with the guide 5 even when it is in the extracted condition. \

The only movement allowed to the rack is the rigid translation relative to the guide in the horizontal direction, i.e. in the direction of re-insertion into the tub; the problems caused by prior-art solutions are thus avoided.

Whenever the rack 3 is to be separated from the movable guide 52, e.g. for in-depth cleaning or maintenance purposes, this is possible thanks to the fact that the stop 55 is removable or movable: as shown in Figs. 7a and 7b, in fact, it is secured to the movable guide 52 in a manner such that it can be moved manually to a remote position relative to the position where it intercepts the passage groove for the wheels 42 and 43; in the example illustrated with reference to Figs. 7a and 7b, the stop 55 is hinged to the movable guide 52 and can be turned about an axis in order to be placed into the remote position of Fig. 7b, wherein it does not intercept the passage groove of the movable guide 52 and thus allows the wheels 42 and 43 to come out of the latter, thereby allowing the user to decouple the rack 3 from the slide guide 5 and consequently remove the rack 3.

Incidentally, it should be pointed out that also the stop 55 may be made of plastic material, and that the hinge may be made in a simple and inexpensive manner by providing the stop with two pins engaging into two matching seats provided on the movable guide.

In the course of the manoeuvre for re-inserting the rack into the tub recess, the wheel 42 starts running inside the groove of the movable guide 52 until it abuts on the second stop 54, when it moves the movable guide in the direction opposite to the extraction direction.

The second stop 54 may either be applied to the rear end of the guide or be made in one piece therewith.

Referring back to the slide guide 5, it is important to point out the functionality of the anchor plate 53 arranged outside the tub 1, which acts as a striker for securing the fixed guide 51 to the wall, being a portion of the side wall of the tub interposed between the anchor plate 53 and the fixed guide 51 when the guide 5 is fitted to the tub 1.

Referring now to Figs. 2, 3, 4 and 8, there is shown that the anchor plate 53 has a plan shape and an extension approximately equal to those of the fixed guide 51.

This allows the load withstood by the latter to be distributed onto an equally large area of the side wall of the tub 1, thus avoiding any point-like or concentrated stresses which would otherwise arise in the absence of the anchor plate 53 if only screws and washers were used.

In this latter case, in fact, the force concentration might lead to formation of cracks in the plastic parts of the guide 5 and possibly to deformation of the side wall of the tub 1 in the washers' mounting positions.

On the contrary, the wide extension of the anchor plate 53 ensures an even distribution of the forces, thus preventing these problems from occurring.

In substance, therefore, the fact that the guide 5 of the present invention discharges most of the stresses it is subjected to onto the tub bottom and only a small part thereof onto the tub walls, combined with the use of a large anchor plate 53, allows to safely employ a guide 5 made of plastic material without incurring in failures or damages. The cooperation between the anchor plate 53 and the fixed guide 51 ensures that the sealing Hp 51c of the latter is compressed against the side wall of the tub, thereby providing an optimum watertight seal even if no gaskets are used: this effect is maximised by the fact that the screws 60 are positioned centrally relative to the edge 51c, resulting in a sort of "suction cup effect" that ensures a watertight seal.

Such an effect is also caused by the fact that the guide is made of plastic, and thus, when the anchor plate is tightened by means of the screws 60, the fixed guide 51 and therefore also the sealing lip are compressed against the tub wall, thus ensuring a proper seal.

As an alternative, it is conceivable to add a gasket matching the lip 51c to improve the sealing performance.

Referring now to Fig. 4, there is shown a cross-section of the coupling region between the fixed guide 51 and the anchor plate 53: the fixed guide 51 is fitted with hollow pins 51b which engage into matching seats 53b in the anchor plate 53; the hollow pins 51b may be threaded internally and secured to the anchor plate through the screws 60, so as to make the coupling sufficiently stable and sturdy without at the same time stressing the plastic parts too much.

Of course, in a possible variant the guide may be of a type other than the telescopic one shown in the example, therefore lacking the movable guide 52: in such a case the fixed guide 51 itself will provide the wheel guiding groove.

As an alternative, it is of course conceivable that also the guides for the upper rack are made as just described; in such a case, the guide may discharge the vertical load onto a suitable convex or raised portion obtained on the tub's side walls, e.g. by dishing the latter appropriately.

In accordance with the above, the present invention also relates to a method for securing a slide guide 5 in a dishwashing machine of the type comprising a tub 1 that can be opened and closed frontally with a door 2, which tub 1 houses at least one extractable rack 3, wherein the slide guide 5 is adapted to guide the rack 1 as it is being extracted to a remote position relative to the tub 1 , said slide guide 5 being secured to one wall of the tub 1, in particular to one of the vertical side walls thereof, and wherein the slide guide 5 comprises a movable guide 52 for keeping the rack 3 engaged with the guide 5 when the rack 3 is in a remote position relative to the tub 1, and wherein the method comprises the step of laying said slide guide 5 at least partly on a horizontal wall of the tub 1.

Referring now to Figs. 9a-9c, there is shown an alternative embodiment of the dishwashing machine M' fitted with a slide guide 5' according to the present invention; more in detail, there is shown the tub 1', which in this example houses a lower rack 3 ' adapted to contain the crockery that will be washed by the machine.

The tub I' has a front opening closed by the horizontally-pivoted door 2', shown in Figs. 9a-9c in the condition in which it leaves the tub 1' open (door positioned horizontally); the door 2' is typically hinged to the tub and rotatable relative thereto. Through the opening closed by the door 2', the rack 3' can be extracted to a remote position away from the tub, where it rests on the door, in order to allow the user to pick up or lay down the crockery from/into the rack.

The slide guides 5' according to the present invention are arranged on two opposed side walls of the tub 1'. For simplicity, however, in the following description reference will only be made to one of them, the other one being exactly the same.

Fig. 10 shows the slide guide 5', which comprises the fixed striker 51' and the movable guide 52'.

The fixed guide 51' comprises in turn a disengageable safety support 51a', a guide support 51b', the anchor plate 5 Id' and wheels 51c' secured to pins provided on the disengageable safety support 51a'; the function of the disengageable safety support 51a' will be made clear later on.

The movable guide 52' comprises the slot 52a', which provides the seat that houses the small wheels 51c' of the fixed striker 51'.

Referring back to Figs. 9a-9c, it can be noticed therein that the rack 3' comprises three wheel pairs 41', 42' and 43': when the rack is inside the tub (Fig. 9a), the three wheel pairs 41', 42' and 43' rest on the tub bottom, whereas in the extracted condition (Fig. 9c) they rest on the door 2'.

The movement of the rack between the inserted condition (Fig. 9a) and the extracted condition (Fig. 9c) is accomplished when the rack 3' is pulled out and slides on the wheel pairs 41', 42' and 43', as shown in Fig. 9b.

As can be seen, the rear wheel pairs 42' and 43' associated with the rack are guided by the slide guides 5'. The movable guides 52' arranged on the side walls of the tub 1', in fact, operate as upper rails for the wheel pairs 42', 43', i.e. for that wheel pair 42' which is positioned at the end of the rack 3' facing the tub and for the intermediate wheel pair 43' positioned between the first wheel pair and the wheel pair 41 ' associated with the end of the rack 3 ' facing the door 2 ' .

These latter wheels 41' are not engaged into the movable guide 52'.

Note the presence of the stop 53', also shown in detail in Fig. 14, which acts as a striker for the wheels 43' as the rack is moving forwards when extracted, as shown in Fig. 9b.

The operation can be understood by observing Figs. 9a-9c, which show three consecutive moments of the step of extracting the rack 3' from the tub 1': the rack 3' is initially inside the tub 1', and its wheels 41', 42' and 43' rest on the bottom of the tub 1'; then the user grips and pulls the rack 3', thus causing it to start moving: for a first section (until the condition shown in Fig. 9b is obtained, i.e. when the wheels 43' abut on the stop 53'), the movable guide 52' remains stationary; then, for a second section (following the condition shown in Fig. 9b), the movable guide 52' is dragged outwards integrally with the rack 3' through the effect of the wheels 43', which have abutted on the stop 53' integral with the guide 52'.

The motion of the movable guide 52' is guided by means of the slot 52a', which slides relative to the small wheels 51c', which stay fixed relative to the disengageable safety support 5 Ia'.

In this manner, the wheels 42' and 43' will stay engaged with the movable guide 52' when they come out of the tub and come to rest on the door.

In this condition (Fig. 9c), the user can pick up the crockery from the rack 3' and then push the latter back into the tub 1' without the latter being able to rotate in the horizontal plane that contains the wheels' axes during the extraction and insertion steps: in fact, the rack 3' is kept engaged with the guide 5' even when it is extracted and resting on the door 2'.

The only movement allowed to the rack is the rigid translation relative to the guide in the horizontal direction, i.e. in the direction of re-insertion into the tub; the problems caused by prior-art solutions are thus avoided. As can be seen in Fig. 10 and Figs. 11 and 12, the small wheels 51c' are supported by the pins integral with the disengageable safety support 51a', which in turn is snapped onto the guide support 51b', which in turn is stably secured to the anchor plate 5 Id' arranged outside the tub.

Note that the snap-on mounting of the disengageable safety support 51a' on the guide support 51b' is obtained in that the guide support 51b' has a raised tooth 91' projecting from the face thereof on the side of the disengageable safety support 51a' in the properly installed condition (as shown).

The disengageable safety support 51a', in its turn, has an elongated shape and includes an engagement notch 92' at one end and a forked notch 93' at the opposite end.

hi the installed condition, the forked notch 93' fixedly embraces the pin 95' of the guide support 51b', and the engagement notch 92' is snapped on the tooth 91' of the guide support 51b'.

Of course, it must be pointed out right away that the forked notch 93' may be replaced with a simple hole made in the disengageable safety support 51a'.

When the rack 3' is in the extracted condition (as in Fig. 9c) or in the partially extracted condition (as in Fig. 9b), an inappropriate attempt to close the door 2', which would otherwise stress the guide 5', will cause no harm with this solution, due to the presence of the safety system just described: in fact, with reference to Figs. 13a and 13b, in the event that a manoeuvre for closing the door 2' is made which rotatably drags the rack or, alternatively, if the rack 3' is subjected to a rotating movement of any kind, the engagement notch 92' will disengage from the tooth 91', thus leaving the rack 3' free to rotate about the horizontal axis defined by the pin 95'.

It must be pointed out that in this manner the entire movable guide 52' will also rotate integral with the rack 3', thereby advantageously preventing the guide from disengaging from the rack and making the return to the working position easier.

Thus, a wrong manoeuvre for closing the door with the rack positioned remotely from the tub (whether completely or partially extracted therefrom or in any condition in which the front wheel pair 41' is still resting on the door 3') will apply a stress to the guide 5' which will be transmitted to the disengageable safety support 51a', which in turn will disengage from the fixed support 51b', thereby preventing the latter or the anchor plate 5 Id' or the movable guide 52' from suffering any damage and eliminating the drawbacks of prior-art solutions.

It should be highlighted that the fact that the movable guide 52' is snap-engaged with the fixed striker 51' so as to disengage the movable guide 52' from the fixed striker 51' itself when the remotely positioned rack 3' is turned relative to a horizontal axis also allows the movable guide or possibly the whole slide guide 5' to be safely made of plastic, since such a solution reduces the risk of damage in case of improper use.

Reference will now be made to Figs. 10 and 11, wherein a further advantageous feature of the present invention can be appreciated.

In fact, the anchor plate 5 Id' has a plan shape and an extension approximately equal to those of the guide support 51b'.

This allows the load withstood by the latter to be distributed onto an equally large area of the side wall of the tub 1', thus avoiding any point-like or concentrated stresses which would otherwise arise in the absence of the anchor plate 5 Id' if only screws and washers were used.

hi this latter case, in fact, the force concentration might lead to formation of cracks in the plastic parts of the guide 5' and possibly to deformation of the side wall of the tub

1 ' in the washers' mounting positions.

On the contrary, the wide extension of the anchor plate 5 Id' provides an even distribution of the forces, thus preventing these problems from occurring.

The presence of a large anchor plate 5 Id' allows to safely employ a guide 5' made of plastic material without incurring in failures or damages.

The cooperation between the anchor plate 5 Id' and the fixed guide 51b' ensures that the edge 5 Ie' of the latter acts as a sealing lip which is compressed against the side wall of the tub, thereby providing an optimum watertight seal even if no gaskets are used: this effect is maximised by the fact that the screws 60' are positioned centrally relative to the edge 51c', resulting in a sort of "suction cup effect" that ensures a watertight seal.

Such an effect is also caused by the fact that the guide is made of plastic, and thus, when the anchor plate is tightened by means of the screws 60', the guide 51b' and therefore also the sealing lip 5 Ie' are compressed against the tub wall, thus providing a proper seal.

As an alternative, it is conceivable to add a gasket matching the lip 5 Ie' to improve the sealing performance.

A further advantageous feature can be observed in Fig. 14: there is shown, in fact, that the stop 53' is removable, and can therefore be extracted from its seat on the movable guide 52'.

It is positioned in a manner such that it intercepts the lower region of the movable guide 52' where the wheels 42' and 43' pass, so as to allow the movable guide 52' itself to be dragged outwards in the sliding direction as previously described with reference to Figs. 9a-9c.

The reason for existence of the stop 53' is to ensure that the rack 3' can be separated from the guide, e.g. for cleaning purposes or the like.

In accordance with the above description, the present invention also relates to a method for preventing damage to a rack guide of a dishwashing machine of the type previously described, wherein the slide guide 5' is at least partly disengageable from said side wall of the tub when the remotely positioned rack 3' is turned about a horizontal axis.

Still in accordance with the above, it is a further object of the present invention to provide a method for guiding the sliding action of a rack of the above-described dishwashing machine, wherein the rack is kept engaged with the guide 5' as it is sliding to and from its remote position.

Another advantageous feature is shown in the embodiment illustrated in Fig. 15, which shows a side view of parts of a dishwashing machine M" fitted with a guide 5" according to the present invention; more in detail, it shows the tub 1" that in this example houses a lower rack 3" adapted to contain the crockery that will be washed by the machine.

The dishwashing machine further comprises a slide guide 5" adapted to guide the rack

3" during a step of extracting it to a remote position relative to the tub 1 ".

The slide guide 5" is secured to one of the vertical side walls of the tub 1"; in the illustrated example there are two slide guides for each vertical side wall of the tub adjacent to the opening of the latter. In accordance with the teachings of the present invention, the slide guide 5" comprises a fixed support 52" applied to the side walls of the tub, with which a disengageable safety support 51" is associated.

The latter is adapted to guide the rack as it is being extracted from the tub, and is associated by means of a snap-on coupling with the fixed support 52", so as to disengage from the latter in the event that the rack 3" is turned over, as will be described more in detail with reference to Figs. 18a and 18b.

hi the example provided, the rack comprises three wheel pairs 41 ",42 ",43"; the wheels are arranged in pairs on the opposite sides of the rack facing the respective guides 5".

The disengageable safety support 51 "extends inside the tub and has a "C" shape that defines a groove 51a adapted to house the wheels 41 ",42 ",43" and guide them as the rack is being extracted to a remote position relative to the tub, as shown in Figs. 17a- 17c, which will be described later on.

As can be seen, the slide guide 5" comprises a bearing portion 54" which extends in the region between the door 2" and the bottom of the tub 1", and which is adapted to provide a bearing surface for the rack wheels as the rack is being extracted from or inserted into the tub, so as to prevent the wheels from jolting when crossing this region.

Referring now to Fig. 16, there is shown that the groove 51a" that houses the disengageable safety support 51" comprises at least one lateral extension 51b" protruding inwards in the direction of the wheels.

The function of this lateral extension 51b" is to limit and compensate for production tolerances and for any deformation which may arise during the service life of the guide 5", thus allowing it to be made of plastic material.

It is plain, in fact, that a guide 5" made of plastic material has characteristics of resistance to wear and to the chemical agents used in the wash cycles which are definitely inferior to those of a known metallic guide, but the latter is much more expensive and requires additional mechanical machining in order to be installed (drilling holes and the like).

The presence of the lateral extension 51b" allows to centre the rack wheels and to compensate (due to its elasticity) for any tolerances which may arise over time.

In fact, to this end it is sufficient that the lateral extension 51b" has dimensions such that it stays slightly in contact with the wheels: with the passing of time it may deform and become less convex, thus losing contact with the wheels, but the centering of the latter in the guides will still be accurate enough.

With reference to Figs. 17a- 17c, it can be seen that when the rack 3" is inside the tub (Fig. 17a) the three wheel pairs 41", 42" and 43" rest on the guide 5", which therefore acts as some sort of rail that extends at least partly above and under the wheels.

In the extracted condition (Fig. 17c), the central wheel pair 43" rests on the guide 5", whereas the front wheels 41" rest on the door 2" and the rear wheels 42" rest on the bottom or lower horizontal surface of the tub.

As the rack is being moved from the condition in which it is inside the tub (Fig. 17a) to the extracted condition (Fig.17c), the front wheel pair 41" must cross the space between the tub bottom and the door 2" .

The rack 3" comes out by sliding on the wheel pairs 41", 42" and 43", and the presence of the bearing portion 54" allows the front wheels 41" to cross this area smoothly without jolting.

As can be seen, the rear wheel pairs 42" and 43" associated with the rack stay engaged with the guide 5" even when the rack 3" has been fully extracted from the tub.

The disengageable safety support 51" arranged on the side walls of the tub 1 " acts as an upper rail for all wheel pairs 41", 42", 43"; it also acts at least partly as a lower rail (in the section closer to the door) thanks to the bearing portion 54" for the wheel pairs 41", 43" only, i.e. for the wheel pair 41" arranged at the front end of the rack 3" facing the door and for the intermediate wheel pair 43" arranged between the first one and the wheel pair 42" associated with the rear end of the rack 3".

In substance, the bearing portion 54" is provided in the form of a flat portion of the guide which supports the wheels, and is substantially coplanar to the horizontal bottom surface of the tub and to the door when the latter is leaving the tub open.

The operation can be understood by observing Figs. 17a- 17c, which show three consecutive moments of the step of extracting the rack 3" from the tub 1 : the rack 3" is initially inside the tub 1", and the wheels 41", 42" and 43" are engaged by the guide 5".

When the user grips the rack 3" and pulls it out, the rack begins moving: because of the presence of the bearing portion 54", the front wheels 41" only undergo a slight bounce when passing from the tub to the outside.

When the rack 3" is in the remote position relative to the tub, the wheels 42" and 43" and a residual portion of the rack remain inside the tub, as shown in Fig. 17c.

It should also be noted that in this condition (Fig. 17c) the user can pick up the crockery from the rack 3" and then push the latter back into the tub 1" without the latter being able to rotate in the horizontal plane that contains the wheels' axes during the extraction and insertion steps: in fact, the rack 3" is kept engaged with the guide

5" even when it is in the extracted condition.

Referring now to Fig. 15 and to Figs. 18a and 18b, there is shown the safety system that prevents the guides from being damaged in the event that the user accidentally closes the door 2" when the rack 3" is resting on it.

For this purpose, the fixed support 52" comprises a raised tooth 91" and a pin 95" projecting from the face thereof on the side of the disengageable safety support 51" in the installed condition.

hi its turn, the disengageable safety support 51" comprises an engagement notch

92"at one end and a forked notch 93" at the opposite end.

In the installed condition, the forked notch 93" fixedly embraces the pin 95" and the engagement notch 92" is snapped on the tooth 91" of the fixed support 52", so as to provide a snap-on engagement between the disengageable safety support 51" and the fixed support 52".

Of course, it must be pointed out right away that the forked notch 93" may be replaced with a simple hole made in the disengageable safety support 51a".

When the rack 3" is in the extracted condition (as in Fig. 17c) or in the partially extracted condition (as in Fig. 17b), an inappropriate attempt to close the door 2", which would otherwise stress the guide 5", will cause no harm with this solution, due to the presence of the safety system just described: in fact, with reference to Figs. 18a and 18b, in the event that a manoeuvre for closing the door 2" is made or, alternatively, if the rack 3" is subjected to a rotating movement, the engagement notch 92" will disengage from the tooth 91", thus leaving the rack 3" free to rotate about the horizontal axis defined by the pin 95".

It must be pointed out that in this manner the entire disengageable safety support 51" will also rotate integral with the rack 3", thereby advantageously preventing the disengageable safety support 51" from disengaging from the rack and making the return to the working position easier.

Thus, a wrong manoeuvre for closing the door with the rack positioned remotely from the tub (whether completely or partially extracted therefrom or in any condition in which the front wheel pair 41" is still resting on the door 3") will apply a stress to the guide 5" which will be transmitted to the disengageable safety support 51", which in turn will disengage from the fixed support 52", thereby preventing the latter or the anchor plate 53" from suffering any damage and eliminating the drawbacks of prior- art solutions.

Referring now to Figs. 15, 16 and 19, there is shown the anchor plate 53" that can be positioned outside the tub in order to secure the fixed support 52" to a side wall of the tub.

This anchor plate has a plan shape and an extension substantially equal to those of said fixed support 52".

This allows the load withstood by the latter to be distributed onto an equally large area of the side wall of the tub 1", thus avoiding any point-like or concentrated stresses which would otherwise arise in the absence of the anchor plate 53" if only screws and washers were used.

hi this latter case, in fact, the force concentration might lead to formation of cracks in the plastic parts of the guide 5" and possibly to deformation of the side wall of the tub 1 " in the washers' mounting positions.

On the contrary, the wide extension of the anchor plate 53" ensures an even distribution of the forces, thus preventing these problems from occurring.

The presence of a large anchor plate 53" allows to safely employ a guide 5" made of plastic material without incurring in failures or damages.

The cooperation between the anchor plate 51d" and the fixed guide 51b" ensures that the edge 5 Ie' of the latter is compressed against the side wall of the tub, thereby providing an optimum watertight seal even if no gaskets are used: this effect is maximised by the fact that the screws 60" are positioned centrally relative to the edge

51c', resulting in a sort of "suction cup effect" that ensures a watertight seal.

Such an effect is also caused by the fact that the guide is made of plastic, and thus, when the anchor plate is tightened by means of the screws, the guide and therefore also its peripheral sealing lip are compressed against the tub wall, thus ensuring a proper seal.

As an alternative, it is conceivable to add a gasket to improve the sealing performance.

It must also be pointed out that other alternative embodiments are nonetheless conceivable wherein the features of the different examples described above and shown in Figs. 1 to 8, 9a to 14 and 15 to 19 are variably combined together without departing from the scope and teachings of the present invention.

Claims

1. A dishwashing machine of the type comprising a tub (1) that can be opened and closed frontally with a door (2), which tub (1) houses at least one extractable rack (3), and further comprising at least one slide guide (5) for guiding the rack (1) as it is being extracted to a remote position relative to the tub (1), wherein said slide guide (5) is secured to one wall of the tub (1), in particular to one of the vertical side walls thereof, and wherein the slide guide (5) comprises a movable guide (52) for keeping the rack (3) engaged with the guide (5) when the rack (3) is in a remote position relative to the tub (l),

characterised in that

said slide guide (5) rests at least partly on a horizontal wall of said tub (1).

2. A dishwashing machine according to claim 1, wherein the slide guide (5) comprises a fixed guide (51) stably associated with the tub (1) and comprising a groove adapted to house the movable guide (52).

3. A dishwashing machine according to claim 1 or 2, wherein said fixed guide (51) comprises a bottom portion (51 a) resting on a horizontal bottom wall of said tub.

4. A dishwashing machine according to any one of claims 1 to 3, wherein the rack (3) comprises wheels (42,43) housed in a wheel housing groove (42,43) of the movable guide (52).

5. A dishwashing machine according to any one of claims 2 to 4, wherein the slide guide (5) also comprises an anchor plate (53) to be positioned outside the tub in order to secure the fixed guide (51) to a side wall of the tub, and wherein said anchor plate (53) has a plan shape and an extension substantially equal to those of the fixed guide (51).

6. A dishwashing machine according to any one of the preceding claims, wherein the movable guide (52) comprises, at the free end thereof facing the door (2), a stop (55) which intercepts the passage cross-section of the guide groove, thus acting as a striker for one of said rack wheels (42,43).

7. A dishwashing machine according to any one of the preceding claims, wherein the travel of the rack (3), when extracted from the tub (1), is subdivided into two parts: a first part wherein the movable guide (52) is stationary relative to the fixed guide (51) and the rack (3) slides relative to the former, and a second part wherein the movable guide (52) slides within the fixed guide (51) and the rack (3) is stationary relative to the former and moves integrally therewith.

8. A dishwashing machine according to claim 6 or 7, wherein the stop (55) is removable or movable, so that it can be moved to a remote position from the position where it intercepts the passage groove of the movable guide (52).

9. A dishwashing machine according to one or more of claims 2 to 8, wherein the guide (5) comprises rolling members (57) interposed between the fixed guide (51) and said movable guide (52) and in contact with both said fixed guide (51) and said movable guide (52).

10. A dishwashing machine according to one or more of the preceding claims, wherein the slide guide (5) is made of plastic material.

11. A method for securing a slide guide (5) in a dishwashing machine of the type comprising a tub (1) that can be opened and closed frontally with a door (2), which tub (1) houses at least one extractable rack (3), wherein the slide guide (5) is adapted to guide the rack (1) as it is being extracted to a remote position relative to the tub (1), said slide guide (5) being secured to one wall of the tub (1), in particular to one of the vertical side walls thereof, and wherein the slide guide (5) comprises a movable guide (52) for keeping the rack (3) engaged with the guide (5) when the rack (3) is in a remote position relative to the tub (1),

characterised in that

it comprises the step of laying said slide guide (5) at least partly on a horizontal wall of said tub (1).

12. A dishwashing machine of the type comprising a tub (1') that can be opened and closed frontally with a door (2'), which tub (1') houses at least one extractable rack

(3'), and also comprising at least one slide guide (5') adapted to guide the rack (1') as the latter is being extracted to a remote position relative to the tub (1 '), wherein in said remote position the rack (3') rests at least partly on the door (2'), and wherein said slide guide (5') is secured to one of the vertical side walls of the tub (V),

characterised in that

the slide guide (5') comprises a movable guide (52') for keeping the rack (3') engaged with the guide (5') when the rack (3') is in a remote position relative to the tub (V).

13. A dishwashing machine according to claim 12, wherein the slide guide (5') further comprises a fixed striker (51') integral with the walls of said tub (1'), said fixed striker (51') being adapted to support and engage said movable guide (52').

14. A dishwashing machine according to claim 13, wherein the fixed striker (51') comprises a disengageable safety support (5Ia'), a guide support (5Ib'), an anchor plate (5Id') and wheels (5Ic') integral with the disengageable safety support (5Ia'), and wherein the movable guide (52') comprises a slot (52a') adapted to house said wheels (5Ic').

15. A dishwashing machine according to one or more of claims 12 to 14, wherein the rack (3') comprises multiple wheel pairs (41',42',43'), and wherein the movable guide (52') is arranged above said wheels, thus acting as an upper rail for the wheel pair (42') located at the end of the rack (3') that faces the tub (1') and for the intermediate wheel pair (43') located between the first one and the one (41') which is associated with the end of the rack (3') that faces the door (2').

16. A dishwashing machine according to one or more of claims 12 to 15, wherein the movable guide (52') comprises a removable stop (53') that intercepts the lower part of the movable guide (52'), thus allowing the movable guide (52') to be dragged outwards in the sliding direction because of the engagement with one wheel pair (43').

17. A dishwashing machine according to any one of claims 12 to 16, wherein the travel of the rack (3'), when extracted from the tub (1'), is subdivided into two parts: a first part wherein the movable guide (52') is stationary relative to the fixed striker (51') and the rack (3') slides relative to the former, and a second part wherein the movable guide (52') slides relative to the fixed striker (51') and the rack (3') is stationary relative to the former and moves integrally therewith.

18. A dishwashing machine according to one or more of claims 14 to 17, wherein said movable guide (52') is snap-engaged with said fixed striker (51'), in a manner such that said movable guide (52') is disengaged from said fixed striker (51') when the remotely positioned rack (3') is turned about a horizontal axis.

19. A dishwashing machine according to claim 18, wherein said wheels (5Ic') are supported by the integral pins of the disengageable safety support (5Ia'), said disengageable safety support (5Ia') being snapped onto said guide support (5Ib'), and said guide support (5Ib') being stably secured to said anchor plate (5Id') arranged outside the tub (1 ').

20. A dishwashing machine according to claim 19, wherein said guide support (5Ib') comprises a raised tooth (91') and a pin (95') projecting from the face thereof on the side of the disengageable safety support (5Ia') in the installed condition, and wherein the disengageable safety support (5Ia') comprises an engagement notch (92') at one end and a forked notch (93') at the opposite end, in the installed condition said forked notch (93') being adapted to fixedly embrace the pin (95') and said engagement notch (92') being adapted to snap onto the tooth (91') of the guide support (5Ib'), so as to provide said snap-on engagement between the disengageable safety support (5Ia') and the guide support (5Ib').

21. A dishwashing machine according to any one of claims 14 to 20, wherein said anchor plate (5Id') that can be positioned outside the tub in order to secure the guide support (5Ib') to a side wall of the tub has a plan shape and an extension substantially equal to those of said guide support (5Ib').

22. A method for preventing damage to a rack guide of a dishwashing machine, said machine being of the type comprising a tub (1') that can be opened and closed frontally with a door (2'), which tub (1') houses at least one extractable rack (3'), and also comprising at least one slide guide (5') adapted to guide the rack (1') as the latter is being extracted to a remote position relative to the tub (1'), wherein in said remote

)

position the rack (3") rests at least partly on the door (2'), and wherein said slide guide

(5') is secured to one of the vertical side walls of the tub (V),

characterised in that

the slide guide (5') is at least partly disengageable from said side wall of the tub when the remotely positioned rack (3') is turned about a horizontal axis.

23. A method for guiding a sliding rack of a dishwashing machine, the dishwashing machine being of the type comprising a tub (1') that can be opened and closed frontally with a door (2'), which tub (T) houses at least one extractable rack (3'), and also comprising at least one slide guide (5') adapted to guide the rack (1') as the latter is being extracted to a remote position relative to the tub (1'), wherein in said remote position the rack (3') rests at least partly on the door (2'), and wherein said slide guide (5') is secured to one of the vertical side walls of the tub (1'),

characterised in that

the rack is kept engaged with the guide (5') as it is sliding to and from said remote position.

24. A dishwashing machine of the type comprising a tub (1") that can be opened and closed frontally with a door (2"), which tub (1") houses at least one extractable rack (3"), and also comprising at least one slide guide (5") adapted to guide the rack (1") as the latter is being extracted to a remote position relative to the tub (1"), wherein said slide guide (5") is secured to one of the vertical side walls of the tub (1"), characterised in that

the slide guide (5") comprises at least one fixed support (52") applied to the side walls of the tub and a disengageable safety support (51") adapted to guide the rack as the latter is being extracted to a remote position relative to the tub, the disengageable safety support (51") being associated with the fixed support (52") through a snap-on coupling so as to disengage from the latter in the event that the rack (3") is turned about a horizontal axis.

25. A dishwashing machine according to claim 24, wherein the rack (3") comprises multiple wheel pairs (41",42",43"), and wherein the disengageable safety support (51") extends inside the tub and comprises a groove (5Ia") adapted to house said wheels (41 ",42 ",43") for guiding the latter as the rack is being extracted to a remote position relative to the tub.

26. A dishwashing machine according to claim 24 or 25, wherein said housing groove (5Ia") of the disengageable safety support (51") comprises at least one lateral extension (5 Ib") protruding towards the inside of said housing groove (51 a' ').

27. A dishwashing machine according to one or more of claims 24 to 26, wherein said fixed support (52") comprises a raised tooth (91 ") and a pin (95") projecting from the face thereof on the side of the disengageable safety support (51") in the installed condition, and wherein the disengageable safety support (51") comprises an engagement notch (92") at one end and a forked notch (93") at the opposite end, in the installed condition said forked notch (93") being adapted to fixedly embrace the pin (95") and said engagement notch (92") being adapted to snap onto the tooth (91") of the fixed support (52"), so as to provide said snap-on engagement between the disengageable safety support (51") and the fixed support (52").

28. A dishwashing machine according to one or more of claims 24 to 27, wherein said slide guide (5") comprises an anchor plate (53") to be positioned outside the tub in order to secure the fixed support (52") to a side wall of the tub, which anchor plate (53") has a plan shape and an extension substantially equal to those of said fixed support (52").

29. A dishwashing machine according to one or more of claims 25 to 28, wherein the disengageable safety support (51 ") creates an upper rail for all wheel pairs (41 ", 42",

43") of the rack, and wherein the disengageable safety support (51") comprises a bearing portion (54") that creates a lower rail, at least in the transit region between the tub and the door, for the wheel pair (41") arranged at the front end of the rack (3") on the door side and for the intermediate wheel pair (43") arranged between the first one and the one (42 ' ' ) associated with the rear end of the rack (3 " ) .

30. A dishwashing machine according to one or more of claims 24 to 29, wherein said bearing portion (54") extends in the region between the door (2") and the bottom of the tub (1"), and is adapted to provide a bearing surface for said rack wheels.

31. A dishwashing machine according to one or more of claims 23 to 30, wherein said slide guide (5") is made of plastic material.

32. A dishwashing machine of the type comprising a tub (1") that can be opened and closed frontally with a door (2"), which tub (1") houses at least one extractable rack (3"), and also comprising at least one slide guide (5") adapted to guide the rack (1") as the latter is being extracted to a remote position relative to the tub (1"), wherein said slide guide (5") is secured to one of the vertical side walls of the tub (1"), the rack being equipped at the bottom with multiple wheel pairs,

characterised in that

the slide guide (5") comprises a bearing portion (54") extending in the region between the door (2") and the bottom of the tub (1"), which bearing portion (54") extends horizontally and is adapted to provide a bearing surface for said rack wheels.

33. A method for preventing damage to a rack guide of a dishwashing machine, said machine being of the type comprising a tub (1") that can be opened and closed frontally with a door (2"), which tub (1") houses at least one extractable rack (3"), and also comprising at least one slide guide (5") adapted to guide the rack (1") as the latter is being extracted to a remote position relative to the tub (1"), wherein in said remote position the rack (3") rests at least partly on the door (2"), and wherein said slide guide (5") is secured to one of the vertical side walls of the tub (1"),

characterised in that

the slide guide (5") is at least partly disengageable from said side wall of the tub when the remotely positioned rack (3") is turned about a horizontal axis.