EP2165636B1

EP2165636B1 - Hood-type industrial dishwasher

Info

Publication number: EP2165636B1
Application number: EP08425622A
Authority: EP
Inventors: Ezio Gobbi
Original assignee: Bonferraro SpA
Current assignee: Bonferraro SpA
Priority date: 2008-09-23
Filing date: 2008-09-23
Publication date: 2010-11-03
Anticipated expiration: 2028-09-23
Also published as: ATE486517T1; DE602008003339D1; EP2165636A1

Abstract

In a hood-type industrial dishwasher including a hood mounted on vertical guides arranged on the rear wall of the stationary lower part of said dishwasher, so as to slide vertically along the guides with the help of balancing springs (8) suitable to limit the hood opening/closing effort, the guides are telescopic guides (3) including sliding parts (2) on which the hood is secured. The movement of the sliding parts (2) is driven by cables (4) on which the balancing springs (8) act through mobile pulleys (6) arranged on plates (7) that are mounted in a rotatable way on the dishwasher structure, the whole hood moving mechanism being arranged on the back of the dishwasher. In this way, it is possible to dispense with the bulky and potentially dangerous lateral levers and springs by achieving the hood moving through a mechanism fully arranged on the back of the machine. This results in a smaller width of the dishwasher, an increased safety and a great easiness of the external cleaning operations.

Description

The present invention relates to industrial dishwashers, and in particular to a hood-type dishwasher with an improved hood opening/closing mechanism.
It is known that a hood-type dishwasher is substantially divided into a stationary lower half and a mobile upper half (hood) that slides vertically along guides formed in the rear wall of the stationary part. The conventional moving mechanism of the hood includes pins arranged on the two right and left sides thereof which engage corresponding slots formed in a pair of long levers pivoted to the sides of the above-mentioned rear wall. Moreover, in order to limit the hood opening/closing effort to a few kilos, strong balancing springs are pivoted between said rear wall and the rear end of the levers. This conventional mechanism disclosed in, for example, GB-1 121 585 , though effective, has various drawbacks both in manufacturing and use.
In the first place the lateral levers with the relevant balancing springs are bulky, they make the external cleaning operations difficult and may pose a risk during the hood moving phases.
Secondly, the balancing springs must be very strong and therefore heavy and expensive, since the lever arm of the hood is many times greater than the reaction lever arm of the springs with respect to the fulcrum of rotation of the lateral levers. For example, considering a hood that weighs 30 kg with a lever arm variable between 360 and 340 mm (depending on the closed or open position of the hood), two springs pivoted on the lateral levers with a lever arm variable between 40 and 60 mm must exert a force variable between 270 and 170 kg. This gives rise to high stress of the involved mechanical parts, in addition to difficulties in mounting and maintenance.
Therefore the object of the present invention is to provide a hood-type industrial dishwasher which overcomes the above-mentioned drawbacks. This object is achieved by means of a hood-type industrial dishwasher provided with a hood moving mechanism including vertical rear telescopic guides driven by cables on which the balancing springs act through mobile pulleys mounted on rotatable plates. Other advantageous features of the present industrial dishwasher are specified in the dependent claims.
The main advantage of the dishwasher according to the present invention is that of dispensing with the bulky and potentially dangerous lateral levers and springs by achieving the hood moving through a mechanism fully arranged on the back of the machine. This results in a smaller width of the dishwasher, an increased safety and a great easiness of the external cleaning operations.
A further advantage of this dishwasher is the significant reduction in the maximum load of the springs, thanks to the use of the pulley and to the advantageous reaction lever arm. As a consequence, it is possible to use less strong, lighter and cheaper springs and therefore achieve less difficulties in mounting/maintenance and lower mechanical stress, thus increasing reliability.
Still another advantage of the above-mentioned dishwasher, in a preferred embodiment thereof, is that of being able to automatically open and close the hood through the addition of a single-piston device of limited length and force and therefore inexpensive. In this way, the machine can open the hood exactly at the end of the wash cycle, making even more evident to the operator that the dishwasher has finished its work and therefore facilitating the loading/unloading operations.
Furthermore, it should be noted that the manual moving of the hood both in opening and closing can be retained possible even in the presence of the automatic moving piston, by providing a second pair of rotatable plates located between the piston and the pulley-carrying plates.
These and other advantages and characteristics of the industrial dishwasher according to the present invention will be clear to those skilled in the art from the following detailed description of two embodiments thereof, with reference to the annexed drawings wherein:

Fig.1 is a diagrammatic side view showing a hood-type dishwasher according to the invention in a closed position for the washing of the dishes;
Fig.2 is a diagrammatic side view showing said dishwasher in an open position for the loading/unloading of the dishes;
Fig.3 is a diagrammatic rear view of the dishwasher showing the moving mechanism in a first embodiment with manual drive;
Fig.4 shows the operation of the mechanism of Fig.3 by means of two partial diagrammatic rear views respectively corresponding to the closed and open position of the dishwasher;
Fig.5 is a diagrammatic rear view of the dishwasher showing the moving mechanism in a second embodiment with automatic drive and possible manual drive;
Fig.6 is a partial diagrammatic rear view of the dishwasher of Fig.5 showing the mechanism in the closed hood position;
Fig.7 is a partial diagrammatic rear view of the dishwasher of Fig.5 showing the mechanism in the open hood position, said position having been reached through manual drive;
Fig.8 is a partial diagrammatic rear view of the dishwasher of Fig.5 showing the mechanism in the initial phase of the automatic drive; and
Fig.9 is a partial diagrammatic rear view of the dishwasher of Fig.5 showing the mechanism in the open hood position, said position having been reached through automatic drive.

Referring to Figs. 1-3, there is seen that a hood-type industrial dishwasher according to the present invention conventionally includes a hood 1 mounted on vertical guides arranged along the rear wall of the stationary lower part of the dishwasher. Hood 1 slides vertically along said guides with a run Y sufficient to allow a smooth loading/unloading of the dishes.
The novel aspect of the industrial dishwasher according to the present invention is the use of telescopic guides 3 including a sliding part 2 to which hood 1 is secured. Said telescopic guides 3 are obviously sized to support the weight of hood 1 when the sliding parts 2 project at the top for a length Y equal to the opening run of hood 1.
The movement of hood 1 is driven through a mechanism fully arranged on the back of the dishwasher, in order to achieve the above-mentioned object of dispensing with the lateral levers and balancing springs. Since, as shown in Fig.3, said moving mechanism includes two identical devices preferably arranged mirror-like with respect to the vertical midplane of the dishwasher, the following description refers to one of the devices only.
An inextensible cable 4 is secured between a bottom attachment 4', arranged at the bottom end of the sliding part 2 of the telescopic guide 3, and a top attachment 4" fixed on the dishwasher structure. In its path between the two attachments 4', 4" the cable first passes over an idler wheel 5 fixed on the dishwasher structure, then under a pulley 6 arranged on a plate 7 that is in turn mounted in a rotatable way on the dishwasher structure (at a position lower than wheel 5) through a fulcrum A.
Furthermore, a balancing spring 8 is pivoted between a bottom attachment 8', fixed on the dishwasher structure close to the bottom, and a top attachment 8" fixed on plate 7 at a position intermediate between fulcrum A and the rotation pin C of pulley 6. The position of the top attachment 8" is designed so as to obtain an extension and an angle of spring 8 suitable to balance the weight of hood 1 with respect to fulcrum A depending on the angular position of pulley 6, i.e. of plate 7.
Like in conventional dishwashers with lateral levers, but in this case even more precisely and in a simpler way, the positions of the attachments and the spring loads are calculated to obtain:

in the closed position, a reaction of springs 8 insufficient to balance the weight of hood 1 in order to prevent its rise during the wash cycle, whereby the operator must exert a raising effort on the handle between 2 and 4 kg to raise hood 1;
during the rise, for a length of run between about 150 and 250 mm, a reaction of springs 8 greater than the weight of hood 1 that therefore tends to rise by itself;
beyond an opening height of 300 mm, a reaction of springs 8 substantially equal to the weight of hood 1 that therefore remains open (due to the frictions) until the operator has completed the loading/unloading operations.

It should be noted that the above-illustrated arrangement of the elements is given only by way of example since several other arrangements, even non-symmetrical, are possible. For example, the sequence from the side towards the center of elements 2, 5, 6, 4", 8" and A is a consequence of the arrangement of guides 3 close to the dishwasher sides, but if guides 3 were arranged at a more central position the relevant moving devices could be arranged more outwardly and the above sequence of elements would be reversed.
Similarly, the whole opening mechanism could be located higher or mirrored in the vertical direction (by adding a further idler wheel) simply changing the fixing points of elements 4, 5, 7 and 8 on the dishwasher structure. Moreover, the bottom attachment 4' of cable 4 may also be arranged higher than the bottom end of the sliding part 2, as long as it remains at a distance from the idler wheel 5 greater than run Y.
The simple and effective operation of the hood moving mechanism of the dishwasher according to the present invention will be readily understood from the description given above.
As shown in Fig.4, when hood 1 is closed (in a static condition and therefore without frictions) the force Cc exerted on pulley 6 is equal to the weight of hood 1 since, notoriously: Cc = Pg * 2 = Pc
where: Pc= weight of hood 1
Pg = Pc/2 = pull exerted on cable 4 by the sliding part 2
In this condition, the force Cc generates a moment with respect to fulcrum A which is equal to Bcc * Pc, not completely balanced by the moment generated by spring 8 which is equal to Fmc * Bmc
where: Bcc = arm of force Cc with hood closed
Fmc = force exerted by spring 8 with hood closed
Bmc = arm of force Fmc with hood closed
During the opening of hood 1 it is obvious that, while Pc remains constant, both the force arms and the force exerted by spring 8 change continuously and have been calculated to obtain the above-described type of movement.
At the end of the opening of hood 1, the sliding part 2 will have moved upwards through a distance equal to run Y whereas pulley 6, due to the rotation of plate 7, will have moved downwards through a distance equal to Y/2.
In this condition, the force Cc generates a moment with respect to fulcrum A which is equal to Bca * Pc, completely balanced by the moment generated by spring 8 which is equal to Fma * Bma
where: Bca = arm of force Cc with hood open
Fma = force exerted by spring 8 with hood open
Bma = arm of force Fma with hood open
As clearly illustrated in Fig.4, in this novel moving mechanism for hood 1 the arms of the forces exerted by the balancing springs 8 are not many times smaller than the arms of the weight of hood 1 as in conventional dishwashers, since Bcc is just about twice Bmc while Bca is less than 50% greater than Bma. As a consequence, in order to move a hood of the same weight it is possible to use less strong and therefore cheaper and more reliable springs.
Referring now to Figs.5-9, there is illustrated a second embodiment of the mechanism which provides the automatic drive of hood I by means of a second rotatable plate 9, pivoted on the same fulcrum A of the first plate 7, driven by a piston 10 whose stem is connected thereto through a rod 11 pivoted between the stem of piston 10 and a pin B located at the bottom end of the second plate 9. It should be noted that, in the preferred embodiment with symmetrical structure of the mechanism, a single vertical piston 10 arranged at a central position is sufficient to drive both moving devices that make up the mechanism.
As previously mentioned, this second embodiment is preferably made so as to allow the manual drive of hood I even in the presence of piston 10 for the automatic drive. To this purpose, the connection between the first plate 7 and the second plate 9 is achieved through a pin P fixed on plate 7 which slidably engages a slot S formed in plate 9. More specifically, slot S is shaped like an arc of circle centered on fulcrum A and pin P is located on plate 7 so as to abut on the internal end of slot S when hood 1 is closed (Fig.6).
In this way, if the operator decides to open the hood manually the mechanism makes the normal movement described above with reference to Fig.4, this being made possible by the fact that pin P slides along slot S allowing the rotation of plate 7 through the whole foreseen run Y without any interference by plate 9 (Fig.7). Obviously, in case of manual opening of hood 1 also the subsequent closing must be performed manually by the operator since piston 10 has not extended its stem.
Otherwise, if the operator decides for the automatic opening of the hood, at the end of the wash cycle piston 10 extends its stem pushing into rotation plate 9 around fulcrum A through rod 11 and pin B. As a consequence, plate 9 rotates plate 7 through the internal end of slot S that pushes on pin P, as shown in Fig.8 where Bp1 is the arm of the push exerted by rod 11 and Bp2 is the arm of the push exerted by slot S.
At the end of the opening run Y, as shown in Fig.9, plate 7 has reached its usual position already illustrated in Figs.4 and 7 but in this case the stem of piston 10 is extended and plate 9 is rotated whereby pin P is still abutting on the internal end of slot S. As a consequence, also in the case of automatic opening the subsequent closing must be performed manually by the operator, since when piston 10 rotates plate 9 in the opposite direction, slot S slides with respect to pin P without causing the rotation of plate 7.
To obtain also the automatic closing of the hood it is necessary to have plates 7 and 9 connected through a bidirectional restraint rather than the simple abutment of slot S on pin P; suitable means may be provided to this purpose to give the operator the choice of the type of hood drive. However, in case of automatic closing the second plate 9 could be completely dispensed with, i.e. it would be possible to combine the two plates into a single plate 7 shaped to have an extension 9 to which rod 11 is pivoted. Moreover, in order to prevent damages to people or things during the automatic closing of the hood, there is provided a control system that stops the drive of piston 10 in case the hood finds an obstacle during its descent.
It should be noted that in Figs.5-9 plate 9 is illustrated arranged between plate 7 and the dishwasher back in order to facilitate the mounting of spring 8 on the outside of plate 7, but it would also be possible to change the relative positions of these three elements as long as their rotation is unhampered.
It is clear that the above-described and illustrated embodiments of the dishwasher according to the invention are just examples susceptible of various modifications. In particular, in addition to the possible modifications mentioned above, the exact number, shape and arrangement of the elements could be changed according to specific manufacturing needs, e.g. by changing the path of cable 4 with further idler wheels, as long as the passage over pulley 6 carried by rotatable plate 7 is retained. Furthermore, the mechanism could include more than two moving devices if hood 1 is mounted on a corresponding number of telescopic guides 3.
Similarly, piston 10 could be of any type (electric, hydraulic, pneumatic) as well as springs 8, and these elements could be replaced by other technically equivalent elements such as other types of actuators or other types of resilient members.
Finally, it should be noted that there are preferably provided, though not illustrated in the drawings, means for adjusting the length of cables 4, springs 8 and rods 11 (e.g. at one or more of the attachments 4', 4", 8', 8" and/or at pins B and C) in order to achieve a perfect alignment of the two devices making up the moving mechanism.

Claims

Hood-type industrial dishwasher including a hood (1) mounted on at least two vertical guides arranged on the rear wall of the stationary lower part of said dishwasher, said hood (1) sliding vertically along said guides with the help of balancing springs (8) suitable to limit the hood (1) opening/closing effort, characterized in that the at least two guides are telescopic guides (3) including sliding parts (2) on which the hood (1) is secured, the movement of said sliding parts (2) being driven by cables (4) on which said balancing springs (8) act through mobile pulleys (6) arranged on plates (7) that are mounted in a rotatable way on the dishwasher structure, said elements (2, 3, 4, 6, 7) making part of the hood (1) moving mechanism being arranged on the back of the dishwasher.
Hood-type industrial dishwasher according to claim 1, characterized in that to each telescopic guide (3) there is associated a moving device comprising a cable (4), secured between a first attachment (4') arranged on the sliding part (2) of said telescopic guide (3) and a second attachment (4") fixed on the dishwasher structure, at least an idler wheel (5) fixed on the dishwasher structure, a pulley (6) arranged on a plate (7) that is mounted in a rotatable way on the dishwasher structure through a fulcrum (A), and a balancing spring (8) pivoted between a first attachment (8') fixed on the dishwasher structure and a second attachment (8") fixed on said plate (7) at a position intermediate between said fulcrum (A) and the rotation pin (C) of said pulley (6).
Hood-type industrial dishwasher according to claim 1 or 2, characterized in that the hood (1) moving mechanism includes two identical moving devices arranged mirror-like with respect to the vertical midplane of the dishwasher.
Hood-type industrial dishwasher according to any of the preceding claims, characterized in that it includes at least one actuator suitable to drive the rotation of the rotatable plates (7).
Hood-type industrial dishwasher according to claims 3 and 4, characterized in that the actuator is located at a central position so as to be able to drive both moving devices.
Hood-type industrial dishwasher according to claim 4 or 5, characterized in that the actuator is a piston (10) whose stem is connected to the moving device through a rod (11) pivoted between said stem and a pin (B) located at the end of the moving device.
Hood-type industrial dishwasher according to any of claims 4 to 6, characterized in that each moving device further includes a second rotatable plate (9) pivoted on the same fulcrum (A) of the first rotatable plate (7), the connection between said plates (7, 9) being achieved through a pin (P) fixed on the first plate (7) which slidably engages a slot (S) formed in the second plate (9), said slot (S) being shaped like an arc of circle centered on the fulcrum (A) and said pin (P) being located on the first plate (7) so as to abut on the internal end of the slot (S) when the hood (1) is closed.
Hood-type industrial dishwasher according to the preceding claim, characterized in that it further includes means for achieving a bidirectional restraint between the two plates (7, 9).
Hood-type industrial dishwasher according to any of claims 4 to 8, characterized in that it further includes a control system suitable to stop the drive of the actuator in case the hood (1) finds an obstacle during its descent.
Hood-type industrial dishwasher according to any of the preceding claims, characterized in that it further includes means for adjusting the length of the cables (4) and/or of the springs (8) and/or of the rods (11) suitable to achieve an alignment of the devices making up the moving mechanism.