EP2011941A1

EP2011941A1 - Hinge for household appliance door

Info

Publication number: EP2011941A1
Application number: EP07425408A
Authority: EP
Inventors: Andrea Ambrosi
Original assignee: Bonferraro SpA
Current assignee: Bonferraro SpA
Priority date: 2007-07-05
Filing date: 2007-07-05
Publication date: 2009-01-07

Abstract

A hinge for household appliance door includes a rotating plate (3) secured to the appliance structure through a rotation fulcrum (4), a door mounting bracket (5) connected to the plate (3) through an articulated lever system, and a spring (1) connected to the plate (3) so as to apply thereto a door closing torque, the connection between the spring (1) and the plate (3) being achieved through a connecting plate (16) provided with a first shaped slot (17) suitable to slidably receive a rear hooking pin (18) integral with the rotating plate (3), as well as a second shaped slot (19) suitable to slidably receive a forward hooking pin (2) integral with the rotating plate (3) at a position more to the front with respect to said rear hooking pin (18), the shape, size and position of said slots (17, 19) being such that in the initial door opening phase the rear hooking pin (18) abuts against the bottom of the first slot (17) and acts as connecting pin to transmit the force of the spring (1) to the plate (3) with a reduced arm (L'), and then the function of transmitting the force of the spring (1) is transferred from the rear hooking pin (18) to the forward hooking pin (2) that abuts against the bottom of the second slot (19) and acts with a much longer arm (L). In this way, the hinge is able to provide the required hold to the door at any opening angle without the need for a high strength spring (1), whereby the reliability of the hinge is increased and also the spring (1) mounting step is easier.

Description

The present invention relates to hinges used for household appliance doors, and in particular to a "variable arm" hinge for a door rotating around a horizontal axis. Specific reference will be made in the following to a dishwasher door, while it is clear that what is being said is also applicable to other types of household appliances such as ovens, washing machines, etc.
It is known that a dishwasher door is usually hinged to the machine frame along its bottom side through fixed fulcrum hinges, constructionally simple and particularly reliable, that often also have the function of "balancing" the door by means of slide pads used as brakes, or through the adjustment of the spring pull and therefore of the exerted closing torque.
In other words, the hinge is able to hold the door at any intermediate position between the closed position and the open position thanks to the friction exerted by said pads against suitable guides or by changing the force exerted by the spring. The adjustment of the hinge torque may be required to adapt it to the weight of the door, which may be provided with a decorative panel.
In some cases in order to hold a heavy door at its opening angle from 20-30 degrees to the 90 degrees of maximum opening it is necessary to provide a high torque, that can be obtained by adjusting the spring at a very high strength or by increasing the arm of application of the spring force with respect to the rotation fulcrum.
However this latter arrangement, more advantageous from the reliability point of view since the spring is less stressed, prevents the door balancing in the first 20-30 degrees of opening in that even if at that position the spring is almost unloaded the arm is so long that it generates a closing torque which exceeds the balancing need. As a consequence, in order to achieve the balancing also in the first 20-30 degrees and to prevent the door from banging at the end of the closing movement, the general tendency is that of using a strong spring with a short arm.
Therefore the object of the present invention is to provide a hinge which overcomes said drawbacks. This object is achieved by means of a variable arm hinge having the characteristics disclosed in claim 1. Other advantageous features of the present hinge are disclosed in the dependent claims.
The main advantage of the hinge according to the present invention stems from the fact that it can provide the required hold to the door at any opening angle without the need for a high strength spring. As a consequence, the reliability of the hinge is increased and also the spring mounting step is easier.
A second significant advantage of said hinge is its structural simplicity, since with respect to a conventional hinge it only requires the addition of a pin and a connecting plate with two shaped slots.
These and other advantages and characteristics of the hinge according to the present invention will be clear to those skilled in the art from the following detailed description of an embodiment thereof, with reference to the annexed drawings wherein:

Fig.1 is a diagrammatic side view of a conventional hinge applied to a dishwasher, in the position corresponding to the almost closed door;
Fig.2 is a partially see-through view similar to the preceding one of a hinge according to the present invention;
Fig.3 is a perspective partially exploded view of the above-mentioned hinge;
Fig.4 is a perspective view of the hinge in the completely closed position;
Figs.5 and 6 are perspective views of the hinge at two intermediate opening positions; and
Fig.7 is a perspective view of the hinge in the completely open position.

With reference to figure 1, there is seen that a conventional hinge includes a spring 1 that is hooked through a connecting pin 2 to a rotating plate 3 secured to the dishwasher structure through a rotation fulcrum 4. The arm for the application of the force of spring 1 corresponds to the distance L between pin 2 and fulcrum 4, and said arm remains substantially constant at any position of the door.
The connection with the bracket 5 for mounting the door (not illustrated) is achieved through an articulated lever system comprising elements pivoted between bracket 5 and plate 3. More specifically, an upper arm 6 is pivoted between bracket 5 and plate 3 through a first and a second upper pivot 7 and 8, respectively, while a lower arm 9 is secured to the dishwasher structure through a rotation fulcrum 10 and pivoted between bracket 5, through a first lower pivot 11, and an auxiliary arm 12, through a second lower pivot 13, said auxiliary arm 12 being in turn pivoted to plate 3 through a third lower pivot 14.
The novel aspect of the present hinge resides in the presence of a connecting plate arranged between spring 1 and the rotating plate 3, which is provided with a second pin to alternately engage said connecting plate at a forward or rear position according to the position of the door.
As shown in figures 2-4, the bottom end of spring 1 rather than being hooked to pin 2 is hooked to a connecting pin 15 located at the top of a connecting plate 16, which is joined to the rotating plate 3 through a first shaped slot 17 that slidably receives a rear hooking pin 18 integral with plate 3. Said hooking pin 18 is located at a position more to the rear and preferably lower than pin 2, which in this case acts as forward hooking pin and is slidably received in a corresponding second shaped slot 19.
More specifically, both slots 17, 19 preferably have a widened top portion that allows the introduction of pins 18 and 2, respectively, and extend downward with an arcuate profile and a reduced width that assures the engagement of the pin heads, that are substantially "mushroom-shaped". The first slot 17 that receives the rear pin 18 is preferably shorter than the second slot 19, and in the initial door opening phase illustrated in figures 2-4 the rear pin 18 abuts against the bottom of slot 17 and acts as connecting pin to transmit the force of spring 1 to plate 3.
Thanks to the rear position of said pin 18, it is clear that the hinge according to the present invention achieves the advantage of having arm L' of the force exerted by spring 1 which is much shorter than arm L corresponding to the forward position of pin 2, that on the contrary is not abutting against the bottom of slot 19 and therefore does not transmit any force. This reduced arm L' thus allows to achieve the object of balancing the door in the first 20-30 degrees of opening yet with a spring which is not very strong and therefore more reliable.
In the light of the description above, the simple and reliable operation of the hinge according to the present invention is readily understood.
Starting from the closed position of figure 4, during the opening of the door plate 3 rotates around fulcrum 4, counter-clockwise in the illustrated example, with the rear pin 18 engaged at the bottom of slot 17 that provides the force for balancing the door in the first 20-30 degrees. When the position illustrated in figure 5 is reached, the rotation of plate 3 has brought the forward pin 2 to the bottom of the corresponding slot 19, whereby the function of transmitting the force of spring 1 is transferred from pin 18 to pin 2 that acts with a much longer arm.
In the successive phases of the rotation of plate 3 up to the complete opening of the door (figs.6-7) the rear pin 18 slides upwards along the corresponding slot 17, whereas the forward pin 2 remains engaged at the bottom of slot 19 to transmit the force needed to balance the door. Obviously, a reverse movement with respect to the one illustrated above takes place in the door closing phase.
It is clear that the above-described and illustrated embodiment of the hinge according to the invention is just an example susceptible of various modifications. In particular, the exact shape, size and position of slots 17, 19, and consequently of pins 2 and 18, may change depending on the opening angle at which one desires to achieve the passage from the shorter arm L' to the longer arm L.
Similarly, the exact structure of the articulated lever system connecting the door bracket 5 to the rotating plate 3 may be changed according to specific needs, and the bottom end of spring 1 or the top of plate 16 may be changed to obtain a direct hooking into a hole of plate 16 thus dispensing with pin 15.

Claims

Hinge for household appliance door, including a rotating plate (3) secured to the appliance structure through a rotation fulcrum (4), a door mounting bracket (5) connected to said rotating plate (3) through an articulated lever system, and a spring (1) connected to the rotating plate (3) so as to apply thereto a door closing torque, characterized in that the connection between said spring (1) and the rotating plate (3) is achieved through a connecting plate (16) provided with a first shaped slot (17) suitable to slidably receive a rear hooking pin (18) integral with the rotating plate (3), as well as a second shaped slot (19) suitable to slidably receive a forward hooking pin (2) integral with the rotating plate (3) at a position more to the front with respect to said rear hooking pin (18), the shape, size and position of said slots (17, 19) being such that in the initial door opening phase the rear hooking pin (18) abuts against the bottom of the first slot (17) and acts as connecting pin to transmit the force of the spring (1) to the rotating plate (3), and then the function of transmitting the force of the spring (1) is transferred from the rear hooking pin (18) to the forward hooking pin (2) that abuts against the bottom of the second slot (19).
Hinge according to claim 1, characterized in that the initial door opening phase ends at an opening angle between 20 and 30 degrees.
Hinge according to claim 1 or 2, characterized in that the spring (1) is hooked to the connecting plate (16) through a connecting pin (15) located at the top of the latter.
Hinge according to one of the preceding claims, characterized in that the slots (17, 19) have a widened top portion that allows the introduction of the pins (18, 2) and extend downward with an arcuate profile and a reduced width that assures the engagement of the heads of the pins (18, 2) that are substantially "mushroom-shaped" .
Hinge according to one of the preceding claims, characterized in that the rear hooking pin (18) is located on the rotating plate (3) at a position which is lower than the forward hooking pin (2).
Hinge according to one of the preceding claims, characterized in that the first slot (17) is shorter than the second slot (19).
Hinge according to one of the preceding claims, characterized in that the articulated lever system connecting the bracket (5) to the rotating plate (3) includes an upper arm (6) pivoted between the bracket (5) and the rotating plate (3) through a first and a second upper pivot (7, 8), a lower arm (9) secured to the appliance structure through a rotation fulcrum (10) and pivoted to the bracket (5) through a first lower pivot (11), and an auxiliary arm (12) pivoted between said lower arm (9) and the plate (3) through a second and third lower pivot (13, 14).