This application is a United States Non-Provisional Utility Patent
Application claiming the benefit of Italian Patent Application Number TO2012A000307 filed on 6 Apr. 2012, which is incorporated herein in its entirety.
The present invention relates to an annular sealing device adapted to be interposed between two relatively rotating mechanical elements; in particular, the sealing device of the invention is conceived to be used on an electric household appliance, and is specifically adapted to be inserted on the actuating shaft of the drum of a washing machine for implementing a seal between two relatively rotating members consisting of the shaft itself and the washing tank in which in use the drum rotate, in order to retain, on the one hand, a washing fluid in the tank, so as to prevent leaks, and on the other hand, protect a bearing supporting the drum driving shaft from water infiltrations, all ensuring an excellent seal with minimal frictions and noise.
EP 1514966A1 describes several arrangements of sealing assemblies adapted to prevent water leaks from the tank at the passage seat for the drum driving shaft and likewise to protect the support bearings of such drum shaft; in all these arrangements, the sealing assemblies used, having one or more sealing lips, only implement a radial seal, directly on the drum driving shaft. In some embodiments, one of the sealing lips is charged by a toroidal spring, which has the purpose of increasing the radial pressure exerted by the lip; in all cases, the sealing assembly must then be at least partly protected from the contact with the washing fluid, on the side facing the tank, by means of a rigid plastic shield, which shield, however, does not cooperate with any of the sealing lips.
However, the sealing assemblies shown in EP 1514966A1, briefly described above, have several drawbacks, especially in the arrangements disclosed. Firstly, they have high friction, connected with the relatively high contact pressures exerted by the sealing lips, especially if they are charged by springs. This leads to high energy consumptions of the electric household appliance and above all to premature wearing of the sealing lips. Secondly, during the insertion of the drum driving shaft into the passage defined by the annular sealing lips, a part of the lubrication grease arranged close to the water sealing lip, which in use faces the sealing seat, may be removed. This further decreases useful life of the sealing lips and increases the frictions. Finally, the overall dimensions of the sealing assembly and of the related protective shield are relatively high.
The object of the present invention is to provide an annular sealing device specifically designed to be used on electric household appliances, and thus characterized by cost-effective construction solutions, which is free from the above-described drawbacks and especially capable of ensuring an excellent seal towards the washing fluid present in the tank of a washing machine, accompanied by reduced frictions and thus, by a low energy consumption, low or absent noise, small overall dimensions and which ensures an optimal lubrication of the sealing lip arranged in use towards the washing fluid.
A sealing device is thus provided according to the invention, in particular insertable between two members in relative rotation between which a washing fluid is present, as defined in claim 1.
Features and advantages of the present invention will appear clearly from the following description of a non-limiting embodiment thereof, made with reference to the figures in the accompanying drawings, in which:
With reference to
The sealing device 1 comprises a rigid annular shield 5 adapted to be integrally restrained, in use, to the mechanical element 2, which is stationary in use, and an annular sealing element 6 made of elastomeric material and integrally carried by shield 5.
The sealing element 6 comprises a first elastically deformable annular lip 7 which, in radial section, obliquely extends so as to protrude from shield 5, radially towards the inside of shield 5 and axially from the side of a first face 8 of shield 5. The sealing element 6 further comprises a second elastically deformable annular lip 9 which, in radial section, obliquely extends so as to protrude from shield 5, radially towards the inside of shield 5 and axially from the side of a second face 10 of the shield, opposite to the first face 8.
According to an aspect of the invention, the sealing element 6 also comprises a third elastically deformable annular lip 11 which, in radial section, obliquely extends so as to protrude from shield 5 and radially towards the inside of shield 5 and which is arranged, according to an axial direction, i.e. according to a direction parallel to a symmetry axis A of the annular shield 5, between the first lip 7 and the second lip 9.
Lip 11 axially extends from the same side as the first lip 7 (i.e. from the side of face 8) and is oriented and sized so as to remain always axially spaced apart from lip 7, both in underformed conditions (
Moreover, lip 11 integrally forms a V-shaped rocker-arm structure in radial section with lip 9: in fact, lips 9 and 11 obliquely extend so as to protrude in opposite directions from a common annular root portion 14 of the elastomeric annular element 6, thus forming a V in radial section therebetween, having its vertex arranged at the root portion 14 and radially facing outwards.
In particular, the annular root portion 14 radially extends so as to protrude from a radially inner edge 15 of shield 5, radially towards the inside of shield 5 and, in use, towards the mechanical element 3, and it has a narrow portion 16 arranged substantially on the middle line measured in an axial direction, so as to define a common elastic hinge C for the second lip 9 and the third lip 11, which elastic hinge C radially connects lips 9 and 11, in a rocker-arm pivoting manner, with edge 15.
According to the invention, in combination with the above-described structural features, lips 7, 9 and 11 are radially delimited towards the interior by respective edges, respectively indicated with reference numerals 17, 18 and 19 which, with lips 7, 9, 11 in underformed conditions, have a substantially circular shape and which have diameters D chosen so that edges 17 and 18 have respective diameters D3 and D2 smaller than diameter D1 of edge 19 of the third lip 11.
In particular, diameter D1 is chosen so as to be larger than the diameter of the mechanical element (rotating shaft) 3, while diameters D3 and D2 are chosen so that lips 7 and 9 interfere in use, either directly or indirectly, with shaft 3. More specifically, lips 7, 9 and 11 are adapted in use (
Lip 7 is the main sealing lip and axially extends, in use, in a direction opposite to an insertion direction V (
The diameter of edges 18 and 19 of lips 9 and 11 and the length of axial extension of lips 9 and 11 are chosen in combination with each other so that, in use, the second lip 9 always interferes, either directly or indirectly (“indirectly” according to the above-mentioned meaning with regard to the above-mentioned possible variant not shown), with the second mechanical element 3 to produce a rocker-arm rotation of the V structure defined by lips 9 and 11 obtained integrally with and protruding from the root portion 14, about the common elastic hinge C, according to the arrows shown in
In particular, a rocker-arm rotation of the second and third lips 9 and 11 about the common elastic hinge C defined by the narrow portion 16 of the common root portion 14, is carried out, due to the above-described difference between diameters D2 and D1, in such a direction as to move edge 19 of the third lip 11 away from lip 7, as shown by the left curved arrow in
Such rotation makes, in use, edge 19 of lip 11 interfere, either directly or indirectly (by “indirectly” meaning what specified above with reference to the above-mentioned possible variant not shown), with the second mechanical element 3.
Moreover, lip 19 is oriented so as to axially project into the annular chamber 12 defined between it and lip 7, so as to be adapted to retain in use the lubricating grease 13 in a radial direction therein, which grease therefore cannot “drop” out of chamber 12.
The annular shield 5 comprises a flange portion 22 defining the first and second faces 8 and 10 of shield 5 with its own respective opposite axial surfaces; shield 5 further comprises a first radially inner sleeve portion 23, which defines the radially inner edge 15 and which axially extends so as to protrude from the flange portion 22, over a predetermined axial length, from the side opposite to the first face 8 and to the axial extension direction of the first lip 7.
The annular root portion 14 of the second and third lips 9 and 11 radially extends so as to protrude from a first end 24 of the sleeve portion 23, opposite to the flange portion 22 and defining the free end of the sleeve portion 23; vice versa, the first lip 7 radially extends so as to protrude from a second end 25 of the sleeve portion 23; end 25 is opposite to end 24 and is immediately adjacent to the flange portion 22.
The annular shield 5 further comprises a second radially external sleeve portion 26, which axially extends so as to protrude from the flange portion 22, from the side opposite to face 8 and to the axial extension direction of lip 7 and adapted, in use, to couple with the first mechanical element 2 in an angularly integral and substantially known manner.
In particular, the sleeve portion 26 is at least partially embedded in the annular sealing element 6, which extends over the first face 8 starting from a root portion 27 of lip 7 and, again starting from the root portion 7, over the sleeve portion 23, radially on the inside and up to the common root portion 14 of lips 9 and 11.
In order to control the axial overall dimensions, the flange portion 22 of the annular shield 5 is provided in the radial section and radially inwards, with an axial fold 28 directed from the side opposite to the axial extension direction of lip 25 so as to define an annular shallow recess 29 in which lip 7 projects from the side of face 8.
In this way, while the axial overall dimensions of the sealing device 1 are controlled, a sliding seal is obtained in use on shaft 3 implemented by all the three lips 7, 9 and 11 on a stretch of axial length almost equal to the axial overall dimensions of device 1. Grease 13 is easily retained in chamber 12 but, above all, it cannot be pushed away, wholly or partly, as it happens instead in known sealing assemblies, when the shaft or element 3 is inserted into the through passage 21, due to the fact that lips 7 and 11 axially extend from the same side and are actually substantially or almost parallel.
Such a retaining action of grease 13 is made even more effective by the fact that lip 11 forms a single V-shaped, rocker-arm operating element, with lip 9, which rotates about hinge C, and by the relative dimensions of lips 9 and 11. In fact, the interference between lip 9 and element 3 causes, in the assembly step 1, the rotation in opposite directions of lip 9, which moves away from axis A, and of lip 11, which on the other hand approaches axis A, thereby interfering with element 3 while, in the first assembly step, when lip 9 has not “touched” element 3 yet, a predetermined radial clearance exists between lip 11 and element 3.
On the one hand, this “rotation” allows the removal of grease 13 to be prevented more effectively and above all, it allows lip 11 to be made fluid-tightly operating towards the washing fluid 4, due to the fact that lips 7 and 11 are oriented towards the same side. The dynamic sealing action towards fluid 4 is thus doubled and a correct lubrication of edge 17 of lip 7 is ensured at the same time, which extends the operating life thereof. Moreover, the interference of lip 9 is reduced, thereby reducing frictions.
Number | Date | Country | Kind |
---|---|---|---|
TO2012A000307 | Apr 2012 | IT | national |