Piston for use in friction damper for washing machine and corresponding friction damper

Abstract

Disclosed is a piston (11) for use in a friction damper for a washing machine, comprising a hollow shaft (111) and a ring (112) for fastening the piston (11) to a washing machine frame or drum, the ring comprising a portion introduced inside the shaft (111) and a portion protruding therefrom, the protruding portion of the ring (112) comprising a fastening portion (1121) for fastening the piston (11) to the washing machine frame or drum, the portion introduced inside the shaft (111) comprises: a shaped portion (1122) for fastening the ring (112) to the shaft (111); a first thickened portion (1124) having a circular cross-section and dimensions such that it can be introduced into the shaft (111), the first thickened portion being arranged at an opposite portion of the fastening portion (1121) with respect to the shaped portion (1122), the shaped portion (1122) having a non-circular cross-sectional shape, inscribed within the shape of the thickened portion (1124) and provided with at least one plane of symmetry, the first thickened portion (1124) having a circular cross-section and dimensions such that it can be introduced into the shaft (111), the first thickened portion (1124) being arranged at an opposite portion of the fastening portion (1121) with respect to the shaped portion (1122). The fastening of the shaft (111) to the ring (112) is obtained by plastic deformation of the shaft at the shaped portion. The utility model further discloses a corresponding friction damper.

Description

Technical Field

[0001] The purpose of this invention is to provide a piston for a friction damper in a washing machine, the piston having an optimized connection.

[0002] Specifically, the purpose of this invention is to provide a piston for a friction damper in a washing machine that is more reliable in resisting fatigue stress compared to pistons known in the prior art, can be made with less material, and can be produced in faster working cycles, thus optimizing performance and reducing costs compared to pistons known in the prior art. Background Technology

[0003] The use of friction dampers in washing machines is known. They are devices fastened to the washing machine drum and frame to reduce noise and vibration caused by the centrifugal force of an electric washing machine.

[0004] Generally, known embodiments in the prior art include: a housing (or outer tube) having a generally tubular shape and opening to one end; and a piston that slides inside the housing, the housing and piston being fastened to a frame and the washing machine drum, respectively. The piston is achieved by means of a cylindrical tube made of metal foil of suitable thickness. To allow for the fastening of the shock absorber, both the piston and the housing include a shell with a circular seat. This shell is typically obtained as a single piece, while the piston is achieved by connecting elements of plastic material (typically polypropylene) to the metal tube.

[0005] Furthermore, the shock absorber includes one or more friction rings positioned between the sliding piston and the housing, configured to dampen alternating oscillations of the piston caused by the rotation of the washing machine drum relative to the frame. According to some embodiments, these friction rings may be positioned within a cage that slides relative to both the piston and the housing, mounted inside the housing but outside the piston, or they may be of a fixed type, introduced into a suitable shell obtained within the inner wall of the housing. The shock absorber also includes a cap disposed within an open end of the housing, into which the piston is introduced.

[0006] Existing technical references

[0007] In the prior art, various embodiments of friction dampers for washing machines are known, and they basically work according to the content just explained.

[0008] Document EP1584730 (one of its views in this application) Figure 12 The image shows a friction damper for a washing machine, which is provided with a closed cap with an elastic tongue. A variation is described in document EP1637640 (one view of which is shown in...). Figure 13(as shown in the figure), which describes a shock absorber in which the cap includes internal teeth that act as a stop for the cage, and a friction ring is disposed inside the cage.

[0009] In document EP3809010 (one of its views is in) Figure 14 As shown in [reference needed], a shock absorber for a washing machine is described, wherein the cap and housing are assembled by means of axial movement when positioned in precise relative positions to each other. A similar embodiment is described in document DE202016102547 (part of which is shown in [reference needed]). Figure 15 (as shown in the image).

[0010] Slightly different embodiments from the ones just cited are described in documents EP1754908 and EP2406519. Utility Model Content

[0011] Technical issues

[0012] The known embodiments in the prior art have limitations, particularly in terms of implementation cost and piston mechanical performance.

[0013] In fact, it has been observed that the need for rolling to achieve the fastening between the tube and the connecting component results in a localized reduction in the thickness of the metal foil forming the piston tube, requiring the use of a tube with an undeformed thickness (typically about 1 mm) greater than the undeformed thickness required to resist the loads of the project. This is the first known disadvantage of pistons in the prior art.

[0014] Furthermore, while the tensile strength of the fastening between the connector and the tube is obtained through the shape, the torsional strength is obtained through the friction generated between the tube and the connector. However, this does not allow for reliable knowledge of the connection performance, which depends on the maximum frictional intensity that can be applied between the tube and the connector, and therefore implies the need to increase the size of the contact surface and the fastening torque during rolling. This is the second drawback of the embodiments known in the prior art.

[0015] Furthermore, the need for friction alone determines another source of uncertainty in piston performance during operation.

[0016] In fact, it is known that friction generated on the piston by frictional elements inside the housing dissipates kinetic energy as heat. This heat raises the piston's temperature, and since the piston is metallic and a good conductor, this temperature increase further heats the connecting elements, thus raising their temperature as well. Therefore, it is clear that the component's performance—regarding tensile strength—depends not only on the maximum friction that can be developed (which remains an uncertain parameter) but also on its variation with temperature (which is even more uncertain).

[0017] The technical objective of this utility model

[0018] Therefore, the purpose of this invention is to provide a shock absorber for a washing machine that overcomes the limitations of known embodiments in the prior art, and in particular, the piston provided by this shock absorber can be implemented in a more economical and faster manner compared with that provided by shock absorbers known in the prior art, and this piston also allows for better mechanical performance, especially with regard to torsional strength.

[0019] According to another purpose, the present invention provides a piston for a friction damper that achieves all the objectives just described, and can be used with known dampers without requiring modifications to the housing, cap and other components of the damper or washing machine.

[0020] Brief Description of the Technical Solution of This Utility Model

[0021] In a first aspect, the present invention achieves the above-mentioned objective because it is a piston used in a friction damper for a washing machine, comprising:

[0022] - A shaft having a hollow circular cross-section, and

[0023] A ring, used to secure the piston to the frame or drum of a washing machine, the ring comprising a portion introduced into the interior of the shaft and a portion projecting out therefrom.

[0024] The protruding portion of the ring includes a fastening portion for securing the piston to the frame or drum of the washing machine.

[0025] The portion introduced into the shaft includes:

[0026] - A forming portion, which is used to fasten the ring to the shaft;

[0027] - A first thickened portion having a circular cross-section and dimensions such that it can be introduced into the shaft. The first thickened portion is arranged about the opposite portion of the fastening portion with respect to the forming portion. The forming portion includes a plurality of faces angled to each other in a cross-section orthogonal to the axis of the shaft. The forming portion is inscribed in the shape of the first thickened portion and is provided with at least one plane of symmetry passing through the axis of the shaft. The fastening of the shaft to the ring is achieved by plastic deformation of the shaft relative to its undeformed circular shape at the forming portion, which is achieved by means of the movement of a pair of dies at the forming portion.

[0028] In some embodiments, each of the surfaces is recessed.

[0029] In some embodiments, the shaped portion has six sides.

[0030] In some embodiments, the size of the axial development portion (L) of the formed portion is between 30% and 50% of the inner diameter of the shaft.

[0031] In some embodiments, the ring further includes an abutting portion located between the fastening portion and the forming portion, the abutting portion having a diameter equal to the outer diameter of the shaft and having a flat abutting surface.

[0032] In some embodiments, the ring further includes a second thickened portion between the abutting portion and the forming portion, the outer diameter of the second thickened portion being equal to the outer diameter of the first thickened portion.

[0033] In some embodiments, the shaft is made of a metal tube and the ring is made of a plastic material.

[0034] In a second aspect, the present invention provides a friction damper for a washing machine, comprising a housing having a ring for fastening to the frame or drum of the washing machine and being open at one end, and a piston according to the first aspect being slidably connected to the housing. Attached Figure Description

[0035] Please refer to the appendix Figures 1 to 11 A detailed description of some preferred embodiments of the present invention is provided.

[0036] Figures 1 to 5 and Figures 12 to 15 A view of an embodiment known in the prior art is shown.

[0037] Figure 6 An assembled view of the piston according to the present invention is shown, with details of the piston in... Figure 7 As shown in the image.

[0038] Figure 8 , Figure 9 and Figure 10 Three views of the fastening element according to the present invention without a metal tube are shown.

[0039] Figure 11 A partial cross-sectional view of the piston according to the present invention is shown, wherein only the cross-sectional view is shown.

[0040] Figure 16 and Figure 17 Two cross-sectional views of a known embodiment in the prior art and a piston according to the present invention are shown respectively.

[0041] Figure 18 A cross-sectional view of the housing is shown, in which the piston according to the present invention is introduced. Detailed Implementation

[0042] like Figure 1 As shown, a friction damper for a washing machine 1 includes a housing 20, which is open at one end, through which a piston 10 slides, the piston 10 protruding from the open end of the housing. A friction element (not shown) is disposed inside the housing 20, and the housing 20 is provided with a ring 21 for fastening to the frame or drum of the washing machine. It should be understood that all the elements just described are known in the prior art, and any variations thereof known in the prior art can be used in conjunction with the piston of this invention without departing from the purpose of this invention.

[0043] Based on what is known in the prior art and Figure 2 The piston 10 shown includes a shaft 101 and a ring 102 for securing the piston 10 to the frame or drum of a washing machine. The shaft 101 is made of a metal tube, while the ring 102 is made of a plastic material. The fastening between the ring 102 and the shaft 101 is achieved by rolling.

[0044] For this purpose, the ring 102 includes a circular recess 1021, around which the shaft 101 is introduced, and then the shaft 101 is deformed by the rotation of the two rollers.

[0045] On the contrary, such as Figure 6 As shown, the piston 11 according to the present invention includes a shaft 111 having a hollow circular cross-section and a ring 112 for fastening the piston 11 to a frame or drum of a washing machine. The shaft 111 is made of a metal tube, the ring 112 is made of a plastic material, and the fastening of the ring 112 to the shaft 111 is achieved by a press 113, i.e., by means of the plastic deformation of the material of the shaft 111, which is achieved by means of the movement of a pair of dies at a portion of the ring 112 having a non-circular cross-section.

[0046] In fact, the piston is characterized in that the ring 112 includes a fastening portion 1121 for fastening to a frame or roller, a forming portion 1122 for fastening to a shaft 111, and a thickening portion 1124, the thickening portion 1124 having a circular cross-section and dimensions such that it can be introduced into the shaft 111, the thickening portion 1124 being arranged about the opposite portion of the ring 112 with respect to the forming portion 1122. Therefore, the axially extended portion L of the forming portion 1122 defines a deformation area of ​​the shaft 111 during the assembly process. Not to limit the scope of the invention, the axially extended portion L has a dimension between 30% and 50% of the inner diameter of the shaft 111.

[0047] When viewed in cross-section, the formed portion 1122 has a non-circular shape incorporating the shape of the thickened portion 1124, such that when the shaft 111 deforms to attach to the surface 1123, as Figure 11As shown, the thickened portion 1124 prevents the shaft 111 from sliding axially relative to the ring 112.

[0048] The fact that the formed part has a non-circular shape in the cross section prevents the ring 112 from rotating relative to the shaft 111.

[0049] Furthermore, preferably, the ring 112 includes an abutment portion 1126 located between the fastening portion 1121 and the forming portion 1122, the abutment portion 1126 having a diameter equal to the outer diameter of the shaft 111 and having a flat abutment surface 1261, such that when the ring 112 is introduced into the shaft 111, the relative axial position of the two components is determined.

[0050] Furthermore, preferably, the ring 112 also includes a second thickened portion 1125 located between the abutting portion 1126 and the forming portion 1122, the outer diameter of the second thickened portion 1125 being equal to that of the first thickened portion 1124.

[0051] According to one embodiment, the non-circular shape includes a plurality of faces 1123, which are angled relative to each other and each face is provided with a notch, such as... Figure 17 The cross-sectional view is shown in the figure. An embodiment with six faces is shown in the figure, but different numbers of faces can be used without departing from the purpose of this invention.

[0052] Preferably, the non-circular shape is provided with at least one plane of symmetry passing through the axis of the shaft 111, such that deformation of the shaft 111 around the forming portion can occur by means of two dies having the same geometry approaching each other in a direction perpendicular to the plane of symmetry.

[0053] Therefore, the assembly of the ring 112 and the shaft 111 is achieved by introducing the circular thickened portion 1124 and the shaped portion 1122 into the shaft 111, which is in its undeformed structure.

[0054] Next, the shaft is deformed to attach to the shaped portion, thus presenting Figure 6 and Figure 11 The construction shown.

[0055] Depending on the shape of the component, both axial fastening and relative rotation are locked, and friction is not required—unlike in embodiments known in the prior art.

[0056] Furthermore, even though the fastening conditions obtained are more reliable than those known in the prior art, the material of shaft 111 requires less deformation, and this allows for the use of shafts made of sheets with a lower thickness (also 0.4-0.5 mm) compared to the thickness (1 mm) commonly used.

[0057] Another advantage is that the fastening time required by crimping is less than that required by rolling, which has a significant positive impact on the total working time of the workpiece.

[0058] It can be observed that none of the examples of the prior art shown achieve the results just listed: even though many embodiments of friction dampers for washing machines are known and have been designed by many companies to date, employing a technique of connecting the shaft and ring by rolling, this has all the disadvantages just described.

Claims

1. A piston (11) used in a friction damper for a washing machine, comprising: - Shaft (111), the shaft having a hollow circular cross section, and - Ring (112), the ring being used to secure the piston (11) to the frame or drum of the washing machine, the ring comprising a portion introduced into the interior of the shaft (111) and a portion projecting therefrom, The protruding portion of the ring (112) includes a fastening portion (1121) for securing the piston (11) to the frame or drum of the washing machine. It is characterized in that The portion introduced into the interior of the shaft (111) includes: - A shaped portion (1122) for fastening the ring (112) to the shaft (111); - A first thickened portion (1124), having a circular cross-section and dimensions such that it can be introduced into the shaft (111), the first thickened portion being arranged relative to the forming portion (1122) at the opposite portion of the fastening portion (1121). and The formed portion (1122) includes a plurality of surfaces (1123) at angles to each other in a cross section orthogonal to the axis of the shaft (111). The formed portion is inscribed within the shape of the first thickened portion (1124) and has at least one plane of symmetry passing through the axis of the shaft (111). and The fastening of the shaft (111) to the ring (112) is achieved by the plastic deformation of the shaft (111) at the forming portion relative to its undeformed circular shape, which is achieved by means of the movement of a pair of dies at the forming portion.

2. The piston (11) used in a friction damper for a washing machine according to claim 1, characterized in that, Each of the faces (1123) is concave.

3. The piston (11) used in a friction damper for a washing machine according to claim 1, characterized in that, The forming part has six sides.

4. The piston (11) used in a friction damper for a washing machine according to claim 1, characterized in that, The axial development portion (L) of the formed portion (1122) is between 30% and 50% of the inner diameter of the shaft (111).

5. The piston (11) used in a friction damper for a washing machine according to claim 1, characterized in that, The ring (112) further includes an abutting portion (1126) which is located between the fastening portion (1121) and the forming portion (1122). The abutting portion (1126) has a diameter equal to the outer diameter of the shaft (111) and is provided with a flat abutting surface (1261).

6. The piston (11) used in a friction damper for a washing machine according to claim 5, characterized in that, The ring (112) further includes a second thickened portion (1125) between the abutting portion (1126) and the forming portion (1122), the outer diameter of the second thickened portion being equal to the outer diameter of the first thickened portion (1124).

7. The piston (11) used in a friction damper for a washing machine according to any one of claims 1 to 6, characterized in that, The shaft (111) is made of a metal tube, and the ring (112) is made of plastic material.

8. A friction damper for a washing machine (1), comprising a housing (20) having a ring (21) for fastening to a frame or drum of the washing machine and open at one end, characterized in that, The piston (11) according to any one of claims 1 to 7 is slidably connected to the housing.

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